Mitochondrial genome characterization of the family Trigonidiidae (Orthoptera) reveals novel structural features and nad1 transcript ends

Chuan Ma,Licui Zhang,Yeying Wang,Jianke Li

doi:10.1038/s41598-019-55740-4

Chuan Ma, Licui Zhang + Show 2 more

Open Access

https://doi.org/10.1038/s41598-019-55740-4

Copy DOI

Abstract

The Trigonidiidae, a family of crickets, comprises 981 valid species with only one mitochondrial genome (mitogenome) sequenced to date. To explore mitogenome features of Trigonidiidae, six mitogenomes from its two subfamilies (Nemobiinae and Trigonidiinae) were determined. Two types of gene rearrangements involving a trnN-trnS1-trnE inversion and a trnV shuffling were shared by Trigonidiidae. A long intergenic spacer was observed between trnQ and trnM in Trigonidiinae (210−369 bp) and Nemobiinae (80–216 bp), which was capable of forming extensive stem-loop secondary structures in Trigonidiinae but not in Nemobiinae. The anticodon of trnS1 was TCT in Trigonidiinae, rather than GCT in Nemobiinae and other related subfamilies. There was no overlap between nad4 and nad4l in Dianemobius, as opposed to a conserved 7-bp overlap commonly found in insects. Furthermore, combined comparative analysis and transcript verification revealed that nad1 transcripts ended with a U, corresponding to the T immediately preceding a conserved motif GAGAC in the superfamily Grylloidea, plus poly-A tails. The resultant UAA served as a stop codon for species lacking full stop codons upstream of the motif. Our findings gain novel understanding of mitogenome structural diversity and provide insight into accurate mitogenome annotation.

Highlights

The typical mitochondrial genome of insects is a circular molecule ranging in size from 15 kb to 18 kb[1]
All six mitogenomes encoded the typical set of 37 genes for insects, i.e. 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, and two ribosomal RNA (rRNA) genes
Nine PCGs and 11 tRNA genes were encoded on the majority strand while the other genes were on the minority strand

Summary

Introduction

The typical mitochondrial genome (mitogenome) of insects is a circular molecule ranging in size from 15 kb to 18 kb[1]. Only the complete mitogenome of Trigonidium sjostedti (Chopard, 1925)[6] from Trigonidiinae has been sequenced within the whole family It shows unique structural features, including www.nature.com/scientificreports the occurrence of two types of gene rearrangements: an inversion of trnN-trnS1-trnE encoded on the majority strand to trnE-trnS1-trnN on the minority strand and a shuffling of trnV to the position between rrnS and the control region. There is an urgent need of mitogenome sequencing of Trigonidiidae, which can shed light on the phylogenetic distribution and evolutionary origin of these rearrangements and other features To fill this gap, three representative mitogenomes (Dianemobius fascipes (Walker, 1869), D. furumagiensis (Ohmachi & Furukawa, 1929), and Polionemobius taprobanensis (Walker, 1869)) from Nemobiinae and three (Homoeoxipha nigripes Xia & Liu, 1992, Natula pravdini (Gorochov, 1985), and Svistella anhuiensis He, Li & Liu, 2009) from Trigonidiinae were sequenced and annotated in this study. We provide a means to ensure accurate annotation of nad[1] stop codons for Grylloidea

Methods

Results

Conclusion