The first complete mitogenome of the South China deep-sea giant isopodBathynomussp. (Crustacea: Isopoda: Cirolanidae) allows insights into the early mitogenomic evolution of isopods.
In this study, the complete mitochondrial (mt) genome sequence of the South China deep-sea giant isopodBathynomussp. was determined, and this study is the first to explore in detail the mt genome of a deep-sea member of the order Isopoda. This species belongs to the genusBathynomus, the members of which are saprophagous residents of the deep-sea benthic environment; based on their large size,Bathynomusis included in the "supergiant group" of isopods. The mt genome ofBathynomussp. is 14,965 bp in length and consists of 13 protein-coding genes, two ribosomal RNA genes, only 18 transfer RNA genes, and a noncoding control region 362 bp in length, which is the smallest control region discovered in Isopoda to date. Although the overall genome organization is typical for metazoans, the mt genome ofBathynomussp. shows a number of derived characters, such as an inversion of 10 genes when compared to the pancrustacean ground pattern. Rearrangements in some genes (e.g.,cob,trnT,nad5,andtrnF) are shared by nearly all isopod mt genomes analyzed thus far, and when compared to the putative isopod ground pattern, five rearrangements were found inBathynomussp. Two tRNAs exhibit modified secondary structures: The TΨC arm is absent fromtrnQ, andtrnClacks the DHU. Within the class Malacostraca,trnCarm loss is only found in other isopods. Phylogenetic analysis revealed thatBathynomussp. (Cymothoida) andSphaeroma serratum(Sphaeromatidea) form a single clade, although it is unclear whether Cymothoida is monophyletic or paraphyletic. Moreover, the evolutionary rate ofBathynomussp. (dN/dS [nonsynonymous mutational rate/synonymous mutational rate] = 0.0705) is the slowest measured to date among Cymothoida, which may be associated with its relatively constant deep-sea environment. Overall, our results may provide useful information for understanding the evolution of deep-sea Isopoda species.
The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences Institute of Hydrobiology Chinese Academy of Sciences Wuhan Hubei China; University of Chinese Academy of Sciences Beijing China.
Yanjun
0000-0002-6464-7466
Y
Shen
Institute of Oceanology Chinese Academy of Sciences Qingdao China.
Qi
Q
Kou
The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences Institute of Hydrobiology Chinese Academy of Sciences Wuhan Hubei China; University of Chinese Academy of Sciences Beijing China.
Zaixuan
Z
Zhong
Institute of Oceanology Chinese Academy of Sciences Qingdao China.
Xinzheng
X
Li
Institute of Deep-sea Science and Engineering Chinese Academy of Sciences Sanya China.
Lisheng
L
He
The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences Institute of Hydrobiology Chinese Academy of Sciences Wuhan Hubei China.
Shunping
S
He
The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences Institute of Hydrobiology Chinese Academy of Sciences Wuhan Hubei China.
Xiaoni
X
Gan
Bathynomus; Isopoda; deep sea; gene rearrangement; mitochondrial genome