Presence of a mitochondrial-type 70-kDa heat shock protein in Trichomonas vaginalis suggests a very early mitochondrial endosymbiosis in eukaryotes

摘要

Molecular phylogenetic analyses, based mainly on ribosomal RNA, show that three amitochondriate protist lineages, diplomonads, microsporidia, and trichomonads, emerge consistently at the base of the eukary- otic tree before groups having mitochondria. This suggests that these groups could have diverged before the mitochon- drial endosymbiosis. Nevertheless, since all these organisms live in anaerobic environments, the absence of mitochondria might be due to secondary loss, as demonstrated for the later emerging eukaryote Entamoeba histolytica.