Mitochondrial Introgressions into the Nuclear Genome of the Domestic Cat

Translocation of mtDNA into the nuclear genome, also referred to as numt, was first reported in the domestic cat (Felis catus) by Lopez et al. (1994). The Lopez-numt consisted of a translocation of 7.9 kbp of mtDNA that inserted into the domestic cat chromosome D2 around 1.8 million years ago. More than a decade later, the release of the domestic cat whole-genome shotgun sequences (1.9x coverage) provides the resource to obtain more comprehensive insight into the extent of mtDNA transfer over time in the domestic cat genome. MegaBLAST searches revealed that the cat genome harbors a wide variety of numts (298 320 bp), one-third of which likely correspond to the Lopez-numt tandem repeat, whereas the remaining numts are probably derived from multiple independent insertions, which in some cases were followed by segmental duplication after insertion in the nucleus. Numts were detected across most cat chromosomes, but the number of numts assigned to chromosomes is underestimated due to the relatively high number of numt sequences with insufficient flanking sequence to map. The catalog of cat numts provides a valuable resource for future studies in Felidae species, including its use as a tool to avoid numt contaminations that may confound population genetics and phylogenetic studies.