| Abstract: | Deep-sea organisms survive in an extremely harsh environment.There must be some genetic adaptation mechanisms for them.We systematically characterized and compared the complete mitochondrial genome(mitogenome) of a deep-sea crab(Chaceon granulates) with those of shallow crabs.The mitogenome of the crab was 16 126 bp in length,and encoded 37 genes as most of a metazoan mitogenome,including 13 protein-coding genes(PCGs),22 transfer RNA(tRNA) genes,and 2 ribosomal RNA(rRNA) genes.The gene arrangement and orientation was conserved in the crabs.However,a unique mitogenome element regulator,the origin of light-strand replication(O L),was firstly predicted in the present crab mitogenome.In addition,further positive selection analysis showed that two residues(33 S in ND3 and 502 I in ND5) in C.granulates mitogenome were positively selected,indicated the selective evolution of the deep-sea crab.Therefore,the mitogenome of deep-sea C.granulates showed a unique O_L element and positive selection.These special features would influence the mitochondrial energy metabolism,and be involved in the adaptation of deepsea environment,such as oxygen deficits and low temperatures. |
