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 <italic>numt</italic>) in two closely related species of lampreys (<italic>Ichthyomyzon</italic> spp.). Although <italic>numts</italic> have been characterized in several vertebrate taxa, <italic>numts</italic> have yet to be reported for fishes in general. Given the phylogenetic position of lampreys relative to other vertebrates, the presence of <italic>numts</italic> 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. [ABSTRACT FROM AUTHOR]