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Dissertation
Role of Rab5 in synaptic vesicle recycling
(2002-11-28)
During synaptic transmission, NT-filled synaptic vesicles are released by Ca2+-triggered exocytosis at the active zone. Following exocytosis, SV membrane is immediately re-internalized and synaptic vesicles (SVs) are regenerated by a local recycling mechanism within the presynaptic terminal. It is debated whether an endosomal compartment is involved in this recycling process. In contrast, it is well known from cultured mammalian cells, that endocytic vesicles fuse to the early sorting endosome. The early endosome is ...
Dissertation
Functional genomics of the Drosophila melanogaster X chromosome and the role of DWnt5 during development
(2002-12-19)
The collection of X chromosome insertions (PX) lethal lines, which was isolated from a screen for essential genes on the X chromosome, was characterized by means of cloning the insertion sites, mapping the sites within genomic DNA and determination of the associated reporter gene expresssion patterns. The established STS flanking the P element insertion sites were submitted to EMBL nucleotide databases and their in situ data together with the enhancer trap expression patterns have been deposited in the FlyView database. ...
Dissertation
Molecular mechanisms controlling the precision of chemokine guided cell migration
(2007-06-21)
By the end of the first day of embryonic development, zebrafish primordial germ cells (PGCs) arrive at the site where the gonad develops. In our study we investigated the mechanisms controlling the precision of primordial germ cell arrival at their target.
We found that in contrast with our expectations which were based on findings in Drosophila and mouse, the endoderm does not constitute a preferred migration substrate for the PGCs. Rather, endoderm derivatives are important for later stages of organogenesis keeping ...
Dissertation
The role of Ken&Barbie in JAK/STAT signalling during development of Drosophila melanogaster
(2005-02-02)
Cell-cell interactions during embryonic development are crucial in the co-ordination of growth, differentiation and maintenance of many different cell types. To achieve this co-ordination each cell must properly translate signals received from neighbouring cells, into spatially and temporally appropriate developmental responses. A surprisingly limited number of signal pathways are responsible for the differentiation of enormous variety of cell types. As a result, pathways are frequently 'reused' during development. ...
Dissertation
Characterization of the role of Drosophila JAK/STAT signalling in cellular proliferation
(2006-01-10)
Der Janus Kinase / signal transducer and activator of transcription (JAK/STAT) Signal- transduktionsweg wird für viele Entwicklungsvorgänge benötigt und spielt eine zentrale Rolle bei der Hämatopoese und bei der Immunantwort. Obwohl der JAK/STAT-Signalweg in den vergangenen Jahren Gegenstand intensiver Forschung war, erschwert die Redundanz des Signalwegs bei Wirbeltieren genetische Untersuchungen zur Identifizierung derjenigen Mechanismen, die den JAK/STAT-Signalweg regulieren. Der JAK/STAT-Signaltransduktionsweg ...
Dissertation
Studies of cap-independent mRNA translation in Drosophila melanogaster
(2005-02-02)
Control of protein synthesis is a key step in the regulation of gene expression during apoptosis and the heat shock response. Under such conditions, cap-dependent translation is impaired and Internal Ribosome Entry Site (IRES)-dependent translation plays a major role in mammalian cells. Although the role of IRES-dependent translation during apoptosis has been mainly studied in mammals, its role in the translation of Drosophila apoptotic genes has not been yet studied. The observation that the Drosophila mutant embryos ...
Dissertation
Untersuchungen zur Verbreitung von Klasse II-Transposons wie Tn21, Tn501 und Tn3 in terrestrischen Habitaten
(2005-03-14)
Mobile genetische Elementen wie Transposons wurden in unbelasteten Böden nachgewiesen. Hierzu wurden unterschiedliche Ansätze gewählt: Verschiedene, unbelastete Böden wurden mittels PCR auf das Vorhandensein von Markergenen, in diesem Fall Transposasen vom Typ Tn3, Tn21 und Tn501, hin untersucht. Hierzu wurde ein System entwickelt, welches es ermöglichte die Gesamt-DNA aus verschiedensten Böden mit einem System einfach und reproduzierbar zu extrahieren und anschließend mittels PCR zu untersuchen. Die mittlere ...
Dissertation
Molekularbiologische Funktionsanalysen von Thioredoxinen aus Dictyostelium discoideum und Identifizierung neuer Interaktionspartner durch das Two-Hybrid-System
(2002-11-28)
Thioredoxins are small, regulatory proteins with a mass of approximately 12 kDa and a characteristic conserved active center, which is represented in the pentapeptide trp-cys-gly-pro-cys. Up to now it is not possible to present a complete list of thioredoxin interaction partners because there is no predictable sequence in the target enzymes where thioredoxins can interact with. To get closer information about the functions and possible interaction partners of the three thioredoxins from the social soil amoeba ...
Dissertation
On the function of the Dictyostelium Argonaute A protein (AgnA) in epigenetic gene regulation
(2006-08-09)
With molecular biology methods and bioinformatics, the Argonaute proteins in Dictyostelium discoideum were characterized, and the function of the AgnA protein in RNAi and DNA methylation was investigated, as well as cellular features. Also interaction partners of the PAZ-Piwi domain of AgnA (PAZ-PiwiAgnA) were discovered. The Dictyostelium genome encodes five Argonaute proteins, termed AgnA/B/C/D/E. The expression level of Argonaute proteins was AgnB/D/E > AgnA > AgnC. All these proteins contain the characteristic ...
Dissertation
Molecular studies on a Dictyostelium homolog of the tafazzin gene, the cause of Barth syndrome in humans
(2003-11-11)
Der eukaryotische Mikroorganismus Dictyostelium discoideum lebt als einzellige Amöbe solange ausreichende Nahrungsressourcen zur Verfügung stehen. Sobald Nahrungsmangel eintritt, entwickeln sich die Zellen von einem einzelligen zu einem mehrzelligen Zustand, der mit einem multizellulären Fruchtkörper abschließt. Dieser Prozess wird durch eine Reihe aufeinanderfolgender Signale organisiert, die eine differentielle Genexpression regulieren. Die Gene der Discoidin I Familie gehören zu den Ersten, die im Laufe des ...