| What effect does a parasitic lifestyle have on the mitochondria of a parasite? Adapted to their unique lifestyle, parasites commonly take much of their energy from their host and in many cases have highly reduced mitochondrial genomes in both size and function, because mitochondria are the engines of the cell.;Evolution and classification of facultative and free-living oomycetes are much less understood than plant parasitic species and sufficient data are lacking at the genomic level for comparative analysis. The objective of this research was to sequence the mitochondrial genome (mtDNA) of Thraustotheca clavata and Achlya hypogyna. The ability to contrast a parasitic species (A. hypogyna) to a closely-related free living species (T. clavata) makes the oomycetes ideal to better understand the changes that occur when an organism fundamentally changes its lifestyle.;Both sequenced mitochondrial genomes are circular, with sizes of 46,869bp for A hypogyna and 47,380bp for T. clavata. The mitochondrial genomes share 63 genes but differ in total number and order of genes due to losses and inversion. The mtDNA include a total of 29 or 30 tRNAs ( A. hypogyna and T. clavata, respectively) specifying 19 amino acids. Three open reading frames (ORFs) are conserved, and one was identified unique to T. clavata. A. hypogyna has lost rps10 and one copy of nad2, while T. clavata has three pseudogenes (nad2, rps3, and rps7). Comparisons of these genomes with published sequences of the closely related Saprolegnia ferax mitochondrial genome and four other more distantly related oomycetes reveals a number of similarities, but the gene content and architecture are highly variable across lineages. |
