东山湾青石斑鱼线粒体DNA D-loop区遗传多样性分析

Analysis of mitochondrial DNA D-loop genetic diversity of Epinephelus awoara in Dongshan Bay

为研究青石斑鱼种群遗传结构以实现资源保护和可持续利用,实验采用PCR技术对东山湾水域53尾青石斑鱼种群的线粒体DNA（mtDNA）D-loop区全序列进行扩增并测序,序列长度为956～1 230 bp,变异很大,这可能是由于5＇端含有数目不等的重复序列单元（repeat sequence unit,RSU）或者由于碱基的插入和缺失造成的。按照RSU数目的不同,把53个青石斑鱼样本分为3大类：2RSU类（占11.3%）、3RSU类（占77.4%）、4RSU类（占11.3%）。采用MEGA（version 3.0）和DnaSP（version 4.0）软件对序列进行分析,结果显示,53条序列的T、C、A和G碱基平均含量分别为33.4%、17.3%、35.4%和13.9%,共发现53种单倍型,包括179个多态位点,单倍型间平均遗传距离为0.019 7,单倍型多态性（Hd）为1.000,核苷酸多态性（π）值为0.017 2。研究表明,东山湾青石斑鱼种群的遗传多样性处于中等水平。

This experiment was to study the genetic structure of E. awoara,which could realize effective resource conservation and sustainable use of this species. PCR was used to amplify the complete sequences of the mitochondrial DNA（ mtDNA） D-loop region of 53 individuals of E. awoara collected from Dongshan Bay. Because 5＇ end contained different numbers of repeat sequence units（ RSU） and D-loop region had base insertion or deletion,sequences length of 53 E. awoara individuals ranged from 956 bp to 1 230 bp. 53 E.awoara individuals were divided into three groups： 2RSU（ 11. 3%）,3RSU（ 77. 4%）,4RSU（ 11. 3%）.Sequences were analyzed with the MEGA（ version 3. 0） and DnaSP（ version 4. 0） softwares. The results showed as follows： The average content of T,C,A and G was 33. 4%,17. 3%,35. 4% and 13. 9%,respectively. 179 polymorphic sites were detected yielding 53 haplotypes. The average genetic distance of haplotypes is 0. 019 7. The haplotype diversity was 1. 000（ Hd）. The nucleotide diversity was 0.017 2（ π）. It is concluded that the genetic diversity of the E. awoara population in Dongshan Bay was at a medium level in mitochondrial DNA control region sequences.