Complete Mitochondrial Genome of Teleogryllus emma (Orthoptera: Gryllidae) with a New Gene Order in Orthoptera

The complete sequence of Teleogryllus emma mitochondrial genome was determined using long PCR and conserved primer walking approaches. The results showed that the entire mitochondrial genome of T. emma was 15 660 bp in length, with an A+T content of 74.3%. The most distinct feature of this mtDNA is that the tRNA genes of Glutamic acid, Serine and Asparagine are located in the minor strand, and thus constitutes the third type of gene order of mitochondria in Orthoptera. The intergenic spacers range from 1 to 24 bp in size, totaling 73 bp. A total of 54 overlapping nucleotides exist among 14 genes, ranging from 1 to 11 bp in size. The TAA and TAG codons are used as stop codons in all the protein coding genes (PCGs) except COII, ND5 and ND4. The COI gene has an unusual start codon, TTA, instead of ATN or NTG. Most of the tRNA genes, except tRNASer (AGN), form typical secondary structures. An A+T rich region of T. emma mitochondrial genome with 940 bp in length exists as an ubiquitous secondary structure found in the Orthoptera and other orders of Insecta, such as Diptera, Lepidoptera, Hymenoptera, but not in Collembola, which is considered the basal group of Insecta.