不同地理种群鳄蜥tlr4基因遗传多样性及SNPs分布特点分析  

Genetic Diversity and SNPs Distribution Characteristics of tlr4 Gene in Different Geographic Populations of the Chinese Crocodile Lizard

作　　者：莫大颖 江海英 黄铭威 武正军[1,2] 陈金平 MO Da-Ying;JIANG Hai-Ying;HUANG Ming-Wei;WU Zheng-Jun;CHEN Jin-Ping(Key Laboratory of Ecology and Environmental Protection of Rare and Endangered Animals and Plants,Ministry of Education,Guilin 541004;Guangxi Key Laboratory of Endangered Animal Ecology,Guilin 541004;Guangdong Institute of Applied Biological Resources,Guangzhou 510260,China)

机构地区：[1]珍稀瀕危动植物生态与环境保护教育部重点实验室,桂林541004 [2]广西濒危动物生态学重点实验室,桂林541004 [3]广东省生物资源应用研究所,广州510260

出　　处：《动物学杂志》2019年第6期845-859,共15页Chinese Journal of Zoology

基　　金：广州市科技计划项目重点项目专题(No.201804020080);国家自然科学基金项目(No.31760623)

摘　　要：Toll样受体(TLRs)是一类识别病原体中高度保守的病原相关分子模式(PAMPs)的蛋白家族,在启动先天性免疫中具有重要作用。人类toll样受体4基因(toll4)的点突变与许多疾病有关,如呼吸道合胞病毒感染、动脉粥样硬化、疟疾等,并且这种点突变往往具有种族分布特异性。鳄蜥(Shinisaurus crocodilurus)是一种古老的爬行动物,属于国家Ⅰ级保护野生动物,由于其遭受非法捕杀、栖息地破坏等人为干扰,目前数量极其稀少。近年来,鳄蜥因疾病造成大量的死亡,且这种疾病的分布具有种群差异性,不同种群往往疾病症状也不同,可能是因不同的病原体感染引起的。我们设想toll4基因的点突变在鳄蜥种群之间可能具有分布的差异性,以适应不同的当地病原体。因此,本文利用PCR产物直接测序和生物信息学分析法初步探索鳄蜥toll4基因的遗传多样性以及单核苷酸多态性(SNPs)的分布特点,验证该基因的点突变是否具有种群特异性分布特点,以及预测其氨基酸替换是否对蛋白质结构和功能产生影响。结果获得的扩增片段长为1694 bp,在5个种群52条序列中(登录号MN380726~MN380777),共发现27个突变位点,导致9个氨基酸替换,其中3个氨基酸替换被预测为影响蛋白质的结构和功能。27个点突变中有12个只分布在单个种群,4个分布无种群特异性,即每个种群中均有野生型和突变型,其余11个点突变的突变型分布在2或3个种群不等。研究表明,鳄蜥toll4基因遗传多态性在各种群间不一致,且点突变具有种群特异性分布特征,反映不同地理种群遭受不同的病原压力。Toll-like receptors(TLRs)are a family of proteins that recognize highly conserved pathogen-related molecular patterns(PAMPs)in pathogens,and play an important role in initiating innate immunity.Point mutations in the human tlr4 gene have been shown to be associated with many diseases,such as respiratory syncytial virus infection,atherosclerosis,malaria,etc.,and these mutations are often racially specific.The Chinese Crocodile Lizard(Shinisaurus crocodilurus)is an ancient reptile which belongs to the national first-class protection animal.Due to anthropogenic disturbance,such as illegal hunting and habitat destruction,the number of the Chinese Crocodile Lizard is extremely rare.In recent years,a large number of death of the Chinese Crocodile Lizard has been caused due to various diseases,and the diseases are different among different populations,often with different disease symptoms,which are possibly caused by different pathogens.We predict that point mutations in the tlr4 gene might be distributed differently among the Chinese Crocodile Lizard populations to accommodate different local pathogens.Therefore,the aim of this study is to preliminarily explore the genetic diversity of tlr4 gene and the distribution characteristics of SNPs in the Chinese Crocodile Lizard by using PCR product direct sequencing and bioinformatics analysis,and to verify whether the point mutation on the gene has the population-specific distribution,and to test whether its non-synonymous substitution has an impact on the structure and function of protein.The amplified fragment length was 1694 bp(Fig.1),and the genetic diversity of each population was different,with Linzhouding population the highest and Dayaoshan population the lowest,which corresponds to the largest population of Linzhouding and the smallest population of Dayaoshan(Table 1).A total of 27 point mutations were found in 52 individuals(GenBank accession:MN380726﹣MN380777)from five populations,leading to nine non-synonymous substitutions(Table 2),three of which were predicte

关 键 词：TOLL样受体4 遗传多样性 点突变 鳄蜥 

分 类 号：Q953[生物学—动物学]