3个水域黄鳍鲷线粒体DNA D-loop基因序列多态性研究

利用PCR技术扩增海南海口市、福建厦门市和广东珠海市3个地理群体海捕黄鳍鲷线粒体D-loop基因片段，测定了该基因片段580bp序列。结果发现，3个地理群体内和群体间都存在丰富的DNA序列多态性，共检测到33个多态性核苷酸位点(5．7％)，24个个体具有22种单倍型(haplotype)。UPGMA法构建的分子系统树中，海南群体内所有的单倍型聚成一支，福建与广东的单倍型混杂在一起，聚成一支。从序列差异的分析中得出，海南群体与福建和广东群体的亲缘关系较远；福建群体和广东群体亲缘关系较近。

Polymorphism study of the mitochondrial DNA D-loop gene sequences from Sparus latus

580bp mitochondrial D-loop gene segments of Sparus latus caught in sea from Haikou (Hainan Province), Xiamen (Fujian Province), Zhuhai (Guangdong Province) were amplified with PCR technique and sequenced. The accession numbers are from AF549503 to AF549524 in GenBank. High genetic polymorphism in the three stocks was examined. It was found that 33 nucleotide sites (5.7%) were variable in mtDNA D-loop gene segments, and there were 22 haplotypes in 24 individuals. According to the sequences of mtDNA D-loop gene segments, the genetic distances of inter-and intrapopulafion of three stocks were calculated using twoparameter method of Kimura, M(1980). The genetic distances were 1.34 %, 1.34 % and 1.41% in individuals within stocks of Hainan, Fujian and Guangdong respectively, and 2.71% between Hainan and Fujian stocks, 2. 70% between Hainan and Guangdong stocks, 1.33% between Fujian and Guangdong stocks. Nucleofide diversity of sequences demonstrated that Hainan stock has a distant genetic relationship with Fujian stock and Guangdong stock, and the Fujian stock has a close relationship with Guangdong stock. In molecular phylogenetic tree constructed by UPGMA method, all the haplotypes of Hainan samples assembled one branch, while the haplotypes of Fujian and Guangdong samples intermixed together and assembled another branch. These results indicated that Hainan samples belong to a separate population, whereas the Fujian and Guangdong samples belong to an identical population. According to these data, we can deduce that gene exchange may exist widely between the stocks of Guangdong and Fujian. Base compositions of the mtDNA D-loop sequence were estimated by statistics programme of sofeware MEGA2.1. Significant differences of base comPositions were not observed among the samples of the three populations. The averages of the base A, T, C and G content were 34.1%, 31. 4 %, 20.3 % and 14.2 %, respectively. Therefore the total content of base A T was obviously higher than that of base G C. There was only one Site that base had been inserted or was absent. The amount of transition sites was more than that of transversion sites, which resemble other vertebrate.