鲈形目TLR1和TLR9基因的选择压力分析  

Analysis of Selection Pressure on TLR1 and TLR9 Genes in Perciformes

作　　者：刘兴 高波[2] 吉红九[2] 贾超峰[2] 祝斐[2] 孟乾 陈淑吟[2] 张志勇[2] 徐士霞[1] Liu Xing;Gao Bo;Ji Hongjiu;Jia Chaofeng;Zhu Fei;Meng Qian;Chen Shuyin;Zhang Zhiyong;Xu Shixia(School of Life Sciences,Nanjing Normnal University,Jiangu Provincial Key Laboratory of Biodiversity,Nanjing 210023,China;Marine Fisheries Research Institute of Jiangyu Province,Jiangsu Key Laboratory for Genetics and Breeding of Marine Fishes,Nantong 226007,China)

机构地区：[1]南京师范大学生命科学学院,江苏省生物多样性重点实验室,江苏南京210023 [2]江苏省海洋水产研究所,江苏省海水鱼类遗传育种重点实验室,江苏南通226007

出　　处：《南京师大学报（自然科学版）》2022年第3期68-78,共11页Journal of Nanjing Normal University(Natural Science Edition)

基　　金：江苏省农业重大新品种创制项目(PZCZ201744);江苏省种业振兴“揭榜挂帅”项目(JBGS[2021]034)。

摘　　要：鲈形目(Perciformes)是鱼类中物种丰富度最高的一个目,分布在多个水域,在渔业经济发展中占据着重要地位.然而,高密度的养殖模式加剧了病原微生物引起的鱼类病害.Toll样受体(Toll-like receptors,TLRs)是先天免疫中的重要蛋白质分子,在病毒以及细菌防御中起重要作用.本文以TLR1和LTR9为候选基因,共下载了鲈形目17个代表物种的同源序列,通过进化分析探讨该目物种先天性免疫的分子进化基础.选择压力分析发现TLR1、TLR9基因中分别有16和8个正选择位点被两种方法同时检测到,且86%的位点位于蛋白质富含亮氨酸重复序列(Leucine rich repeat,LRR)结构域.上述结果提示鲈形目物种面临较高的病原微生物感染的挑战,而这些正选择位点可能导致基因进化出重要的功能改变以抵抗病原体的侵袭.另外,Free-ratio以及Branch-site模型检测发现基因的正选择具有物种特异性,如TLR1在鲷科的最近共同祖先支以及鲈科最近共同祖先支等受到显著正选择,TLR9也在鲷科的最近共同祖先支受到显著正选择,且这些谱系被报道经常受到病原体的威胁,因此,鲈形目多个谱系受到正选择可能是在长期抵抗病原微生物侵袭中进化的结果.以上研究结果表明,在长期抵御病原微生物过程中,鲈形目物种的TLR1、TLR9基因可能发生了适应性功能改变.The Perciformes is an order with the highest species richness in fish,distributed in many waters,and plays an essential role in developing the fishery economy.However,the high-density culture mode aggravates the fish diseases caused by pathogenic microorganisms.Toll-like receptors(TLRs)are essential proteins in innate immunity and play an important role in the defense against bacterial or viral infections.In this paper,TLR1 and LTR9 were used as candidate genes,and the homologous sequences of 17 representative species of Perciformes were downloaded.The molecular evolutionary basis of innate immunity of this species was discussed by evolutionary analysis.Selective pressure analysis showed that the three methods simultaneously detected 16 and 8 positive selection sites in TLR1 and TLR9,respectively.86%of sites were located in the Leucine rich repeat(LRR)domain.These results suggest that Perciformes species face the challenge of high pathogenic microbial infection.These positive selection sites may lead to critical functional changes in gene evolution to resist pathogen invasion.In addition,free-ratio and branch-site models found that positive selection of genes was species-specific.For example,TLR1 is significantly positively selected in the last common ancestor(LCA)branch of Sparidae and Percidae,and TLR9 is also significantly positively selected in the last common ancestor branch of Sparidae.These lineages are often reported to be threatened by pathogens.Therefore,the positive selection of multiple Perciformes lineages may result from evolution in long-term resistance to pathogenic microorganisms.The above results indicated that TLR1 and TLR9 of Perciformes species may have changed their adaptive functions during the long-term resistance to pathogenic microorganisms.

关 键 词：鲈形目 TLR1 TLR9 适应性进化 先天性免疫 

分 类 号：Q953[生物学—动物学]