Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, Sanya, China.
University of Chinese Academy of Sciences, Beijing, China.
PLoS One. 2020 Nov 30;15(11):e0242541. doi: 10.1371/journal.pone.0242541. eCollection 2020.
Phymorhynchus is a genus of deep-sea snails that are most distributed in hydrothermal vent or cold seep environments. In this study, we presented the complete mitochondrial genome of P. buccinoides, a cold seep snail from the South China Sea. It is the first mitochondrial genome of a cold seep member of the superfamily Conoidea. The mitochondrial genome is 15,764 bp in length, and contains 13 protein-coding genes (PCGs), 2 rRNA genes, and 22 tRNA genes. These genes are encoded on the positive strand, except for 8 tRNA genes that are encoded on the negative strand. The start codon ATG and 3 types of stop codons, TAA, TAG and the truncated termination codon T, are used in the 13 PCGs. All 13 PCGs in the 26 species of Conoidea share the same gene order, while several tRNA genes have been translocated. Phylogenetic analysis revealed that P. buccinoides clustered with Typhlosyrinx sp., Eubela sp., and Phymorhynchus sp., forming the Raphitomidae clade, with high support values. Positive selection analysis showed that a residue located in atp6 (18 S) was identified as the positively selected site with high posterior probabilities, suggesting potential adaption to the cold seep environment. Overall, our data will provide a useful resource on the evolutionary adaptation of cold seep snails for future studies.
Phymorhynchus 是深海蜗牛的一个属，主要分布在热液喷口或冷渗环境中。在这项研究中，我们展示了来自南海冷渗蜗牛 P. buccinoides 的完整线粒体基因组。这是 Coneoidea 超科冷渗成员的第一个线粒体基因组。线粒体基因组长 15764bp，包含 13 个蛋白质编码基因（PCGs）、2 个 rRNA 基因和 22 个 tRNA 基因。这些基因编码在正链上，只有 8 个 tRNA 基因编码在负链上。13 个 PCGs 的起始密码子为 ATG，使用 3 种终止密码子，TAA、TAG 和截短的终止密码子 T。Coneoidea 的 26 个物种中的所有 13 个 PCGs 都具有相同的基因排列顺序，而一些 tRNA 基因发生了移位。系统发育分析表明，P. buccinoides 与 Typhlosyrinx sp.、Eubela sp. 和 Phymorhynchus sp. 聚在一起，形成了 Raphitomidae 分支，具有较高的支持值。阳性选择分析表明，位于 atp6（18S）的一个残基被鉴定为具有高后验概率的阳性选择位点，表明潜在的适应冷渗环境。总的来说，我们的数据将为未来研究冷渗蜗牛的进化适应提供有用的资源。
