大黄鱼、鮸鱼及美国红鱼线粒体DNA的Cytb基因序列比较

利用PCR技术对大黄鱼Pseudosciaena crocea、鮸鱼Miichthys miiuy和美国红鱼Scioenops ocellatus线粒体DNA的细胞色素b（Cyt b）基因片段进行了扩增，PCR产物直接测序，分别获得大黄鱼和美国红鱼1 140 bp的序列，鮸鱼1 125 bp的序列。通过对3种鱼的Cyt b序列的比对分析，得出3种鱼序列的相似性为91.49%；分析了3种鱼序列的碱基组成及碱基变异情况，发现3种鱼的序列差异明显，碱基替换较多，可以将Cyt b基因作为种间分子鉴定或更高分类界元遗传分析的分子标记；计算了3种鱼序列的遗传距离并构建了系统树，结果显示，鮸鱼与美国红鱼的遗传距离较近。

Sequence analysis on mitochondrial (mtDNA) Cyt b genes in Pseudosciaena crocea,Miichthys miiuy and Sciaenops ocellatus

The complete sequences of cytochrome b (Cyt b) genes in Pseudosciaena crocea and Scioenops ocellatus, and the partial sequence of Cyt b gene in Miichthys miiuy were amplified using PCR technology. The PCR products were sequenced directly. 1 140 bp fragments of Cyt b genes in P. crocea and S. ocellatus, and 1 125 bp fragment of Cyt b gene in M. miiuy were obtained. Comparing obtained sequences, the similarity of three sequences was 91.49%. Information of the base composition and the mutation sites were obtained. The difference of three sequences was obvious. The results contributed not only genetic data to economic utilization of three species but also scientific basis to analysis of genetic diversity in China Sea. Moreover, molecular phylogenetic tree of the Cyt b DNA sequences in the three species was reconstructed with the NJ method based on the inherited distance and the result showed that the inherited distance between the M. miiuy and the S. ocellatus was small.