Analysis of the complete mitochondrial genome sequence of Pielomastax zhengi

Abstract

The complete mitochondrial genome sequence of Pielomastax zhengi was determined by using long PCR and conserved primer walking approaches. The results showed that the entire mitochondrial genome of Pielomastax zhengi is 15 602 bp long with A+T content of 71.8%. All 37 genes are conserved in the positions observed in those of Locusta migratoria. All the genes are closely assembled by leaving 10 intergenic spacers in between. Those intergenic spacers are 47 bp in total (excluding the A+T rich region), with individual size ranges from 1 bp to 20 bp. In addition, there are a total of 52 bp overlapping sequences among 14 genes, ranging from 1-8 bp. All protein-coding genes start with a typical initiation codon in insects, ATN. Twelve protein-coding genes use the usual TAA and TAG termination codons, whereas, the ND5 genes have an incomplete termination codon (T). Except the tRNASer (AGN), whose DHU arm is absent; all the other 21 tRNA genes have typical clover-leaf secondary structures. But in Pielomastax zhengi, the secondary structures of five tRNA (tRNA(Cys), tRNA(Lys), tRNA(Phe), tRNA(Pro), tRNA(Arg)) genes can not be predicted by the conventional methods as they have only 3-4, rather than 5 base pairs in the TψC arm, while, the tRNA(Lys) and tRNA(Arg) have only 4 base pairs in the anticode arm. The predicted secondary structures of lrRNA and srRNA have 6 domains with 44 helices and 3 domains with 30 helices, respectively. The results of the rRNA secondary structure comparison showed that Pielomastax zhengi is more closely related with Locusta migratoria tibetensis than Ruspolia dubia. Like most insects, the mitochondrial genome of Pielomastax zhengi has a non-coding A+T rich region containing a polythymidine stretch, which may be involved in the replication and/or translation initiation of other genes.