中国不同种拟钉螺CO1基因序列差异分析及其系统学初探

目的研究中国拟钉螺线粒体CO1基因的差异并初步探讨其系统发生。方法收集4省7地拟钉螺标本,抽提基因组DNA,PCR扩增线粒体CO1基因,扩增产物纯化后进行序列测定,所测序列用Kimura双参数法计算遗传距离,NJ和UPGMA法构建系统进化树。结果PCR扩增得到大小约700bp的片段。遗传距离显示:台湾邱氏拟钉螺与湖北钉螺滇川亚种亲缘关系最近距离为0.124,而与其余6种拟钉螺遗传距离较远,遂将其分为两组。6种拟钉螺组内距离为0.127,两组间距离为0.179。两种方法构建进化树拓扑结构基本一致。台湾邱氏拟钉螺与湖北钉螺滇川亚种聚为一支,其余6种拟钉螺位于另一支。结论台湾邱氏拟钉螺应归入湖北钉螺,钉螺与拟钉螺属单源进化。中国不同种拟钉螺CO1基因存在差异。

Sequence difference analysis of CO1 gene from different species of Tricula in China and their phylogenetic relationship

To understand the sequence difference of CO1 gene from different species of Tricula in China and preliminarily to analyze their phylogenetic relationship,snails were collected for study from 7 different area distributed in four provinces of China.The genomic DNAs were extracted,and the mitochondial CO1 gene fragments were amplifies with PCR.After purification,the amplified products were sequenced,and the Program MEGA3.1 was used for sequence analysis.Genetic distances were computed with Kimura-two parameter model and phylogenetic tree was reconstructed with NJ and UPG methods respectively.The experimental results showed that a gene fragment with molecular size about 700 bp were obtained after PCR amplifications.Results of the genetic distances revealed that Tricula chiui of Taiwan was mostly close to Oncomelania hupensis robertsoni of Hubei province with a distance between these two groups of 0.124,but the genetic distances with other 6 species of snails were quite farther,thus clustering into two distinct groups.The distance between these two groups was 0.179,and among these 6 species of Tricula it was 0.127.Meanwhile,the topology constructed by two methods of phylogenetic trees was rather similar,in which it was showed that Tricula chiui and O.hupensis robertsoni located in one class,and the other 6 species assembled in the other one.It is concluded that Tricula chiui should be sorted to Oncomelania hupensis,but these two species are monophylectic,there are diversities in the CO1 gene among different species of Tricula in China.