Letter: High-level of Heteroplasmy in the Mitochondrial Cox1- Minichromosome of the Human Body Louse, Pediculus humanus, and the Human Head Louse, Pediculus capitis

The mitochondrial (mt) genome of bilateral animals typically consists of a single chromosome, ~16 kb long, and contains 37 genes. Variation in mt gene sequence within an individual, i.e. heteroplasmy, is common in bilateral animals but usually occurs at very low levels. In the lineage that led to the human body louse, the typical mt chromosome has fragmented into 18 minichromosomes: each minichromosome is 3 to 4 kb long and contains 1 to 3 genes and a noncoding region. To understand the presence and the level of heteroplasmy in fragmented mt genomes, we cloned and sequenced seven copies of full-length cox1-minichromosome of a human body louse and a human head louse. We found 17 heteroplasmic sites in the coding region and 118 heteroplasmic sites in the non-coding region of the cox1minichromosome. The level of heteroplasmy in the human lice appears to be much higher than that in other animals that have the typical mt genome. We propose that recombination between different minichromosomes of the fragmented mt genome may contribute to the high-level of heteroplasmy in the human lice.