Abstract: Pancreatic ribonuclease 10，which is encoded by RNase10, is a vertebrate-specific reproductive enzyme. Studies of RNase10 mainly focus on physiological function, while molecular evolution is not commonly addressed. Here, 26 RNase10s from 24 available genomic sequences of Cetartiodactyla species were identified. Surprisingly, gene duplications were mostly detected in the Artiodactyla species of Bubalus bubalis and Sus scrofa, whereas only a single RNase10 was observed in the other 22 species examined. Phylogenetic analyses with diverse methods resulted in a well-resolved phylogeny, dividing Cetacea into Odontoceti and Mysticeti, supporting monophyly of Tylopoda and Suina. The signature motif CKXXNTF has been changed and the isoelectric point (pI) is lower than that for any other RNASE A members, raising the possibility that Cetartiodactyla RNase10 may lack ribonuclease or antibacterial activities. Moreover, 13 positive sites were detected. Two of the 13 sites are observed to near the structure Cysteine of the RNase10 enzyme. Our results demonstrate the evolutionary mechanism and establishe an important theoretical foundation for future functional assays in Cetartiodactyla RNase10.

Key words: Cetartiodactyla, Gene duplication, Isoelectric point, Pancreatic ribonuclease 10 (RNase10), Phylogenetic, Positive selection

摘要： 核糖核酸酶10由RNase10序列编码，是脊椎动物特有的生殖酶,其研究主要集中在生理功能，系统的分子进化研究相对甚少。本文，我们基于24个鲸偶蹄目代表物种的基因组分析，共获得26条RNase10序列。在偶蹄目的印度水牛和野猪中首次检测到RNase10发生基因复制，而其它22个物种均为单个基因。系统发育分析揭示鲸目的齿鲸亚目和须鲸亚目形成单系；偶蹄目的反刍亚目最先分歧，猪次目和胼足亚目形成单系。具有核糖核酸酶活性的保守功能区“CKXXNTF”发生了改变，等电点显著低于RNASE A的典型成员，揭示鲸偶蹄目RNase10可能丢失了RNASE A具有的核糖核酸活性和抗菌活性。另外，选择压力分析共检测到13个正选择位点，其中2个位点在结构半胱氨酸附近。总之，我们基于基因组分析深入揭示了鲸偶蹄目RNase10的分子进化机制，解开了鲸偶蹄目RNase10的分子进化之谜，为今后开展RNase10功能研究奠定了理论基础。

关键词: 核糖核酸酶10, 鲸偶蹄目, 基因复制, 等电点, 系统发育, 正选择