title: Novel mitochondrial gene content and gene arrangement indicate illegitimate inter-mtDNA recombination in the chigger mite, Leptotrombidium pallidum.
abstract: To better understand the evolution of mitochondrial (mt) genomes in the Acari (mites and ticks), we sequenced the mt genome of the chigger mite, Leptotrombidium pallidum (Arthropoda: Acari: Acariformes). This genome is highly rearranged relative to that of the hypothetical ancestor of the arthropods and the other species of Acari studied. The mt genome of L. pallidum has two genes for large subunit rRNA, a pseudogene for small subunit rRNA, and four nearly identical large noncoding regions. Nineteen of the 22 tRNAs encoded by this genome apparently lack either a T-arm or a D-arm. Further, the mt genome of L. pallidum has two distantly separated sections with identical sequences but opposite orientations of transcription. This arrangement cannot be accounted for by homologous recombination or by previously known mechanisms of mt gene rearrangement. The most plausible explanation for the origin of this arrangement is illegitimate inter-mtDNA recombination, which has not been reported previously in animals. In light of the evidence from previous experiments on recombination in nuclear and mt genomes of animals, we propose a model of illegitimate inter-mtDNA recombination to account for the novel gene content and gene arrangement in the mt genome of L. pallidum.
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Fukuyama, Hiroshima 729-0292, Japan. r.shao@uq.edu.au
authors.forename: Renfu
authors.initials: R
authors.lastname: Shao
authors.forename: Harumi
authors.initials: H
authors.lastname: Mitani
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Barker
authors.forename: Mamoru
authors.initials: M
authors.lastname: Takahashi
authors.forename: Masahito
authors.initials: M
authors.lastname: Fukunaga
mesh_terms: D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000235:genetics*; D019143:Evolution, Molecular; D016678:Genome; D006801:Humans; D008925:Mites; D008928:Mitochondria / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012335:RNA, Ribosomal / Q000235:genetics; D012343:RNA, Transfer / Q000235:genetics; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
chemical_list: D004272:DNA, Mitochondrial; D012335:RNA, Ribosomal; D012343:RNA, Transfer