Distribution of nuclear mitochondrial DNA in cattle nuclear genome.

The nuclear mitochondrial pseudogenes (numts), originated from mtDNA insertions into the nuclear genome, have been detected to exist in many species. However, the distribution of numts in cattle nuclear genome yet has not been fully reported. By referring to the whole cattle mtDNA sequence and to the recently released cattle nuclear genome by Human Genome Sequencing Center (HGSC), 303 numts were identified by BLAST with 55 numts unmapped to cattle nuclear genome. Further analysis found that the size of the numts ranges from 37 to 1932 bp, and the homologous identity between numts and their corresponding mtDNA fragments varies from 73 to 98%. Furthermore, the identified cattle numts cover nearly all the mitochondrial genes including mtDNA control region, distributing over all the chromosomes with the exception of the chromosome 23 and Y chromosome (in the latter the sequence data are not available). In the discovered numts, 29 relatively complete mitochondrial genes, which were distributed in 72 numts, were detected. Undoubtedly, this research would provide some valuable information for successive research related to mitochondrial genes and the evolution of cattle.