Imagine a car that runs minus not only an engine, but without most parts under the hood. A team of Czech Republic and Canadian scientists identified the
cellular equivalent in Monocercomonoides, a protozoan they isolated from a chinchilla’s gut. This is the first eukaryote — organisms, like plants and
animals, whose cells contain distinct nuclei — found without the machinery of mitochondria.
These cellular powerhouses can perform many jobs. Mitochondria produce energy, and they glom onto iron and sulfur to help proteins make needed chemicals. A
few related pathogens have simpler mitochondria that only perform the iron-clustering duty. When the team analyzed the Monocercomonoides genome, genes
associated with all mitochondrial functions were missing.
So how does the organism survive? “It stole or borrowed clustering systems from bacteria,” says Anna Karnkowska, now at the University of British Columbia
in Vancouver. The work was published in the journal Current Biology in May.
The rarity of this exception confirms mitochondria’s importance, Karnkowska says, adding that next up is searching for evidence in close relatives that
shows how mitochondria were completely lost.