用细胞色素 b 部分序列研究斑马鱼的分子分类与系统发育

用细胞色素b特异性引物，对长尾斑马鱼、短尾斑马鱼、豹纹斑马鱼、食蚊鱼和青石斑鱼的总DNA进行PCR扩增、克隆、测序后与Genbank数据库的团头鲂、青鲻鱼、草鱼、金桔鱼的细胞色素6基因同源序列进行序列比较。结果显示，长度为426bp的细胞色素b同源序列的平均碱基组成是：26．7％A，26．1％c．16．6％G．30．5％T，密码子第三位点的碱基组成存在较大的偏倚，G的含量仅占6．4％。长尾斑马鱼、短尾斑马鱼和豹纹斑马鱼之间细胞色素b DNA序列变异很小，相似性高于99%。NJ法构建的分子系统树表明：豹纹斑马鱼先与长尾斑马鱼聚在一起，再与短尾斑马鱼聚为一组。本研究结果支持Frankel和David等人认为豹纹斑马鱼应该是Danio rerio的一个亚种，而不是单独的一个种的观点。

The Molecular Taxonomy and Phylogeny of Zebrafish(Danio rerio) Based on the Cyt-b Partial Sequences

The taxonomy and phylogenic relationships of zebrafish were investigated by the cyt-b gene partial DNA sequence analysis of mitochondria. 426?bp of cyt-b from Danio rerio(long fin), D.rerio(short fin), D.rerio frankei, Gambusia affinis and Epinephelus awoara, respectively, were cloned and sequenced. Combined with the homologous sequences of Megalobrama amblycephala, Oryzias latipes, Ctenopharyngodon idella and Etroplus maculatus from Genebank, the aligment shows that the mean base composition for partial cyt-b is 26.7% adenine, 26.1% cytosine, 16.6% guanine, and 30.5% thymine and that the third position of the codon have a base bias (G% is only 6.4%). The sequence similarity of D.rerio(long fin), D.rerio(short fin) and D.rerio frankei is above 99%. Phylogenetic trees were constructed with Neighbor Joining method. Those results collectively indicated that D.rerio frankei might be clustered with D.rerio(long fin) first, then with D.rerio(short fin). The results support the opinion of Frankel and David that D.rerio frankei belongs to a subspecies of D.rerio and is not an individual species.