The deep-sea environment is characterized by darkness, hypoxia, and high hydrostatic pressure. Mitochondria play a vital role in energy metabolism; thus, they may endure the selection process during the adaptive evolution of deep-sea organisms. In the present study, the mitogenome of Phymorhynchus sp. from the Haima methane seep was completely assembled and characterized. This mitogenome is 16,681 bp in length and contains 13 protein-coding genes, 2 rRNAs, and 22 tRNAs. The gene order and orientation were identical to those of most sequenced conoidean gastropods. Some special elements, such as tandem repeat sequences and AT-rich sequences, which are involved in the regulation of the replication and transcription of the mitogenome, were observed in the control region. Phylogenetic analysis revealed that Conoidea is divided into two separate clades with high nodal support. Positive selection analysis revealed evidence of adaptive changes in the mitogenomes of deep-sea conoidean gastropods. Eight residues located in atp6, cox1, cytb, nad1, nad4, and nad5 were determined to have undergone positive selection. This study explores the adaptive evolution of deep-sea conoidean gastropods and provides valuable clues at the mitochondrial level regarding the exceptional adaptive ability of organisms in deep-sea environments.

中文翻译：

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Phymorhynchus sp. 的完整有丝分裂基因组。(Neogastropoda, Conoidea, Raphitomidae) 提供对 Conoidea 深海适应性进化的见解

深海环境的特点是黑暗、缺氧、静水压高。线粒体在能量代谢中起着至关重要的作用；因此，它们可能会在深海生物的适应性进化过程中经受选择过程。在本研究中，Phymorhynchus 的有丝分裂基因组sp. 来自海马的甲烷渗漏被完全组装和表征。该有丝分裂基因组的长度为 16,681 bp，包含 13 个蛋白质编码基因、2 个 rRNA 和 22 个 tRNA。基因顺序和方向与大多数测序的锥状腹足动物相同。在控制区观察到一些特殊的元件，如串联重复序列和富含AT的序列，它们参与调节有丝分裂基因组的复制和转录。系统发育分析表明，Conoidea 分为两个独立的进化枝，具有高节点支持。正选择分析揭示了深海锥状腹足动物有丝分裂基因组适应性变化的证据。八个残基位于atp6 , cox1 , cytb , nad1、nad4和nad5被确定为经历了正选择。这项研究探索了深海锥状腹足动物的适应性进化，并在线粒体水平上提供了有关深海环境中生物的特殊适应性能力的宝贵线索。