@article{LamatschTrifonovSchoriesetal.2011, author = {Lamatsch, D. K. and Trifonov, V. and Schories, S. and Epplen, J. T. and Schmid, M. and Schartl, M.}, title = {Isolation of a Cancer-Associated Microchromosome in the Sperm-Dependent Parthenogen Poecilia formosa}, series = {Cytogenetic and Genome Research}, volume = {135}, journal = {Cytogenetic and Genome Research}, number = {2}, issn = {1424-8581}, doi = {10.1159/000331271}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-196785}, pages = {135-142}, year = {2011}, abstract = {In the asexual all-female fish species Poecilia formosa, the Amazon molly, supernumerary chromosomes have frequently been found in both laboratory-reared and wild-caught individuals. While wild-caught individuals with B chromosomes are phenotypically indifferent from conspecifics, individuals carrying B chromosomes from recent introgression events in the laboratory show phenotypic changes. Former analyses showed that the expression of a pigment cell locus is associated with the presence of these B chromosomes. In addition, they contain a so far unidentified locus that confers a higher susceptibility to tumor formation in the presence of pigmentation pattern. Isolation by microdissection and hybridization to metaphase chromosomes revealed that they contain one or several sequences with similarity to a highly repetitive pericentromeric and subtelomeric sequence in A chromosomes. Isolation of one particular sequence by AFLP showed that the B chromosomes contain at least 1 copy of an A-chromosomal region which is highly conserved in the whole genus Poecilia, i.e. more than 5 million years old. We propose it to be a single copy sequence.}, language = {en} } @article{StiebKelberWehneretal.2011, author = {Stieb, Sara Mae and Kelber, Christina and Wehner, R{\"u}diger and R{\"o}ssler, Wolfgang}, title = {Antennal-Lobe Organization in Desert Ants of the Genus Cataglyphis}, series = {Brain, Behavior and Evolution}, volume = {77}, journal = {Brain, Behavior and Evolution}, number = {3}, issn = {0006-8977}, doi = {10.1159/000326211}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-196815}, pages = {136-146}, year = {2011}, abstract = {Desert ants of the genus Cataglyphis possess remarkable visual navigation capabilities. Although Cataglyphis species lack a trail pheromone system, Cataglyphis fortis employs olfactory cues for detecting nest and food sites. To investigate potential adaptations in primary olfactory centers of the brain of C. fortis, we analyzed olfactory glomeruli (odor processing units) in their antennal lobes and compared them to glomeruli in different Cataglyphis species. Using confocal imaging and 3D reconstruction, we analyzed the number, size and spatial arrangement of olfactory glomeruli in C. fortis, C.albicans, C.bicolor, C.rubra, and C.noda. Workers of all Cataglyphis species have smaller numbers of glomeruli (198-249) compared to those previously found in olfactory-guided ants. Analyses in 2 species of Formica - a genus closely related to Cataglyphis - revealed substantially higher numbers of olfactory glomeruli (c. 370), which is likely to reflect the importance of olfaction in these wood ant species. Comparisons between Cataglyphis species revealed 2 special features in C. fortis. First, with c. 198 C. fortis has the lowest number of glomeruli compared to all other species. Second, a conspicuously enlarged glomerulus is located close to the antennal nerve entrance. Males of C. fortis possess a significantly smaller number of glomeruli (c. 150) compared to female workers and queens. A prominent male-specific macroglomerulus likely to be involved in sex pheromone communication occupies a position different from that of the enlarged glomerulus in females. The behavioral significance of the enlarged glomerulus in female workers remains elusive. The fact that C. fortis inhabits microhabitats (salt pans) that are avoided by all other Cataglyphis species suggests that extreme ecological conditions may not only have resulted in adaptations of visual capabilities, but also in specializations of the olfactory system.}, language = {en} } @article{SeherNickelMuelleretal.2011, author = {Seher, Axel and Nickel, Joachim and Mueller, Thomas D. and Kneitz, Susanne and Gebhardt, Susanne and Meyer ter Vehn, Tobias and Schlunck, Guenther and Sebald, Walter}, title = {Gene expression profiling of connective tissue growth factor (CTGF) stimulated primary human tenon fibroblasts reveals an inflammatory and wound healing response in vitro}, series = {Molecular Vision}, volume = {17}, journal = {Molecular Vision}, number = {08. Okt}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-140189}, pages = {53-62}, year = {2011}, abstract = {Purpose: The biologic relevance of human connective tissue growth factor (hCTGF) for primary human tenon fibroblasts (HTFs) was investigated by RNA expression profiling using affymetrix (TM) oligonucleotide array technology to identify genes that are regulated by hCTGF. Methods: Recombinant hCTGF was expressed in HEK293T cells and purified by affinity and gel chromatography. Specificity and biologic activity of hCTGF was confirmed by biosensor interaction analysis and proliferation assays. For RNA expression profiling HTFs were stimulated with hCTGF for 48h and analyzed using affymetrix (TM) oligonucleotide array technology. Results were validated by real time RT-PCR. Results: hCTGF induces various groups of genes responsible for a wound healing and inflammatory response in HTFs. A new subset of CTGF inducible inflammatory genes was discovered (e.g., chemokine [C-X-C motif] ligand 1 [CXCL1], chemokine [C-X-C motif] ligand 6 [CXCL6], interleukin 6 [IL6], and interleukin 8 [IL8]). We also identified genes that can transmit the known biologic functions initiated by CTGF such as proliferation and extracellular matrix remodelling. Of special interest is a group of genes, e.g., osteoglycin (OGN) and osteomodulin (OMD), which are known to play a key role in osteoblast biology. Conclusions: This study specifies the important role of hCTGF for primary tenon fibroblast function. The RNA expression profile yields new insights into the relevance of hCTGF in influencing biologic processes like wound healing, inflammation, proliferation, and extracellular matrix remodelling in vitro via transcriptional regulation of specific genes. The results suggest that CTGF potentially acts as a modulating factor in inflammatory and wound healing response in fibroblasts of the human eye.}, language = {en} } @article{SchleuningFarwigPetersetal.2011, author = {Schleuning, Matthias and Farwig, Nina and Peters, Marcell K. and Bergsdorf, Thomas and Bleher, B{\"a}rbel and Brandl, Roland and Dalitz, Helmut and Fischer, Georg and Freund, Wolfram and Gikungu, Mary W. and Hagen, Melanie and Garcia, Francisco Hita and Kagezi, Godfrey H. and Kaib, Manfred and Kraemer, Manfred and Lung, Tobias and Naumann, Clas M. and Schaab, Gertrud and Templin, Mathias and Uster, Dana and W{\"a}gele, J. Wolfgang and B{\"o}hning-Gaese, Katrin}, title = {Forest Fragmentation and Selective Logging Have Inconsistent Effects on Multiple Animal-Mediated Ecosystem Processes in a Tropical Forest}, series = {PLoS ONE}, volume = {6}, journal = {PLoS ONE}, number = {11}, doi = {10.1371/journal.pone.0027785}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-140093}, pages = {e27785}, year = {2011}, abstract = {Forest fragmentation and selective logging are two main drivers of global environmental change and modify biodiversity and environmental conditions in many tropical forests. The consequences of these changes for the functioning of tropical forest ecosystems have rarely been explored in a comprehensive approach. In a Kenyan rainforest, we studied six animal-mediated ecosystem processes and recorded species richness and community composition of all animal taxa involved in these processes. We used linear models and a formal meta-analysis to test whether forest fragmentation and selective logging affected ecosystem processes and biodiversity and used structural equation models to disentangle direct from biodiversity-related indirect effects of human disturbance on multiple ecosystem processes. Fragmentation increased decomposition and reduced antbird predation, while selective logging consistently increased pollination, seed dispersal and army-ant raiding. Fragmentation modified species richness or community composition of five taxa, whereas selective logging did not affect any component of biodiversity. Changes in the abundance of functionally important species were related to lower predation by antbirds and higher decomposition rates in small forest fragments. The positive effects of selective logging on bee pollination, bird seed dispersal and army-ant raiding were direct, i.e. not related to changes in biodiversity, and were probably due to behavioural changes of these highly mobile animal taxa. We conclude that animal-mediated ecosystem processes respond in distinct ways to different types of human disturbance in Kakamega Forest. Our findings suggest that forest fragmentation affects ecosystem processes indirectly by changes in biodiversity, whereas selective logging influences processes directly by modifying local environmental conditions and resource distributions. The positive to neutral effects of selective logging on ecosystem processes show that the functionality of tropical forests can be maintained in moderately disturbed forest fragments. Conservation concepts for tropical forests should thus include not only remaining pristine forests but also functionally viable forest remnants.}, language = {en} } @article{WagnerFischerThomaetal.2011, author = {Wagner, Toni U. and Fischer, Andreas and Thoma, Eva C. and Schartl, Manfred}, title = {CrossQuery: A Web Tool for Easy Associative Querying of Transcriptome Data}, series = {PLoS ONE}, volume = {6}, journal = {PLoS ONE}, number = {12}, doi = {10.1371/journal.pone.0028990}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134787}, pages = {e28990}, year = {2011}, abstract = {Enormous amounts of data are being generated by modern methods such as transcriptome or exome sequencing and microarray profiling. Primary analyses such as quality control, normalization, statistics and mapping are highly complex and need to be performed by specialists. Thereafter, results are handed back to biomedical researchers, who are then confronted with complicated data lists. For rather simple tasks like data filtering, sorting and cross-association there is a need for new tools which can be used by non-specialists. Here, we describe CrossQuery, a web tool that enables straight forward, simple syntax queries to be executed on transcriptome sequencing and microarray datasets. We provide deep-sequencing data sets of stem cell lines derived from the model fish Medaka and microarray data of human endothelial cells. In the example datasets provided, mRNA expression levels, gene, transcript and sample identification numbers, GO-terms and gene descriptions can be freely correlated, filtered and sorted. Queries can be saved for later reuse and results can be exported to standard formats that allow copy-and-paste to all widespread data visualization tools such as Microsoft Excel. CrossQuery enables researchers to quickly and freely work with transcriptome and microarray data sets requiring only minimal computer skills. Furthermore, CrossQuery allows growing association of multiple datasets as long as at least one common point of correlated information, such as transcript identification numbers or GO-terms, is shared between samples. For advanced users, the object-oriented plug-in and event-driven code design of both server-side and client-side scripts allow easy addition of new features, data sources and data types.}, language = {en} } @article{CeteciXuCetecietal.2011, author = {Ceteci, Fatih and Xu, Jiajia and Ceteci, Semra and Zanucco, Emanuele and Thakur, Chitra and Rapp, Ulf R.}, title = {Conditional Expression of Oncogenic C-RAF in Mouse Pulmonary Epithelial Cells Reveals Differential Tumorigenesis and Induction of Autophagy Leading to Tumor Regression}, series = {Neoplasia}, volume = {13}, journal = {Neoplasia}, number = {11}, doi = {10.1593/neo.11652}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134347}, pages = {1005-1018}, year = {2011}, abstract = {Here we describe a novel conditional mouse lung tumor model for investigation of the pathogenesis of human lung cancer. On the basis of the frequent involvement of the Ras-RAF-MEK-ERK signaling pathway in human non-small cell lung carcinoma (NSCLC), we have explored the target cell availability, reversibility, and cell type specificity of transformation by oncogenic C-RAF. Targeting expression to alveolar type II cells or to Clara cells, the two likely precursors of human NSCLC, revealed differential tumorigenicity between these cells. Whereas expression of oncogenic C-RAF in alveolar type II cells readily induced multifocal macroscopic lung tumors independent of the developmental state, few tumors with type II pneumocytes features and incomplete penetrance were found when targeted to Clara cells. Induced tumors did not progress and were strictly dependent on the initiating oncogene. Deinduction of mice resulted in tumor regression due to autophagy rather than apoptosis. Induction of autophagic cell death in regressing lung tumors suggests the use of autophagy enhancers as a treatment choice for patients with NSCLC.}, language = {en} } @article{PillaiHeidemannKumaretal.2011, author = {Pillai, Deepu R. and Heidemann, Robin M. and Kumar, Praveen and Shanbhag, Nagesh and Lanz, Titus and Dittmar, Michael S. and Sandner, Beatrice and Beier, Christoph P. and Weidner, Norbert and Greenlee, Mark W. and Schuierer, Gerhard and Bogdahn, Ulrich and Schlachetzki, Felix}, title = {Comprehensive Small Animal Imaging Strategies on a Clinical 3 T Dedicated Head MR-Scanner; Adapted Methods and Sequence Protocols in CNS Pathologies}, series = {PLoS ONE}, volume = {6}, journal = {PLoS ONE}, number = {2}, doi = {10.1371/journal.pone.0016091}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134193}, pages = {e16091}, year = {2011}, abstract = {Background: Small animal models of human diseases are an indispensable aspect of pre-clinical research. Being dynamic, most pathologies demand extensive longitudinal monitoring to understand disease mechanisms, drug efficacy and side effects. These considerations often demand the concomitant development of monitoring systems with sufficient temporal and spatial resolution. Methodology and Results: This study attempts to configure and optimize a clinical 3 Tesla magnetic resonance scanner to facilitate imaging of small animal central nervous system pathologies. The hardware of the scanner was complemented by a custom-built, 4-channel phased array coil system. Extensive modification of standard sequence protocols was carried out based on tissue relaxometric calculations. Proton density differences between the gray and white matter of the rodent spinal cord along with transverse relaxation due to magnetic susceptibility differences at the cortex and striatum of both rats and mice demonstrated statistically significant differences. The employed parallel imaging reconstruction algorithms had distinct properties dependent on the sequence type and in the presence of the contrast agent. The attempt to morphologically phenotype a normal healthy rat brain in multiple planes delineated a number of anatomical regions, and all the clinically relevant sequels following acute cerebral ischemia could be adequately characterized. Changes in blood-brain-barrier permeability following ischemia-reperfusion were also apparent at a later time. Typical characteristics of intracerebral haemorrhage at acute and chronic stages were also visualized up to one month. Two models of rodent spinal cord injury were adequately characterized and closely mimicked the results of histological studies. In the employed rodent animal handling system a mouse model of glioblastoma was also studied with unequivocal results. Conclusions: The implemented customizations including extensive sequence protocol modifications resulted in images of high diagnostic quality. These results prove that lack of dedicated animal scanners shouldn't discourage conventional small animal imaging studies.}, language = {en} } @article{EndesfelderMalkuschFlottmannetal.2011, author = {Endesfelder, Ulrike and Malkusch, Sebastian and Flottmann, Benjamin and Mondry, Justine and Liguzinski, Piotr and Verveer, Peter J. and Heilemann, Mike}, title = {Chemically Induced Photoswitching of Fluorescent Probes - A General Concept for Super-Resolution Microscopy}, series = {Molecules}, volume = {16}, journal = {Molecules}, number = {4}, doi = {10.3390/molecules16043106}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134080}, pages = {3106-3118}, year = {2011}, abstract = {We review fluorescent probes that can be photoswitched or photoactivated and are suited for single-molecule localization based super-resolution microscopy. We exploit the underlying photochemical mechanisms that allow photoswitching of many synthetic organic fluorophores in the presence of reducing agents, and study the impact of these on the photoswitching properties of various photoactivatable or photoconvertible fluorescent proteins. We have identified mEos2 as a fluorescent protein that exhibits reversible photoswitching under various imaging buffer conditions and present strategies to characterize reversible photoswitching. Finally, we discuss opportunities to combine fluorescent proteins with organic fluorophores for dual-color photoswitching microscopy.}, language = {en} } @article{OndruschKreft2011, author = {Ondrusch, Nicolai and Kreft, J{\"u}rgen}, title = {Blue and Red Light Modulates SigB-Dependent Gene Transcription, Swimming Motility and Invasiveness in \(Listeria\) \(monocytogenes\)}, series = {PLoS ONE}, volume = {6}, journal = {PLoS ONE}, number = {1}, doi = {10.1371/journal.pone.0016151}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-134050}, pages = {e16151}, year = {2011}, abstract = {Background: In a number of gram-positive bacteria, including Listeria, the general stress response is regulated by the alternative sigma factor B (SigB). Common stressors which lead to the activation of SigB and the SigB-dependent regulon are high osmolarity, acid and several more. Recently is has been shown that also blue and red light activates SigB in Bacillus subtilis. Methodology/Principal Findings: By qRT-PCR we analyzed the transcriptional response of the pathogen L. monocytogenes to blue and red light in wild type bacteria and in isogenic deletion mutants for the putative blue-light receptor Lmo0799 and the stress sigma factor SigB. It was found that both blue (455 nm) and red (625 nm) light induced the transcription of sigB and SigB-dependent genes, this induction was completely abolished in the SigB mutant. The blue-light effect was largely dependent on Lmo0799, proving that this protein is a genuine blue-light receptor. The deletion of lmo0799 enhanced the red-light effect, the underlying mechanism as well as that of SigB activation by red light remains unknown. Blue light led to an increased transcription of the internalin A/B genes and of bacterial invasiveness for Caco-2 enterocytes. Exposure to blue light also strongly inhibited swimming motility of the bacteria in a Lmo0799- and SigB-dependent manner, red light had no effect there. Conclusions/Significance: Our data established that visible, in particular blue light is an important environmental signal with an impact on gene expression and physiology of the non-phototrophic bacterium L. monocytogenes. In natural environments these effects will result in sometimes random but potentially also cyclic fluctuations of gene activity, depending on the light conditions prevailing in the respective habitat.}, language = {en} } @article{SchmittKellerNourkamiTutdibietal.2011, author = {Schmitt, Jana and Keller, Andreas and Nourkami-Tutdibi, Nasenien and Heisel, Sabrina and Habel, Nunja and Leidinger, Petra and Ludwig, Nicole and Gessler, Manfred and Graf, Norbert and Berthold, Frank and Lenhof, Hans-Peter and Meese, Eckart}, title = {Autoantibody Signature Differentiates Wilms Tumor Patients from Neuroblastoma Patients}, series = {PLoS ONE}, volume = {6}, journal = {PLoS ONE}, number = {12}, doi = {10.1371/journal.pone.0028951}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-133794}, pages = {e28951}, year = {2011}, abstract = {Several studies report autoantibody signatures in cancer. The majority of these studies analyzed adult tumors and compared the seroreactivity pattern of tumor patients with the pattern in healthy controls. Here, we compared the autoimmune response in patients with neuroblastoma and patients with Wilms tumor representing two different childhood tumors. We were able to differentiate untreated neuroblastoma patients from untreated Wilms tumor patients with an accuracy of 86.8\%, a sensitivity of 87.0\% and a specificity of 86.7\%. The separation of treated neuroblastoma patients from treated Wilms tumor patients' yielded comparable results with an accuracy of 83.8\%. We furthermore identified the antigens that contribute most to the differentiation between both tumor types. The analysis of these antigens revealed that neuroblastoma was considerably more immunogenic than Wilms tumor. The reported antigens have not been found to be relevant for comparative analyses between other tumors and controls. In summary, neuroblastoma appears as a highly immunogenic tumor as demonstrated by the extended number of antigens that separate this tumor from Wilms tumor.}, language = {en} } @article{EckhardtAndersMuranyietal.2011, author = {Eckhardt, Manon and Anders, Maria and Muranyi, Walter and Heilemann, Mike and Krijnse-Locker, Jacomine and M{\"u}ller, Barbara}, title = {A SNAP-Tagged Derivative of HIV-1-A Versatile Tool to Study Virus-Cell Interactions}, series = {PLoS ONE}, volume = {6}, journal = {PLoS ONE}, number = {7}, doi = {10.1371/journal.pone.0022007}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-133534}, pages = {e22007}, year = {2011}, abstract = {Fluorescently labeled human immunodeficiency virus (HIV) derivatives, combined with the use of advanced fluorescence microscopy techniques, allow the direct visualization of dynamic events and individual steps in the viral life cycle. HIV proteins tagged with fluorescent proteins (FPs) have been successfully used for live-cell imaging analyses of HIV-cell interactions. However, FPs display limitations with respect to their physicochemical properties, and their maturation kinetics. Furthermore, several independent FP-tagged constructs have to be cloned and characterized in order to obtain spectral variations suitable for multi-color imaging setups. In contrast, the so-called SNAP-tag represents a genetically encoded non-fluorescent tag which mediates specific covalent coupling to fluorescent substrate molecules in a self-labeling reaction. Fusion of the SNAP-tag to the protein of interest allows specific labeling of the fusion protein with a variety of synthetic dyes, thereby offering enhanced flexibility for fluorescence imaging approaches. Here we describe the construction and characterization of the HIV derivative HIV(SNAP), which carries the SNAP-tag as an additional domain within the viral structural polyprotein Gag. Introduction of the tag close to the C-terminus of the matrix domain of Gag did not interfere with particle assembly, release or proteolytic virus maturation. The modified virions were infectious and could be propagated in tissue culture, albeit with reduced replication capacity. Insertion of the SNAP domain within Gag allowed specific staining of the viral polyprotein in the context of virus producing cells using a SNAP reactive dye as well as the visualization of individual virions and viral budding sites by stochastic optical reconstruction microscopy. Thus, HIV(SNAP) represents a versatile tool which expands the possibilities for the analysis of HIV-cell interactions using live cell imaging and sub-diffraction fluorescence microscopy.}, language = {en} } @article{MatosSucenaMachadoetal.2011, author = {Matos, Isa and Sucena, {\`E}lio and Machado, Miguel P and Gardner, Rui and In{\´a}cio, {\^A}ngela and Schartl, Manfred and Coelho, Maria M}, title = {Ploidy mosaicism and allele-specific gene expression differences in the allopolyploid \(Squalius\) \(alburnoides\)}, series = {BMC Genetics}, volume = {12}, journal = {BMC Genetics}, number = {101}, doi = {10.1186/1471-2156-12-101}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142879}, pages = {1-10}, year = {2011}, abstract = {Background Squalius alburnoides is an Iberian cyprinid fish resulting from an interspecific hybridisation between Squalius pyrenaicus females (P genome) and males of an unknown Anaecypris hispanica- like species (A genome). S. alburnoides is an allopolyploid hybridogenetic complex, which makes it a likely candidate for ploidy mosaicism occurrence, and is also an interesting model to address questions about gene expression regulation and genomic interactions. Indeed, it was previously suggested that in S. alburnoides triploids (PAA composition) silencing of one of the three alleles (mainly of the P allele) occurs. However, not a whole haplome is inactivated but a more or less random inactivation of alleles varying between individuals and even between organs of the same fish was seen. In this work we intended to correlate expression differences between individuals and/or between organs to the occurrence of mosaicism, evaluating if mosaics could explain previous observations and its impact on the assessment of gene expression patterns. Results To achieve our goal, we developed flow cytometry and cell sorting protocols for this system generating more homogenous cellular and transcriptional samples. With this set-up we detected 10\% ploidy mosaicism within the S. alburnoides complex, and determined the allelic expression profiles of ubiquitously expressed genes (rpl8; gapdh and β-actin) in cells from liver and kidney of mosaic and non-mosaic individuals coming from different rivers over a wide geographic range. Conclusions Ploidy mosaicism occurs sporadically within the S. alburnoides complex, but in a frequency significantly higher than reported for other organisms. Moreover, we could exclude the influence of this phenomenon on the detection of variable allelic expression profiles of ubiquitously expressed genes (rpl8; gapdh and β-actin) in cells from liver and kidney of triploid individuals. Finally, we determined that the expression patterns previously detected only in a narrow geographic range is not a local restricted phenomenon but is pervasive in rivers where S. pyrenaicus is sympatric with S. alburnoides. We discuss mechanisms that could lead to the formation of mosaic S. alburnoides and hypothesise about a relaxation of the mechanisms that impose a tight control over mitosis and ploidy control in mixoploids."}, language = {en} } @article{SchwedeJonesEngstleretal.2011, author = {Schwede, Angela and Jones, Nicola and Engstler, Markus and Carrington, Mark}, title = {The VSG C-terminal domain is inaccessible to antibodies on live trypanosomes}, series = {Molecular \& Biochemical Parasitology}, volume = {175}, journal = {Molecular \& Biochemical Parasitology}, number = {2}, doi = {10.1016/j.molbiopara.2010.11.004}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142746}, pages = {201-204}, year = {2011}, abstract = {In the mammalian host, the Trypanosoma brucei cell surface is covered with a densely packed protein coat of a single protein, the variant surface glycoprotein (VSG). The VSG is believed to shield invariant surface proteins from host antibodies but there is limited information on how far antibodies can penetrate into the VSG monolayer. Here, the VSG surface coat was probed to determine whether it acts as a barrier to binding of antibodies to the membrane proximal VSG C-terminal domain. The binding of C-terminal domain antibodies to VSG221 or VSG118 was compared with antibodies recognising the cognate whole VSGs. The C-terminal VSG domain was inaccessible to antibodies on live cells but not on fixed cells. This provides further evidence that the VSG coat acts as a barrier and protects the cell from antibodies that would otherwise bind to some of the other externally disposed proteins.}, language = {en} } @article{ThormannRaupachWagneretal.2011, author = {Thormann, Birthe and Raupach, Michael J. and Wagner, Thomas and W{\"a}gele, Johann W. and Peters, Marcell K.}, title = {Testing a Short Nuclear Marker for Inferring Staphylinid Beetle Diversity in an African Tropical Rain Forest}, series = {PLoS ONE}, volume = {6}, journal = {PLoS ONE}, number = {3}, doi = {10.1371/journal.pone.0018101}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-142666}, pages = {e18101}, year = {2011}, abstract = {Background: The use of DNA based methods for assessing biodiversity has become increasingly common during the last years. Especially in speciose biomes as tropical rain forests and/or in hyperdiverse or understudied taxa they may efficiently complement morphological approaches. The most successful molecular approach in this field is DNA barcoding based on cytochrome c oxidase I (COI) marker, but other markers are used as well. Whereas most studies aim at identifying or describing species, there are only few attempts to use DNA markers for inventorying all animal species found in environmental samples to describe variations of biodiversity patterns. Methodology/Principal Findings: In this study, an analysis of the nuclear D3 region of the 28S rRNA gene to delimit species-like units is compared to results based on distinction of morphospecies. Data derived from both approaches are used to assess diversity and composition of staphylinid beetle communities of a Guineo-Congolian rain forest in Kenya. Beetles were collected with a standardized sampling design across six transects in primary and secondary forests using pitfall traps. Sequences could be obtained of 99\% of all individuals. In total, 76 molecular operational taxonomic units (MOTUs) were found in contrast to 70 discernible morphospecies. Despite this difference both approaches revealed highly similar biodiversity patterns, with species richness being equal in primary and secondary forests, but with divergent species communities in different habitats. The D3-MOTU approach proved to be an efficient tool for biodiversity analyses. Conclusions/Significance: Our data illustrate that the use of MOTUs as a proxy for species can provide an alternative to morphospecies identification for the analysis of changes in community structure of hyperdiverse insect taxa. The efficient amplification of the D3-marker and the ability of the D3-MOTUs to reveal similar biodiversity patterns as analyses of morphospecies recommend its use in future molecular studies on biodiversity.}, language = {en} } @article{CruseWehner2011, author = {Cruse, Holk and Wehner, R{\"u}diger}, title = {No Need for a Cognitive Map: Decentralized Memory for Insect Navigation}, series = {PLoS computational biology}, volume = {7}, journal = {PLoS computational biology}, number = {3}, doi = {10.1371/journal.pcbi.1002009}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-141184}, pages = {e1002009}, year = {2011}, abstract = {In many animals the ability to navigate over long distances is an important prerequisite for foraging. For example, it is widely accepted that desert ants and honey bees, but also mammals, use path integration for finding the way back to their home site. It is however a matter of a long standing debate whether animals in addition are able to acquire and use so called cognitive maps. Such a 'map', a global spatial representation of the foraging area, is generally assumed to allow the animal to find shortcuts between two sites although the direct connection has never been travelled before. Using the artificial neural network approach, here we develop an artificial memory system which is based on path integration and various landmark guidance mechanisms ( a bank of individual and independent landmark-defined memory elements). Activation of the individual memory elements depends on a separate motivation network and an, in part, asymmetrical lateral inhibition network. The information concerning the absolute position of the agent is present, but resides in a separate memory that can only be used by the path integration subsystem to control the behaviour, but cannot be used for computational purposes with other memory elements of the system. Thus, in this simulation there is no neural basis of a cognitive map. Nevertheless, an agent controlled by this network is able to accomplish various navigational tasks known from ants and bees and often discussed as being dependent on a cognitive map. For example, map-like behaviour as observed in honey bees arises as an emergent property from a decentralized system. This behaviour thus can be explained without referring to the assumption that a cognitive map, a coherent representation of foraging space, must exist. We hypothesize that the proposed network essentially resides in the mushroom bodies of the insect brain.}, language = {en} } @article{BuchheimKellerKoetschanetal.2011, author = {Buchheim, Mark A. and Keller, Alexander and Koetschan, Christian and F{\"o}rster, Frank and Merget, Benjamin and Wolf, Matthias}, title = {Internal Transcribed Spacer 2 (nu ITS2 rRNA) Sequence-Structure Phylogenetics: Towards an Automated Reconstruction of the Green Algal Tree of Life}, series = {PLoS ONE}, volume = {6}, journal = {PLoS ONE}, number = {2}, doi = {10.1371/journal.pone.0016931}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-140866}, pages = {e16931}, year = {2011}, abstract = {Background: Chloroplast-encoded genes (matK and rbcL) have been formally proposed for use in DNA barcoding efforts targeting embryophytes. Extending such a protocol to chlorophytan green algae, though, is fraught with problems including non homology (matK) and heterogeneity that prevents the creation of a universal PCR toolkit (rbcL). Some have advocated the use of the nuclear-encoded, internal transcribed spacer two (ITS2) as an alternative to the traditional chloroplast markers. However, the ITS2 is broadly perceived to be insufficiently conserved or to be confounded by introgression or biparental inheritance patterns, precluding its broad use in phylogenetic reconstruction or as a DNA barcode. A growing body of evidence has shown that simultaneous analysis of nucleotide data with secondary structure information can overcome at least some of the limitations of ITS2. The goal of this investigation was to assess the feasibility of an automated, sequence-structure approach for analysis of IT2 data from a large sampling of phylum Chlorophyta. Methodology/Principal Findings: Sequences and secondary structures from 591 chlorophycean, 741 trebouxiophycean and 938 ulvophycean algae, all obtained from the ITS2 Database, were aligned using a sequence structure-specific scoring matrix. Phylogenetic relationships were reconstructed by Profile Neighbor-Joining coupled with a sequence structure-specific, general time reversible substitution model. Results from analyses of the ITS2 data were robust at multiple nodes and showed considerable congruence with results from published phylogenetic analyses. Conclusions/Significance: Our observations on the power of automated, sequence-structure analyses of ITS2 to reconstruct phylum-level phylogenies of the green algae validate this approach to assessing diversity for large sets of chlorophytan taxa. Moreover, our results indicate that objections to the use of ITS2 for DNA barcoding should be weighed against the utility of an automated, data analysis approach with demonstrated power to reconstruct evolutionary patterns for highly divergent lineages.}, language = {en} } @article{UppaluriNaglerStellamannsetal.2011, author = {Uppaluri, Sravanti and Nagler, Jan and Stellamanns, Eric and Heddergott, Niko and Herminghaus, Stephan and Pfohl, Thomas and Engstler, Markus}, title = {Impact of Microscopic Motility on the Swimming Behavior of Parasites: Straighter Trypanosomes are More Directional}, series = {PLoS Computational Biology}, volume = {7}, journal = {PLoS Computational Biology}, number = {6}, doi = {10.1371/journal.pcbi.1002058}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-140814}, pages = {e1002058}, year = {2011}, abstract = {Microorganisms, particularly parasites, have developed sophisticated swimming mechanisms to cope with a varied range of environments. African Trypanosomes, causative agents of fatal illness in humans and animals, use an insect vector (the Tsetse fly) to infect mammals, involving many developmental changes in which cell motility is of prime importance. Our studies reveal that differences in cell body shape are correlated with a diverse range of cell behaviors contributing to the directional motion of the cell. Straighter cells swim more directionally while cells that exhibit little net displacement appear to be more bent. Initiation of cell division, beginning with the emergence of a second flagellum at the base, correlates to directional persistence. Cell trajectory and rapid body fluctuation correlation analysis uncovers two characteristic relaxation times: a short relaxation time due to strong body distortions in the range of 20 to 80 ms and a longer time associated with the persistence in average swimming direction in the order of 15 seconds. Different motility modes, possibly resulting from varying body stiffness, could be of consequence for host invasion during distinct infective stages.}, language = {en} } @article{NiewaldaVoellerEschbachetal.2011, author = {Niewalda, Thomas and V{\"o}ller, Thomas and Eschbach, Claire and Ehmer, Julia and Wen-Chuang, Chou and Timme, Marc and Fiala, Andr{\´e} and Gerber, Bertram}, title = {A Combined Perceptual, Physico-Chemical, and Imaging Approach to 'Odour-Distances' Suggests a Categorizing Function of the Drosophila Antennal Lobe}, series = {PLoS One}, volume = {6}, journal = {PLoS One}, number = {9}, doi = {10.1371/journal.pone.0024300}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-133510}, pages = {e24300}, year = {2011}, abstract = {How do physico-chemical stimulus features, perception, and physiology relate? Given the multi-layered and parallel architecture of brains, the question specifically is where physiological activity patterns correspond to stimulus features and/or perception. Perceived distances between six odour pairs are defined behaviourally from four independent odour recognition tasks. We find that, in register with the physico-chemical distances of these odours, perceived distances for 3octanol and n-amylacetate are consistently smallest in all four tasks, while the other five odour pairs are about equally distinct. Optical imaging in the antennal lobe, using a calcium sensor transgenically expressed in only first-order sensory or only second-order olfactory projection neurons, reveals that 3-octanol and n-amylacetate are distinctly represented in sensory neurons, but appear merged in projection neurons. These results may suggest that within-antennal lobe processing funnels sensory signals into behaviourally meaningful categories, in register with the physico-chemical relatedness of the odours.}, language = {en} } @article{BijuSchwarzLinkeetal.2011, author = {Biju, Joseph and Schwarz, Roland and Linke, Burkhard and Blom, Jochen and Becker, Anke and Claus, Heike and Goesmann, Alexander and Frosch, Matthias and M{\"u}ller, Tobias and Vogel, Ulrich and Schoen, Christoph}, title = {Virulence Evolution of the Human Pathogen Neisseria meningitidis by Recombination in the Core and Accessory Genome}, series = {PLoS One}, volume = {6}, journal = {PLoS One}, number = {4}, doi = {10.1371/journal.pone.0018441}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-137960}, pages = {e18441}, year = {2011}, abstract = {Background Neisseria meningitidis is a naturally transformable, facultative pathogen colonizing the human nasopharynx. Here, we analyze on a genome-wide level the impact of recombination on gene-complement diversity and virulence evolution in N. meningitidis. We combined comparative genome hybridization using microarrays (mCGH) and multilocus sequence typing (MLST) of 29 meningococcal isolates with computational comparison of a subset of seven meningococcal genome sequences. Principal Findings We found that lateral gene transfer of minimal mobile elements as well as prophages are major forces shaping meningococcal population structure. Extensive gene content comparison revealed novel associations of virulence with genetic elements besides the recently discovered meningococcal disease associated (MDA) island. In particular, we identified an association of virulence with a recently described canonical genomic island termed IHT-E and a differential distribution of genes encoding RTX toxin- and two-partner secretion systems among hyperinvasive and non-hyperinvasive lineages. By computationally screening also the core genome for signs of recombination, we provided evidence that about 40\% of the meningococcal core genes are affected by recombination primarily within metabolic genes as well as genes involved in DNA replication and repair. By comparison with the results of previous mCGH studies, our data indicated that genetic structuring as revealed by mCGH is stable over time and highly similar for isolates from different geographic origins. Conclusions Recombination comprising lateral transfer of entire genes as well as homologous intragenic recombination has a profound impact on meningococcal population structure and genome composition. Our data support the hypothesis that meningococcal virulence is polygenic in nature and that differences in metabolism might contribute to virulence.}, language = {en} } @article{ParthoChenBrauckhoffetal.2011, author = {Partho, Halder and Chen, Yi-chun and Brauckhoff, Janine and Hofbauer, Alois and Dabauvalle, Marie-Christine and Lewandrowski, Urs and Winkler, Christiane and Sickmann, Albert and Buchner, Erich}, title = {Identification of Eps15 as Antigen Recognized by the Monoclonal Antibodies aa2 and ab52 of the Wuerzburg Hybridoma Library against Drosophila Brain}, series = {PLoS One}, volume = {6}, journal = {PLoS One}, number = {12}, doi = {10.1371/journal.pone.0029352}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-137957}, pages = {e29352}, year = {2011}, abstract = {The Wuerzburg Hybridoma Library against the Drosophila brain represents a collection of around 200 monoclonal antibodies that bind to specific structures in the Drosophila brain. Here we describe the immunohistochemical staining patterns, the Western blot signals of one- and two-dimensional electrophoretic separation, and the mass spectrometric characterization of the target protein candidates recognized by the monoclonal antibodies aa2 and ab52 from the library. Analysis of a mutant of a candidate gene identified the Drosophila homolog of the Epidermal growth factor receptor Pathway Substrate clone 15 (Eps15) as the antigen for these two antibodies.}, language = {en} } @article{HendriksmaHaertelSteffanDewenter2011, author = {Hendriksma, Harmen P. and H{\"a}rtel, Stephan and Steffan-Dewenter, Ingolf}, title = {Testing Pollen of Single and Stacked Insect-Resistant Bt-Maize on In vitro Reared Honey Bee Larvae}, series = {PLoS One}, volume = {6}, journal = {PLoS One}, number = {12}, doi = {10.1371/journal.pone.0028174}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-137803}, pages = {e28174}, year = {2011}, abstract = {The ecologically and economic important honey bee (Apis mellifera) is a key non-target arthropod species in environmental risk assessment (ERA) of genetically modified (GM) crops. Honey bee larvae are directly exposed to transgenic products by the consumption of GM pollen. But most ERA studies only consider responses of adult bees, although Bt-proteins primarily affect the larval phases of target organisms. We adopted an in vitro larvae rearing system, to assess lethal and sublethal effects of Bt-pollen consumption in a standardized eco-toxicological bioassay. The effects of pollen from two Bt-maize cultivars, one expressing a single and the other a total of three Bt-proteins, on the survival and prepupae weight of honey bee larvae were analyzed. The control treatments included pollen from three non-transgenic maize varieties and of Heliconia rostrata. Three days old larvae were fed the realistic exposure dose of 2 mg pollen within the semi-artificial diet. The larvae were monitored over 120 h, until the prepupal stage, where larvae terminate feeding and growing. Neither single nor stacked Bt-maize pollen showed an adverse effect on larval survival and the prepupal weight. In contrast, feeding of H. rostrata pollen caused significant toxic effects. The results of this study indicate that pollen of the tested Bt-varieties does not harm the development of in vitro reared A. mellifera larvae. To sustain the ecosystem service of pollination, Bt-impact on A. mellifera should always be a crucial part of regulatory biosafety assessments. We suggest that our approach of feeding GM pollen on in vitro reared honey bee larvae is well suited of becoming a standard bioassay in regulatory risk assessments schemes of GM crops.}, language = {en} } @article{KatjaLopezTillichetal.2011, author = {Katja, Schulze and L{\´o}pez, Diana A. and Tillich, Ulrich M. and Frohme, Marcus}, title = {A simple viability analysis for unicellular cyanobacteria using a new autofluorescence assay, automated microscopy, and ImageJ}, series = {BMC Biotechnology}, volume = {11}, journal = {BMC Biotechnology}, number = {118}, doi = {10.1186/1472-6750-11-118}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-137735}, year = {2011}, abstract = {Background Currently established methods to identify viable and non-viable cells of cyanobacteria are either time-consuming (eg. plating) or preparation-intensive (eg. fluorescent staining). In this paper we present a new and fast viability assay for unicellular cyanobacteria, which uses red chlorophyll fluorescence and an unspecific green autofluorescence for the differentiation of viable and non-viable cells without the need of sample preparation. Results The viability assay for unicellular cyanobacteria using red and green autofluorescence was established and validated for the model organism Synechocystis sp. PCC 6803. Both autofluorescence signals could be observed simultaneously allowing a direct classification of viable and non-viable cells. The results were confirmed by plating/colony count, absorption spectra and chlorophyll measurements. The use of an automated fluorescence microscope and a novel ImageJ based image analysis plugin allow a semi-automated analysis. Conclusions The new method simplifies the process of viability analysis and allows a quick and accurate analysis. Furthermore results indicate that a combination of the new assay with absorption spectra or chlorophyll concentration measurements allows the estimation of the vitality of cells.}, language = {en} } @phdthesis{Stieb2011, author = {Stieb, Sara Mae}, title = {Synaptic plasticity in visual and olfactory brain centers of the desert ant Cataglyphis}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-85584}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {W{\"u}stenameisen der Gattung Cataglyphis wurden zu Modellsystemen bei der Erforschung der Navigationsmechanismen der Insekten. Ein altersabh{\"a}ngiger Polyethismus trennt deren Kolonien in Innendienst-Arbeiterinnen und kurzlebige lichtausgesetzte Fourageure. Nachdem die Ameisen in strukturlosem oder strukturiertem Gel{\"a}nde bis zu mehrere hundert Meter weite Distanzen zur{\"u}ckgelegt haben, k{\"o}nnen sie pr{\"a}zise zu ihrer oft unauff{\"a}lligen Nest{\"o}ffnung zur{\"u}ckzukehren. Um diese enorme Navigationsleistung zu vollbringen, bedienen sich die Ameisen der sogenannten Pfadintegration, welche die Informationen aus einem Polarisationskompass und einem Entfernungsmesser verrechnet; des Weiteren orientieren sie sich an Landmarken und nutzen olfaktorische Signale. Im Fokus dieser Arbeit steht C. fortis, welche in Salzpfannen des westlichen Nordafrikas endemisch ist - einem Gebiet, welches vollst{\"a}ndig von anderen Cataglyphis Arten gemieden wird. Die Tatsache, dass Cataglyphis eine hohe Verhaltensflexibilit{\"a}t aufweist, welche mit sich drastisch {\"a}ndernden sensorischen Anforderungen verbunden ist, macht diese Ameisen zu besonders interessanten Studienobjekten bei der Erforschung synaptischer Plastizit{\"a}t visueller und olfaktorischer Gehirnzentren. Diese Arbeit fokussiert auf plastische {\"A}nderungen in den Pilzk{\"o}rpern (PK) - sensorischen Integrationszentren, die mutmaßlich an Lern- und Erinnerungsprozessen, und auch vermutlich am Prozess des Landmarkenlernens beteiligt sind - und auf plastische {\"A}nderungen in den synaptischen Komplexen des Lateralen Akzessorischen Lobus (LAL) - einer bekannten Relaisstation in der Polarisations-Leitungsbahn. Um die strukturelle synaptische Plastizit{\"a}t der PK in C. fortis zu quantifizieren, wurden mithilfe immunozytochemischer F{\"a}rbungen die pr{\"a}- und postsynaptischen Profile klar ausgepr{\"a}gter synaptischer Komplexe (Mikroglomeruli, MG) der visuellen Region (Kragen) und der olfaktorischen Region (Lippe) der PK-Kelche visualisiert. Die Ergebnisse legen dar, dass eine Volumenzunahme der PK-Kelche w{\"a}hrend des {\"U}bergangs von Innendiensttieren zu Fourageuren von einer Abnahme der MG-Anzahl im Kragen und, mit einem geringeren Anteil, in der Lippe - dieser Effekt wird als Pruning bezeichnet - und einem gleichzeitigen Auswachsen an Dendriten PK-intrinsischer Kenyonzellen begleitet wird. Im Dunkeln gehaltene Tiere unterschiedlichen Alters zeigen nach Lichtaussetzung den gleichen Effekt und im Dunkel gehaltene, den Fourageuren altersm{\"a}ßig angepasste Tiere weisen eine vergleichbare MG-Anzahl im Kragen auf wie Innendiensttiere. Diese Ergebnisse deuten darauf hin, dass die immense strukturelle synaptische Plastizit{\"a}t in der Kragenregion der PK-Kelche haupts{\"a}chlich durch visuelle Erfahrungen ausgel{\"o}st wird und nicht ausschließlich mit Hilfe eines internen Programms abgespielt wird. Ameisen, welche unter Laborbedingungen bis zu einem Jahr alt wurden, zeigen eine vergleichbare Plastizit{\"a}t. Dies deutet darauf hin, dass das System {\"u}ber die ganze Lebensspanne eines Individuums flexibel bleibt. Erfahrene Fourageure wurden in Dunkelheit zur{\"u}ckgef{\"u}hrt, um zu untersuchen, ob die lichtausgel{\"o}ste synaptische Umstrukturierung reversibel ist, doch ihre PK zeigen nur einige die Zur{\"u}ckf{\"u}hrung widerspiegelnde Plastizit{\"a}tsauspr{\"a}gungen, besonders eine {\"A}nderung der pr{\"a}synaptischen Synapsinexprimierung. Mithilfe immunozytochemischer F{\"a}rbungen, konfokaler Mikroskopie und 3D-Rekonstruktionen wurden die pr{\"a}- und postsynaptischen Strukturen synaptischer Komplexe des LAL in C. fortis analysiert und potentielle strukturelle {\"A}nderungen bei Innendiensttieren und Fourageuren quantifiziert. Die Ergebnisse zeigen, dass diese Komplexe aus postsynaptischen, in einer zentralen Region angeordneten Forts{\"a}tzen bestehen, welche umringt sind von einem pr{\"a}synaptischen kelchartigen Profil. Eingehende und ausgehende Trakte wurden durch Farbstoffinjektionen identifiziert: Projektionsneurone des Anterioren Optischen Tuberkels kontaktieren Neurone, welche in den Zentralkomplex ziehen. Der Verhaltens{\"u}bergang wird von einer Zunahme an synaptischen Komplexen um ~13\% begleitet. Dieser Zuwachs suggeriert eine Art Kalibrierungsprozess in diesen potentiell kr{\"a}ftigen synaptischen Kontakten, welche vermutlich eine schnelle und belastbare Signal{\"u}bertragung in der Polarisationsbahn liefern. Die Analyse von im Freiland aufgenommener Verhaltenweisen von C. fortis enth{\"u}llen, dass die Ameisen, bevor sie mit ihrer Fouragiert{\"a}tigkeit anfangen, bis zu zwei Tage lang in unmittelbarer N{\"a}he des Nestes Entdeckungsl{\"a}ufe unternehmen, welche Pirouetten {\"a}hnliche Drehungen beinhalten. W{\"a}hrend dieser Entdeckungsl{\"a}ufe sammeln die Ameisen Lichterfahrung und assoziieren m{\"o}glicherweise den Nesteingang mit spezifischen Landmarken oder werden anderen visuellen Informationen, wie denen des Polarisationsmusters, ausgesetzt und adaptieren begleitend ihre neuronalen Netzwerke an die bevorstehende Herausforderung. Dar{\"u}ber hinaus k{\"o}nnten die Pirouetten einer Stimulation der an der Polarisationsbahn beteiligten neuronalen Netzwerke dienen. Videoanalysen legen dar, dass Lichtaussetzung nach drei Tagen die Bewegungsaktivit{\"a}t der Ameisen heraufsetzt. Die Tatsache, dass die neuronale Umstrukturierung in visuellen Zentren wie auch die Ver{\"a}nderungen im Verhalten im selben Zeitrahmen ablaufen, deutet darauf hin, dass ein Zusammenhang zwischen struktureller synaptischer Plastizit{\"a}t und dem Verhaltens{\"u}bergang von der Innendienst- zur Fouragierphase bestehen k{\"o}nnte. Cataglyphis besitzen hervorragende visuelle Navigationsf{\"a}higkeiten, doch sie nutzen zudem olfaktorische Signale, um das Nest oder die Futterquelle aufzusp{\"u}ren. Mithilfe konfokaler Mikroskopie und 3D-Rekonstruktionen wurden potentielle Anpassungen der prim{\"a}ren olfaktorischen Gehirnzentren untersucht, indem die Anzahl, Gr{\"o}ße und r{\"a}umliche Anordnung olfaktorischer Glomeruli im Antennallobus von C. fortis, C. albicans, C. bicolor, C. rubra, und C. noda verglichen wurde. Arbeiterinnen aller Cataglyphis-Arten haben eine geringere Glomeruli-Anzahl im Vergleich zu denen der mehr olfaktorisch-orientierten Formica Arten - einer Gattung nah verwandt mit Cataglyphis - und denen schon bekannter olfaktorisch-orientierter Ameisenarten. C. fortis hat die geringste Anzahl an Glomeruli im Vergleich zu allen anderen Cataglyphis-Arten und besitzt einen vergr{\"o}ßerten Glomerulus, der nahe dem Eingang des Antennennerves lokalisiert ist. C. fortis M{\"a}nnchen besitzen eine signifikant geringere Glomeruli-Anzahl im Vergleich zu Arbeiterinnen und K{\"o}niginnen und haben einen hervorstechenden M{\"a}nnchen-spezifischen Makroglomerulus, welcher wahrscheinlich an der Pheromon-Kommunikation beteiligt ist. Die Verhaltensrelevanz des vergr{\"o}ßerten Glomerulus der Arbeiterinnen bleibt schwer fassbar. Die Tatsache, dass C. fortis Mikrohabitate bewohnt, welche von allen anderen Cataglyphis Arten gemieden werden, legt nahe, dass extreme {\"o}kologische Bedingungen nicht nur zu Anpassungen der visuellen F{\"a}higkeiten, sondern auch des olfaktorischen Systems gef{\"u}hrt haben. Die vorliegende Arbeit veranschaulicht, dass Cataglyphis ein exzellenter Kandidat ist bei der Erforschung neuronaler Mechanismen, welche Navigationsfunktionalit{\"a}ten zugrundeliegen, und bei der Erforschung neuronaler Plastizit{\"a}t, welche verkn{\"u}pft ist mit der lebenslangen Flexibilit{\"a}t eines individuellen Verhaltensrepertoires.}, subject = {Neuroethologie}, language = {en} } @phdthesis{Hendriksma2011, author = {Hendriksma, Harmen P.}, title = {Non-target effects of a multiple insect resistant Bt-maize on the honey bee (Apis mellifera L.)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-70304}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Neue methodische Entwicklungen zur Untersuchung der Ursachen des weltweit beobachteten Bienensterbens sind n{\"o}tig, um die lebenswichtige {\"O}kosystemdienstleistung der Best{\"a}ubung zu gew{\"a}hrleisten. Die {\"o}kologisch und wirtschaftlich bedeutsame Honigbiene (Apis mellifera) ist ein wichtiger Nichtziel-Organismus im Zulassungsverfahren f{\"u}r gentechnisch ver{\"a}nderte Pflanzen. Bisher sind vor allem Methoden zur Testung erwachsener Bienen unter Laborbedingungen verwendet worden, aber f{\"u}r eine Risikobewertung mit Hilfe von standardisierten Bienenkolonien oder in vitro gez{\"u}chteten Honigbienenlarven sind keine robusten Methoden oder standardisierte Protokolle vorhanden. In dieser Arbeit wurde eine Vielzahl an neuen methodischen Ans{\"a}tzen f{\"u}r die Biosicherheitsforschung entwickelt: eine Mortalit{\"a}ts-Falle (Kapitel II), ein "Full-Life-Cycle" Test (III), eine robuste in vitro Aufzucht-Methodik (IV), ein standardisierter in vitro Test f{\"u}r Bt-Pollen (V), eine gemischte Toxizit{\"a}tspr{\"u}fung f{\"u}r transgene Reinproteine (VI) und eine {\"U}berpr{\"u}fung der Darmmikroflora sowie der Pollenverdauungrate (VII). Die Ergebnisse dieser Studien zeigten keine nachteiligen Wirkungen von Bt-Maispollen oder Bt-Reinproteinen im "Worst-Case" Szenario auf Honigbienen. In Anbetracht der Datenlage ist eine Sch{\"a}digung der Honigbiene durch den getesteten Bt-Mais Mon89034xMon88017 unwahrscheinlich. Die Anwendung der Untersuchungsmethoden in zuk{\"u}nftigen Biosicherheitsstudien f{\"u}r transgene Pflanzen wird empfohlen.}, subject = {Biene}, language = {en} } @phdthesis{Subota2011, author = {Subota, Ines}, title = {Switches in trypanosome differentiation: ALBA proteins acting on post-transcriptional mRNA control}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-85707}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Trypanosoma brucei is a digenetic eukaryotic parasite that develops in different tissues of a mammalian host and a tsetse fly. It is responsible for sleeping sickness in sub-saharan Africa. The parasite cycle involves more than nine developmental stages that can be clearly distinguished by their general morphology, their metabolism and the relative positioning of their DNA-containing organelles. During their development, trypanosomes remain exclusively extracellular and encounter changing environments with different physico-chemical properties (nutritional availability, viscosity, temperature, etc.). It has been proposed that trypanosomes use their flagellum as a sensing organelle, in agreement with the established role of structurally-related cilia in metazoa and ciliates. Recognition of environmental triggers is presumed to be at the initiation of differentiation events, leading to the parasite stage that is the best suited to the new environment. These changes are achieved by the modification of gene expression programmes, mostly underlying post-transcriptional control of mRNA transcripts. We first demonstrate that the RNA-binding proteins ALBA3/4 are involved in specific differentiation processes during the parasite development in the fly. They are cytosolic and expressed throughout the parasite cycle with the exception of the stages found in the tsetse fly proventriculus, as shown by both immunofluorescence and live cell analysis upon endogenous tagging with YFP. Knock-down of both proteins in the developmental stage preceding these forms leads to striking modifications: cell elongation, cell cycle arrest and relocalization of the nucleus in a posterior position, all typical of processes acting in parasites found in the proventriculus region. When ALBA3 is over-expressed from an exogenous copy during infection, it interferes with the relocalization of the nucleus in proventricular parasites. This is not observed for ALBA4 over-expression that does not visibly impede differentiation. Both ALBA3/4 proteins react to starvation conditions by accumulating in cytoplasmic stress granules together with DHH1, a recognized RNA-binding protein. ALBA3/4 proteins also partially colocalize with granules formed by polyA+ RNA in these conditions. We propose that ALBA are involved in trypanosome differentiation processes where they control a subset of developmentally regulated transcripts. These processes involving ALBA3/4 are likely to result from the specific activation of sensing pathways. In the second part of the thesis, we identify novel flagellar proteins that could act in sensing mechanisms. Several protein candidates were selected from a proteomic analysis of intact flagella performed in the host laboratory. This work validates their flagellar localization with high success (85\% of the proteins examined) and defines multiple different patterns of protein distribution in the flagellum. Two proteins are analyzed during development, one of them showing down-regulation in proventricular stages. The functional analysis of one novel flagellar membrane protein reveals its rapid dynamics within the flagellum but does not yield a visible phenotype in culture. This is coherent with sensory function that might not be needed in stable culture conditions, but could be required in natural conditions during development. In conclusion, this work adds new pieces to the puzzle of identifying molecular switches involved in developmental mRNA control and environmental sensing in trypanosome stages in the tsetse fly.}, subject = {Trypanosoma brucei}, language = {en} } @phdthesis{Kroker2011, author = {Kroker, Katja}, title = {Establishment and validation of hippocampal LTP for characterization of memory enhancing drugs as potential treatment of Alzheimer's disease}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-85412}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Die Alzheimer'sche Erkrankung ist eine neurodegenerative Erkrankung des Gehirns. Um geeignete Medikamente f{\"u}r die Behandlung der Alzheimer'schen Erkrankung zu finden, werden experimentelle Modellsysteme zur Erforschung von Substanzkandidaten verwendet. Ein solches experimentelles System ist die hippocampale Langzeitpotenzierung (LTP), welche ein anerkanntes in vitro Modell f{\"u}r die Erforschung der zugrundeliegenden zellul{\"a}ren Prozesse der Ged{\"a}chtnisbildung ist. Die vorliegende Arbeit besch{\"a}ftigt sich mit der Etablierung und Validierung von LTP in hippocampalen Hirnschnitten der Ratte um ged{\"a}chtnissteigernde Substanzen zur potentiellen Behandlung der Alzheimer'schen Erkrankung zu charakterisieren. Dazu wurde zun{\"a}chst ein Messsystem zur parallelen Charakterisierung mehrerer Schnitte aufgebaut, das Messungen bis zu sieben Stunden erlaubt (Kapitel 2). Dann wurden unterschiedliche Protokolle etabliert um Fr{\"u}h- und Sp{\"a}tphasen-LTP zu generieren. Dabei w{\"u}rde Fr{\"u}hphasen-LTP konzeptionell eher mit dem Kurzzeitged{\"a}chtnis einhergehen, w{\"a}hrend Sp{\"a}tphasen-LTP dem Langzeitged{\"a}chtnis gleichkommen w{\"u}rde (Kapitel 3). Da in Alzheimer-Patienten haupts{\"a}chlich ein Defizit cholinerger und glutamaterger Neurone vorliegt, wurden die validierten LTP Formen benutzt, um solche Substanzen zu analysieren, die potentiell cholinerge und/oder glutamaterge neuronale Funktion erh{\"o}hen. Die Effekte zweier ausschließlich cholinerge Funktion erh{\"o}hender Substanzen wurden analysiert: Der α4β2 nicotinische Acetylcholin-Rezeptor Agonist TC-1827 (Kapitel 4) und der Acetylcholinesterase-Inhibitor Donepezil (Kapitel 5). Beide Substanzen erh{\"o}hten Fr{\"u}hphasen-LTP, aber hatten keinen Effekt auf Sp{\"a}tphasen-LTP. Desweiteren wurden zwei Substanzen getestet, die ausschließlich mit glutamaterger Funktion interferieren: Der metabotrope Glutamatrezeptor 5 positiv allosterische Modulator ADX-47273 (Kapitel 3) und der Phosphodiesterase (PDE) 9A-Inhibitor BAY 73-6691 (Kapitel 5). ADX-47273 erh{\"o}hte Sp{\"a}tphasen-LTP, aber hatte keinen Effekt auf Fr{\"u}hphasen-LTP, wohingegen BAY 73-6691 eine erh{\"o}hende Wirkung auf beide LTP Formen aufwies und sogar Fr{\"u}h- in Sp{\"a}tphasen-LTP umwandelte. Die gleichen Effekte, wie bei dem PDE9A-Inhibitor, konnten auch mit dem partiellen α7 nicotinische Acetylcholin-Rezeptor Agonisten SSR180711 (Kapitel 4) demonstriert werden. SSR180711 wirkt sowohl auf cholinerge, als auch auf glutamaterge neuronale Funktion. Dann wurde die F{\"a}higkeit der Substanzen {\"u}berpr{\"u}ft, durch l{\"o}sliche Aβ Oligomere verschlechtertes LTP zu verbessern (Kapitel 6). L{\"o}sliche Aβ Oligomere, auch als amyloid-β derived diffusible ligands (ADDLs) bezeichnet, werden zurzeit als eine mutmaßliche Ursache der Alzheimer'schen Erkrankung angesehen. In der vorliegenden Arbeit wurde gezeigt, dass ADDLs Fr{\"u}h- und Sp{\"a}tphasen-LTP in verschiedenem Ausmaß vermindern. Donepezil und TC-1827 konnten die durch ADDLs induzierten Defizite bei Fr{\"u}hphasen-LTP geringf{\"u}gig wiederherstellen, aber sie hatten keinen Einfluss auf das durch ADDLs verschlechterte Sp{\"a}tphasen-LTP. Im Gegensatz dazu, konnten sowohl SSR180711 als auch BAY 73-6691 ein durch ADDLs verschlechtertes Fr{\"u}h- und Sp{\"a}tphasen-LTP komplett wiederherstellen. ADX-47273 hatte keinen positiven Effekt auf Fr{\"u}hphasen-LTP, welches durch ADDLs verschlechtert worden war, konnte aber ein durch ADDLs verschlechtertes Sp{\"a}tphasen-LTP teilweise wiederherstellen. Somit wurde der vorherige Befund der Arbeit best{\"a}tigt: Substanzen, welche die glutamaterge Funktion verbessern, scheinen nicht nur wirksamer im Bezug auf LTP-Erh{\"o}hung zu sein als Substanzen die ausschließlich cholinerge Funktion erh{\"o}hen, sondern sie sind auch in der Lage, durch l{\"o}sliche Aβ Oligomere verursachte Defizite bei LTP zu verbessern. Aus einem pr{\"a}klinischen Blickwinkel und basierend auf den Ergebnissen der vorliegenden Arbeit weisen demnach Substanzen, die glutamaterge Funktionen verbessern, ein hohes therapeutisches Potential als alternative Ans{\"a}tze bez{\"u}glich kognitiver Defizite auf. M{\"o}glicherweise k{\"o}nnten sie sogar wirksamere Ans{\"a}tze f{\"u}r die symptomatische Behandlung der Alzheimer'schen Erkrankung darstellen, als derzeitige Behandlungen, die ausschließlich cholinerge Funktion verbessern.}, subject = {Alzheimerkrankheit}, language = {en} } @phdthesis{Schaefer2011, author = {Sch{\"a}fer, Ingo}, title = {Fremdgenexpression in humanen Mitochondrien}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-85202}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Bei einer Vielzahl neuromuskul{\"a}rer und neurodegenerativer Erkrankungen spielen Fehlfunktionen der Mitochondrien eine wichtige Rolle. Da die Proteine der Atmungsketten-komplexe sowohl durch die mitochondriale DNA als auch durch das Kerngenom codiert werden, k{\"o}nnen Mutationen in beiden Genomen die Ausl{\"o}ser dieser Erkrankungen darstellen. Ver{\"a}nderungen der mitochondrialen DNA lassen sich - im Gegensatz zum Kerngenom - bisher nicht korrigieren, weshalb bei einem großen Teil der Erkrankungen nur die Symptome und nicht die Ausl{\"o}ser behandelt werden k{\"o}nnen. Das grundlegende Problem stellt dabei der Transport der DNA in die Mitochondrien dar. Ziel dieser Arbeit war es, mit Hilfe von physikalischen Transfektionsmethoden exogene DNA in die Mitochondrien menschlicher Kulturzellen einzubringen. Dazu wurden unterschiedliche Vektoren hergestellt, die in Mitochondrien das an die Mitochondrien angepasste gr{\"u}n fluoreszierende mtEGFP exprimieren sollen. Die Expressionsf{\"a}higkeit und Prozessierung dieser Konstrukte konnte in in-vitro-Assays mit einem Mitochondrienextrakt nachgewiesen werden. Bei Transfektionsversuchen mit der Gene Gun gelang es erstmals, exogene Plasmid-DNA in die Mitochondrien menschlicher Zellen einzubringen. Das durch die transfizierten Vektoren exprimierte mtEGFP konnte am Fluoreszenzmikroskop eindeutig in den Mitochondrien der Zellen lokalisiert werden. Eine Transfektion mit Hilfe magnetischer Partikel erwies sich jedoch nicht als zielf{\"u}hrend, da die die Partikel eine Eigenfluoreszenz aufwiesen, die eine Detektion der mtEGFP-Expression verhinderten. Eine wichtige Voraussetzung f{\"u}r die Transfektion von Mitochondrien durch mechanische Methoden wie die Mikroinjektion ist die reversible Induktion von Megamitochondrien, da sie erst in diesem Zustand penetriert werden k{\"o}nnen. Durch eine Ans{\"a}uerung des Kulturmediums mit Natriumacetat bzw. Essigs{\"a}ure konnten Mitochondrien erzeugt werden, die beinahe die Gr{\"o}ße des Zellkerns aufwiesen und somit ideale Bedingungen f{\"u}r die Mikroinjektion darstellen. Bei den anschließenden Mikroinjektionsversuchen mit den hergestellten mitochondrialen Expressionsvektoren wurden wiederum Zellen mit eindeutig gr{\"u}n fluoreszierenden Mitochondrien gefunden. Zusammenfassend wurden im Rahmen dieser Arbeit erstmalig menschliche Mitochondrien mit exogener DNA transfiziert. Dies stellt einen grundlegenden Schritt f{\"u}r die Entwicklung neuer Therapieformen bei mitochondrialen Myopathien dar. Zuvor m{\"u}ssen die Transfektionsmethoden jedoch noch weiter optimiert werden, um eine h{\"o}here Transfektionseffizienz zu erreichen.}, subject = {Mitochondrium}, language = {de} } @phdthesis{Duechs2011, author = {D{\"u}chs, Matthias}, title = {Effects of Toll-like receptor agonists on the pathogenesis of atopic asthma in mice}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-66369}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {In the last decades, both the incidence and the severity of asthma have steadily increased. Furthermore, available therapies only treat the symptoms but do not cure the disease. Immune modulation induced by TLR agonists may be a promising novel approach to effectively treat asthma as it targets the underlying immunopathology directly rather than one mediator alone. The aim of this thesis was to investigate if the immunostimulatory properties of Toll-like receptor (TLR) agonists can be utilized to develop novel therapeutic intervention strategies for the treatment of asthma using murine models of allergic inflammation. For this purpose five different TLR agonists were tested in preclinical mouse models of acute and chronic asthma, both in preventive and therapeutic settings. Firstly, TLR-2, 3, 4, 7/8 and 9 agonists were delivered intratracheally at different doses before pulmonary allergen exposure in the asthma model of acute inflammation. TLR9 agonist CpG-containing oligodeoxynucleotides (CpG) > TLR7 agonist Resiquimod (R848) > TLR3 agonists poly(I:C) strongly reduced allergen induced airway eosinophilia and IL-4 levels in a dose-dependent manner. All TLR agonists increased neutrophil numbers, TLR4 agonist lipopolysaccharide (LPS) > TLR2 agonist lipoteichonic acid (LTA) > poly(I:C) > CpG > R848 and, with the exception of R848, the amount of pro-inflammatory cytokines in the airways. Suppressive effects were not dependent upon IFN-γ and IL-10 or associated with increased numbers of regulatory T cells in the airways. All TLR agonists, except LTA, similarly reduced airway eosinophilia and IL-4 levels when applied therapeutically after allergen challenge. These results show that the TLR agonists have different suppressive effects on TH2 responses in the airways which further depend on the dose and the experimental setup in which they were tested. Interestingly, all agonists induced airway neutrophilia, albeit to different degrees, raising the question if TLR ligands are safe for human use when applied directly into the lung. Different TLR agonists are also being developed for human use as adjuvants combined with allergen in specific immunotherapy. Recent clinical data suggest that this may be achieved by induction of allergen-specific TH1 responses. For this reason, the ability of different TLR agonists to induce allergen-specific TH1 and suppress allergen-specific TH2 responses in a preclinical setting was investigated in this thesis. Different doses of the TLR agonists were applied together with allergen, then mice were exposed to allergen aerosol. CpG > LPS >LTA dose-dependently strongly suppressed the development of airway eosinophilia with poly(I:C) and R848 having no effect. The decrease in eosinophilic numbers was associated withincreased neutrophils present in the airways. IL-4 and IL-5 levels in the bronchoalveolar lavage fluid were also decreased when poly(I:C), LPS, and CpG were used. All TLR agonists increased allergen-specific IgG2a, and with the exception of poly(I:C), reduced allergen-specific IgE levels in the serum. Cutaneous anaphylaxis to allergen was completely prevented when LPS or CpG were given as adjuvant. The strongest TH1 responses were induced by CpG and poly(I:C), characterized by the presence of IFN-γ in the bronchoalveolar lavage and the highest allergen-specific IgG2a levels in the serum. This data supports approaches to use TLR9 or TLR4 agonists for human therapy as adjuvant in combination with allergen in novel specific immunotherapy formulations. In the last part of the thesis, it was investigated if TLR activation can also affect the pathology of severe chronic asthma. Therapeutic administration of R848 or CpG reduced features of inflammation and remodeling. Both agonists showed superior effects to dexamethasone, with CpG being more efficient than R848. This result again supports a TLR9-based therapy as a viable option for the treatment of severe chronic asthma which may present a potential alternative for anti-inflammatory therapy with steroids. Taken together, the results of this thesis support the use of TLR agonists to treat asthma. The most favorable efficacy/safety ratio is to be expected from TLR-based therapies combining TLR4 or TLR9 agonists with allergen in specific immunotherapy. In regard to TLR agonist monotherapy, R848 and CpG showed the most promising profiles, CpG particularly in a model of severe chronic asthma. However, since all TLR agonists used in this study also showed pro-inflammatory potential, the safety aspect of such an approach needs to be taken into account.}, subject = {Toll-like Rezeptor}, language = {en} } @phdthesis{Hsieh2011, author = {Hsieh, Samuel Yu-Lung}, title = {The diversity and ecology of the spider communities of European beech canopy}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-66966}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Ein wesentliches Ziel {\"o}kologischer Forschung ist es, die Frage zu beantworten, wie Arten koexistieren k{\"o}nnen und die biologische Vielfalt erhalten bleibt. Um zu verstehen, wie dabei Gemeinschaften in unterschiedlichen r{\"a}umlich-zeitlichen Dimensionen interagieren, um die biologische Vielfalt zu erhalten, ist ein umfassendes prozessorientiertes Wissen erforderlich. Demzufolge konzentrierte sich meine Studie im Wesentlichen auf die Biodiversit{\"a}t und die sie beeinflussenden raum-zeitlichen {\"o}kologischen Prozesse. Vergleicht man die {\"A}hnlich- bzw. Un{\"a}hnlichkeit der in verschieden alten Best{\"a}nden lebenden Spinnengemeinschaften der Buchen (Fagus sylvatica L.), dann zeigt sich, dass die {\"a}lteste Baumkohorte offensichtlich einzigartige Ressourcen besitzt, welche die Zusammensetzung der Spinnengemeinschaften deutlich pr{\"a}gen. {\"U}ber das Jahr hin zeigten die Spinnengemeinschaften trotz der jahreszeitlich unterschiedlich {\"o}kologischen Randbedingungen eine sich wiederholende, vorhersehbare Dynamik. Der Vergleich {\"u}ber die Jahre ergab, dass das "Neutrale Modell" und das "Nischen-Modell" gleichzeitig funktionieren k{\"o}nnen. Beide sind notwendig, um die Dynamik der in den Buchenkronen der verschiedenen Altersklassen lebenden Spinnengemeinschaften vollst{\"a}ndig erkl{\"a}ren zu k{\"o}nnen.}, subject = {Spinnen}, language = {en} } @phdthesis{Zirkel2011, author = {Zirkel, Janina}, title = {Malaria in Burkina Faso - Chancen f{\"u}r eine neue Strategie mit Hilfe von Methylenblau}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-72583}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Trotz betr{\"a}chtlicher Anstrengung Malaria zu kontrollieren bzw. zu eradizieren, stellt die Krankheit weiterhin eines der gravierendsten Gesundheitsprobleme unseres Jahrtausends dar. Malaria fordert j{\"a}hrlich zwischen 0,7 und 2,7 Millionen Menschenleben, beeintr{\"a}chtigt schulische und soziale Entwicklung und hemmt erheblich das Wirtschaftswachstum der betroffenen L{\"a}nder. In Burkina Faso, einem der {\"a}rmsten L{\"a}nder der Welt, ist Malaria eines der gr{\"o}ßten Gesundheitsprobleme und ca. ein Drittel aller Todesf{\"a}lle werden hier Malaria angelastet. Die sich weiter ausbreiteten Resistenzen gegen die g{\"a}ngigen Malariamedikamente machen die Bek{\"a}mpfung der Malaria zunehmend schwierig. Artemisinin basierende Kombinationstherapien sind aktuell, trotz relativ hoher Therapiekosten und erster Resistenzen, die Erstlinien Behandlung. Effektive und billige neue Kombinationstherapien werden dringend ben{\"o}tigt. In dieser Doktorarbeit wurde das Resistenzpotential von Artemisinin modelliert. Die Homologiemodellierungen unterst{\"u}tzen die These von Krishna und Kollegen von SERCA als einzige Zielstruktur von Artemisinin. Des Weiteren wurde Methylenblau als neues altes Malariamittel evaluiert. Methylenblau ist das erste gegen Malaria eingesetzte Medikament, agiert als ein prooxidatives Agens und inhibiert selektiv und nicht-kompetitiv die P. falciparum Glutathion Reduktase. Die additiven und multiplen Zielprotein Effekte von Methylenblau wurden experimentell untersucht und hier in einem bioinformatischem Modell getestet. Unter dem Einfluss von Methylenblau werden einige Schl{\"u}sselenzyme des Redoxstoffwechsels in ihrer Aktivit{\"a}t beeintr{\"a}chtigt und der Parasit wird verst{\"a}rkt oxidativem Stress ausgesetzt. Des Weiteren konnte in dieser Dr. Arbeit eine starke Kooperationsbereitschaft der urbanen und l{\"a}ndlichen Bev{\"o}lkerung an zuk{\"u}nftigen Malaria Projekten gezeigt werden.}, subject = {Methylenblau}, language = {de} } @phdthesis{Donat2011, author = {Donat, Ulrike}, title = {Detektion und Therapie von Metastasen des humanen Prostatakarzinoms durch das onkolytische Vaccinia-Virus GLV-1h68}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-56421}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Zurzeit sterben j{\"a}hrlich ca. 11.000 M{\"a}nner in Deutschland am Prostatakarzinom. Damit stellt dies die zweith{\"a}ufigste Krebstodesursache von M{\"a}nnern dar. Da das Prostatakarzinom h{\"a}ufig asymptomatisch verl{\"a}uft, wird die Erkrankung oftmals erst so sp{\"a}t erkannt, dass zum Zeitpunkt der Diagnose bereits eine Metastasierung stattgefunden hat. Durch metastasierende Prostatakarzinomzellen werden Lymphknoten, Knochen und Lungen befallen. Es sind zwei unterschiedliche Verbreitungsarten von metastasierenden Tumorzellen beschrieben. Zum einen kann eine Migration {\"u}ber Lymphgef{\"a}ße erfolgen, ein Prozess der als lymphatische Metastasierung bezeichnet wird. Zum anderen k{\"o}nnen Tumorzellen {\"u}ber das Blutsystem im K{\"o}rper zirkulieren: die h{\"a}matogene Metastasierung. In dieser Arbeit wurde die lymphatische Metastasierung der humanen Prostatakarzinomzellline PC-3 im Detail analysiert und Teilaspekte der h{\"a}matogenen Verteilung untersucht. Ausgangspunkt der Untersuchungen bildete die Vergr{\"o}ßerung lumbaler und renaler Lymphknoten in PC-3-Tumor-tragenden M{\"a}usen 60 Tage nach der Implantation von PC-3-Zellen. Es wurde daraufhin der zeitliche Verlauf der Vergr{\"o}ßerung untersucht und festgestellt, dass sowohl das Volumen als auch die Anzahl vergr{\"o}ßerter Lymphknoten von Woche zu Woche nach Implantation der PC-3-Tumore zunehmen. Anschließend wurden alle vergr{\"o}ßerten Lymphknoten bez{\"u}glich des Vorhandenseins von metastasierenden humanen PC-3-Zellen in den M{\"a}usen untersucht. Dies geschah mit Hilfe einer RT-PCR unter Verwendung von Primern f{\"u}r humanes β-Aktin. Sechs Wochen nach Implantation konnten in 90 \% der vergr{\"o}ßerten Lymphknoten PC-3-Zellen nachgewiesen werden. Weiterhin wurde durch lentivirale Transduktion das Gen f{\"u}r das rot fluoreszierende Protein (RFP) in die PC-3-Zellen inseriert, wodurch eine Visualisierung dieser Zellen in der Maus erm{\"o}glicht wurde. Es konnten metastasierende PC-3-RFP-Zellen in lumbalen und renalen Lymphknoten PC-3-RFP-Tumor-tragender M{\"a}use nachgewiesen werden. Ebenso konnte mittels RFP gezeigt werden, dass die Lymphknotenmetastasierung in Abh{\"a}ngigkeit von der Lokalisation des PC-3-RFP-Tumors erfolgt. Es kam zur Metastasierung jener Lymphknoten, in deren Einzugsgebiet sich der PC-3-Tumor befand. Es wurde eine PC-3-RFP-Zellmigration zwischen lumbalen und renalen Lymphknotenmetastasen nachgewiesen und bei immunhistologischen Untersuchungen stellte sich heraus, dass PC-3-RFP-Zellen tats{\"a}chlich in lymphatischen Bahnen zwischen lumbalen und renalen Lymphknotenmetastasen migrieren. Außerdem wurde gezeigt, dass es von Woche zu Woche nach Implantation von PC-3-Zellen zu einer Zunahme der Anzahl von Lymphgef{\"a}ßen in PC-3-Tumoren kommt. Die Zunahme der Lymphgef{\"a}ßdichte korrelierte hierbei positiv mit der Bildung von Lymphknotenmetastasen. Es konnten weiterhin neben Lymphknotenmetastasen h{\"a}matogene Mikrometastasen in den Lungen PC-3-RFP-Tumor-tragender M{\"a}use beobachtet werden. Da die Haupttodesursache von Prostatakarzinompatienten in der Bildung von Metastasen liegt, ist es von herausragender Bedeutung eine effektive Therapie gegen lymphatische und h{\"a}matogene Metastasen zu entwickeln. Aus diesem Grund erlangt die onkolytische Virustherapie große Bedeutung. Deshalb wurde als zweiter Aspekt in dieser Arbeit der Einfluss des onkolytischen Vaccinia-Virus GLV-1h68 auf den Prozess der PC-3-Zellmetastasierung untersucht. Dabei konnte zun{\"a}chst gezeigt werden, dass GLV-1h68 in der Lage ist, erfolgreich sowohl migrierende PC-3-Zellen als auch metastasierende PC-3-Zellen in Lymphknoten zu kolonisieren. In der Folge wurde deshalb ein m{\"o}glicher Metastasen-inhibierender Effekt von GLV-1h68 untersucht. Hierbei stellte sich heraus, dass GLV-1h68 drei Wochen nach intraven{\"o}ser Injektion eine signifikante Reduktion der Anzahl der f{\"u}r PC-3-Zellen positiven Lymphknoten bewirkt. Des Weiteren konnte ein inhibierender Effekt von GLV-1h68 auf die im Blut zirkulierenden PC-3-Zellen und auf h{\"a}matogene Metastasen in den Lungen beobachtet werden. Durch intraven{\"o}se Injektion von GLV-1h68 in PC-3-RFP-Tumor-tragenden M{\"a}usen konnte gezeigt werden, dass es zu einer pr{\"a}ferentiellen Virus-Kolonisierung der Lymphknotenmetastasen im Vergleich zu den Tumoren kommt. Auch nach intraperitonealer und intratumoraler Injektion von GLV-1h68 konnte eine pr{\"a}ferentielle Virus-Kolonisierung der Lymphknotenmetastasen gezeigt werden. Dar{\"u}ber hinaus wurden die Lymph- und Blutgef{\"a}ße von PC-3-Tumoren und Lymphknotenmetastasen analysiert. Hierbei wurde gezeigt, dass es sieben Tage nach intraven{\"o}ser Injektion von GLV-1h68 zu einer signifikanten Abnahme von beiden Gef{\"a}ßarten kam. Es wurde in dieser Arbeit somit gezeigt, dass GLV-1h68 in der Lage ist, sowohl lymphatische als auch h{\"a}matogene Metastasen der Prostatakarzinomzelllinie PC-3 erfolgreich zu eliminieren. Folglich d{\"u}rften onkolytische Vaccinia-Viren ein vielversprechendes Therapeutikum f{\"u}r die Behandlung des fortgeschrittenen Prostatakarzinoms darstellen.}, subject = {Prostatakrebs}, language = {de} } @phdthesis{Hokema2011, author = {Hokema, Anna}, title = {Beeinflussung der Genexpression verschiedener Gene durch Xmrk in Pigmentzelltumoren bei Oryzias latipes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-75616}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Ziel dieser Arbeit ist es ein besseres Verst{\"a}ndinis der molekularen Prozesse der Melanomentstehung und Tumorprogression zu gewinnen. Hierf{\"u}r wurde ein Tiermodell transgener Medakas (Oryzias latipes) verwendet, welche als stabiles Transgen das Konstrukt mitf::xmrk besitzen. Diese Fische entwickelten Pigmentzelltumore, welche f{\"u}r eine Microarrayanalyse herangezogen wurden. Aus diesem Microarraydatensatz wurden 11 Gene ausgew{\"a}hlt, welche in dieser Arbeit n{\"a}her untersucht wurden. Beobachtungen haben ergeben, dass sich bei transgenen Medakas, welche Xmrk exprimieren, verschiedene pigmentierte Hauttumore entwickeln. Diese Tumore wurden je nach ihrem verschiedenen Histiotyp klassifiziert und untersucht. Um einen Eindruck zu gewinnen, wie Xmrk die Transkription verschiedener Gene, welche in der Krebsentstehung und -progression eine wichtige Rolle spielen, beeinflusst, wurden pigmentierte Hauttumore transgener Medakas, so wie zu Vergleichszwecken hyperpigmentierte Haut transgener Medakas und Lymphome und gesunde Organe von Wildtyp-Medakas, untersucht. Mit Hilfe von Real-time-PCR's wurden die folgenden Gene untersucht: G6PC, GAMT, GM2A, MAPK3, NID1, SLC24A5, SPP1, PDIA4, RASL11B, TACC2 und ZFAND5. Dabei konnte festgestellt werden, dass die Expression der Gene GM2A, MAPK3, NID1, PDIA4, RASL11B, SLC24A5 und ZFAND5 von Xmrk beeinflusst wird, w{\"a}hrend dies f{\"u}r die Gene G6PC, GAMT, SPP1 und TACC2 nicht zutrifft. Im Vergleich zu gesunder Haut werden GM2A, MAPK3, PDIA4, RASL11B, SLC24A5 und ZFAND5 in Tumoren h{\"o}her exprimiert. Die Gene G6PC, GAMT, NID1, SPP1 und TACC2 werden dagegen verglichen mit gesunder Haut unver{\"a}ndert oder niedriger exprimiert. Die Bedeutung der erh{\"o}hten Genexpression l{\"a}sst sich in vielen F{\"a}llen zurzeit nur theoretisch erfassen. Eine h{\"o}here Expression von SLC24A5 beispielsweise l{\"a}sst vermuten, dass ein Zusammenhang zwischen der Melaninproduktion und der Zellproliferation besteht. Die {\"U}berexpression von GM2A weist dagegen auf eine Rolle von GM2A als Tumormarker hin. Dahingegen scheint die erniedrigte Expression von GAMT und G6PC Auskunft {\"u}ber den ver{\"a}nderten Stoffwechsel in Tumoren zu geben. Um diese Ergebnisse zu best{\"a}tigen und zu entschl{\"u}sseln wie genau Xmrk die Expression der getesteten Gene beeinflusst, sind allerdings noch weitere funktionelle Studien n{\"o}tig. Generell kommt man zu dem Schluss, dass die Genexpression sich in jedem Tumor unterscheidet. Daher scheint jeder Tumor seinen eigenen Evolutionsweg zu beschreiten.}, subject = {Japank{\"a}rpfling}, language = {de} } @article{WagnerFischerThomaetal.2011, author = {Wagner, Toni U. and Fischer, Andreas and Thoma, Eva C. and Schartl, Manfred}, title = {CrossQuery : A Web Tool for Easy Associative Querying of Transcriptome Data}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-76088}, year = {2011}, abstract = {Enormous amounts of data are being generated by modern methods such as transcriptome or exome sequencing and microarray profiling. Primary analyses such as quality control, normalization, statistics and mapping are highly complex and need to be performed by specialists. Thereafter, results are handed back to biomedical researchers, who are then confronted with complicated data lists. For rather simple tasks like data filtering, sorting and cross-association there is a need for new tools which can be used by non-specialists. Here, we describe CrossQuery, a web tool that enables straight forward, simple syntax queries to be executed on transcriptome sequencing and microarray datasets. We provide deepsequencing data sets of stem cell lines derived from the model fish Medaka and microarray data of human endothelial cells. In the example datasets provided, mRNA expression levels, gene, transcript and sample identification numbers, GO-terms and gene descriptions can be freely correlated, filtered and sorted. Queries can be saved for later reuse and results can be exported to standard formats that allow copy-and-paste to all widespread data visualization tools such as Microsoft Excel. CrossQuery enables researchers to quickly and freely work with transcriptome and microarray data sets requiring only minimal computer skills. Furthermore, CrossQuery allows growing association of multiple datasets as long as at least one common point of correlated information, such as transcript identification numbers or GO-terms, is shared between samples. For advanced users, the object-oriented plug-in and event-driven code design of both server-side and client-side scripts allow easy addition of new features, data sources and data types.}, subject = {CrossQuery}, language = {en} } @article{VandenHoveJakobSchrautetal.2011, author = {Van den Hove, Daniel and Jakob, Sissi Brigitte and Schraut, Karla-Gerlinde and Kenis, Gunter and Schmitt, Angelika Gertrud and Kneitz, Susanne and Scholz, Claus-J{\"u}rgen and Wiescholleck, Valentina and Ortega, Gabriela and Prickaerts, Jos and Steinbusch, Harry and Lesch, Klaus-Peter}, title = {Differential Effects of Prenatal Stress in 5-Htt Deficient Mice: Towards Molecular Mechanisms of Gene x Environment Interactions}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-75795}, year = {2011}, abstract = {Prenatal stress (PS) has been shown to influence the development of the fetal brain and to increase the risk for the development of psychiatric disorders in later life. Furthermore, the variation of human serotonin transporter (5-HTT, SLC6A4) gene was suggested to exert a modulating effect on the association between early life stress and the risk for depression. In the present study, we used a 5-Htt6PS paradigm to investigate whether the effects of PS are dependent on the 5-Htt genotype. For this purpose, the effects of PS on cognition, anxiety- and depression-related behavior were examined using a maternal restraint stress paradigm of PS in C57BL6 wild-type (WT) and heterozygous 5-Htt deficient (5-Htt +/2) mice. Additionally, in female offspring, a genome-wide hippocampal gene expression profiling was performed using the Affymetrix GeneChipH Mouse Genome 430 2.0 Array. 5-Htt +/2 offspring showed enhanced memory performance and signs of reduced anxiety as compared to WT offspring. In contrast, exposure of 5-Htt +/2 mice to PS was associated with increased depressive-like behavior, an effect that tended to be more pronounced in female offspring. Further, 5-Htt genotype, PS and their interaction differentially affected the expression of numerous genes and related pathways within the female hippocampus. Specifically, MAPK and neurotrophin signaling were regulated by both the 5-Htt +/2 genotype and PS exposure, whereas cytokine and Wnt signaling were affected in a 5-Htt genotype6PS manner, indicating a gene6environment interaction at the molecular level. In conclusion, our data suggest that although the 5-Htt +/2 genotype shows clear adaptive capacity, 5-Htt +/2 mice -particularly females- at the same time appear to be more vulnerable to developmental stress exposure when compared to WT offspring. Moreover, hippocampal gene expression profiles suggest that distinct molecular mechanisms mediate the behavioral effects of the 5-Htt genotype, PS exposure, and their interaction.}, subject = {Medizin}, language = {en} } @article{OndruschKreft2011, author = {Ondrusch, Nicolai and Kreft, J{\"u}rgen}, title = {Blue and Red Light Modulates SigB-Dependent Gene Transcription, Swimming Motility and Invasiveness in Listeria monocytogenes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-75451}, year = {2011}, abstract = {Background: In a number of gram-positive bacteria, including Listeria, the general stress response is regulated by the alternative sigma factor B (SigB). Common stressors which lead to the activation of SigB and the SigB-dependent regulon are high osmolarity, acid and several more. Recently is has been shown that also blue and red light activates SigB in Bacillus subtilis. Methodology/Principal Findings: By qRT-PCR we analyzed the transcriptional response of the pathogen L. monocytogenes to blue and red light in wild type bacteria and in isogenic deletion mutants for the putative blue-light receptor Lmo0799 and the stress sigma factor SigB. It was found that both blue (455 nm) and red (625 nm) light induced the transcription of sigB and SigB-dependent genes, this induction was completely abolished in the SigB mutant. The blue-light effect was largely dependent on Lmo0799, proving that this protein is a genuine blue-light receptor. The deletion of lmo0799 enhanced the red-light effect, the underlying mechanism as well as that of SigB activation by red light remains unknown. Blue light led to an increased transcription of the internalin A/B genes and of bacterial invasiveness for Caco-2 enterocytes. Exposure to blue light also strongly inhibited swimming motility of the bacteria in a Lmo0799- and SigB-dependent manner, red light had no effect there. Conclusions/Significance: Our data established that visible, in particular blue light is an important environmental signal with an impact on gene expression and physiology of the non-phototrophic bacterium L. monocytogenes. In natural environments these effects will result in sometimes random but potentially also cyclic fluctuations of gene activity, depending on the light conditions prevailing in the respective habitat.}, subject = {Listeria monocytogenes}, language = {en} } @article{EndesfelderMalkuschFlottmannetal.2011, author = {Endesfelder, Ulrike and Malkusch, Sebastian and Flottmann, Benjamin and Mondry, Justine and Liguzinski, Piotr and Verveer, Peter J. and Heilemann, Mike}, title = {Chemically Induced Photoswitching of Fluorescent Probes - A General Concept for Super-Resolution Microscopy}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-74896}, year = {2011}, abstract = {We review fluorescent probes that can be photoswitched or photoactivated and are suited for single-molecule localization based super-resolution microscopy. We exploit the underlying photochemical mechanisms that allow photoswitching of many synthetic organic fluorophores in the presence of reducing agents, and study the impact of these on the photoswitching properties of various photoactivatable or photoconvertible fluorescent proteins. We have identified mEos2 as a fluorescent protein that exhibits reversible photoswitching under various imaging buffer conditions and present strategies to characterize reversible photoswitching. Finally, we discuss opportunities to combine fluorescent proteins with organic fluorophores for dual-color photoswitching microscopy.}, subject = {Super-Resolution Microscopy}, language = {en} } @article{NiewaldaVoellerEschbachetal.2011, author = {Niewalda, Thomas and V{\"o}ller, Thomas and Eschbach, Claire and Ehmer, Julia and Chou, Wen-Chuang and Timme, Marc and Fiala, Andr{\´e} and Gerber, Bertram}, title = {A Combined Perceptual, Physico-Chemical, and ImagingApproach to 'Odour-Distances' Suggests a CategorizingFunction of the Drosophila Antennal Lobe}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-74769}, year = {2011}, abstract = {How do physico-chemical stimulus features, perception, and physiology relate? Given the multi-layered and parallel architecture of brains, the question specifically is where physiological activity patterns correspond to stimulus features and/ or perception. Perceived distances between six odour pairs are defined behaviourally from four independent odour recognition tasks. We find that, in register with the physico-chemical distances of these odours, perceived distances for 3-octanol and n-amylacetate are consistently smallest in all four tasks, while the other five odour pairs are about equally distinct. Optical imaging in the antennal lobe, using a calcium sensor transgenically expressed in only first-order sensory or only second-order olfactory projection neurons, reveals that 3-octanol and n-amylacetate are distinctly represented in sensory neurons, but appear merged in projection neurons. These results may suggest that within-antennal lobe processing funnels sensory signals into behaviourally meaningful categories, in register with the physico-chemical relatedness of the odours.}, subject = {Drosophila Antennal Lobe}, language = {en} } @article{WegertBausenweinKneitzetal.2011, author = {Wegert, Jenny and Bausenwein, Sabrina and Kneitz, Susanne and Roth, Sabine and Graf, Norbert and Geissinger, Eva and Gessler, Manfred}, title = {Retinoic acid pathway activity in Wilms tumors and characterization of biological responses in vitro}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69137}, year = {2011}, abstract = {Background: Wilms tumor (WT) is one of the most common malignancies in childhood. With current therapy protocols up to 90\% of patients can be cured, but there is still a need to improve therapy for patients with aggressive WT and to reduce treatment intensity where possible. Prior data suggested a deregulation of the retinoic acid (RA) signaling pathway in high-risk WT, but its mode of action remained unclear. Results: The association of retinoid signaling and clinical parameters could be validated in a large independent tumor set, but its relevance in primary nephrectomy tumors from very young children may be different. Reduced RA pathway activity and MYCN overexpression were found in high risk tumors as opposed to tumors with low/ intermediate risk, suggesting a beneficial impact of RA especially on advanced WT. To search for possible modes of action of retinoids as novel therapeutic options, primary tumor cell cultures were treated in vitro with all-trans-RA (ATRA), 9cis-RA, fenretinide and combinations of retinoids and a histone deacetylase (HDAC) inhibitor. Genes deregulated in high risk tumors showed opposite changes upon treatment suggesting a positive effect of retinoids. 6/7 primary cultures tested reduced proliferation, irrespective of prior RA signaling levels. The only variant culture was derived from mesoblastic nephroma, a distinct childhood kidney neoplasm. Retinoid/HDAC inhibitor combinations provided no synergistic effect. ATRA and 9cis-RA induced morphological changes suggestive of differentiation, while fenretinide induced apoptosis in several cultures tested. Microarray analysis of ATRA treated WT cells revealed differential expression of many genes involved in extracellular matrix formation and osteogenic, neuronal or muscle differentiation. The effects documented appear to be reversible upon drug withdrawal, however. Conclusions: Altered retinoic acid signaling has been validated especially in high risk Wilms tumors. In vitro testing of primary tumor cultures provided clear evidence of a potential utility of retinoids in Wilms tumor treatment based on the analysis of gene expression, proliferation, differentiation and apoptosis.}, subject = {Krebs}, language = {en} } @article{KronauerPetersSchoningetal.2011, author = {Kronauer, Daniel J. C. and Peters, Marcell K. and Schoning, Caspar and Boomsma, Jacobus J.}, title = {Hybridization in East African swarm-raiding army ants}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68798}, year = {2011}, abstract = {Background: Hybridization can have complex effects on evolutionary dynamics in ants because of the combination of haplodiploid sex-determination and eusociality. While hybrid non-reproductive workers have been found in a range of species, examples of gene-flow via hybrid queens and males are rare. We studied hybridization in East African army ants (Dorylus subgenus Anomma) using morphology, mitochondrial DNA sequences, and nuclear microsatellites. Results: While the mitochondrial phylogeny had a strong geographic signal, different species were not recovered as monophyletic. At our main study site at Kakamega Forest, a mitochondrial haplotype was shared between a "Dorylus molestus-like" and a "Dorylus wilverthi-like" form. This pattern is best explained by introgression following hybridization between D. molestus and D. wilverthi. Microsatellite data from workers showed that the two morphological forms correspond to two distinct genetic clusters, with a significant proportion of individuals being classified as hybrids. Conclusions: We conclude that hybridization and gene-flow between the two army ant species D. molestus and D. wilverthi has occurred, and that mating between the two forms continues to regularly produce hybrid workers. Hybridization is particularly surprising in army ants because workers have control over which males are allowed to mate with a young virgin queen inside the colony.}, subject = {Zoologie}, language = {en} } @article{VogelLoeschbergerSaueretal.2011, author = {Vogel, Benjamin and L{\"o}schberger, Anna and Sauer, Markus and Hock, Robert}, title = {Cross-linking of DNA through HMGA1 suggests a DNA scaffold}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68865}, year = {2011}, abstract = {Binding of proteins to DNA is usually considered 1D with one protein bound to one DNA molecule. In principle, proteins with multiple DNA binding domains could also bind to and thereby cross-link different DNA molecules. We have investigated this possibility using high-mobility group A1 (HMGA1) proteins, which are architectural elements of chromatin and are involved in the regulation of multiple DNA-dependent processes. Using direct stochastic optical reconstruction microscopy (dSTORM), we could show that overexpression of HMGA1a-eGFP in Cos-7 cells leads to chromatin aggregation. To investigate if HMGA1a is directly responsible for this chromatin compaction we developed a DNA cross-linking assay. We were able to show for the first time that HMGA1a can cross-link DNA directly. Detailed analysis using point mutated proteins revealed a novel DNA cross-linking domain. Electron microscopy indicates that HMGA1 proteins are able to create DNA loops and supercoils in linearized DNA confirming the cross-linking ability of HMGA1a. This capacity has profound implications for the spatial organization of DNA in the cell nucleus and suggests cross-linking activities for additional nuclear proteins.}, subject = {DNA}, language = {en} } @article{GoebMeyerNatusBenaventeetal.2011, author = {G{\"o}b, Eva and Meyer-Natus, Elisabeth and Benavente, Ricardo and Alsheimer, Manfred}, title = {Expression of individual mammalian Sun1 isoforms depends on the cell type}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68750}, year = {2011}, abstract = {Mammalian Sun1 belongs to an evolutionarily conserved family of inner nuclear membrane proteins, which are known as SUN domain proteins. SUN domain proteins interact with KASH domain partners to form bridging complexes, so-called LINC complexes, that physically connect the nuclear interior to the cytoskeleton. LINC complexes are critical for nuclear integrity and play fundamental roles in nuclear positioning, shaping and movement. The mammalian genome codes for at least five different SUN domain proteins used for the formation of a number of different LINC complexes. Recently, we reported on the identification of everal Sun1 isoforms, which tremendously enlarges the alternatives to form functional LINC complexes. We now confirmed that Sun1 actually exists in at least seven distinct splice variants. Besides that, we observed that expression of individual Sun1 isoforms remarkably depends on the cell type, suggesting a cell type-specific adaption of Sun1 dependent LINC complexes to specific cellular and physiological requirements.}, subject = {Biologie}, language = {en} } @phdthesis{Vogel2011, author = {Vogel, Benjamin}, title = {Organisation von Chromatin durch HMGA1 Proteine}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-65295}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {HMGA1 Proteine sind kleine, basische, Nicht-Histon Proteine, die in L{\"o}sung keine Struktur aufweisen, durch drei AT-Haken, als DNA-Bindungsmotive, gekennzeichnet sind und pr{\"a}ferentiell an die kleine Furche der DNA binden. Als differenziell exprimierte Architekturelemente des Chromatins erf{\"u}llen sie wichtige Funktionen bei der Regulation DNA abh{\"a}ngiger Prozesse in Zellen und w{\"a}hrend Entwicklungsprozessen. Aberrante Expressionen f{\"u}hren zu Entwicklungsdefekten und Krebs. In dieser Arbeit wurde der Einfluss von HMGA1 Proteinen auf die Organisation des Chromatins untersucht. Als Modell diente dabei zun{\"a}chst die Differenzierung von C2C12 Muskelvorl{\"a}uferzellen. Wie in einer fr{\"u}heren Arbeit gezeigt wurde, ist die Herunterregulation von HMGA1a essentiell f{\"u}r den Eintritt von C2C12 Zellen in die Myogenese. Eine konstante {\"U}berexpression von HMGA1a-eGFP hingegen verhindert die Muskeldifferenzierung durch Beeinflussung der Expression myogenesespezifischer Gene und Etablierung einer stabilen Chromatinstruktur. Wie in der vorliegenden Arbeit herausgefunden wurde, nimmt die differenzielle HMGA1a Expression nicht nur Einfluss auf die Expression muskelspezifischer Gene, sondern auch auf die globale Zusammensetzung des Chromatins durch eine reduzierte Expression von H1 Histonen und einer aberranten Expression von HMGB1, HMGN1 und HP1 Proteinen. HMGA1a wurde zusammen mit ORC Proteinen eine Funktion bei der Definition von Replikationsurspr{\"u}ngen in eukaryotischen Zellen zugesprochen. ORC Proteine wurden auch als Komponenten des Heterochromatins und als Interaktionspartner von HP1α identifiziert. Hier konnte mit Hilfe von Co-Immunpr{\"a}zipitationen, Pull-down Assays und Verdr{\"a}ngungsexperimenten gezeigt werden, dass HMGA1 ein weiterer, direkter Interaktionspartner von ORC Proteinen im Heterochromatin ist und zusammen mit HP1α kooperiert. Pull-down-, Verdr{\"a}ngungs- und siRNA-Experimente zeigten zudem, dass HMGA1 zwar nicht direkt mit HP1α interagiert, die Kooperation der Proteine {\"u}ber ORC aber dennoch wichtig f{\"u}r die Aufrechterhaltung der Heterochromatinsstruktur ist. Damit erweisen sich HMGA1 Proteine als wichtige Stabilisierungsfaktoren des Heterochromatins. Bislang ging man davon aus, dass HMGA1 Molek{\"u}le linear, also eindimensional, an ein DNA Molek{\"u}l binden. Das Vorhandensein von drei DNA-Bindungsmotiven und die eher struktur- als sequenzabh{\"a}ngige Bindung an die DNA lassen vermuten, dass HMGA1 Proteine auch gleichzeitig an benachbarte DNA-Str{\"a}nge, also auch dreidimensional, binden k{\"o}nnten. Bekr{\"a}ftigt wurde diese Vermutung durch die Bildung von Chromatinaggregaten in Zellen die HMGA1a-eGFP {\"u}berexprimierten. Dies wurde mittels konfokaler und hochaufl{\"o}sender Mikroskopie (dSTORM) analysiert. Um das Potential einer DNA-Quervernetzung durch HMGA1 Proteine nachzuweisen, wurde eine neue Methode entwickelt. Mit Hilfe eines neuartigen DNA Cross-linking Assays wurde nachgewiesen, dass HMGA1 Proteine in der Lage sind, zwei individuelle DNA Str{\"a}nge zu vernetzen. Zudem wurde eine neue Dom{\"a}ne in HMGA1 entdeckt die maßgeblich zum Cross-linking beitr{\"a}gt. Elektronenmikroskopische Analysen best{\"a}tigten, dass HMGA1 Proteine in der Lage sind Kreuzungen und Schleifen in DNA Molek{\"u}len zu erzeugen. Diese Ergebnisse unterst{\"u}tzen die Vermutung, dass HMGA1 Proteine im Zellkern ein DNA Ger{\"u}st bilden k{\"o}nnen, das Einfluss auf die zelltypische Chromatinorganisation nimmt und dadurch DNA abh{\"a}ngige Prozesse beeinflusst. In wie weit eine HMGA1 induzierte DNA Quervernetzung in vivo zum Beispiel in Chromozentren von C2C12 Zellen oder in Krebszellen, in denen HMGA1 Proteine stark {\"u}berexprimiert sind, eine Rolle spielen, m{\"u}ssen k{\"u}nftige Untersuchungen zeigen. In dieser Arbeit konnte also gezeigt werden, dass HMGA1 Proteine die Chromatinstruktur auf drei Ebenen organisieren k{\"o}nnen: Durch Beeinflussung der Chromatinzusammensetzung durch Ver{\"a}nderung der Expression von Chromatinproteinen, durch Interaktion mit anderen Architekturelementen des Chromatins und durch Organisation eines potentiellen DNA Ger{\"u}sts.}, subject = {Chromatin}, language = {de} } @phdthesis{Philippi2011, author = {Philippi, Nicole}, title = {Modellierung von Signalwegen in verschiedenen biologischen Systemen}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-57690}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Die Apoptose der Leberzellen ist abh{\"a}ngig von externen Signalen wie beispielsweise Komponenten der Extrazellul{\"a}ren Matrix sowie anderen Zell-Zell-Kontakten, welche von einer Vielfalt und Vielzahl an Knoten verarbeitet werden. Einige von ihnen wurden im Rahmen dieser Arbeit auf ihre Systemeffekte hin unter- sucht. Trotz verschiedener {\"a}ußerer Einfl{\"u}sse und nat{\"u}rlicher Selektion ist das System daraufhin optimiert, eine kleine Anzahl verschiedener und klar voneinander unterscheidbarer Systemzust{\"a}nde anzunehmen. Die verschiedenartigen Einfl{\"u}sse und Crosstalk-Mechanismen dienen der Optimierung der vorhandenen Systemzust{\"a}nde. Das in dieser Arbeit vorgestellte Modell zeigt zwei apoptotische sowie zwei nicht-apoptotische stabile Systemzust{\"a}nde, wobei der Grad der Aktivierung eines Knotens bis zu dem Moment stark variieren kann, in welchem der absolute Systemzustand selbst ver{\"a}ndert wird (Philippi et al., BMC Systems Biology,2009) [1]. Dieses Modell stellt zwar eine Vereinfachung des gesamten zellul{\"a}ren Netzwerkes und seiner verschiedenen Zust{\"a}nde dar, ist aber trotz allem in der Lage, unabh{\"a}ngig von detaillierten kinetischen Daten und Parametern der einzelnen Knoten zu agieren. Gleichwohl erlaubt das Modell mit guter qualitativer {\"U}bereinstimmung die Apoptose als Folge einer Stimulation mit FasL zu modellieren. Weiterhin umfasst das Modell sowohl Crosstalk-M{\"o}glichkeiten des Collagen-Integrin-Signalwegs, ebenso ber{\"u}cksichtigt es die Auswirkungen der genetischen Deletion von Bid sowie die Konsequenzen einer viralen Infektion. In einem zweiten Teil werden andere Anwendungsm{\"o}glichkeiten dargestellt. Hormonale Signale in Pflanzen, Virusinfektionen und intrazellul{\"a}re Kommunikation werden semi-quantitativ modelliert. Auch hier zeigte sich eine gute Ubereinstimmung der Modelle mit den experimentellen Daten.}, subject = {Systembiologie}, language = {de} } @phdthesis{Thoma2011, author = {Thoma, Eva Christina}, title = {Directed differentiation of pluripotent stem cells induced by single genes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-54706}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Pluripotency describes the ability of stem cells to form every cell type of the body.. Pluripotent stem cells are e.g. embryonic stem cells (ESCs), but also the so called induced pluripotent stem cells (IPS cells), that are generated by reprogramming differentiated somatic cells into a pluripotent state. Furthermore, it has been shown that spermatogonia (SG) derived from adult testes of mouse or human are pluripotent. Because of their ability to differentiate into every somatic cell type, pluripotent stem cells have a unique status in research and regenerative medicine. For the latter, they offer a valuable opportunity to replace destroyed tissues or organs. For basic research, stem cells represent a useful system to study differentiation or developmental processes that are difficult to access in the physiological situation e.g. during embryogenesis. Both applications, however, require methods that allow efficient and directed differentiation of stem cells into defined specialized cell types. This study first aims to investigate the differentiation potential of SG derived from the teleost fish medaka (Oryzias latipes). My results demonstrate that medaka SG are able to form different somatic cell types, namely adipocytes, melanocytes, osteoblasts, and neurons. This indicates that medake SG have retained a broad differentiation potential suggesting that pluripotency is not restricted to mouse and human SG but might be conserved among vertebrates. Next, I wanted to establish a differentiation method that is solely based on ectopic expression of genes known to be essential for the formation of certain somatic cell types - so called master regulators (MRs). My findings show that ectopic expression of the melanocyte-specific transcription factor mitf-m that has previously been shown to induce differentiation of medaka ESCs into pigment cells resulted in the formation of the same cell type in medaka SG. This approach could be used to generate other somatic cell types. Thus, ectopic expression of the MRs cbfa1 and mash1 in MF-SG was sufficient to induce differentiation into osteoblasts and neurons, respectively. Interestingly, these differentiation processes included the activation of genes that are expressed earlier during embryogenesis than the differentiation-inducing MR. Furthermore, my findings show that the approach of MR-induced differentiation can be transferred to mammalian stem cell systems. Ectopic expression of the neural transcription factor ngn2 was sufficient to induce efficient and rapid differentiation of neurons in mouse ESCs. This differentiation process also included the induction of genes that in vivo are activated at earlier stages that ngn2. By generating a transgenic cell line allowing induction of ectopic ngn2 expression, it was possible to obtain a relatively pure culture of functional neurons. Ngn2-induced differentiation did not require any additional signals and occurred even under pluripotency promoting conditions. Moreover, ectopic expression of ngn2 did also induce the formation of cells with neuronal morphology in IPS cells indicating that MR-induced differentiation is operative in different stem cell types. Furthermore, protein transduction of Ngn2 into mouse ESCs also resulted in a neuronal differentiation process up to the appearance of neural precursor cells. Last, my results show that MR-induced differentiation can also be used to generate other cell types than neurons from mouse ESCs. Myoblasts and macrophage-like cells were generated by ectopic expression of the MRs myoD and cebpa, respectively. Using transgenic cell lines enabling induction of MR expression it was possible to obtain mixed cultures with two different differentiation processes occurring in parallel. Altogether this study shows that ectopic expression of single genes is sufficient to induce directed differentiation of stem cells into defined cell types. The feasibility of this approach was demonstrated for different MRs and consequently different somatic cell types. Furthermore, MR induced differentiation was operative in different stem cell types from fish and mouse. Thus, one can conclude that certain genes are able to define cell fates in in vitro stem cell systems and that this cell fate defining potential appears to be a conserved feature in vertebrates. These findings therefore provide new insights in the role of MRs in cell commitment and differentiation processes. Furthermore, this study presents a new method to induce directed differentiation of stem cells that offers several advantages regarding efficiency, rapidness, and reproducibility. MR-induced differentiation therefore represents a promising tool for both stem cell research and regenerative medicine.}, subject = {Stammzelle}, language = {en} } @phdthesis{Schneider2011, author = {Schneider, Christof}, title = {Detecting the influence of different potential stress factors on the behavior of the honeybee Apis mellifera using Radiofrequency Identification (RFID)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-71344}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {This study was conducted to determine the influence of different stress factors on the honeybee Apis mellifera. The investigation was motivated by previous experiments that suggested the existence of an unspecific defense mechanism causing a generalized change of flight behavior after the onset of different diseases. This mechanism is thought to impede the ability of flight bees to return to their respective colonies thereby removing the disease from the colony over time. During the last years, the existence of such a "suicidal behavior" was supported by further studies. Thus, an unnoticed, potentially highly effective defense mechanism of social insects was revealed whose spectrum of activity and physiological basics require further investigation. Suggesting that the reaction by the bees is unspecific to different diseases as well as to other potential stress factors, this study was designed to investigate the influence of pathogens, insecticides, and different brood rearing temperatures on different parameters like lifespan, foraging activity, and foraging trip duration of worker bees.}, subject = {Biene}, language = {en} } @article{WangorschButtMarketal.2011, author = {Wangorsch, Gaby and Butt, Elke and Mark, Regina and Hubertus, Katharina and Geiger, J{\"o}rg and Dandekar, Thomas and Dittrich, Marcus}, title = {Time-resolved in silico modeling of fine-tuned cAMP signaling in platelets: feedback loops, titrated phosphorylations and pharmacological modulation}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69145}, year = {2011}, abstract = {Background: Hemostasis is a critical and active function of the blood mediated by platelets. Therefore, the prevention of pathological platelet aggregation is of great importance as well as of pharmaceutical and medical interest. Endogenous platelet inhibition is predominantly based on cyclic nucleotides (cAMP, cGMP) elevation and subsequent cyclic nucleotide-dependent protein kinase (PKA, PKG) activation. In turn, platelet phosphodiesterases (PDEs) and protein phosphatases counterbalance their activity. This main inhibitory pathway in human platelets is crucial for countervailing unwanted platelet activation. Consequently, the regulators of cyclic nucleotide signaling are of particular interest to pharmacology and therapeutics of atherothrombosis. Modeling of pharmacodynamics allows understanding this intricate signaling and supports the precise description of these pivotal targets for pharmacological modulation. Results: We modeled dynamically concentration-dependent responses of pathway effectors (inhibitors, activators, drug combinations) to cyclic nucleotide signaling as well as to downstream signaling events and verified resulting model predictions by experimental data. Experiments with various cAMP affecting compounds including antiplatelet drugs and their combinations revealed a high fidelity, fine-tuned cAMP signaling in platelets without crosstalk to the cGMP pathway. The model and the data provide evidence for two independent feedback loops: PKA, which is activated by elevated cAMP levels in the platelet, subsequently inhibits adenylyl cyclase (AC) but as well activates PDE3. By multi-experiment fitting, we established a comprehensive dynamic model with one predictive, optimized and validated set of parameters. Different pharmacological conditions (inhibition, activation, drug combinations, permanent and transient perturbations) are successfully tested and simulated, including statistical validation and sensitivity analysis. Downstream cyclic nucleotide signaling events target different phosphorylation sites for cAMP- and cGMP-dependent protein kinases (PKA, PKG) in the vasodilator-stimulated phosphoprotein (VASP). VASP phosphorylation as well as cAMP levels resulting from different drug strengths and combined stimulants were quantitatively modeled. These predictions were again experimentally validated. High sensitivity of the signaling pathway at low concentrations is involved in a fine-tuned balance as well as stable activation of this inhibitory cyclic nucleotide pathway. Conclusions: On the basis of experimental data, literature mining and database screening we established a dynamic in silico model of cyclic nucleotide signaling and probed its signaling sensitivity. Thoroughly validated, it successfully predicts drug combination effects on platelet function, including synergism, antagonism and regulatory loops.}, subject = {Vasodilatator-stimuliertes Phosphoprotein}, language = {en} } @article{AlbrechtSharmaDittrichetal.2011, author = {Albrecht, Marco and Sharma, Cynthia M. and Dittrich, Marcus T. and M{\"u}ller, Tobias and Reinhardt, Richard and Vogel, J{\"o}rg and Rudel, Thomas}, title = {The Transcriptional Landscape of Chlamydia pneumoniae}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69116}, year = {2011}, abstract = {Background: Gene function analysis of the obligate intracellular bacterium Chlamydia pneumoniae is hampered by the facts that this organism is inaccessible to genetic manipulations and not cultivable outside the host. The genomes of several strains have been sequenced; however, very little information is available on the gene structure and transcriptome of C. pneumoniae. Results: Using a differential RNA-sequencing approach with specific enrichment of primary transcripts, we defined the transcriptome of purified elementary bodies and reticulate bodies of C. pneumoniae strain CWL-029; 565 transcriptional start sites of annotated genes and novel transcripts were mapped. Analysis of adjacent genes for cotranscription revealed 246 polycistronic transcripts. In total, a distinct transcription start site or an affiliation to an operon could be assigned to 862 out of 1,074 annotated protein coding genes. Semi-quantitative analysis of mapped cDNA reads revealed significant differences for 288 genes in the RNA levels of genes isolated from elementary bodies and reticulate bodies. We have identified and in part confirmed 75 novel putative non-coding RNAs. The detailed map of transcription start sites at single nucleotide resolution allowed for the first time a comprehensive and saturating analysis of promoter consensus sequences in Chlamydia. Conclusions: The precise transcriptional landscape as a complement to the genome sequence will provide new insights into the organization, control and function of genes. Novel non-coding RNAs and identified common promoter motifs will help to understand gene regulation of this important human pathogen.}, subject = {Chlamydia pneumoniae}, language = {en} } @article{BrandstaetterRoesslerKleineidam2011, author = {Brandst{\"a}tter, Andreas and R{\"o}ssler, W. and Kleineidam, C. J.}, title = {Friends and foes from an ant brain's point of view - neuronal correlates of colony odors in a social insect}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69046}, year = {2011}, abstract = {Background: Successful cooperation depends on reliable identification of friends and foes. Social insects discriminate colony members (nestmates/friends) from foreign workers (non-nestmates/foes) by colony-specific, multi-component colony odors. Traditionally, complex processing in the brain has been regarded as crucial for colony recognition. Odor information is represented as spatial patterns of activity and processed in the primary olfactory neuropile, the antennal lobe (AL) of insects, which is analogous to the vertebrate olfactory bulb. Correlative evidence indicates that the spatial activity patterns reflect odor-quality, i.e., how an odor is perceived. For colony odors, alternatively, a sensory filter in the peripheral nervous system was suggested, causing specific anosmia to nestmate colony odors. Here, we investigate neuronal correlates of colony odors in the brain of a social insect to directly test whether they are anosmic to nestmate colony odors and whether spatial activity patterns in the AL can predict how odor qualities like ''friend'' and ''foe'' are attributed to colony odors. Methodology/Principal Findings: Using ant dummies that mimic natural conditions, we presented colony odors and investigated their neuronal representation in the ant Camponotus floridanus. Nestmate and non-nestmate colony odors elicited neuronal activity: In the periphery, we recorded sensory responses of olfactory receptor neurons (electroantennography), and in the brain, we measured colony odor specific spatial activity patterns in the AL (calcium imaging). Surprisingly, upon repeated stimulation with the same colony odor, spatial activity patterns were variable, and as variable as activity patterns elicited by different colony odors. Conclusions: Ants are not anosmic to nestmate colony odors. However, spatial activity patterns in the AL alone do not provide sufficient information for colony odor discrimination and this finding challenges the current notion of how odor quality is coded. Our result illustrates the enormous challenge for the nervous system to classify multi-component odors and indicates that other neuronal parameters, e.g., precise timing of neuronal activity, are likely necessary for attribution of odor quality to multi-component odors.}, subject = {Ameisen}, language = {en} } @article{LeonhardtSchmittBluethgen2011, author = {Leonhardt, Sara D. and Schmitt, Thomas and Bl{\"u}thgen, Nico}, title = {Tree Resin Composition, Collection Behavior and Selective Filters Shape Chemical Profiles of Tropical Bees (Apidae: Meliponini)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69035}, year = {2011}, abstract = {The diversity of species is striking, but can be far exceeded by the chemical diversity of compounds collected, produced or used by them. Here, we relate the specificity of plant-consumer interactions to chemical diversity applying a comparative network analysis to both levels. Chemical diversity was explored for interactions between tropical stingless bees and plant resins, which bees collect for nest construction and to deter predators and microbes. Resins also function as an environmental source for terpenes that serve as appeasement allomones and protection against predators when accumulated on the bees' body surfaces. To unravel the origin of the bees' complex chemical profiles, we investigated resin collection and the processing of resin-derived terpenes. We therefore analyzed chemical networks of tree resins, foraging networks of resin collecting bees, and their acquired chemical networks. We revealed that 113 terpenes in nests of six bee species and 83 on their body surfaces comprised a subset of the 1,117 compounds found in resins from seven tree species. Sesquiterpenes were the most variable class of terpenes. Albeit widely present in tree resins, they were only found on the body surface of some species, but entirely lacking in others. Moreover, whereas the nest profile of Tetragonula melanocephala contained sesquiterpenes, its surface profile did not. Stingless bees showed a generalized collecting behavior among resin sources, and only a hitherto undescribed species-specific ''filtering'' of resin-derived terpenes can explain the variation in chemical profiles of nests and body surfaces fromdifferent species. The tight relationship between bees and tree resins of a large variety of species elucidates why the bees' surfaces contain a much higher chemodiversity than other hymenopterans.}, subject = {Stachellose Biene}, language = {en} } @article{KraussGallenbergerSteffanDewenter2011, author = {Krauss, Jochen and Gallenberger, Iris and Steffan-Dewenter, Ingolf}, title = {Decreased Functional Diversity and Biological Pest Control in Conventional Compared to Organic Crop Fields}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69005}, year = {2011}, abstract = {Organic farming is one of the most successful agri-environmental schemes, as humans benefit from high quality food, farmers from higher prices for their products and it often successfully protects biodiversity. However there is little knowledge if organic farming also increases ecosystem services like pest control. We assessed 30 triticale fields (15 organic vs. 15 conventional) and recorded vascular plants, pollinators, aphids and their predators. Further, five conventional fields which were treated with insecticides were compared with 10 non-treated conventional fields. Organic fields had five times higher plant species richness and about twenty times higher pollinator species richness compared to conventional fields. Abundance of pollinators was even more than one-hundred times higher on organic fields. In contrast, the abundance of cereal aphids was five times lower in organic fields, while predator abundances were three times higher and predator-prey ratios twenty times higher in organic fields, indicating a significantly higher potential for biological pest control in organic fields. Insecticide treatment in conventional fields had only a short-term effect on aphid densities while later in the season aphid abundances were even higher and predator abundances lower in treated compared to untreated conventional fields. Our data indicate that insecticide treatment kept aphid predators at low abundances throughout the season, thereby significantly reducing top-down control of aphid populations. Plant and pollinator species richness as well as predator abundances and predator-prey ratios were higher at field edges compared to field centres, highlighting the importance of field edges for ecosystem services. In conclusion organic farming increases biodiversity, including important functional groups like plants, pollinators and predators which enhance natural pest control. Preventative insecticide application in conventional fields has only short-term effects on aphid densities but long-term negative effects on biological pest control. Therefore conventional farmers should restrict insecticide applications to situations where thresholds for pest densities are reached.}, subject = {Landwirtschaft}, language = {en} }