Poster Presentation Society for Molecular Biology and Evolution Conference 2016

Insight into the evolution of the partitioned mitochondrial genome of Myxozoa (Metazoa, Cnidaria). (#525)

Dayana Yahalomi 1 , Arik Diamant 2 , Huchon Dorothee 1 3
  1. Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv , Israel
  2. National Center for Mariculture, Israel Oceanographic and Limnological Research, Eilat, Israel
  3. The Steinhardt Museum of Natural History and Israel National Center for Biodiversity Studies, Tel Aviv University, Ramat Aviv , Israel

Myxozoans form a large group of poorly characterized parasites, which are nested within cnidarians. Complete myxozoan mitochondrial (mt) genomes have been characterized only from two genera: Kudoa and Enteromyxum. Species from the genus Kudoa, possess a rather standard mt genome: a single circular mt chromosome of ~18 kb. In contrast, Enteromyxum leei, possesses a fragmented genome divided into seven circular chromosomes of ~23 kb, making it the largest described animal mt genome. Each Enteromyxum chromosome harbors one coding gene region and a large non-coding region (~15 kb), nearly identical between chromosomes. To better understand the evolution of the partitioned mt genome in Myxozoa we sequenced the complete mt genome of another myxozan genus, Sphaeromyxa.

Preliminary results indicate that the mt genome of Sphaeromyxa zaharoni is organized unlike any hitherto sequenced myxozoan genome. It is formed of two circular chromosomes (~15 kb), which share the same non-coding region (~ 700 bp). Interestingly, these two chromosomes were found to recombine to form a single large (~30 kb) chimeric circular molecule, which includes two copies of the non-coding region.

Since Sphaeromyxa is known to have diverged before Enteromyxum and Kudoa, our results suggest that genome fragmentation either occurred several times independently or that the presence of a single molecule is a secondary character in Kudoa. These observations highlight the remarkable evolutionary plasticity of mt genome organization within Myxozoa.