@phdthesis{Hagedorn2011, author = {Hagedorn, Ina}, title = {Novel mechanisms underlying arterial thrombus formation: in vivo studies in (genetically modified) mice}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-85752}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Thrombus formation at sites of vascular lesions is a dynamic process that requires a defined series of molecular events including the action of platelet adhesion/activation receptors, intracellular signal transduction, cytoskeletal rearrangements and activation of plasma coagulation factors. This process is essential to limit post-traumatic blood loss but may also contribute to acute thrombotic diseases such as myocardial infarction and stroke. With the help of genetically modified mice and the use of specific protein inhibitors and receptordepleting antibodies, the work presented in this thesis identified novel mechanisms underlying thrombus formation in hemostasis and thrombosis. In the first part of the study, it was shown that von Willebrand Factor (vWF) binding to glycoprotein (GP)Iba is critical for the formation of stable pathological thrombi at high shear rates, suggesting GPIba as an attractive pharmacological target for antithrombotic therapy. The subsequent analysis of recently generated phospholipase (PL)D1-deficient mice identified this enzyme, whose role in platelet function had been largely unknown, as a potential target protein downstream of GPIba. This was based on the finding that PLD1- deficient mice displayed severely defective GPIba-dependent thrombus stabilization under high shear conditions in vitro and in vivo without affecting normal hemostasis. The second part of the thesis characterizes the functional relevance of the immunoreceptor tyrosine-based activation motif (ITAM)-bearing collagen receptor GPVI and the recently identified hemITAM-coupled C-type lectin-like receptor 2 (CLEC-2) for in vivo thrombus formation. Genetic- and antibody-induced GPVI deficiency was found to similarly protect mice from arterial vessel occlusion in three different thrombosis models. These results confirmed GPVI as a promising antithrombotic target and revealed that antibody-treatment had no obvious off-target effects on platelet function. Similarly, immunodepletion of CLEC-2 by treating mice with the specific antibody INU1 resulted in markedly impaired thrombus growth and stabilization under flow in vitro and in vivo. Furthermore, it could be demonstrated that double-immunodepletion of GPVI and CLEC-2 resulted in severely decreased arterial thrombus formation accompanied by dramatically prolonged bleeding times. These data revealed an unexpected redundant function of the two receptors for in vivo thrombus formation and might have important implications for the potential development of anti-GPVI and anti-CLEC-2 antithrombotic agents. The third part of the thesis provides the first functional analysis of megakaryocyte- and platelet-specific RhoA knockout mice. RhoA-deficient mice displayed a defined signaling defect in platelet activation, leading to a profound protection from arterial thrombosis andand ischemic brain infarction, but at the same time also strongly increased bleeding times. These findings identified the GTPase as an important player for thrombus formation in hemostasis and thrombosis. Based on the previous proposal that the coagulation factor (F)XII might represent an ideal target for safe antithrombotic therapy without causing bleeding side effects, the last part of this thesis assesses the antithrombotic potential of the newly generated FXIIa inhibitor rHAInfestin- 4. It was found that rHA-Infestin-4 injection into mice resulted in virtually abolished arterial thrombus formation but no change in bleeding times. Moreover, rHA-Infestin-4 was similarly efficient in a murine model of ischemic stroke, suggesting that the inhibitor might be a promising agent for effective and safe therapy of cardio- and cerebrovascular diseases.}, subject = {Thrombus}, language = {en} } @phdthesis{Gerold2011, author = {Gerold, Kay}, title = {CTLA4 and CLEC16A in Type 1 Diabetes - Looking behind the association}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-66617}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Type 1 diabetes is an autoimmune disease that leads to the destruction of insulin-producing pancreatic beta cells and consequently to hyperglycemia. In the last 60 years, the prevalence of type 1 diabetes has been increasing constantly and is predicted to continue rising. About 80\% of the disease risk is attributable to the genetic variation. Thanks to genome wide association studies the number of known disease-associated polymorphisms climbed from five to 53 in the last 10 years. As these studies reveal possible candidate genes but not underlying mechanisms we strove to take the next step and explore the association of two genes suggested by these studies with type 1 diabetes. As a method of choice we decided to use lentiviral RNAi in non obese diabetic (NOD) mice, a widely-used model for type 1 diabetes, introducing a shRNA directed against the target message into the genome of this mouse strain via a lentivirus. This allowed us to study the partial loss-of-function of the target gene within the context of diabetes, directly seeing its effect on autoimmune mechanisms. In this thesis we examined two different genes in this manner, Ctla4 and Clec16a. A type 1 diabetes associated polymorphism in the CTLA4 gene had been found to alter the splicing ratio of its variants soluble CTLA-4 (sCTLA-4) and full length CTLA-4, the associated allele producing less sCTLA-4 than the protective allele. We mimicked this effect by specifically targeting the sCtla4 mRNA via lentiviral RNAi in the NOD model. As a result we could confirm the reduction of sCTLA-4 to accelerate type 1 diabetes development. Furthermore we could show a function of sCTLA-4 in regulatory T cells, more specifically at least partly in their ability to modulate costimulation by antigen presenting cells. The second candidate gene, Clec16a was targeted with the shRNA in a way that was designed to knock down most splice variants. As the gene function and the effect of the associated SUMMARY 10 polymorphism was unknown, we reasoned this method to be feasible to investigate its role in type 1 diabetes. The knockdown of Clec16a in NOD mice resulted in an almost complete protection from diabetes development that could be attributed to T cells dysfunction. However, as expression patterns and a study of the Drospophila orthologue suggested a possible role of CLEC16A in antigen presentation we also examined antigen presenting cells in the thymus and periphery. Although we did not detect any effect of the knockdown on peripheral antigen presenting cells, thymic epithelial cells were clearly affected by the loss of CLEC16A, rendering them more activated and shifting the ratio of cortical to medullary epithelial cells in favor of cortical cells. We therefore suggest a role of CLEC16A in the selection of T cells, that needs, however, to be further investigated. In this thesis we provided a feasible and fast method to study function of genes and even of single splice variants within the NOD mouse model. We demonstrate its usefulness on two candidate genes associated with type 1 diabetes by confirming and unraveling the cause of their connection to the disease.}, subject = {Diabetes mellitus}, language = {en} } @phdthesis{Gan2011, author = {Gan, Qiang}, title = {Investigation on Distinct Roles of Smad Proteins in Mediating Bone Morphogenetic Proteins Signals}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-71127}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Knochenmorphogenetische Proteine (engl. Bone morphogenetic Proteins, BMPs) sind eine Bestandteil von transforming growth factor-β (TGF-β)-Superfamilie und spielen wichtige Rollen in zahlreichen biologischen Ereignissen in der Entwicklung fast aller mehrzelligen Organismen. Fehlregulierte BMP-Signalweg ist die zugrunde liegenden Ursachen von zahlreichen erblichen und nicht erblichen Krankheiten wie Krebs. Die von BMP induziete breite Palette von biologischen Reaktionen konvergiert auf drei eng verwandten Smad Proteine. Sie vermitteln intrazellul{\"a}re Signale von BMP-Rezeptoren in den Zellkern. Die Spezifit{\"a}t des BMP-Signalwegs wurde intensiv auf der Ebene der Ligand-Rezeptor-Wechselwirkungen erforscht, aber, wie die verschiedenen Smad Proteine die durch BMPs hervorgerufen differenziellen Signale beitragen, bleibt unklar. In dieser Arbeit haben wir die BMP / Smad Signalweg in verschiedenen Aspektenuntersucht. Auf der Suche nach einem geeigneten Fluoreszenz-Reporter im Zebrafisch, verglichen wir verschiedene photo-schaltbaren Proteine und fand EosFP der beste Kandidat f{\"u}r diesen Modellorganismus im Bezug auf seine schnelle Reifung und Fluoreszenz-Intensit{\"a}t. Wir haben durch molekulare Modifizierung geeignete Vektoren erstellt, die Tol2-Transposon basieren trangenesis im Zebrafisch zu erm{\"o}glichen. Damit wurden schließlich transgenzebrafisch-Linien erzeugt. Wir kombinierten Fluoreszenz-Protein-Tagging mit hochaufl{\"o}sender Mikroskopie und untersuchten die Dynamik der Smad-Proteine in Modellsystem Zebrafisch. Es wurde beobachteten, dass Smad5 Kern-Translokation erf{\"a}hrt, als BMP Signalgeber bei Zebrafisch Gastrulation. Wir erkundeten die Beteiligung der Smad Proteine w{\"a}hrend der Myogenese-zu-Osteogenese Umwandlung von C2C12 Zelllinie, die durch BMP4 induziert wurde. Mit siRNA versuchten wir die endogene Smad Proteine niederzuschlagen, wobei die Auswirkungen auf diesen gekoppelten noch unterschiedlichen Verfahren durch quantitative real-time PCR und Terminal-Marker F{\"a}rbung ausgewertet. Wir spekulieren, dass verschiedene Smad-Komplex St{\"o}chiometrie f{\"u}r unterschiedliche durch BMPs hervorgerufe zellul{\"a}re Signale verantwortlich sein k{\"o}nnte.}, subject = {Knochen-Morphogenese-Proteine}, language = {en} } @phdthesis{Frey2011, author = {Frey, Monika}, title = {Effects and mechanisms of a putative human pheromone}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-72292}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {There is evidence that pheromones are communicative signals in animals. However, the existence and function of human pheromones are still under discussion. During the last years several substances have been labeled as putative human pheromones and especially 4,16-androstadien-3-one (androstadienone), found in male and female sweat, became subject of intense investigation. In contrast to common odors androstadienone presumably modulates human physiological and psychological reactions. Data suggest that androstadienone might influence the processing of visual cues, specifically faces or affective stimuli, via projections from the fusiform gyrus and the amygdala. Moreover, attentional processes may be modulated, which is supported by explicit and implicit behavioral data. This thesis includes three experimental studies examining effects of androstadienone exposure on behavioral and cortical reactions to visual and emotional stimuli. The main hypotheses were that androstadienone might influence human behavior to and perception of visual cues. The first study sought to clarify androstadienone effects on attention-related reactions as well as on behavioral tendencies. Motoric approach-avoidance reactions in response to happy and angry facial expressions were investigated in 30 women and 32 men. Participants either inhaled androstadienone or a control solution, without knowing the real content, while performing the following task: they had to push away or to pull towards them a joystick as fast as possible in reaction to either an angry or a happy cartoon face, which was presented on a computer screen. Results showed that androstadienone modulated the participant´s task performance by accelerating the reaction speed compared to the control compound. Faster reactions were observed particularly when reacting to angry faces but not when reacting to happy faces. This might be explained by the finding that human body odors, the source of androstadienone, were found to activate the human fear system, i.e. modulating fear-related attentional processes. Therefore, the quicker reaction towards angry faces with exposure to androstadienone could be due to an enhanced allocation of attentional resources towards fear-related cues like angry faces. Results also showed that androstadienone enhanced men´s approach tendency towards faces independent of emotional expressions. This observation might be explained by androstadienone´s former shown ability to improve attractiveness ratings of other persons. In this regard, the endogenous odor might enhance evaluations of faces in men and, thus, might improve their willingness to approach social stimuli. In contrast to men, women already showed in the control condition higher approach tendency towards faces. Therefore, androstadienone might rather maintain than enhance the approach score in women. In the second study event-related brain potentials (ERPs) triggered by social and non-social visual stimuli were investigated by means of electroencephalography. In a double-blind between-subjects design 51 women participated. Twenty-eight women inhaled androstadienone, whereas 23 women inhaled a control solution. Four different picture categories, i.e. real faces, pictures with couples, pictures with social and non-social scenes, each including three different valence categories, i.e. positive, negative and neutral, should clarify the stimulus type or context androstadienone is acting on. The androstadienone compared to the control odor did not influence brain responses significantly. Explorative analyses, however, suggested that androstadienone influences the processing of faces. While in the control group angry faces elicited larger P300 amplitudes than happy faces, the androstadienone group showed similar P300 amplitudes concerning all emotional expressions. This observation tentatively indicates that the endogenous odor might indeed affect the neuronal responses to emotional facial stimuli, especially late components reflecting evaluative processes. However, this observation has to be verified and further investigated, in particular whether androstadienone caused reduced responses to angry faces or enhanced responses to happy faces. The third study investigated androstadienone effects on face processing especially in men. ERPs elicited by happy, angry and neutral cartoon faces, which were presented on a computer screen, were measured while 16 men, not knowing the applicated odor, inhaled either androstadienone or a control solution. Exposure to androstadienone significantly increased later neuronal responses, the P300 amplitude. This belated component of the ERP reflects attention allocation and evaluative processes towards important stimuli. Therefore, androstadienone might facilitate central nervous face processing by enhancing attention towards these stimuli. In sum, the current results corroborate the notion of androstadienone as an active social chemosignal. In minute amounts and not detectable as an odor it influenced cortical and motoric reactions. Therefore, it might be concluded that androstadienone indeed affects cognitive functions like attentional processes and in turn affects our behavior. The current results further support the notion that androstadienone acts like a human modulator pheromone, namely modulating ongoing behavior or a psychological reaction to a particular context, changing stimulus sensitivity, salience and sensory-motor integration. However, these conclusions remain tentative until further replication takes place, best in ecologically valid environments. Furthermore, one has to keep in mind that the current studies could not replicate several previous findings and could not verify some hypotheses assuming communicative effects of androstadienone. Thus, the main assumption of this thesis that androstadienone is an active chemosignal is still challenged. Also, whether the term "pheromone" is indeed suitable to label androstadienone remains open.}, subject = {Pheromon}, language = {en} } @phdthesis{Eschbach2011, author = {Eschbach, Claire}, title = {Classical and operant learning in the larvae of Drosophila melanogaster}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-70583}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {In dieser Doktorarbeit studiere ich einige psychologische Aspekte im Verhalten der Drosophila, insbesondere von Drosophila Larven. Nach einer Einleitung, in der ich den wissenschaftlichen Kontext darstelle und die Mechanismen der olfaktorischen Wahrnehmung sowie des klassichen und operanten Lernens beschreibe, stelle ich die verschiedenen Experimente meiner Doktorarbeit vor. Wahrnehmung Das zweite Kapitel behandelt die Art, in der adulte Drosophila zwischen Einzeld{\"u}ften und Duftgemischen generaliseren. Ich habe gefunden, daß die Fliegen eine Mischung aus zwei D{\"u}ften als gleich verschieden von ihren beiden Elementen wahrnehmen; und daß die Intensit{\"a}t sowie die chemisch-physikalische Natur der Elemente das Ausmass der Generalisierung zwischen der Mischung und ihren beiden Elementen beeinflusst. Diese Entdeckungen sollten f{\"u}r die weitere Forschung anregend sein, wie zum Beispiel zum functional imaging. Ged{\"a}chtnis Das dritte Kapitel stellt die Etablierung eines neuen Protokolls zur klassischen Konditionierung bei Drosophila Larven dar. Es handelt sich um Experimente, bei denen ein Duft mit einer mechanischen St{\"o}rung als Strafreiz verkn{\"u}pft wird. Das Protokoll wird einen Vergleich zwischen zwei Arten vom aversiven Ged{\"a}chtnissen (Geschmack vs. mechanische St{\"o}rung als Strafreize) erm{\"o}glichen, einschliesslich eines Vergleiches ihrer neurogenetischen Grundlagen; zudem kann nun geforscht werden, ob die jeweiligen Ged{\"a}chtnisse spezifisch f{\"u}r die Art des verwendeten Strafreizes sind. Selbstgestaltung Das vierte Kapitel umfasst unsere Versuche, operantes Ged{\"a}chtnis bei Drosophila Larven zu beobachten. Zumindest f{\"u}r die unmittelbar ersten Momente des Tests konnte ich zeigen, dass die Larven ihr Verhalten entsprechend dem Training ausrichten. Dieses Ged{\"a}chtnis scheint jedoch im Laufe des Tests schnell zu verschwinden. Es ist daher geraten, diese Ergebnisse {\"u}ber operantes Lernen zu wiederholen, eventuell das experimentelle Protokoll zu verbessern, um so eine systematische Analyse der Bedingungen und Mechanismen f{\"u}r das operante Lernen bei der Drosophila Larve zu erlauben. Im f{\"u}nften Kapitel verwende ich die im Rahmen des vierten Kapitels entwickelten Methoden f{\"u}r eine Analyse der Fortbewegung der Larven. Ich habe insbesondere die Wirkung des pflanzlichen ‚cognitive enhancers' Rhodiola rosea untersucht, sowie die Auswirkungen von Mutationen in den Genen, welche f{\"u}r Synapsin und SAP47 kodieren; schliesslich habe ich getestet, ob die Geschmacksqualit{\"a}t der Testsituation lokomotorische Parameter ver{\"a}ndert. Diese Dissertation erbringt also eine Reihe neuer Aspekte zur Psychologie der Drosophila und wird hoffentlich in diesem Bereich der Forschung neue Wege {\"o}ffnen.}, subject = {Lernen}, language = {en} } @phdthesis{Dieler2011, author = {Dieler, Alica Christina}, title = {Investigation of variables influencing cognitive inhibition: from the behavioral to the molecular level}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-65955}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {The present work investigated the neural mechanisms underlying cognitive inhibition/thought suppression in Anderson's and Green's Think/No-Think paradigm (TNT), as well as different variables influencing these mechanisms at the cognitive, the neurophysiological, the electrophysiological and the molecular level. Neurophysiological data collected with fNIRS and fMRI have added up to the existing evidence of a fronto-hippocampal network interacting during the inhibition of unwanted thoughts. Some evidence has been presented suggesting that by means of external stimulation of the right dlPFC through iTBS thought suppression might be improved, providing further evidence for an implication of this region in the TNT. A combination of fNIRS with ERP has delivered evidence of a dissociation of early condition-independent attentional and later suppression-specific processes within the dlPFC, both contributing to suppression performance. Due to inconsistencies in the previous literature it was considered how stimulus valence would influence thought suppression by manipulating the emotional content of the to-be-suppressed stimuli. Findings of the current work regarding the ability to suppress negative word or picture stimuli have, however, been inconclusive as well. It has been hypothesized that performance in the TNT might depend on the combination of valence conditions included in the paradigm. Alternatively, it has been suggested that inconsistent findings regarding the suppression of negative stimuli or suppression at all might be due to certain personality traits and/or genetic variables, found in the present work to contribute to thought inhibition in the TNT. Rumination has been shown to be a valid predictor of thought suppression performance. Increased ruminative tendencies led to worse suppression performance which, in the present work, has been linked to less effective recruitment of the dlPFC and in turn less effective down-regulation of hippocampal activity during suppression trials. Trait anxiety has also been shown to interrupt thought suppression despite higher, however, inefficient recruitment of the dlPFC. Complementing the findings regarding ruminative tendencies and decreased thought inhibition a functional polymorphism in the KCNJ6 gene, encompassing a G-to-A transition, has been shown to disrupt thought suppression despite increased activation of the dlPFC. Through the investigation of thought suppression at different levels, the current work adds further evidence to the idea that the TNT reflects an executive control mechanism, which is sensitive to alterations in stimulus valence to some extent, neurophysiological functioning as indicated by its sensitivity to iTBS, functional modulations at the molecular level and personality traits, such as rumination and trait anxiety.}, subject = {Kognitiver Prozess}, language = {en} } @phdthesis{Deb2011, author = {Deb, Jolly}, title = {Role of Transcription Factor NFATc1 in Development, Survival and Function of B Lymphocytes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-57050}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Die Transkriptionsfaktoren der NFAT-Proteinfamilie (Nuclear Factor of Activated T cells, NFATc1-4) sind an entscheidender Stelle in die Regulation des Zellzyklus, des programmierten Zelltodes und der Kanzerogenese involviert. NFATc1 nimmt innerhalb dieser Familie eine Sonderrolle ein, da dessen Aktivit{\"a}t auch durch eine stark induzierbare Expression gesteigert werden kann. Dies ist insbesondere f{\"u}r die Differenzierung und Funktion von T- und B-Lymphozyten von Bedeutung. Weiterhin ist NFATc1 f{\"u}r die Muskel- oder Herzentwicklung notwendig. Eine Reihe von Arbeiten belegen dar{\"u}ber hinaus eine Beteiligung dieses Transkriptionsfaktors an der Entstehung von Leuk{\"a}mien und Lymphomen. W{\"a}hrend klassische Hodgkin-Lymphome allerdings durch eine abgeschaltete NFATc1-Expression gekennzeichnet sind, wird f{\"u}r T-ALL (Akute Lymphatische Leuk{\"a}mie der T-Zelle) eine {\"U}berexpression beschrieben. Die Kernlokalisation dieses Transkriptionsfaktors erfolgt nach Dephosphorylierung des zytoplasmatischen Proteins durch die Phosphatase Calcineurin. Deren Phosphataseaktivit{\"a}t wird durch einen Anstieg des intrazellul{\"a}ren Ca++-Spiegels aktiviert. Inwiefern die Calcineurin-abh{\"a}ngige Kerntranslokalisation den einzigen Aktivierungsmechanismus f{\"u}r NFAT-Faktoren darstellt, ist noch nicht eindeutig gekl{\"a}rt. Nach optimaler Aktivierung von T- bzw. B-Zellen ist die kurze, induzierbare Isoform NFATc1/A das Hauptprodukt des NFATc1-Gens. In dieser Arbeit wurden f{\"u}r die gezielte Deletion des NFATc1-Gens in der Maus zwei verschiedene konditionelle Systeme verwandt. Hierzu wurden Tiere, die ein mit „flox"-Sequenzen versehenes drittes Exon des NFATc1-Gens in der Keimbahn tragen, mit verschiedenen Cre-Rekombinase expremierenden Linien verkreuzt. Der Verlust funktionellen NFATc1-Proteins erfolgt dann fr{\"u}h in der B-Zell-Differenzierung im Knochenmark (Cd79a/mb-1-cre x Nfatc1flx/fl) bzw. in reifen B-Zellen (Cd23-cre x Nfatc1flx/flx). W{\"a}hrend in keiner dieser Linien signifikante Defekte in der Differenzierung "konventioneller B2" B-Lymphozyten beobachtet wurden, hatte die fr{\"u}he Inaktivierung des NFATc1-Gens im Knochenmark den Verlust der B1a-Zell-Population im Peritoneum zur Folge. In vitro zeigten NFATc1-/--B-Zellen aus der Milz nach Aktivierung {\"u}ber den B-Zell-Rezeptor deutliche Defekte in der Zellteilung bei einer gleichzeitigen Zunahme des aktivierungsinduzierten Zelltodes (AICD, activation induced cell death). Die vergleichende Transkriptomanalyse identifizierte wichtige Gene des Ca++/Calcineurin-Signalweges als NFATc1-Zielgene und mitverantwortlich f{\"u}r die Proliferationsdefekte. In NFATc1-defizienten B-Zellen konnte Re-Expression von NFATc1 in geringer Konzentration den aktivierten Zelltod inhibieren, wohingegen hohe Konzentrationen diesen noch weiter f{\"o}rderten. Zusammengenommen l{\"a}sst sich daher schließen, dass NFATc1 entscheidend an der Kontrolle von Proliferation und Zelltod peripherer B-Lymphozyten beteiligt ist. Eine weitere wichtige Funktion kommt NFATc1 beim Klassenwechsel im Immunglobulin-Lokus zu. In den untersuchten M{\"a}usen war die IgG3-Produktion nach Immunisierung mit NP-Ficoll (einem T-Zell-unabh{\"a}ngigen Antigen des Typs II) deutlich reduziert, wenn das NFATc1-Gen in den B-Lymphozyten funktionslos war. Auch die Bildung von IgG3+-Plasmablasten war gehemmt. Zu {\"a}hnlichen Ergebnissen f{\"u}hrten Untersuchungen an isolierten B-Lymphozyten in einem in vitro Klassenwechsel-Modell. Demgegen{\"u}ber zeigten Immunisierungen der Tiere mit NP-KLH (einem T-Zell-abh{\"a}ngigen Antigen) keine signifikanten Abweichungen im Klassenwechsel. Zusammengefasst zeigen diese Daten die große Bedeutung des Transkriptionsfaktors NFATc1 f{\"u}r das {\"U}berleben und die Funktion peripherer B-Lymphozyten.}, subject = {NFATc1}, language = {en} } @phdthesis{Beisser2011, author = {Beisser, Daniela}, title = {Integrated functional analysis of biological networks}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-70150}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {In recent years high-throughput experiments provided a vast amount of data from all areas of molecular biology, including genomics, transcriptomics, proteomics and metabolomics. Its analysis using bioinformatics methods has developed accordingly, towards a systematic approach to understand how genes and their resulting proteins give rise to biological form and function. They interact with each other and with other molecules in highly complex structures, which are explored in network biology. The in-depth knowledge of genes and proteins obtained from high-throughput experiments can be complemented by the architecture of molecular networks to gain a deeper understanding of biological processes. This thesis provides methods and statistical analyses for the integration of molecular data into biological networks and the identification of functional modules, as well as its application to distinct biological data. The integrated network approach is implemented as a software package, termed BioNet, for the statistical language R. The package includes the statistics for the integration of transcriptomic and functional data with biological networks, the scoring of nodes and edges of these networks as well as methods for subnetwork search and visualisation. The exact algorithm is extensively tested in a simulation study and outperforms existing heuristic methods for the calculation of this NP-hard problem in accuracy and robustness. The variability of the resulting solutions is assessed on perturbed data, mimicking random or biased factors that obscure the biological signal, generated for the integrated data and the network. An optimal, robust module can be calculated using a consensus approach, based on a resampling method. It summarizes optimally an ensemble of solutions in a robust consensus module with the estimated variability indicated by confidence values for the nodes and edges. The approach is subsequently applied to two gene expression data sets. The first application analyses gene expression data for acute lymphoblastic leukaemia (ALL) and differences between the subgroups with and without an oncogenic BCR/ABL gene fusion. In a second application gene expression and survival data from diffuse large B-cell lymphomas are examined. The identified modules include and extend already existing gene lists and signatures by further significant genes and their interactions. The most important novelty is that these genes are determined and visualised in the context of their interactions as a functional module and not as a list of independent and unrelated transcripts. In a third application the integrative network approach is used to trace changes in tardigrade metabolism to identify pathways responsible for their extreme resistance to environmental changes and endurance in an inactive tun state. For the first time a metabolic network approach is proposed to detect shifts in metabolic pathways, integrating transcriptome and metabolite data. Concluding, the presented integrated network approach is an adequate technique to unite high-throughput experimental data for single molecules and their intermolecular dependencies. It is flexible to apply on diverse data, ranging from gene expression changes over metabolite abundances to protein modifications in a combination with a suitable molecular network. The exact algorithm is accurate and robust in comparison to heuristic approaches and delivers an optimal, robust solution in form of a consensus module with confidence values. By the integration of diverse sources of information and a simultaneous inspection of a molecular event from different points of view, new and exhaustive insights into biological processes can be acquired.}, subject = {Bioinformatik}, language = {en} } @phdthesis{Angermeier2011, author = {Angermeier, Hilde Gabriele}, title = {Molecular and ecological investigations of Caribbean sponge diseases}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-56855}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {W{\"a}hrend gewinnbringende Assoziationen von Schw{\"a}mmen mit Mikroorganismen in den letzten Jahren viel Aufmerksamkeit erhalten haben, wurde weit weniger in die Interaktion von Schw{\"a}mmen mit m{\"o}glicherweise pathogenen Mikroben investiert. Somit war es das Ziel dieser Studie zwei ausgew{\"a}hlte Karibische Schwammkrankheiten namens „Sponge Orange Band" und „Sponge White Patch" mittels {\"o}kologischer und molekularer Methoden zu untersuchen. Die Sponge Orange Band (SOB) Erkrankung bef{\"a}llt den bedeutenden karibischen Fass-Schwamm Xestospongia muta, der zu den bakterienhaltigen (HMA) Schw{\"a}mmen gez{\"a}hlt wird, w{\"a}hrend die Sponge White Patch (SWP) Erkrankung den h{\"a}ufig vorkommenden Seil-Schwamm Amphimedon compressa betrifft, der zu den bakterienarmen (LMA) Schw{\"a}mmen geh{\"o}rt. F{\"u}r beide Karibischen Schwammkrankheiten konnte ich einen Krankheitsverlauf beschreiben, der mit massiver Gewebszerst{\"o}rung und dem Verlust charakteristischer mikrobieller Signaturen einhergeht. Obwohl ich zeigen konnte, dass zus{\"a}tzliche Bakterienarten die gebleichten Schwammbereiche kolonisieren, lieferten meine Infektionsversuche in beiden F{\"a}llen keinen Beweis f{\"u}r die Beteiligung eines mikrobiellen Pathogens als Krankheitserreger. Somit liegen die eigentlichen Ausl{\"o}ser der Erkrankungen Sponge Orange Band als auch Sponge White Patch noch immer im Dunkeln.}, subject = {Meeresschw{\"a}mme}, language = {en} }