TY - JOUR A1 - Englmeier, Jana A1 - Mitesser, Oliver A1 - Benbow, M. Eric A1 - Hothorn, Torsten A1 - von Hoermann, Christian A1 - Benjamin, Caryl A1 - Fricke, Ute A1 - Ganuza, Cristina A1 - Haensel, Maria A1 - Redlich, Sarah A1 - Riebl, Rebekka A1 - Rojas Botero, Sandra A1 - Rummler, Thomas A1 - Steffan-Dewenter, Ingolf A1 - Stengel, Elisa A1 - Tobisch, Cynthia A1 - Uhler, Johannes A1 - Uphus, Lars A1 - Zhang, Jie A1 - Müller, Jörg T1 - Diverse effects of climate, land use, and insects on dung and carrion decomposition JF - Ecosystems N2 - Land-use intensification and climate change threaten ecosystem functions. A fundamental, yet often overlooked, function is decomposition of necromass. The direct and indirect anthropogenic effects on decomposition, however, are poorly understood. We measured decomposition of two contrasting types of necromass, rat carrion and bison dung, on 179 study sites in Central Europe across an elevational climate gradient of 168–1122 m a.s.l. and within both local and regional land uses. Local land-use types included forest, grassland, arable fields, and settlements and were embedded in three regional land-use types (near-natural, agricultural, and urban). The effects of insects on decomposition were quantified by experimental exclusion, while controlling for removal by vertebrates. We used generalized additive mixed models to evaluate dung weight loss and carrion decay rate along elevation and across regional and local land-use types. We observed a unimodal relationship of dung decomposition with elevation, where greatest weight loss occurred between 600 and 700 m, but no effects of local temperature, land use, or insects. In contrast to dung, carrion decomposition was continuously faster with both increasing elevation and local temperature. Carrion reached the final decomposition stage six days earlier when insect access was allowed, and this did not depend on land-use effect. Our experiment identified different major drivers of decomposition on each necromass form. The results show that dung and carrion decomposition are rather robust to local and regional land use, but future climate change and decline of insects could alter decomposition processes and the self-regulation of ecosystems. KW - decay KW - ecosystem function KW - global change KW - land-use intensification KW - necrobiome KW - urbanization Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-325064 SN - 1432-9840 VL - 26 IS - 2 ER - TY - JOUR A1 - Shirakashi, Ryo A1 - Sisario, Dmitri A1 - Taban, Danush A1 - Korsa, Tessa A1 - Wanner, Sophia B. A1 - Neubauer, Julia A1 - Djuzenova, Cholpon S. A1 - Zimmermann, Heiko A1 - Sukhorukov, Vladimir L. T1 - Contraction of the rigor actomyosin complex drives bulk hemoglobin expulsion from hemolyzing erythrocytes JF - Biomechanics and Modeling in Mechanobiology N2 - Erythrocyte ghost formation via hemolysis is a key event in the physiological clearance of senescent red blood cells (RBCs) in the spleen. The turnover rate of millions of RBCs per second necessitates a rapid efflux of hemoglobin (Hb) from RBCs by a not yet identified mechanism. Using high-speed video-microscopy of isolated RBCs, we show that electroporation-induced efflux of cytosolic ATP and other small solutes leads to transient cell shrinkage and echinocytosis, followed by osmotic swelling to the critical hemolytic volume. The onset of hemolysis coincided with a sudden self-propelled cell motion, accompanied by cell contraction and Hb-jet ejection. Our biomechanical model, which relates the Hb-jet-driven cell motion to the cytosolic pressure generation via elastic contraction of the RBC membrane, showed that the contributions of the bilayer and the bilayer-anchored spectrin cytoskeleton to the hemolytic cell motion are negligible. Consistent with the biomechanical analysis, our biochemical experiments, involving extracellular ATP and the myosin inhibitor blebbistatin, identify the low abundant non-muscle myosin 2A (NM2A) as the key contributor to the Hb-jet emission and fast hemolytic cell motion. Thus, our data reveal a rapid myosin-based mechanism of hemolysis, as opposed to a much slower diffusive Hb efflux. KW - electroporation KW - cell velocimetry KW - hemoglobin jet KW - non-muscle myosin KW - echinocytes KW - cytoskeleton Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-325107 VL - 22 IS - 2 ER - TY - JOUR A1 - Moustafa, Moataz A. M. A1 - Fouad, Eman A. A1 - Ibrahim, Emad A1 - Erdei, Anna Laura A1 - Kárpáti, Zsolt A1 - Fónagy, Adrien T1 - The comparative toxicity, biochemical and physiological impacts of chlorantraniliprole and indoxacarb on Mamestra brassicae (Lepidoptera: Noctuidae) JF - Toxics N2 - Background: The cabbage moth, Mamestra brassicae, is a polyphagous pest that attacks several crops. Here, the sublethal and lethal effects of chlorantraniliprole and indoxacarb were investigated on the developmental stages, detoxification enzymes, reproductive activity, calling behavior, peripheral physiology, and pheromone titer of M. brasssicae. Methods: To assess pesticide effects, the second instar larvae were maintained for 24 h on a semi-artificial diet containing insecticides at their LC\(_{10}\), LC\(_{30}\), and LC\(_{50}\) concentrations. Results: M. brassicae was more susceptible to chlorantraniliprole (LC\(_{50}\) = 0.35 mg/L) than indoxacarb (LC\(_{50}\) = 1.71 mg/L). A significantly increased developmental time was observed with both insecticides at all tested concentrations but decreases in pupation rate, pupal weight, and emergence were limited to the LC50 concentration. Reductions in both the total number of eggs laid per female and the egg viability were observed with both insecticides at their LC\(_{30}\) and LC\(_{50}\) concentrations. Both female calling activity and the sex pheromone (Z11-hexadecenyl acetate and hexadecenyl acetate) titer were significantly reduced by chlorantraniliprole in LC\(_{50}\) concentration. Antennal responses of female antennae to benzaldehyde and 3-octanone were significantly weaker than controls after exposure to the indoxocarb LC\(_{50}\) concentration. Significant reductions in the enzymatic activity of glutathione S-transferases, mixed-function oxidases, and carboxylesterases were observed in response to both insecticides. KW - toxicity KW - sublethal effects KW - chlorantraniliprole KW - indoxacarb KW - Mamestra brassicae Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-303931 SN - 2305-6304 VL - 11 IS - 3 ER - TY - THES A1 - Pitsch, Maximilian Jonathan T1 - Zyklisches Adenosinmonophosphat (cAMP) als Äquivalent akkumulierter neuronaler Evidenz T1 - Cyclic adenosine monophosphate (cAMP) as an equivalent of accumulated neuronal evidence N2 - Die vier Crz-Neurone des ventralen Nervensystems von Drosophila melanogaster sammeln Evidenz, wann im Rahmen eines Paarungsakts zirka 6 Minuten vergangen sind. Diese Entscheidung ist für die männliche Fliege von Bedeutung, da das Männchen vor Ablauf dieser ~6 Minuten, welche den Zeitpunkt der Ejakulation darstellen, eher das eigene Leben opfern würde, als dass es die Paarung beenden würde. Nach Ablauf der ~6 Minuten fällt die Motivation des Männchens dagegen dramatisch ab. Im Rahmen der vorliegenden Arbeit wurde zunächst mittels optogenetischer neuronaler Inhibitionsprotokolle sowie Verhaltensanalysen das Phänomen der Evidenz-akkumulation in den Crz-Neuronen genauer charakterisiert. Dabei zeigte sich, dass die akkumulierte Evidenz auch während einer elektrischen Inhibition der Crz-Neurone persistierte. Dieses Ergebnis warf die Hypothese auf, dass das Äquivalent der akkumulierten Evidenz in den Crz-Neuronen biochemischer Natur sein könnte. Es wurde daraufhin ein Hochdurchsatzscreening-Verfahren entwickelt, mittels dessen 1388 genetische Manipulationen der Crz-Neurone durchgeführt und auf eine Änderung der Evidenzakkumulation getestet wurden. Nur ~30 genetische Manipulationen zeigten eine veränderte Evidenzakkumulation, wobei die meisten dieser Manipulationen den cAMP-Signalweg betrafen. Mittels der optogenetischen Photoadenylatzyklase bPAC, einer Reihe weiterer genetischer Manipulationen des cAMP-Signalwegs sowie der ex vivo Kalzium-Bildgebung und Fluoreszenzlebensdauer-Mikroskopie konnte bestätigt werden, dass cAMP das Äquivalent der in den Crz-Neuronen spannungsabhängig akkumulierten Evidenz darstellt, wobei die Kombination dieser Methoden nahelegte, dass der Schwellenwert der Evidenzakkumulation durch die cAMP-Bindungsaffinität der regulatorischen PKA-Untereinheiten festgelegt sein könnte. Mittels genetischer Mosaikexperimente sowie bildgebenden Verfahren konnte darüber hinaus gezeigt werden, dass innerhalb des Crz-Netzwerks eine positive Rückkopplungsschleife aus rekurrenter Aktivität sowie der cAMP-Akkumulation besteht, welche, sobald die cAMP-Spiegel den Schwellenwert erreichen, zu einem netzwerkweit synchronisierten massiven Kalziumeinstrom führt, was die Abgabe des Crz-Signals an nachgeschaltete Netzwerke triggert. Dieses Phänomen könnte ein Analogon des Aktionspotenzials auf Netzwerkebene sowie auf Intervallzeitskalen darstellen und wurde als „Eruption“ bezeichnet. Genetische, optogenetische sowie Bildgebungsexperimente konnten zeigen, dass die CaMKII derartige Eruptionen durch Niedrighalten der cAMP-Spiegel unterdrückt, was den Zeitmessmechanismus des ersten beschriebenen Intervallzeitmessers CaMKII offenlegt. N2 - The four Crz neurons of the ventral nervous system of Drosophila melanogaster collect evidence about when approximately 6 minutes have elapsed during a mating act. This decision is of importance for the male fly as the male would rather sacrifice his own life than terminate mating before the expiration of these ~6 minutes, which represent the time of ejaculation. After these ~6 minutes, however, the male's motivation drops dramatically. In this dissertation, optogenetic neuronal inhibition protocols as well as behavioral analyses were used to characterize the phenomenon of evidence accumulation in the Crz neurons in more detail. This showed that the accumulated evidence persisted during electrical inhibition of the Crz neurons. This result raised the hypothesis that the equivalent of accumulated evidence in the Crz neurons might be biochemical in nature. A high-throughput-screening-assay was developed using which 1388 genetic manipulations of the Crz neurons were performed and tested for a change in evidence accumulation. Only ~30 genetic manipulations showed altered evidence accumulation, with most of these manipulations involving the cAMP pathway. Using the optogenetic photoadenylyl cyclase bPAC, a number of other genetic manipulations of the cAMP pathway, as well as ex vivo calcium imaging and fluorescence lifetime microscopy techniques, it was confirmed that cAMP represents the equivalent of accumulated evidence in the Crz neurons, and the combination of these methods suggested that the evidence accumulation threshold may be set by the cAMP-binding affinity of regulatory PKA subunits. Using genetic mosaic experiments as well as imaging techniques, it was further shown that within the Crz network there is a positive feedback loop between the recurrent activity as well as the cAMP accumulation, which, once cAMP levels reach the threshold, leads to a network-wide synchronized massive calcium influx, triggering the delivery of the Crz signal to downstream networks. This phenomenon could represent an analog of the action potential at the network level as well as at interval time scales and has been termed an "eruption." Genetic, optogenetic as well as imaging experiments could show that CaMKII suppresses such eruptions by keeping cAMP levels low, revealing the timing mechanism of CaMKII, the first described interval timer. KW - Evidenz KW - Drosophila KW - Biologische Uhr KW - cAMP KW - Intervallzeitmessung Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-351292 ER - TY - JOUR A1 - Römer, Daniela A1 - Aguilar, Gonzalo Pacheco A1 - Meyer, Annika A1 - Roces, Flavio T1 - Symbiont demand guides resource supply: leaf-cutting ants preferentially deliver their harvested fragments to undernourished fungus gardens JF - The Science of Nature N2 - Leaf-cutting ants are highly successful herbivores in the Neotropics. They forage large amounts of fresh plant material to nourish a symbiotic fungus that sustains the colony. It is unknown how workers organize the intra-nest distribution of resources, and whether they respond to increasing demands in some fungus gardens by adjusting the amount of delivered resources accordingly. In laboratory experiments, we analyzed the spatial distribution of collected leaf fragments among nest chambers in Acromyrmex ambiguus leaf-cutting ants, and how it changed when one of the fungus gardens experienced undernourishment. Plant fragments were evenly distributed among nest chambers when the fungal symbiont was well nourished. That pattern changed when one of the fungus gardens was undernourished and had a higher leaf demand, resulting in more leaf discs delivered to the undernourished fungus garden over at least 2 days after deprivation. Some ants bypassed nourished gardens to directly deliver their resource to the chamber with higher nutritional demand. We hypothesize that cues arising from that chamber might be used for orientation and/or that informed individuals, presumably stemming from the undernourished chamber, may preferentially orient to them. KW - insect-fungus symbiosis KW - nutrition KW - pheromone trail KW - local cues KW - decision-making KW - decentralized control Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-325080 VL - 109 IS - 3 ER - TY - THES A1 - Bakari Soale, Majeed T1 - Regulation of the Variant Surface Glycoprotein (VSG) Expression and Characterisation of the Nucleolar DExD/H box Protein Hel66 in \(Trypanosoma\) \(brucei\) T1 - Regulation der Expression des variable Oberflächen- Glykoprotein (VSG) und Charakterisierung des nukleolären DExD/H box Protein Hel66 in \(Trypanosoma\) \(brucei\) N2 - The variant surface glycoprotein (VSG) of African trypanosomes plays an essential role in protecting the parasites from host immune factors. These trypanosomes undergo antigenic variation resulting in the expression of a single VSG isoform out of a repertoire of around 2000 genes. The molecular mechanism central to the expression and regulation of the VSG is however not fully understood. Gene expression in trypanosomes is unusual due to the absence of typical RNA polymerase II promoters and the polycistronic transcription of genes. The regulation of gene expression is therefore mainly post-transcriptional. Regulatory sequences, mostly present in the 3´ UTRs, often serve as key elements in the modulation of the levels of individual mRNAs. In T. brucei VSG genes, a 100 % conserved 16mer motif within the 3´ UTR has been shown to modulate the stability of VSG transcripts and hence their expression. As a stability-associated sequence element, the absence of nucleotide substitutions in the motif is however unusual. It was therefore hypothesised that the motif is involved in other essential roles/processes besides stability of the VSG transcripts. In this study, it was demonstrated that the 100 % conservation of the 16mer motif is not essential for cell viability or for the maintenance of functional VSG protein levels. It was further shown that the intact motif in the active VSG 3´ UTR is neither required to promote VSG silencing during switching nor is it needed during differentiation from bloodstream forms to procyclic forms. Crosstalk between the VSG and procyclin genes during differentiation to the insect vector stage is also unaffected in cells with a mutated 16mer motif. Ectopic overexpression of a second VSG however requires the intact motif to trigger silencing and exchange of the active VSG, suggesting a role for the motif in transcriptional VSG switching. The 16mer motif therefore plays a dual role in VSG in situ switching and stability of VSG transcripts. The additional role of the 16mer in the essential process of antigenic variation appears to be the driving force for the 100 % conservation of this RNA motif. A screen aimed at identifying candidate RNA-binding proteins interacting with the 16mer motif, led to the identification of a DExD/H box protein, Hel66. Although the protein did not appear to have a direct link to the 16mer regulation of VSG expression, the DExD/H family of proteins are important players in the process of ribosome biogenesis. This process is relatively understudied in trypanosomes and so this candidate was singled out for detailed characterisation, given that the 16mer story had reached a natural end point. Ribosome biogenesis is a major cellular process in eukaryotes involving ribosomal RNA, ribosomal proteins and several non-ribosomal trans-acting protein factors. The DExD/H box proteins are the most important trans-acting protein factors involved in the biosynthesis of ribosomes. Several DExD/H box proteins have been directly implicated in this process in yeast. In trypanosomes, very few of this family of proteins have been characterised and therefore little is known about the specific roles they play in RNA metabolism. Here, it was shown that Hel66 is involved in rRNA processing during ribosome biogenesis. Hel66 localises to the nucleolus and depleting the protein led to a severe growth defect. Loss of the protein also resulted in a reduced rate of global translation and accumulation of rRNA processing intermediates of both the small and large ribosomal subunits. Hel66 is therefore an essential nucleolar DExD/H protein involved in rRNA processing during ribosome biogenesis. As very few protein factors involved in the processing of rRNAs have been described in trypanosomes, this finding represents an important platform for future investigation of this topic. N2 - Das variable Oberflächen-Glykoprotein (“varaint surface glycoprotein“, VSG) der Afrikanischen Trypanosomen schützt den Parasiten vor Immunfaktoren des Wirtes. Trypanosomen beherrschen die antigene Variation und expremieren nur eine einzige VSG Isoform aus einem Repertoire von ungefähr 2000 Genen. Der molekulare Mechanismus der die Expression dieser VSG Gene reguliert ist nicht komplett bekannt. Die Genexpression ist in Trypanosomen sehr ungewöhnlich. Es gibt keine typischen Promotoren für RNA Polymerase II und Gene werden polycistronisch transkribiert. Daher ist die Regulation der Genexpression hauptsächlich posttranskriptional. Die Expression individueller mRNAs wird durch regulatorische Sequenzen reguliert, die sich häufig in den 3´ UTRs befinden. In den VSG Genen von T. brucei moduliert ein zu 100% konserviertes 16mer Motiv in der 3´ UTR die Stabilität der VSG Transkripte und damit deren Expression. Für eine Sequenz, die die Stabilität der mRNA reguliert, ist das Fehlen von Nukleotid Substitutionen sehr ungewöhnlich. Es wurde deshalb spekuliert, dass das 16mer Motiv neben der Stabilisierung des VSG Transkriptes noch an anderen essentiellen Prozessen beteiligt ist. In dieser Arbeit wurde gezeigt, dass die 100%ige Konservierung des 16mer Motives weder für das Überleben der Zellen, noch für den Erhalt der Expression des VSG Protein in funktioneller Menge notwendig ist. Außerdem wurde gezeigt dass das intakte Motiv in der 3´UTR des aktiven VSGs weder für das „VSG silencing“ während des VSG Austausches („switching“) noch für die Differenzierung von Blutbahnformen zu prozyklischen Formen benötigt wird. Auch die Interaktionen („crosstalk“), die während der Differenzierung zum Insekten Stadium zwischen den VSG und Prozyklin Genen stattfinden, sind in Zellen mit mutiertem 16mer Motiv noch funktionell. Die ektopische Überexpression eines zweiten VSGs benötigt allerdings das intakte Motiv, um das aktive VSG zu inaktivieren und auszutauschen: dies suggeriert eine Rolle des Motivs im transkriptionalen „VSG switching“. Das 16mer Motif spielt daher eine Doppelrolle bei der Regulation der Stabilität der VSG Transkripte und im VSG in situ „switching“. Letzteres, die Rolle im essentiellen Prozess der antigenen Variation, ist dabei offensichtlich die treibende Kraft hinter der 100%igen Konservierung des RNA Motives. Eine Suche nach möglichen RNA bindenden Proteinen, die mit dem 16mer interagieren, führte zur Identifikation des DExD/H box Proteins Hel66. Obwohl das Protein wohl nicht direkt an der Regulation der VSG Expression über das 16mer beteiligt ist, spielen Mitglieder der DexD/H Proteinfamilie eine wichtige Rolle in der Biogenese von Ribosomen. Dieser Prozess ist in Trypanosomen noch nicht komplett verstanden und daher wurde das Protein für eine nähere Analyse ausgewählt, auch weil die 16mer Story ohne weitere Kandidaten zu einem Ende gekommen war. Die Biogenese von Ribosomen ist ein wichtiger zellulärer Prozess in Eukaryoten und benötigt ribosomale RNA, ribosomale Proteine sowie einige nicht-ribosomale, trans-agierende Protein Faktoren. Proteine der DExD/H box Familie sind die wichtigsten trans- agierenden Proteinfaktoren, die an der Biogenese der Ribosomen beteiligt sind. In der Hefe sind mehrere DExD/H box Proteine bekannt, die eine direkte Rolle in diesem Prozess spielen. In Trypanosomen sind erst sehr wenige Proteine aus dieser Familie untersucht worden und es ist daher kaum bekannt, welche spezifische Rollen sie im RNA Metabolismus spielen. In dieser Arbeit wurde gezeigt, dass Hel66 an der rRNA Prozessierung während der Biogenese der Ribosomen beteiligt ist. Hel66 ist im Nukleolus lokalisiert und die Reduktion des Proteins durch RNAi führte zu einem schweren Wachstumsphänotyp. Reduktion von Hel66 führte auch zu einer globalen Reduktion der Translation sowie zur Akkumulation von Synthese- Zwischenstadien der rRNAs sowohl der kleinen und als auch der großen ribosomalen Untereinheit. Hel66 ist daher ein essentielles nukleoläres DExD/H Protein dass an der Prozessierung der rRNA während der Biogenese der Ribosomen beteiligt ist. Da bisher erst wenige Proteine bekannt sind, die in Trypanosomen an diesem Prozess beteiligt sind, sind diese Ergebnisse ein sehr wichtiger Ausgangspunkt für weitere Untersuchungen in der Zukunft. KW - Trypanosoma brucei KW - Genexpression KW - Variant Surface Glycoprotein KW - VSG KW - DExD/H box protein KW - Ribosome biogenesis KW - rRNA processing KW - Ribosome Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-258090 ER - TY - JOUR A1 - Maloukh, Lina A1 - Nazzal, Yousef A1 - Kumarappan, Alagappan A1 - Howari, Fares A1 - Ambika, Lakshmi Kesari A1 - Yahmadi, Rihab A1 - Sharma, Manish A1 - Iqbal, Jibran A1 - Al-Taani, Ahmed A. A1 - Salem, Imen Ben A1 - Xavier, Cijo M. A1 - Naseem, Muhamad T1 - Metagenomic analysis of the outdoor dust microbiomes: a case study from Abu Dhabi, UAE JF - Atmosphere N2 - Outdoor dust covers a shattered range of microbial agents from land over transportation, human microbial flora, which includes pathogen and commensals, and airborne from the environment. Dust aerosols are rich in bacterial communities that have a major impact on human health and living environments. In this study, outdoor samples from roadside barricades, safety walls, and fences (18 samples) were collected from Abu Dhabi, UAE and bacterial diversity was assessed through a 16S rRNA amplicon next generation sequencing approach. Clean data from HiSeq produced 1,099,892 total reads pairs for 18 samples. For all samples, taxonomic classifications were assigned to the OTUs (operational taxonomic units) representative sequence using the Ribosomal Database Project database. Analysis such as alpha diversity, beta diversity, differential species analysis, and species relative abundance were performed in the clustering of samples and a functional profile heat map was obtained from the OTUs by using bioinformatics tools. A total of 2814 OTUs were identified from those samples with a coverage of more than 99%. In the phylum, all 18 samples had most of the bacterial groups such as Actinobacteria, Proteobacteria, Firmicutes, and Bacteroidetes. Twelve samples had Propionibacteria acnes and were mainly found in RD16 and RD3. Major bacteria species such as Propionibacteria acnes, Bacillus persicus, and Staphylococcus captis were found in all samples. Most of the samples had Streptococcus mitis, Staphylococcus capitis. and Nafulsella turpanensis and Enhydrobacter aerosaccus was part of the normal microbes of the skin. Salinimicrobium sp., Bacillus alkalisediminis, and Bacillus persicus are halophilic bacteria found in sediments. The heat map clustered the samples and species in vertical and horizontal classification, which represents the relationship between the samples and bacterial diversity. The heat map for the functional profile had high properties of amino acids, carbohydrate, and cofactor and vitamin metabolisms of all bacterial species from all samples. Taken together, our analyses are very relevant from the perspective of out-door air quality, airborne diseases, and epidemics, with broader implications for health safety and monitoring. KW - dust microbiomes KW - metagenomics KW - microbial diversity KW - pollution KW - GIS Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-304391 SN - 2073-4433 VL - 14 IS - 2 ER - TY - THES A1 - Maier [verh. Hartmann], Carina Ramona T1 - Regulation of the Mevalonate Pathway by the Deubiquitinase USP28 in Squamous Cancer T1 - Regulation des Mevalonat Stoffwechselwegs durch die Deubiquitinase USP28 in Plattenepithelkarzinomen N2 - The reprogramming of metabolic pathways is a hallmark of cancer: Tumour cells are dependent on the supply with metabolites and building blocks to fulfil their increased need as highly proliferating cells. Especially de novo synthesis pathways are upregulated when the cells of the growing tumours are not able to satisfy the required metabolic levels by uptake from the environment. De novo synthesis pathways are often under the control of master transcription factors which regulate the gene expression of enzymes involved in the synthesis process. The master regulators for de novo fatty acid synthesis and cholesterogenesis are sterol regulatory element-binding proteins (SREBPs). While SREBP1 preferably controls the expression of enzymes involved in fatty acid synthesis, SREBP2 regulates the transcription of the enzymes of the mevalonate pathway and downstream processes namely cholesterol, isoprenoids and building blocks for ubiquinone synthesis. SREBP activity is tightly regulated at different levels: The post-translational modification by ubiquitination decreases the stability of active SREBPs. The attachment of K48-linked ubiquitin chains marks the transcription factors for the proteasomal degradation. In tumour cells, high levels of active SREBPs are essential for the upregulation of the respective metabolic pathways. The increased stability and activity of SREBPs were investigated in this thesis. SREBPs are ubiquitinated by the E3 ligase Fbw7 which leads to the subsequential proteolysis of the transcription factors. The work conducted in this thesis identified the counteracting deubiquitination enzyme USP28 which removes the ubiquitin chains from SREBPs and prevents their proteasomal degradation. It further revealed that the stabilization of SREBP2 by USP28 plays an important role in the context of squamous cancers. Increased USP28 levels are associated with a poor survival in patients with squamous tumour subtypes. It was shown that reduced USP28 levels in cell lines and in vivo result in a decrease of SREBP2 activity and downregulation of the mevalonate pathway. This manipulation led to reduced proliferation and tumour growth. A direct comparison of adenocarcinomas and squamous cell carcinomas in lung cancer patients revealed an upregulation of USP28 as well as SREBP2 and its target genes. Targeting the USP28-SREBP2 regulatory axis in squamous cell lines by inhibitors also reduced cell viability and proliferation. In conclusion, this study reports evidence for the importance of the mevalonate pathway regulated by the USP28-SREBP2 axis in tumour initiation and progression of squamous cancer. The combinatorial inhibitor treatment of USP28 and HMGCR, the rate limiting enzyme of the mevalonate pathway, by statins opens the possibility for a targeted therapeutic treatment of squamous cancer patients. N2 - Die Reprogrammierung metabolischer Stoffwechselwege ist ein Kennzeichen von Krebs: Tumorzellen sind abhängig von der Versorgung mit Metaboliten und Bausteinen, um ihren wachsenden Bedarf als hoch proliferierende Zellen zu decken. Vor allem die de novo Stoffwechselsynthesewege sich hochreguliert, wenn die Zellen des wachsenden Tumors nicht mehr in der Lage sind, ihr erforderliches metabolisches Niveau mithilfe der Aufnahme aus der Umgebung zu erfüllen. De novo Synthesewege sind oft unter der Kontrolle von zentralen Transkriptionsfaktoren die die Genexpression von Enzymen, die im Syntheseprozess beteiligt sind, regulieren. Die vorherrschenden Regulatoren, für die de novo Fettsäuresynthese und der Cholesterogenese sind die Steroid-regulatorisches-Element-bindende Proteine (SREBPs). Während SREBP1 bevorzugt die Expression von Enzymen die an der Fettsäuresynthese beteiligt sind kontrolliert, reguliert SREBP2 die Transkription von Enzymen des Mevalonat Stoffwechselwegs, sowie Prozesse unterhalb, namentlich die Cholesterol-, Isoprenoid- und die die Synthese von Bausteinen für die Ubiquinonsynthese. Die Aktivität von SREBP ist streng reguliert auf verschiedenen Ebenen: Die post-translationale Modifikation mittels Ubiquitinierung reduziert die Stabilität von aktiven SREBPs. Das Anhängen von K48-verlinkten Ubiquitinketten markiert die Transkriptionsfaktoren für den proteasomalen Abbau. In Tumorzellen sind hohe Niveaus von aktiven SREBPs essentiell für die Induktion der entsprechenden metabolischen Stoffwechselwege. Die erhöhte Stabilität und Aktivität von SREBPs wurden im Rahmen dieser Arbeit untersucht. SREBPs werden von der E3-Ligase Fbw7 ubiquitiniert, was zur Proteolyse der Transkriptionsfaktoren führt. In dieser Arbeit wurde gezeigt, dass das entgegenwirkende Deubiquitinierungsenzym USP28 die Ubiquitinketten von SREBPs entfernt und deren proteasomalen Abbau verhindert. Diese Forschungsarbeit zeigt weiterhin, dass die Stabilisierung von SREBP2 durch USP28 eine wichtige Rolle im Kontext von Epithelkarzinomen spielt. Erhöhte USP28 Niveaus werden mit einem schlechten Überleben von Patienten in der Krebs-Untergruppe der Plattenepithelkarzinomen verbunden. Es konnte gezeigt werden, dass reduzierte USP28 Niveaus, in Zelllinien und in vivo, niedrigere SREBP2-Aktivität und eine Herunterregulierung des Mevalonat Stoffwechselwegs ergeben. Diese Manipulation führte zu reduzierter Proliferation und Tumorwachstum. Ein direkter Vergleich von Adenokarzinomen und Plattenepithelkarzinomen in Lungenkrebspatienten zeigte zudem eine Hochregulierung von USP28 ebenso wie SREBP2 und dessen Zielgenen. Der gezielte Einsatz von Inhibitoren gegen die USP28-SREBP2 regulatorische Achse in Plattenepithelzellen reduzierte die Lebensfähigkeit und Proliferation der Zellen. Abschließend berichtet diese Forschungsarbeit von der Bedeutung des durch die USP28-SREBP2 Achse regulierten Mevalonat Stoffwechselwegs bei der Tumorinitiation und dem Fortschreiten von Plattenepithelkarzinomen. Die kombinatorische Behandlung mit USP28- und Inhibitoren der HMGCR, dem Schlüsselenzym des Mevalonat Stoffwechselwegs, mithilfe von Statinen eröffnet die Möglichkeit für eine gezielte therapeutische Behandlung von Patienten mit Plattenepithelkarzinomen. KW - Ubiquitin KW - Metabolismus KW - Deubiquitination KW - Mevalonate Pathway KW - Cancer Metabolism KW - Lung squamous cancer cells Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-348740 ER - TY - JOUR A1 - Dhillon, Maninder Singh A1 - Kübert-Flock, Carina A1 - Dahms, Thorsten A1 - Rummler, Thomas A1 - Arnault, Joel A1 - Steffan-Dewenter, Ingolf A1 - Ullmann, Tobias T1 - Evaluation of MODIS, Landsat 8 and Sentinel-2 data for accurate crop yield predictions: a case study using STARFM NDVI in Bavaria, Germany JF - Remote Sensing N2 - The increasing availability and variety of global satellite products and the rapid development of new algorithms has provided great potential to generate a new level of data with different spatial, temporal, and spectral resolutions. However, the ability of these synthetic spatiotemporal datasets to accurately map and monitor our planet on a field or regional scale remains underexplored. This study aimed to support future research efforts in estimating crop yields by identifying the optimal spatial (10 m, 30 m, or 250 m) and temporal (8 or 16 days) resolutions on a regional scale. The current study explored and discussed the suitability of four different synthetic (Landsat (L)-MOD13Q1 (30 m, 8 and 16 days) and Sentinel-2 (S)-MOD13Q1 (10 m, 8 and 16 days)) and two real (MOD13Q1 (250 m, 8 and 16 days)) NDVI products combined separately to two widely used crop growth models (CGMs) (World Food Studies (WOFOST), and the semi-empiric Light Use Efficiency approach (LUE)) for winter wheat (WW) and oil seed rape (OSR) yield forecasts in Bavaria (70,550 km\(^2\)) for the year 2019. For WW and OSR, the synthetic products’ high spatial and temporal resolution resulted in higher yield accuracies using LUE and WOFOST. The observations of high temporal resolution (8-day) products of both S-MOD13Q1 and L-MOD13Q1 played a significant role in accurately measuring the yield of WW and OSR. For example, L- and S-MOD13Q1 resulted in an R\(^2\) = 0.82 and 0.85, RMSE = 5.46 and 5.01 dt/ha for WW, R\(^2\) = 0.89 and 0.82, and RMSE = 2.23 and 2.11 dt/ha for OSR using the LUE model, respectively. Similarly, for the 8- and 16-day products, the simple LUE model (R\(^2\) = 0.77 and relative RMSE (RRMSE) = 8.17%) required fewer input parameters to simulate crop yield and was highly accurate, reliable, and more precise than the complex WOFOST model (R\(^2\) = 0.66 and RRMSE = 11.35%) with higher input parameters. Conclusively, both S-MOD13Q1 and L-MOD13Q1, in combination with LUE, were more prominent for predicting crop yields on a regional scale than the 16-day products; however, L-MOD13Q1 was advantageous for generating and exploring the long-term yield time series due to the availability of Landsat data since 1982, with a maximum resolution of 30 m. In addition, this study recommended the further use of its findings for implementing and validating the long-term crop yield time series in different regions of the world. KW - MODIS KW - Sentinel-2 KW - Landsat 8 KW - sustainable agriculture KW - decision-making KW - winter wheat KW - oil seed rape KW - resolution Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-311132 SN - 2072-4292 VL - 15 IS - 7 ER - TY - JOUR A1 - Dhillon, Maninder Singh A1 - Dahms, Thorsten A1 - Kübert-Flock, Carina A1 - Liepa, Adomas A1 - Rummler, Thomas A1 - Arnault, Joel A1 - Steffan-Dewenter, Ingolf A1 - Ullmann, Tobias T1 - Impact of STARFM on crop yield predictions: fusing MODIS with Landsat 5, 7, and 8 NDVIs in Bavaria Germany JF - Remote Sensing N2 - Rapid and accurate yield estimates at both field and regional levels remain the goal of sustainable agriculture and food security. Hereby, the identification of consistent and reliable methodologies providing accurate yield predictions is one of the hot topics in agricultural research. This study investigated the relationship of spatiotemporal fusion modelling using STRAFM on crop yield prediction for winter wheat (WW) and oil-seed rape (OSR) using a semi-empirical light use efficiency (LUE) model for the Free State of Bavaria (70,550 km\(^2\)), Germany, from 2001 to 2019. A synthetic normalised difference vegetation index (NDVI) time series was generated and validated by fusing the high spatial resolution (30 m, 16 days) Landsat 5 Thematic Mapper (TM) (2001 to 2012), Landsat 7 Enhanced Thematic Mapper Plus (ETM+) (2012), and Landsat 8 Operational Land Imager (OLI) (2013 to 2019) with the coarse resolution of MOD13Q1 (250 m, 16 days) from 2001 to 2019. Except for some temporal periods (i.e., 2001, 2002, and 2012), the study obtained an R\(^2\) of more than 0.65 and a RMSE of less than 0.11, which proves that the Landsat 8 OLI fused products are of higher accuracy than the Landsat 5 TM products. Moreover, the accuracies of the NDVI fusion data have been found to correlate with the total number of available Landsat scenes every year (N), with a correlation coefficient (R) of +0.83 (between R\(^2\) of yearly synthetic NDVIs and N) and −0.84 (between RMSEs and N). For crop yield prediction, the synthetic NDVI time series and climate elements (such as minimum temperature, maximum temperature, relative humidity, evaporation, transpiration, and solar radiation) are inputted to the LUE model, resulting in an average R\(^2\) of 0.75 (WW) and 0.73 (OSR), and RMSEs of 4.33 dt/ha and 2.19 dt/ha. The yield prediction results prove the consistency and stability of the LUE model for yield estimation. Using the LUE model, accurate crop yield predictions were obtained for WW (R\(^2\) = 0.88) and OSR (R\(^2\) = 0.74). Lastly, the study observed a high positive correlation of R = 0.81 and R = 0.77 between the yearly R\(^2\) of synthetic accuracy and modelled yield accuracy for WW and OSR, respectively. KW - MOD13Q1 KW - precision agriculture KW - fusion KW - sustainable agriculture KW - decision making KW - winter wheat KW - oil-seed rape KW - crop models Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-311092 SN - 2072-4292 VL - 15 IS - 6 ER -