Genomics and cell biology of oxymonads

Oxymonads are a group of poorly studied protists living as intestinal endosymbionts in the gut of insects and vertebrates. In this thesis I focused on the study of phylogeny, genomics and cell biology of oxymonads. Using culture-based approaches, we uncovered the hidden diversity of small oxymonads and described one new genus and six new species. In Monocercomonoides exilis, the only oxymonad with a published genome, we investigated the genome organization using fluorescence in situ hybdridization (FISH) against the telomeric regions and single-copy genes. Our results show that the genome is most probably haploid being organized in 6-7 chromosomes. Annotation of the genome revealed that the DNA replication and repair mechanisms in M. exilis are canonical and they seem more complete than those of other metamonads whose genomes are available. Although M. exilis lacks in any traces of mitochondria, its genome annotation revealed that other cellular systems do not markedly differ from other eukaryotes. Our taxon-rich phylogenetic analyses suggested that the genus Monocercomonoides is closely related to the oxymonad Streblomastix strix, which is found exclusively in the gut of the termites. Streblomastix strix, as opposed to M. exilis, is highly adapted to harbour bacterial ectosymbionts. Since S. strix..