广西钦洲湾养殖牡蛎线粒体16S rRNA基因片段序列变异分析

采用PCR技术对广西钦洲湾水域的养殖牡蛎(传统上被认为是近江牡蛎Crassotea ariakensis Fujita)群体26个个体的线粒体DNA16SrRNA基因片段序列进行扩增，获得了大约500bp的扩增产物。PCR产物经纯化后进行序列测定，经同源排序，得到415bp可供分析的核苷酸片段。26个个体中共检测到18个变异位点，包括1个碱基插入／缺失、11个转换位点及6个颠换位点。共有6种单倍型，这6种单倍型又分为2大类单倍型。运用MEGA软件计算出不同个体间的遗传距离，并构建了UPGMA和NJ系统树。26个个体聚成明显的2支，一支有19个个体，占73．08％；另一支有7个个体，占26．92％；2支间序列差异为3．54％。据此得出结论：钦洲湾养殖牡蛎应存在两大种群或是2个亚种，其差异是否到了种间的分界限，还需进一步研究证实。

Genetic diversity of Crassostrea from Qinzhou Bay in Guangxi using mtDNA 16S rRNA gene fragment sequence analysis

PCR technique was used to amplify the mtDNA 16S rRNA gene fragment in 26 individuals of southern oyster (called Crassotrea Ariakensis Fujita in tradition ) from Qinzhou Bay in Guangxi Province,and 500bp PCR products were gained approximately.The PCR products were purified and sequenced.As a result,415 bp nucleotide sequences of partial 16S rRNA gene that could be analysed were obtained (the primer and some of the marginal sequences were excluded).By using Clustal X to align and compare the sequences of the 26 individuals with each other,18 variation sites were observed,of which there were one insertion site,11 transition sites and 6 transversion sites.The pairwise genetic distances were computed by MEGA and the UPGMA and NJ phylogenetic trees were obtained through the cluster analysis over the pairwise genetic distance.The phylogenetic trees showed that the 26 individuals were performed clearly to 2 clades,where one clade has 19 individuals occupying 73.08%,and the other has 7 individuals occupying 26.92%,and the sequences differentiation of the two clades were 3.54%.It was induced that there were really two subspeices in the Qinzhou Bay.Further study should be conducted to get more evidences to verify that they belong to two species or two subspecies.