TY - JOUR A1 - Dornelas, Maria A1 - Antão, Laura H. A1 - Moyes, Faye A1 - Bates, Amanda E. A1 - Magurran, Anne E. A1 - Adam, Dušan A1 - Akhmetzhanova, Asem A. A1 - Appeltans, Ward A1 - Arcos, José Manuel A1 - Arnold, Haley A1 - Ayyappan, Narayanan A1 - Badihi, Gal A1 - Baird, Andrew H. A1 - Barbosa, Miguel A1 - Barreto, Tiago Egydio A1 - Bässler, Claus A1 - Bellgrove, Alecia A1 - Belmaker, Jonathan A1 - Benedetti-Cecchi, Lisandro A1 - Bett, Brian J. A1 - Bjorkman, Anne D. A1 - Błażewicz, Magdalena A1 - Blowes, Shane A. A1 - Bloch, Christopher P. Bloch A1 - Bonebrake, Timothy C. A1 - Boyd, Susan A1 - Bradford, Matt A1 - Brooks, Andrew J. A1 - Brown, James H. A1 - Bruelheide, Helge A1 - Budy, Phaedra A1 - Carvalho, Fernando A1 - Castañeda-Moya, Edward A1 - Chen, Chaolun Allen A1 - Chamblee, John F. A1 - Chase, Tory J. A1 - Siegwart Collier, Laura A1 - Collinge, Sharon K. A1 - Condit, Richard A1 - Cooper, Elisabeth J. A1 - Cornelissen, J. Hans C. A1 - Cotano, Unai A1 - Crow, Shannan Kyle A1 - Damasceno, Gabriella A1 - Davies, Claire H. A1 - Davis, Robert A. A1 - Day, Frank P. A1 - Degraer, Steven A1 - Doherty, Tim S. A1 - Dunn, Timothy E. A1 - Durigan, Giselda A1 - Duffy, J. Emmett A1 - Edelist, Dor A1 - Edgar, Graham J. A1 - Elahi, Robin A1 - Elmendorf, Sarah C. A1 - Enemar, Anders A1 - Ernest, S. K. Morgan A1 - Escribano, Rubén A1 - Estiarte, Marc A1 - Evans, Brian S. A1 - Fan, Tung-Yung A1 - Turini Farah, Fabiano A1 - Loureiro Fernandes, Luiz A1 - Farneda, Fábio Z. A1 - Fidelis, Alessandra A1 - Fitt, Robert A1 - Fosaa, Anna Maria A1 - Franco, Geraldo Antonio Daher Correa A1 - Frank, Grace E. A1 - Fraser, William R. A1 - García, Hernando A1 - Cazzolla Gatti, Roberto A1 - Givan, Or A1 - Gorgone-Barbosa, Elizabeth A1 - Gould, William A. A1 - Gries, Corinna A1 - Grossman, Gary D. A1 - Gutierréz, Julio R. A1 - Hale, Stephen A1 - Harmon, Mark E. A1 - Harte, John A1 - Haskins, Gary A1 - Henshaw, Donald L. A1 - Hermanutz, Luise A1 - Hidalgo, Pamela A1 - Higuchi, Pedro A1 - Hoey, Andrew A1 - Van Hoey, Gert A1 - Hofgaard, Annika A1 - Holeck, Kristen A1 - Hollister, Robert D. A1 - Holmes, Richard A1 - Hoogenboom, Mia A1 - Hsieh, Chih-hao A1 - Hubbell, Stephen P. A1 - Huettmann, Falk A1 - Huffard, Christine L. A1 - Hurlbert, Allen H. A1 - Ivanauskas, Natália Macedo A1 - Janík, David A1 - Jandt, Ute A1 - Jażdżewska, Anna A1 - Johannessen, Tore A1 - Johnstone, Jill A1 - Jones, Julia A1 - Jones, Faith A. M. A1 - Kang, Jungwon A1 - Kartawijaya, Tasrif A1 - Keeley, Erin C. A1 - Kelt, Douglas A. A1 - Kinnear, Rebecca A1 - Klanderud, Kari A1 - Knutsen, Halvor A1 - Koenig, Christopher C. A1 - Kortz, Alessandra R. A1 - Král, Kamil A1 - Kuhnz, Linda A. A1 - Kuo, Chao-Yang A1 - Kushner, David J. A1 - Laguionie-Marchais, Claire A1 - Lancaster, Lesley T. A1 - Lee, Cheol Min A1 - Lefcheck, Jonathan S. A1 - Lévesque, Esther A1 - Lightfoot, David A1 - Lloret, Francisco A1 - Lloyd, John D. A1 - López-Baucells, Adrià A1 - Louzao, Maite A1 - Madin, Joshua S. A1 - Magnússon, Borgþór A1 - Malamud, Shahar A1 - Matthews, Iain A1 - McFarland, Kent P. A1 - McGill, Brian A1 - McKnight, Diane A1 - McLarney, William O. A1 - Meador, Jason A1 - Meserve, Peter L. A1 - Metcalfe, Daniel J. A1 - Meyer, Christoph F. J. A1 - Michelsen, Anders A1 - Milchakova, Nataliya A1 - Moens, Tom A1 - Moland, Even A1 - Moore, Jon A1 - Moreira, Carolina Mathias A1 - Müller, Jörg A1 - Murphy, Grace A1 - Myers-Smith, Isla H. A1 - Myster, Randall W. A1 - Naumov, Andrew A1 - Neat, Francis A1 - Nelson, James A. A1 - Nelson, Michael Paul A1 - Newton, Stephen F. A1 - Norden, Natalia A1 - Oliver, Jeffrey C. A1 - Olsen, Esben M. A1 - Onipchenko, Vladimir G. A1 - Pabis, Krzysztof A1 - Pabst, Robert J. A1 - Paquette, Alain A1 - Pardede, Sinta A1 - Paterson, David M. A1 - Pélissier, Raphaël A1 - Peñuelas, Josep A1 - Pérez-Matus, Alejandro A1 - Pizarro, Oscar A1 - Pomati, Francesco A1 - Post, Eric A1 - Prins, Herbert H. T. A1 - Priscu, John C. A1 - Provoost, Pieter A1 - Prudic, Kathleen L. A1 - Pulliainen, Erkki A1 - Ramesh, B. R. A1 - Ramos, Olivia Mendivil A1 - Rassweiler, Andrew A1 - Rebelo, Jose Eduardo A1 - Reed, Daniel C. A1 - Reich, Peter B. A1 - Remillard, Suzanne M. A1 - Richardson, Anthony J. A1 - Richardson, J. Paul A1 - van Rijn, Itai A1 - Rocha, Ricardo A1 - Rivera-Monroy, Victor H. A1 - Rixen, Christian A1 - Robinson, Kevin P. A1 - Rodrigues, Ricardo Ribeiro A1 - de Cerqueira Rossa-Feres, Denise A1 - Rudstam, Lars A1 - Ruhl, Henry A1 - Ruz, Catalina S. A1 - Sampaio, Erica M. A1 - Rybicki, Nancy A1 - Rypel, Andrew A1 - Sal, Sofia A1 - Salgado, Beatriz A1 - Santos, Flavio A. M. A1 - Savassi-Coutinho, Ana Paula A1 - Scanga, Sara A1 - Schmidt, Jochen A1 - Schooley, Robert A1 - Setiawan, Fakhrizal A1 - Shao, Kwang-Tsao A1 - Shaver, Gaius R. A1 - Sherman, Sally A1 - Sherry, Thomas W. A1 - Siciński, Jacek A1 - Sievers, Caya A1 - da Silva, Ana Carolina A1 - da Silva, Fernando Rodrigues A1 - Silveira, Fabio L. A1 - Slingsby, Jasper A1 - Smart, Tracey A1 - Snell, Sara J. A1 - Soudzilovskaia, Nadejda A. A1 - Souza, Gabriel B. G. A1 - Souza, Flaviana Maluf A1 - Souza, Vinícius Castro A1 - Stallings, Christopher D. A1 - Stanforth, Rowan A1 - Stanley, Emily H. A1 - Sterza, José Mauro A1 - Stevens, Maarten A1 - Stuart-Smith, Rick A1 - Suarez, Yzel Rondon A1 - Supp, Sarah A1 - Tamashiro, Jorge Yoshio A1 - Tarigan, Sukmaraharja A1 - Thiede, Gary P. A1 - Thorn, Simon A1 - Tolvanen, Anne A1 - Toniato, Maria Teresa Zugliani A1 - Totland, Ørjan A1 - Twilley, Robert R. A1 - Vaitkus, Gediminas A1 - Valdivia, Nelson A1 - Vallejo, Martha Isabel A1 - Valone, Thomas J. A1 - Van Colen, Carl A1 - Vanaverbeke, Jan A1 - Venturoli, Fabio A1 - Verheye, Hans M. A1 - Vianna, Marcelo A1 - Vieira, Rui P. A1 - Vrška, Tomáš A1 - Vu, Con Quang A1 - Vu, Lien Van A1 - Waide, Robert B. A1 - Waldock, Conor A1 - Watts, Dave A1 - Webb, Sara A1 - Wesołowski, Tomasz A1 - White, Ethan P. A1 - Widdicombe, Claire E. A1 - Wilgers, Dustin A1 - Williams, Richard A1 - Williams, Stefan B. A1 - Williamson, Mark A1 - Willig, Michael R. A1 - Willis, Trevor J. A1 - Wipf, Sonja A1 - Woods, Kerry D. A1 - Woehler, Eric J. A1 - Zawada, Kyle A1 - Zettler, Michael L. T1 - BioTIME: A database of biodiversity time series for the Anthropocene JF - Global Ecology and Biogeography N2 - Motivation The BioTIME database contains raw data on species identities and abundances in ecological assemblages through time. These data enable users to calculate temporal trends in biodiversity within and amongst assemblages using a broad range of metrics. BioTIME is being developed as a community-led open-source database of biodiversity time series. Our goal is to accelerate and facilitate quantitative analysis of temporal patterns of biodiversity in the Anthropocene. Main types of variables included The database contains 8,777,413 species abundance records, from assemblages consistently sampled for a minimum of 2 years, which need not necessarily be consecutive. In addition, the database contains metadata relating to sampling methodology and contextual information about each record. Spatial location and grain BioTIME is a global database of 547,161 unique sampling locations spanning the marine, freshwater and terrestrial realms. Grain size varies across datasets from 0.0000000158 km2 (158 cm2) to 100 km2 (1,000,000,000,000 cm2). Time period and grain BioTIME records span from 1874 to 2016. The minimal temporal grain across all datasets in BioTIME is a year. Major taxa and level of measurement BioTIME includes data from 44,440 species across the plant and animal kingdoms, ranging from plants, plankton and terrestrial invertebrates to small and large vertebrates. Software format .csv and .SQL. KW - biodiversity KW - global KW - spatial KW - species richness KW - temporal KW - turnover Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-222846 VL - 27 ER - TY - JOUR A1 - Moll, Julia A1 - Kellner, Harald A1 - Leonhardt, Sabrina A1 - Stengel, Elisa A1 - Dahl, Andreas A1 - Bässler, Claus A1 - Buscot, François A1 - Hofrichter, Martin A1 - Hoppe, Björn T1 - Bacteria inhabiting deadwood of 13 tree species are heterogeneously distributed between sapwood and heartwood JF - Environmental Microbiology N2 - Deadwood represents an important structural component of forest ecosystems, where it provides diverse niches for saproxylic biota. Although wood-inhabiting prokaryotes are involved in its degradation, knowledge about their diversity and the drivers of community structure is scarce. To explore the effect of deadwood substrate on microbial distribution, the present study focuses on the microbial communities of deadwood logs from 13 different tree species investigated using an amplicon based deep-sequencing analysis. Sapwood and heartwood communities were analysed separately and linked to various relevant wood physico-chemical parameters. Overall, Proteobacteria, Acidobacteria and Actinobacteria represented the most dominant phyla. Microbial OTU richness and community structure differed significantly between tree species and between sapwood and heartwood. These differences were more pronounced for heartwood than for sapwood. The pH value and water content were the most important drivers in both wood compartments. Overall, investigating numerous tree species and two compartments provided a remarkably comprehensive view of microbial diversity in deadwood. Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224168 VL - 20 ER - TY - JOUR A1 - Hilmers, Torben A1 - Friess, Nicolas A1 - Bässler, Claus A1 - Heurich, Marco A1 - Brandl, Roland A1 - Pretzsch, Hans A1 - Seidl, Rupert A1 - Müller, Jörg T1 - Biodiversity along temperate forest succession JF - Journal of Applied Ecology N2 - 1. The successional dynamics of forests—from canopy openings to regeneration, maturation, and decay—influence the amount and heterogeneity of resources available for forest-dwelling organisms. Conservation has largely focused only on selected stages of forest succession (e.g., late-seral stages). However, to develop comprehensive conservation strategies and to understand the impact of forest management on biodiversity, a quantitative understanding of how different trophic groups vary over the course of succession is needed. 2. We classified mixed mountain forests in Central Europe into nine successional stages using airborne LiDAR. We analysed α- and β-diversity of six trophic groups encompassing approximately 3,000 species from three kingdoms. We quantified the effect of successional stage on the number of species with and without controlling for species abundances and tested whether the data fit the more-individuals hypothesis or the habitat heterogeneity hypothesis. Furthermore, we analysed the similarity of assemblages along successional development. 3. The abundance of producers, first-order consumers, and saprotrophic species showed a U-shaped response to forest succession. The number of species of producer and consumer groups generally followed this U-shaped pattern. In contrast to our expectation, the number of saprotrophic species did not change along succession. When we controlled for the effect of abundance, the number of producer and saproxylic beetle species increased linearly with forest succession, whereas the U-shaped response of the number of consumer species persisted. The analysis of assemblages indicated a large contribution of succession-mediated β-diversity to regional γ-diversity. 4. Synthesis and applications. Depending on the species group, our data supported both the more-individuals hypothesis and the habitat heterogeneity hypothesis. Our results highlight the strong influence of forest succession on biodiversity and underline the importance of controlling for successional dynamics when assessing biodiversity change in response to external drivers such as climate change. The successional stages with highest diversity (early and late successional stages) are currently strongly underrepresented in the forests of Central Europe. We thus recommend that conservation strategies aim at a more balanced representation of all successional stages. KW - biodiversity KW - forest dynamics KW - forest succession KW - habitat heterogeneity KW - LiDAR KW - species density KW - temperate forests KW - β-diversity Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-320632 VL - 55 ER - TY - JOUR A1 - Hillaert, Jasmijn A1 - Hovestadt, Thomas A1 - Vandegehuchte, Martijn L. A1 - Bonte, Dries T1 - Size-dependent movement explains why bigger is better in fragmented landscapes JF - Ecology and Evolution N2 - Body size is a fundamental trait known to allometrically scale with metabolic rate and therefore a key determinant of individual development, life history, and consequently fitness. In spatially structured environments, movement is an equally important driver of fitness. Because movement is tightly coupled with body size, we expect habitat fragmentation to induce a strong selection pressure on size variation across and within species. Changes in body size distributions are then, in turn, expected to alter food web dynamics. However, no consensus has been reached on how spatial isolation and resource growth affect consumer body size distributions. Our aim was to investigate how these two factors shape the body size distribution of consumers under scenarios of size-dependent and size-independent consumer movement by applying a mechanistic, individual-based resource–consumer model. We also assessed the consequences of altered body size distributions for important ecosystem traits such as resource abundance and consumer stability. Finally, we determined those factors that explain most variation in size distributions. We demonstrate that decreasing connectivity and resource growth select for communities (or populations) consisting of larger species (or individuals) due to strong selection for the ability to move over longer distances if the movement is size-dependent. When including size-dependent movement, intermediate levels of connectivity result in increases in local size diversity. Due to this elevated functional diversity, resource uptake is maximized at the metapopulation or metacommunity level. At these intermediate levels of connectivity, size-dependent movement explains most of the observed variation in size distributions. Interestingly, local and spatial stability of consumer biomass is lowest when isolation and resource growth are high. Finally, we highlight that size-dependent movement is of vital importance for the survival of populations or communities within highly fragmented landscapes. Our results demonstrate that considering size-dependent movement is essential to understand how habitat fragmentation and resource growth shape body size distributions—and the resulting metapopulation or metacommunity dynamics—of consumers. KW - allometric scaling KW - body size distributions; KW - eco-evolutionary dynamics KW - habitat fragmentation KW - isolation KW - metabolic theory KW - optimal size KW - size-dependent movement Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-320322 VL - 8 ER - TY - JOUR A1 - Stein, Katharina A1 - Stenchly, Kathrin A1 - Coulibaly, Drissa A1 - Pauly, Alain A1 - Dimobe, Kangbeni A1 - Steffan-Dewenter, Ingolf A1 - Konaté, Souleymane A1 - Goetze, Dethardt A1 - Porembski, Stefan A1 - Linsenmair, K. Eduard T1 - Impact of human disturbance on bee pollinator communities in savanna and agricultural sites in Burkina Faso, West Africa JF - Ecology and Evolution N2 - All over the world, pollinators are threatened by land-use change involving degradation of seminatural habitats or conversion into agricultural land. Such disturbance often leads to lowered pollinator abundance and/or diversity, which might reduce crop yield in adjacent agricultural areas. For West Africa, changes in bee communities across disturbance gradients from savanna to agricultural land are mainly unknown. In this study, we monitored for the impact of human disturbance on bee communities in savanna and crop fields. We chose three savanna areas of varying disturbance intensity (low, medium, and high) in the South Sudanian zone of Burkina Faso, based on land-use/land cover data via Landsat images, and selected nearby cotton and sesame fields. During 21 months covering two rainy and two dry seasons in 2014 and 2015, we captured bees using pan traps. Spatial and temporal patterns of bee species abundance, richness, evenness and community structure were assessed. In total, 35,469 bee specimens were caught on 12 savanna sites and 22 fields, comprising 97 species of 32 genera. Bee abundance was highest at intermediate disturbance in the rainy season. Species richness and evenness did not differ significantly. Bee communities at medium and highly disturbed savanna sites comprised only subsets of those at low disturbed sites. An across-habitat spillover of bees (mostly abundant social bee species) from savanna into crop fields was observed during the rainy season when crops are mass-flowering, whereas most savanna plants are not in bloom. Despite disturbance intensification, our findings suggest that wild bee communities can persist in anthropogenic landscapes and that some species even benefitted disproportionally. West African areas of crop production such as for cotton and sesame may serve as important food resources for bee species in times when resources in the savanna are scarce and receive at the same time considerable pollination service. KW - bee communities KW - cotton KW - sesame KW - species spillover KW - sub-Saharan Africa Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-239999 VL - 8 ER - TY - JOUR A1 - Minden, Vanessa A1 - Schnetger, Bernhard A1 - Pufal, Gesine A1 - Leonhardt, Sara D. T1 - Antibiotic-induced effects on scaling relationships and on plant element contents in herbs and grasses JF - Ecology and Evolution N2 - Plant performance is correlated with element concentrations in plant tissue, which may be impacted by adverse chemical soil conditions. Antibiotics of veterinary origin can adversely affect plant performance. They are released to agricultural fields via grazing animals or manure, taken up by plants and may be stored, transformed or sequestered by plant metabolic processes. We studied the potential effects of three antibiotics (penicillin, sulfadiazine, and tetracycline) on plant element contents (macro- and microelements). Plant species included two herb species (Brassica napus and Capsella bursa-pastoris) and two grass species (Triticum aestivum and Apera spica-venti), representing two crop species and two noncrop species commonly found in field margins, respectively. Antibiotic concentrations were chosen as to reflect in vivo situations, that is, relatively low concentrations similar to those detected in soils. In a greenhouse experiment, plants were raised in soil spiked with antibiotics. After harvest, macro- and microelements in plant leaves, stems, and roots were determined (mg/g). Results indicate that antibiotics can affect element contents in plants. Penicillin exerted the greatest effect both on element contents and on scaling relationships of elements between plant organs. Roots responded strongest to antibiotics compared to stems and leaves. We conclude that antibiotics in the soil, even in low concentrations, lead to low-element homeostasis, altering the scaling relationships between roots and other plant organs, which may affect metabolic processes and ultimately the performance of a plant. KW - antibiotics KW - homeostasis KW - scaling relationships KW - standardized major axis regression KW - tissue nutrient contents Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224094 VL - 8 ER - TY - JOUR A1 - Schubert, Frank K. A1 - Hagedorn, Nicolas A1 - Yoshii, Taishi A1 - Helfrich-Förster, Charlotte A1 - Rieger, Dirk T1 - Neuroanatomical details of the lateral neurons of Drosophila melanogaster support their functional role in the circadian system JF - Journal of Comparative Neurology N2 - Drosophila melanogaster is a long-standing model organism in the circadian clock research. A major advantage is the relative small number of about 150 neurons, which built the circadian clock in Drosophila. In our recent work, we focused on the neuroanatomical properties of the lateral neurons of the clock network. By applying the multicolor-labeling technique Flybow we were able to identify the anatomical similarity of the previously described E2 subunit of the evening oscillator of the clock, which is built by the 5th small ventrolateral neuron (5th s-LNv) and one ITP positive dorsolateral neuron (LNd). These two clock neurons share the same spatial and functional properties. We found both neurons innervating the same brain areas with similar pre- and postsynaptic sites in the brain. Here the anatomical findings support their shared function as a main evening oscillator in the clock network like also found in previous studies. A second quite surprising finding addresses the large lateral ventral PDF-neurons (l-LNvs). We could show that the four hardly distinguishable l-LNvs consist of two subgroups with different innervation patterns. While three of the neurons reflect the well-known branching pattern reproduced by PDF immunohistochemistry, one neuron per brain hemisphere has a distinguished innervation profile and is restricted only to the proximal part of the medulla-surface. We named this neuron “extra” l-LNv (l-LNvx). We suggest the anatomical findings reflect different functional properties of the two l-LNv subgroups. KW - circadian clock neurons KW - Drosophila melanogaster KW - flybow KW - morphology KW - RRID: AB_760350 KW - RRID: AB_2315460 KW - RRID: AB_2314242 KW - RRID: AB_2315311 KW - RRID: AB_2314041 KW - RRID: AB_300798 Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-234477 VL - 526 ER - TY - JOUR A1 - Flunkert, Julia A1 - Maierhofer, Anna A1 - Dittrich, Marcus A1 - Müller, Tobias A1 - Horvath, Steve A1 - Nanda, Indrajit A1 - Haaf, Thomas T1 - Genetic and epigenetic changes in clonal descendants of irradiated human fibroblasts JF - Experimental Cell Research N2 - To study delayed genetic and epigenetic radiation effects, which may trigger radiation-induced carcinogenesis, we have established single-cell clones from irradiated and non-irradiated primary human fibroblasts. Stable clones were endowed with the same karyotype in all analyzed metaphases after 20 population doublings (PDs), whereas unstable clones displayed mosaics of normal and abnormal karyotypes. To account for variation in radiation sensitivity, all experiments were performed with two different fibroblast strains. After a single X-ray dose of 2 Gy more than half of the irradiated clones exhibited radiation-induced genome instability (RIGI). Irradiated clones displayed an increased rate of loss of chromosome Y (LOY) and copy number variations (CNVs), compared to controls. CNV breakpoints clustered in specific chromosome regions, in particular 3p14.2 and 7q11.21, coinciding with common fragile sites. CNVs affecting the FHIT gene in FRA3B were observed in independent unstable clones and may drive RIGI. Bisulfite pyrosequencing of control clones and the respective primary culture revealed global hypomethylation of ALU, LINE-1, and alpha-satellite repeats as well as rDNA hypermethylation during in vitro ageing. Irradiated clones showed further reduced ALU and alpha-satellite methylation and increased rDNA methylation, compared to controls. Methylation arrays identified several hundred differentially methylated genes and several enriched pathways associated with in vitro ageing. Methylation changes in 259 genes and the MAP kinase signaling pathway were associated with delayed radiation effects (after 20 PDs). Collectively, our results suggest that both genetic (LOY and CNVs) and epigenetic changes occur in the progeny of exposed cells that were not damaged directly by irradiation, likely contributing to radiation-induced carcinogenesis. We did not observe epigenetic differences between stable and unstable irradiated clones. The fact that the DNA methylation (DNAm) age of clones derived from the same primary culture varied greatly suggests that DNAm age of a single cell (represented by a clone) can be quite different from the DNAm age of a tissue. We propose that DNAm age reflects the emergent property of a large number of individual cells whose respective DNAm ages can be highly variable. KW - copy number variation (CNV) KW - delayed radiation effects KW - DNA methylation (DNAm) age KW - global DNA methylation KW - loss of chromosome Y (LOY); KW - methylation array analysis KW - radiation-induced genome instability (RIGI) Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228177 VL - 370 ER - TY - JOUR A1 - Göttlich, Claudia A1 - Kunz, Meik A1 - Zapp, Cornelia A1 - Nietzer, Sarah L. A1 - Walles, Heike A1 - Dandekar, Thomas A1 - Dandekar, Gudrun T1 - A combined tissue-engineered/in silico signature tool patient stratification in lung cancer JF - Molecular Oncology N2 - Patient-tailored therapy based on tumor drivers is promising for lung cancer treatment. For this, we combined in vitro tissue models with in silico analyses. Using individual cell lines with specific mutations, we demonstrate a generic and rapid stratification pipeline for targeted tumor therapy. We improve in vitro models of tissue conditions by a biological matrix-based three-dimensional (3D) tissue culture that allows in vitro drug testing: It correctly shows a strong drug response upon gefitinib (Gef) treatment in a cell line harboring an EGFR-activating mutation (HCC827), but no clear drug response upon treatment with the HSP90 inhibitor 17AAG in two cell lines with KRAS mutations (H441, A549). In contrast, 2D testing implies wrongly KRAS as a biomarker for HSP90 inhibitor treatment, although this fails in clinical studies. Signaling analysis by phospho-arrays showed similar effects of EGFR inhibition by Gef in HCC827 cells, under both 2D and 3D conditions. Western blot analysis confirmed that for 3D conditions, HSP90 inhibitor treatment implies different p53 regulation and decreased MET inhibition in HCC827 and H441 cells. Using in vitro data (western, phospho-kinase array, proliferation, and apoptosis), we generated cell line-specific in silico topologies and condition-specific (2D, 3D) simulations of signaling correctly mirroring in vitro treatment responses. Networks predict drug targets considering key interactions and individual cell line mutations using the Human Protein Reference Database and the COSMIC database. A signature of potential biomarkers and matching drugs improve stratification and treatment in KRAS-mutated tumors. In silico screening and dynamic simulation of drug actions resulted in individual therapeutic suggestions, that is, targeting HIF1A in H441 and LKB1 in A549 cells. In conclusion, our in vitro tumor tissue model combined with an in silico tool improves drug effect prediction and patient stratification. Our tool is used in our comprehensive cancer center and is made now publicly available for targeted therapy decisions. KW - 3D lung tumor model KW - Boolean signaling network KW - chemoresistance KW - HSP90 inhibitor KW - insilico drug screening too KW - KRAS mutation signature Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-233137 VL - 12 ER - TY - JOUR A1 - van de Peppel, L. J. J. A1 - Aanen, D. K. A1 - Biedermann, P. H. W. T1 - Low intraspecific genetic diversity indicates asexuality and vertical transmission in the fungal cultivars of ambrosia beetles JF - Fungal Ecology N2 - Ambrosia beetles farm ascomycetous fungi in tunnels within wood. These ambrosia fungi are regarded asexual, although population genetic proof is missing. Here we explored the intraspecific genetic diversity of Ambrosiella grosmanniae and Ambrosiella hartigii (Ascomycota: Microascales), the mutualists of the beetles Xylosandrus germanus and Anisandrus dispar. By sequencing five markers (ITS, LSU, TEF1α, RPB2, β-tubulin) from several fungal strains, we show that X. germanus cultivates the same two clones of A. grosmanniae in the USA and in Europe, whereas A. dispar is associated with a single A. hartigii clone across Europe. This low genetic diversity is consistent with predominantly asexual vertical transmission of Ambrosiella cultivars between beetle generations. This clonal agriculture is a remarkable case of convergence with fungus-farming ants, given that both groups have a completely different ecology and evolutionary history. KW - clonal fungiculture KW - ambrosia fungus KW - Ambrosiella KW - vertical transmission KW - symbiosis KW - Xylosandrus KW - Anisandrus KW - asexuality KW - genetic diversity Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-232161 VL - 32 ER - TY - JOUR A1 - Grebinyk, Anna A1 - Grebinyk, Sergii A1 - Prylutska, Svitlana A1 - Ritter, Uwe A1 - Matyshevska, Olga A1 - Dandekar, Thomas A1 - Frohme, Marcus T1 - C60 fullerene accumulation in human leukemic cells and perspectives of LED-mediated photodynamic therapy JF - Free Radical Biology and Medicine N2 - Recent progress in nanobiotechnology has attracted interest to a biomedical application of the carbon nanostructure C60 fullerene since it possesses a unique structure and versatile biological activity. C60 fullerene potential application in the frame of cancer photodynamic therapy (PDT) relies on rapid development of new light sources as well as on better understanding of the fullerene interaction with cells. The aim of this study was to analyze C60 fullerene effects on human leukemic cells (CCRF-CEM) in combination with high power single chip light-emitting diodes (LEDs) light irradiation of different wavelengths: ultraviolet (UV, 365 nm), violet (405 nm), green (515 nm) and red (632 nm). The time-dependent accumulation of fullerene C60 in CCRF-CEM cells up to 250 ng/106 cells at 24 h with predominant localization within mitochondria was demonstrated with immunocytochemical staining and liquid chromatography mass spectrometry. In a cell viability assay we studied photoexcitation of the accumulated C60 nanostructures with ultraviolet or violet LEDs and could prove that significant phototoxic effects did arise. A less pronounced C60 fullerene phototoxic effect was observed after irradiation with green, and no effect was detected with red light. A C60 fullerene photoactivation with violet light induced substantial ROS generation and apoptotic cell death, confirmed by caspase3/7 activation and plasma membrane phosphatidylserine externalization. Our work proved C60 fullerene ability to induce apoptosis of leukemic cells after photoexcitation with high power single chip 405 nm LED as a light source. This underlined the potential for application of C60 nanostructure as a photosensitizer for anticancer therapy. KW - C-60 fullerene KW - photodanamic therapy KW - LEDs KW - leukemic cells KW - immunocytochemistry KW - HPLC-ESI-MS KW - apoptosis Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228245 VL - 124 ER - TY - JOUR A1 - Link, Jana A1 - Paouneskou, Dimitra A1 - Velkova, Maria A1 - Daryabeigi, Anahita A1 - Laos, Triin A1 - Labella, Sara A1 - Barroso, Consuelo A1 - Pacheco Piñol, Sarai A1 - Montoya, Alex A1 - Kramer, Holger A1 - Woglar, Alexander A1 - Baudrimont, Antoine A1 - Markert, Sebastian Mathias A1 - Stigloher, Christian A1 - Martinez-Perez, Enrique A1 - Dammermann, Alexander A1 - Alsheimer, Manfred A1 - Zetka, Monique A1 - Jantsch, Verena T1 - Transient and Partial Nuclear Lamina Disruption Promotes Chromosome Movement in Early Meiotic Prophase JF - Developmental Cell N2 - Meiotic chromosome movement is important for the pairwise alignment of homologous chromosomes, which is required for correct chromosome segregation. Movement is driven by cytoplasmic forces, transmitted to chromosome ends by nuclear membrane-spanning proteins. In animal cells, lamins form a prominent scaffold at the nuclear periphery, yet the role lamins play in meiotic chromosome movement is unclear. We show that chromosome movement correlates with reduced lamin association with the nuclear rim, which requires lamin phosphorylation at sites analogous to those that open lamina network crosslinks in mitosis. Failure to remodel the lamina results in delayed meiotic entry, altered chromatin organization, unpaired or interlocked chromosomes, and slowed chromosome movement. The remodeling kinases are delivered to lamins via chromosome ends coupled to the nuclear envelope, potentially enabling crosstalk between the lamina and chromosomal events. Thus, opening the lamina network plays a role in modulating contacts between chromosomes and the nuclear periphery during meiosis. KW - meiosis KW - C. elegans KW - chromosome movement KW - chromosome pairing KW - nuclear envelope KW - lamin Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-236901 VL - 45 ER - TY - JOUR A1 - Becher, Isabelle A1 - Andrés-Pons, Amparo A1 - Romanov, Natalie A1 - Stein, Frank A1 - Schramm, Maike A1 - Baudin, Florence A1 - Helm, Dominic A1 - Kurzawa, Nils A1 - Mateus, André A1 - Mackmull, Marie-Therese A1 - Typas, Athanasios A1 - Müller, Christoph W. A1 - Bork, Peer A1 - Beck, Martin A1 - Savitski, Mikhail M. T1 - Pervasive Protein Thermal Stability Variation during the Cell Cycle JF - Cell N2 - Quantitative mass spectrometry has established proteome-wide regulation of protein abundance and post-translational modifications in various biological processes. Here, we used quantitative mass spectrometry to systematically analyze the thermal stability and solubility of proteins on a proteome-wide scale during the eukaryotic cell cycle. We demonstrate pervasive variation of these biophysical parameters with most changes occurring in mitosis and G1. Various cellular pathways and components vary in thermal stability, such as cell-cycle factors, polymerases, and chromatin remodelers. We demonstrate that protein thermal stability serves as a proxy for enzyme activity, DNA binding, and complex formation in situ. Strikingly, a large cohort of intrinsically disordered and mitotically phosphorylated proteins is stabilized and solubilized in mitosis, suggesting a fundamental remodeling of the biophysical environment of the mitotic cell. Our data represent a rich resource for cell, structural, and systems biologists interested in proteome regulation during biological transitions. KW - thermal proteome profiling KW - cell cycle KW - proteomics Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-221565 VL - 173 ER - TY - JOUR A1 - Too, Chin Chin A1 - Keller, Alexander A1 - Sickel, Wiebke A1 - Lee, Sui Mae A1 - Yule, Catherine M. T1 - Microbial Community Structure in a Malaysian Tropical Peat Swamp Forest: The Influence of Tree Species and Depth JF - Frontiers in Microbiology N2 - Tropical peat swamp forests sequester globally significant stores of carbon in deep layers of waterlogged, anoxic, acidic and nutrient-depleted peat. The roles of microbes in supporting these forests through the formation of peat, carbon sequestration and nutrient cycling are virtually unknown. This study investigated physicochemical peat properties and microbial diversity between three dominant tree species: Shorea uliginosa (Dipterocarpaceae), Koompassia malaccensis (legumes associated with nitrogen-fixing bacteria), Eleiodoxa conferta (palm) and depths (surface, 45 and 90 cm) using microbial 16S rRNA gene amplicon sequencing. Water pH, oxygen, nitrogen, phosphorus, total phenolic contents and C/N ratio differed significantly between depths, but not tree species. Depth also strongly influenced microbial diversity and composition, while both depth and tree species exhibited significant impact on the archaeal communities. Microbial diversity was highest at the surface, where fresh leaf litter accumulates, and nutrient supply is guaranteed. Nitrogen was the core parameter correlating to microbial communities, but the interactive effects from various environmental variables displayed significant correlation to relative abundance of major microbial groups. Proteobacteria was the dominant phylum and the most abundant genus, Rhodoplanes, might be involved in nitrogen fixation. The most abundant methanogens and methanotrophs affiliated, respectively, to families Methanomassiliicoccaceae and Methylocystaceae. Our results demonstrated diverse microbial communities and provide valuable insights on microbial ecology in these extreme ecosystems. KW - tropical peat swamp forest KW - metabarcoding KW - microbial diversity and composition KW - tree species KW - depth KW - methanogens Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-229000 VL - 9 ER - TY - JOUR A1 - Prusty, Bhupesh K. A1 - Gulve, Nitish A1 - Govind, Sheila A1 - Krueger, Gerhard R. F. A1 - Feichtinger, Julia A1 - Larcombe, Lee A1 - Aspinall, Richard A1 - Ablashi, Dharam V. A1 - Toro, Carla T. T1 - Active HHV-6 Infection of Cerebellar Purkinje Cells in Mood Disorders JF - Frontiers in Microbiology N2 - Early-life infections and associated neuroinflammation is incriminated in the pathogenesis of various mood disorders. Infection with human roseoloviruses, HHV-6A and HHV-6B, allows viral latency in the central nervous system and other tissues, which can later be activated causing cognitive and behavioral disturbances. Hence, this study was designed to evaluate possible association of HHV-6A and HHV-6B activation with three different groups of psychiatric patients. DNA qPCR, immunofluorescence and FISH studies were carried out in post-mortem posterior cerebellum from 50 cases each of bipolar disorder (BPD), schizophrenia, 15 major depressive disorder (MDD) and 50 appropriate control samples obtained from two well-known brain collections (Stanley Medical Research Institute). HHV-6A and HHV-6B late proteins (indicating active infection) and viral DNA were detected more frequently (p < 0.001 for each virus) in human cerebellum in MDD and BPD relative to controls. These roseolovirus proteins and DNA were found less frequently in schizophrenia cases. Active HHV-6A and HHV-6B infection in cerebellar Purkinje cells were detected frequently in BPD and MDD cases. Furthermore, we found a significant association of HHV-6A infection with reduced Purkinje cell size, suggesting virus-mediated abnormal Purkinje cell function in these disorders. Finally, gene expression analysis of cerebellar tissue revealed changes in pathways reflecting an inflammatory response possibly to HHV-6A infection. Our results provide molecular evidence to support a role for active HHV-6A and HHV-6B infection in BPD and MDD. KW - HHV-6 KW - bipolar disorder KW - schizophrenia KW - major depressive disorder KW - Purkinje cells Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-369222 VL - 9 ER - TY - JOUR A1 - Wegert, Jenny A1 - Vokuhl, Christian A1 - Collord, Grace A1 - Del Castillo Velasco-Herrera, Martin A1 - Farndon, Sarah J. A1 - Guzzo, Charlotte A1 - Jorgensen, Mette A1 - Anderson, John A1 - Slater, Olga A1 - Duncan, Catriona A1 - Bausenwein, Sabrina A1 - Streitenberger, Heike A1 - Ziegler, Barbara A1 - Furtwängler, Rhoikos A1 - Graf, Norbert A1 - Stratton, Michael R. A1 - Campbell, Peter J. A1 - Jones, David TW A1 - Koelsche, Christian A1 - Pfister, Stefan M. A1 - Mifsud, William A1 - Sebire, Neil A1 - Sparber-Sauer, Monika A1 - Koscielniak, Ewa A1 - Rosenwald, Andreas A1 - Gessler, Manfred A1 - Behjati, Sam T1 - Recurrent intragenic rearrangements of EGFR and BRAF in soft tissue tumors of infants JF - Nature Communications N2 - Soft tissue tumors of infancy encompass an overlapping spectrum of diseases that pose unique diagnostic and clinical challenges. We studied genomes and transcriptomes of cryptogenic congenital mesoblastic nephroma (CMN), and extended our findings to five anatomically or histologically related soft tissue tumors: infantile fibrosarcoma (IFS), nephroblastomatosis, Wilms tumor, malignant rhabdoid tumor, and clear cell sarcoma of the kidney. A key finding is recurrent mutation of EGFR in CMN by internal tandem duplication of the kinase domain, thus delineating CMN from other childhood renal tumors. Furthermore, we identify BRAF intragenic rearrangements in CMN and IFS. Collectively these findings reveal novel diagnostic markers and therapeutic strategies and highlight a prominent role of isolated intragenic rearrangements as drivers of infant tumors. KW - cancer KW - genetics Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-233446 VL - 9 ER - TY - JOUR A1 - Vujanić, Gordan M. A1 - Gessler, Manfred A1 - Ooms, Ariadne H. A. G. A1 - Collini, Paola A1 - Coulomb-l'Hermine, Aurore A1 - D'Hooghe, Ellen A1 - de Krijger, Ronald R. A1 - Perotti, Daniela A1 - Pritchard-Jones, Kathy A1 - Vokuhl, Christian A1 - van den Heuvel-Eibrink, Marry M. A1 - Graf, Norbert T1 - The UMBRELLA SIOP–RTSG 2016 Wilms tumour pathology and molecular biology protocol JF - Nature Reviews Urology N2 - On the basis of the results of previous national and international trials and studies, the Renal Tumour Study Group of the International Society of Paediatric Oncology (SIOP–RTSG) has developed a new study protocol for paediatric renal tumours: the UMBRELLA SIOP–RTSG 2016 protocol (the UMBRELLA protocol). Currently, the overall outcomes of patients with Wilms tumour are excellent, but subgroups with poor prognosis and increased relapse rates still exist. The identification of these subgroups is of utmost importance to improve treatment stratification, which might lead to reduction of the direct and late effects of chemotherapy. The UMBRELLA protocol aims to validate new prognostic factors, such as blastemal tumour volume and molecular markers, to further improve outcome. To achieve this aim, large, international, high-quality databases are needed, which dictate optimization and international harmonization of specimen handling and comprehensive sampling of biological material, refine definitions and improve logistics for expert review. To promote broad implementation of the UMBRELLA protocol, the updated SIOP–RTSG pathology and molecular biology protocol for Wilms tumours has been outlined, which is a consensus from the SIOP–RTSG pathology panel. KW - molecular biology KW - paediatric cancer KW - pathology KW - renal cancer Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-233265 VL - 15 ER - TY - JOUR A1 - Sommerfeld, Andreas A1 - Senf, Cornelius A1 - Buma, Brian A1 - D'Amato, Anthony W. A1 - Després, Tiphaine A1 - Díaz-Hormazábal, Ignacio A1 - Fraver, Shawn A1 - Frelich, Lee E. A1 - Gutiérrez, Álvaro G. A1 - Hart, Sarah J. A1 - Harvey, Brian J. A1 - He, Hong S. A1 - Hlásny, Tomáš A1 - Holz, Andrés A1 - Kitzberger, Thomas A1 - Kulakowski, Dominik A1 - Lindenmayer, David A1 - Mori, Akira S. A1 - Müller, Jörg A1 - Paritsis, Juan A1 - Perry, George L. W. A1 - Stephens, Scott L. A1 - Svoboda, Miroslav A1 - Turner, Monica G. A1 - Veblen, Thomas T. A1 - Seidl, Rupert T1 - Patterns and drivers of recent disturbances across the temperate forest biome JF - Nature Communications N2 - Increasing evidence indicates that forest disturbances are changing in response to global change, yet local variability in disturbance remains high. We quantified this considerable variability and analyzed whether recent disturbance episodes around the globe were consistently driven by climate, and if human influence modulates patterns of forest disturbance. We combined remote sensing data on recent (2001–2014) disturbances with in-depth local information for 50 protected landscapes and their surroundings across the temperate biome. Disturbance patterns are highly variable, and shaped by variation in disturbance agents and traits of prevailing tree species. However, high disturbance activity is consistently linked to warmer and drier than average conditions across the globe. Disturbances in protected areas are smaller and more complex in shape compared to their surroundings affected by human land use. This signal disappears in areas with high recent natural disturbance activity, underlining the potential of climate-mediated disturbance to transform forest landscapes. KW - forest ecology KW - forestry Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-239157 VL - 9 ER - TY - JOUR A1 - Snaebjornsson, Marteinn T A1 - Schulze, Almut T1 - Non-canonical functions of enzymes facilitate cross-talk between cell metabolic and regulatory pathways JF - Experimental & Molecular Medicine N2 - The metabolic rewiring that occurs during cell transformation is a hallmark of cancer. It is diverse in different cancers as it reflects different combinations of oncogenic drivers, tumor suppressors, and the microenvironment. Metabolic rewiring is essential to cancer as it enables uncontrolled proliferation and adaptation to the fluctuating availability of nutrients and oxygen caused by poor access to the vasculature due to tumor growth and a foreign microenvironment encountered during metastasis. Increasing evidence now indicates that the metabolic state in cancer cells also plays a causal role in tumor growth and metastasis, for example through the action of oncometabolites, which modulate cell signaling and epigenetic pathways to promote malignancy. In addition to altering the metabolic state in cancer cells, some multifunctional enzymes possess non-metabolic functions that also contribute to cell transformation. Some multifunctional enzymes that are highly expressed in cancer, such as pyruvate kinase M2 (PKM2), have non-canonical functions that are co-opted by oncogenic signaling to drive proliferation and inhibit apoptosis. Other multifunctional enzymes that are frequently downregulated in cancer, such as fructose-bisphosphatase 1 (FBP1), are tumor suppressors, directly opposing mitogenic signaling via their non-canonical functions. In some cases, the enzymatic and non-canonical roles of these enzymes are functionally linked, making the modulation of non-metabolic cellular processes dependent on the metabolic state of the cell. KW - cancer metabolism Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-238763 VL - 50 ER - TY - JOUR A1 - Selkrig, Joel A1 - Mohammad, Farhan A1 - Ng, Soon Hwee A1 - Chua, Jia Yi A1 - Tumkaya, Tayfun A1 - Ho, Joses A1 - Chiang, Yin Ning A1 - Rieger, Dirk A1 - Pettersson, Sven A1 - Helfrich-Förster, Charlotte A1 - Yew, Joanne Y. A1 - Claridge-Chang, Adam T1 - The Drosophila microbiome has a limited influence on sleep, activity, and courtship behaviors JF - Scientific Reports N2 - In animals, commensal microbes modulate various physiological functions, including behavior. While microbiota exposure is required for normal behavior in mammals, it is not known how widely this dependency is present in other animal species. We proposed the hypothesis that the microbiome has a major influence on the behavior of the vinegar fly (Drosophila melanogaster), a major invertebrate model organism. Several assays were used to test the contribution of the microbiome on some well-characterized behaviors: defensive behavior, sleep, locomotion, and courtship in microbe-bearing, control flies and two generations of germ-free animals. None of the behaviors were largely influenced by the absence of a microbiome, and the small or moderate effects were not generalizable between replicates and/or generations. These results refute the hypothesis, indicating that the Drosophila microbiome does not have a major influence over several behaviors fundamental to the animal’s survival and reproduction. The impact of commensal microbes on animal behaviour may not be broadly conserved. KW - behavioural ecology KW - sleep Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-235891 VL - 8 ER - TY - JOUR A1 - Müller, Laura S. M. A1 - Cosentino, Raúl O. A1 - Förstner, Konrad U. A1 - Guizetti, Julien A1 - Wedel, Carolin A1 - Kaplan, Noam A1 - Janzen, Christian J. A1 - Arampatzi, Panagiota A1 - Vogel, Jörg A1 - Steinbiss, Sascha A1 - Otto, Thomas D. A1 - Saliba, Antoine-Emmanuel A1 - Sebra, Robert P. A1 - Siegel, T. Nicolai T1 - Genome organization and DNA accessibility control antigenic variation in trypanosomes JF - Nature N2 - Many evolutionarily distant pathogenic organisms have evolved similar survival strategies to evade the immune responses of their hosts. These include antigenic variation, through which an infecting organism prevents clearance by periodically altering the identity of proteins that are visible to the immune system of the host1. Antigenic variation requires large reservoirs of immunologically diverse antigen genes, which are often generated through homologous recombination, as well as mechanisms to ensure the expression of one or very few antigens at any given time. Both homologous recombination and gene expression are affected by three-dimensional genome architecture and local DNA accessibility2,3. Factors that link three-dimensional genome architecture, local chromatin conformation and antigenic variation have, to our knowledge, not yet been identified in any organism. One of the major obstacles to studying the role of genome architecture in antigenic variation has been the highly repetitive nature and heterozygosity of antigen-gene arrays, which has precluded complete genome assembly in many pathogens. Here we report the de novo haplotype-specific assembly and scaffolding of the long antigen-gene arrays of the model protozoan parasite Trypanosoma brucei, using long-read sequencing technology and conserved features of chromosome folding4. Genome-wide chromosome conformation capture (Hi-C) reveals a distinct partitioning of the genome, with antigen-encoding subtelomeric regions that are folded into distinct, highly compact compartments. In addition, we performed a range of analyses—Hi-C, fluorescence in situ hybridization, assays for transposase-accessible chromatin using sequencing and single-cell RNA sequencing—that showed that deletion of the histone variants H3.V and H4.V increases antigen-gene clustering, DNA accessibility across sites of antigen expression and switching of the expressed antigen isoform, via homologous recombination. Our analyses identify histone variants as a molecular link between global genome architecture, local chromatin conformation and antigenic variation. KW - histone variants KW - genome architecture KW - single molecule real time (SMRT) KW - brucei genome KW - distance-dependent decay Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224265 VL - 563 ER - TY - JOUR A1 - Kraus, Michael A1 - Grimm, Clemens A1 - Seibel, Jürgen T1 - Reversibility of a Point Mutation Induced Domain Shift: Expanding the Conformational Space of a Sucrose Phosphorylase JF - Scientific Reports N2 - Despite their popularity as enzyme engineering targets structural information about Sucrose Phosphorylases remains scarce. We recently clarified that the Q345F variant of Bifidobacterium adolescentis Sucrose Phosphorylase is able to accept large polyphenolic substrates like resveratrol via a domain shift. Here we present a crystal structure of this variant in a conformation suitable for the accommodation of the donor substrate sucrose in excellent agreement with the wild type structure. Remarkably, this conformation does not feature the previously observed domain shift which is therefore reversible and part of a dynamic process rather than a static phenomenon. This crystallographic snapshot completes our understanding of the catalytic cycle of this useful variant and will allow for a more rational design of further generations of Sucrose Phosphorylase variants. KW - biocatalysis KW - X-ray crystallography Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224845 VL - 8 ER - TY - JOUR A1 - Hines, Rochelle M. A1 - Maric, Hans Michael A1 - Hines, Dustin J. A1 - Modgil, Amit A1 - Panzanelli, Patrizia A1 - Nakamura, Yasuko A1 - Nathanson, Anna J. A1 - Cross, Alan A1 - Deeb, Tarek A1 - Brandon, Nicholas J. A1 - Davies, Paul A1 - Fritschy, Jean-Marc A1 - Schindelin, Hermann A1 - Moss, Stephen J. T1 - Developmental seizures and mortality result from reducing GABAA receptor α2-subunit interaction with collybistin JF - Nature Communications N2 - Fast inhibitory synaptic transmission is mediated by γ-aminobutyric acid type A receptors (GABAARs) that are enriched at functionally diverse synapses via mechanisms that remain unclear. Using isothermal titration calorimetry and complementary methods we demonstrate an exclusive low micromolar binding of collybistin to the α2-subunit of GABAARs. To explore the biological relevance of collybistin-α2-subunit selectivity, we generate mice with a mutation in the α2-subunit-collybistin binding region (Gabra2-1). The mutation results in loss of a distinct subset of inhibitory synapses and decreased amplitude of inhibitory synaptic currents. Gabra2–1 mice have a striking phenotype characterized by increased susceptibility to seizures and early mortality. Surviving Gabra2-1 mice show anxiety and elevations in electroencephalogram δ power, which are ameliorated by treatment with the α2/α3-selective positive modulator, AZD7325. Taken together, our results demonstrate an α2-subunit selective binding of collybistin, which plays a key role in patterned brain activity, particularly during development. KW - cellular neuroscience KW - ion channels in the nervous system KW - neurotransmitters KW - synaptic development Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-320719 VL - 9 ER - TY - JOUR A1 - Hennrich, Marco L. A1 - Romanov, Natalie A1 - Horn, Patrick A1 - Jaeger, Samira A1 - Eckstein, Volker A1 - Steeples, Violetta A1 - Ye, Fei A1 - Ding, Ximing A1 - Poisa-Beiro, Laura A1 - Mang, Ching Lai A1 - Lang, Benjamin A1 - Boultwood, Jacqueline A1 - Luft, Thomas A1 - Zaugg, Judith B. A1 - Pellagatti, Andrea A1 - Bork, Peer A1 - Aloy, Patrick A1 - Gavin, Anne-Claude A1 - Ho, Anthony D. T1 - Cell-specific proteome analyses of human bone marrow reveal molecular features of age-dependent functional decline JF - Nature Communications N2 - Diminishing potential to replace damaged tissues is a hallmark for ageing of somatic stem cells, but the mechanisms remain elusive. Here, we present proteome-wide atlases of age-associated alterations in human haematopoietic stem and progenitor cells (HPCs) and five other cell populations that constitute the bone marrow niche. For each, the abundance of a large fraction of the ~12,000 proteins identified is assessed in 59 human subjects from different ages. As the HPCs become older, pathways in central carbon metabolism exhibit features reminiscent of the Warburg effect, where glycolytic intermediates are rerouted towards anabolism. Simultaneously, altered abundance of early regulators of HPC differentiation reveals a reduced functionality and a bias towards myeloid differentiation. Ageing causes alterations in the bone marrow niche too, and diminishes the functionality of the pathways involved in HPC homing. The data represent a valuable resource for further analyses, and for validation of knowledge gained from animal models. KW - ageing KW - haematopoietic stem cells KW - mesenchymal stem cells Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-319877 VL - 9 ER - TY - JOUR A1 - Heil, Hannah S. A1 - Schreiber, Benjamin A1 - Götz, Ralph A1 - Emmerling, Monika A1 - Dabauvalle, Marie-Christine A1 - Krohne, Georg A1 - Höfling, Sven A1 - Kamp, Martin A1 - Sauer, Markus A1 - Heinze, Katrin G. T1 - Sharpening emitter localization in front of a tuned mirror JF - Light: Science & Applications N2 - Single-molecule localization microscopy (SMLM) aims for maximized precision and a high signal-to-noise ratio1. Both features can be provided by placing the emitter in front of a metal-dielectric nanocoating that acts as a tuned mirror2,3,4. Here, we demonstrate that a higher photon yield at a lower background on biocompatible metal-dielectric nanocoatings substantially improves SMLM performance and increases the localization precision by up to a factor of two. The resolution improvement relies solely on easy-to-fabricate nanocoatings on standard glass coverslips and is spectrally and spatially tunable by the layer design and wavelength, as experimentally demonstrated for dual-color SMLM in cells. KW - imaging and sensing KW - super-resolution microscopy Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228080 VL - 7 ER - TY - JOUR A1 - Gröbner, Susanne N. A1 - Worst, Barbara C. A1 - Weischenfeldt, Joachim A1 - Buchhalter, Ivo A1 - Kleinheinz, Kortine A1 - Rudneva, Vasilisa A. A1 - Johann, Pascal D. A1 - Balasubramanian, Gnana Prakash A1 - Segura-Wang, Maia A1 - Brabetz, Sebastian A1 - Bender, Sebastian A1 - Hutter, Barbara A1 - Sturm, Dominik A1 - Pfaff, Elke A1 - Hübschmann, Daniel A1 - Zipprich, Gideon A1 - Heinold, Michael A1 - Eils, Jürgen A1 - Lawerenz, Christian A1 - Erkek, Serap A1 - Lambo, Sander A1 - Waszak, Sebastian A1 - Blattmann, Claudia A1 - Borkhardt, Arndt A1 - Kuhlen, Michaela A1 - Eggert, Angelika A1 - Fulda, Simone A1 - Gessler, Manfred A1 - Wegert, Jenny A1 - Kappler, Roland A1 - Baumhoer, Daniel A1 - Stefan, Burdach A1 - Kirschner-Schwabe, Renate A1 - Kontny, Udo A1 - Kulozik, Andreas E. A1 - Lohmann, Dietmar A1 - Hettmer, Simone A1 - Eckert, Cornelia A1 - Bielack, Stefan A1 - Nathrath, Michaela A1 - Niemeyer, Charlotte A1 - Richter, Günther H. A1 - Schulte, Johannes A1 - Siebert, Reiner A1 - Westermann, Frank A1 - Molenaar, Jan J. A1 - Vassal, Gilles A1 - Witt, Hendrik A1 - Burkhardt, Birgit A1 - Kratz, Christian P. A1 - Witt, Olaf A1 - van Tilburg, Cornelis M. A1 - Kramm, Christof M. A1 - Fleischhack, Gudrun A1 - Dirksen, Uta A1 - Rutkowski, Stefan A1 - Frühwald, Michael A1 - Hoff, Katja von A1 - Wolf, Stephan A1 - Klingebeil, Thomas A1 - Koscielniak, Ewa A1 - Landgraf, Pablo A1 - Koster, Jan A1 - Resnick, Adam C. A1 - Zhang, Jinghui A1 - Liu, Yanling A1 - Zhou, Xin A1 - Waanders, Angela J. A1 - Zwijnenburg, Danny A. A1 - Raman, Pichai A1 - Brors, Benedikt A1 - Weber, Ursula D. A1 - Northcott, Paul A. A1 - Pajtler, Kristian W. A1 - Kool, Marcel A1 - Piro, Rosario M. A1 - Korbel, Jan O. A1 - Schlesner, Matthias A1 - Eils, Roland A1 - Jones, David T. W. A1 - Lichter, Peter A1 - Chavez, Lukas A1 - Zapatka, Marc A1 - Pfister, Stefan M. T1 - The landscape of genomic alterations across childhood cancers JF - Nature N2 - Pan-cancer analyses that examine commonalities and differences among various cancer types have emerged as a powerful way to obtain novel insights into cancer biology. Here we present a comprehensive analysis of genetic alterations in a pan-cancer cohort including 961 tumours from children, adolescents, and young adults, comprising 24 distinct molecular types of cancer. Using a standardized workflow, we identified marked differences in terms of mutation frequency and significantly mutated genes in comparison to previously analysed adult cancers. Genetic alterations in 149 putative cancer driver genes separate the tumours into two classes: small mutation and structural/copy-number variant (correlating with germline variants). Structural variants, hyperdiploidy, and chromothripsis are linked to TP53 mutation status and mutational signatures. Our data suggest that 7–8% of the children in this cohort carry an unambiguous predisposing germline variant and that nearly 50% of paediatric neoplasms harbour a potentially druggable event, which is highly relevant for the design of future clinical trials. KW - cancer genomics KW - oncogenesis KW - paediatric cancer KW - predictive markers KW - translational research Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-229579 VL - 555 ER - TY - JOUR A1 - Franchini, Paolo A1 - Jones, Julia C. A1 - Xiong, Peiwen A1 - Kneitz, Susanne A1 - Gompert, Zachariah A1 - Warren, Wesley C. A1 - Walter, Ronald B. A1 - Meyer, Axel A1 - Schartl, Manfred T1 - Long-term experimental hybridisation results in the evolution of a new sex chromosome in swordtail fish JF - Nature Communications N2 - The remarkable diversity of sex determination mechanisms known in fish may be fuelled by exceptionally high rates of sex chromosome turnovers or transitions. However, the evolutionary causes and genomic mechanisms underlying this variation and instability are yet to be understood. Here we report on an over 30-year evolutionary experiment in which we tested the genomic consequences of hybridisation and selection between two Xiphophorus fish species with different sex chromosome systems. We find that introgression and imposing selection for pigmentation phenotypes results in the retention of an unexpectedly large maternally derived genomic region. During the hybridisation process, the sex-determining region of the X chromosome from one parental species was translocated to an autosome in the hybrids leading to the evolution of a new sex chromosome. Our results highlight the complexity of factors contributing to patterns observed in hybrid genomes, and we experimentally demonstrate that hybridisation can catalyze rapid evolution of a new sex chromosome. KW - evolutionary genetics KW - experimental evolution KW - genome evolution Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228396 VL - 9 ER - TY - JOUR A1 - Dunce, James M. A1 - Milburn, Amy E. A1 - Gurusaran, Manickam A1 - da Cruz, Irene A1 - Sen, Lee T. A1 - Benavente, Ricardo A1 - Davies, Owen R. T1 - Structural basis of meiotic telomere attachment to the nuclear envelope by MAJIN-TERB2-TERB1 JF - Nature Communications N2 - Meiotic chromosomes undergo rapid prophase movements, which are thought to facilitate the formation of inter-homologue recombination intermediates that underlie synapsis, crossing over and segregation. The meiotic telomere complex (MAJIN, TERB1, TERB2) tethers telomere ends to the nuclear envelope and transmits cytoskeletal forces via the LINC complex to drive these rapid movements. Here, we report the molecular architecture of the meiotic telomere complex through the crystal structure of MAJIN-TERB2, together with light and X-ray scattering studies of wider complexes. The MAJIN-TERB2 2:2 hetero-tetramer binds strongly to DNA and is tethered through long flexible linkers to the inner nuclear membrane and two TRF1-binding 1:1 TERB2-TERB1 complexes. Our complementary structured illumination microscopy studies and biochemical findings reveal a telomere attachment mechanism in which MAJIN-TERB2-TERB1 recruits telomere-bound TRF1, which is then displaced during pachytene, allowing MAJIN-TERB2-TERB1 to bind telomeric DNA and form a mature attachment plate. KW - DNA KW - meiosis KW - proteins KW - super-resolution microscopy KW - X-ray crystallography Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-226416 VL - 9 ER - TY - JOUR A1 - Carradec, Quentin A1 - Pelletier, Eric A1 - Da Silva, Corinne A1 - Alberti, Adriana A1 - Seeleuthner, Yoann A1 - Blanc-Mathieu, Romain A1 - Lima-Mendez, Gipsi A1 - Rocha, Fabio A1 - Tirichine, Leila A1 - Labadie, Karine A1 - Kirilovsky, Amos A1 - Bertrand, Alexis A1 - Engelen, Stefan A1 - Madoui, Mohammed-Amin A1 - Méheust, Raphaël A1 - Poulain, Julie A1 - Romac, Sarah A1 - Richter, Daniel J. A1 - Yoshikawa, Genki A1 - Dimier, Céline A1 - Kandels-Lewis, Stefanie A1 - Picheral, Marc A1 - Searson, Sarah A1 - Jaillon, Olivier A1 - Aury, Jean-Marc A1 - Karsenti, Eric A1 - Sullivan, Matthew B. A1 - Sunagawa, Shinichi A1 - Bork, Peer A1 - Not, Fabrice A1 - Hingamp, Pascal A1 - Raes, Jeroen A1 - Guidi, Lionel A1 - Ogata, Hiroyuki A1 - de Vargas, Colomban A1 - Iudicone, Daniele A1 - Bowler, Chris A1 - Wincker, Patrick T1 - A global ocean atlas of eukaryotic gene JF - Nature Communications N2 - While our knowledge about the roles of microbes and viruses in the ocean has increased tremendously due to recent advances in genomics and metagenomics, research on marine microbial eukaryotes and zooplankton has benefited much less from these new technologies because of their larger genomes, their enormous diversity, and largely unexplored physiologies. Here, we use a metatranscriptomics approach to capture expressed genes in open ocean Tara Oceans stations across four organismal size fractions. The individual sequence reads cluster into 116 million unigenes representing the largest reference collection of eukaryotic transcripts from any single biome. The catalog is used to unveil functions expressed by eukaryotic marine plankton, and to assess their functional biogeography. Almost half of the sequences have no similarity with known proteins, and a great number belong to new gene families with a restricted distribution in the ocean. Overall, the resource provides the foundations for exploring the roles of marine eukaryotes in ocean ecology and biogeochemistry. KW - genomics KW - marine biology KW - microbial ecology KW - water microbiology Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-222250 VL - 9 ER - TY - JOUR A1 - Brunk, Michael A1 - Sputh, Sebastian A1 - Doose, Sören A1 - van de Linde, Sebastian A1 - Terpitz, Ulrich T1 - HyphaTracker: An ImageJ toolbox for time-resolved analysis of spore germination in filamentous fungi JF - Scientific Reports N2 - The dynamics of early fungal development and its interference with physiological signals and environmental factors is yet poorly understood. Especially computational analysis tools for the evaluation of the process of early spore germination and germ tube formation are still lacking. For the time-resolved analysis of conidia germination of the filamentous ascomycete Fusarium fujikuroi we developed a straightforward toolbox implemented in ImageJ. It allows for processing of microscopic acquisitions (movies) of conidial germination starting with drift correction and data reduction prior to germling analysis. From the image time series germling related region of interests (ROIs) are extracted, which are analysed for their area, circularity, and timing. ROIs originating from germlings crossing other hyphae or the image boundaries are omitted during analysis. Each conidium/hypha is identified and related to its origin, thus allowing subsequent categorization. The efficiency of HyphaTracker was proofed and the accuracy was tested on simulated germlings at different signal-to-noise ratios. Bright-field microscopic images of conidial germination of rhodopsin-deficient F. fujikuroi mutants and their respective control strains were analysed with HyphaTracker. Consistent with our observation in earlier studies the CarO deficient mutant germinated earlier and grew faster than other, CarO expressing strains. KW - bioinformatics KW - cell growth KW - fungal biology KW - microscopy Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-221691 VL - 8 ER - TY - JOUR A1 - Albrecht, Jörg A1 - Classen, Alice A1 - Vollstädt, Maximilian G.R. A1 - Mayr, Antonia A1 - Mollel, Neduvoto P. A1 - Schellenberger Costa, David A1 - Dulle, Hamadi I. A1 - Fischer, Markus A1 - Hemp, Andreas A1 - Howell, Kim M. A1 - Kleyer, Michael A1 - Nauss, Thomas A1 - Peters, Marcell K. A1 - Tschapka, Marco A1 - Steffan-Dewenter, Ingolf A1 - Böhning-Gaese, Katrin A1 - Schleuning, Matthias T1 - Plant and animal functional diversity drive mutualistic network assembly across an elevational gradient JF - Nature Communications N2 - Species' functional traits set the blueprint for pair-wise interactions in ecological networks. Yet, it is unknown to what extent the functional diversity of plant and animal communities controls network assembly along environmental gradients in real-world ecosystems. Here we address this question with a unique dataset of mutualistic bird-fruit, bird-flower and insect-flower interaction networks and associated functional traits of 200 plant and 282 animal species sampled along broad climate and land-use gradients on Mt. Kilimanjaro. We show that plant functional diversity is mainly limited by precipitation, while animal functional diversity is primarily limited by temperature. Furthermore, shifts in plant and animal functional diversity along the elevational gradient control the niche breadth and partitioning of the respective other trophic level. These findings reveal that climatic constraints on the functional diversity of either plants or animals determine the relative importance of bottom-up and top-down control in plant-animal interaction networks. KW - Traits-Environment Relationships KW - Species Traits KW - Ecological Networks KW - 4TH-Corner Problem KW - Multiple Traits KW - Bottom-up KW - Biodiversity KW - Community ecology KW - Ecological networks KW - Ecology KW - Ecosystem ecology Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-221056 VL - 9 ER - TY - JOUR A1 - Coelho, Luis Pedro A1 - Kultima, Jens Roat A1 - Costea, Paul Igor A1 - Fournier, Coralie A1 - Pan, Yuanlong A1 - Czarnecki-Maulden, Gail A1 - Hayward, Matthew Robert A1 - Forslund, Sofia K. A1 - Schmidt, Thomas Sebastian Benedikt A1 - Descombes, Patrick A1 - Jackson, Janet R. A1 - Li, Qinghong A1 - Bork, Peer T1 - Similarity of the dog and human gut microbiomes in gene content and response to diet JF - Microbiome N2 - Background Gut microbes influence their hosts in many ways, in particular by modulating the impact of diet. These effects have been studied most extensively in humans and mice. In this work, we used whole genome metagenomics to investigate the relationship between the gut metagenomes of dogs, humans, mice, and pigs. Results We present a dog gut microbiome gene catalog containing 1,247,405 genes (based on 129 metagenomes and a total of 1.9 terabasepairs of sequencing data). Based on this catalog and taxonomic abundance profiling, we show that the dog microbiome is closer to the human microbiome than the microbiome of either pigs or mice. To investigate this similarity in terms of response to dietary changes, we report on a randomized intervention with two diets (high-protein/low-carbohydrate vs. lower protein/higher carbohydrate). We show that diet has a large and reproducible effect on the dog microbiome, independent of breed or sex. Moreover, the responses were in agreement with those observed in previous human studies. Conclusions We conclude that findings in dogs may be predictive of human microbiome results. In particular, a novel finding is that overweight or obese dogs experience larger compositional shifts than lean dogs in response to a high-protein diet. KW - microbiome KW - diet KW - metagenomics KW - dog microbiome KW - human microbiome KW - mouse microbiome KW - pig microbiome Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-223177 VL - 6 ER - TY - JOUR A1 - Ranger, Christopher M. A1 - Biedermann, Peter HW A1 - Phuntumart, Vipaporn A1 - Beligala, Gayathri U. A1 - Ghosh, Satyaki A1 - Palmquist, Debra E. A1 - Mueller, Robert A1 - Barnett, Jenny A1 - Schultz, Peter B. A1 - Reding, Michael E. A1 - Benz, J. Philipp T1 - Symbiont selection via alcohol benefits fungus farming by ambrosia beetles JF - Proceedings of the National Academy of Sciences N2 - Animal-microbe mutualisms are typically maintained by vertical symbiont transmission or partner choice. A third mechanism, screening of high-quality symbionts, has been predicted in theory, but empirical examples are rare. Here we demonstrate that ambrosia beetles rely on ethanol within host trees for promoting gardens of their fungal symbiont and producing offspring. Ethanol has long been known as the main attractant for many of these fungus-farming beetles as they select host trees in which they excavate tunnels and cultivate fungal gardens. More than 300 attacks by Xylosandrus germanus and other species were triggered by baiting trees with ethanol lures, but none of the foundresses established fungal gardens or produced broods unless tree tissues contained in vivo ethanol resulting from irrigation with ethanol solutions. More X. germanus brood were also produced in a rearing substrate containing ethanol. These benefits are a result of increased food supply via the positive effects of ethanol on food-fungus biomass. Selected Ambrosiella and Raffaelea fungal isolates from ethanol-responsive ambrosia beetles profited directly and indirectly by (i) a higher biomass on medium containing ethanol, (ii) strong alcohol dehydrogenase enzymatic activity, and (iii) a competitive advantage over weedy fungal garden competitors (Aspergillus, Penicillium) that are inhibited by ethanol. As ambrosia fungi both detoxify and produce ethanol, they may maintain the selectivity of their alcohol-rich habitat for their own purpose and that of other ethanol-resistant/producing microbes. This resembles biological screening of beneficial symbionts and a potentially widespread, unstudied benefit of alcohol-producing symbionts (e.g., yeasts) in other microbial symbioses. KW - fungus-farming insects KW - plant-insect-microbe interactions KW - symbiosis KW - insect-fungus mutualism KW - host screening Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224953 VL - 115 IS - 17 ER - TY - JOUR A1 - Batzke, Katharina A1 - Büchel, Gabriele A1 - Hansen, Wiebke A1 - Schramm, Alexander T1 - TrkB-target Galectin-1 impairs immune activation and radiation responses in neuroblastoma: implications for tumour therapy JF - International Journal of Molecular Sciences N2 - Galectin-1 (Gal-1) has been described to promote tumour growth by inducing angiogenesis and to contribute to the tumour immune escape. We had previously identified up-regulation of Gal-1 in preclinical models of aggressive neuroblastoma (NB), the most common extracranial tumour of childhood. While Gal-1 did not confer a survival advantage in the absence of exogenous stressors, Gal-1 contributed to enhanced cell migratory and invasive properties. Here, we review these findings and extend them by analyzing Gal-1 mediated effects on immune cell regulation and radiation resistance. In line with previous results, cell autonomous effects as well as paracrine functions contribute to Gal-1 mediated pro-tumourigenic functions. Interfering with Gal-1 functions in vivo will add to a better understanding of the role of the Gal-1 axis in the complex tumour-host interaction during immune-, chemo- and radiotherapy of neuroblastoma. KW - Galectin-1 KW - radiation response KW - neuroblastoma Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-285097 SN - 1422-0067 VL - 19 IS - 3 ER - TY - JOUR A1 - Adam, Alexander A1 - Deimel, Stephan A1 - Pardo-Medina, Javier A1 - García-Martínez, Jorge A1 - Konte, Tilen A1 - Limón, M. Carmen A1 - Avalos, Javier A1 - Terpitz, Ulrich T1 - Protein activity of the \(Fusarium\) \(fujikuroi\) rhodopsins CarO and OpsA and their relation to fungus−plant interaction JF - International Journal of Molecular Sciences N2 - Fungi possess diverse photosensory proteins that allow them to perceive different light wavelengths and to adapt to changing light conditions in their environment. The biological and physiological roles of the green light-sensing rhodopsins in fungi are not yet resolved. The rice plant pathogen Fusarium fujikuroi exhibits two different rhodopsins, CarO and OpsA. CarO was previously characterized as a light-driven proton pump. We further analyzed the pumping behavior of CarO by patch-clamp experiments. Our data show that CarO pumping activity is strongly augmented in the presence of the plant hormone indole-3-acetic acid and in sodium acetate, in a dose-dependent manner under slightly acidic conditions. By contrast, under these and other tested conditions, the Neurospora rhodopsin (NR)-like rhodopsin OpsA did not exhibit any pump activity. Basic local alignment search tool (BLAST) searches in the genomes of ascomycetes revealed the occurrence of rhodopsin-encoding genes mainly in phyto-associated or phytopathogenic fungi, suggesting a possible correlation of the presence of rhodopsins with fungal ecology. In accordance, rice plants infected with a CarO-deficient F. fujikuroi strain showed more severe bakanae symptoms than the reference strain, indicating a potential role of the CarO rhodopsin in the regulation of plant infection by this fungus. KW - fungal rhodopsins KW - CarO KW - OpsA KW - Fusarium fujikuroi KW - Oryza sativa KW - rice–plant infection KW - green light perception KW - indole-3-acetic acid (IAA) KW - bakanae KW - patch-clamp Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-285125 SN - 1422-0067 VL - 19 IS - 1 ER - TY - JOUR A1 - Buellesbach, Jan A1 - Vetter, Sebastian G. A1 - Schmitt, Thomas T1 - Differences in the reliance on cuticular hydrocarbons as sexual signaling and species discrimination cues in parasitoid wasps JF - Frontiers in Zoology N2 - Background Cuticular hydrocarbons (CHC) have been documented to play crucial roles as species- and sex-specific cues in the chemical communication systems of a wide variety of insects. However, whether they are sufficient by themselves as the sole cue triggering sexual behavior as well as preference of con- over heterospecific mating partners is rarely assessed. We conducted behavioral assays in three representative species of parasitoid wasps (Hymenoptera: Pteromalidae) to determine their reliance on CHC as species-specific sexual signaling cues. Results We found a surprising degree of either unspecific or insufficient sexual signaling when CHC are singled out as recognition cues. Most strikingly, the cosmopolitan species Nasonia vitripennis, expected to experience enhanced selection pressure to discriminate against other co-occurring parasitoids, did not discriminate against CHC of a partially sympatric species from another genus, Trichomalopsis sarcophagae. Focusing on the latter species, in turn, it became apparent that CHC are even insufficient as the sole cue triggering conspecific sexual behavior, hinting at the requirement of additional, synergistic sexual cues particularly important in this species. Finally, in the phylogenetically and chemically most divergent species Muscidifurax uniraptor, we intriguingly found both CHC-based sexual signaling as well as species discrimination behavior intact although this species is naturally parthenogenetic with sexual reproduction only occurring under laboratory conditions. Conclusions Our findings implicate a discrepancy in the reliance on and specificity of CHC as sexual cues in our tested parasitioid wasps. CHC profiles were not sufficient for unambiguous discrimination and preference behavior, as demonstrated by clear cross-attraction between some of our tested wasp genera. Moreover, we could show that only in T. sarcophagae, additional behavioral cues need to be present for triggering natural mating behavior, hinting at an interesting shift in signaling hierarchy in this particular species. This demonstrates the importance of integrating multiple, potentially complementary signaling modalities in future studies for a better understanding of their individual contributions to natural sexual communication behavior. KW - chemical communication KW - assortative mating KW - mate recognition KW - prezygotic reproductive isolation KW - speciation KW - Nasonia KW - Trichomalopsis KW - Muscidifurax KW - Pteromalidae KW - Hymenoptera Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-221702 VL - 15 ER - TY - JOUR A1 - Rat, Charlotte A1 - Heiby, Julia C. A1 - Bunz, Jessica P. A1 - Neuweiler, Hannes T1 - Two-step self-assembly of a spider silk molecular clamp JF - Nature Communications N2 - Web spiders synthesize silk fibers of unique strength and extensibility through the controlled self-assembly of protein building blocks, so-called spidroins. The spidroin C-terminal domain is highly conserved and connects two polypeptide chains through formation of an all-helical, intertwined dimer. Here we use contact-induced fluorescence self-quenching and resonance energy transfer in combination with far-UV circular dichroism spectroscopy as three orthogonal structural probes to dissect the mechanism of folding and dimerization of a spidroin C-terminal domain from the major ampullate gland of the nursery web spider Euprosthenops australis. We show that helices forming the dimer core assemble very rapidly and fold on association. Subsequently, peripheral helices fold and dock slowly onto the preformed core. Lability of outer helices facilitates formation of a highly expanded, partially folded dimer. The high end-to-end distance of chain termini in the partially folded dimer suggests an extensibility module that contributes to elasticity of spider silk. KW - Circular dichroism KW - Fluorescence spectroscopy KW - Biokinetics Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225016 VL - 9 ER - TY - JOUR A1 - Rubio-Cosials, Anna A1 - Schulz, Eike C. A1 - Lambertsen, Lotte A1 - Smyshlyaev, Georgy A1 - Rojas-Cordova, Carlos A1 - Forslund, Kristoffer A1 - Karaca, Ezgi A1 - Bebel, Aleksandra A1 - Bork, Peer A1 - Barabas, Orsolya T1 - Transposase-DNA Complex Structures Reveal Mechanisms for Conjugative Transposition of Antibiotic Resistance JF - Cell N2 - Conjugative transposition drives the emergence of multidrug resistance in diverse bacterial pathogens, yet the mechanisms are poorly characterized. The Tn1549 conjugative transposon propagates resistance to the antibiotic vancomycin used for severe drug-resistant infections. Here, we present four high-resolution structures of the conserved Y-transposase of Tn1549 complexed with circular transposon DNA intermediates. The structures reveal individual transposition steps and explain how specific DNA distortion and cleavage mechanisms enable DNA strand exchange with an absolute minimum homology requirement. This appears to uniquely allow Tn916-like conjugative transposons to bypass DNA homology and insert into diverse genomic sites, expanding gene transfer. We further uncover a structural regulatory mechanism that prevents premature cleavage of the transposon DNA before a suitable target DNA is found and generate a peptide antagonist that interferes with the transposase-DNA structure to block transposition. Our results reveal mechanistic principles of conjugative transposition that could help control the spread of antibiotic resistance genes. KW - DNA complex KW - crystallography KW - Tn1549 transposon KW - Tn916-like transposon family KW - conjugative transposition KW - tyrosine recombinase KW - antibiotic resistance KW - gene transfer KW - vancomycin KW - multidrug-resistant bacteria Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-227085 VL - 173 IS - 1 ER - TY - JOUR A1 - Reis, Helena A1 - Schwebs, Marie A1 - Dietz, Sabrina A1 - Janzen, Christian J. A1 - Butter, Falk T1 - TelAP1 links telomere complexes with developmental expression site silencing in African trypanosomes JF - Nucleic Acids Research N2 - During its life cycle, Trypanosoma brucei shuttles between a mammalian host and the tsetse fly vector. In the mammalian host, immune evasion of T. brucei bloodstream form (BSF) cells relies on antigenic variation, which includes monoallelic expression and periodic switching of variant surface glycoprotein (VSG) genes. The active VSG is transcribed from only 1 of the 15 subtelomeric expression sites (ESs). During differentiation from BSF to the insect-resident procyclic form (PCF), the active ES is transcriptionally silenced. We used mass spectrometry-based interactomics to determine the composition of telomere protein complexes in T. brucei BSF and PCF stages to learn more about the structure and functions of telomeres in trypanosomes. Our data suggest a different telomere complex composition in the two forms of the parasite. One of the novel telomere-associated proteins, TelAP1, forms a complex with telomeric proteins TbTRF, TbRAP1 and TbTIF2 and influences ES silencing kinetics during developmental differentiation. KW - Gene Regulation KW - Chromatin and Epigenetics Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225180 VL - 46 IS - 6 ER - TY - JOUR A1 - Ribitsch, Iris A1 - Peham, Christian A1 - Ade, Nicole A1 - Duerr, Julia A1 - Handschuh, Stephan A1 - Schramel, Johannes Peter A1 - Vogl, Claus A1 - Walles, Heike A1 - Egerbacher, Monika A1 - Jenner, Florian T1 - Structure-Function relationships of equine menisci JF - PLoS ONE N2 - Meniscal pathologies are among the most common injuries of the femorotibial joint in both human and equine patients. Pathological forces and ensuing injuries of the cranial horn of the equine medial meniscus are considered analogous to those observed in the human posterior medial horn. Biomechanical properties of human menisci are site-and depth-specific. However, the influence of equine meniscus topography and composition on its biomechanical properties is yet unknown. A better understanding of equine meniscus composition and biomechanics could advance not only veterinary therapies for meniscus degeneration or injuries, but also further substantiate the horse as suitable translational animal model for (human) meniscus tissue engineering. Therefore, the aim of this study was to investigate the composition and structure of the equine knee meniscus in a site-and age-specific manner and their relationship with potential site-specific biomechanical properties. The meniscus architecture was investigated histologically. Biomechanical testing included evaluation of the shore hardness (SH), stiffness and energy loss of the menisci. The SH was found to be subjected to both age and site-specific changes, with an overall higher SH of the tibial meniscus surface and increase in SH with age. Stiffness and energy loss showed neither site nor age related significant differences. The macroscopic and histologic similarities between equine and human menisci described in this study, support continued research in this field. KW - Human Medial Meniscus KW - Articular-Cartilage KW - Biomechanical Properties KW - Compressive Properties KW - Human Knee KW - Collagen KW - Injuries KW - Models KW - Repair KW - Osteoarthritis Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225214 VL - 13 IS - 3 ER - TY - JOUR A1 - Scheib, Ulrike A1 - Broser, Matthias A1 - Constantin, Oana M. A1 - Yang, Shang A1 - Gao, Shiqiang A1 - Mukherjee, Shatanik A1 - Stehfest, Katja A1 - Nagel, Georg A1 - Gee, Christine E. A1 - Hegemann, Peter T1 - Rhodopsin-cyclases for photocontrol of cGMP/cAMP and 2.3 Å structure of the adenylyl cyclase domain JF - Nature Communications N2 - The cyclic nucleotides cAMP and cGMP are important second messengers that orchestrate fundamental cellular responses. Here, we present the characterization of the rhodopsinguanylyl cyclase from Catenaria anguillulae (CaRhGC), which produces cGMP in response to green light with a light to dark activity ratio > 1000. After light excitation the putative signaling state forms with tau = 31 ms and decays with tau = 570 ms. Mutations (up to 6) within the nucleotide binding site generate rhodopsin-adenylyl cyclases (CaRhACs) of which the double mutated YFP-CaRhAC (E497K/C566D) is the most suitable for rapid cAMP production in neurons. Furthermore, the crystal structure of the ligand-bound AC domain (2.25 angstrom) reveals detailed information about the nucleotide binding mode within this recently discovered class of enzyme rhodopsin. Both YFP-CaRhGC and YFP-CaRhAC are favorable optogenetic tools for non-invasive, cell-selective, and spatio-temporally precise modulation of cAMP/cGMP with light. KW - Enzymes KW - Molecular biophysics KW - Molecular neuroscience KW - X-ray crystallography Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228517 VL - 9 ER - TY - JOUR A1 - Schenk, Mariela A1 - Mitesser, Oliver A1 - Hovestadt, Thomas A1 - Holzschuh, Andrea T1 - Overwintering temperature and body condition shift emergence dates of spring-emerging solitary bees JF - PeerJ N2 - Solitary bees in seasonal environments must align their life-cycles with favorable environmental conditions and resources; the timing of their emergence is highly fitness relevant. In several bee species, overwintering temperature influences both emergence date and body weight at emergence. High variability in emergence dates among specimens overwintering at the same temperatures suggests that the timing of emergence also depends on individual body conditions. However, possible causes for this variability, such as individual differences in body size or weight, have been rarely studied. In a climate chamber experiment using two spring-emerging mason bees (Osmia cornuta and O. bicornis), we investigated the relationship between temperature, emergence date, body weight, and body size, the last of which is not affected by overwintering temperature. Our study showed that body weight declined during hibernation more strongly in warm than in cold overwintering temperatures. Although bees emerged earlier in warm than in cold overwintering temperatures, at the time of emergence, bees in warm overwintering temperatures had lower body weights than bees in cold overwintering temperatures (exception of male O. cornuta). Among specimens that experienced the same overwintering temperatures, small and light bees emerged later than their larger and heavier conspecifics. Using a simple mechanistic model we demonstrated that spring-emerging solitary bees use a strategic approach and emerge at a date that is most promising for their individual fitness expectations. Our results suggest that warmer overwintering temperatures reduce bee fitness by causing a decrease in body weight at emergence. We showed furthermore that in order to adjust their emergence dates, bees use not only temperature but also their individual body condition as triggers. This may explain differing responses to climate warming within and among bee populations and may have consequences for bee-plant interactions as well as for the persistence of bee populations under climate change. KW - Wild bees KW - Timing KW - Fitness KW - Hibernation KW - Climate change KW - Mechanistic model KW - Osmia KW - Body weight KW - Body size KW - Pollinators Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228544 VL - 6 ER - TY - JOUR A1 - Schenk, Mariela A1 - Krauss, Jochen A1 - Holzschuh, Andrea T1 - Desynchronizations in bee-plant interactions cause severe fitness losses in solitary bees JF - Journal of Animal Ecology N2 - 1. Global warming can disrupt mutualistic interactions between solitary bees and plants when increasing temperature differentially changes the timing of interacting partners. One possible scenario is for insect phenology to advance more rapidly than plant phenology. 2. However, empirical evidence for fitness consequences due to temporal mismatches is lacking for pollinators and it remains unknown if bees have developed strategies to mitigate fitness losses following temporal mismatches. 3. We tested the effect of temporal mismatches on the fitness of three spring-emerging solitary bee species, including one pollen specialist. Using flight cages, we simulated (i) a perfect synchronization (from a bee perspective): bees and flowers occur simultaneously, (ii) a mismatch of 3days and (iii) a mismatch of 6days, with bees occurring earlier than flowers in the latter two cases. 4. A mismatch of 6days caused severe fitness losses in all three bee species, as few bees survived without flowers. Females showed strongly reduced activity and reproductive output compared to synchronized bees. Fitness consequences of a 3-day mismatch were species-specific. Both the early-spring species Osmia cornuta and the mid-spring species Osmia bicornis produced the same number of brood cells after a mismatch of 3days as under perfect synchronization. However, O.cornuta decreased the number of female offspring, whereas O.bicornis spread the brood cells over fewer nests, which may increase offspring mortality, e.g. due to parasitoids. The late-spring specialist Osmia brevicornis produced fewer brood cells even after a mismatch of 3days. Additionally, our results suggest that fitness losses after temporal mismatches are higher during warm than cold springs, as the naturally occurring temperature variability revealed that warm temperatures during starvation decreased the survival rate of O.bicornis. 5. We conclude that short temporal mismatches can cause clear fitness losses in solitary bees. Although our results suggest that bees have evolved species-specific strategies to mitigate fitness losses after temporal mismatches, the bees were not able to completely compensate for impacts on their fitness after temporal mismatches with their food resources. KW - conditional sex allocation KW - emergence KW - mitigation strategies KW - mutualism KW - phenological shift KW - pollination KW - species interactions KW - pollinator interactions KW - climate-change KW - phenological response Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228533 VL - 87 IS - 1 ER - TY - JOUR A1 - Christopher D., Pull A1 - Ugelvig, Line V. A1 - Wiesenhofer, Florian A1 - Anna V., Grasse A1 - Tragust, Simon A1 - Schmitt, Thomas A1 - Brown, Mark JF A1 - Cremer, Sylvia T1 - Destructive disinfection of infected brood prevents systemic disease spread in ant colonies JF - eLIFE N2 - In social groups, infections have the potential to spread rapidly and cause disease outbreaks. Here, we show that in a social insect, the ant Lasius neglectus, the negative consequences of fungal infections (Metarhizium brunneum) can be mitigated by employing an efficient multicomponent behaviour, termed destructive disinfection, which prevents further spread of the disease through the colony. Ants specifically target infected pupae during the pathogens non-contagious incubation period, utilising chemical 'sickness cues' emitted by pupae. They then remove the pupal cocoon, perforate its cuticle and administer antimicrobial poison, which enters the body and prevents pathogen replication from the inside out. Like the immune system of a metazoan body that specifically targets and eliminates infected cells, ants destroy infected brood to stop the pathogen completing its lifecycle, thus protecting the rest of the colony. Hence, in an analogous fashion, the same principles of disease defence apply at different levels of biological organisation. KW - division of labor KW - Fungal cell-walls KW - Leaf cutting ants KW - Metarhizium anisopliae KW - Beauveria bassiana Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-223728 VL - 7 ER - TY - JOUR A1 - Rasa, Santa A1 - Nora-Krukle, Zaiga A1 - Henning, Nina A1 - Eliassen, Eva A1 - Shikova, Evelina A1 - Harrer, Thomas A1 - Scheibenbogen, Carmen A1 - Murovska, Modra A1 - Prusty, Bhupesh K. T1 - Chronic viral infections in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) JF - Journal of Translational Medicine N2 - Background and main text: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex and controversial clinical condition without having established causative factors. Increasing numbers of cases during past decade have created awareness among patients as well as healthcare professionals. Chronic viral infection as a cause of ME/CFS has long been debated. However, lack of large studies involving well-designed patient groups and validated experimental set ups have hindered our knowledge about this disease. Moreover, recent developments regarding molecular mechanism of pathogenesis of various infectious agents cast doubts over validity of several of the past studies. Conclusions: This review aims to compile all the studies done so far to investigate various viral agents that could be associated with ME/CFS. Furthermore, we suggest strategies to better design future studies on the role of viral infections in ME/CFS. KW - ME/CFS KW - Viral infections KW - Biomarkers Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224960 VL - 16 IS - 268 ER - TY - JOUR A1 - Reiling, Sarah J. A1 - Krohne, Georg A1 - Friedrich, Oliver A1 - Geary, Timothy G. A1 - Rohrbach, Petra T1 - Chloroquine exposure triggers distinct cellular responses in sensitive versus resistant Plasmodium falciparum parasites JF - Scientific Reports N2 - Chloroquine (CQ) treatment failure in Plasmodium falciparum parasites has been documented for decades, but the pharmacological explanation of this phenotype is not fully understood. Current concepts attribute CQ resistance to reduced accumulation of the drug at a given external CQ concentration ([CQ] ex) in resistant compared to sensitive parasites. The implication of this explanation is that the mechanisms of CQ-induced toxicity in resistant and sensitive strains are similar once lethal internal concentrations have been reached. To test this hypothesis, we investigated the mechanism of CQ-induced toxicity in CQ-sensitive (CQS) versus CQ-resistant (CQR) parasites by analyzing the time-course of cellular responses in these strains after exposure to varying [CQ] ex as determined in 72 h toxicity assays. Parasite killing was delayed in CQR parasites for up to 10 h compared to CQS parasites when exposed to equipotent [CQ] ex. In striking contrast, brief exposure (1 h) to lethal [CQ] ex in CQS but not CQR parasites caused the appearance of hitherto undescribed hemozoin (Hz)-containing compartments in the parasite cytosol. Hz-containing compartments were very rarely observed in CQR parasites even after CQ exposures sufficient to cause irreversible cell death. These findings challenge current concepts that CQ killing of malaria parasites is solely concentration-dependent, and instead suggest that CQS and CQR strains fundamentally differ in the consequences of CQ exposure. KW - Cellular imaging KW - Parasite development Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225123 VL - 8 IS - 11137 ER - TY - JOUR A1 - Scheer, Ulrich T1 - Boveri's research at the Zoological Station Naples: Rediscovery of his original microscope slides at the University of Würzburg JF - Marine Genomics N2 - Eric Davidson once wrote about Theodor Boveri: "From his own researches, and perhaps most important, his generalized interpretations, derive the paradigms that underlie modern inquiries into the genomic basis of embryogenesis" (Davidson, 1985). As luck would have it, the "primary data" of Boveri's experimental work, namely the microscope slides prepared by him and his wife Marcella during several stays at the Zoological Station in Naples (1901/02, 1911/12 and 1914), have survived at the University of Wurzburg. More than 600 slides exist and despite their age they are in a surprisingly good condition. The slides are labelled and dated in Boveri's handwriting and thus can be assigned to his published experimental work on sea urchin development. The results allowed Boveri to unravel the role of the cell nucleus and its chromosomes in development and inheritance. Here, I present an overview of the slides in the context of Boveri's work along with photographic images of selected specimens taken from the original slides. It is planned to examine the slides in more detail, take high-resolution focal image series of significant specimens and make them online available. KW - Sea urchin development KW - Polyspermy KW - Multipolar mitosis KW - Aneuploidy KW - Merogone experiments KW - Science history Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228453 VL - 40 ER - TY - JOUR A1 - Fujiwara, Yuri A1 - Hermann-Luibl, Christiane A1 - Katsura, Maki A1 - Sekiguchi, Manabu A1 - Ida, Takanori A1 - Helfrich-Förster, Charlotte A1 - Yoshii, Taishi T1 - The CCHamide1 Neuropeptide Expressed in the Anterior Dorsal Neuron 1 Conveys a Circadian Signal to the Ventral Lateral Neurons in Drosophila melanogaster JF - Frontiers in Physiology N2 - The fruit fly Drosophila melanogaster possesses approximately 150 brain clock neurons that control circadian behavioral rhythms. Even though individual clock neurons have self-sustaining oscillators, they interact and synchronize with each other through a network. However, little is known regarding the factors responsible for these network interactions. In this study, we investigated the role of CCHamide1 (CCHa1), a neuropeptide expressed in the anterior dorsal neuron 1 (DN1a), in intercellular communication of the clock neurons. We observed that CCHa1 connects the DN1a clock neurons to the ventral lateral clock neurons (LNv) via the CCHa1 receptor, which is a homolog of the gastrin-releasing peptide receptor playing a role in circadian intercellular communications in mammals. CCHa1 knockout or knockdown flies have a generally low activity level with a special reduction of morning activity. In addition, they exhibit advanced morning activity under light-dark cycles and delayed activity under constant dark conditions, which correlates with an advance/delay of PAR domain Protein 1 (PDP1) oscillations in the small-LNv (s-LNv) neurons that control morning activity. The terminals of the s-LNv neurons show rather high levels of Pigment-dispersing factor (PDF) in the evening, when PDF is low in control flies, suggesting that the knockdown of CCHa1 leads to increased PDF release; PDF signals the other clock neurons and evidently increases the amplitude of their PDP1 cycling. A previous study showed that high-amplitude PDP1 cycling increases the siesta of the flies, and indeed, CCHa1 knockout or knockdown flies exhibit a longer siesta than control flies. The DN1a neurons are known to be receptive to PDF signaling from the s-LNv neurons; thus, our results suggest that the DN1a and s-LNv clock neurons are reciprocally coupled via the neuropeptides CCHa1 and PDF, and this interaction fine-tunes the timing of activity and sleep. KW - circadian clock KW - circadian rhythm KW - CCHamide1 KW - pacemaker neuron KW - neuropeptide KW - pigment-dispersing factor Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-195940 SN - 1664-042X VL - 09 ER - TY - JOUR A1 - Beck, Katherina A1 - Hovhanyan, Anna A1 - Menegazzi, Pamela A1 - Helfrich-Förster, Charlotte A1 - Raabe, Thomas T1 - Drosophila RSK Influences the Pace of the Circadian Clock by Negative Regulation of Protein Kinase Shaggy Activity JF - Frontiers in Molecular Neuroscience N2 - Endogenous molecular circadian clocks drive daily rhythmic changes at the cellular, physiological, and behavioral level for adaptation to and anticipation of environmental signals. The core molecular system consists of autoregulatory feedback loops, where clock proteins inhibit their own transcription. A complex and not fully understood interplay of regulatory proteins influences activity, localization and stability of clock proteins to set the pace of the clock. This study focuses on the molecular function of Ribosomal S6 Kinase (RSK) in the Drosophila melanogaster circadian clock. Mutations in the human rsk2 gene cause Coffin–Lowry syndrome, which is associated with severe mental disabilities. Knock-out studies with Drosophila ortholog rsk uncovered functions in synaptic processes, axonal transport and adult behavior including associative learning and circadian activity. However, the molecular targets of RSK remain elusive. Our experiments provide evidence that RSK acts in the key pace maker neurons as a negative regulator of Shaggy (SGG) kinase activity, which in turn determines timely nuclear entry of the clock proteins Period and Timeless to close the negative feedback loop. Phosphorylation of serine 9 in SGG is mediated by the C-terminal kinase domain of RSK, which is in agreement with previous genetic studies of RSK in the circadian clock but argues against the prevailing view that only the N-terminal kinase domain of RSK proteins carries the effector function. Our data provide a mechanistic explanation how RSK influences the molecular clock and imply SGG S9 phosphorylation by RSK and other kinases as a convergence point for diverse cellular and external stimuli. KW - circadian clock KW - Period KW - Timeless KW - Shaggy kinase KW - RSK KW - Coffin–Lowry syndrome Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-196034 SN - 1662-5099 VL - 11 IS - 122 ER - TY - JOUR A1 - Prusty, Bhupesh K. A1 - Chowdhury, Suvagata R. A1 - Gulve, Nitish A1 - Rudel, Thomas T1 - Peptidase Inhibitor 15 (PI15) Regulates Chlamydial CPAF Activity JF - Frontiers in Cellular and Infection Microbiology N2 - Obligate intracellular pathogenic Chlamydia trachomatis express several serine proteases whose roles in chlamydial development and pathogenicity are not completely understood. The chlamydial protease CPAF is expressed during the replicative phase of the chlamydial developmental cycle and is secreted into the lumen of the Chlamydia-containing vacuole called inclusion. How the secreted protease is activated in the inclusion lumen is currently not fully understood. We have identified human serine peptidase inhibitor PI15 as a potential host factor involved in the regulation of CPAF activation. Silencing expression as well as over expression of PI15 affected normal development of Chlamydia. PI15 was transported into the chlamydial inclusion lumen where it co-localized with CPAF aggregates. We show that PI15 binds to the CPAF zymogen and potentially induces CPAF protease activity at low concentrations. However, at high concentrations PI15 inhibits CPAF activity possibly by blocking its protease domain. Our findings shed light on a new aspect of chlamydial host co-evolution which involves the recruitment of host cell proteins into the inclusion to control the activation of bacterial proteases like CPAF that are important for the normal development of Chlamydia. KW - chlamydia KW - CPAF activation KW - peptidase inhibitor PI15 KW - chlamydial inclusion KW - chlamydia serine proteases Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-196918 SN - 2235-2988 VL - 8 IS - 183 ER - TY - JOUR A1 - Anelli, Viviana A1 - Ordas, Anita A1 - Kneitz, Susanne A1 - Sagredo, Leonel Munoz A1 - Gourain, Victor A1 - Schartl, Manfred A1 - Meijer, Annemarie H. A1 - Mione, Marina T1 - Ras-Induced miR-146a and 193a Target Jmjd6 to Regulate Melanoma Progression JF - Frontiers in Genetics N2 - Ras genes are among the most commonly mutated genes in human cancer; yet our understanding of their oncogenic activity at the molecular mechanistic level is incomplete. To identify downstream events that mediate ras-induced cellular transformation in vivo, we analyzed global microRNA expression in three different models of Ras-induction and tumor formation in zebrafish. Six microRNAs were found increased in Ras-induced melanoma, glioma and in an inducible model of ubiquitous Ras expression. The upregulation of the microRNAs depended on the activation of the ERK and AKT pathways and to a lesser extent, on mTOR signaling. Two Ras-induced microRNAs (miR-146a and 193a) target Jmjd6, inducing downregulation of its mRNA and protein levels at the onset of Ras expression during melanoma development. However, at later stages of melanoma progression, jmjd6 levels were found elevated. The dynamic of Jmjd6 levels during progression of melanoma in the zebrafish model suggests that upregulation of the microRNAs targeting Jmjd6 may be part of an anti-cancer response. Indeed, triple transgenic fish engineered to express a microRNA-resistant Jmjd6 from the onset of melanoma have increased tumor burden, higher infiltration of leukocytes and shorter melanoma-free survival. Increased JMJD6 expression is found in several human cancers, including melanoma, suggesting that the up-regulation of Jmjd6 is a critical event in tumor progression. The following link has been created to allow review of record GSE37015: http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?token=jjcrbiuicyyqgpc&acc=GSE37015. KW - zebrafish KW - cancer models KW - microRNA KW - Jmjd6 KW - ras KW - melanoma KW - miR-146a KW - miR-193a Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-196963 SN - 1664-8021 VL - 9 IS - 675 ER - TY - JOUR A1 - Nadella, Vinod A1 - Mohanty, Aparna A1 - Sharma, Lalita A1 - Yellaboina, Sailu A1 - Mollenkopf, Hans-Joachim A1 - Mazumdar, Varadendra Balaji A1 - Palaparthi, Ramesh A1 - Mylavarapu, Madhavi B. A1 - Maurya, Radheshyam A1 - Kurukuti, Sreenivasulu A1 - Rudel, Thomas A1 - Prakash, Hridayesh T1 - Inhibitors of Apoptosis Protein Antagonists (Smac Mimetic Compounds) Control Polarization of Macrophages during Microbial Challenge and Sterile Inflammatory Responses JF - Frontiers in Immunology N2 - Apoptosis is a physiological cell death process essential for development, tissue homeostasis, and for immune defense of multicellular animals. Inhibitors of apoptosis proteins (IAPs) regulate apoptosis in response to various cellular assaults. Using both genetic and pharmacological approaches we demonstrate here that the IAPs not only support opportunistic survival of intracellular human pathogens like Chlamydia pneumoniae but also control plasticity of iNOS+ M1 macrophage during the course of infection and render them refractory for immune stimulation. Treatment of Th1 primed macrophages with birinapant (IAP-specific antagonist) inhibited NO generation and relevant proteins involved in innate immune signaling. Accordingly, birinapant promoted hypoxia, angiogenesis, and tumor-induced M2 polarization of iNOS+ M1 macrophages. Interestingly, birinapant-driven changes in immune signaling were accompanied with changes in the expression of various proteins involved in the metabolism, and thus revealing the new role of IAPs in immune metabolic reprogramming in committed macrophages. Taken together, our study reveals the significance of IAP targeting approaches (Smac mimetic compounds) for the management of infectious and inflammatory diseases relying on macrophage plasticity. KW - apoptosis KW - macrophages immunobiology KW - inflammation mediators KW - polarization KW - infection KW - hypothalamus Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-197484 SN - 1664-3224 VL - 8 IS - 1792 ER - TY - JOUR A1 - Zielewska-Büttner, Katarzyna A1 - Heurich, Marco A1 - Müller, Jörg A1 - Braunisch, Veronika T1 - Remotely Sensed Single Tree Data Enable the Determination of Habitat Thresholds for the Three-Toed Woodpecker (Picoides tridactylus) JF - Remote Sensing N2 - Forest biodiversity conservation requires precise, area-wide information on the abundance and distribution of key habitat structures at multiple spatial scales. We combined airborne laser scanning (ALS) data with color-infrared (CIR) aerial imagery for identifying individual tree characteristics and quantifying multi-scale habitat requirements using the example of the three-toed woodpecker (Picoides tridactylus) (TTW) in the Bavarian Forest National Park (Germany). This bird, a keystone species of boreal and mountainous forests, is highly reliant on bark beetles dwelling in dead or dying trees. While previous studies showed a positive relationship between the TTW presence and the amount of deadwood as a limiting resource, we hypothesized a unimodal response with a negative effect of very high deadwood amounts and tested for effects of substrate quality. Based on 104 woodpecker presence or absence locations, habitat selection was modelled at four spatial scales reflecting different woodpecker home range sizes. The abundance of standing dead trees was the most important predictor, with an increase in the probability of TTW occurrence up to a threshold of 44–50 dead trees per hectare, followed by a decrease in the probability of occurrence. A positive relationship with the deadwood crown size indicated the importance of fresh deadwood. Remote sensing data allowed both an area-wide prediction of species occurrence and the derivation of ecological threshold values for deadwood quality and quantity for more informed conservation management. KW - deadwood KW - standing deadwood KW - dead tree KW - snags KW - three-toed woodpecker (Picoides tridactylus) KW - habitat suitability model (HSM) KW - habitat requirements KW - airborne laser scanning (ALS) KW - CIR aerial imagery Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-197565 SN - 2072-4292 VL - 10 IS - 12 ER - TY - JOUR A1 - Yanku, Yifat A1 - Bitman-Lotan, Eliya A1 - Zohar, Yaniv A1 - Kurant, Estee A1 - Zilke, Norman A1 - Eilers, Martin A1 - Orian, Amir T1 - Drosophila HUWE1 ubiquitin ligase regulates endoreplication and antagonizes JNK signaling during salivary gland development JF - Cells N2 - The HECT-type ubiquitin ligase HECT, UBA and WWE Domain Containing 1, (HUWE1) regulates key cancer-related pathways, including the Myc oncogene. It affects cell proliferation, stress and immune signaling, mitochondria homeostasis, and cell death. HUWE1 is evolutionarily conserved from Caenorhabditis elegance to Drosophila melanogaster and Humans. Here, we report that the Drosophila ortholog, dHUWE1 (CG8184), is an essential gene whose loss results in embryonic lethality and whose tissue-specific disruption establishes its regulatory role in larval salivary gland development. dHUWE1 is essential for endoreplication of salivary gland cells and its knockdown results in the inability of these cells to replicate DNA. Remarkably, dHUWE1 is a survival factor that prevents premature activation of JNK signaling, thus preventing the disintegration of the salivary gland, which occurs physiologically during pupal stages. This function of dHUWE1 is general, as its inhibitory effect is observed also during eye development and at the organismal level. Epistatic studies revealed that the loss of dHUWE1 is compensated by dMyc proeitn expression or the loss of dmP53. dHUWE1 is therefore a conserved survival factor that regulates organ formation during Drosophila development. KW - HECT KW - HUWE1 KW - ubiquitin KW - salivary gland KW - endoreplication KW - JNK KW - dMyc KW - dmP53 Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-197630 SN - 2073-4409 VL - 7 IS - 10 ER - TY - JOUR A1 - Bencurova, Elena A1 - Gupta, Shishir K. A1 - Sarukhanyan, Edita A1 - Dandekar, Thomas T1 - Identification of antifungal targets based on computer modeling JF - Journal of Fungi N2 - Aspergillus fumigatus is a saprophytic, cosmopolitan fungus that attacks patients with a weak immune system. A rational solution against fungal infection aims to manipulate fungal metabolism or to block enzymes essential for Aspergillus survival. Here we discuss and compare different bioinformatics approaches to analyze possible targeting strategies on fungal-unique pathways. For instance, phylogenetic analysis reveals fungal targets, while domain analysis allows us to spot minor differences in protein composition between the host and fungi. Moreover, protein networks between host and fungi can be systematically compared by looking at orthologs and exploiting information from host–pathogen interaction databases. Further data—such as knowledge of a three-dimensional structure, gene expression data, or information from calculated metabolic fluxes—refine the search and rapidly put a focus on the best targets for antimycotics. We analyzed several of the best targets for application to structure-based drug design. Finally, we discuss general advantages and limitations in identification of unique fungal pathways and protein targets when applying bioinformatics tools. KW - Aspergillus KW - metabolic pathways KW - computational modelling KW - drug design Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-197670 SN - 2309-608X VL - 4 IS - 3 ER - TY - JOUR A1 - Keller, Alexander A1 - Brandel, Annette A1 - Becker, Mira C. A1 - Balles, Rebecca A1 - Abdelmohsen, Usama Ramadan A1 - Ankenbrand, Markus J. A1 - Sickel, Wiebke T1 - Wild bees and their nests host Paenibacillus bacteria with functional potential of avail JF - Microbiome N2 - Background: In previous studies, the gram-positive firmicute genus Paenibacillus was found with significant abundances in nests of wild solitary bees. Paenibacillus larvae is well-known for beekeepers as a severe pathogen causing the fatal honey bee disease American foulbrood, and other members of the genus are either secondary invaders of European foulbrood or considered a threat to honey bees. We thus investigated whether Paenibacillus is a common bacterium associated with various wild bees and hence poses a latent threat to honey bees visiting the same flowers. Results: We collected 202 samples from 82 individuals or nests of 13 bee species at the same location and screened each for Paenibacillus using high-throughput sequencing-based 16S metabarcoding. We then isolated the identified strain Paenibacillus MBD-MB06 from a solitary bee nest and sequenced its genome. We did find conserved toxin genes and such encoding for chitin-binding proteins, yet none specifically related to foulbrood virulence or chitinases. Phylogenomic analysis revealed a closer relationship to strains of root-associated Paenibacillus rather than strains causing foulbrood or other accompanying diseases. We found anti-microbial evidence within the genome, confirmed by experimental bioassays with strong growth inhibition of selected fungi as well as gram-positive and gram-negative bacteria. Conclusions: The isolated wild bee associate Paenibacillus MBD-MB06 is a common, but irregularly occurring part of wild bee microbiomes, present on adult body surfaces and guts and within nests especially in megachilids. It was phylogenetically and functionally distinct from harmful members causing honey bee colony diseases, although it shared few conserved proteins putatively toxic to insects that might indicate ancestral predisposition for the evolution of insect pathogens within the group. By contrast, our strain showed anti-microbial capabilities and the genome further indicates abilities for chitin-binding and biofilm-forming, suggesting it is likely a useful associate to avoid fungal penetration of the bee cuticula and a beneficial inhabitant of nests to repress fungal threats in humid and nutrient-rich environments of wild bee nests. KW - 16S metabarcoding KW - American foulbrood KW - anti-microbial activit KW - bacterial genomics KW - bioassays KW - European foulbrood KW - Paenibacterin KW - phylogenomics KW - bee disease KW - pathogen vector Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177554 VL - 6 IS - 229 ER - TY - JOUR A1 - Ruedenauer, Fabian A. A1 - Wöhrle, Christine A1 - Spaethe, Johannes A1 - Leonhardt, Sara D. T1 - Do honeybees (Apis mellifera) differentiate between different pollen types? JF - PLoS ONE N2 - Bees receive nectar and pollen as reward for pollinating plants. Pollen of different plant species varies widely in nutritional composition. In order to select pollen of appropriate nutritional quality, bees would benefit if they could distinguish different pollen types. Whether they rely on visual, olfactory and/or chemotactile cues to distinguish between different pollen types, has however been little studied. In this study, we examined whether and how Apis mellifera workers differentiate between almond and apple pollen. We used differential proboscis extension response conditioning with olfactory and chemotactile stimulation, in light and darkness, and in summer and winter bees. We found that honeybees were only able to differentiate between different pollen types, when they could use both chemotactile and olfactory cues. Visual cues further improved learning performance. Summer bees learned faster than winter bees. Our results thus highlight the importance of multisensory information for pollen discrimination. KW - pollen KW - bees KW - honey bees KW - conditioned response KW - behavioral conditioning KW - foraging KW - nutrients KW - sensory cues Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177537 VL - 13 IS - 11 ER - TY - JOUR A1 - Beck, Sebastian A1 - Yu-Strzelczyk, Jing A1 - Pauls, Dennis A1 - Constantin, Oana M. A1 - Gee, Christine E. A1 - Ehmann, Nadine A1 - Kittel, Robert J. A1 - Nagel, Georg A1 - Gao, Shiqiang T1 - Synthetic light-activated ion channels for optogenetic activation and inhibition JF - Frontiers in Neuroscience N2 - Optogenetic manipulation of cells or living organisms became widely used in neuroscience following the introduction of the light-gated ion channel channelrhodopsin-2 (ChR2). ChR2 is a non-selective cation channel, ideally suited to depolarize and evoke action potentials in neurons. However, its calcium (Ca2\(^{2+}\)) permeability and single channel conductance are low and for some applications longer-lasting increases in intracellular Ca\(^{2+}\) might be desirable. Moreover, there is need for an efficient light-gated potassium (K\(^{+}\)) channel that can rapidly inhibit spiking in targeted neurons. Considering the importance of Ca\(^{2+}\) and K\(^{+}\) in cell physiology, light-activated Ca\(^{2+}\)-permeant and K\(^{+}\)-specific channels would be welcome additions to the optogenetic toolbox. Here we describe the engineering of novel light-gated Ca\(^{2+}\)-permeant and K\(^{+}\)-specific channels by fusing a bacterial photoactivated adenylyl cyclase to cyclic nucleotide-gated channels with high permeability for Ca\(^{2+}\) or for K\(^{+}\), respectively. Optimized fusion constructs showed strong light-gated conductance in Xenopus laevis oocytes and in rat hippocampal neurons. These constructs could also be used to control the motility of Drosophila melanogaster larvae, when expressed in motoneurons. Illumination led to body contraction when motoneurons expressed the light-sensitive Ca\(^{2+}\)-permeant channel, and to body extension when expressing the light-sensitive K\(^{+}\) channel, both effectively and reversibly paralyzing the larvae. Further optimization of these constructs will be required for application in adult flies since both constructs led to eclosion failure when expressed in motoneurons. KW - optogenetics KW - calcium KW - potassium KW - bPAC KW - CNG channel KW - cAMP KW - Drosophila melanogaster motoneuron KW - rat hippocampal neurons Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177520 VL - 12 IS - 643 ER - TY - JOUR A1 - Pauls, Dennis A1 - Blechschmidt, Christine A1 - Frantzmann, Felix A1 - el Jundi, Basil A1 - Selcho, Mareike T1 - A comprehensive anatomical map of the peripheral octopaminergic/tyraminergic system of Drosophila melanogaster JF - Scientific Reports N2 - The modulation of an animal’s behavior through external sensory stimuli, previous experience and its internal state is crucial to survive in a constantly changing environment. In most insects, octopamine (OA) and its precursor tyramine (TA) modulate a variety of physiological processes and behaviors by shifting the organism from a relaxed or dormant condition to a responsive, excited and alerted state. Even though OA/TA neurons of the central brain are described on single cell level in Drosophila melanogaster, the periphery was largely omitted from anatomical studies. Given that OA/TA is involved in behaviors like feeding, flying and locomotion, which highly depend on a variety of peripheral organs, it is necessary to study the peripheral connections of these neurons to get a complete picture of the OA/TA circuitry. We here describe the anatomy of this aminergic system in relation to peripheral tissues of the entire fly. OA/TA neurons arborize onto skeletal muscles all over the body and innervate reproductive organs, the heart, the corpora allata, and sensory organs in the antennae, legs, wings and halteres underlining their relevance in modulating complex behaviors. KW - neural circuits KW - peripheral nervous system KW - Drosophila melanogaster Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177412 VL - 8 IS - 15314 ER - TY - JOUR A1 - Jarick, Marcel A1 - Bertsche, Ute A1 - Stahl, Mark A1 - Schultz, Daniel A1 - Methling, Karen A1 - Lalk, Michael A1 - Stigloher, Christian A1 - Steger, Mirco A1 - Schlosser, Andreas A1 - Ohlsen, Knut T1 - The serine/threonine kinase Stk and the phosphatase Stp regulate cell wall synthesis in Staphylococcus aureus JF - Scientific Reports N2 - The cell wall synthesis pathway producing peptidoglycan is a highly coordinated and tightly regulated process. Although the major components of bacterial cell walls have been known for decades, the complex regulatory network controlling peptidoglycan synthesis and many details of the cell division machinery are not well understood. The eukaryotic-like serine/threonine kinase Stk and the cognate phosphatase Stp play an important role in cell wall biosynthesis and drug resistance in S. aureus. We show that stp deletion has a pronounced impact on cell wall synthesis. Deletion of stp leads to a thicker cell wall and decreases susceptibility to lysostaphin. Stationary phase Δstp cells accumulate peptidoglycan precursors and incorporate higher amounts of incomplete muropeptides with non-glycine, monoglycine and monoalanine interpeptide bridges into the cell wall. In line with this cell wall phenotype, we demonstrate that the lipid II:glycine glycyltransferase FemX can be phosphorylated by the Ser/Thr kinase Stk in vitro. Mass spectrometric analyses identify Thr32, Thr36 and Ser415 as phosphoacceptors. The cognate phosphatase Stp dephosphorylates these phosphorylation sites. Moreover, Stk interacts with FemA and FemB, but is unable to phosphorylate them. Our data indicate that Stk and Stp modulate cell wall synthesis and cell division at several levels. KW - bacterial transcription KW - pathogens KW - cell wall synthesis Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177333 VL - 8 IS - 13693 ER - TY - JOUR A1 - Grimm, Johannes A1 - Hufnagel, Anita A1 - Wobser, Marion A1 - Borst, Andreas A1 - Haferkamp, Sebastian A1 - Houben, Roland A1 - Meierjohann, Svenja T1 - BRAF inhibition causes resilience of melanoma cell lines by inducing the secretion of FGF1 JF - Oncogenesis N2 - Approximately half of all melanoma patients harbour activating mutations in the serine/threonine kinase BRAF. This is the basis for one of the main treatment strategies for this tumor type, the targeted therapy with BRAF and MEK inhibitors. While the initial responsiveness to these drugs is high, resistance develops after several months, frequently at sites of the previously responding tumor. This indicates that tumor response is incomplete and that a certain tumor fraction survives even in drug-sensitive patients, e.g., in a therapy-induced senescence-like state. Here, we show in several melanoma cell lines that BRAF inhibition induces a secretome with stimulating effect on fibroblasts and naive melanoma cells. Several senescence-associated factors were found to be transcribed and secreted in response to BRAF or MEK inhibition, among them members of the fibroblast growth factor family. We identified the growth factor FGF1 as mediator of resilience towards BRAF inhibition, which limits the pro-apoptotic effects of the drug and activates fibroblasts to secrete HGF. FGF1 regulation was mediated by the PI3K pathway and by FRA1, a direct target gene of the MAPK pathway. When FGFR inhibitors were applied in parallel to BRAF inhibitors, resilience was broken, thus providing a rationale for combined therapeutical application. KW - melanoma KW - senescence KW - BRAF KW - tumor Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177261 VL - 7 IS - 71 ER - TY - JOUR A1 - Kaluza, Benjamin F. A1 - Wallace, Helen M. A1 - Heard, Tim A. A1 - Minden, Vanessa A1 - Klein, Alexandra A1 - Leonhardt, Sara D. T1 - Social bees are fitter in more biodiverse environments JF - Scientific Reports N2 - Bee population declines are often linked to human impacts, especially habitat and biodiversity loss, but empirical evidence is lacking. To clarify the link between biodiversity loss and bee decline, we examined how floral diversity affects (reproductive) fitness and population growth of a social stingless bee. For the first time, we related available resource diversity and abundance to resource (quality and quantity) intake and colony reproduction, over more than two years. Our results reveal plant diversity as key driver of bee fitness. Social bee colonies were fitter and their populations grew faster in more florally diverse environments due to a continuous supply of food resources. Colonies responded to high plant diversity with increased resource intake and colony food stores. Our findings thus point to biodiversity loss as main reason for the observed bee decline. KW - biodiversity KW - ecosystem services KW - social bees KW - fitness Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177231 VL - 8 IS - 12353 ER - TY - JOUR A1 - Zoltner, Martin A1 - Krienitz, Nina A1 - Field, Mark C. A1 - Kramer, Susanne T1 - Comparative proteomics of the two T. brucei PABPs suggests that PABP2 controls bulk mRNA JF - PLoS Neglected Tropical Diseases N2 - Poly(A)-binding proteins (PABPs) regulate mRNA fate by controlling stability and translation through interactions with both the poly(A) tail and eIF4F complex. Many organisms have several paralogs of PABPs and eIF4F complex components and it is likely that different eIF4F/PABP complex combinations regulate distinct sets of mRNAs. Trypanosomes have five eIF4G paralogs, six of eIF4E and two PABPs, PABP1 and PABP2. Under starvation, polysomes dissociate and the majority of mRNAs, most translation initiation factors and PABP2 reversibly localise to starvation stress granules. To understand this more broadly we identified a protein interaction cohort for both T. brucei PABPs by cryo-mill/affinity purification-mass spectrometry. PABP1 very specifically interacts with the previously identified interactors eIF4E4 and eIF4G3 and few others. In contrast PABP2 is promiscuous, with a larger set of interactors including most translation initiation factors and most prominently eIF4G1, with its two partners TbG1-IP and TbG1-IP2. Only RBP23 was specific to PABP1, whilst 14 RNA-binding proteins were exclusively immunoprecipitated with PABP2. Significantly, PABP1 and associated proteins are largely excluded from starvation stress granules, but PABP2 and most interactors translocate to granules on starvation. We suggest that PABP1 regulates a small subpopulation of mainly small-sized mRNAs, as it interacts with a small and distinct set of proteins unable to enter the dominant pathway into starvation stress granules and localises preferentially to a subfraction of small polysomes. By contrast PABP2 likely regulates bulk mRNA translation, as it interacts with a wide range of proteins, enters stress granules and distributes over the full range of polysomes. KW - Trypanosoma KW - mRNA KW - T. brucei KW - PABPs Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177126 VL - 12 IS - 7 ER - TY - JOUR A1 - Redlich, Sarah A1 - Martin, Emily A. A1 - Wende, Beate A1 - Steffan-Dewenter, Ingolf T1 - Landscape heterogeneity rather than crop diversity mediates bird diversity in agricultural landscapes JF - PLoS ONE N2 - Crop diversification has been proposed as farm management tool that could mitigate the externalities of conventional farming while reducing productivity-biodiversity trade-offs. Yet evidence for the acclaimed biodiversity benefits of landscape-level crop diversity is ambiguous. Effects may strongly depend on spatial scale and the level of landscape heterogeneity (e.g. overall habitat diversity). At the same time, contrasting within-taxon responses obscure benefits to specific functional groups (i.e. species with shared characteristics or requirements) if studied at the community level. The objectives of this study were to 1) disentangle the relative effects of crop diversity and landscape heterogeneity on avian species richness across five spatial scales ranging from 250 to 3000 m radii around focal winter wheat fields; and 2) assess whether functional groups (feeding guild, conservation status, habitat preference, nesting behaviour) determine the strength and direction of responses to crop diversity and landscape heterogeneity. In central Germany, 14 landscapes were selected along independent gradients of crop diversity (annual arable crops) and landscape heterogeneity. Bird species richness in each landscape was estimated using four point counts throughout the breeding season. We found no effects of landscape-level crop diversity on bird richness and functional groups. Instead, landscape heterogeneity was strongly associated with increased total bird richness across all spatial scales. In particular, insect-feeding and non-farmland birds were favoured in heterogeneous landscapes, as were species not classified as endangered or vulnerable on the regional Red List. Crop-nesting farmland birds, however, were less species-rich in these landscapes. Accordingly, crop diversification may be less suitable for conserving avian diversity and associated ecosystem services (e.g. biological pest control), although confounding interactions with management intensity need yet to be confirmed. In contrast, enhancement of landscape heterogeneity by increasing perennial habitat diversity, reducing field sizes and the amount of cropland has the potential to benefit overall bird richness. Specialist farmland birds, however, may require more targeted management approaches. KW - bird diversity KW - crop diversity KW - landscape heterogeneity Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177110 VL - 13 IS - 8 ER - TY - JOUR A1 - Schlichting, Matthias A1 - Rieger, Dirk A1 - Cusumano, Paola A1 - Grebler, Rudi A1 - Costa, Rodolfo A1 - Mazzotta, Gabriella M. A1 - Helfrich-Förster, Charlotte T1 - Cryptochrome interacts with actin and enhances eye-mediated light sensitivity of the circadian clock in Drosophila melanogaster JF - Frontiers in Molecular Neuroscience N2 - Cryptochromes (CRYs) are a class of flavoproteins that sense blue light. In animals, CRYs are expressed in the eyes and in the clock neurons that control sleep/wake cycles and are implied in the generation and/or entrainment of circadian rhythmicity. Moreover, CRYs are sensing magnetic fields in insects as well as in humans. Here, we show that in the fruit fly Drosophila melanogaster CRY plays a light-independent role as “assembling” protein in the rhabdomeres of the compound eyes. CRY interacts with actin and appears to increase light sensitivity of the eyes by keeping the “signalplex” of the phototransduction cascade close to the membrane. By this way, CRY also enhances light-responses of the circadian clock. KW - Drosophila melanogaster KW - cryptochrome KW - F-actin KW - phototransduction KW - activity rhythms Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177086 VL - 11 IS - 238 ER - TY - JOUR A1 - Boetzl, Fabian A. A1 - Ries, Elena A1 - Schneider, Gudrun A1 - Krauss, Jochen T1 - It’s a matter of design - how pitfall trap design affects trap samples and possible predictions JF - PeerJ N2 - Background: Pitfall traps are commonly used to assess ground dwelling arthropod communities. The effects of different pitfall trap designs on the trapping outcome are poorly investigated however they might affect conclusions drawn from pitfall trap data greatly. Methods: We tested four pitfall trap types which have been used in previous studies for their effectiveness: a simple type, a faster exchangeable type with an extended plastic rim plate and two types with guidance barriers (V- and X-shaped). About 20 traps were active for 10 weeks and emptied biweekly resulting in 100 trap samples. Results: Pitfall traps with guidance barriers were up to five times more effective than simple pitfall traps and trap samples resulted in more similar assemblage approximations. Pitfall traps with extended plastic rim plates did not only perform poorly but also resulted in distinct carabid assemblages with less individuals of small species and a larger variation. Discussion: Due to the obvious trait filtering and resulting altered assemblages, we suggest not to use pitfall traps with extended plastic rim plates. In comprehensive biodiversity inventories, a smaller number of pitfall traps with guidance barriers and a larger number of spatial replicates is of advantage, while due to comparability reasons, the use of simple pitfall traps will be recommended in most other cases. KW - biodiversity estimation KW - spiders KW - carabid beetles KW - ground dwelling predators KW - staphylinid beetles KW - sampling method KW - inventory KW - species richness Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176870 VL - 6 IS - e5078 ER - TY - JOUR A1 - Kaltdorf, Kristin Verena A1 - Theiss, Maria A1 - Markert, Sebastian Matthias A1 - Zhen, Mei A1 - Dandekar, Thomas A1 - Stigloher, Christian A1 - Kollmannsberger, Philipp T1 - Automated classification of synaptic vesicles in electron tomograms of C. elegans using machine learning JF - PLoS ONE N2 - Synaptic vesicles (SVs) are a key component of neuronal signaling and fulfil different roles depending on their composition. In electron micrograms of neurites, two types of vesicles can be distinguished by morphological criteria, the classical “clear core” vesicles (CCV) and the typically larger “dense core” vesicles (DCV), with differences in electron density due to their diverse cargos. Compared to CCVs, the precise function of DCVs is less defined. DCVs are known to store neuropeptides, which function as neuronal messengers and modulators [1]. In C. elegans, they play a role in locomotion, dauer formation, egg-laying, and mechano- and chemosensation [2]. Another type of DCVs, also referred to as granulated vesicles, are known to transport Bassoon, Piccolo and further constituents of the presynaptic density in the center of the active zone (AZ), and therefore are important for synaptogenesis [3]. To better understand the role of different types of SVs, we present here a new automated approach to classify vesicles. We combine machine learning with an extension of our previously developed vesicle segmentation workflow, the ImageJ macro 3D ART VeSElecT. With that we reliably distinguish CCVs and DCVs in electron tomograms of C. elegans NMJs using image-based features. Analysis of the underlying ground truth data shows an increased fraction of DCVs as well as a higher mean distance between DCVs and AZs in dauer larvae compared to young adult hermaphrodites. Our machine learning based tools are adaptable and can be applied to study properties of different synaptic vesicle pools in electron tomograms of diverse model organisms. KW - synaptic vesicles KW - Caenorhabditis elegans KW - machine learning Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176831 VL - 13 IS - 10 ER - TY - JOUR A1 - König, Julia A1 - Guerreiro, Marco Alexandre A1 - Peršoh, Derek A1 - Begerow, Dominik A1 - Krauss, Jochen T1 - Knowing your neighbourhood - the effects of Epichloë endophytes on foliar fungal assemblages in perennial ryegrass in dependence of season and land-use intensity JF - PeerJ N2 - Epichloë endophytes associated with cool-season grass species can protect their hosts from herbivory and can suppress mycorrhizal colonization of the hosts’ roots. However, little is known about whether or not Epichloë endophyte infection can also change the foliar fungal assemblages of the host. We tested 52 grassland study sites along a land-use intensity gradient in three study regions over two seasons (spring vs. summer) to determine whether Epichloë infection of the host grass Lolium perenne changes the fungal community structure in leaves. Foliar fungal communities were assessed by Next Generation Sequencing of the ITS rRNA gene region. Fungal community structure was strongly affected by study region and season in our study, while land-use intensity and infection with Epichloë endophytes had no significant effects. We conclude that effects on non-systemic endophytes resulting from land use practices and Epichloë infection reported in other studies were masked by local and seasonal variability in this study’s grassland sites. KW - endophytic fungi KW - symbiosis KW - Lolium perenne KW - land use KW - fungus-plant interaction KW - foliar fungal community KW - Epichloë Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176814 VL - 6 IS - e4660 ER - TY - JOUR A1 - Biscotti, Maria Assunta A1 - Adolfi, Mateus Contar A1 - Barucca, Marco A1 - Forconi, Mariko A1 - Pallavicini, Alberto A1 - Gerdol, Marco A1 - Canapa, Adriana A1 - Schartl, Manfred T1 - A comparative view on sex differentiation and gametogenesis genes in lungfish and coelacanths JF - Genome Biology and Evolution N2 - Gonadal sex differentiation and reproduction are the keys to the perpetuation of favorable gene combinations and positively selected traits. In vertebrates, several gonad development features that differentiate tetrapods and fishes are likely to be, at least in part, related to the water-to-land transition. The collection of information from basal sarcopterygians, coelacanths, and lungfishes, is crucial to improve our understanding of the molecular evolution of pathways involved in reproductive functions, since these organisms are generally regarded as “living fossils” and as the direct ancestors of tetrapods. Here, we report for the first time the characterization of >50 genes related to sex differentiation and gametogenesis in Latimeria menadoensis and Protopterus annectens. Although the expression profiles of most genes is consistent with the intermediate position of basal sarcopterygians between actinopterygian fish and tetrapods, their phylogenetic placement and presence/absence patterns often reveal a closer affinity to the tetrapod orthologs. On the other hand, particular genes, for example, the male gonad factor gsdf (Gonadal Soma-Derived Factor), provide examples of ancestral traits shared with actinopterygians, which disappeared in the tetrapod lineage. KW - sex differentiation KW - Latimeria menadoensis KW - Protopterus annectens KW - evolution KW - testis KW - gametogenesis KW - ovary Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176774 VL - 10 IS - 6 ER - TY - JOUR A1 - Sarukhanyan, Edita A1 - Shityakov, Sergey A1 - Dandekar, Thomas T1 - In silico designed Axl receptor blocking drug candidates against Zika virus infection JF - ACS Omega N2 - After a large outbreak in Brazil, novel drugs against Zika virus became extremely necessary. Evaluation of virus-based pharmacological strategies concerning essential host factors brought us to the idea that targeting the Axl receptor by blocking its dimerization function could be critical for virus entry. Starting from experimentally validated compounds, such as RU-301, RU-302, warfarin, and R428, we identified a novel compound 2′ (R428 derivative) to be the most potent for this task amongst a number of alternative compounds and leads. The improved affinity of compound 2′ was confirmed by molecular docking as well as molecular dynamics simulation techniques using implicit solvation models. The current study summarizes a new possibility for inhibition of the Axl function as a potential target for future antiviral therapies. KW - free energy KW - molecular docking KW - molecular dynamics KW - simulation KW - pharmacology KW - proteins KW - structure-activity relationship KW - viruses KW - Zika virus Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176739 VL - 3 IS - 5 ER - TY - JOUR A1 - Kottler, Verena A. A1 - Schartl, Manfred T1 - The colorful sex chromosomes of teleost fish JF - Genes N2 - Teleost fish provide some of the most intriguing examples of sexually dimorphic coloration, which is often advantageous for only one of the sexes. Mapping studies demonstrated that the genetic loci underlying such color patterns are frequently in tight linkage to the sex-determining locus of a species, ensuring sex-specific expression of the corresponding trait. Several genes affecting color synthesis and pigment cell development have been previously described, but the color loci on the sex chromosomes have mostly remained elusive as yet. Here, we summarize the current knowledge about the genetics of such color loci in teleosts, mainly from studies on poeciliids and cichlids. Further studies on these color loci will certainly provide important insights into the evolution of sex chromosomes. KW - teleost fish KW - sex chromosomes KW - coloration KW - pigment pattern KW - sexual conflict KW - sexually antagonistic genes Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176587 VL - 9 IS - 5 ER - TY - JOUR A1 - Börtlein, Charlene A1 - Draeger, Annette A1 - Schoenauer, Roman A1 - Kuhlemann, Alexander A1 - Sauer, Markus A1 - Schneider-Schaulies, Sybille A1 - Avota, Elita T1 - The neutral sphingomyelinase 2 is required to polarize and sustain T Cell receptor signaling JF - Frontiers in Immunology N2 - By promoting ceramide release at the cytosolic membrane leaflet, the neutral sphingomyelinase 2 (NSM) is capable of organizing receptor and signalosome segregation. Its role in T cell receptor (TCR) signaling remained so far unknown. We now show that TCR-driven NSM activation is dispensable for TCR clustering and initial phosphorylation, but of crucial importance for further signal amplification. In particular, at low doses of TCR stimulatory antibodies, NSM is required for Ca\(^{2+}\) mobilization and T cell proliferation. NSM-deficient T cells lack sustained CD3ζ and ZAP-70 phosphorylation and are unable to polarize and stabilize their microtubular system. We identified PKCζ as the key NSM downstream effector in this second wave of TCR signaling supporting dynamics of microtubule-organizing center (MTOC). Ceramide supplementation rescued PKCζ membrane recruitment and MTOC translocation in NSM-deficient cells. These findings identify the NSM as essential in TCR signaling when dynamic cytoskeletal reorganization promotes continued lateral and vertical supply of TCR signaling components: CD3ζ, Zap70, and PKCζ, and functional immune synapses are organized and stabilized via MTOC polarization. KW - neutral sphingomyelinase 2 KW - T cells KW - ceramides KW - PKCζ, KW - the microtubule-organizing center Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176572 VL - 9 IS - 815 ER - TY - JOUR A1 - Kohl, Patrick Laurenz A1 - Rutschmann, Benjamin T1 - The neglected bee trees: European beech forests as a home for feral honey bee colonies JF - PeerJ N2 - It is a common belief that feral honey bee colonies (Apis mellifera L.) were eradicated in Europe through the loss of habitats, domestication by man and spread of pathogens and parasites. Interestingly, no scientific data are available, neither about the past nor the present status of naturally nesting honeybee colonies. We expected near-natural beech (Fagus sylvatica L.) forests to provide enough suitable nest sites to be a home for feral honey bee colonies in Europe. Here, we made a first assessment of their occurrence and density in two German woodland areas based on two methods, the tracing of nest sites based on forager flight routes (beelining technique), and the direct inspection of potential cavity trees. Further, we established experimental swarms at forest edges and decoded dances for nest sites performed by scout bees in order to study how far swarms from beekeeper-managed hives would potentially move into a forest. We found that feral honey bee colonies regularly inhabit tree cavities in near-natural beech forests at densities of at least 0.11-0.14 colonies/km\(^{2}\). Colonies were not confined to the forest edges; they were also living deep inside the forests. We estimated a median distance of 2,600 m from the bee trees to the next apiaries, while scout bees in experimental swarms communicated nest sites in close distances (median: 470 m). We extrapolate that there are several thousand feral honey bee colonies in German woodlands. These have to be taken in account when assessing the role of forest areas in providing pollination services to the surrounding land, and their occurrence has implications for the species' perception among researchers, beekeepers and conservationists. This study provides a starting point for investigating the life-histories and the ecological interactions of honey bees in temperate European forest environments. KW - Apis mellifera KW - beech forests KW - black woodpecker KW - dispersal KW - Fagus sylvatica KW - feral honey bees KW - hollow tree KW - swarming KW - tree cavity KW - wild honey bees Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176512 VL - 6 IS - e4602 ER - TY - JOUR A1 - Tauscher, Sabine A1 - Nakagawa, Hitoshi A1 - Völker, Katharina A1 - Werner, Franziska A1 - Krebes, Lisa A1 - Potapenko, Tamara A1 - Doose, Sören A1 - Birkenfeld, Andreas L. A1 - Baba, Hideo A. A1 - Kuhn, Michaela T1 - β Cell-specific deletion of guanylyl cyclase A, the receptor for atrial natriuretic peptide, accelerates obesity-induced glucose intolerance in mice JF - Cardiovascular Diabetology N2 - Background: The cardiac hormones atrial (ANP) and B-type natriuretic peptides (BNP) moderate arterial blood pressure and improve energy metabolism as well as insulin sensitivity via their shared cGMP-producing guanylyl cyclase-A (GC-A) receptor. Obesity is associated with impaired NP/GC-A/cGMP signaling, which possibly contributes to the development of type 2 diabetes and its cardiometabolic complications. In vitro, synthetic ANP, via GC-A, stimulates glucose-dependent insulin release from cultured pancreatic islets and β-cell proliferation. However, the relevance for systemic glucose homeostasis in vivo is not known. To dissect whether the endogenous cardiac hormones modulate the secretory function and/or proliferation of β-cells under (patho)physiological conditions in vivo, here we generated a novel genetic mouse model with selective disruption of the GC-A receptor in β-cells. Methods: Mice with a floxed GC-A gene were bred to Rip-CreTG mice, thereby deleting GC-A selectively in β-cells (β GC-A KO). Weight gain, glucose tolerance, insulin sensitivity, and glucose-stimulated insulin secretion were monitored in normal diet (ND)- and high-fat diet (HFD)-fed mice. β-cell size and number were measured by immunofluorescence-based islet morphometry. Results: In vitro, the insulinotropic and proliferative actions of ANP were abolished in islets isolated from β GC-A KO mice. Concordantly, in vivo, infusion of BNP mildly enhanced baseline plasma insulin levels and glucose-induced insulin secretion in control mice. This effect of exogenous BNP was abolished in β GC-A KO mice, corroborating the efficient inactivation of the GC-A receptor in β-cells. Despite this under physiological, ND conditions, fasted and fed insulin levels, glucose-induced insulin secretion, glucose tolerance and β-cell morphology were similar in β GC-A KO mice and control littermates. However, HFD-fed β GC-A KO animals had accelerated glucose intolerance and diminished adaptative β-cell proliferation. Conclusions: Our studies of β GC-A KO mice demonstrate that the cardiac hormones ANP and BNP do not modulate β-cell's growth and secretory functions under physiological, normal dietary conditions. However, endogenous NP/GC-A signaling improves the initial adaptative response of β-cells to HFD-induced obesity. Impaired β-cell NP/GC-A signaling in obese individuals might contribute to the development of type 2 diabetes. KW - cylic GMP KW - guanylyl cyclase-A KW - insulin KW - natriuretic peptides KW - obesity KW - β-cells Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176322 VL - 17 IS - 103 ER - TY - JOUR A1 - Pelz, Jörg O. W. A1 - Wagner, Johanna A1 - Lichthardt, Sven A1 - Baur, Johannes A1 - Kastner, Caroline A1 - Matthes, Niels A1 - Germer, Christoph-Thomas A1 - Wiegering, Armin T1 - Laparoscopic right-sided colon resection for colon cancer - has the control group so far been chosen correctly? JF - World Journal of Surgical Oncology N2 - Background: The treatment strategies for colorectal cancer located in the right side of the colon have changed dramatically during the last decade. Due to the introduction of complete mesocolic excision (CME) with central ligation of the vessels and systematic lymph node dissection, the long-term survival of affected patients has increased significantly. It has also been proposed that right-sided colon resection can be performed laparoscopically with the same extent of resection and equal long-term results. Methods: A retrospective evaluation of a prospectively expanded database on right-sided colorectal cancer or adenoma treated at the University Hospital of Wuerzburg between 2009 and 2016 was performed. All patients underwent CME. This data was analyzed alone and in comparison to the published data describing laparoscopic right-sided colon resection for colon cancer. Results: The database contains 279 patients, who underwent right-sided colon resection due to colorectal cancer or colorectal adenoma (255 open; 24 laparoscopic). Operation data (time, length of stay, time on ICU) was equal or superior to laparoscopy, which is comparable to the published results. Surprisingly, the surrogate parameter for correct CME (the number of removed lymph nodes) was significantly higher in the open group. In a subgroup analysis only including patients who were feasible for laparoscopic resection and had been operated with an open procedure by an experienced surgeon, operation time was significantly shorter and the number of removed lymph nodes is significantly higher in the open group. Conclusion: So far, several studies demonstrate that laparoscopic right-sided colon resection is comparable to open resection. Our data suggests that a consequent CME during an open operation leads to significantly more removed lymph nodes than in laparoscopically resected patients and in several so far published data of open control groups from Europe. Further prospective randomized trials comparing the long-term outcome are urgently needed before laparoscopy for right-sided colon resection can be recommended ubiquitously. KW - colon cancer KW - laparoscopic right colectomy KW - lymph nodes Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176186 VL - 16 IS - 117 ER - TY - INPR A1 - Löffler, Mona C. A1 - Mayer, Alexander E. A1 - Trujillo Viera, Jonathan A1 - Loza Valdes, Angel A1 - El-Merahib, Rabih A1 - Ade, Carsten P. A1 - Karwen, Till A1 - Schmitz, Werner A1 - Slotta, Anja A1 - Erk, Manuela A1 - Janaki-Raman, Sudha A1 - Matesanz, Nuria A1 - Torres, Jorge L. A1 - Marcos, Miguel A1 - Sabio, Guadalupe A1 - Eilers, Martin A1 - Schulze, Almut A1 - Sumara, Grzegorz T1 - Protein kinase D1 deletion in adipocytes enhances energy dissipation and protects against adiposity T2 - The EMBO Journal N2 - Nutrient overload in combination with decreased energy dissipation promotes obesity and diabetes. Obesity results in a hormonal imbalance, which among others, activates G-protein coupled receptors utilizing diacylglycerol (DAG) as secondary messenger. Protein kinase D1 (PKD1) is a DAG effector which integrates multiple nutritional and hormonal inputs, but its physiological role in adipocytes is unknown. Here, we show that PKD1 promotes lipogenesis and suppresses mitochondrial fragmentation, biogenesis, respiration, and energy dissipation in an AMP-activated protein kinase (AMPK)-dependent manner. Moreover, mice lacking PKD1 in adipocytes are resistant to diet-induced obesity due to elevated energy expenditure. Beiging of adipocytes promotes energy expenditure and counteracts obesity. Consistently, deletion of PKD1 promotes expression of the β3-adrenergic receptor (ADRB3) in a CCAAT/enhancerbinding protein (C/EBP)-α and δ-dependent manner, which leads to the elevated expression of beige markers in adipocytes and subcutaneous adipose tissue. Finally, deletion of PKD1 in adipocytes improves insulin sensitivity and ameliorates liver steatosis. Thus, loss of PKD1 in adipocytes increases energy dissipation by several complementary mechanisms and might represent an attractive strategy to treat obesity and its related complications. KW - AMP-activated protein kinase (AMPK) KW - Beige adipocytes KW - β3 adrenergic receptor (ADRB3) KW - C/EBP KW - Protein kinase D1 (PKD1) Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176093 ER - TY - JOUR A1 - Krüger, Timothy A1 - Engstler, Markus T1 - The fantastic voyage of the trypanosome: a protean micromachine perfected during 500 million years of engineering JF - Micromachines N2 - The human body is constantly attacked by pathogens. Various lines of defence have evolved, among which the immune system is principal. In contrast to most pathogens, the African trypanosomes thrive freely in the blood circulation, where they escape immune destruction by antigenic variation and incessant motility. These unicellular parasites are flagellate microswimmers that also withstand the harsh mechanical forces prevailing in the bloodstream. They undergo complex developmental cycles in the bloodstream and organs of the mammalian host, as well as the disease-transmitting tsetse fly. Each life cycle stage has been shaped by evolution for manoeuvring in distinct microenvironments. Here, we introduce trypanosomes as blueprints for nature-inspired design of trypanobots, micromachines that, in the future, could explore the human body without affecting its physiology. We review cell biological and biophysical aspects of trypanosome motion. While this could provide a basis for the engineering of microbots, their actuation and control still appear more like fiction than science. Here, we discuss potentials and challenges of trypanosome-inspired microswimmer robots. KW - trypanosoma KW - microswimmer KW - parasite KW - flagellate KW - microenvironment KW - cellular waveform KW - tsetse KW - microbot KW - trypanobot Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-175944 VL - 9 IS - 2 ER - TY - JOUR A1 - Kropf, Jan A1 - Rössler, Wolfgang T1 - In-situ recording of ionic currents in projection neurons and Kenyon cells in the olfactory pathway of the honeybee JF - PLoS ONE N2 - The honeybee olfactory pathway comprises an intriguing pattern of convergence and divergence: ~60.000 olfactory sensory neurons (OSN) convey olfactory information on ~900 projection neurons (PN) in the antennal lobe (AL). To transmit this information reliably, PNs employ relatively high spiking frequencies with complex patterns. PNs project via a dual olfactory pathway to the mushroom bodies (MB). This pathway comprises the medial (m-ALT) and the lateral antennal lobe tract (l-ALT). PNs from both tracts transmit information from a wide range of similar odors, but with distinct differences in coding properties. In the MBs, PNs form synapses with many Kenyon cells (KC) that encode odors in a spatially and temporally sparse way. The transformation from complex information coding to sparse coding is a well-known phenomenon in insect olfactory coding. Intrinsic neuronal properties as well as GABAergic inhibition are thought to contribute to this change in odor representation. In the present study, we identified intrinsic neuronal properties promoting coding differences between PNs and KCs using in-situ patch-clamp recordings in the intact brain. We found very prominent K+ currents in KCs clearly differing from the PN currents. This suggests that odor coding differences between PNs and KCs may be caused by differences in their specific ion channel properties. Comparison of ionic currents of m- and l-ALT PNs did not reveal any differences at a qualitative level. KW - action potentials KW - olfaction KW - honeybee Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-175869 VL - 13 IS - 1 ER - TY - JOUR A1 - Hesselbach, Hannah A1 - Scheiner, Ricarda T1 - Effects of the novel pesticide flupyradifurone (Sivanto) on honeybee taste and cognition JF - Scientific Reports N2 - Due to intensive agriculture honeybees are threatened by various pesticides. The use of one group of them, the neonicotinoids, was recently restricted by the European Union. These chemicals bind to the nicotinic acetylcholine receptor (nAchR) in the honeybee brain. Recently, Bayer AG released a new pesticide by the name of “Sivanto” against sucking insects. It is assumed to be harmless for honeybees, although its active ingredient, flupyradifurone, binds nAchR similar to the neonicotinoids. We investigated if this pesticide affects the taste for sugar and cognitive performance in honeybee foragers. These bees are directly exposed to the pesticide while foraging for pollen or nectar. Our results demonstrate that flupyradifurone can reduce taste and appetitive learning performance in honeybees foraging for pollen and nectar, although only the highest concentration had significant effects. Most likely, honeybee foragers will not be exposed to these high concentrations. Therefore, the appropriate use of this pesticide is considered safe for honeybees, at least with respect to the behaviors studied here. KW - animal behaviour KW - chemical ecology KW - pesticide KW - honeybee KW - taste KW - cognition KW - flupyradifurone Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-175853 VL - 8 IS - 4954 ER - TY - JOUR A1 - Schartl, Manfred A1 - Schories, Susanne A1 - Watamatsu, Yuko A1 - Nagao, Yusuke A1 - Hashimoto, Hisashi A1 - Bertin, Chloé A1 - Mourot, Brigitte A1 - Schmidt, Cornelia A1 - Wilhelm, Dagmar A1 - Centanin, Lazaro A1 - Guiguen, Yann A1 - Herpin, Amaury T1 - Sox5 is involved in germ-cell regulation and sex determination in medaka following co-option of nested transposable elements JF - BMC Biology N2 - Background: Sex determination relies on a hierarchically structured network of genes, and is one of the most plastic processes in evolution. The evolution of sex-determining genes within a network, by neo- or sub-functionalization, also requires the regulatory landscape to be rewired to accommodate these novel gene functions. We previously showed that in medaka fish, the regulatory landscape of the master male-determining gene dmrt1bY underwent a profound rearrangement, concomitantly with acquiring a dominant position within the sex-determining network. This rewiring was brought about by the exaptation of a transposable element (TE) called Izanagi, which is co-opted to act as a silencer to turn off the dmrt1bY gene after it performed its function in sex determination. Results: We now show that a second TE, Rex1, has been incorporated into Izanagi. The insertion of Rex1 brought in a preformed regulatory element for the transcription factor Sox5, which here functions in establishing the temporal and cell-type-specific expression pattern of dmrt1bY. Mutant analysis demonstrates the importance of Sox5 in the gonadal development of medaka, and possibly in mice, in a dmrt1bY-independent manner. Moreover, Sox5 medaka mutants have complete female-to-male sex reversal. Conclusions: Our work reveals an unexpected complexity in TE-mediated transcriptional rewiring, with the exaptation of a second TE into a network already rewired by a TE. We also show a dual role for Sox5 during sex determination: first, as an evolutionarily conserved regulator of germ-cell number in medaka, and second, by de novo regulation of dmrt1 transcriptional activity during primary sex determination due to exaptation of the Rex1 transposable element. KW - Dmrt1bY KW - Sox5 KW - exaptation KW - master sex-determining gene KW - transcriptional rewiring KW - medaka Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-175827 VL - 16 IS - 16 ER - TY - JOUR A1 - Hofrichter, Michaela A. H. A1 - Mojarad, Majid A1 - Doll, Julia A1 - Grimm, Clemens A1 - Eslahi, Atiye A1 - Hosseini, Neda Sadat A1 - Rajati, Mohsen A1 - Müller, Tobias A1 - Dittrich, Marcus A1 - Maroofian, Reza A1 - Haaf, Thomas A1 - Vona, Barbara T1 - The conserved p.Arg108 residue in S1PR2 (DFNB68) is fundamental for proper hearing: evidence from a consanguineous Iranian family JF - BMC Medical Genetics N2 - Background: Genetic heterogeneity and consanguineous marriages make recessive inherited hearing loss in Iran the second most common genetic disorder. Only two reported pathogenic variants (c.323G>C, p.Arg108Pro and c.419A>G, p.Tyr140Cys) in the S1PR2 gene have previously been linked to autosomal recessive hearing loss (DFNB68) in two Pakistani families. We describe a segregating novel homozygous c.323G>A, p.Arg108Gln pathogenic variant in S1PR2 that was identified in four affected individuals from a consanguineous five generation Iranian family. Methods: Whole exome sequencing and bioinformatics analysis of 116 hearing loss-associated genes was performed in an affected individual from a five generation Iranian family. Segregation analysis and 3D protein modeling of the p.Arg108 exchange was performed. Results: The two Pakistani families previously identified with S1PR2 pathogenic variants presented profound hearing loss that is also observed in the affected Iranian individuals described in the current study. Interestingly, we confirmed mixed hearing loss in one affected individual. 3D protein modeling suggests that the p.Arg108 position plays a key role in ligand receptor interaction, which is disturbed by the p.Arg108Gln change. Conclusion: In summary, we report the third overall mutation in S1PR2 and the first report outside the Pakistani population. Furthermore, we describe a novel variant that causes an amino acid exchange (p.Arg108Gln) in the same amino acid residue as one of the previously reported Pakistani families (p.Arg108Pro). This finding emphasizes the importance of the p.Arg108 amino acid in normal hearing and confirms and consolidates the role of S1PR2 in autosomal recessive hearing loss. KW - 3D modeling KW - autosomal recessive non-synstromic hearing loss KW - DFNB68 KW - mixed hearing loss KW - whole exome sequencing KW - S1PR2 Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-175755 VL - 19 IS - 81 ER - TY - JOUR A1 - Lichtenstein, Leonie A1 - Grübel, Kornelia A1 - Spaethe, Johannes T1 - Opsin expression patterns coincide with photoreceptor development during pupal development in the honey bee, Apis mellifera JF - BMC Developmental Biology N2 - Background: The compound eyes of insects allow them to catch photons and convert the energy into electric signals. All compound eyes consist of numerous ommatidia, each comprising a fixed number of photoreceptors. Different ommatidial types are characterized by a specific set of photoreceptors differing in spectral sensitivity. In honey bees, males and females possess different ommatidial types forming distinct retinal mosaics. However, data are lacking on retinal ontogeny and the mechanisms by which the eyes are patterned. In this study, we investigated the intrinsic temporal and circadian expression patterns of the opsins that give rise to the ultraviolet, blue and green sensitive photoreceptors, as well as the morphological maturation of the retina during pupal development of honey bees. Results: qPCR and histological labeling revealed that temporal opsin mRNA expression differs between sexes and correlates with rhabdom elongation during photoreceptor development. In the first half of the pupal stage, when the rhabdoms of the photoreceptors are still short, worker and (dorsal) drone retinae exhibit similar expression patterns with relatively high levels of UV (UVop) and only marginal levels of blue (BLop) and green (Lop1) opsin mRNA. In the second half of pupation, when photoreceptors and rhabdoms elongate, opsin expression in workers becomes dominated by Lop1 mRNA. In contrast, the dorsal drone eye shows high expression levels of UVop and BLop mRNA, whereas Lop1 mRNA level decreases. Interestingly, opsin expression levels increase up to 22-fold during early adult life. We also found evidence that opsin expression in adult bees is under the control of the endogenous clock. Conclusions: Our data indicate that the formation of the sex-specific retinal composition of photoreceptors takes place during the second half of the pupal development, and that opsin mRNA expression levels continue to increase in young bees, which stands in contrast to Drosophila, where the highest expression levels are found during the late pupal stage and remain constant in adults. From an evolutionary perspective, we hypothesize that the delayed retinal maturation during the early adult phase is linked to the delayed transition from indoor to outdoor activities in bees, when vision becomes important. KW - insect vision KW - photoreceptor KW - spectral sensitivity KW - visual pigments KW - behavioral transition Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-175665 VL - 18 IS - 1 ER - TY - JOUR A1 - Bartmann, Catharina A1 - Janaki Raman, Sudha R. A1 - Flöter, Jessica A1 - Schulze, Almut A1 - Bahlke, Katrin A1 - Willingstorfer, Jana A1 - Strunz, Maria A1 - Wöckel, Achim A1 - Klement, Rainer J. A1 - Kapp, Michaela A1 - Djuzenova, Cholpon S. A1 - Otto, Christoph A1 - Kämmerer, Ulrike T1 - Beta-hydroxybutyrate (3-OHB) can influence the energetic phenotype of breast cancer cells, but does not impact their proliferation and the response to chemotherapy or radiation JF - Cancer & Metabolism N2 - Background: Ketogenic diets (KDs) or short-term fasting are popular trends amongst supportive approaches for cancer patients. Beta-hydroxybutyrate (3-OHB) is the main physiological ketone body, whose concentration can reach plasma levels of 2–6 mM during KDs or fasting. The impact of 3-OHB on the biology of tumor cells described so far is contradictory. Therefore, we investigated the effect of a physiological concentration of 3 mM 3-OHB on metabolism, proliferation, and viability of breast cancer (BC) cells in vitro. Methods: Seven different human BC cell lines (BT20, BT474, HBL100, MCF-7, MDA-MB 231, MDA-MB 468, and T47D) were cultured in medium with 5 mM glucose in the presence of 3 mM 3-OHB at mild hypoxia (5% oxygen) or normoxia (21% oxygen). Metabolic profiling was performed by quantification of the turnover of glucose, lactate, and 3-OHB and by Seahorse metabolic flux analysis. Expression of key enzymes of ketolysis as well as the main monocarboxylic acid transporter MCT2 and the glucose-transporter GLUT1 was analyzed by RT-qPCR and Western blotting. The effect of 3-OHB on short- and long-term cell proliferation as well as chemo- and radiosensitivity were also analyzed. Results: 3-OHB significantly changed the oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) in BT20 cells resulting in a more oxidative energetic phenotype. MCF-7 and MDA-MB 468 cells had increased ECAR only in response to 3-OHB, while the other three cell types remained uninfluenced. All cells expressed MCT2 and GLUT1, thus being able to uptake the metabolites. The consumption of 3-OHB was not strongly linked to mRNA overexpression of key enzymes of ketolysis and did not correlate with lactate production and glucose consumption. Neither 3-OHB nor acetoacetate did interfere with proliferation. Further, 3-OHB incubation did not modify the response of the tested BC cell lines to chemotherapy or radiation. Conclusions: We found that a physiological level of 3-OHB can change the energetic profile of some BC cell lines. However, 3-OHB failed to influence different biologic processes in these cells, e.g., cell proliferation and the response to common breast cancer chemotherapy and radiotherapy. Thus, we have no evidence that 3-OHB generally influences the biology of breast cancer cells in vitro. KW - ketogenic diet KW - β-Hydroxybutyrate KW - ketone bodies KW - breast cancer KW - seahorse KW - metabolic profile KW - chemotherapy KW - ionizing radiation Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-175607 VL - 6 IS - 8 ER - TY - THES A1 - Maierhofer, Anna T1 - Altersassoziierte und strahleninduzierte Veränderungen des genomweiten DNA-Methylierungs-Profils T1 - Age-associated and radiation-induced changes in genome-wide DNA methylation N2 - Der Prozess des Alterns ist ein komplexer multifaktorieller Vorgang, der durch eine sukzessive Verschlechterung der physiologischen Funktionen charakterisiert ist. Ein hohes Alter ist der Hauptrisikofaktor für die meisten Krankheiten, einschließlich Krebs und Herz-Kreislauf-Erkrankungen. Das Verständnis der epigenetischen Mechanismen, die in den Prozess des Alterns involviert sind, könnte zur Entwicklung pharmakologischer Interventionen beitragen, die nicht nur die Lebenserwartung erhöhen, sondern auch den Beginn des altersassoziierten funktionellen Abbaus verzögern könnten. Durch die Langzeit-Kultivierung primärer humaner Fibroblasten wurde ein in vitro Modell für das Altern etabliert, das die Identifizierung altersassoziierter DNA-Methylierungs-Veränderungen ermöglichte. Die in vitro Alterung konnte mit einer globalen Hypomethylierung und einer erhöhten DNA-Methylierung der ribosomalen DNA assoziiert werden. Darüber hinaus konnten DNA-Methylierungs-Veränderungen in Genen und Signalwegen, die für das Altern relevant sind, und ein erhöhtes epigenetisches Alter nachgewiesen werden. Das in vitro Modell für das Altern wurde verwendet, um neben den direkten Effekten ionisierender Strahlung auf die DNA-Methylierung auch deren Langzeit-Effekte zu untersuchen. Die Strahlentherapie ist ein entscheidendes Element der Krebstherapie, hat aber auch negative Auswirkungen und kann unter anderem das Risiko für die Entwicklung eines Zweittumors erhöhen. Bei externer Bestrahlung wird neben dem Tumor auch gesundes Gewebe ionisierender Strahlung ausgesetzt. Daher ist es wichtig zu untersuchen, wie Zellen mit intakten DNA-Reparatur-Mechanismen und funktionierenden Zellzyklus-Checkpoints durch diese beeinflusst werden. In der frühen Phase der DNA-Schadensantwort auf Bestrahlung wurden in normalen Zellen keine wesentlichen DNA-Methylierungs-Veränderungen beobachtet. Mehrere Populations-Verdoppelungen nach Strahlenexposition konnten dagegen eine globale Hypomethylierung, eine erhöhte DNA-Methylierung der ribosomalen DNA und ein erhöhtes epigenetisches Alter detektiert werden. Des Weiteren zeigten Gene und Signalwege, die mit Krebs in Verbindung gebracht wurden, Veränderungen in der DNA-Methylierung. Als Langzeit-Effekte ionisierender Strahlung traten somit die mit der in vitro Alterung assoziierten DNA-Methylierungs-Veränderungen verstärkt auf und ein epigenetisches Muster, das stark an das DNA-Methylierungs-Profil von Tumorzellen erinnert, entstand. Man geht davon aus, dass Veränderungen der DNA-Methylierung eine aktive Rolle in der Entwicklung eines Tumors spielen. Die durch ionisierende Strahlung induzierten DNA-Methylierungs-Veränderungen in normalen Zellen könnten demnach in die Krebsentstehung nach Strahlenexposition involviert sein und zu dem sekundären Krebsrisiko nach Strahlentherapie beitragen. Es ist bekannt, dass Patienten unterschiedlich auf therapeutische Bestrahlung reagieren. Die Ergebnisse dieser Arbeit weisen darauf hin, dass die individuelle Sensitivität gegenüber ionisierender Strahlung auch auf epigenetischer Ebene beobachtet werden kann. In einem zweiten Projekt wurden Gesamtblutproben von Patienten mit Werner-Syndrom, einer segmental progeroiden Erkrankung, und gesunden Kontrollen analysiert, um mit dem vorzeitigen Altern in Verbindung stehende DNA-Methylierungs-Veränderungen zu identifizieren. Werner-Syndrom konnte nicht mit einer globalen Hypomethylierung, jedoch mit einer erhöhten DNA-Methylierung der ribosomalen DNA und einem erhöhten epigenetischen Alter assoziiert werden. Das vorzeitige Altern geht demzufolge mit spezifischen epigenetischen Veränderungen einher, die eine Beschleunigung der mit dem normalen Altern auftretenden DNA-Methylierungs-Veränderungen darstellen. Im Rahmen dieser Arbeit konnte die Bedeutung epigenetischer Mechanismen im Prozess des Alterns hervorgehoben werden und gezeigt werden, dass sowohl exogene Faktoren, wie ionisierende Strahlung, als auch endogene Faktoren, wie das in Werner-Syndrom-Patienten mutiert vorliegende WRN-Gen, altersassoziierte DNA-Methylierungs-Veränderungen beeinflussen können. N2 - Aging is a complex, multifactorial process that is characterized by the successive deterioration of normal physiological functions. Age is the main risk factor for most diseases, including cancer. Understanding the epigenetic mechanisms that are involved in the aging process could contribute to the development of pharmacological interventions not only increasing lifespan but also delaying the onset of age-dependent functional decline. An in vitro model for aging was established by long-term culturing of primary human fibroblasts and used to identify age-associated changes in DNA methylation. In vitro aging could be linked to global hypomethylation, elevated DNA methylation of ribosomal DNA, a higher epigenetic age and alterations in DNA methylation of genes and pathways being relevant for aging. The in vitro model for aging allowed to analyse the long-term effects of ionizing radiation on DNA methylation in addition to their direct effects. Radiotherapy is an important element of cancer treatment but can also have negative effects and increase the risk of second cancers. Although radiotherapy is targeted to the tumour, it also affects the surrounding healthy tissue. Therefore, it is important to analyse the impacts of ionizing radiation on normal cells with intact DNA repair and cell cycle checkpoints. The early phase of DNA damage response to radiation does not seem to include great changes in DNA methylation in normal cells. In contrast, several population doublings after radiation exposure, global hypomethylation and DNA methylation changes of genes and pathways being linked to tumorigenesis were detected. Furthermore, DNA methylation of ribosomal DNA and the epigenetic age were increased. Thus, as long-term effects of ionizing radiation the age-associated changes in DNA methylation were enhanced and an epigenetic pattern strongly resembling the DNA methylation profile of tumour cells was observed. It is assumed that alterations in DNA methylation are not only side effects of carcinogenesis but rather play an active role during this process. Radiation-induced changes in DNA methylation could thus be involved in tumour development and contribute to the secondary cancer risk after radiotherapy. It is well known that patients react differently to therapeutic radiation. The results of this study suggest that individual radiation sensitivity is also reflected on epigenetic level. In a second project whole blood samples from patients with Werner syndrome, a segmental progeroid syndrome, and healthy controls were analysed to identify changes in DNA methylation associated with premature aging. Werner syndrome could not be linked to global hypomethylation, but to an increased epigenetic age and elevated methylation levels of ribosomal DNA. Hence, premature aging seems to be accompanied by specific alterations in DNA methylation representing an acceleration of the DNA methylation changes associated with normal aging. This work outlines the importance of epigenetic mechanisms in the aging process and shows that not only exogenous factors like ionizing radiation but also endogenous factors like Werner syndrome causing mutations in the WRN gene can influence age-associated changes in DNA methylation. KW - Methylierung KW - Ionisierende Strahlung KW - Altern KW - Progeria adultorum KW - Epigenetik KW - Epigenetische Uhr Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-174134 ER - TY - THES A1 - Nürnberger, Fabian T1 - Timing of colony phenology and foraging activity in honey bees T1 - Zeitliche Koordination von Koloniephänologie und Sammelaktivität bei Honigbienen N2 - I. Timing is a crucial feature in organisms that live within a variable and changing environment. Complex mechanisms to measure time are wide-spread and were shown to exist in many taxa. These mechanisms are expected to provide fitness benefits by enabling organisms to anticipate environmental changes and adapt accordingly. However, very few studies have addressed the adaptive value of proper timing. The objective of this PhD-project was to investigate mechanisms and fitness consequences of timing decisions concerning colony phenology and foraging activity in the honey bee (Apis mellifera), a social insect species with a high degree of social organization and one of the most important pollinators of wild plants and crops. In chapter II, a study is presented that aimed to identify the consequences of disrupted synchrony between colony phenology and the local environment by manipulating the timing of brood onset after hibernation. In a follow-up experiment, the importance of environmental factors for the timing of brood onset was investigated to assess the potential of climate change to disrupt synchronization of colony phenology (Chapter III). Chapter IV aimed to prove for the first time that honey bees can use interval time-place learning to improve foraging activity in a variable environment. Chapter V investigates the fitness benefits of information exchange between nest mates via waggle dance communication about a resource environment that is heterogeneous in space and time. II. In the study presented in chapter II, the importance of the timing of brood onset after hibernation as critical point in honey bee colony phenology in temperate zones was investigated. Honey bee colonies were overwintered at two climatically different sites. By translocating colonies from each site to the other in late winter, timing of brood onset was manipulated and consequently colony phenology was desynchronized with the local environment. Delaying colony phenology in respect to the local environment decreased the capability of colonies to exploit the abundant spring bloom. Early brood onset, on the other hand, increased the loads of the brood parasite Varroa destructor later in the season with negative impact on colony worker population size. This indicates a timing related trade-off and illustrates the importance of investigating effects of climate change on complex multi-trophic systems. It can be concluded that timing of brood onset in honey bees is an important fitness relevant step for colony phenology that is highly sensitive to climatic conditions in late winter. Further, phenology shifts and mismatches driven by climate change can have severe fitness consequences. III. In chapter III, I assess the importance of the environmental factors ambient temperature and photoperiod as well as elapsed time on the timing of brood onset. Twenty-four hibernating honey bee colonies were placed into environmental chambers and allocated to different combinations of two temperature regimes and three different light regimes. Brood onset was identified non-invasively by tracking comb temperature within the winter cluster. The experiment revealed that ambient temperature plays a major role in the timing of brood onset, but the response of honey bee colonies to temperature increases is modified by photoperiod. Further, the data indicate the involvement of an internal clock. I conclude that the timing of brood onset is complex but probably highly susceptible to climate change and especially spells of warm weather in winter. IV. In chapter IV, it was examined if honey bees are capable of interval time-place learning and if this ability improves foraging efficiency in a dynamic resource environment. In a field experiment with artificial feeders, foragers were able to learn time intervals and use this ability to anticipate time periods during which feeders were active. Further, interval time-place learning enabled foragers to increase nectar uptake rates. It was concluded that interval time-place learning can help honey bee foragers to adapt to the complex and variable temporal patterns of floral resource environments. V. The study presented in chapter V identified the importance of the honey bee waggle dance communication for the spatiotemporal coordination of honey bee foraging activity in resource environments that can vary from day to day. Consequences of disrupting the instructional component of honey bee dance communication were investigated in eight temperate zone landscapes with different levels of spatiotemporal complexity. While nectar uptake of colonies was not affected, waggle dance communication significantly benefitted pollen harvest irrespective of landscape complexity. I suggest that this is explained by the fact that honey bees prefer to forage pollen in semi-natural habitats, which provide diverse resource species but are sparse and presumably hard to find in intensively managed agricultural landscapes. I conclude that waggle dance communication helps to ensure a sufficient and diverse pollen diet which is crucial for honey bee colony health. VI. In my PhD-project, I could show that honey bee colonies are able to adapt their activities to a seasonally and daily changing environment, which affects resource uptake, colony development, colony health and ultimately colony fitness. Ongoing global change, however, puts timing in honey bee colonies at risk. Climate change has the potential to cause mismatches with the local resource environment. Intensivation of agricultural management with decreased resource diversity and short resource peaks in spring followed by distinctive gaps increases the probability of mismatches. Even the highly efficient foraging system of honey bees might not ensure a sufficiently diverse and healthy diet in such an environment. The global introduction of the parasitic mite V. destructor and the increased exposure to pesticides in intensively managed landscapes further degrades honey bee colony health. This might lead to reduced cognitive capabilities in workers and impact the communication and social organization in colonies, thereby undermining the ability of honey bee colonies to adapt to their environment. N2 - I. Zeitliche Koordination ist äußerst wichtig für Organismen, die in einer variablen und sich wandelnden Umwelt leben. Komplexe Mechanismen, die das Messen von Zeit ermöglichen, sind weit verbreitet und wurden bei vielen Taxa aufgezeigt. Es wird generell angenommen, dass diese Mechanismen Fitnessvorteile verschaffen, indem sie es Organismen ermöglichen, Umweltveränderungen vorherzusehen und sich entsprechen anzupassen. Allerdings gibt es bisher nur sehr wenige Studien zum adaptiven Wert einer guten zeitlichen Koordination. Ziel dieses Dissertations-Projekts war es, Mechanismen der zeitlichen Koordination bei Honigbienen (Apis mellifera) zu erforschen und deren Bedeutung für die Fitness des Honigbienenvolks zu identifizieren. In Kapitel II präsentiere ich meine Studie über die Konsequenzen eines falsch gewählten Zeitpunkts für den Brutbeginn am Ende des Winters und der daraus folgenden gestörten Synchronisation zwischen der Phänologie von Honigbienenvölkern und der lokalen Umwelt. In einem Folgeexperiment wurde die Bedeutung von Umweltfaktoren für das Timing des Brutbeginns untersucht (Kapitel III). Die Studie in Kapitel IV zielt darauf ab, erstmalig den Beweis zu erbringen, dass Honigbienen das „Intervall time-place learning“, d.h. die Fähigkeit, Zeitintervalle zwischen Ereignissen zu lernen und mit deren räumlichen Lage zu assoziieren, beherrschen und, dass diese Fähigkeit beim Sammeln von Ressourcen vorteilhaft ist. Kapitel V untersucht die Fitnessvorteile, die aus dem Austausch von Informationen über ein raumzeitlich heterogenes Ressourcenumfeld zwischen Stockgenossinnen mit Hilfe des Schwänzeltanzes gezogen werden. II. In der Studie, die in Kapitel II präsentiert wird, wurde die Bedeutung des Brutbeginns als entscheidender Punkt für die Phänologie von Honigbienenvölkern in den gemäßigten Breiten untersucht. Honigbienenvölker wurden an zwei klimatisch unterschiedlichen Standorten überwintert. Indem ein Teil der Völker im Spätwinter zwischen den Standorten ausgetauscht wurde, wurde deren Brutbeginn manipuliert und dadurch die Phänologie bezüglich der lokalen Umwelt desynchronisiert. Das verzögern der Phänologie der Völker verminderte deren Fähigkeit die üppige Frühjahrsblüte zu nutzen. Ein früher Brutbeginn andererseits erhöhte die Belastung der Völker durch den Brutparasiten Varroa destructor im Verlauf der Saison, was sich negativ auf die Menge der Arbeiterinnen im Volk auswirkte. Es gibt also entscheidende gegensätzlich wirkende Faktoren, die den optimalen Zeitpunkt des Brutbeginns bestimmen. Die Studie zeigt zudem warum es wichtig ist, die möglichen Folgen des Klimawandels in einem multitrophischen System zu betrachten statt sich auf einfache Interaktionen zu beschränken. Man kann allgemein folgern, dass das Timing des Brutbeginns einen bedeutenden fitnessrelevanten Schritt in der Phänologie von Honigbienenvölkern darstellt, der stark von klimatischen Bedingungen im Spätwinter beeinflusst wird. Verschiebungen und Fehlanpassungen des Brutbeginns, und damit der Phänologie, durch den Klimawandel können ernsthafte negative Konsequenzen für die Fitness von Honigbienenvölkern haben. III. In Kapitel III beleuchte ich die Bedeutung der Umweltfaktoren Umgebungstemperatur und Photoperiode sowie der verstrichenen Zeit auf das Timing des Brutbeginns. Vierundzwanzig überwinternde Honigbienenvölker wurden in Klimakammern untergebracht und auf sechs unterschiedliche Kombinationen von Temperatur- und Lichtregimes verteilt. Der Brutbeginn wurde nicht-invasiv über den Temperaturverlauf auf der Wabe innerhalb der Wintertraube festgestellt. Das Experiment hat gezeigt, dass die Umgebungstemperatur eine entscheidende Rolle beim Timing des Brutbeginns spielt. Allerdings wurde die Reaktion der Völker auf einen Temperaturanstieg vom jeweils vorherrschenden Lichtregime beeinflusst. Zudem deuten die Daten auf die Beteiligung einer inneren Uhr hin. Ich folgere, dass das Timing des Brutbeginns durch ein komplexes System geregelt wird, das wahrscheinlich anfällig für Einflüsse durch den Klimawandel und insbesondere durch Warmwetterphasen im Winter ist. IV. In Kapitel IV meiner Dissertation wird eine Studie präsentiert, die untersucht ob Bienen die Befähigung zum „Intervall time-place learning“ besitzen und ob diese Fähigkeit die Sammeleffizienz in einem dynamischen Ressourcenumfeld verbessert. In einer Feldstudie mit künstlichen Futterquellen zeigten Sammelbienen, dass sie in der Lage waren, Zeitintervalle zu lernen und das Wissen zu nutzen, um die Zeiten vorherzusehen zu denen die Futterquellen aktiv waren. Dieses Lernverhalten ermöglichte es den Sammelbienen, ihre Nektaraufnahmerate zu steigern. Es wurde gefolgert, dass „Intervall time-place learning“ Sammelbienen dabei helfen kann, sich in einem Blühressourcenumfeld mit komplexen und variablen Zeitmustern zurechtzufinden. V. Diese Studie, die in Kapitel V präsentiert wird, untersuchte die Bedeutung der Schwänzeltanzkommunikation der Honigbienen für die raumzeitliche Koordination der Sammelaktivität des Volkes innerhalb eines Ressourcenumfelds, das täglich variieren kann. Die Folgen der Störung der instruktiven Komponenten des Schwänzeltanzes wurden in acht unterschiedlich komplex strukturierten Landschaften innerhalb der gemäßigten Breiten ermessen. Während kein Einfluss auf den Nektarsammelerfolg festgestellt werden konnte, wurde jedoch gezeigt, dass der Pollensammelerfolg, unabhängig von der raumzeitlichen Komplexität der Landschaft, stark von der Schwänzeltanzkommunikation profitiert. Der Grund dafür liegt vermutlich darin, dass Honigbienen vorzugsweise Pollen in halbnatürlichen Habitaten sammeln, die eine hohe Ressourcenvielfalt bieten, aber in intensiv agrarwirtschaftlich genutzten Landschaften eher selten und relativ schwer zu finden sind. Die Studie lässt schließen, dass die Schwänzeltanzkommunikation dabei hilft, eine ausreichende und diverse Pollenernährung zu gewährleisten und damit eine große Rolle für die Gesundheit von Honigbienenvölkern spielt. VI. Ich konnte in meinem Dissertationsprojekt zeigen, dass Honigbienen in der Lage sind ihre Aktivitäten an eine sich jahreszeitlich und täglich verändernde Umwelt anzupassen. Eine gute zeitliche Koordination hat Einfluss auf Sammelerfolg, Volksentwicklung, Gesundheit und letztlich auf die Fitness des Volkes. Allerdings gefährdet der voranschreitende globale Wandel die zeitliche Koordination der Honigbienenvölker. Der Klimawandel hat das Potenzial, zeitliche Anpassungen an die lokale Umwelt zu stören. Die Intensivierung der Landwirtschaft und der damit einhergehende Verlust von Pflanzenvielfalt sowie die kurzen Zeiträume von extrem hohem Ressourcenangebot, gefolgt von einer ausgeprägten Blühlücke, erhöht die Wahrscheinlichkeit, dass zeitlich Fehlanpassungen auftreten. In einer derartigen Umwelt könnte selbst das höchst effiziente Ressourcensammelsystem der Honigbienen nicht mehr genügen, um eine ausreichende, vielfältige und gesunde Ernährung zu gewährleisten. Die globale Verbreitung der parasitischen Varroamilbe durch den Menschen und die erhöhte Belastung durch Pestizide verschlechtert zusätzlich den Gesundheitszustand der Honigbienen. Das wiederum kann sich negativ auf das Lernvermögen und des Weiteren auf die Kommunikation und soziale Organisation der Völker auswirken und dadurch deren Fähigkeit, sich an eine veränderliche Umwelt anzupassen unterwandern. KW - Biene KW - Phänologie KW - Kommunikation KW - Soziale Insekten KW - Apis mellifera KW - foraging KW - brood rearing KW - temperate zones KW - waggle dance KW - hibernation KW - climate change KW - varroa KW - Timing Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-155105 ER - TY - THES A1 - Glogger, Marius T1 - Single-molecule fluorescence microscopy in live \(Trypanosoma\) \(brucei\) and model membranes T1 - Einzelmolekül-Fluoreszenzmikroskopie in lebenden \(Trypanosoma\) \(brucei\) und Modellmembranen N2 - Der eukaryotische Parasit Trypanosoma brucei hat komplexe Strategien entwickelt um der Immunantwort eines Wirtes zu entkommen und eine persistente Infektion innerhalb dessen aufrechtzuerhalten. Ein zentrales Element seiner Verteidigungsstrategie stützt sich auf die Schutzfunktion seines Proteinmantels auf der Zelloberfläche. Dieser Mantel besteht aus einer dichten Schicht aus identischen, Glykosylphosphatidylinositol (GPI)-verankerten variablen Oberflächenglykoproteinen (VSG). Der VSG Mantel verhindert die Erkennung der darunterliegenden, invarianten Epitope durch das Immunsystem. Obwohl es notwendig ist die Funktionsweise des VSG Mantels zu verstehen, vor allem um ihn als mögliches Angriffsziel gegen den Parasiten zu verwenden, sind seine biophysikalischen Eigenschaften bisher nur unzureichend verstanden. Dies ist vor allem der Tatsache geschuldet, dass die hohe Motilität der Parasiten mikroskopische Studien in lebenden Zellen bisher weitestgehend verhinderten. In der vorliegenden Arbeit wird nun hochmoderne Einzelmolekül-Fluoreszenzmikroskopie (EMFM) als Möglichkeit für mikroskopische Untersuchungen im Forschungsbereich der Trypanosomen vorgestellt. Die Arbeit umfasst Untersuchungen der VSG Dynamik unter definierten Bedingungen künstlicher Membransysteme. Es wurde zuerst der Einfluss der lateralen Proteindichte auf die VSG Diffusion untersucht. Experimente mittels Fluoreszenz- Wiederkehr nach irreversiblem Photobleichen und komplementäre Einzelmolekül- Verfolgungs Experimente offenbarten, dass ein molekularer Diffusionsschwellenwert existiert. Über diesem Schwellenwert wurde eine dichteabhänige Reduzierung des Diffusionskoeffizienten gemessen. Eine relative Quantifizierung der rekonstituierten VSGs verdeutlichte, dass der Oberflächenmantel der Trypanosomen sehr nahe an diesem Schwellenwert agiert. Der VSG Mantel ist optimiert um eine hohe Proteindichte bei gleichzeitiger hoher Mobilität der VSGs zu gewährleisten. Des Weiteren wurde der Einfluss der VSG N-Glykosylierung auf die Diffusion des Proteins quantitativ untersucht. Die Messungen ergaben, dass die N-Glykosylierung dazu beiträgt eine hohe Mobilität bei hohen Proteindichten aufrechtzuerhalten. Eine detaillierte Analyse von VSG Trajektorien offenbarte, dass zwei unterschiedliche Populationen frei diffundierender VSGs in der künstlichen Membran vorlagen. Kürzlich wurde entdeckt, dass VSGs zwei strukturell unterschiedliche Konformationen annehmen können. Die Messungen in der Arbeit stimmen mit diesen Beschreibungen überein. Die Ergebnisse der EMFM in künstlichen Membranen wurden durch VSG Einzelmolekül- Verfolgungs Experimente auf lebenden Zellen ergänzt. Es wurde eine hohe Mobilität und Dynamik einzelner VSGs gemessen, was die allgemein dynamische Natur des VSG Mantels verdeutlicht. Dies führte zu der Schlussfolgerung, dass der VSG Mantel auf lebenden Trypanosomen ein dichter und dennoch dynamischer Schutzmantel ist. Die Fähigkeit der VSGs ihre Konformation flexibel anzupassen, unterstützt das Erhalten der Fluidität bei variablen Dichten. Diese Eigenschaften des VSG Mantels sind elementar für die Aufrechterhaltung einer presistenden Infektion eines Wirtes. In dieser Arbeit werden des Weiteren verschiedene, auf Hydrogel basierende Einbettungsmethoden vorgestellt. Diese ermöglichten die Zellimmobilisierung und erlaubten EMFM in lebenden Trypanosomen. Die Hydrogele wiesen eine hohe Zytokompatibilität auf. Die Zellen überlebten in den Gelen für eine Stunde nach Beginn der Immobilisierung. Die Hydrogele erfüllten die Anforderungen der Superresolution Mikroskopie (SRM) da sie eine geringe Autofluoreszenz im Spektralbereich der verwendeten Fluorophore besaßen. Mittels SRM konnte nachgewiesen werden, dass die Hydrogele die Zellen effizient immobilisierten. Als erstes Anwendungsbeispiel der Methode wurde die Organisation der Plasmamembran in lebenden Trypanosomen untersucht. Die Untersuchung eines fluoreszenten Tracers in der inneren Membranschicht ergab, dass dessen Verteilung nicht homogen war. Es wurden spezifische Membrandomänen gefunden, in denen das Molekül entweder vermehrt oder vermindert auftrat. Dies führte zu der Schlussfolgerung, dass diese Verteilung durch eine Interaktion des Tracers mit Proteinen des zellulären Zytoskeletts zustande kam. Die in dieser Arbeit präsentierten Ergebnisse zeigen, dass EMFM erfolgreich für verschiedene biologische Untersuchungen im Forschungsfeld der Trypanosomen angewendet werden kann. Dies gilt zum Beispiel für die Untersuchung von der VSG Dynamik in künstlichen Membransystemen, aber auch für Studien in lebenden Zellen unter Verwendung der auf Hydrogelen basierenden Zelleinbettung. N2 - The eukaryotic parasite Trypanosoma brucei has evolved sophisticated strategies to escape the host immune response and maintain a persistent infection inside a host. One central feature of the parasite’s defense mechanism relies on the shielding function of their surface protein coat. This coat is composed of a dense arrangement of one type of glycosylphosphatidylinositol (GPI)-anchored variant surface glycoproteins (VSGs) which impair the identification of epitopes of invariant surface proteins by the immune system. In addition to the importance of understanding the function of the VSG coat and use it as a potential target to efficiently fight the parasite, it is also crucial to study its biophysical properties as it is not yet understood sufficiently. This is due to the fact that microscopic investigations on living trypanosomes are limited to a great extent by the intrinsic motility of the parasite. In the present study, state-of-the-art single-molecule fluorescence microscopy (SMFM) is introduced as a tool for biophysical investigations in the field of trypanosome research. The work encompasses studies of VSG dynamics under the defined conditions of an artificial supported lipid bilayer (SLB). First, the impact of the lateral protein density on VSG diffusion was systematically studied in SLBs. Ensemble fluorescence after photobleaching (FRAP) and complementary single-particle tracking experiments revealed that a molecular crowding threshold (MCT) exists, above which a density dependent decrease of the diffusion coefficient is measured. A relative quantification of reconstituted VSGs illustrated that the VSG coat of living trypanosomes operates very close to its MCT and is optimized for high density while maintaining fluidity. Second, the impact of VSG N-glycosylation on VSG diffusion was quantitatively investigated. N-glycosylation was shown to contribute to preserving protein mobility at high protein concentrations. Third, a detailed analysis of VSG trajectories revealed that two distinct populations of freely diffusing VSGs were present in a SLB, which is in agreement with the recent finding, that VSGs are able to adopt two main structurally distinct conformations. The results from SLBs were further complemented by single-particle tracking experiments of surface VSGs on living trypanosomes. A high mobility and free diffusion were measured on the cell surface, illustrating the overall dynamic nature of the VSG coat. It was concluded that the VSG coat on living trypanosomes is a protective structure that combines density and mobility, which is supported by the conformational flexibility of VSGs. These features are elementary for the persistence of a stable infection in the host. Different hydrogel embedding methods are presented, that facilitated SMFM in immobilized, living trypanosomes. The hydrogels were found to be highly cytocompatible for one hour after cross-linking. They exhibited low autofluorescence properties in the spectral range of the investigations, making them suitable for super-resolution microscopy (SRM). Exemplary SRM on living trypanosomes illustrated that the hydrogels efficiently immobilized the cells on the nanometer lever. Furthermore, the plasma membrane organization was studied in living trypanosomes. A statistical analysis of a tracer molecule inside the inner leaflet of the plasma membrane revealed that specific membrane domains exist, in which the tracer appeared accumulated or diluted. It was suggested that this distribution was caused by the interaction with proteins of the underlying cytoskeleton. In conclusion, SMFM has been successfully introduced as a tool in the field of trypanosome research. Measurements in model membranes facilitated systematic studies of VSG dynamics on the single-molecule level. The implementation of hydrogel immobilization allowed for the study of static structures and dynamic processes with high spatial and temporal resolution in living, embedded trypanosomes for the first time. KW - Single-molecule fluorescence microscopy KW - Trypanosoma brucei KW - Variant surface glycoprotein KW - Trypanosoma brucei KW - Virulenzfaktor KW - Zelloberfläche KW - Glykoproteine KW - Fluoreszenzmikroskopie Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-169222 ER - TY - THES A1 - Halboth, Florian T1 - Building behavior and nest climate control in leaf-cutting ants: How environmental cues affect the building responses of workers of \(Atta\) \(vollenweideri\) T1 - Bauverhalten und Kontrolle des Nestklimas bei Blattschneiderameisen: Wie Umweltreize die Bauaktivität von Arbeiterinnen der Art \(Atta\) \(vollenweideri\) beeinflussen N2 - The present work investigates the influence of environmental stimuli on the building behavior of workers of the leaf-cutting ant Atta vollenweideri. It focuses on cues related to the airflow-driven ventilation of their giant underground nests, i.e., air movements and their direction, carbon dioxide concentrations and humidity levels of the nest air. First, it is shown that workers are able to use airflow and its direction as learned orientation cue by performing learning experiments with individual foragers using a classical conditioning paradigm. This ability is expected to allow workers to also navigate inside the nest tunnels using the prevailing airflow directions for orientation, for example during tasks related to nest construction and climate control. Furthermore, the influence of carbon dioxide on the digging behavior of workers is investigated. While elevated CO2 levels hardly affect the digging rate of the ants, workers prefer to excavate at locations with lower concentrations and avoid higher CO2 levels when given a choice. Under natural conditions, shifting their digging activity to soil layers containing lower carbon dioxide levels might help colonies to excavate new or to broaden existing nest openings, if the CO2 concentration in the underground rises. It is also shown that workers preferably transport excavated soil along tunnels containing high CO2 concentrations, when carbon dioxide levels in the underground are elevated as well. In addition, workers prefer to carry soil pellets along outflow tunnels instead of inflow tunnels, at least for high humidity levels of the air. The material transported along tunnels providing outflow of CO2-rich air might be used by workers for the construction of ventilation turrets on top of the nest mound, which is expected to promote the wind-induced ventilation and the removal of carbon dioxide from the underground. The climatic conditions inside the nest tunnels also influence the structural features of the turrets constructed by workers on top the nest. While airflow and humidity have no effect on turret structure, outflow of CO2-rich air from the nest causes workers to construct turrets with additional openings and increased aperture, potentially enhancing the airflow-driven gas exchanges within the nest. Finally, the effect of airflow and ventilation turrets on the gas exchanges in Atta vollenweideri nests is tested experimentally on a physical model of a small nest consisting of a single chamber and two nest tunnels. The carbon dioxide clearance rate from the underground was measured depending on both the presence of airflow in the nest and the structural features of the built turrets. Carbon dioxide is removed faster from the physical nest model when air moves through the nest, confirming the contribution of wind-induced flow inside the nest tunnels to the ventilation of Atta vollenweideri nests. In addition, turrets placed on top of one of the tunnel openings of the nest further enhance the CO2 clearance rate and the effect is positively correlated with turret aperture. Taken together, climatic variables like airflow, carbon dioxide and humidity levels strongly affect the building responses of Atta vollenweideri leaf-cutting ants. Workers use these environmental stimuli as orientation cue in the nest during tasks related to excavation, soil transport and turret construction. Although the effects of these building responses on the microclimatic conditions inside the nest remain elusive so far, the described behaviors are expected to allow ant colonies to restore and maintain a proper nest climate in the underground. N2 - Die vorliegende Arbeit untersucht den Einfluss von Umweltreizen auf das Bauverhalten von Blattschneiderameisen der Art Atta vollenweideri. Dabei wird der Fokus auf Luftströmungen und deren Richtung, sowie CO2-Konzentration und Feuchtigkeitsgehalt der Luft gelegt, welche alle im Zusammenhang mit dem wind-induzierten Ventilationssystem der riesigen, unterirdischen Nester stehen. Zunächst wird experimentell mit Hilfe von klassischer Konditionierung gezeigt, dass Arbeiterinnen während des Furagierens lernen können, Luftströmungen sowie deren Richtung zur Orientierung zu nutzen. Diese Fähigkeit sollte Arbeiterinnen auch die Navigation im Nest anhand der auftretenden Strömungsrichtung der Luft, zum Beispiel während Tätigkeiten im Kontext des Nestbaus und der Klimakontrolle, ermöglichen. Weiterhin wird der Einfluss von Kohlenstoffdioxid auf das Grabeverhalten von Arbeiterinnen untersucht. Obwohl CO2 kaum die Grabe-Rate der Ameisen beeinflusst, graben Arbeiterinnen bevorzugt an Orten mit niedrigerer Konzentration und vermeiden höhere Konzentrationen, wenn möglich. Unter natürlichen Bedingungen könnte das Verlagern der Grabeaktivität in Bodenschichten mit niedrigerer CO2-Konzentration Kolonien dabei helfen, neue Nestöffnungen zu graben oder bestehende zu erweitern, wenn die CO2-Konzentration unter der Erde zunimmt. Zusätzlich wird gezeigt, dass Arbeiterinnen ausgegrabene Erde vornehmlich entlang Tunnel transportieren, die eine hohe CO2-Konzentration aufweisen, wenn die CO2-Konzentration im Untergrund ebenfalls erhöht ist. Zudem bevorzugen Arbeiterinnen den Transport von Erdmaterial entlang Ausstrom- anstatt Einstrom-Tunnel, zumindest für hohe Luftfeuchtigkeiten. Material, welches entlang Nesttunnel transportiert wird, aus denen CO2-haltige Luft ausströmt, könnte Arbeiterinnen zum Bau der Ventilationstürme an der Nestoberfläche dienen, was die wind-induzierte Belüftung der Nester verstärken und die Abfuhr von CO2 aus dem Nest fördern sollte. Die klimatischen Bedingungen in den Nesttunneln beeinflussen auch die strukturellen Eigenschaften der Ventilationstürme, die von Arbeiterinnen oberhalb des Nests errichtet werden. Während Luftströmungen und Luftfeuchtigkeit keinen Einfluss auf die Struktur der Türme haben, veranlasst das Ausströmen von CO2-haltiger Luft aus dem Nest Arbeiterinnen dazu, Türme zu bauen, die mehrere Öffnungen und eine vergrößerte Öffnungsfläche besitzen, was den strömungsinduzierten Gasaustausch im Nest begünstigen könnte. Abschließend werden die Auswirkungen von Luftströmungen und Ventilationstürmen auf den Gasaustausch in den Nestern der Blattschneiderameise Atta vollenweideri mit Hilfe eines physikalischen Modells eines kleinen Nests, bestehend aus einer einzelnen Nestkammer und zwei Nesttunneln, untersucht. Die Abfuhr-Rate von CO2 aus dem Untergrund wurde abhängig vom Vorhandensein von Luftströmungen und den strukturellen Eigenschaften der errichteten Ventilationstürme gemessen. CO2 wird schneller aus dem physikalischen Modell entfernt, wenn Luft durch das Nest strömt, was den Beitrag von Luftbewegungen in den Tunneln zur Ventilation der Nester von Atta vollenweideri bestätigt. Ventilationstürme an einer der Nestöffnungen platziert, verstärken zusätzlich die Abfuhr-Rate von CO2 aus dem Nest und dieser Effekt nimmt mit zunehmender Öffnungsfläche der Türme zu. Zusammengefasst beeinflussen Klimavariablen wie Luftströmungen, Kohlenstoffdioxid und Luftfeuchtigkeit stark das Bauverhalten von Blattschneiderameisen der Art Atta vollenweideri. Arbeiterinnen nutzen diese Umweltreize zur Orientierung im Nest während Tätigkeiten, die im Zusammenhang mit Grabeverhalten, dem Transport von Erdmaterial und dem Bau von Ventilationstürmen stehen. Obwohl die Auswirkungen dieser Bauantworten auf die mikroklimatischen Bedingungen im Nest zunächst noch unklar sind, wird angenommen, dass die beschriebenen Verhaltensweisen es Kolonien erlauben, ein geeignetes Nestklima wiederherzustellen und aufrechtzuerhalten. KW - Verhalten KW - Ameisen KW - Nestbau KW - Klima KW - Kohlendioxid KW - building behavior KW - leaf-cutting ants KW - nest climate KW - climate control KW - carbon dioxide KW - airflow KW - Atta vollenweideri Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-161701 ER - TY - THES A1 - König, Julia Maria T1 - Fungal grass endophytes and their dependence on land-use intensity T1 - Gras-Endophyten und ihre Abhängigkeit von der Landnutzungsintensität N2 - Plant-associated fungi can affect the plants‘ interaction with herbivores and other microorganisms. For example, many common forage grasses are infected with Epichloë endophytes. The endophytes systemically colonize the aerial parts of the plants. They produce bioprotective alkaloids that can negatively affect insects and livestock feeding on the grasses, and interact with other fungal species which living from the plants‘ nutrients. Environmental conditions strongly influence Epichloë endophytes. Endophyte-mediated effects on herbivores are more pronounced under increased temperatures and the endophytes may benefit from land use in managed grasslands. Under the framework of the large-scale German project “Biodiversity Exploratories”, I investigated whether infection rates and alkaloid concentrations of Epichloë festucae var. lolii in Lolium perenne (Chapter I) and Epichloë endophytes (E. uncinata, E. siegelii) in Festuca pratensis (Chapter II) depend on land use and season. Further I analysed, whether foliar fungal assemblages of L. perenne are affected by the presence of Epichloë endophytes (Chapter IV). N2 - Mit Pflanzen assoziierte Pilze können die Interaktionen von Pflanzen und Herbivoren, als auch die Kommunikation mit anderen Mikroorganismen beeinflussen. Viele Futter- und Weidegräser sind beispielsweise mit endophytischen Pilzen der Gattung Epichloë infiziert, die die oberirdischen Pflanzenteile der Gräser systemisch besiedeln. Diese Endophyten produzieren bioaktive Alkaloide, die sich negativ auf Fraßfeinde wie Insekten, aber auch Weidetiere, auswirken, und mit anderen pflanzen-assoziierten Pilzarten interagieren. Epichloë Endophyten werden von ihrer äußeren Umwelt stark beeinflusst. So treten die von den Epichloë Endophyten ausgehende Effekte auf Herbivore meist unter erhöhten Temperaturen auf. In agrar-genutzten Grünflächen profitieren die Endophyten möglicherweise auch von der Landnutzung. Im Rahmen des deutschlandweiten Großprojekts „Biodiversitätsexploratorien“ untersuchte ich die Infektionsfrequenzen und Alkaloidkonzentrationen von Epichloë festucae var. lolii in Lolium perenne (Kapitel II) und den Epichloë Endophyten in Festuca pratensis (Kapitel III) in Abhängigkeit von der Landnutzung und Jahreszeit. Des Weiteren untersuchte ich, ob das Auftreten bzw. die Abwesenheit von Epichloë Endophyten einen Einfluss auf die Zusammensetzung der endophytischen Pilzgemeinschaften in Blättern von L. perenne hat (Kapitel IV). KW - Endophytische Pilze KW - Landnutzung KW - fungal endophytes KW - endophytische Pilze KW - land use KW - alkaloids KW - Epichloe KW - Biodiversity Exploratories KW - Alkaloide KW - Biodiversitätsexploratorien KW - Gräser Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-163890 ER - TY - THES A1 - Böck, Julia T1 - Differenzielle Methylierungsanalysen mittels verschiedener Next-Generation Sequencing-basierter Techniken: Die Bedeutung von differenziell methylierten Regionen in der menschlichen Hirnevolution und bei der Krebsentstehung T1 - Differential methylation analysis via various next-generation sequencing technologies: The impact of differentially methylated regions on human brain evolution and cancer development N2 - Die Evolution der Primaten zeigt eine Verbindung zwischen der zunehmenden Komplexität des sozialen Verhaltens und der Vergrößerung des humanen Gehirns, insbesondere des präfrontalen Cortex. Deshalb stellt der präfrontale Cortex bezüglich der Evolution des Menschen eine der interessantesten Strukturen im humanen Gehirn dar. Es wird angenommen, dass nicht allein die Größe, sondern auch die Funktion, vor allem das Zusammenspiel von Neuronen und nicht-neuronalen Zellen, wie z.B. Gliazellen, zur Differenzierung des menschlichen Gehirns von dem rezenter Primaten geführt hat. Daraus lässt sich schließen, dass die Gehirnfunktionen über eine ausgeglichene und gut aufeinander abgestimmte transkriptionelle Landschaft kontrolliert werden, die durch ein zugrundeliegendes genetisches und epigentisches Rückgrat organisiert ist. In dieser Studie wurden das Methylierungsprofil neuronaler und nicht-neuronaler Zellen des präfrontalen Cortex (Brodmann-Areal 10) von drei Menschen und drei Schimpansen miteinander verglichen. Die intra- und interspezifischen differenziell methylierten Regionen (DMRs) waren in bestimmten genomischen Regionen angereichert. Intraspezifische Methylierungsunterschiede zwischen neuronalen und nicht-neuronalen Zellen konnten dreimal häufiger beobachtet werden als interspezifische Unterschiede in den einzelnen Zelltypen. Rund 90% der humanen intraspezifischen DMRs wiesen eine Hypomethylierung in den neuronalen Zellen im Vergleich zu den nicht-neuronalen Zellen auf. In den intraspezifischen DMRs (Mensch und Schimpanse) waren Gene angereichert, die mit verschiedenen neuropsychiatrischen Erkrankungen assoziiert sind. Der Vergleich zwischen Menschen und Schimpanse in den neuronalen und nicht-neuronalen Zelltypen zeigte eine Anreicherung von Genen mit human-spezifischer Histonsignatur. In den nicht-neuronalen Zellen konnten mehr interspezifische DMRs (n=666) detektiert werden als in den neuronalen Zellen (n=96). Ungefähr 95% der nicht-neuronalen interspezifischen DMRs waren im Menschen, im Vergleich zum Schimpansen, hypermethyliert. Daraus ergibt sich der Eindruck, dass mehrere hundert der nicht-neuronalen Gene während der humanen Gehirnevolution einer Methylierungswelle unterlagen. Dies führt zu der Annahme, dass der Einfluss dieser Veränderungen in den nicht-neuronalen Zellen auf die Vergößerung des menschlichen Gehirns bisher stark unterschätzt wurde. Die bekannteste genetische Ursache für erblichen Brust- und Eierstockkrebs sind Mutationen in den Tumorsuppressorgenen (TSG) BRCA1 und BRCA2. Dennoch können nur rund 20-25% der familiären Brustkrebserkrankungen über Keimbahnmutationen in BRCA1/BRCA2 erklärt werden, besonders bei Frauen, deren Erkrankung vor dem vierzigsten Lebensjahr auftritt. Epigenetische Veränderungen, die zu einer aberranten Genexpression führen, spielen ebenfalls eine wichtige Rolle bei der Karzinogenese und der Entwicklung einer Brustkrebserkrankung. Es ist bekannt, dass TSG nicht nur durch den Verlust der Heterozygotie (engl. loss of heterozygosity, LOH) oder homozygote Deletionen, sondern auch durch transkriptionelle Stilllegung via DNA-Methylierung inaktiviert werden können. Im Rahmen dieser Arbeit wurde überprüft, welchen Einfluss aberrante Methylierungsmuster im Promotorbereich von TSG auf die Brustkrebskarzinogenese und die Expression der Gene haben. Für die Quantifizierung der Epimutationen wurden die Promotorbereiche von acht TSG (BRCA1, BRCA2, RAD51C, ATM, PTEN, TP53, MLH1, RB1) und des estrogene receptor (ESR1) Gens, welches eine Rolle in der Tumorprogression spielt, mittels Deep Bisulfite Amplicon Sequencing (DBAS) analysiert. Es wurden Blutproben von zwei unabhängigen BRCA1/BRCA2-mutationsnegativen Brustkrebs (BC)-Patientenkohorten, sowie von zwei unabhängigen alters-gematchten, gesunden Kontrollkohorten untersucht. BC-Kohorte 1 beinhaltet early-onset (EO) BC-Patientinnen. Kohorte 2 enthält BC-Patientinnen mit einem Risiko von >95% eine heterozygote Mutation in BRCA1/BRCA2 (high-risk, HR) zu tragen. Allele mit >50% methylierten CpGs werden als funktionell relevante Epimutationen erachtet, da bekannt ist, dass TSG über eine Methylierung im Promotorbereich transkriptionell stillgelegt werden. Im Vergleich zu ESR1 (Ø Methylierung, 3%), welches die Methylierungslevel eines durchschnittlichen Promotors wiederspiegelt, zeigten die TSG sehr geringe durchschnittliche Methylierungswerte von weniger als 1%. Zudem waren die durchschnittlichen Epimutationsraten (EMR; <0,0001-0,1%) der TSG sehr gering. Mit der Ausnahme von BRCA1, welches eine erhöhte EMR in der BC-Kohorte verglichen zu den Kontrollen (0,31% gegen 0,06%) zeigte, gab es keine signifikanten Gruppenunterschiede zwischen BC-Patientinnen und Kontrollen. Eine von 36 HR BC-Patientinnen zeigte im Vergleich zu den restlichen Proben eine stark erhöhte EMR von 14,7% in BRCA1. Rund ein Drittel (15/44) der EO BC-Patientinnen wiesen eine erhöhte Rate an Einzel-CpG Fehlern in mehreren TSG auf. Die nachfolgenden Expressionsanalysen ergaben eine erniedrigte Expression vieler TSG je analysierter Patientin. Diese Ergebnisse führen zu der Annahme, dass epigenetische Veränderungen in normalen Körperzellen als ein möglicher Indikator für einen gestörten Mechanismus, der für die Aufrechterhaltung des unmethylierten Status und der daraus resultierenden normalen Genexpression zuständig ist, angesehen werden können. Dies kann mit einem erhöhten BC-Risiko assoziiert werden. N2 - The increasing complexity of social behavior along the ascending scale of primates, peaking in human spoken language, is accompanied by an impressive expansion of the human brain, particularly of the prefrontal cortex. Hence, prefrontal cortex appears to be one of the most interesting structures of the human brain, at least from an evolutionary perspective. But not only size but also function, in particular the interplay of neurons and glia cells, are suspected to distinguish the human brain from great apes and other primates. It is plausible to assume that proper brain function is controlled by a coordinated and well balanced transcriptional landscape, orchestrated by the underlying genetic and epigenetic backbone. Using reduced representation bisulfite sequencing (RRBS), we have compared the methylation profiles of neuronal and non-neuronal cells from three human and three chimpanzee prefrontal cortices (Brodmann area 10). Bioinformatic analyses revealed a genome-wide significant enrichment of differentially methylated regions (DMRs) in specific genomic areas. Intraspecific methylation differences between neuronal and non-neuronal cells are about three times more abundant than the interspecific methylation differences. More than 90% of human intraspecific DMRs were hypomethylated in neuronal cells, compared to non-neuronal cells. Intraspecific DMRs showed enrichment of genes associated with different neuropsychiatric disorders. Comparison between humans and chimpanzees yielded enrichments of genes showing human-specific brain histon modification. Interspecific DMRs were much more frequent in non-neuronal cells (n=666) than in neurons (n=96). Approximately 95% of interspecific DMRs in non-neuronal cells were hypermethylated in humans, compared to chimpanzees. It can be assumed that several hundreds of non-neuronal genes underwent a wave of methylation during human brain evolution. The impact of these changes in non-neuronal cells on the extension of the human brain may have been largely underestimated so far. The most prominent genetic cause for inherited breast and ovarian cancer are mutations in the BRCA1 and BRCA2 tumor suppressor genes (TSG). However, BRCA1/BRCA2 germline mutations explain less than 50% of all familial breast cancers, even for women diagnosed before the age of 40 years. It has also been reported that epigenetic abnormalities, which contribute to changes in gene expression, play an important role in carcinogenesis and breast cancer development. To rapidly quantify the number of epimutations in different TSG, in both a qualitative and quantitative manner, we have developed a deep bisulfite sequencing assay targeting the promoter regions of eight TSG (BRCA1, BRCA2, RAD51C, ATM, PTEN, TP53, MLH1 and RB1) and the estrogene receptor (ESR1) gene, which plays a role in tumor progression. We have analyzed blood samples of two independent BRCA1/BRCA2-mutation negative breast cancer (BC) cohorts and two independent age-matched healthy control cohorts. BC cohort 1 represents patients with early-onset BC and BC cohort 2 patients with a high risk to carry a heterozygous mutation. Since it is well known that tumor suppressor genes are transcriptionally silenced by promoter methylation, alleles with >50% methylated CpGs are considered as functionally relevant epimutations. Compared to ESR1, which is representative for an average promoter, TSG exhibited very low (<1%) average methylation levels and also very low mean epimutation rates (EMR; <0.0001% to 0.1%). With exception of BRCA1, which showed an increased EMR in BC (0.31% vs. 0.06%), there was no significant difference between patients and controls detectable. One of 36 HR BC patients showed a dramatically increased EMR (14.7%) in BRCA1. We identified in approximately one third (15 of 44) of EO BC patients increased rates of single CpG methylation errors in multiple TSG. Both EO and HR BC patients exhibited global underexpression of blood TSG. We propose that epigenetic abnormalities in normal body cells are indicative of disturbed mechanisms for maintaining low methylation and appropriate expression levels and may be associated with an increased BC risk. KW - Epigenetik KW - Gehirn KW - Brustkrebs KW - differenzielle Methylierung KW - familiärer Brustkrebs KW - Next-Generation Sequencing KW - Methylierung KW - Evolution KW - menschliche Hirnevolution Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-164220 ER - TY - THES A1 - Kropf, Jan T1 - The Dual Olfactory Pathway in the Honeybee Brain: Sensory Supply and Electrophysiological Properties T1 - Der duale olfaktorische Weg im Gehirn der Honigbiene: Sensorischer Eingang und elektrophysiologische Eigenschaften N2 - The olfactory sense is of utmost importance for honeybees, Apis mellifera. Honeybees use olfaction for communication within the hive, for the identification of nest mates and non-nest mates, the localization of food sources, and in case of drones (males), for the detection of the queen and mating. Honeybees, therefore, can serve as excellent model systems for an integrative analysis of an elaborated olfactory system. To efficiently filter odorants out of the air with their antennae, honeybees possess a multitude of sensilla that contain the olfactory sensory neurons (OSN). Three types of olfactory sensilla are known from honeybee worker antennae: Sensilla trichoidea, Sensilla basiconica and Sensilla placodea. In the sensilla, odorant receptors that are located in the dendritic arborizations of the OSNs transduce the odorant information into electrical information. Approximately 60.000 OSN axons project in two parallel bundles along the antenna into the brain. Before they enter the primary olfactory brain center, the antennal lobe (AL), they diverge into four distinct tracts (T1-T4). OSNs relay onto ~3.000-4.000 local interneurons (LN) and ~900 projection neurons (PN), the output neurons of the AL. The axons of the OSNs together with neurites from LNs and PNs form spheroidal neuropil units, the so-called glomeruli. OSN axons from the four AL input tracts (T1-T4) project into four glomerular clusters. LNs interconnect the AL glomeruli, whereas PNs relay the information to the next brain centers, the mushroom body (MB) - associated with sensory integration, learning and memory - and the lateral horn (LH). In honeybees, PNs project to the MBs and the LH via two separate tracts, the medial and the lateral antennal-lobe tract (m/lALT) which run in parallel in opposing directions. The mALT runs first to the MB and then to the LH, the lALT runs first to the LH and then to the MB. This dual olfactory pathway represents a feature unique to Hymenoptera. Interestingly, both tracts were shown to process information about similar sets of odorants by extracting different features. Individual mALT PNs are more odor specific than lALT PNs. On the other hand, lALT PNs have higher spontaneous and higher odor response action potential (AP) frequencies than mALT PNs. In the MBs, PNs form synapses with ~184.000 Kenyon cells (KC), which are the MB intrinsic neurons. KCs, in contrast to PNs, show almost no spontaneous activity and employ a spatially and temporally sparse code for odor coding. In manuscript I of my thesis, I investigated whether the differences in specificity of odor responses between m- and lALT are due to differences in the synaptic input. Therefore, I investigated the axonal projection patterns of OSNs housed in S. basiconica in honeybee workers and compared them with S. trichoidea and S. placodea using selective anterograde labeling with fluorescent tracers and confocal- microscopy analyses of axonal projections in AL glomeruli. Axons of S. basiconica-associated OSNs preferentially projected into the T3 input-tract cluster in the AL, whereas the two other types of sensilla did not show a preference for a specific glomerular cluster. T3- associated glomeruli had previously been shown to be innervated by mALT PNs. Interestingly, S. basiconica as well as a number of T3 glomeruli lack in drones. Therefore I set out to determine whether this was associated with the reduction of glomeruli innervated by mALT PNs. Retrograde tracing of mALT PNs in drones and counting of innervated glomeruli showed that the number of mALT-associated glomeruli was strongly reduced in drones compared to workers. The preferential projections of S. basiconica-associated OSNs into T3 glomeruli in female workers together with the reduction of mALT-associated glomeruli in drones support the presence of a female-specific olfactory subsystem that is partly innervated by OSNs from S. basiconica and is associated with mALT projection neurons. As mALT PNs were shown to be more odor specific, I suppose that already the OSNs in this subsystem are more odor specific than lALT associated OSNs. I conclude that this female-specific subsystem allows the worker honeybees to respond adequately to the enormous variety of odorants they experience during their lifetime. In manuscript II, I investigated the ion channel composition of mALT and lALT PNs and KCs in situ. This approach represents the first study dealing with the honeybee PN and KC ion channel composition under standard conditions in an intact brain preparation. With these recordings I set out to investigate the potential impact of intrinsic neuronal properties on the differences between m- and lALT PNs and on the sparse odor coding properties of KCs. In PNs, I identified a set of Na+ currents and diverse K+ currents depending on voltage and Na+ or Ca2+ that support relatively high spontaneous and odor response AP frequencies. This set of currents did not significantly differ between mALT and lALT PNs, but targets for potential modulation of currents leading to differences in AP frequencies were found between both types of PNs. In contrast to PNs, KCs have very prominent K+ currents, which are likely to contribute to the sparse response fashion observed in KCs. Furthermore, Ca2+ dependent K+ currents were found, which may be of importance for coincidence detection, learning and memory formation. Finally, I conclude that the differences in odor specificity between m- and lALT PNs are due to their synaptic input from different sets of OSNs and potential processing by LNs. The differences in spontaneous activity between the two tracts may be caused by different neuronal modulation or, in addition, also by interaction with LNs. The temporally sparse representation of odors in KCs is very likely based on the intrinsic KC properties, whereas general excitability and spatial sparseness are likely to be regulated through GABAergic feedback neurons. N2 - Der Geruchssinn ist für die Honigbiene, Apis mellifera, von größter Bedeutung. Honigbienen kommunizieren olfaktorisch, sie können Nestgenossinnen und koloniefremde Honigbienen aufgrund des Geruchs unterscheiden, sie suchen und erkennen Nahrungsquellen olfaktorisch, und Drohnen (männliche Honigbienen) finden die Königin mit Hilfe des Geruchssinns. Deshalb dient die Honigbiene als exzellentes Modell für die Untersuchung hochentwickelter olfaktorischer Systeme. Honigbienen filtern Duftmoleküle mit ihren Antennen aus der Luft. Auf diesen Antennen sitzen Sensillen, die die olfaktorischen sensorischen Neurone (OSN) beinhalten. Drei verschiedene olfaktorische Sensillen existieren bei Arbeiterinnen: Sensilla trichoidea, Sensilla basiconica und Sensilla placodea. In diesen Sensillen sind olfaktorische Rezeptorproteine auf den Dendriten der OSN lokalisiert. Diese Duftrezeptoren wandeln die Duftinformationen in elektrische Informationen um. Die Axone von ca. 60.000 OSN ziehen in zwei Bündeln entlang der Antenne in das Gehirn. Bevor sie das erste olfaktorische Gehirnzentrum, den Antennallobus (AL), erreichen, spalten sie sich in vier distinkte Trakte (T1-T4) auf. Im AL verschalten sie auf 3.000-4.000 lokale Interneurone (LN) und auf etwa 900 Ausgangsneurone des AL, die Projektionsneurone (PN). Die axonalen Endigungen der OSN bilden mit Neuriten der PN und LN kugelförmige Strukturen, die so genannten Glomeruli. Die OSN aus den vier Trakten T1-T4 ziehen in vier zugehörige glomeruläre Cluster. LN verschalten die Information unter den AL Glomeruli, PN leiten olfaktorische Informationen zu den nächsten Gehirnstrukturen, den Pilzkörpern und dem lateralen Horn, weiter. Die Pilzkörper werden als Zentrum für sensorische Integration, Lernen und Gedächtnis gesehen. Die PN, die den AL mit dem Pilzkörper und dem lateralen Horn verbinden, verlaufen in Honigbienen parallel über zwei Bahnen, den medialen und den lateralen Antennallobustrakt (mALT/lALT), aber in entgegengesetzter Richtung. Dieser duale olfaktorische Signalweg wurde in dieser Ausprägung bisher nur in Hymenopteren gefunden. Interessanterweise prozessieren beide Trakte Informationen über die gleichen Düfte. Dabei sind mALT PN duftspezifischer und lALT PN haben höhere spontane Aktionspotentialfrequenzen sowie höhere Aktionspotentialfrequenzen in Antwort auf einen Duftreiz. Im Pilzkörper verschalten PN auf Kenyon Zellen (KC), die intrinsischen Neurone des Pilzkörpers. KC sind im Gegensatz zu PN fast nicht spontan aktiv und kodieren Informationen auf räumlicher und zeitlicher Ebene mit geringer Aktivität. Man spricht von einem so genannten "sparse code". Im ersten Manuskript meiner Doktorarbeit habe ich untersucht, ob die Unterschiede in der Spezifität der Duftantworten zwischen mALT und lALT PN zumindest zum Teil auf Unterschieden im sensorischen Eingang beruhen. Ich habe die axonalen Projektionen der OSN der S. basiconica in Honigbienen untersucht und mit den Projektionen von OSN in S. trichoidea und S. placodea verglichen. Dazu wurden die OSN in den S. basiconica anterograd mit Fluoreszenzmarkern gefärbt und mit mittels konfokaler Mikroskopie untersucht und quantifiziert. Die Axone von OSN aus S. basiconica ziehen präferentiell in das T3 Glomerulus Cluster, die Axone der anderen beiden Sensillentypen zeigen keine Präferenz für ein spezielles Cluster. Es wurde bereits gezeigt, dass die Glomeruli des T3 Clusters von mALT PN innerviert werden. Interessanterweise fehlen S. basiconica und Teile der T3 Glomeruli in Drohnen. Deshalb habe ich untersucht, ob die T3 Reduzierung in Drohnen mit einer Reduzierung der mALT Glomeruli einhergeht. Retrograde Färbungen der mALT PN in Drohnen zeigten, daß die Zahl der mALT Glomeruli in Drohnen gegenüber Arbeiterinnen deutlich reduziert ist. Die Präferenz der OSN der S. basiconica für das T3 Cluster und die reduzierte Anzahl von mALT Glomeruli in Drohnen weisen auf ein arbeiterinnenspezifisches olfaktorisches Subsystem hin, welches aus S. basiconica, T3 Glomeruli und einer Gruppe von mALT PN besteht. Da die mALT PN duftspezifischer als lALT PN sind, vermute ich, dass auch die OSN, die auf mALT PN verschalten, duftspezifischer antworten als OSN die auf lALT PN verschalten. Daraus schließe ich, daß dieses Subsystem den Arbeiterinnen ermöglicht, passend auf die enorme Breite an Duftstoffen zu reagieren, die diese im Laufe ihres arbeitsteiligen Lebens wahrnehmen müssen. Im zweiten Manuskript meiner Doktorarbeit habe ich die Ionenkanalzusammensetzung der mALT PN, der lALT PN und der KC in situ untersucht. Mein Ansatz stellt die erste Studie dar, die die Ionenkanäle von Neuronen in der Honigbiene unter Standardbedingungen an einer intakten Gehirnpräparation untersucht. Mit diesen Messungen versuche ich die potentiellen bioelektrischen Grundlagen für Unterschiede in der Informationskodierung in mALT PN, lALT PN und Kenyon Zellen zu ergründen. In PN konnte ich eine Gruppe von Na+ Ionenkanälen und Na+ abhängigen, Ca2+ abhängigen sowie spannungsabhängigen K+ Ionenkanälen identifizieren, die die Grundlagen für hohe, spontane Aktionspotentialfrequenzen und hohe Duftantwortfrequenzen schaffen. Diese Ströme unterschieden sich nicht grundsätzlich zwischen m- und lALT PN. Jedoch wurden potentielle Ziele für neuronale Modulation gefunden, welche zu unterschiedlichen Aktionspotentialfrequenzen zwischen PN der beiden Trakte führen könnten. Im Gegensatz zu den PN wurden in Kenyon Zellen in der Relation sehr starke K+ Ionenströme gemessen. Diese dienen sehr wahrscheinlich der schnellen Terminierung von Duftantworten, also dem Erzeugen des zeitlichen "sparse code". Außerdem wurden Ca2+ abhängige K+ Kanäle gefunden, die für Koinzidenzdetektion, Lernen und Gedächtnis von Bedeutung sein können. In der Gesamtsicht folgere ich aus meinen Ergebnissen, dass die Unterschiede in der Duftspezifizität zwischen m- und lALT PN überwiegend auf deren sensorischen Eingängen von unterschiedlichen Populationen von OSN und der Verarbeitung über lokale Interneuronen im AL beruht. Die Unterschiede in der Spontanaktivität zwischen mALT und lALT basieren sehr wahrscheinlich auf neuronaler Modulation und/oder Interaktion mit LN. Die zeitliche Komponente des "sparse code" in KC entsteht höchstwahrscheinlich durch die intrinsischen elektrischen Eigenschaften der KC, wohingegen die generelle Erregbarkeit und der räumliche "sparse code" mit großer Wahrscheinlichkeit auf der Regulation durch GABAerge Neurone beruht. KW - Voltage-Clamp-Methode KW - Biene KW - Neuroanatomie KW - Neurobiology KW - Olfaction KW - Geruchssinn Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-108369 ER - TY - THES A1 - Jung, Jamin T1 - Precise timing of the trypanosome cell division cycle T1 - Präzises Timing des trypanosomalen Zellzyklus N2 - African trypanosomes are the causative agents of fatal diseases in humans and livestock. Trypanosomes show a complex lifecycle and shuttle between the transmitting vector, the tsetse (Glossina spec.), and the mammalian host. As a result of this the parasite undergoes tremendous changes in morphology and metabolism to adapt to the different living environments. The two best-studied lifecycle stages are the procyclic forms (PCF) that live in the tsetse fly and the proliferative bloodstream form (BSF) that resides in the mammalian blood. The most conspicuous weapon that trypanosomes use to evade the host immune attack is a dense layer of a single protein type, the variant surface glycoprotein (VSG), which shields the entire cell surface. Immune evasion required high rates of surface membrane turnover and surface coat recycling. Trypanosomes show highly polarised cell architecture with all major eukaryotic organelles (endoplasmic reticulum, Golgi apparatus, endosomal apparatus, lysosome, mitochondrion and peroxisome-like glycosomes) generally present in single copy. Furthermore, trypanosomes possess a single flagellum, which is important not only for cellular motility but also for cell division. How the duplication of all these cellular components is coordinated in order to progresss through the cell division cycle is poorly understood. We used trypanosomes as a model organism due to the relative simplicity and the polarised nature of their cell architecture and determined the duplication of all their compartments. This was only possible due to a new synchronisation approach developed during this project. In the first part of the thesis a precise temporal map of the cell division cycle of the BSF T. brucei cell division cycle was generated. By the use of well-described morphological markers (K/N status, new flagellum outgrowth and DNA synthesis) the position of individual cells was determined with high temporal resolution; this allowed us for the first time to synchronise a cell population in silico without affecting the naturally asynchronous growth. In the second part of the thesis we used this tool to follow duplication events of the Major organelles during progression through the cell division cycle. We precisely determined the time points of organelle duplication and found that it is ordered in trypanosomes. Furthermore we found that BSF T. brucei cells do not grow continuously, cell size start to increase rapidly, during a short period of time, late in the cell division cycle. We speculate that the initiation of cell volume increase is temporally separated from the formation of all secretory organelles in order to ensure maintenance of the protective coat, which must remain intact at all times in order for BSF trypanosomes to be able to evade the host immune response. N2 - Afrikanische Trypanosomen sind Erreger fataler Krankheiten sowohl bei Menschen also auch bei Nutztieren. Trypanosomen weisen einen komplexen Lebenszyklus auf und wechseln hierbei zwischen ihrem Überträger, der Tsetse Fliege (Glossina spec.) und ihrem Säugerwirt. Hieraus resultierend, erlebt der Parasit dramatische Veränderungen der Zellmorphologie und des Zell- metabolismus um sich an die jeweiligen Lebensräume anzupassen. Die zwei am besten unter- suchten Lebensstadien sind die Prozyklische Form (PCF), welche in der Tsetse Fliege vor- kommt und die Blutstrom Form, welche im Säugerwirt zirkuliert. BSF Trypanosomen leben extrazellulär im Säugerblut und sind hier kontinuierlich der Immunabwehr des Wirtes ausge- setzt. Durch einen dichten Proteinmantel eines einzigen Proteintyps, dem variablen Oberflä- chenglykoproteins (VSG) ummantelt der Parasit seine Zelloberfläche und schützt so invariable Proteine vor der Erkennung durch das Immunsystem. Um diesen VSG Mantel aufrecht zu er- halten werden enorm hohe Raten an Oberflächen-membran- und VSG- Recycling benötigt. Trypanosomen weisen eine hoch polarisierte Zellarchitektur auf und die wichtigen Organellen (Endoplasmatisches Retikulum, Golgi Apparat, Endosomaler Apparat, Lysosome, Mitochondri- um und Glykosomen) sind generell in einfacher Kopie vorhanden. Weiterhin besitzen Trypano- somen ein einzenes Flagellum welches sowohl für die Bewegung als auch die Zellteilung des Parasiten von großer Bedeutung ist. All diese Bestandteile müssen während des Zellzyklus verdoppelt werden um zwei lebensfähige Tochterzellen zu generieren. Über die Koordinierung und die Mechanismen der Organellenteilung ist kaum etwas bekannt. Wir nutzen den einfachen Zellaufbau und die polarisierte Zellarchitektur von Trypanosomen um die Verdopplung der zel- lulären Bestandteile zu untersuchen. Dies war jedoch nur durch einen neuen Synchronisie- rungsansatz möglich der im Rahmen dieser Arbeit entwickelt und etabliert wurde. Im ersten Teil der Arbeit wurde eine zeitlich hoch aufgelöste Kartierung des Zellzyklus vorge- nommen. Wir nutzen morphologisch gut beschriebene Marker um die Position einzelner Zellen im Zellzyklus zeitlich sehr genau zu bestimmen, somit kann eine in silico Synchronisierung durchgeführt werde ohne das natürliche Verhalten der Zellpopulation zu beeinflussen. Im zweiten Teil der Arbeit wurde mittels dieser zeitlichen Zellzykluskarte der Teilungszeitpunkt aller wichtigen Organellen bestimmt. Hierbei fanden wir heraus, dass die Teilung der Zellorga- nellen in einer definierten Reihenfolge stattfindet. Weiterhin konnten wir zeigen, dass Trypano- somen nicht kontinuierlich wachsen, die Zelle wächst in einer relativ kurzen Phase, spät im Zellzyklus. Wir vermuten, dass die Teilung der sekretorischen Organellen und das Zellwachs- tums zeitlich voneinander getrennt sind um so den schützenden Proteinmantel, der für das überleben im Blut unabdingbar ist, aufrecht zu erhalten. KW - Zellteilung KW - Trypanosomes KW - Trypanosomen KW - Zellbiologie Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-114932 ER - TY - THES A1 - Bargul, Joel Ltilitan T1 - Characterization of motility and erythrocyte adherence as virulence factors in African trypanosomes T1 - Charakterisierung der Motiliät und Erythrozytenadhärenz als Virulenzfaktoren bei Afrikanischen Trypanosomen N2 - Pathogens causing African animal trypanosomiasis (AAT), the major livestock disease in sub-Saharan Africa, belong to the salivarian group of the African trypanosomes, which are transmitted by the bite of the tsetse fly (Glossina spec.). T. vivax, T. congolense and T. brucei brucei are major pathogens of cattle in particular, causing nagana, with dramatic socio-economic consequences for the affected regions. The parasites additionally have a huge reservoir of other livestock and wild animal hosts. T. brucei, the species which also includes the subspecies pathogenic to humans causing sleeping sickness, has been extensively studied as the cultivatable model trypanosome. But less is known about the other salivarian species, which are not routinely held in culture, if at all possible. A hallmark of trypanosomal lifestyle is the protozoan flagellates incessant motility, which enables them to populate an enormous range of habitats in very diverse hosts. We were now able to characterize, for the first time with high spatiotemporal resolution microscopy, the swimming behaviour and mechanism of the most relevant salivarian species isolated directly from blood. We show the influence of viscosity on the motility of bloodstream form (BSF) cells and simulate their movement between erythrocytes, giving a clear picture of how all analyzed species move under varying environmental conditions. We show that although the basic mechanism of flagellar motility applies to all analyzed species, there are clear morphological differences that produce different reactions to the physical environment. We could define specific conditions for highly increased swimming persistence and speed for compared to the behaviour in standard culture. These results have important implications for the parasites survival strategies in the host, e.g. regarding the capacity for antibody clearance. Although we show all species to effectively remove antibodies from the cell surface, T. congolense differed markedly in its motility behaviour, which gives rise to interesting questions about this species behaviour in the bloodstream. Most of the T. congolense parasites (and to a lesser extent T. vivax) adhere to sheep erythrocytes. Further in vitro studies showed that T. congolense and T. vivax adhered to rabbit, goat, pig and cattle erythrocytes- but binding behaviour was absent in murine blood. Notably, both T. brucei and T. evansi lacked adherence to all studied host erythrocytes. Generally, attachment to blood cells caused reduction of swimming velocities. Judging from its cell architecture, as well as the motility studies in higher media viscosity and in micropillar arrays, T. congolense is not adapted to swim at high speeds in the mammalian bloodstream. Low swimming speeds could allow these purely intravascular parasites to remain bound to the host erythrocytes. N2 - Die wichtigste Viehseuche des subsaharischen Afrika, die afrikanische Trypanosomiasis (AAT), wird durch Pathogene ausgelöst, die zu einer Gruppe der afrikanischen Trypanosomen gehört, die durch den Stich der Tsetsefliege übertragen werden (Salivaria). T. vivax, T. congolense und T. brucei brucei sind die Haupt-Erreger in Rindern, wo sie Nagana verursachen, mit dramatischen sozio-ökonomischen Folgen für die betroffenen Regionen. Die Parasiten haben zusätzlich ein riesiges Reservoir an Zucht- und Wildtieren als Wirte zur Verfügung. T. brucei, die Spezies die auch die humanpathogenen Subspezies umfasst, die Erreger der Schlafkrankheit, ist eingehend als das kultivierbare Trypanosomenmodell untersucht worden, aber es ist weniger über die anderen Salivaria Spezies bekannt, die nicht routinemäßig in Kultur gehalten werden, wenn überhaupt die Möglichkeit besteht. Ein Kennzeichen des trypanosomalen Lebensstils ist die unablässige Motilität der protozooischen Flagellaten, die es ihnen ermöglicht eine riesige Bandbreite an Habitaten in sehr diversen Wirten zu besiedeln. Wir waren in der Lage, zum ersten Mal mit räumlich und zeitlich hochauflösender Mikroskopie, das Schwimmverhalten und den Schwimmmechanismus der wichtigsten Salivaria Spezies zu charakterisieren, die direkt aus dem Blut isoliert wurden. Wir zeigen wie Viskosität die Motilität der Blutstromform (BSF)-Zellen beeinflußt und simulieren deren Bewegung zwischen Erythrozyten. Durch diese Ergebnisse erhalten wir ein klares Bild davon, wie die analysierten Spezies sich unter variierenden experimentellen Bedingungen bewegen. Wir zeigen, dass obwohl der grundlegende Mechanismus der flagellaren Motilität bei allen Spezies gleich ist, es klare morphologische Unterschiede gibt, die verschiedene Reaktionen auf die physikalische Umgebung zur Folge haben. Wir konnten spezifische Konditionen für stark erhöhte Persistenz und Schwimmgeschwindigkeit, im Vergleich zum Verhalten in der Standardkultur, bei T. vivax, T. evansi and T. brucei definieren. Diese Ergebnisse haben wichtige Implikationen für die Überlebensstrategien im Wirt, z.B. bezüglich der Kapazität für die Antikörperentfernung. Obwohl wir zeigen konnten, dass alle Spezies effektiv gebundene Antikörper von ihrer Oberfläche entfernen können, unterscheidet sich T. congolense stark in seinem motilen Verhalten, was interessante Fragen über das Verhalten dieser Spezies im Blutstrom aufwirft. Die meisten T. congolense Parasiten (und in geringerem Ausmaß T. vivax) adhärieren an Erythrozyten des Schafs. Weitere in vitro Versuche zeigten, dass T. congolense und T. vivax auch an Erythrozyten von Kaninchen, Ziege, Schwein und Rind binden, aber nicht im Blut von Mäusen. Interessanterweise adhärierten weder T. brucei noch T. evansi an Erythrozyten irgendeiner Wirts-Spezies. Im Allgemeinen hat die Bindung an Erythrozyten eine Reduktion der Schwimmgeschwindigkeit zur Folge. Nach der Zellarchitektur und dem Verhalten in Medien höherer Viskosität und zwischen Micropillar-Strukturen zu urteilen, ist T. congolense nicht adaptiert, um mit hohen Geschwindigkeiten im Blutstrom von Säugern zu schwimmen. Niedrige Schwimmgeschwindigkeiten könnten diesem rein intravaskulären Parasiten erlauben an den Erythrozyten des Wirts haften zu bleiben. KW - Motiliät KW - African trypanosomes KW - Trypanosomen KW - Erythrozyt KW - motility KW - Antibody clearance KW - erythrocyte adherence KW - Adhäsion KW - Virulenzfaktor KW - Erythrozytenadhärenz Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-115053 ER - TY - THES A1 - Herweg, Jo-Ana T1 - Die Simkania-Vakuole: Die Rolle von ER, retro-/anterograden Protein- und Lipidtransport T1 - The Simkania-vacuole: the role of ER, retro-/anterograde protein- and lipid-transport N2 - Simkania negevensis (Sn) is a Chlamydia-like obligate intracellular bacterium which replicates within a membrane bound vacuole, termed SCV (Simkania-containing vacuole). The SCV is a unique compartment closely associated with ER-membranes, consequently ER-stress is blocked by the bacteria. SCV morphology is similar among epithelial cells (HeLa229, A549, HEp-2) and macrophages (THP1). The SCV represents the first intracellular interface between the host and pathogen which serves as a replication niche. Identifying human and bacterial factors associated with ER-SCV-membranes should contribute towards the understanding of SCV composition and formation as well as interactions with ER or transports. Comparative studies of the SCV should indicate similarities to the chlamydial inclusion since some host cell factors are already known for Chlamydia. In this thesis, a purification protocol has been established that is applicable to HeLa229 and THP1 ER-SCV-membranes and has been further utilized for proteome and lipidome analyses. 302 bacterial and 1178 human proteins composing ER-SCV-membranes and 885 bacterial proteins composing purified Sn have been identified by using label-free mass spectrometry measurements. Among the human factors of non or Sn infected ER-(SCV-) membranes we found 51 enriched or depleted proteins in addition to 57 transport associated ones that indicated infection induced differences among intracellular protein transport. Contrary regulation of retrograde and anterograde transported proteins could be confirmed by using RNA interference and inhibitor tests, whereby Clathrin-associated and COPI vesicles seem to play a central role. Application of Retro-inhibitors, which interfered with retrograde transport processes between endosome to Golgi or early to late endosomes, as well as Bafilomycin A1 (retrograde, late endosomes and lysosomes) and Brefeldin A (anterograde, ER and Golgi) exerted a strong influence on SCV formation, morphology and intracellular lipid transport. By using label-free mass spectrometry measurements and thin layer chromatography we could determine differences in lipid levels within Sn infected cells, ER-SCV-membranes and purified Sn in comparison to uninfected cells. In addition to lipid enrichment or depletion in whole-cell extracts and ER-SCV-membranes, we identified two infection-specific lipids, cholesterol-ß-Dglucoside and PE 30:0. Further, high-throughput RNA interference tests indicated a dependence of Sn infections on endosome to Golgi and Clathrin-associated vesicle transports. Taken together, we were able to identify initial potential SCV-associated proteins and lipids that were connected to bacterial infection. Furthermore, SCV formation and Sn infectiousness depends on retrograde transport processes and therefore also on acquisition of nutrients, such as lipids. N2 - Simkania negevensis (Sn) repliziert als Chlamydia-ähnliches obligat intrazelluläres Bakterium auch in einer membranumschlossenen Vakuole, die als SCV (engl. Simkania-containing vacuole) bezeichnet wird. Die SCV ist ein bis jetzt einzigartiges Kompartiment, das stark mit ER-Membranen assoziiert ist, wobei ER-Stress von den Bakterien blockiert wird. Die Morphologie der SCV scheint dabei in Epithelzellen (HeLa229, A549, HEp-2) als auch in Makrophagen (THP1) gleich zu sein. Die SCV stellt die erste intrazelluläre Berührungsfläche dar, an der Interaktionen zwischen Wirt und Pathogen erfolgen, und dient gleichzeitig als Replikationsnische. Mithilfe der Identifizierung von humanen und bakteriellen Faktoren, die mit der ER-SCV-Membran assoziiert sind, sollten die Zusammensetzung der SCV sowie mögliche Interaktionen mit dem ER oder zellulären Transportwegen ermittelt werden. Vergleichsstudien von SCV-assoziierten Proteinen sollten Ähnlichkeiten zur chlamydialen Inklusion aufzeigen, für die bereits einige interagierende Wirtszellfaktoren beschrieben wurden. In dieser Arbeit wurde ein Aufreinigungsprotokoll etabliert, das sowohl für ER-SCVMembranen aus HeLa229 als auch THP1 geeignet war und für spätere Proteom- oder Lipidomanalysen diente. Über markierungsfreie massenspektrometrische Messungen konnten 302 bakterielle und 1178 humane Proteine in ER-(SCV-) Membranen und 885 bakterielle Proteine in aufgereinigten Sn identifiziert werden. In ER-(SCV-) Membranen von nicht und Sn-infizierten HeLa229 Zellen befanden sich 51 unterschiedlich verteilte und 57 transportassoziierte humane Proteine, die auf infektionsinduzierte Unterschiede beim intrazellulären Proteintransport hindeuteten. Eine entgegengesetzte Regulation von retro- und anterograd transportierten Proteinen konnte mithilfe von RNA-Interferenz und dem Einsatz geeigneter Inhibitoren bestätigt werden, wobei sich zeigte, dass Clathrin-assoziierte und COPI-Vesikel eine zentrale Rolle spielen. Retro-Inhibitoren, die den retrograden Transport zwischen Endosomen zum Golgi oder zwischen frühen und späten Endosomen inhibieren, sowie Bafilomycin A1 (retrograd, späte Endosomen und Lysosomen) und Brefeldin A (anterograd, ER und Golgi), beeinflussten massiv die SCV-Ausbildung, SCV-Morphologie und den intrazellulären Lipidtransport. Über markierungsfreie massenspektrometrische und dünnschichtchromatographische Analysen konnten erste Unterschiede im Lipidvorkommen in Sn-infizierten Zellen, an ER-SCVMembranen und in aufgereinigten Sn im Vergleich zu nicht infizierten Zellen ermittelt werden. Dabei konnten neben An- und Abreicherungen in Gesamtzellextrakten sowie ER-SCVMembranen zwei infektionsspezifische Lipide, Cholesterol-ß-D-Glykosid und PE 30:0, identifiziert werden. Weiterführende umfangreiche RNA-Interferenzstudien weisen darauf hin, dass die Sn-Infektion vom Endosomen-zum-Golgi-Transport und vom Clathrin-assoziierten Vesikeltransport abhängig ist. Zusammenfassend konnten erste mögliche SCV-assoziierte Proteine und Lipide identifiziert werden, die mit der bakteriellen Infektion verbunden waren. Des Weiteren hängen eine stabile SCV-Ausbildung und Sn-Infektivität von verschiedenen retrograden Transportwegen und damit von dem Erwerb von Nährstoffen wie bspw. Lipiden ab. KW - Simkania KW - Vakuole KW - Proteintransport KW - Lipidtransport Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-136844 ER - TY - THES A1 - Schücker, Katharina T1 - The molecular architecture of the meiotic chromosome axis as revealed by super-resolution microscopy T1 - Die molekulare Architektur der meiotischen Chromosomenachse dargestellt mit hochauflösender Mikroskopie N2 - During meiosis proteins of the chromosome axis are important for monitoring chromatin structure and condensation, for pairing and segregation of chromosomes, as well as for accurate recombination. They include HORMA-domain proteins, proteins of the DNA repair system, synaptonemal complex (SC) proteins, condensins and cohesins. To understand more about their function in shaping the meiotic chromosome it is crucial to establish a defined model of their molecular architecture. Up to now their molecular organization was analysed using conventional methods, like confocal scanning microscopy (CLSM) and transmission electron microscopy (TEM). Unfortunately, these techniques are limited either by their resolution power or their localization accuracy. In conclusion, a lot of data on the molecular organization of chromosome axis proteins stays elusive. For this thesis the molecular structure of the murine synaptonemal complex (SC) and the localization of its proteins as well as of three cohesins was analysed with isotropic resolution, providing new insights into their architecture and topography on a nanoscale level. This was done using immunofluorescence labelling in combination with super-resolution microscopy, line profiles and average position determination. The results show that the murine SC has a width of 221.6 nm ± 6.1 nm including a central region (CR) of 148.2 nm ± 2.6 nm. In the CR a multi-layered organization of the central element (CE) proteins was verified by measuring their strand diameters and strand distances and additionally by imaging potential anchoring sites of SYCP1 (synaptonemal complex protein 1) to the lateral elements (LEs). We were able to show that the two LEs proteins SYCP2 and SYCP3 do co-localize alongside their axis and that there is no significant preferential localization towards the inner LE axis of SYCP2. The presented results also predict an orderly organization of murine cohesin complexes (CCs) alongside the chromosome axis in germ cells and support the hypothesis that cohesins in the CR of the SC function independent of CCs. In the end new information on the molecular organization of two main components of the murine chromosome axis were retrieved with nanometer precision and previously unknown details of their molecular architecture and topography were unravelled. N2 - Innerhalb der Meiose sind Proteine der Chromosomenachse wichtig für das Monitoring der Chromatinstruktur und dessen Kondensation, sowie für die Paarung und Trennung der Chromosomen und für eine fehlerfreie Rekombination. Zu diesen Proteinen zählen HORMA-domain Proteine, Proteine des DNA-Reparatur-Systems und des synaptonemalen Komplexes, sowie Kohäsine und Kondesine. Um mehr über ihre Rolle in der Formgebung meiotischer Chromosomen zu erfahren, ist es unabdingbar ein genau definiertes Modell über ihre molekulare Architektur zu erstellen. Bis jetzt wurde ihre molekulare Organisation mit konventionellen Methoden wie dem konfokalen Laser-Scanning-Mikroskop (CLSM) und dem Transmissionselektronenmikroskop (TEM) untersucht. Beide Techniken sind jedoch entweder in ihrer Auflösung oder ihrer Lokalisationsgenauigkeit beschränkt, wodurch viele Daten zur molekularen Organisation der Chromosomenachse noch nicht erfasst werden konnten. Die vorliegende Arbeit untersucht mit isotropischer Auflösung die molekulare Struktur des synaptonemalen Komplexes (SC) der Maus und die Lokalisation seiner Proteine, sowie die Lokalisation von drei Kohäsinen, was neue Einsichten in deren Architektur und Topographie auf der nanomolekularen Ebene erbrachte. Dies gelang durch die Verwendung von Immunfluoreszenzmarkierungen in Kombination mit hochauflösender Mikroskopie, Linienprofilen und durchschnittlicher Positionsbestimmung. Es konnte gezeigt werden, dass der murine SC eine Weite von 221,6 nm ± 6,1 nm besitzt, inklusive einer 148,2 nm ± 2,6 nm weiten zentralen Region (CR). Innerhalb der CR konnte eine mehrschichtige Anordnung der Proteine des zentralen Elements (CE) bestätigt werden. Dies gelang indem ihre Strangdurchmesser und –abstände gemessen worden sind und zusätzlich potentielle Bindestellen von SYCP1 (synaptonemal complex protein 1) an den lateral Elementen des SCs (LEs) abgebildet werden konnten. Zusätzlich konnte gezeigt werden, dass die beiden LE Proteine, SYCP2 und SYCP3, kolokalisieren. Dabei zeigte SYCP2 keine präferentielle Lokalisation im inneren Bereich der LE. Die Ergebnisse der vorliegenden Arbeit deuten auf eine organisierte Anordnung der murinen Kohäsin Komplexe (CCs) entlang der Chromosomenachse in Keimzellen hin und unterstützen die Hypothese, dass Kohäsine innerhalb der CR des SC eine Funktion unabhängig der von CCs haben. Schlussendlich konnten neue Informationen zur molekularen Anordnung von zwei wichtigen Komponenten der murinen Chromosomenachse mit einer Präzision im Nanometerbereich gewonnen werden und bisher nicht bekannte Details ihrer molekularen Architektur und Topographie aufgedeckt werden. KW - Meiose KW - Super-resolution microscopy KW - Meiosis KW - Synaptonemal complex KW - Cohesin complex Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-144199 ER - TY - THES A1 - Schenk [née Wolf], Mariela T1 - Timing of wild bee emergence: mechanisms and fitness consequences T1 - Zeitliche Abstimmung des Bienenschlupfes: Mechanismen und Fitnesskonsequenzen N2 - Solitary bees in seasonal environments have to align their life-cycles with favorable environmental conditions and resources. Therefore, a proper timing of their seasonal activity is highly fitness relevant. Most species in temperate environments use temperature as a trigger for the timing of their seasonal activity. Hence, global warming can disrupt mutualistic interactions between solitary bees and plants if increasing temperatures differently change the timing of interaction partners. The objective of this dissertation was to investigate the mechanisms of timing in spring-emerging solitary bees as well as the resulting fitness consequences if temporal mismatches with their host plants should occur. In my experiments, I focused on spring-emerging solitary bees of the genus Osmia and thereby mainly on O. cornuta and O. bicornis (in one study which is presented in Chapter IV, I additionally investigated a third species: O. brevicornis). Chapter II presents a study in which I investigated different triggers solitary bees are using to time their emergence in spring. In a climate chamber experiment I investigated the relationship between overwintering temperature, body size, body weight and emergence date. In addition, I developed a simple mechanistic model that allowed me to unite my different observations in a consistent framework. In combination with the empirical data, the model strongly suggests that solitary bees follow a strategic approach and emerge at a date that is most profitable for their individual fitness expectations. I have shown that this date is on the one hand temperature dependent as warmer overwintering temperatures increase the weight loss of bees during hibernation, which then advances their optimal emergence date to an earlier time point (due to an earlier benefit from the emergence event). On the other hand I have also shown that the optimal emergence date depends on the individual body size (or body weight) as bees adjust their emergence date accordingly. My data show that it is not enough to solely investigate temperature effects on the timing of bee emergence, but that we should also consider individual body conditions of solitary bees to understand the timing of bee emergence. In Chapter III, I present a study in which I investigated how exactly temperature determines the emergence date of solitary bees. Therefore, I tested several variants degree-day models to relate temperature time series to emergence data. The basic functioning of such degree-day models is that bees are said to finally emerge when a critical amount of degree-days is accumulated. I showed that bees accumulate degree-days only above a critical temperature value (~4°C in O. cornuta and ~7°C in O. bicornis) and only after the exceedance of a critical calendar date (~10th of March in O. cornuta and ~28th of March in O. bicornis). Such a critical calendar date, before which degree-days are not accumulated irrespective of the actual temperature, is in general less commonly used and, so far, it has only been included twice in a phenology model predicting bee emergence. Furthermore, I used this model to retrospectively predict the emergence dates of bees by applying the model to long-term temperature data which have been recorded by the regional climate station in Würzburg. By doing so, the model estimated that over the last 63 years, bees emerged approximately 4 days earlier. In Chapter IV, I present a study in which I investigated how temporal mismatches in bee-plant interactions affect the fitness of solitary bees. Therefore, I performed an experiment with large flight cages serving as mesocosms. Inside these mesocosms, I manipulated the supply of blossoms to synchronize or desynchronize bee-plant interactions. In sum, I showed that even short temporal mismatches of three and six days in bee-plant interactions (with solitary bee emergence before flower occurrence) can cause severe fitness losses in solitary bees. Nonetheless, I detected different strategies by solitary bees to counteract impacts on their fitness after temporal mismatches. However, since these strategies may result in secondary fitness costs by a changed sex ratio or increased parasitism, I concluded that compensation strategies do not fully mitigate fitness losses of bees after short temporal mismatches with their food plants. In the event of further climate warming, fitness losses after temporal mismatches may not only exacerbate bee declines but may also reduce pollination services for later-flowering species and affect populations of animal-pollinated plants. In conclusion, I showed that spring-emerging solitary bees are susceptible to climate change as in response to warmer temperatures bees advance their phenology and show a decreased fitness state. As spring-emerging solitary bees not only consider overwintering temperature but also their individual body condition for adjusting emergence dates, this may explain differing responses to climate warming within and among bee populations which may also have consequences for bee-plant interactions and the persistence of bee populations under further climate warming. If in response to climate warming plants do not shift their phenologies according to the bees, bees may experience temporal mismatches with their host plants. As bees failed to show a single compensation strategy that was entirely successful in mitigating fitness consequences after temporal mismatches with their food plants, the resulting fitness consequences for spring-emerging solitary bees would be severe. Furthermore, I showed that spring-emerging solitary bees use a critical calendar date before which they generally do not commence the summation of degree-days irrespective of the actual temperature. I therefore suggest that further studies should also include the parameter of a critical calendar date into degree-day model predictions to increase the accuracy of model predictions for emergence dates in solitary bees. Although our retrospective prediction about the advance in bee emergence corresponds to the results of several studies on phenological trends of different plant species, we suggest that more research has to be done to assess the impacts of climate warming on the synchronization in bee-plant interactions more accurately. N2 - Solitäre Bienen aus gemäßigten Breiten müssen ihre Lebenszyklen vorteilhaften Umweltbedingungen und –ressourcen angleichen. Deshalb ist ein gutes Timing ihrer saisonalen Tätigkeit von höchster Relevanz. Die meisten Arten aus gemäßigten Breiten nutzen Temperatur als Trigger um ihre saisonale Aktivität zeitlich abzustimmen. Aus diesem Grund kann der Klimawandel die mutualistischen Interaktionen zwischen Bienen- und Pflanzenarten stören, falls steigende Temperaturen das Timing der Interaktionspartner unterschiedlich verändern. Das Ziel dieser Doktorarbeit war es, die Timing-Mechanismen von Frühlingsbienenarten zu untersuchen, sowie die resultierenden Fitnessfolgen, falls zeitliche Fehlabstimmungen zu ihren Wirtspflanzen eintreten sollten. In meinen Experimenten konzentrierte ich mich auf Frühlingsbienenarten der Gattung Osmia (Mauerbienen) und dabei vor allem auf zwei spezielle Arten, nämlich O. cornuta und O. bicornis (in meiner Studie, die ich im Kapitel IV meiner Doktorarbeit präsentiere, untersuchte ich zusätzlich noch eine dritte Bienenart: O. brevicornis). Kapitel II präsentiert eine Studie, in der ich verschiedene Trigger untersuchte, die solitäre Bienen nutzen um ihren Schlupfzeitpunkt im Frühjahr festzulegen. Dazu untersuchte ich in einem Klimakammerexperiment den Zusammenhang zwischen Überwinterungstemperaturen, Körpergröße, Körpergewicht und Schlupftag. Zusätzlich entwickelte ich ein einfaches mechanistisches Modell, welches mir ermöglichte, meine verschiedenen Ergebnisse in einem einheitlichen Rahmen zusammenzufügen. In Kombination mit den empirischen Daten deutet das Modell stark darauf hin, dass Bienen einen strategischen Ansatz verfolgen und genau an dem Tag schlüpfen, der für ihre individuelle Fitnesserwartung am sinnvollsten ist. Ich konnte zeigen, dass dieser gewählte Schlupftag einerseits temperaturabhängig ist, da wärmere Temperaturen den Gewichtverlust der Bienen während der Überwinterung steigern, was wiederum den optimalen Schlupftag auf einem früheren Zeitpunkt verschiebt, andererseits konnte ich ebenfalls zeigen, dass der optimale Schlupfzeitpunkt von der individuellen Körpergröße bzw. dem Körpergewicht der Biene abhängt, da diese ihren Schlupftag danach abstimmen. Meine Daten zeigen, dass es nicht reicht alleinig Temperatureffekte auf das Timing der solitären Bienen zu untersuchen, sondern dass wir ebenfalls die Körperkonditionen der Bienen beachten sollten, um die zeitliche Abstimmung des Bienenschlupfes besser verstehen zu können. In Kapitel III präsentiere ich eine Studie, in der ich den Temperatureinfluss auf den Schlupftermin solitärer Bienen detailreicher untersuchte. Dazu habe ich verschiedene Varianten von Temperatursummen-Modellen getestet, um Temperaturzeitreihen auf Schlupftermine zu beziehen. Die grundlegende Funktionsweise solcher Temperatursummen-Modelle ist, dass der Bienenschlupf auf den Tag prognostiziert wird an dem die Bienen eine bestimmte Menge an Temperatursummen aufsummiert haben. Ich konnte zeigen, dass Bienen Temperatursummen erst ab bestimmten Temperaturen bilden (ab circa 4°C bei O. cornuta und circa 7°C bei O. bicornis) und erst nach Erreichen eines bestimmten Kalendertages (circa 10.März bei O. cornuta und circa 28.März bei O. bicornis). Solch ein bestimmter Kalendertag, vor dessen Erreichen und unabhängig von der aktuellen Temperatur keine Temperatursummen gebildet werden, wird grundsätzlich recht selten verwendet und in Phänologie-Modellen zur Vorhersage des Bienenschlupfes, bis heute auch nur zwei Mal. Zusätzlich benutzte ich mein Modell, um rückwirkend den Bienenschlupf über die letzten Jahrzehnte vorherzusagen. Dazu wandte ich das Modell auf Langzeit-Temperaturdaten an, die von der regionalen Wetterstation in Würzburg aufgezeichnet wurden. Das Modell prognostizierte rückwirkend, dass im Verlauf der letzten 63 Jahre die Bienen ungefähr 4 Tage früher schlüpfen. In Kapitel IV präsentiere ich eine Studie, in der ich untersuchte, inwieweit zeitliche Fehlabstimmungen in Bienen-Pflanzen-Interaktionen die Fitness der solitären Bienen beeinflussen. Dazu führte ich ein Experiment mit großen Flugkäfigen durch, die als Mesokosmos dienten. Innerhalb jedes dieser Mesokosmen manipulierte ich das Angebot an Blüten um Bienen-Pflanzen-Interaktionen wahlweise zu synchronisieren oder zu desynchronisieren. Zusammengefasst konnte ich dabei aufzeigen, dass sogar kurze zeitliche Fehlabstimmungen von drei oder sechs Tagen bereits genügen (Bienen schlüpften zeitlich vor dem Erscheinen der Pflanzen) um bei den Bienen fatale Fitnessfolgen zu verursachen. Nichtsdestotrotz konnte ich bei den Bienen verschiedene Strategien erkennen, mit denen sie Auswirkungen auf ihre Fitness nach zeitlichen Fehlabstimmungen entgegenwirken wollten. Allerdings könnten diese Strategien zu sekundären Fitnessverlusten folgen da sie zu einem veränderten Geschlechterverhältnis oder einem stärkeren Prasitierungsgrad führen. Deshalb konnte ich zusammenfassend feststellen, dass nach zeitlichen Fehlabstimmungen zu den entsprechenden Wirtspflanzen, die Kompensationsstrategien der Bienen nicht ausreichen, um Fitnessverlusste zu minimieren. Im Falle des weiter voranschreitenden Klimawandel könnten die Fitnessverluste der Bienen nicht nur das momentane Bienensterben weiter verschärfen, sondern auch ihren Bestäubungsdienst an später blühenden Arten minimieren und dadurch Populationen von tierbestäubten Pflanzen beeinträchtigen. Zusammenfassend konnte ich zeigen, dass Frühlingsbienenarten anfällig für Klimawandel sind, da sie nach warmen Überwinterungstemperaturen früher schlüpfen und einen geringeren Fitnesszustand aufweisen. Da Frühlingsbienenarten bei der zeitlichen Abstimmung ihres Schlupftages nicht nur Überwinterungstemperaturen, sondern auch ihren individuellen Fitnesszustand beachten, könnte dies unterschiedliche Reaktionen innerhalb oder zwischen Bienenpopulationen auf den Klimawandel erklären. Dies könnte ebenfalls Folgen für Bienen-Pflanzen Interaktionen haben und das weitere Bestehen von Bienenpopulationen gefährden. Falls, durch den Klimawandel bedingt, Pflanzenarten ihre Phänologie nicht in Einklang mit der Phänologie der Bienen verschieben, dann könnten Bienen zeitliche Fehlabstimmungen mit ihren Wirtspflanzen erleben. Da Bienen keine einzige Kompensationsmaßnahme aufzeigen, die erfolgreich Fitnessverlusten entgegenwirken konnte, wären in einem solchen Fall die Folgen für Frühlingsbienenarten fatal. Darüber hinaus konnte ich feststellen, dass Frühlingsbienen einen bestimmten Starttag im Jahr beachten, vor dessen Erreichen sie keine Temperatursummen bilden, unabhängig von der aktuellen Temperatur. Ich schlage deshalb vor, dass weitere Studien ebenfalls einen solchen Starttag in Temperatursummen-Modelle einbauen sollten, um die Genauigkeit zur Berechnung des Bienenschlupfes weiter zu verbessern. Obwohl meine retrospektive Vorhersage zum verfrühten Bienenschlupf ziemlich genau den Ergebnissen von verschiedenen Studien zu den phänologischen Verschiebungen von Pflanzenarten entspricht, schlagen wir vor, dass zusätzliche Untersuchungen konzipiert werden müssen um präzisere Aussagen über die Folgen des Klimawandels auf die Synchronisation der Bienen-Pflanzen-Interaktionen liefern zu können. KW - wild bees KW - timing KW - fitness Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-161565 ER - TY - THES A1 - Mildner, Stephanie T1 - Temporal organization in \(Camponotus\) \(ants\): endogenous clocks and zeitgebers responsible for synchronization of task-related circadian rhythms in foragers and nurses T1 - Zeitliche Organisation bei Camponotus-Ameisen: innere Uhren und die verantwortlichen Zeitgeber für die Synchronisation von Aufgaben-bezogenen circadianen Rhythmen von Fourageuren und Brutpflegerinnen N2 - The rotation of the earth around its axis causes recurring and predictable changes in the environment. To anticipate those changes and adapt their physiology and behavior accordingly, most organisms possess an endogenous clock. The presence of such a clock has been demonstrated for several ant species including Camponotus ants, but its involvement in the scheduling of daily activities within and outside the ant nest is fairly unknown. Timing of individual behaviors and synchronization among individuals is needed to generate a coordinated collective response and to maintain colony function. The aim of this thesis was to investigate the presence of a circadian clock in different worker castes, and to determine the daily timing of their behavioral tasks within the colonies of two nectar-collecting Camponotus species. In chapter I, I describe the general temporal organization of work throughout the worker life in the species Camponotus rufipes. Continuous tracking of behavioral activity of individually- marked workers for up to 11 weeks in subcolonies revealed an age-dependent division of labor between interior and exterior workers. After eclosion, the fairly immobile young ants were frequently nurtured by older nurses, yet they started nursing the brood themselves within the first 48 hours of their life. Only 60% of workers switched to foraging at an age range of one to two weeks, likely because of the reduced needs within the small scale of the subcolonies. Not only the transition rates varied between subcolonies, but also the time courses of the task sequences between workers did, emphasizing the timed allocation of workers to different tasks in response to colony needs. Most of the observed foragers were present outside the nest only during the night, indicating a distinct timing of this behavioral activity on a daily level as well. As food availability, humidity and temperature levels were kept constant throughout the day, the preference for nocturnal activity seems to be endogenous and characteristic for C. rufipes. The subsequent monitoring of locomotor activity of workers taken from the subcolonies revealed the presence of a functional endogenous clock already in one-day old ants. As some nurses displayed activity rhythms in phase with the foraging rhythm, a synchronization of these in-nest workers by social interactions with exterior workers can be hypothesized. Do both castes use their endogenous clock to schedule their daily activities within the colony? In chapter II, I analyzed behavioral activity of C. rufipes foragers and nurses within the social context continuously for 24 hours. As time-restricted access to food sources may be one factor affecting daily activities of ants under natural conditions, I confronted subcolonies with either daily pulses of food availability or ad libitum feeding. Under nighttime and ad libitum feeding, behavioral activity of foragers outside the nest was predominantly nocturnal, confirming the results from the simple counting of exterior workers done in chapter I. Foragers switched to diurnality during daytime feeding, demonstrating the flexible and adaptive timing of a daily behavior. Because they synchronized their activity with the short times of food availability, these workers showed high levels of inactivity. Nurses, in contrast, were active all around the clock independent of the feeding regime, spending their active time largely with feeding and licking the brood. After the feeding pulses, however, a short bout of activity was observed in nurses. During this time period, both castes increasingly interacted via trophallaxis within the nest. With this form of social zeitgeber, exterior workers were able to entrain in-nest workers, a phenomenon observed already in chapter I. Under the subsequent monitoring of locomotor activity under LD conditions the rhythmic workers of both castes were uniformly nocturnal independent of the feeding regime. This endogenous activity pattern displayed by both worker castes in isolation was modified in the social context in adaption to task demands. Chapter III focuses on the potential factors causing the observed plasticity of daily rhythms in the social context in the ant C. rufipes. As presence of brood and conspecifics are likely indicators of the social context, I tested the effect of these factors on the endogenous rhythms of otherwise isolated individuals. Even in foragers, the contact to brood triggered an arrhythmic activity pattern resembling the arrhythmic behavioral activity pattern seen in nurses within the social context. As indicated in chapter I and II, social interaction could be one crucial factor for the synchronization of in nest activities. When separate groups were entrained to phase-shifted light-dark-cycles and monitored afterwards under constant conditions in pairwise contact through a mesh partitioning, both individuals shifted parts of their activity towards the activity period of the conspecific. Both social cues modulated the endogenous rhythms of workers and contribute to the context dependent plasticity in ant colonies. Although most nursing activities are executed arrhythmically throughout the day (chapter II), previous studies reported rhythmic translocation events of the brood in Camponotus nurses. As this behavior favors brood development, the timing of the translocations within the dark nest seems to be crucial. In chapter IV, I tracked translocation activity of all nurses within subcolonies of C. mus. Under the confirmed synchronized conditions of a LD-cycle, the daily pattern of brood relocation was based on the rhythmic, alternating activity of subpopulations with preferred translocation direction either to the warm or to the cold part of the temperature gradient at certain times of the day. Although the social interaction after pulse feeding had noticeable effects on the in-nest activity in C. rufipes (chapter I and II), it was not sufficient to synchronize the brood translocation rhythm of C. mus under constant darkness (e.g. when other zeitgebers were absent). The free-running translocation activity in some nurses demonstrated nevertheless the involvement of an endogenous clock in this behavior, which could be entrained under natural conditions by other potential non-photic zeitgebers like temperature and humidity cycles. Daily cycling of temperature and humidity could not only be relevant for in-nest activities, but also for the foraging activity outside the nest. Chapter V focuses on the monitoring of field foraging rhythms in the sympatric species C. mus and C. rufipes in relation to abiotic factors. Although both species had comparable critical thermal limits in the laboratory, foragers in C. mus were strictly diurnal and therefore foraged under higher temperatures than the predominant nocturnal foragers in C. rufipes. Marking experiments in C. rufipes colonies with higher levels of diurnal activity revealed the presence of temporally specialized forager subpopulations. These results suggest the presence of temporal niches not only between the two Camponotus species, but as well between workers within colonies of the same species. In conclusion, the temporal organization in colonies of Camponotus ants involves not only the scheduling of tasks performed throughout the worker life, but also the precise timing of daily activities. The necessary endogenous clock is already functioning in all workers after eclosion. Whereas the light-dark cycle and food availability seem to be the prominent zeitgebers for foragers, nurses may rely more on non-photic zeitgeber like social interaction, temperature and humidity cycles. N2 - Die Drehung der Erde um ihre eigene Achse erzeugt wiederkehrende und vorhersehbare Umweltschwankungen. Um diese Schwankungen zu antizipieren und Physiologie sowie Verhalten entsprechend anzupassen, besitzen fast alle Organismen eine innere Uhr. Bei einigen Ameisenarten, Camponotus Ameisen eingenommen, wurde die Präsenz einer inneren Uhr bereits bestätigt. Wie diese Uhr allerdings zur zeitlichen Abstimmung der Tagesaktivitäten innerhalb und außerhalb des Ameisennestes genutzt wird, war bis jetzt weitestgehend unbekannt. Für die Koordination einer kollektiven Verhaltensantwort und die Aufrechterhaltung der Kolonie ist dabei nicht nur die zeitliche Steuerung vom Verhalten Einzelner notwendig, sondern auch eine Synchronisation zwischen den Arbeiterinnen. Das Ziel dieser Doktorarbeit war es, die mögliche Präsenz einer inneren Uhr in verschiedenen Arbeiterkasten zu untersuchen, und die zeitliche Koordination von Tagesaktivitäten dieser Kasten innerhalb der Kolonien zweier Camponotus Ameisenarten zu bestimmen. In Kapitel I beschreibe ich die grundlegende zeitliche Organisation der Arbeitsteilung im Laufe des Arbeiterinnenlebens in der Art Camponotus rufipes. Mithilfe einer lückenlosen Verfolgung der Tagesaktivitäten von individuell markierten Tieren in Subkolonien über bis zu 11 Wochen konnte eine altersabhängige Arbeitsteilung zwischen Innen- und Außendienstarbeiterinnen nachgewiesen werden. Nach dem Schlüpfen wurden die eher unbeweglichen jungen Ameisen oft durch ältere Brutpflegerinnen versorgt, engagierten sich dann aber schon innerhalb der ersten 48 Stunden ihres Lebens selbst in der Brutpflege. Wahrscheinlich wegen der verminderten Notwendigkeit zur ausgedehnten Futtersuche innerhalb der kleinen Versuchskolonien wechselten nur 60% der Innendienstarbeiterinnen nach ein bis zwei Wochen zum Fouragieren außerhalb der Kolonie. Nicht nur variierte der Prozentsatz des Verhaltensübergangs von Brutpflegerin zur Sammlerin zwischen den Subkolonien, sondern auch innerhalb der Subkolonien unterschieden sich Arbeiterinnen im Zeitverlauf der Aufgabenfolge. Diese Ergebnisse betonen die gezielte, zeitliche Zuweisung von Arbeiterinnen zu einer bestimmten Arbeiterkaste je nach Bedarf der Kolonie. In diesem Experiment waren die Sammlerinnen vorwiegend nur während der Nachtphase außerhalb der Kolonie aktiv, was wiederum eine genaue zeitliche Koordination des Sammelverhaltens auf Tagesbasis zeigt. Da die Futterverfügbarkeit sowie Temperatur- und Luftfeuchte über den Tag hinweg konstant gehalten wurden, scheint die bevorzugte Nachtaktivität endogen und charakteristisch für C. rufipes zu sein. Durch das anschließende Monitoring der Lokomotoraktivität von Arbeiterinnen aus diesen Subkolonien konnte gezeigt werden, dass schon einen Tag alte Ameisen eine funktionierende innere Uhr besitzen. Der Aktivitätsrhythmus mancher Brutpflegerinnen war dabei in Phase mit dem Sammelrhythmus der Kolonie, weswegen man von einer Synchronisation dieser Inndienstarbeiterinnen durch soziale Interaktion mit Außendienstarbeiterinnen ausgehen kann. Doch nutzen beide Kasten ihre innere Uhr auch, um ihre Tagesaktivitäten innerhalb der Kolonie zeitlich abzustimmen? In Kapitel II habe ich die Verhaltensaktivität von C. rufipes Futtersammlerinnen und Brutpflegerinnen in ihrem sozialen Umfeld kontinuierlich für 24 Stunden verfolgt. Da der beschränkte Zugriff zu Futterquellen einer der Faktoren sein könnte, der die Tagesaktivitäten von Ameisen in der Natur beeinflusst, wurden Subkolonien entweder nur pulsartig oder ad libitum gefüttert. Während der Nacht- und ad libitum Fütterung waren Sammlerinnen vorwiegend nachtaktiv, was die Ergebnisse der simplen Zählung von Außendiensttieren in Kapitel I bestätigt. Während der Tagesfütterung wurden die Sammlerinnen tagaktiv, was die flexible und adaptive zeitliche Anpassung dieses täglichen Verhaltens veranschaulicht. Unabhängig von der Fütterungszeit waren Brutpflegerinnen rund um die Uhr aktiv, wobei sie die größte Zeit mit Fütterung und Säuberung der Brut verbrachten. Jedoch konnte kurz nach den Fütterungspulsen ein kurzer Aktivitätsanstieg verzeichnet werden, welcher auf die erhöhte Interaktion durch Trophallaxis mit den Sammlerinnen zurückzuführen ist. Wie bereits schon in Kapitel I angedeutet, können Außendiensttiere mithilfe dieses sozialen Zeitgebers Arbeiterinnen im Nest synchronisieren. Im anschließenden Monitoring der Lokomotoraktivität unter Licht-Dunkel-Bedingungen waren alle rhythmischen Arbeiterinnen einheitlich nachtaktiv, unabhängig von der vorausgegangen Fütterungszeit. Damit werden die endogenen Aktivitätsmuster, die beide Kasten in Isolation zeigen, im sozialen Kontext in Anpassung an die speziellen Anforderungen an die Kasten modifiziert. Schwerpunkt des Kapitels III ist die Untersuchung der potentiellen Faktoren, die die gezeigte Plastizität der Tagesrhythmen bei Ameisen der Art C. rufipes bedingen. Da unter anderem das Vorhandensein von Brut und Artgenossinnen sozialen Kontext signalisieren können, wurde der Effekt dieser Faktoren auf die endogenen Rhythmen von ansonsten isolierten Individuen untersucht. Selbst in Sammlerinnen verursachte der Kontakt zu Brut ein arrhythmisches Aktivitätsmuster, welches dem Verhaltensmuster von Brutpflegerinnen innerhalb der Kolonie gleicht. Wie schon in Kapitel I und II deutlich wurde, könnten soziale Interaktionen einen wesentlichen Beitrag zur Synchronisation der Nestaktivitäten leisten. Dazu wurden Gruppen getrennt voneinander mit phasenverschobenen Licht-Dunkel-Zyklen entraint, und Tiere anschließend in paarweisem Kontakt durch ein Netzgitter aufgezeichnet. Beide Individuen verschoben einen Teil ihrer Aktivität in die Aktivitätsperiode des Partners. Damit modulierten beide getesteten sozialen Faktoren die endogenen Rhythmen der Arbeiterinnen, was letztendlich zur kontextabhängigen Plastizität der Rhythmen in Ameisenkolonien beiträgt. Obwohl Brutpflegerinnen die meisten Verhaltensweisen arrhythmisch während des ganzen Tages ausüben (Kapitel II), zeigten vorangegangene Studien rhythmische Brutverlagerungen bei Brutpflegerinnen der Camponotus-Arten. Da dieses Verhalten die Brutentwicklung fördert, scheint das Timing der Verlagerungen innerhalb des ansonsten dunklen Nestes essentiell zu sein. In Kapitel IV verfolgte ich die Verlagerungsaktivität von allen Brutpflegerinnen in Subkolonien der Art C. mus. Unter den gesichert synchronisierten Bedingungen eines LD-Zykluses basierte das Brutverlagerungsmuster auf der rhythmischen, abwechselnden Aktivität von zwei Subpopulationen mit bevorzugter Verlagerungsrichtung in entweder den warmen oder kalten Bereich des Temperaturgradienten zu bestimmten Tageszeiten. Obwohl die soziale Interaktion nach Pulsfütterung einen deutlichen Einfluss auf die Nestaktivität bei C. rufipes hatte (Kapitel I und II), reichte diese Interaktion nicht aus um den Brutverlagerungsrhythmus bei C. mus innerhalb des dunklen Nests (d.h. unter Abwesenheit sonstiger Zeitgeber) zu synchronisieren. Nichtsdestotrotz zeigte der Freilauf der Brutverlagerungsrhythmen in einigen Brutpflegerinnen die Beteiligung einer inneren Uhr, welche durch anderweitige nicht-photische Zeitgeber wie Temperatur- und Feuchtigkeitszyklen synchronisiert werden könnte. Tageszyklen in Temperatur und Feuchtigkeit könnten nicht nur relevant sein für Aktivitäten innerhalb des Nests, sondern auch für die Fouragieraktivität außerhalb des Nests. In Kapitel V wurden Fouragierrhythmen im Freiland bei den sympatrisch vorkommenden Ameisenarten C. mus und C. rufipes in Abhängigkeit von abiotischen Faktoren betrachtet. Obwohl die beiden Arten unter Laborbedingungen ähnliche kritische Temperaturgrenzen aufzeigten, waren die Fourageure der Art C. mus strikt tagaktiv und sammelten deswegen unter höheren Temperaturen Futter als die vorwiegend nachtaktiven Fourageure der Art C. rufipes. Bei C. rufipes Kolonien mit erhöhter Tagaktivität wiesen Markierexperimente das Vorkommen von zeitlich spezialisierten Fourageur-Subpopulationen nach. Damit deuten die Ergebnisse nicht nur das Vorkommen von unterschiedlichen zeitlichen Nischen innerhalb der beiden Camponotus-Arten an, sondern auch zwischen Arbeiterinnen von Kolonien derselben Art. Zusammenfassend gesehen umspannt die zeitliche Organisation in Kolonien der Camponotus-Ameisen nicht nur die zeitliche Planung der Aufgaben, die über das Arbeiterinnenleben hinweg ausgeführt werden, sondern auch das genaue Terminierung von Tagesaktivitäten. Bereits nach dem Schlüpfen besitzen allen Arbeiterinnen eine funktionsfähige und für die zeitliche Organisation notwendige innere Uhr. Während der Licht-Dunkel-Zyklus und Futterverfügbarkeit die bedeutenden Zeitgeber für Fourageure zu sein scheinen, könnten Brutpflegerinnen eher auf nicht-photische Zeitgeber wie soziale Interaktion, Temperatur- und Feuchtigkeitszyklen angewiesen sein. KW - circadian clocks KW - behavioral rhythms KW - Camponotus KW - zeitgeber KW - division of labor KW - temporal organization KW - zeitliche Organisation Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-149382 ER - TY - THES A1 - Bartossek, Thomas T1 - Structural and functional analysis of the trypanosomal variant surface glycoprotein using x-ray scattering techniques and fluorescence microscopy T1 - Strukturelle und funktionale Analyse des variablen Oberflächenproteins von Trypanosoma brucei mithilfe vön Röntgenstreutechniken und Fluoreszenzmikroskopie N2 - Trypanosoma brucei is an obligate parasite and causative agent of severe diseases affecting humans and livestock. The protist lives extracellularly in the bloodstream of the mammalian host, where it is prone to attacks by the host immune system. As a sophisticated means of defence against the immune response, the parasite’s surface is coated in a dense layer of the variant surface glycoprotein (VSG), that reduces identification of invariant epitopes on the cell surface by the immune system to levels that prevent host immunity. The VSG has to form a coat that is both dense and mobile, to shield invariant surface proteins from detection and to allow quick recycling of the protective coat during immune evasion. This coat effectively protects the parasite from the harsh environment that is the mammalian bloodstream and leads to a persistent parasitemia if the infection remains untreated. The available treatment against African Trypanosomiasis involves the use of drugs that are themselves severely toxic and that can lead to the death of the patient. Most of the drugs used as treatment were developed in the early-to-mid 20th century, and while developments continue, they still represent the best medical means to fight the parasite. The discovery of a fluorescent VSG gave rise to speculations about a potential interaction between the VSG coat and components of the surrounding medium, that could also lead to a new approach in the treatment of African Trypanosomiasis that involves the VSG coat. The initially observed fluorescence signal was specific for a combination of a VSG called VSG’Y’ and the triphenylmethane (TPM) dye phenol red. Exchanging this TPM to a bromo-derivative led to the observation of another fluorescence effect termed trypanicidal effect which killed the parasite independent of the expressed VSG and suggests a structurally conserved feature between VSGs that could function as a specific drug target against T. b. brucei. The work of this thesis aims to identify the mechanisms that govern the unique VSG’Y’ fluorescence and the trypanocidal effect. Fluorescence experiments and protein mutagenesis of VSG’Y’ as well as crystallographic trials with a range of different VSGs were utilized in the endeavour to identify the binding mechanisms between TPM compounds and VSGs, to find potentially conserved structural features between VSGs and to identify the working mechanisms of VSG fluorescence and the trypanocidal effect. These trials have the potential to lead to the formulation of highly specific drugs that target the parasites VSG coat. During the crystallographic trials of this thesis, the complete structure of a VSG was solved experimentally for the first time. This complete structure is a key component in furthering the understanding of the mechanisms governing VSG coat formation. X-ray scattering techniques, involving x-ray crystallography and small angle x-ray scattering were applied to elucidate the first complete VSG structures, which reveal high flexibility of the protein and supplies insight into the importance of this flexibility in the formation of a densely packed but highly mobile surface coat. N2 - Trypanosoma brucei ist ein eukaryotischer Parasit welcher bei Menschen und Nutztieren schwere Krankheiten auslöst. Der Protist lebt extrazellulär im Blutstrom seines Säugetier-Wirtes, in welchem er unter konstantem Angriff durch das Wirts-Immunsystem steht. Als ausgeklügelte Methode zur Umgehung der Immunantwort besitzt der Parasit einen dichten Oberflächenmantel des variablen Oberflächen-Glycoproteins (VSG), welcher die Identifikation invariabler Oberflächenproteine durch das Immunsystem erschwert und Wirts-Immunität gegen den Parasiten verhindert. Der gebildete VSG-Mantel muss gleichzeitig eine hohe Dichte besitzt, um invariable Oberflächenproteine vor Immundetektion zu beschützen, und eine hohe Mobilität aufweisen, um ein schnelles Recycling des Schutzmantels während Immunantworten zu gewährleisten. Dieser Mantel schützt den Parasiten effektiv vor dem Wirts-Immunsystem und führt bei fehlender Behandlung des Patienten zur persistenten Parasitemie durch Trypanosoma brucei. Die verfügbaren Behandlung gegen die Afrikanische Trypanosomiasis beinhaltet die Benutzung von Medikamenten welche ihrerseits z.T. stark toxisch sind und den Tod des Patienten verursachen können. Ein Großteil der verfügbaren Medikamente wurden zu Beginn des letzten Jahrhunderts entwickelt und stellen trotz anhaltenden Entwicklungen noch immer die beste Lösung im Kampf gegen den Parasiten dar. Die Entdeckung eines fluoreszierenden VSGs deutete auf eine Interaktionen zwischen dem VSG Mantel und Bestandteilen des umgebenden Medium hin, welche die Entwicklung von Medikamenten mit dem VSG Mantel als Drug Target ermöglichen könnte. Das ursprünglich beobachtete Fluoreszenz-Signal war spezifisch für eine Kombination eines VSG namens VSG’Y’ und dem Triphenylmethan (TPM) Phenolrot. Der Austausch von Phenolrot gegen ein Brom-Derivat führte zur Beobachtung eines weiteren Fluoreszenz-Effekts, welcher unabhängig vom exprimierten VSG auftritt und letal für den Parasiten ist. Dieser so genannten Trypanozide Effekt lässt auf konservierte Strukturen schließen, welche von allen VSGs geteilt werden und als hochspezifisches Drug Target gegen T. b. brucei fungieren könnten. Das Ziel der vorliegenden Arbeit war es, die Mechanismen zu identifizieren, welche die einzigartige VSG’Y’-Fluoreszenz und den Trypanoziden Effekt auslösen. Fluoreszenz-Experimente und Protein-Mutagenese von VSG’Y’, sowie röntgenkristallographische Analysen mit mehreren unterschiedlichen VSGs wurden in dem Bestreben durchgeführt, die Bindung zwischen VSGs und TPMs zu charakterisieren, potentiell konservierte Strukturen von VSGs zu finden und die Mechanismen der einzigartigen VSG’Y’-Fluoreszenz und des Trypanoziden Effekts zu identifizieren. Diese Arbeiten haben das Potenzial die Formulierung hochspezifischer Medikamente mit VSGs als Drug Target anzutreiben. Im Rahmen der kristallographischen Analysen wurden die ersten vollständigen VSG Strukturen ermittelt, welche eine hohe Bedeutung für das Verständnis über die Bildung des VSG-Mantels haben. Die VSG Strukturen wurden u.a. per Röntgenkristallographie und Kleinwinkel-Röntgenstreuung aufgeschlüsselt und zeigten dass VSGs ein hohes Maß an Flexibilität besitzen. Diese Flexibilität ist wichtig für die Bildung eines dichten und hochmobilen VSG-Mantels. KW - Trypanosoma brucei brucei KW - Röntgenstrukturanalyse KW - Röntgen-Kleinwinkelstreuung KW - Mutagenese KW - Fluoreszenzmikroskopie KW - Variables Oberflächen Glycoprotein KW - VSG Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-144775 ER - TY - THES A1 - Joschinski, Jens T1 - Is the phenology of pea aphids (\(Acyrthosiphon\) \(pisum\)) constrained by diurnal rhythms? T1 - Wird die Phänologie der Erbsenblattlaus (\(Acyrthosiphon\) \(pisum\)) durch Tag-/Nachtrhythmik limitiert? N2 - The rotation of the earth leads to a cyclic change of night and day. Numerous strategies evolved to cope with diurnal change, as it is generally advantageous to be synchronous to the cyclic change in abiotic conditions. Diurnal rhythms are regulated by the circadian clock, a molecular feedback loop of RNA and protein levels with a period of circa 24 hours. Despite its importance for individuals as well as for species interactions, our knowledge of circadian clocks is mostly confined to few model organisms. While the structuring of activity is generally adaptive, a rigid temporal organization also has its drawbacks. For example, the specialization to a diurnal pattern limits the breadth of the temporal niche. Organisms that are adapted to a diurnal life style are often poor predators or foragers during night time, constraining the time budget to only diurnal parts of the day/night cycle. Climate change causes shifts in phenology (seasonal timing) and northward range expansions, and changes in season or in latitude are associated with novel day length – temperature correlations. Thus, seasonal organisms will have some life history stages exposed to novel day lengths, and I hypothesized that the diurnal niche determines whether the day length changes are beneficial or harmful for the organism. I thus studied the effects of day length on life-history traits in a multi-trophic system consisting of the pea aphid Acyrthosiphon pisum and predatory larvae of Chrysoperla carnea (common green lacewing) and Episyrphus balteatus (marmalade hoverfly). In order to identify the mechanisms for phenological constraints I then focused on diurnal rhythms and the circadian clock of the pea aphid. Aphids reacted to shorter days with a reduced fecundity and shorter reproductive period. Short days did however not impact population growth, because the fitness constraints only became apparent late in the individual’s life. In contrast, E. balteatus grew 13% faster in the shorter day treatment and preyed on significantly more aphids, whereas C. carnea grew 13% faster under longer days and the elevation of predation rates was marginally significant. These results show that day length affects vital life-history traits, but that the direction and effect size depends on species. I hypothesized that the constraints or fitness benefits are caused by a constricted or expanded time budget, and hence depend on the temporal niche. E. balteatus is indeed night-active and C. carnea appears to be crepuscular, but very little data exists for A. pisum. Hence, I reared the pea aphid on an artificial diet and recorded survival, moulting and honeydew excretion. The activity patterns were clearly rhythmic and molting and honeydew excretion were elevated during day-time. Thus, the diurnal niche could explain the observed, but weak, day length constraints of aphids. The diurnal niche of some organisms is remarkably flexible, and a flexible diurnal niche may explain why the day length constrains were relatively low in A. pisum. I thus studied its circadian clock, the mechanism that regulates diurnal rhythms. First, I improved an artificial diet for A. pisum, and added the food colorant Brilliant Blue FCF. This food colorant stained gut and honeydew in low concentration without causing mortalities, and thus made honeydew excretion visible under dim red light. I then used the blue diet to raise individual aphids in 16:08 LD and constant darkness (DD), and recorded honeydew excretion and molting under red light every three hours. In addition, we used a novel monitoring setup to track locomotor activity continuously in LD and DD. Both the locomotor rhythm and honeydew excretion of A. pisum appeared to be bimodal, peaking in early morning and in the afternoon in LD. Both metabolic and locomotor rhythm persisted also for some time under constant darkness, indicating that the rhythms are driven by a functional circadian clock. However, the metabolic rhythm damped within three to four days, whereas locomotor rhythmicity persisted with a complex distribution of several free-running periods. These results fit to a damped circadian clock that is driven by multiple oscillator populations, a model that has been proposed to link circadian clocks and photoperiodism, but never empirically tested. Overall, my studies integrate constraints in phenological adaptation with a mechanistic explanation. I showed that a shorter day length can constrain some species of a trophic network while being beneficial for others, and linked the differences to the diurnal niche of the species. I further demonstrated that a flexible circadian clock may alleviate the constraints, potentially by increasing the plasticity of the diurnal niche. N2 - Die Rotation der Erde bedingt den zyklischen Wechsel von Tag und Nacht. Verschiedene Anpassungen an den täglichen Wechsel evolvierten, da es generell von Vorteil ist, mit der abiotischen Umwelt synchron zu sein. Die Tagesrhythmik wird von der circadianen Uhr reguliert, einem molekularen Rückkopplungsmechanismus auf RNA- und Protein- Ebene mit einer Periode von etwa 24 Stunden. Trotz der Bedeutung der circadianen Uhr, sowohl für Individuen als auch für Wechselwirkungen mit anderen Arten, ist unser Wissen auf wenige Modellorganismen beschränkt. Während die Strukturierung von Aktivitätsmustern im Wesentlichen adaptiv ist, kann eine strenge zeitliche Organisation auch Nachteile mit sich bringen. Zum Beispiel limitiert die Spezialisierung auf ein Aktivitätsmuster die Breite der zeitlichen Nische. So können tagaktive Organismen häufig nur schlecht in Dunkelheit Nahrung finden, so dass das Zeitbudget von der Tageszeit begrenzt wird. Der Klimawandel führt zu Veränderungen der Phänologie (saisonales Timing) und zur Ausbreitung der Arten Richtung Norden, und Veränderungen in der Phänologie oder im Breitengrad sind mit neuen Korrelationen von Tageslänge und Temperatur verknüpft. Daher werden einige Stadien im Lebenszyklus saisonaler Organismen neuen Tageslängen ausgesetzt. Ich habe die Hypothese aufgestellt, dass die zeitliche Nische bestimmt, ob Veränderungen in der Tageslänge für den Organismus von Vorteil oder von Nachteil sind. Daher untersuchte ich die Effekte von Tageslängen auf den Lebenszyklus von Arten in einem multi-trophischen System, bestehend aus der Erbsenblattlaus, Acyrthosiphon pisum und räuberisch lebenden Larven von Chrysoperla carnea (Gemeine Florfliege) und Episyrphus balteatus (Hainschwebfliege). Um die Mechanismen der Einschränkungen in der Phänologie zu verstehen, untersuchte ich anschließend die Tagesrhythmik und die circadiane Uhr der Erbsenblattlaus. Die Blattläuse haben auf Kurztagbedingungen mit einer niedrigeren Fruchtbarkeit und kürzerer Reproduktionsspanne reagiert. Kurze Tage haben jedoch nicht das Populationswachstum beeinflusst, da die Leistungseinbußen erst spät im Leben des Individuums in Erscheinung traten. Im Gegensatz zur Erbsenblattlaus entwickelte sich E. balteatus 13 % schneller unter Kurztagbedingungen und erbeutete signifikant mehr Blattläuse, während C. carnea sich 13% schneller unter Langtagbedingungen entwickelte und marginal höhere Prädationsraten erreichte. Diese Ergebnisse verdeutlichen, dass die Tageslänge wichtige Aspekte der Biologie von Organismen beeinflusst, aber dass die Richtung und Bedeutung von Art zu Art unterschiedlich ist. Ich nahm an, dass die Einschränkungen oder Vorteile durch ein verkleinertes oder vergrößertes Zeitbudget bestimmt werden und daher von der zeitlichen Nische abhängen. E. balteatus ist tatsächlich nachtaktiv, während C. carnea dämmerungsaktiv zu sein scheint. Für A. pisum existieren hingegen nur unzureichende Daten. Daher züchtete ich A. pisum auf künstlichem Futter und nahm Überlebensraten, Häutung und Honigtau-Exkretion auf. Die Aktivitätsmuster waren deutlich rhythmisch, und Häutung und Honigtau-Exkretion waren tagsüber erhöht. Daher kann die Einnischung auf Tagaktivität die beobachteten (aber schwachen) Nachteile kurzer Tage erklären. Die zeitliche Nische einiger Organismen ist überraschend flexibel, und eine flexible zeitliche Nische könnte erklären warum der Effekt der Tageslänge relativ niedrig in A. pisum war. Daher untersuchte ich die circadiane Uhr der Erbsenblattlaus, da dieser Mechanismus die Aktivitätsmuster reguliert. Zunächst verbesserte ich das künstliche Futter von A. pisum, und fügte den Lebensmittelfarbstoff Brilliant Blue FCF hinzu. Dieser Farbstoff färbte sowohl Magen als auch Honigtau in niedriger Konzentration ohne die Mortalität zu erhöhen, und machte dadurch die Exkretion von Honigtau unter schwachem Rotlicht sichtbar. Ich nutzte anschließend das blaue Futter, um Blattläuse einzeln in 16:08 LD und konstanter Dunkelheit (DD) aufzuziehen und dabei Honigtau-Exkretion und Häutungen alle drei Stunden zu notieren. Zusätzlichen nutzten wir ein neues Überwachungssystem um Aktivitätsmuster in Lokomotion kontinuierlich in LD und DD aufzuzeichnen. Sowohl Lokomotionsrhythmik als auch Honigtau-Exkretion von A. pisum schienen bimodal zu sein und erreichten früh morgens und nachmittags ihre Maximalwerte in LD. Beide Rhythmen bestanden auch unter konstanter Dunkelheit einige Zeit fort, was aufzeigt, dass die Rhythmen von einer funktionierenden inneren Uhr gesteuert werden. Die Rhythmik im Metabolismus dämpfte jedoch innerhalb von drei bis vier Tagen aus, während die Lokomotionsrhythmik mit einer komplexen Verteilung verschiedener free-running-Perioden fortbestand. Diese Ergebnisse passen zu einer gedämpften circadianen Uhr, die aus mehreren Oszillatorgruppen besteht. Ein solches Modell wurde vorgeschlagen, um circadiane Uhren mit Messungen der Photoperiode zu verknüpfen, aber nie empirisch überprüft. Insgesamt verbinden meine Versuche die Einschränkungen phänologischer Anpassung mit einer mechanistischen Erklärung. Ich zeigte, dass kürzere Tage einigen Arten eines trophischen Netzwerks Vorteile, anderen jedoch Nachteile verschafften, und habe diese Unterschiede auf die zeitliche Nische der Arten zurückgeführt. Ich habe weiterhin gezeigt, dass eine flexible circadiane Uhr die Nachteile lindern kann, möglicherweise weil sie die Plastizität der zeitlichen Nische erhöht. KW - Tagesrhythmus KW - Phänologie KW - pea aphid KW - artificial diet KW - Acyrthosiphon pisum Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-148099 ER - TY - JOUR A1 - Mall, David A1 - Larsen, Ashley E. A1 - Martin, Emily A. T1 - Investigating the (mis)match between natural pest control knowledge and the intensity of pesticide use JF - Insects N2 - Transforming modern agriculture towards both higher yields and greater sustainability is critical for preserving biodiversity in an increasingly populous and variable world. However, the intensity of agricultural practices varies strongly between crop systems. Given limited research capacity, it is crucial to focus efforts to increase sustainability in the crop systems that need it most. In this study, we investigate the match (or mismatch) between the intensity of pesticide use and the availability of knowledge on the ecosystem service of natural pest control across various crop systems. Using a systematic literature search on pest control and publicly available pesticide data, we find that pest control literature is not more abundant in crops where insecticide input per hectare is highest. Instead, pest control literature is most abundant, with the highest number of studies published, in crops with comparatively low insecticide input per hectare but with high world harvested area. These results suggest that a major increase of interest in agroecological research towards crops with high insecticide input, particularly cotton and horticultural crops such as citrus and high value-added vegetables, would help meet knowledge needs for a timely ecointensification of agriculture. KW - ecological intensification KW - insecticides KW - agroecology KW - agricultural intensity KW - biological pest control KW - crop KW - study system Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158977 VL - 9 IS - 1 ER - TY - THES A1 - Dejure, Francesca Romana T1 - Investigation of the role of MYC as a stress responsive protein T1 - Untersuchung der Rolle von MYC als stress-reguliertes Protein N2 - The transcription factor MYC is deregulated in over 70% of all human tumors and, in its oncogenic form, plays a major role in the cancer metabolic reprogramming, promoting the uptake of nutrients in order to sustain the biosynthetic needs of cancer cells. The research presented in this work aimed to understand if MYC itself is regulated by nutrient availability, focusing on the two major fuels of cancer cells: glucose and glutamine. Initial observations showed that endogenous MYC protein levels strongly depend on the availability of glutamine, but not of glucose. Subsequent analysis highlighted that the mechanism which accounts for the glutamine-mediated regulation of MYC is dependent on the 3´-untranslated region (3´-UTR) of MYC. Enhanced glutamine utilization by tumors has been shown to be directly linked to MYC oncogenic activity and MYC-dependent apoptosis has been observed under glutamine starvation. Such effect has been described in experimental systems which are mainly based on the use of MYC transgenes that do not contain the 3´-UTR. It was observed in the present study that cells are able to survive under glutamine starvation, which leads to cell cycle arrest and not apoptosis, as previously reported. However, enforced expression of a MYC transgene, which lacks the 3´-UTR, strongly increases the percentage of apoptotic cells upon starvation. Evaluation of glutamine-derived metabolites allowed to identify adenosine nucleotides as the specific stimulus responsible for the glutamine-mediated regulation of MYC, in a 3´-UTR-dependent way. Finally, glutamine-dependent MYC-mediated effects on RNA Polymerase II (RNAPII) function were evaluated, since MYC is involved in different steps of global transcriptional regulation. A global loss of RNAPII recruitment at the transcriptional start site results upon glutamine withdrawal. Such effect is overcome by enforced MYC expression under the same condition. This study shows that the 3´UTR of MYC acts as metabolic sensor and that MYC globally regulates the RNAPII function according to the availability of glutamine. The observations presented in this work underline the importance of considering stress-induced mechanisms impinging on the 3´UTR of MYC. N2 - In über 70% aller Krebserkrankungen ist der Transkriptionsfaktor MYC dereguliert. Dabei spielt onkogenes MYC unter anderem eine wichtige Rolle bei der Umprogrammierung metabolischer Prozesse indem es z.B. die Aufnahme von Nährstoffen wie Glutamin oder Glukose fördert, um den veränderten Bedürfnissen an den Stoffwechsel der Krebszellen Rechnung zu tragen. Die im Rahmen dieser Arbeit erzielten Ergebnisse zeigen, dass auch das MYC-Protein selbst durch die Verfügbarkeit von Nährstoffen in der Zelle reguliert werden kann. Erste Beobachtungen zeigten, dass die endogenen MYC Proteinlevel stark von der Verfügbarkeit von Glutamin, jedoch nicht von Glucose, abhängen. Weiterführende Experimente ergaben außerdem, dass der Mechanismus, der der Glutamin vermittelten Regulation von MYC zugrunde liegt, abhängig von der 3´-untranslatierten Region (3´-UTR) der MYC-mRNA ist. Es konnte bereits gezeigt werden, dass in Tumoren die verstärkte Nutzung von Glutamin in direktem Zusammenhang mit der onkogenen Aktivität von MYC steht und Zellen unter Glutaminentzug MYC-abhängig Apoptose einleiten. Diese Effekte wurden in experimentellen Systemen beschrieben, die auf einer Überexpression eines MYCTransgenes basierten, welches keine 3´-UTR enthält. In dieser Arbeit konnte jedoch beobachtet werden, dass Zellen, die ohne Glutamin kultiviert wurden, in der Lage waren zu überleben, da entgegen den Resultaten vorausgegangener Studien, ein Arrest des Zellzyklus und nicht Apoptose eingeleitet wurde. Die verstärkte Expression eines MYCTransgenes ohne 3´-UTR, erhöhte jedoch auch unter diesen Bedingungen die Anzahl apoptotischer Zellen. Weiterhin war es möglich Adenosin, für dessen Biosynthese Glutamin notwendig ist, als Stimulus zu identifizieren, der für die 3´-UTR abhängige Regulation von MYC verantwortlich ist. Da MYC in verschiedene Schritte der globalen Regulation der Transkription eingebunden ist, wurden abschließend die durch MYC vermittelten Glutaminabhängigen Effekte auf die RNA-Polymerase II (RNAPII) untersucht. Dabei zeigte sich, dass es nach Glutaminentzug zu einem globalen Verlust der Rekrutierung von RNAPII zu den Transkriptionsstartstellen kommt, was durch eine verstärkte MYC-Expression wieder aufgehoben werden kann. Zusammenfassend konnte in dieser Arbeit gezeigt werden, dass die 3´-UTR von MYC als metabolischer Sensor fungiert und dass MYC in Abhängigkeit der Verfügbarkeit von Glutamin global die RNAPII Funktion reguliert. Diese Studie hebt weiterhin die Bedeutung der 3´-UTR von MYC für die Vermittlung stressinduzierter Feedback-Mechanismen hervor. KW - cancer KW - metabolism KW - MYC KW - Myc KW - Stress KW - Metabolismus KW - Genregulation KW - Glutamin Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-158587 ER -