First Report of a Mitochondrial Pseudogene in Agnathan Vertebrates (Cyclostomata: Petromyzontidae).

We report herein the characterization of a nuclear paralog of a fragment of the mitochondrial genome (a numt) in two closely related species of lampreys (Ichthyomyzon spp.). Although numts have been characterized in several vertebrate taxa, numts have yet to be reported for fishes in general. Given the phylogenetic position of lampreys relative to other vertebrates, the presence of numts within the lamprey genome is either evidence of an ancestral trait lost in other fishes but uniquely retained in agnathans and amniotes, or (more intriguingly) a product of the genome rearrangements these animals undergo during development.