The single mitochondrial chromosome typical of animals has evolved into 18 minichromosomes in the human body louse, Pediculus humanus
- 1 The University of Queensland, Parasitology Section, School of Chemistry and Molecular Biosciences, Queensland 4072, Australia;
- 2 The J. Craig Venter Institute, Rockville, Maryland 20850, USA
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↵3 These authors contributed equally to this work.
Abstract
The mitochondrial (mt) genomes of animals typically consist of a single circular chromosome that is ∼16-kb long and has 37 genes. Our analyses of the sequence reads from the Human Body Louse Genome Project and the patterns of gel electrophoresis and Southern hybridization revealed a novel type of mt genome in the sucking louse, Pediculus humanus. Instead of having all mt genes on a single chromosome, the 37 mt genes of this louse are on 18 minicircular chromosomes. Each minicircular chromosome is 3–4 kb long and has one to three genes. Minicircular mt chromosomes are also present in the four other species of sucking lice that we investigated, but not in chewing lice nor in the Psocoptera, to which sucking lice are most closely related. We also report unequivocal evidence for recombination between minicircular mt chromosomes in P. humanus and for sequence variation in mt genes generated by recombination. The advantages of a fragmented mt genome, if any, are currently unknown. Fragmentation of mt genome, however, has coevolved with blood feeding in the sucking lice. It will be of interest to explore whether or not life history features are associated with the evolution of fragmented chromosomes.
Footnotes
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↵4 Corresponding author.
E-mail r.shao{at}uq.edu.au; fax 61-7-33654699.
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[The nucleotide sequences of the minicircular mitochondrial chromosomes reported in this study have been submitted to GenBank (http://www.ncbi.nlm.nih.gov/Genbank/) under accession nos. EU219983–EU219995, FJ499473–FJ499490, and FJ514591–FJ514599.]
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Article published online before print. Article and publication date are at http://www.genome.org/cgi/doi/10.1101/gr.083188.108.
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- Received July 9, 2008.
- Accepted December 24, 2008.
- Copyright © 2009 by Cold Spring Harbor Laboratory Press
