Complete mitochondrial genome of Episymploce splendens (Blattodea: Ectobiidae): A large intergenic spacer and lacking of two tRNA genes

Abstract

The complete mitochondrial genome of Episymploce splendens, 15,802 bp in length, was determined and annotated in this study. The mito-genome included 13 PCGs, 20 tRNAs and 2 rRNAs. Unlike most typical mito-genomes with conservative gene arrangement and exceptional economic organization, E. splendens mito-genome has two tRNAs (tRNA-Gln and tRNA-Met) absence and a long intergenic spacer sequence (93 bp) between tRNA-Val and srRNA, showing the diversified features of insect mito-genomes. This is the first report of the tRNAs deletion in blattarian mito-genomes and we supported the duplication/random loss model as the origin mechanism of the long intergenic spacer. Two Numts, Numt-1 (557 bp) and Numt-2 (975 bp) transferred to the nucleus at about 14.15 Ma to 22.34 Ma, and 19.19 Ma to 24.06 Ma respectively, were found in E. splendens. They can be used as molecular fossils in insect phylogenetic relationship inference. Our study provided useful data for further studies on the evolution of insect mito-genome.

Comparative mitochondrial genome brings insights to slight variation in gene proportion and large intergenic spacer and phylogenetic relationship of mudskipper species.

“…4). These results were also observed in the literature (Yan et al, 2022 andGong et al, 2019). The most used amino acid was Leu (13,75%), Pro (9,78%), Ser (8,48%) and Thr (7,51%) and the least used were Glu (2,89%), Trp (2,72%), Asp (2,32%), Arg (2,27%) and Cys (1,94), respectively (Fig.…”

The first complete mitochondrial genome ofSphaeniscus atilius(Walker, 1849) (Diptera: Tephritidae) and implications for the phylogenetic relationships of Tephritidae

“…It has the typical organization and composition of an insect mitochondrion, containing 37 genes, including 13 protein-coding genes (PCGs), 22 tRNA genes, and 2 rRNA genes, which was consistent with those described in other subfamily Tephritoidea insects, such as Bactrocera carambolae [22], Zeugodacus cucurbitae [24], Dacus haikouensis [40]. The nucleotide composition of all regions showed a strong AT bias [41], as seen in other insects [18,19,42]. The AT-skew of the full mitogenome is positive (0.02), while the GC skew is negative (-0.16), indicating that the content of bases C is higher than that of G, and A is higher than T in the whole genome.…”

“…Generally, the duplication/random loss model and slipped-strand mispairing have been used to explain the origin of mitogenome intergenic spacers [16,45]. Whether these long spacer regions were functional was controversial [18].…”

“…Generally, the typical insect mitochondrial genome is a highly conserved circular molecule ranging in size from approximately 14 to 40 kbp, encoding a fixed set of 37 genes, including 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, and a control region (CR) or the A+T-rich region [14,15], with only a few exceptions. For example, long gene intergenic spacers, gene rearrangements, and gene loss have also been reported in different orders of insects [16][17][18].…”

“…Partial mitochondrial gene sequences have become a preferred approach for inferring phylogenetic and molecular systematic studies in several insect groups, such as Arma custos and Picromerus lewisi (Hemiptera) [19], Episymploce splendens (Blattodea) [18], and Haematopinus tuberculatus (Psocodea) [20], Coomaniella copipes, Coomaniella dentata, and Dicerca corrugate (Coleoptera) [21], including the Tephritidae family (Ceratitis fasciventris [9], Bactrocera carambolae [22],…”