Fakultät für Biologie - Digitale Hochschulschriften der LMU - Teil 03/06

Die Bedeutung von angeborenen Effektorzellen waehrend einer Typ 2 Immunantwort

Wurminfektionen und allergische Reaktionen sind mit einer starken Zunahme von Interleukin-4 (IL-4)-produzierenden Zellen des angeborenen und adaptiven Immunsystems assoziiert. In dieser Arbeit wurden einige grundlegende Eigenschaften IL-4-produzierender Zellen des angeborenen Immunsystems untersucht. Es konnte gezeigt werden, dass die Zunahme eosinophiler und basophiler Granulozyten nach Infektion mit dem gastrointestinalen Nematoden Nippostrongylus brasiliensis auf unterschiedliche Art regu...

Cell proliferation and cell survival in the dentate gyrus of adult mice under naturalistic conditions

Throughout life, new cells are generated in the mammalian brain and incorporated as functional neurons in the networks of the olfactory bulb and the dentate gyrus (DG) of the hippocampal formation. So far proliferation and survival rates of newly generated cells in the adult DG have been investigated in commonly used and rather simple behavioral experiments like the Morris water maze, fear and trace conditioning, a running wheel and small enriched environments. Some of these studies gave evid...

Mechanisms of B cell activation and lymphomagenesis

Diaphanous-related formins

Das komplexe Netzwerk Apoptose regulierender Proteine in Hydra

Evolution of dioecy in the Cucurbitaceae genus Bryonia

Genetic crosses between the dioecious Bryonia dioica Jacq. (Cucurbitaceae) and the monoecious B. alba L. in 1903 provided the first clear evidence for Mendelian inheritance of dioecy and made B. dioica the classic case of XY sex determination in plants. We use chloroplast (cp) and nuclear (nr) DNA sequences from 129 individuals representing all morphological species to study species relationships and distribution, sexual system evolution, and association of ploidy-level with dioecy in Bryonia...

TAP38 - a key player in LHCII dephosphorylation

Charakterisierung des HER2-Signalwegs im Vergleich von 2D- und 3D-Zellkultur und in einer Trastuzumab resistenten SKBR-3-Zelllinie

Die Charakterisierung und Kultivierung von Tumorzelllinien mit Hilfe einer zweidimensionalen (2D) Zellkultur gilt als Standardmethode in der Zellbiologie. Dreidimensionale (3D) Modelle gewinnen jedoch immer mehr an Bedeutung, da sie die Tumorbiologie in Bezug auf physiologisch relevante Zusammenhänge bei der Tumorentstehung und –progression besser abbilden als eine herkömmliche 2D-Kultur. Die auf poly-HEMA beschichteten Zellkulturplatten induzierten multizellulären Tumorspheroide reflektieren...

Funktion und Expression der transmembranen Isoformen des HLA-Klasse-III-Gens LST1

Dendritic spines and structural plasticity in Drosophila

The morphology of dendrites is important for neuronal function and for the proper connectivity within neuronal circuits. The often very complex shape of dendritic trees is brought about by the action of many different genes throughout development. Moreover, neuronal activity is often involved in refining synaptic connections and shaping dendrites. Aiming at a better understanding of the interplay between genes and neuronal activity during dendrite differentiation I was trying to identify suit...

Molekulare Studien zur Effizienz und Stabilität EBV-basierender extrachromosomaler Genvektoren

Jmjd6 katalysiert Lysin-5-Hydroxylierungen an U2AF-65 und ist ein potentieller Regulator des Spleißprozesses

The role of ephrinB signaling during synaptic plasticity

Autotrophy in Groundwater Ecosystems

The major role in global net CO2 fixation plays photosynthesis of green plants, algae and cyanobacteria, but other microorganisms are also important concerning autotrophy; i.e. autotrophic microorganisms can be found in most bacterial groups (Eubacteria) and there are even numerous representatives within the Archaea. CO2 fixation is not only one of the world’s most important biogeochemical processes and responsible for the buildup of organic compounds which are needed for biological functions...

Impact of glyphosate application to transgenic Roundup Ready® soybean on horizontal gene transfer of the EPSPS gene to Bradyrhizobium japonicum and on the root-associated bacterial community

Abstract In this study, two topics causing major public concern related to transgenic plants were investigated: The possibility of a horizontal gene transfer from plant to bacteria and the impact of transgenic plants after herbicide treatment on root associated bacteria. The transgenic plant chosen for this study was Roundup Ready® (RR) soybean, which is tolerant to the herbicide glyphosate and is the most commonly used genetically modified crop worldwide. Glyphosate, the active ingredient o...

Coordination of synaptonemal complex formation and pachytene checkpoint signaling in meiosis

Intracellular processing of motion information in a network of blowfly visual interneurons

In the past few decades, the lobula plate of the fly has emerged as one of the leading models for the neural processing of optic flow stimuli that give rise to visual orientation behaviors (for recent reviews see Borst and Haag, 2002; Egelhaaf et al., 2002; Egelhaaf et al., 2002; Borst and Haag, 2007). The relative simplicity and accessibility of this neural system allows researchers to characterize the neural mechanisms that are thought to link the visual stimuli and the resulting behavioral...

Neue Funktionen von Xrs2 für die Aufrechterhaltung genomischer Stabilität in der Hefe S. cerevisiae

Functional characterisation of microRNA-containing Argonaute protein complexes

microRNAs (miRNAs) are small non-coding RNAs of 21-24 nt in size, which are endogenously expressed in higher eukaryotes and play important roles in processes such as tissue development and stress response and in several diseases including cancers. In mammals, miRNAs guide proteins of the Argonaute family (Ago proteins) to partially complementary sequences typically located in the 3’-untranslated regions (3’-UTRs) of specific target mRNAs, leading to translational repression or mRNA degradatio...

Magnetosome-specific expression of chimeric proteins in Magnetospirillum gryphiswaldense for applications in cell biology and biotechnology

Magnetosomes are magnetic nanoparticles that are formed by magnetotactic bacteria (MTB) by a complex, genetically controlled biomineralization process. Magnetosomes from the model organism Magnetospirillum gryphiswaldense consist of single-magnetic-domain sized nanocrystals of chemically pure magnetite, which are formed intracellularly within specialized membranous compartments. The natural coating by the biological membrane and the defined physico-chemical properties designate magnetosomes a...

Untersuchungen zur Modulation der Somatischen Hypermutation durch Transkriptionsfaktoren

Condition dependence and fitness consequences of sexual traits in zebra finches

The focus of this thesis is on sexual selection within a behavioural and evolutionary framework. Sexual selection is concerned with the factors that determine reproductive success. I have used a laboratory population of zebra finches to address fundamental questions that remain unanswered despite decades of research on this model organism in studies of sexual selection in monogamous species. The aim of this thesis was to perform a rigorous investigation of how male zebra finches achieve repro...

Developmental function of PirB restricts adult ocular dominance plasticity

Early visual input induces changes in functional connectivity which can either lead to the stabilisation of appropriate synaptic connections or the elimination of inappropriate ones in the visual system. Monocular deprivation (MD) is a widely used paradigm to study changes in ocular dominance (OD) in the binocular visual cortex of higher mammals. Closure of one eye for several days leads to a shift in OD which re ects changes in the response kinetics of the deprived and the non-deprived eye. ...

Isolation of multipotent astroglia form the adult stem cell niche and the injured brain

Adult neural stem cells, as the source of life-long neurogenesis, reside in the subependymal zone (SEZ) in the lateral wall of the lateral ventricles and in the dentate gyrus of the hippocampus. In both neurogenic regions, subsets of glial fibrillary acidic protein (GFAP) expressing astrocytes are found, that have been shown to act as neural stem cells. So far, it is not known how to distinguish these stem cell astrocytes from other astrocyte populations within the SEZ. Towards this end we de...

Coevolution in the slavemaking ant Protomognathus americanus and its Temnothorax host species

The aim of this thesis was to investigate the coevolutionary arms race between the slavemaker P. americanus and its Temnothorax host species from different perspectives. Previous studies on this obligate social parasite have already demonstrated the evolution of morphological, behavioral and chemical adaptations, and have given variable results on the strength of the selection pressure exerted by this parasite. Based on these results, Publication 1 investigates the direct and causal relations...

The auditory cortex of the bat Phyllostomus discolor

The auditory cortex is the acoustically responsive part of the neocortex and represents the highest level of processing of the ascending auditory pathway. The experiments described in this thesis were designed to study the auditory cortex of the microchiropteran bat Phyllostomus discolor with both, simple and complex acoustic stimuli. During the experiments, different methods were used (e.g. psychophysics and neuroanatomy), but the main focus was laid on the electrophysiological examination o...

Identification and Functional Characterization of Genetic Risk Factors in Alzheimer´s Disease

Characterization of two components of the chloroplastic Tic complex

Phylogenetische und taxonomische Untersuchungen an der Subtribus Menthinae (Lamiaceae, Nepetoideae, Mentheae) unter besonderer Berücksichtigung des Satureja-Komplexes

Characterization of the Alb3/Oxa1/YidC protein family in Arabidopsis thaliana

Proteomic analysis of the Rad18 interaction network in DT40

C- jun downregulation sensitizes hepatoma cells to receptor induced apoptosis through preventing FADD phosphorylation

Kapazitive Aktivierung von Calciumkanälen mit Halbleiterchips

Characterisation of components and mechanisms involved in redox-regulation of protein import into chloroplasts

The vast majority of chloroplast proteins is encoded in the nucleus and thus has to be posttranslationally imported into the organelle, a process that is facilitated by two multimeric protein machineries, the Toc and Tic complexes (translocon at the outer/inner envelope of chloroplasts). Regulation of protein import, e.g. by redox signals, is a crucial step to adapt the protein content to the biochemical requirements of the organelle. In particular, one subunit of the Tic complex, Tic62, has ...

Causes of between-individual differences in mating preferences

Electrical activity suppresses intrinsic growth competence in adult primary sensory neurons

The ability of neurons to regenerate in the adult mammalian central nervous system (CNS) is often poor, leading to persistent deficits after injury. Failure of axon regeneration in the CNS has been attributed to the presence of an extrinsic inhibitory environment and to an intrinsic limitation to support growth. Remarkably, in adult primary sensory neurons of the dorsal root ganglia (DRG), a peripheral lesion primes neurons to grow and to override the inhibitory environment. Under this condit...

Assessing the complex nature of behavior

To unravel the molecular pylons of innate anxiety, a well established animal model has been characterized using transcriptome- and sequence-based analyses. The animal model – hyper (HAB) and hypo (LAB) anxious mice – has been created by selective inbreeding based on outbred CD1 mice using the extreme values the mice spent on the open arm of the elevated plus-maze, a test also used to screen drugs for anxiolytic or anxiogenic effects. These mice proved a robust phenotypic divergence, also for ...

The persistence of recombinant adenoviral vectors

Recombinant adenoviral vectors (rAdV) are commonly used as gene transfer vehicles and in gene therapy. Recombinant first generation vectors lack the early genes E1 and E3 (E1/E3) which makes way for insertion of up to 8.2 kb of foreign DNA. Gene-deleted adenoviral vectors (GD AdV) lacking all viral coding sequences contain only the inverted terminal repeats (ITR) and a packaging signal at its genomic termini. Hence, there is space for the insertion of coding sequences of up to 36 kb of thera...

Identifizierung und Charakterisierung eines phospho-regulierten SUMO-Interaktions-Motivs

Regionalization of adult neurogenesis

The vast majority of neurons in the murine brain are generated during embryonic neurogenesis. However, at least two neurogenic niches continue to produce specific types of neurons throughout life. The adult dentate gyrus harbours stem cells that generate dentate granule neurons and the subependymal zone produces distinct types of olfactory interneurons. The adult neurogenic subependymal zone is derived from the embryonic dorsal and ventral subventricular zone of the telencephalon, i. e. proge...

Searching for genes involved in the adaptation of Drosophila melanogaster to the European climate

The aim of the present work was to identify the genes that played a role in ecological adaptation in D. melanogaster. This species, which originated in Africa, successfully adapted to a broad range of climates during the last 100.000 years. To find the genes involved, I used two different approaches: (1) a genomic region containing several ecologically relevant candidate genes and putatively carrying footprints of selection was investigated using selective sweep mapping, and (2) cold toleranc...

Influence of flood disturbances and biotic interactions on the microdistribution of stream invertebrates

Most living communities form a temporally shifting patchwork of irregularly distributed organisms. Besides many habitat-specific biotic and abiotic environmental conditions, two key drivers are known to shape community structure: abiotic disturbance and biotic interactions (most notably competition and predation). Few other ecosystems possess either the frequency or intensity of disturbances observed in running waters. Therefore, disturbance (mainly in the form of floods) is discussed to be t...

Genetic analysis of the FLRT family of proteins during early mouse embryonic development

Effect of temperature and light intensity on the representation of motion information in the fly's visual system

To comprehend how the brain performs efficient computation, it is important to understand the way sensory information is represented in the nervous system. Under natural conditions, sensory signals have to be processed with sufficient accuracy under functional and resources constraints. Here I use motion vision in the fly Calliphora vicina to study the influence of two behaviorally relevant environmental properties - temperature and light intensity - on the representation of motion informatio...

Neuronale Kontrolle von Echoortungs- und Kommunikationslauten bei der Fledermaus Phyllostomus discolor

Vokalisationen von Fledermäusen können in zwei Gruppen unterteilt werden: Kommunikationslaute und Echoortungslaute. Diese Arbeit wurde durchgeführt, um herauszufinden, ob in die Steuerung der unterschiedlichen Laute unterschiedliche Hirnstrukturen involviert sind. Dazu wurden zwei Hirnstrukturen zur näheren Betrachtung herangezogen und ihre Funktion und Verschaltung zueinenander innerhalb der Vokalisationsbahn untersucht. Diese Strukturen waren zum einen das periaquädukte Grau (PAG) oder zent...

Monitoring Tropical Forest Degradation and Deforestation in Borneo, Southeast Asia

Genetische Veränderungen als prognostische Marker in therapeutisch bestrahlten Plattenepithelkarzinomen des Kopf-Hals-Bereiches

Imaging cellular mechanisms of presynaptic structural plasticity

Regulation of AMPA receptor function and synaptic localization by stargazin and PSD-95

The majority of excitatory transmission in the brain is mediated by glutamatergic synapses. Rapid synaptic signaling is mediated by AMPA and kainate receptors, whereas NMDA receptors mediate slow synaptic currents. Pathophysiological activation of glutamatergic neurons can lead to excitotoxicity and neuronal death, for example in ischaemia and neurodegenerative disorders. Therefore, studying the structure and function of AMPA receptors is important for understanding general mechanisms of syna...

Analysis of Protein Interactions Controlling DNA Methyltransferases