日本血吸虫组蛋白基因家族分子进化分析  

Molecular evolution of the histone gene family in Schistosoma japonicum

作　　者：沈海默[1,2] 郑琪[2] 胡薇[1] 

机构地区：[1]复旦大学生命科学学院,上海200433 [2]中国疾病预防控制中心寄生虫病预防控制所、卫生部寄生虫病原与媒介生物学重点实验室、世界卫生组织疟疾、血吸虫病和丝虫病合作中心,上海200025

出　　处：《国际医学寄生虫病杂志》2015年第2期67-73,共7页International JOurnal of Medical Parasitic Diseases

基　　金：国家科技重大专项(2009ZX10004-302)~~

摘　　要：目的 从日本血吸虫（Schistosoma japonicum）组蛋白的基因家族进化方面人手,对其基因家族的分子系统发育、共线性关系和基因倍增模式进行分析. 方法 下载3种主要致病血吸虫的全基因组序列数据及外源物种基因序列,经Blastp软件比对找出组蛋白各家族基因序列,经多序列比对构建系统进化树,计算选择压力指数（Ka/Ks）.使用基因序列与基因组比对并定位,分析同源基因的共线性关系. 结果 日本血吸虫基因组共包含组蛋白基因38条,分为5个子家族,分布在25个scaffold上.通过进化树分析共检测到基因倍增事件34次,推定基因丢失事件17次,其中H3和H4的倍增早在血吸虫物种形成之前已经完成.日本血吸虫组蛋白的倍增机制主要是DNA复制性转座,使得组蛋白在进化保守的同时还出现了更特异性的分化,从而携带更多组蛋白密码或其他修饰信息以应对较复杂的生命周期. 结论 日本血吸虫的组蛋白各子家族多数倍增事件发生在从血吸虫亚洲起源后到进入非洲分化出曼氏血吸虫之前的这段时间内,表明基因倍增是血吸虫应对环境压力的重要手段.日本血吸虫的组蛋白倍增完全来自于DNA序列的复制性转座,且净化选择占主导因素,表明增强适应性的功能分化是基因进化最主要的驱动力.Objective To investigate the molecular phylogeny,gene collinear relation and gene duplication mode of the histone gene family evolution in Schistosoma japonicum.Methods The latest version of coding gene sequences and protein sequence of three schistosomes including S.japonicum,S.mansoni and S.haematobium were downloaded from SchistoDB.The histone gene sequences were identified in Blastp and aligned in ClustalW2.1.After constructing the phylogenetic trees,the Ka/Ks value was calculated and the synteny relationships were analyzed.Results There are totally 38 histone genes in the S.japonicum genome,divided into 5 subfamilies and distributed in 25 scaffolds.By reconstruction of phylogenetic trees,34 gene duplications events and 17 gene loss events were detected.The H3 and H4 gene duplications completed even before speciation.The primary means of the gene duplication events is DNA replicative transposition,which giving histone genes more specific differentiation while keeping conservative evolution.Thus these genes can carry extra histone codes in reaction to complex life cycle.Conclusions The phylogenetic trees showed that the divergence of histone gene family was earlier than the divergence of schistosomes.However,there are 34 gene duplication and 17 gene loss events happened during the past 20 million years.It illustrates even the most conservative gene family is dynamic in evolution.Most of the duplication events took place between the time period from the schistosomes origined in Asia to divergence in Africa,demonstrating that duplication is the important instruments to response to environmental stress.Moreover,Ka/Ks values show that the functional differentiation of strengthen adaptability is the driving force behind gene evolution.

关 键 词：日本血吸虫 组蛋白 进化分析 基因倍增 

分 类 号：R383.24[医药卫生—医学寄生虫学]