三斑海马线粒体基因组核苷酸全序列结构与分析

通过PCR扩增并测序获得了三斑海马(Hippocampus trimaculatus)线粒体DNA(mt DNA)全序列。三斑海马线粒体基因组全序列长度为16 534 bp(Gen Bank登录号为KJ956892),编码37个基因,包括13个蛋白编码基因、22个t RNA基因和2个r RNA基因。非编码区域包括1个控制区(D-loop)及一个轻链复制起始区域。大部分基因由H-链编码,包括14个t RNA基因、2个r RNA基因、12个蛋白编码基因;只有ND6和8个t RNA基因是在L-链编码。预测的22个t RNA基因的二级结构均为典型的三叶草状。基因间隔一般1~14 bp不等。此外,还存在7处碱基重叠,其中,4处是鱼类和脊椎动物典型的基因重叠位点。总的碱基含量分别为,A 32.7%,C 23.4%,G 14.6%,T 29.3%,A+T含量为62.0%。其线粒体基因组序列的结构与脊椎动物的典型结构近似。邻接法和贝叶斯法构建的三斑海马系统进化树的拓扑结构相似,这与现有的三斑海马的系统演化地位一致。本研究为海马的进化研究以及保护工作提供了基础数据。

Structure and Analysis of Complete Mitochondial Genome of Hippocampus trimaculatus

The nucleotide sequence of the complete mitochondrial DNA (mtDNA) genome was determined in Hippocampus trimaculatus. The complete mitogenome of H. trimaculatus was 16,529 bp with the GenBank Accession No. KJ956892, and it consisted of 13 protein-coding genes, 22 tRNA genes, 12S rRNA gene, 16S rRNA gene and 1 control region (D-loop). The heavy DNA strand (H-strand) carried most of the genes: 12 protein-coding genes, 2 rRNA and 14 tRNA. ND6 and eight tRNA genes were encoded on the L-strand. The lengths of 22 tRNA genes ranged from 66 to 76 bp, and all of them could fold into the typical cloverleaf-shaped secondary structure. The lengths of intergenic nucleotide are range from 1 to 14 bp with 7 overlaps inside. While four of the seven overlaps??ATP8 and ATP6, ATP6 and COIII, ND4L and ND4, ND5 and ND6?? are typical overlap sites of the teleost. The overall base composition of H. trimaculatus is 32.7% A, 29.3% T, 14.6% G and 23.4% C, with a slight A + T rich feature (62.0%). The gene order and composition of H. trimaculatus were similar to those of most other vertebrates. Two phylogenetic trees constructed by Neigbour-joining and Bayesian methods showed basically the same result. Seven species of genus Hippocampus clustered into a branch, which supported the existing classification of these seahorses.