大鳞副泥鳅mtDNA Cytb基因序列分析及分子系统发育研究

Analysis of Mitochondrial DNA Cytochrome b Gene Sequence and Molecular Phylogeny in Paramisgurnus dabryanus Sauvage

对15尾大鳞副泥鳅的线粒体细胞色素b基因进行PCR扩增和正反测序,获得长度为1140 bp的细胞色素b基因同源片断。所有序列中共检测到15种单倍型,序列中共出现81个变异位点,总变异率为7.1%。各单倍型的变异全部是转换或颠换,无插入和缺失,转换/颠换比为6.36。变异位点在3位密码子中的分布呈现偏倚,密码子第3位的变异占总变异的85.18%,而第1和第2位均只占7.41%。A、T、C、G碱基的平均含量分别为27.4%、30.8%、26.5%、15.3%,A+T>C+G。在所得序列中,密码子第1位上4种碱基使用较为均衡;第2位上碱基T的使用率高达41%,碱基G的使用率低至13.2%;第3位上碱基A的使用率为37.9%,而碱基G的使用率仅为7.0%。以红尾副鳅为外群用邻接法构建分子系统进化树。结果显示,在系统地位上大鳞副泥鳅与黑龙江泥鳅有较近的亲缘关系。

Mitochondrila DNA cytochrome b gene was amplified by PCR and sequenced in two directions in 15 fish samples of Paramisgurnus dabryanus Sauvage,and 1140 bp homologous sequences of the cytochrome b gene were obtained.A total of 15 haplotypes and 81 variable sites were detected in all these sequences,with total variation rate of 7.1%.There was no insertion or deletion among the variations which were all transitional and transversional with the transition rate of 6.36 in the 15 haplotypes.The variable sites were biased in the codons,with the variation of 85.18% in the third position,and 7.41% in the first and second positions.The average contents were found 27.4% for A,30.8% for T,26.5% for C,and 15.3% for G,A＋TC＋G.The first position of codons had even usage in 4 nucleotides;the second position of the codons in the gene had a high content of T（41%）,but low content of G（13.2%）;and the third had 37.9% of A and 7.0% of G.The molecular phylogenetic tree of mtDNA Cytb of the fishes in Cobitinae and the Paracobitis variegatus individuals was constructed by Neighbor-Joining method,indicating that P.dabryanus Sauvage had a closer genetic relationship with Misgurnus mohoity.