My laboratory is investigating mtDNAs of Euglenozoa, a large group of unicellular eukaryotes that are believed to have emerged very early in eukaryotic history. This monophyletic lineage includes most diverse phyla such as euglenids, kinetoplastids, and diplonemids. The latter two are sistergroups that split off after the divergence of euglenids.
The main focus of our work is on diplonemids (see list of publications).
In Diplonema papillatum, we discovered
an unprecedented mitochondrial genome architecture and gene structure. This mtDNA
consists of >100 different circular
chromosomes, each of which carries a small gene module. Gene modules are transcribed
individually and then joined together to a contiguous mRNA by trans-splicing. Further,
we detected RNA editing, a rare event proceeding by insertion of multiple Us at a single site
(Marande & Burger, 2007).
Our working hypothesis is that trans-splicing and RNA editing in diplonemids is mediated by small RNA molecules, similar to guideRNAs that direct RNA editing in kinetoplastid mitochondria. To test this hypothesis, we use molecular-biology and bioinformatics approaches. Experimental data help to formulate specific search strategies and vice versa, bioinformatics hypotheses are being tested experimentally.
Finally, we have initiated exploring mtDNAs of euglenids (Roy et al, 2007a, b), basal kinetoplastids and yet undescribed diplonemids, in order to trace back the evolution and dispersal of RNA editing in Euglenozoa.
The second genome project is the Unicorn initiative, a collaboration of seven research groups from Canada, UK, and USA, and endorsed by the National Human Genome Research Institute (NHGRI). This project aims at understanding how multicellularity first evolved. Genomic data are being generated from unicellular relatives of animals and fungi, i.e., choanflagellates, Ichthyosporea, Nuclearidae, chytrids, zygomycetes and apusozoa (outgroup) (see e.g., Ruiz-Trillo I et al, 2007).