Complete Mitochondrial Genome of Euseius nicholsi (Ehara et Lee) (Acari:Phytoseiidae)

The complete mitochondrial genome of Eulaelaps huzhuensis (Mesostigmata: Haemogamasidae)

Some mites of the family Haemogamasidae can transmit a variety of zoonotic diseases and have important public health and safety implications. Currently, however, little attention has been paid to molecular data of Haemogamasidae species, limiting our understanding of their evolutionary and phylogenetic relationships. In this study, the complete mitochondrial genome of Eulaelaps huzhuensis was determined for the first time, and its genomic information was analyzed in detail. The mitochondrial genome of E. huzhuensis is 14,872 bp in length with 37 genes and two control regions. The base composition showed a distinct AT preference. Twelve protein-coding genes have a typical ATN as the start codon, and three protein-coding genes have incomplete stop codons. During the folding of tRNA genes, a total of 30 mismatches occurred, and three tRNA genes had an atypical cloverleaf secondary structure. The order of the E. huzhuensis mitochondrial genome arrangement is a new type of rearrangement in Mesostigmata. The phylogenetic analysis confirmed that the family Haemogamasidae is a monophyletic branch and does not belong to a subfamily of the Laelapidae. Our results lay the foundation for subsequent studies on the phylogeny and evolutionary history of the family Haemogamasidae.

Large gene overlaps and tRNA processing in the compact mitochondrial genome of the crustacean Armadillidium vulgare

A faithful expression of the mitochondrial DNA is crucial for cell survival. Animal mitochondrial DNA (mtDNA) presents a highly compact gene organization. The typical 16.5 kbp animal mtDNA encodes 13 proteins, 2 rRNAs and 22 tRNAs. In the backyard pillbug Armadillidium vulgare, the rather small 13.9 kbp mtDNA encodes the same set of proteins and rRNAs as compared to animal kingdom mtDNA, but seems to harbor an incomplete set of tRNA genes. Here, we first confirm the expression of 13 tRNA genes in this mtDNA. Then we show the extensive repair of a truncated tRNA, the expression of tRNA involved in large gene overlaps and of tRNA genes partially or fully integrated within protein-coding genes in either direct or opposite orientation. Under selective pressure, overlaps between genes have been likely favored for strong genome size reduction. Our study underlines the existence of unknown biochemical mechanisms for the complete gene expression of A. vulgare mtDNA, and of co-evolutionary processes to keep overlapping genes functional in a compacted mitochondrial genome.