【作者】 丁小雷；

【导师】 邓凤姣；

【作者基本信息】 武汉大学 ， 细胞生物学， 2003， 硕士

【摘要】 我国近海海域包括渤、黄、东、南四海，地跨温带、亚热带和热带海区，海洋双壳纲贝类极为丰富，绝大部分种类具有很高的经济价值。近十几年来，近海贝类养殖业发展迅速，已成为沿海地区海水养殖的重要支柱产业之一。然而有关海洋经济贝类各科属种间的分子系统发育关系研究报道甚少。本研究测定了该纲11个不同种(分属于5科、6属)的核糖体18S基因部分序列及转录间隔区1(ITS1)全序列，所得序列已全部登录到GenBank数据库。结果表明，该序列在种间存在很高的多态性，长度从558 bp到784 bp不等，碱基差异百分比在3.8％～60.4％之间，种间ITS1序列同源性很低，有片段的插入与缺失。不同种间的18S基因部分序列同源性相对较高，差异主要表现在碱基的转换。用邻接法(NJ)构建了14个种的18S部分序列(约240 bp)的系统发育树，首次从分子水平上确定这些种在该纲中的分类地位，其系统关系与传统形态学分类结果基本一致。对取自四个不同地域群体的马氏珠母贝(Pinctada martensi)个体的18S-ITS1序列进行了测定，该序列在种内个体间的差异百分比在0.6％～1.9％之间。分析指出：18S基因可以作为双壳纲动物高阶元阶系统发育的分子标记；ITS1序列种间变化很大，可以应用于该纲物种的分类及鉴别，在亲缘关系相近种及种内变异相对较小，但核苷酸变异位点信息量丰富，可用于属内种间、亚种和群体间的遗传多样性研究。 另外，本论文运用27个10碱基随机引物对不同地域的马氏珠母贝种群间交配获得的子一代六个群体进行了RAPD分析。结果表明，群体间交配子代的Shannon多样性指数分别高于群体内交配所得子代的指数。最后讨论了不同地域之间进行马氏珠母贝育种及遗传多样性保护工作的可行性。更多还原

【Abstract】 Bivalves constitute a dominant and divers group of marine animals in our country. Most of them are of major commercial important species, and studies on their genetic diversity are necessary for the sustainable exploitation and conservation of these bioresources. The objective of the present study is to explore the feasibility of using the ribosomal DNA as a molecular marker for studying the interspecific phylogenetic relationship and intraspecific genetic variations among bivalves. The 18S-ITS1 sequences of 11 species at differing taxonomic levels were determined. The sequences were found to exhibit a high degree of length polymorphism among different species, ranging from 558 bp (Chlamys farreri) to 784 bp in (Ostrea rivulahs), mainly resulting from the variation of ITS1. The percent divergence of sequences ranged from 3.8% to 60.4%. The NJ (neighbor-joining) tree inferred from 18S fragment of 14 species agree with the previous based on morphologies and chemical analysis well. The sequence was found to vary among 4 geographical sites of Pinctada martensi, ranging from 0.6% to 1.9%. The variations involved substitutions, transversion as well as insertions and deletions among them in P.martensi. All these results show that ITS1 is highly divergent among different species of bivalves and could be used in classification and distinguishing closely related species, and also could be used for molecular systematic studies at relative species, subspecies and population levels.Pinctata martensi is one of the most important aquacultural seashells in the southeast of China. Wild individuals were collected from Sanya (Hainan province), Beihai (Guangxi province) and Daya Bay (Guangdong province) randomly, then mated and cultured in the same condition. In order to get a deep understanding of it and improve efficiency of breeding by marker-assisted selection, we using 27 primers tested different filial populations by RAPDtechnique. The results showed that the diversity Shannon index of filial population mated from inter-populations was higher than filial populations mated from inner-populations. Then we analyzed the feasibility of breeding from two different areas.更多还原