@article{BemmBeckerLarischetal.2016,
  author    = {Bemm, Felix and Becker, Dirk and Larisch, Christina and Kreuzer, Ines and Escalante-Perez, Maria and Schulze, Waltraud X. and Ankenbrand, Markus and Van de Weyer, Anna-Lena and Krol, Elzbieta and Al-Rasheid, Khaled A. and Mith{\"o}fer, Axel and Weber, Andreas P. and Schultz, J{\"o}rg and Hedrich, Rainer},
  title     = {Venus flytrap carnivorous lifestyle builds on herbivore defense strategies},
  series = {Genome Research},
  volume    = {26},
  journal   = {Genome Research},
  number    = {6},
  doi       = {10.1101/gr.202200.115},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-188799},
  pages     = {812-825},
  year      = {2016},
  abstract  = {Although the concept of botanical carnivory has been known since Darwin's time, the molecular mechanisms that allow animal feeding remain unknown, primarily due to a complete lack of genomic information. Here, we show that the transcriptomic landscape of the Dionaea trap is dramatically shifted toward signal transduction and nutrient transport upon insect feeding, with touch hormone signaling and protein secretion prevailing. At the same time, a massive induction of general defense responses is accompanied by the repression of cell death-related genes/processes. We hypothesize that the carnivory syndrome of Dionaea evolved by exaptation of ancient defense pathways, replacing cell death with nutrient acquisition.},
  language  = {en}
}
@article{KaltdorfSchulzeHelmprobstetal.2017,
  author    = {Kaltdorf, Kristin Verena and Schulze, Katja and Helmprobst, Frederik and Kollmannsberger, Philip and Dandekar, Thomas and Stigloher, Christian},
  title     = {Fiji macro 3D ART VeSElecT: 3D automated reconstruction tool for vesicle structures of electron tomograms},
  series = {PLoS Computational Biology},
  volume    = {13},
  journal   = {PLoS Computational Biology},
  number    = {1},
  doi       = {10.1371/journal.pcbi.1005317},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172112},
  year      = {2017},
  abstract  = {Automatic image reconstruction is critical to cope with steadily increasing data from advanced microscopy. We describe here the Fiji macro 3D ART VeSElecT which we developed to study synaptic vesicles in electron tomograms. We apply this tool to quantify vesicle properties (i) in embryonic Danio rerio 4 and 8 days past fertilization (dpf) and (ii) to compare Caenorhabditis elegans N2 neuromuscular junctions (NMJ) wild-type and its septin mutant (unc-59(e261)). We demonstrate development-specific and mutant-specific changes in synaptic vesicle pools in both models. We confirm the functionality of our macro by applying our 3D ART VeSElecT on zebrafish NMJ showing smaller vesicles in 8 dpf embryos then 4 dpf, which was validated by manual reconstruction of the vesicle pool. Furthermore, we analyze the impact of C. elegans septin mutant unc-59(e261) on vesicle pool formation and vesicle size. Automated vesicle registration and characterization was implemented in Fiji as two macros (registration and measurement). This flexible arrangement allows in particular reducing false positives by an optional manual revision step. Preprocessing and contrast enhancement work on image-stacks of 1nm/pixel in x and y direction. Semi-automated cell selection was integrated. 3D ART VeSElecT removes interfering components, detects vesicles by 3D segmentation and calculates vesicle volume and diameter (spherical approximation, inner/outer diameter). Results are collected in color using the RoiManager plugin including the possibility of manual removal of non-matching confounder vesicles. Detailed evaluation considered performance (detected vesicles) and specificity (true vesicles) as well as precision and recall. We furthermore show gain in segmentation and morphological filtering compared to learning based methods and a large time gain compared to manual segmentation. 3D ART VeSElecT shows small error rates and its speed gain can be up to 68 times faster in comparison to manual annotation. Both automatic and semi-automatic modes are explained including a tutorial.},
  language  = {en}
}
@article{NaglerNaegeleGillietal.2018,
  author    = {Nagler, Matthias and N{\"a}gele, Thomas and Gilli, Christian and Fragner, Lena and Korte, Arthur and Platzer, Alexander and Farlow, Ashley and Nordborg, Magnus and Weckwerth, Wolfram},
  title     = {Eco-Metabolomics and Metabolic Modeling: Making the Leap From Model Systems in the Lab to Native Populations in the Field},
  series = {Frontiers in Plant Science},
  volume    = {9},
  journal   = {Frontiers in Plant Science},
  number    = {1556},
  issn      = {1664-462X},
  doi       = {10.3389/fpls.2018.01556},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-189560},
  year      = {2018},
  abstract  = {Experimental high-throughput analysis of molecular networks is a central approach to characterize the adaptation of plant metabolism to the environment. However, recent studies have demonstrated that it is hardly possible to predict in situ metabolic phenotypes from experiments under controlled conditions, such as growth chambers or greenhouses. This is particularly due to the high molecular variance of in situ samples induced by environmental fluctuations. An approach of functional metabolome interpretation of field samples would be desirable in order to be able to identify and trace back the impact of environmental changes on plant metabolism. To test the applicability of metabolomics studies for a characterization of plant populations in the field, we have identified and analyzed in situ samples of nearby grown natural populations of Arabidopsis thaliana in Austria. A. thaliana is the primary molecular biological model system in plant biology with one of the best functionally annotated genomes representing a reference system for all other plant genome projects. The genomes of these novel natural populations were sequenced and phylogenetically compared to a comprehensive genome database of A. thaliana ecotypes. Experimental results on primary and secondary metabolite profiling and genotypic variation were functionally integrated by a data mining strategy, which combines statistical output of metabolomics data with genome-derived biochemical pathway reconstruction and metabolic modeling. Correlations of biochemical model predictions and population-specific genetic variation indicated varying strategies of metabolic regulation on a population level which enabled the direct comparison, differentiation, and prediction of metabolic adaptation of the same species to different habitats. These differences were most pronounced at organic and amino acid metabolism as well as at the interface of primary and secondary metabolism and allowed for the direct classification of population-specific metabolic phenotypes within geographically contiguous sampling sites.},
  language  = {en}
}
@article{BakhtiarizadehHosseinpourShahhoseinietal.2018,
  author    = {Bakhtiarizadeh, Mohammad Reza and Hosseinpour, Batool and Shahhoseini, Maryam and Korte, Arthur and Gifani, Peyman},
  title     = {Weighted gene co-expression network analysis of endometriosis and identification of functional modules associated with its main hallmarks},
  series = {Frontiers in Genetics},
  volume    = {9},
  journal   = {Frontiers in Genetics},
  number    = {453},
  doi       = {10.3389/fgene.2018.00453},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177376},
  year      = {2018},
  abstract  = {Although many genes have been identified using high throughput technologies in endometriosis (ES), only a small number of individual genes have been analyzed functionally. This is due to the complexity of the disease that has different stages and is affected by various genetic and environmental factors. Many genes are upregulated or downregulated at each stage of the disease, thus making it difficult to identify key genes. In addition, little is known about the differences between the different stages of the disease. We assumed that the study of the identified genes in ES at a system-level can help to better understand the molecular mechanism of the disease at different stages of the development. We used publicly available microarray data containing archived endometrial samples from women with minimal/mild endometriosis (MMES), mild/severe endometriosis (MSES) and without endometriosis. Using weighted gene co-expression analysis (WGCNA), functional modules were derived from normal endometrium (NEM) as the reference sample. Subsequently, we tested whether the topology or connectivity pattern of the modules was preserved in MMES and/or MSES. Common and specific hub genes were identified in non-preserved modules. Accordingly, hub genes were detected in the non-preserved modules at each stage. We identified sixteen co-expression modules. Of the 16 modules, nine were non-preserved in both MMES and MSES whereas five were preserved in NEM, MMES, and MSES. Importantly, two non-preserved modules were found in either MMES or MSES, highlighting differences between the two stages of the disease. Analyzing the hub genes in the non-preserved modules showed that they mostly lost or gained their centrality in NEM after developing the disease into MMES and MSES. The same scenario was observed, when the severeness of the disease switched from MMES to MSES. Interestingly, the expression analysis of the new selected gene candidates including CC2D2A, AEBP1, HOXB6, IER3, and STX18 as well as IGF-1, CYP11A1 and MMP-2 could validate such shifts between different stages. The overrepresented gene ontology (GO) terms were enriched in specific modules, such as genetic disposition, estrogen dependence, progesterone resistance and inflammation, which are known as endometriosis hallmarks. Some modules uncovered novel co-expressed gene clusters that were not previously discovered.},
  language  = {en}
}
@article{TogninalliSerenMengetal.2018,
  author    = {Togninalli, Matteo and Seren, {\"U}mit and Meng, Dazhe and Fitz, Joffrey and Nordborg, Magnus and Weigel, Detlef and Borgwardt, Karsten and Korte, Arthur and Grimm, Dominik G.},
  title     = {The AraGWAS Catalog: a curated and standardized Arabidopsis thaliana GWAS catalog},
  series = {Nucleic Acids Research},
  volume    = {46},
  journal   = {Nucleic Acids Research},
  number    = {D1},
  doi       = {10.1093/nar/gkx954},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-158727},
  pages     = {D1150-D1156},
  year      = {2018},
  abstract  = {The abundance of high-quality genotype and phenotype data for the model organism Arabidopsis thaliana enables scientists to study the genetic architecture of many complex traits at an unprecedented level of detail using genome-wide association studies (GWAS). GWAS have been a great success in A. thaliana and many SNP-trait associations have been published. With the AraGWAS Catalog (https://aragwas.1001genomes.org) we provide a publicly available, manually curated and standardized GWAS catalog for all publicly available phenotypes from the central A. thaliana phenotype repository, AraPheno. All GWAS have been recomputed on the latest imputed genotype release of the 1001 Genomes Consortium using a standardized GWAS pipeline to ensure comparability between results. The catalog includes currently 167 phenotypes and more than 222 000 SNP-trait associations with P < 10\(^{-4}\), of which 3887 are significantly associated using permutation-based thresholds. The AraGWAS Catalog can be accessed via a modern web-interface and provides various features to easily access, download and visualize the results and summary statistics across GWAS.},
  language  = {en}
}
@article{KaltdorfTheissMarkertetal.2018,
  author    = {Kaltdorf, Kristin Verena and Theiss, Maria and Markert, Sebastian Matthias and Zhen, Mei and Dandekar, Thomas and Stigloher, Christian and Kollmannsberger, Philipp},
  title     = {Automated classification of synaptic vesicles in electron tomograms of C. elegans using machine learning},
  series = {PLoS ONE},
  volume    = {13},
  journal   = {PLoS ONE},
  number    = {10},
  doi       = {10.1371/journal.pone.0205348},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-176831},
  pages     = {e0205348},
  year      = {2018},
  abstract  = {Synaptic vesicles (SVs) are a key component of neuronal signaling and fulfil different roles depending on their composition. In electron micrograms of neurites, two types of vesicles can be distinguished by morphological criteria, the classical "clear core" vesicles (CCV) and the typically larger "dense core" vesicles (DCV), with differences in electron density due to their diverse cargos. Compared to CCVs, the precise function of DCVs is less defined. DCVs are known to store neuropeptides, which function as neuronal messengers and modulators [1]. In C. elegans, they play a role in locomotion, dauer formation, egg-laying, and mechano- and chemosensation [2]. Another type of DCVs, also referred to as granulated vesicles, are known to transport Bassoon, Piccolo and further constituents of the presynaptic density in the center of the active zone (AZ), and therefore are important for synaptogenesis [3]. To better understand the role of different types of SVs, we present here a new automated approach to classify vesicles. We combine machine learning with an extension of our previously developed vesicle segmentation workflow, the ImageJ macro 3D ART VeSElecT. With that we reliably distinguish CCVs and DCVs in electron tomograms of C. elegans NMJs using image-based features. Analysis of the underlying ground truth data shows an increased fraction of DCVs as well as a higher mean distance between DCVs and AZs in dauer larvae compared to young adult hermaphrodites. Our machine learning based tools are adaptable and can be applied to study properties of different synaptic vesicle pools in electron tomograms of diverse model organisms.},
  language  = {en}
}
@article{FigueiredoKraussSteffanDewenteretal.2019,
  author    = {Figueiredo, Ludmilla and Krauss, Jochen and Steffan-Dewenter, Ingolf and Cabral, Juliano Sarmento},
  title     = {Understanding extinction debts: spatio-temporal scales, mechanisms and a roadmap for future research},
  series = {Ecography},
  volume    = {42},
  journal   = {Ecography},
  number    = {12},
  doi       = {10.1111/ecog.04740},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204859},
  pages     = {1973-1990},
  year      = {2019},
  abstract  = {Extinction debt refers to delayed species extinctions expected as a consequence of ecosystem perturbation. Quantifying such extinctions and investigating long-term consequences of perturbations has proven challenging, because perturbations are not isolated and occur across various spatial and temporal scales, from local habitat losses to global warming. Additionally, the relative importance of eco-evolutionary processes varies across scales, because levels of ecological organization, i.e. individuals, (meta)populations and (meta)communities, respond hierarchically to perturbations. To summarize our current knowledge of the scales and mechanisms influencing extinction debts, we reviewed recent empirical, theoretical and methodological studies addressing either the spatio-temporal scales of extinction debts or the eco-evolutionary mechanisms delaying extinctions. Extinction debts were detected across a range of ecosystems and taxonomic groups, with estimates ranging from 9 to 90\% of current species richness. The duration over which debts have been sustained varies from 5 to 570 yr, and projections of the total period required to settle a debt can extend to 1000 yr. Reported causes of delayed extinctions are 1) life-history traits that prolong individual survival, and 2) population and metapopulation dynamics that maintain populations under deteriorated conditions. Other potential factors that may extend survival time such as microevolutionary dynamics, or delayed extinctions of interaction partners, have rarely been analyzed. Therefore, we propose a roadmap for future research with three key avenues: 1) the microevolutionary dynamics of extinction processes, 2) the disjunctive loss of interacting species and 3) the impact of multiple regimes of perturbation on the payment of debts. For their ability to integrate processes occurring at different levels of ecological organization, we highlight mechanistic simulation models as tools to address these knowledge gaps and to deepen our understanding of extinction dynamics.},
  language  = {en}
}
@phdthesis{Fuellsack2019,
  author    = {F{\"u}llsack, Simone Alexandra},
  title     = {Die Bedeutung von Todesdom{\"a}ne Adapterproteinen f{\"u}r die Signaltransduktion des TNFR1 und der TRAIL Todesrezeptoren},
  doi       = {10.25972/OPUS-18451},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-184518},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {Die NFκB-Signalwege, Apoptose und Nekroptose sind essentielle Prozesse in der Immunantwort. Außerdem sind diese Signalwege Teil der Regulation von Zelldifferenzierung, -proliferation, -tod und Entz{\"u}ndungsreaktionen. Dabei wird zuerst der Rezeptor (TNFR1 oder TRAILR 1/2) aktiviert, die rekrutierten DD-Adapterproteine TRADD, FADD und RIPK1 leiten dann die entsprechende Signalkaskade weiter und bestimmen durch ihre Zusammenwirkung, ob der NFκB-Signalweg, Apoptose oder Nekroptose induziert wird. TNFR1 und TRAILR 1/2 ben{\"o}tigen die DD-Adapterproteine TRADD, FADD und RIPK1 f{\"u}r die Zelltodinduktion, deren konkrete Bedeutung in Bezug auf Rezeptor-Spezifit{\"a}t, Zusammenwirken und Relevanz allerdings noch unklar ist. Um das Zusammenspiel dieser Proteine besser zu verstehen, wurden in dieser Arbeit Nekroptose-kompetente RIPK3-exprimierende HeLa-Zellen verwendet, bei denen die DD-Adapterproteine FADD, TRADD und RIPK1 einzeln oder in Kombination von zweien ausgeknockt wurden. Es stellte sich heraus, dass RIPK1 essentiell f{\"u}r die TNFR1- und TRAILR 1/2-vermittelte Nekroptose-Induktion ist, doch RIPK1 alleine, d.h. ohne FADD- oder TRADD-Mitbeteiligung, nur bei der TNFR1-Nekroptose-Induktion ausreicht. Wiederum inhibiert TRADD die TNFR1- und TRAILR 1/2-induzierte Nekroptose. RIPK1 und TRADD sind aber unverzichtbar f{\"u}r die NFκB-Aktivierung durch TNFR1 oder TRAILR 1/2 und spielen eine wichtige Rolle bei TNFR1-induzierter Apoptose. Andererseits ist FADD alleine ausreichend f{\"u}r die TRAILR 1/2-bezogene Caspase-8 Aktivierung. Zudem ist FADD notwendig f{\"u}r die TRAIL-induzierte NFκB-Signalaktivierung. In Abwesenheit von FADD und TRADD vermittelt RIPK1 die TNF-induzierte Caspase-8 Aktivierung. FADD wird f{\"u}r die TRAIL-induzierte Nekroptose ben{\"o}tigt, aber gegenl{\"a}ufig wirkt die TNF-induzierte Nektroptose in einer Caspase-8 abh{\"a}ngigen und unabh{\"a}ngigen Weise. Zudem sensitiviert TWEAK die TNF- und TRAIL-induzierte Nekroptose. Zusammenfassend wurde in dieser Arbeit die Auswirkung von TNFR1 und TRAILR 1/2 auf die Aktivierung der unterschiedlichen Signalkaskaden untersucht. Des Weiteren wurde gezeigt, in welcher Weise sich das Zusammenspiel von TRADD, FADD und RIPK1 auf die Induktion von NFκB, Apoptose und Nekroptose auswirkt.},
  subject      = {Signaltransduktion},
  language  = {de}
}
@phdthesis{Leidinger2020,
  author    = {Leidinger, Ludwig Klaus Theodor},
  title     = {How genomic and ecological traits shape island biodiversity - insights from individual-based models},
  doi       = {10.25972/OPUS-20730},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-207300},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2020},
  abstract  = {Life on oceanic islands provides a playground and comparably easy\-/studied basis for the understanding of biodiversity in general. Island biota feature many fascinating patterns: endemic species, species radiations and species with peculiar trait syndromes. However, classic and current island biogeography theory does not yet consider all the factors necessary to explain many of these patterns. In response to this, there is currently a shift in island biogeography research to systematically consider species traits and thus gain a more functional perspective. Despite this recent development, a set of species characteristics remains largely ignored in island biogeography, namely genomic traits. Evidence suggests that genomic factors could explain many of the speciation and adaptation patterns found in nature and thus may be highly informative to explain the fascinating and iconic phenomena known for oceanic islands, including species radiations and susceptibility to biotic invasions. Unfortunately, the current lack of comprehensive meaningful data makes studying these factors challenging. Even with paleontological data and space-for-time rationales, data is bound to be incomplete due to the very environmental processes taking place on oceanic islands, such as land slides and volcanism, and lacks causal information due to the focus on correlative approaches. As promising alternative, integrative mechanistic models can explicitly consider essential underlying eco\-/evolutionary mechanisms. In fact, these models have shown to be applicable to a variety of different systems and study questions. In this thesis, I therefore examined present mechanistic island models to identify how they might be used to address some of the current open questions in island biodiversity research. Since none of the models simultaneously considered speciation and adaptation at a genomic level, I developed a new genome- and niche-explicit, individual-based model. I used this model to address three different phenomena of island biodiversity: environmental variation, insular species radiations and species invasions. Using only a single model I could show that small-bodied species with flexible genomes are successful under environmental variation, that a complex combination of dispersal abilities, reproductive strategies and genomic traits affect the occurrence of species radiations and that invasions are primarily driven by the intensity of introductions and the trait characteristics of invasive species. This highlights how the consideration of functional traits can promote the understanding of some of the understudied phenomena in island biodiversity. The results presented in this thesis exemplify the generality of integrative models which are built on first principles. Thus, by applying such models to various complex study questions, they are able to unveil multiple biodiversity dynamics and patterns. The combination of several models such as the one I developed to an eco\-/evolutionary model ensemble could further help to identify fundamental eco\-/evolutionary principles. I conclude the thesis with an outlook on how to use and extend my developed model to investigate geomorphological dynamics in archipelagos and to allow dynamic genomes, which would further increase the model's generality.},
  subject      = {Inselbiogeografie},
  language  = {en}
}
@phdthesis{Jaslan2020,
  author    = {Jaslan, Dawid Artur},
  title     = {TPC1 mutants provide insight into SV channel function},
  doi       = {10.25972/OPUS-15731},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-157312},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2020},
  abstract  = {In the framework of the presented doctoral thesis, the plant ubiquitous, non-selective vacuolar cation channel TPC1/SV was electrophysiologically studied in Arabidopsis thaliana mesophyll vacuoles to further enlighten its physiological role in plant stress responses. For this, the hyperactive channel version fou2 (D454N), gaining a non-functional vacuolar calcium sensor, strong retarded growth phenotype and upregulated JA signalling pathway, and eight fou2 reverting WT-like ouf mutants were used. Except of ouf4, all other seven ouf mutants carried a 2nd mutation in the TPC1 gene. Therefore, the TPC1 electrical features of all ouf mutants were electrophysiologically characterized with the patch clamp method and compared with fou2 and WT. Due to a missense mutation, ouf1 and ouf7 mutants harboured a truncated TPC1 channel protein, resulting in an impaired protein integrity and in turn loss of TPC1 channel activity. Accordingly, ouf1 and ouf7 mimicked the tpc1-2 null mutant with a WT- rather fou2-like phenotype. The ouf2 (G583D D454N) mutant exhibited inactive TPC1 channels, probably because the G583D mutation located in luminal part of the S11 helix caused (i) a shift of the activation threshold to much more positive voltages (i.e. to more than +110 mV) (ii) or channel blockage. As a result of the TPC1 channel inactivity, the ouf2 mutant also imitates the WT-like phenotype of the tpc1-2 null mutant. In the ouf6 mutant (A669V D454N) the 2nd reverting mutation selectively influenced fou2-like SV channel features. Both, the fast activation kinetics and reduced luminal calcium sensitivity were similar in ouf6 and fou2. However, deviations in both, the relative and absolute open channel probability, resulted in strongly reduced (80 \%) current density at 0 mM and channel inactivity in the voltage range between -30 mV to +40 mV compared to fou2 and WT. Furthermore, the TPC1 channels in ouf6 exhibited a higher susceptibility to inhibitory luminal Ca2+ than fou2. As a result of these different effects, the TPC1 channel activity almost vanished at high luminal Ca2+ loads, what is very likely the reason that ouf6 lost the fou2-like phenotype. The ouf4 mutation did not change the fou2 TPC1-channel features like fast channel activation, single channel conductance and voltage-dependent gating behaviour. Nevertheless, the TPC1 current density was 80\% less in ouf4 than in fou2. Since the TPC1 gene was not the target of the 2nd mutation, it can be assumed that it is modulated via external, yet unknown factor. In the ouf8 mutant the TPC1 channels additionally possess M629I mutation within the selectivity filter II resulting in a 50\% decrease in the TPC1 unitary conductance. However, the slightly increased relative open channel probability of the TPC1 channels in ouf8 compared to fou2 appeared to be sufficient to compensate the reduced transport capacity of individual TPC1 channels. As a result, a similar macroscopic outward current density of ouf8 and fou2 was detected in the absence of vacuolar Ca2+. Furthermore, ouf8 mutation did not drastically change the typical fou2 TPC1 channel features such as fast activation, vacuolar calcium insensitivity and voltage dependency. However, a reversible block of the cytosol-directed potassium efflux at increased vacuolar calcium concentration in ouf8 mutant was found. Further inspection of transiently expressed TPC1 channel variants (M629I, M629T) on the single channel level suggest that Met629 of AtTPC1 in the channel pore region is crucial for the unitary channel conductance. Taken together, current membrane recordings from ouf mutants revealed one common feature: All of them lacked or showed a strongly impaired ability for TPC1-mediated potassium release from the vacuole into the cytosol. Additionally, considering the detected dependence of the vacuolar membrane voltage on TPC1 activity, it thus seems that the TPC1-triggered vacuolar membrane depolarization caused by vacuolar K+ release plays a key role in generation of the fou2-like phenotype. Accordingly, one can conclude that TPC1-dependent vacuolar membrane depolarization and initiation of jasmonate production are likely linked. This statement is supported also by the complete restoration of WT-like plant phenotype and JA signalling in the ouf mutants. Finally, as a control element of the vacuolar membrane voltage TPC1 is probably upstream located in JA signalling pathway and therefore a perfect junction for linking multiple physiological stimuli and response to them. Im Rahmen der vorgelegten Doktorarbeit wurde der in Pflanzen ubiquit{\"a}r exprimierte, nicht-selektive vakuol{\"a}re Kationenkanal TPC1/SV elektrophysiologisch in Arabidopsis thaliana Mesophyllvakuolen untersucht, um seine physiologische Rolle in der pflanzlichen Stressantwort weiter aufzukl{\"a}ren. Hierf{\"u}r wurde die hyperaktive Kanalvariante fou2 (D454N), die einen nicht-funktionalen vakuol{\"a}ren Calciumsensor, ein stark verz{\"o}gertes Pflanzenwachstum und einen hochregulierten Jasmons{\"a}ure-Signalweg aufweist, sowie acht ouf Mutanten mit fou2-umkehrenden Ph{\"a}notyp benutzt. Mit Ausnahme von ouf4 enthalten alle anderen ouf Mutanten eine weitere Mutation im TPC1-Gen. Daher wurden die elektrischen Eigenschaften von TPC1 in allen ouf Mutanten elektrophysiologisch mittels der Patch clamp Technik charakterisiert und mit fou2 und dem Wildtyp verglichen. Aufgrund einer Missense-Mutation beinhalten die Mutanten ouf1 und ouf7 ein verk{\"u}rztes TPC1 Protein, woraus eine gest{\"o}rte Proteinintegrit{\"a}t resultiert und daraus wiederum ein Fehlen der TCP1-Kanalaktivit{\"a}t. Dementsprechend {\"a}hneln ouf1 und ouf7 der tpc1-2 Nullmutante mit einem WT- oder eher fou2-artigen Ph{\"a}notyp. Wahrscheinlich weist die ouf2 (G583D D454N) Mutante einen inaktiven TPC1-Kanal auf, weil die G583D Mutation, die in einem luminalen Teil der S11 Helix sitzt, eine Verschiebung der Aktivierungsschwelle hin zu einer h{\"o}heren Spannung (z. B. mehr als +110 mV) oder einen Kanalblock verursacht. Als Folge der TPC1 Kanal Inaktivit{\"a}t, ahmt die ouf2 Mutante auch den WT-{\"a}hnlichen Ph{\"a}notyp der tpc1-2 Nullmutante nach. In der ouf6 Mutante (A669V D454N) beeinflusst die zweite Mutation selektiv die fou2-{\"a}hnlichen SV-Kanaleigenschaften. Sowohl die schnelle Aktivierungskinetik als auch die verringerte luminale Calciumsensitivit{\"a}t waren denen von ouf6 und fou2 {\"a}hnlich. Die Abweichungen in der relativen sowie der absoluten Offenwahrscheinlichkeit resultierten jedoch in einer stark reduzierten (80 \%) Stromdichte bei 0 mM luminalem Calcium verglichen mit fou2 und dem WT, sowie einer Kanalinaktivit{\"a}t bei Spannungen zwischen -30 mV und +40 mV. Dar{\"u}ber hinaus zeigten die TPC1 Kan{\"a}le in ouf6 eine h{\"o}here Anf{\"a}lligkeit f{\"u}r inhibitorisches, luminales Calcium als die in fou2. Das Ergebnis der beiden unterschiedlichen Effekte ist, dass die TPC1 Kanalaktivit{\"a}t bei einer hohen luminalen Calciumkonzentration fast verschwindet, woraus zu schließen ist, dass ouf6 den fou2-{\"a}hnlichen Ph{\"a}notyp verlor. Die ouf4 Mutation ver{\"a}nderte nicht die fou2 TPC1 Kanaleigenschaften, wie die schnelle Kanalaktivierung, die Einzelkanalleitf{\"a}higkeit und das spannungsabh{\"a}ngige Verhalten. Nichtsdestotrotz war die TCP1 Stromdichte in ouf4 um 80 \% geringer als in fou2. Da das TPC1 Gen nicht das Ziel der zweiten Mutation war, kann angenommen werden, dass es durch {\"a}ußere, bisher noch unbekannte Faktoren, reguliert wird. In der ouf8 Mutante haben die TPC1 Kan{\"a}le zus{\"a}tzlich eine M629I Mutation innerhalb des zweiten Selektivit{\"a}tsfilters, welche in einem 50 \% R{\"u}ckgang der TCP1 Einzelkanalleitf{\"a}higkeit resultiert. Jedoch scheint die leicht erh{\"o}hte Offenwahrscheinlichkeit der TCP1 Kan{\"a}le in ouf8, verglichen mit fou2, ausreichend zu sein, um die reduzierte Transportkapazit{\"a}t der individuellen TPC1 Kan{\"a}le zu kompensieren. Schlussfolgernd wurde eine {\"a}hnliche makroskopische ausw{\"a}rts gerichtete Stromdichte des ouf8 und des fou2 in Abwesenheit vakuol{\"a}ren Calciums entdeckt. Des Weiteren {\"a}nderte eine ouf8 Mutation die fou2 TPC1 Kanaleigenschaften wie eine schnelle Aktivierung, vakuol{\"a}re Calciuminsensitivit{\"a}t und die Spannungsabh{\"a}ngigkeit nicht drastisch. Jedoch wurde ein reversibler Block des Zytosol-gerichteten Kalium Ausstroms bei erh{\"o}hten vakuol{\"a}ren Calcium Konzentrationen in ouf8 gefunden. Eine weitere Betrachtung transient exprimierter TPC1 Kanalvarianten (M629I, M629T) auf Einzelkanalebene weist darauf hin, dass das Met629 des AtTPC1 in der Kanalporenregion entscheidend ist f{\"u}r die Einzelkanalleitf{\"a}higkeit. Zusammengefasst zeigt der {\"u}ber die Membran von ouf Mutanten gemessene Strom eine Gemeinsamkeit: Alle zeigten keinen oder einen stark beeintr{\"a}chtigten TPC1-vermittelten Kaliumausstrom aus der Vakuole ins Zytosol. Unter Ber{\"u}cksichtigung der beobachteten Abh{\"a}ngigkeit der vakuol{\"a}ren Membranspannung von der TPC1 Aktivit{\"a}t, scheint es, als ob die durch TPC1 angeregte Depolarisation der Vakuolenmembran, welche durch die vakuol{\"a}re Kaliumfreisetzung bedingt wird, in der Ausbildung des fou2 Ph{\"a}notyps eine Rolle spielt. Daraus l{\"a}sst sich ableiten, dass die TPC1-abh{\"a}ngige Depolarisation der Vakuolenmembran und die Jasmonat Bildung vermutlich verbunden sind. Diese Behauptung wird auch gest{\"u}tzt durch die komplette Wiederherstellung des WT-{\"a}hnlichen Pflanzenph{\"a}notyps und des Jasmons{\"a}ure Signalwegs in den ouf Mutanten. Letztendlich ist TPC1 als kontrollierendes Element der vakuol{\"a}ren Membranspannung wahrscheinlich dem Jasmons{\"a}ure Signalweg vorgeschaltet und deswegen ein perfekter Knotenpunkt, der verschiedene physiologische Stimuli und ihre Antworten verbindet.},
  language  = {en}
}