鲇细胞 b基因序列变异及遗传多样性分析

从４个种群的鲇（Ｓｉｌｕｒｕｓａｓｏｔｕｓ）线粒体ＤＮＡ（ｍｉｔｏｃｈｏｎｄｒｉａｌＤＮＡ，ｍｔＤＮＡ）扩增出约５００ｂｐ的细胞色素ｂ基因，经ＣｌｕｓｔａｌＸ同源排序后得４００ｂｐ序列。用ＰｏｐＧｅｎ３２软件计算遗传距离和遗传一致度。１７个个体间的遗传 距离的变化范围为０～０．０２１１，遗传一致度的变化范围为１～０．９７９１。结果显示，在长江上游的支流中，雅砻江种群在该基因片段上基本不存在变异，在被分析的４个个体中，其细胞色素ｂ基因的序列完全一致；岷江种群和乌江种群在该基因片段上有一定的变异。沅江上游的贘阳河种群在该基因片段上基本不存在变异，在被分析的５个个体中，其细胞色素ｂ基因的序列完全一致。但各个种群间在该基因片段上差异较大。在４个种群的鲇Ｃｙｔｂ基因比较分析的基础上，构建了遗传关系聚类图，雅砻江、岷江、乌江、贘阳河４个种群各聚为一支后，雅砻江和岷江２个种群再聚为一支，乌江和贘阳河２个种群再聚为另一支。

Genetic Diversity of Silurus asotus on Mitochondrial Cytochrome b Gene Sequence

The 500 bp fragments of cytochrome b gene were obtained by PCR method from the mitochondrial DNA of Silurus merdionalis from four species groups, and a mitochondrial cytochrome b DNA of 400bp sequence was successfully sequenced by Clustal X nomologous sequence analysis. The three upper branch groups are from Ya- longjiang river in Sichuan Province, Minjiang river in Sichuan Province, and Wujiang river in Guizhou Province respectively. The middle branch group is from wuyanghe river in Guizhou Province. The genetic identity, from 1 0. 9791 among groups, and the genetic distance from 0 -0.0211 among groups, were calculated by PopGen32. The results showed that there was no variation on the gene of the two species groups fromYalongjiang river in Sichuan Province and wuyanghe river in Guizhou Province, there were some variations on the gene of the two species groups from Minjiang river in Sichuan Province and Wujiang river in Guizhou Province. But there were some variations among the four species groups. The dendrogram of genetic relationship constructed by PopGen32 indicates that they are divided into four branches, in which groups from Yalongjiang river in Sichuan and Minjiang river in Sichuan are clustered together as one branch, groups from Wujiang river in Guizhou Province and wuyanghe river in Guizhou Province are another.