Unusual Mitochondrial Genome Structures throughout the Euglenozoa

Mitochondrial DNA of Kinetoplastea is composed of different chromosomes, the maxicircle (bearing ‘regular’ genes) and numerous minicircles (specifying guide RNAs involved in RNA editing). In trypanosomes [Kinetoplastea], DNA circles are compacted into a single dense body, the kinetoplast. This report addresses the question whether multi-chromosome mitochondrial genomes and compacted chromosome organization are restricted to Kinetoplastea or rather occur throughout Euglenozoa, i.e., Kinetoplastea, Euglenida and Diplonemea. To this end, we investigated the diplonemid Rhynchopus euleeides and the euglenids Petalomonas cantuscygni, Peranema trichophorum and Entosiphon sulcatum, using light and electron microscopy and molecular techniques. Our findings together with previously published data show that multi-chromosome mitochondrial genomes prevail across Euglenozoa, while kinetoplast-like mtDNA packaging is confined to trypanosomes.