喀斯特山区大眼鳜线粒体COⅠ基因序列分析

为了解喀斯特山区大眼鳜3个地理群体内和群体间的遗传变异特点,采用PCR技术对169尾个体的线粒体DNA COⅠ基因进行扩增、测序,获得的序列长度为1512bp。分析显示,碱基A、T、C、G的平均含量分别为24.9%、28.6%、28.7%、17.8%,其中A+T(53.5%)含量高于G+C(46.5%)含量。169个样本共检测到5个多态位点,并定义了5种单倍型。对喀斯特山区大眼鳜群体COⅠ基因与洞庭湖大眼鳜COⅠ基因序列进行序列差异分析,结果显示,两者之间存在10个变异位点,集中在1268~1456nt。喀斯特山区3个群体间4种碱基在密码子3个位点上的使用频率无差别,与洞庭湖大眼鳜相比,密码子第1位上的4种碱基含量差别不大,密码子第2位上T含量(40.9%)高于后者(39.9%),而A和C含量则低于后者;与洞庭湖翘嘴鳜比较差别很小,但与斑鳜、暗鳜、长身鳜和波纹鳜4种鳜鱼比较,在密码子第1位和第3位存在不同差异,特别是暗鳜和波纹鳜密码子第3位中A含量(30.0%)明显低于喀斯特山区大眼鳜(31.8%),而波纹鳜G(8.9%)明显高于后者(7.3%)。喀斯特山区大眼鳜平均单倍型多样性为0.395,平均核苷酸多样性为0.00029,遗传多样性贫乏。

Sequence Analysis of Cytochrome C Oxidase Subunit Ⅰ (COⅠ) of Mitochondrial DNA Gene of Bigeye Mandarinfish Siniperca kneri in Karst Mountain

The partial mitochondrial CO Ⅰ sequences of 169 individuals of bigeye mandarinfish Siniperca kneri from three populations in Karst Mountain were amplified by PCR technique to analyze their sequence variation and the 1512 bp nucleotide sequences were obtained .The amplification showed that the average contents of A ,T ,G and C were 24 .9% ,28 .6% ,28 .7% and 17 .8% ,respectively ,the average content of AT(53 .5% ) being higher than that of GC (46 .5% ) .Five variable sites were detected and five different haplotypes were defined in 169 samples of the populations ,and the 10 variable loci were detected between the populations of S .kneri in Karst Mountain and S .kneri in Dongting lake ,most of which were occurred from 1268 nt to 1456 nt .There were no difference about codon usage among the three populations in Karst Mountain .Comparing to S .kneri in Dongting lake ,there were no significant differences in the first posi‐tions of codon usage ,higher content of T (40 .9% ) than the latter (39 .9% ) in the second codon positions , whereas the content of A and C was lower than the latter in the third codon positions .The codon usage was small discriminatory between bigeye mandarinfish in Karst Mountain and mandarinfish S .chuatsi in Dongting lake .Comparison of S .scherzeri ,S .obscura ,S .roulei and S .undulata revealed different dis‐criminatory at the first codon positions and third codon positions ,especially significantly lower content of A(30 .0% ) in S .obscura and S .undulata at the codon first positions than that (31 .8% ) in S .akneri in Karst mountain ,whereas G content (8 .9% ) of S . undulata was significantly higher than the latter (7 .3% ) .The total haplotype diversity (Hd) was 0 .395 and nucleotide diversity(Pi) was 0 .00029 ,there‐fore ,indicating a low genetic diversity level in the populations of S .kneri in Karst Mountain .