【作者】 王恒；

【导师】 苏时萍；

【作者基本信息】 安徽农业大学 ， 养殖， 2015， 硕士

【摘要】 华鳈、小鳈和黑鳍鳈,隶属于鲤形目（Cypriniformes）鲤科（Cyprinidae）鮈亚科（Gobioninae）鳈属（Sarcocheilichthys）。鳈属鱼类是中国分布较广泛的中下层水体的小型鱼类,由于其肉质细嫩、营养价值高、色泽鲜亮、体型较小、易饲养等特点,作为肉用和观赏兼用鱼类受到人们的喜爱。目前,国内外在鳈属鱼类的分类、分布、食性、饲养驯化等方面进行了零星的报道,而在其遗传结构、系统发生方面则缺乏系统的研究与报道。本研究以PCR扩增技术为基础,成功获得了华鳈、小鳈和黑鳍鳈线粒体基因组DNA的全序列,利用生物物信息学相关软件进行了基因结构和特征的比较分析,联合已知线粒体基因组的鲤科部分鱼类进行了系统发育树的构建及分析,同时采用多个线粒体DNA片段标记探讨了已知序列的五种鳈属鱼类的遗传分化和系统发生情况。研究结果为我国鳈属鱼类的分类和种间亲缘关系的研究、资源利用和保护提供提供了科学依据。主要研究结果如下:1.成功获取了鳈属三种鱼类的mtDNA全序列,三种鱼的mtDNA的长度分别为华鳈:16683 bp,小鳈:16674 bp,黑鳍鳈:16679 bp。其基因排列顺序与己知鲤科鱼类线粒体基因组一致,均包括13个蛋白质编码基因、22个tRNA基因、2个rRNA基因（12SrRNA和16SrRNA）和一个非编码区（D-Loop区）。其中tRNAGln、tRNA^Pro、tRNA^Ala、tRNA^Glu、tRNA^Cys、tRNA^Asn、tRNA^Tyr和tRNA^Ser（UCN）8个tRNA基因与ND6共9个基因由L链编码,其余28个基因则是由H链编码。2.华鳈、小鳈和黑鳍鳈的A+T含量分别为56.78%、56.34%、56.45%,平均A+T含量56.52%,明显高于G+C含量,表现出明显的A+T偏好性。A+T富集的D-Loop区,A+T含量平均值高达67.71%,明显高出全序列的平均值。3.13个蛋白编码基因除COX1以GTG为起始密码子,其余12个均以ATG为起始密码子。其中ND6基因由L链编码,H链编码其余的蛋白编码基因。三种鱼的蛋白编码基因的长度分别为:华鳈（11427 bp）、小鳈（11424 bp）、黑鳍鳈（11421 bp）。其长度差别表现在在ND2,ND4L和Cytb三个蛋白编码基因上。4.通过进化树的遗传距离可知三种鳈属鱼类中,华鳈和小鳈的亲缘关系相对较近。通过Cytb,D-Loop区所构建的进化树和全序列构建的进化树所得结果基本一致。而12S和16S两个核糖体RNA相对比较保守。本研究结果表明亲缘关系较近的鱼类选择分子标记应选择变化速率快的基因。更多还原

【Abstract】 Sarcocheilichthys sinensis,Sarcocheilichthys parvus and Sarcocheilichthys nigripinnis,belong to the Cyprinidae,Gobioninae,Sarcocheilichthys.They are small and widely distributed in China,living in the lower bodies of water.Their body color bright,size is small,easy to raise and so on,so they are the economic value of higher ornamental fishes.The research reported about Sarcocheilichthys is very few.Most of the reported is on morphological and ecological aspects.In the present study,based on the PCR amplification techniques,the complete mitochondrial DNA sequences of the S.lsinensis,S.parvus and S.nigripinnis were obtained.Comparative analysis gene structure and composition is used of biological material informatics related software.Using the mtDNA whose is known part of Cyprinidae fish construction of the evolutionary tree.At the same time,using four genes of the mtDNA to Discusses the three Cyprinidae fish genetic differentiation status quo.The results of the study are as follows:The complete mitochondrial genomes of S.sinensis,S.parvus and S.nigripinnis were 16683 bp,16674bp and 16679 bp in length,respectively.These mitochondrial genomes are consist of thirteen protein-coding genes（ND1,ND2,ND3,ND4,ND4 L,ND5,ND6,COX I,COX2、COX3,ATP6,ATP8 and Cytb）,and twenty-two tRNA genes,two rRNA genes（12SrRNA and 16SrRNA）and one noncoding region（D-Loop）.All genes were encoded on the the heavy strand（H-strand）,with the exception of eight tRNA genes(tRNA^Gln,tRNA^Ala,tRNA^Asn,tRNA^Cys,tRNA^Tyr,tRNA^Ser（UCN）,tRNA^Glu,and tRNA^Pro)and one protein-coding gene（ND6）.These genes arrangements in the three fishes mitochondrial genomes were consistent to that of others known fishes.Base composition of three fishes in the mitochondrial genome are shown AT bias.The average A+T content is 56.52%（S.sinensis:56.78%,S.parvus:56.34%,and S.nigripinnis:56.45%）which is higher than G+C.The D-loop gene is the gene which have the most A+T,the content of up to 67.71%.The remaining protein-coding genes initiate with ATG start codon except for COX I with an GTG.All protein-coding genes were encoded on the the heavy strand except for ND6.The protein-coding genes of S.sinensis,S.parvus and S.nigripinnis were 11427 bp,11424bp and 11421 bp in length,respectively,different performance in ND2,ND4 L and Cytb.Through the development of the evolutionary tree of genetic distance shows three fishes,S.sinensis and S.parvus relatively close relatives.Through the Cytb,D-Loop area constructed tree and the whole sequence evolution results are basicallyidentical.12 S and 16 S two ribosomal RNA is relatively conservative.This study shows change rate faster serve as gene marker genes of close genetic relationship of the species.更多还原