Genom-Analysen und Zellbiologie von hoch polyploiden, großen Schwefelbakterien

• Antragstellerin: Dr. Verena Carvalho, Ph.D.
• Fachliche Zuordnung: Stoffwechselphysiologie, Biochemie und Genetik der Mikroorganismen ; Evolutionäre Zell- und Entwicklungsbiologie der Tiere
• Förderung: Förderung von 2012 bis 2015
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 226167356

Evolution has yielded to current knowledge only two prokaryotic groups that grow to extreme cell sizes of several hundred micrometer - symbionts of surgeon fish (Epulopiscium fishelsonii) and large sulfur bacteria (e.g., Thiomargarita namibiensis). Since their discovery, these giant cells have fascinated the scientific community, but only little information was gained so far regarding specific adaptive mechanisms to realize these sizes. The formation of a thin peripheral layer of active cytoplasm is the most prominent intracellular deviation that was described so far. Recently, it was discovered that both organisms feature an enormous number of nucleoids, i.e. compressed particles of nucleic acid, providing further evidence that there exist more subcellular features in giant bacteria that are aberrant from regular sized prokaryotes. In Epulopiscium sp., these nucleoids represent several hundred thousands of genome copies - a finding which is so far unprecedented. It was hypothesized that this extreme polyploidy allows an even supply of genetic information and local functional independence. I propose that this extreme polyploidy exists also in giant sulfur bacteria, which will be investigated in Thiomargarita spp. during this project. Concomitant with polyploidy, the level of genome conservation needs to be addressed and will be the main focus of this project. Detailed sequence comparison of selected genes and whole genomes will be conducted, using not only single cells, but also cell fragments cut from a single cell, allowing an in-depth analysis of intergenomic heterogeneity. A side-aspect of the project will cover the latest finding of introns in the 16S rRNA genes of large sulfur bacteria - a gene used as fundamental character in phylogenetic and diversity studies.

• DFG-Verfahren: Forschungsstipendien
• Internationaler Bezug: USA
• Gastgeberinnen / Gastgeber: Professorin Dr. Esther Angert, Ph.D.; Professor Dr. Andreas Teske