暗纹东方鲀线粒体COIII克隆及序列分析

克隆并测定了暗纹东方鲀线粒体基因组(m tDNA)含完整的细胞色素氧化酶亚基Ⅲ(CO III)及其下游70 bp的tRNAG ly序列。CO III基因编码框包含786个核苷酸,编码262个氨基酸的蛋白质。鱼类CO III的序列组成对A T核苷酸的偏倚程度比较低。通过暗纹东方鲀与GenBank中8个目12种鱼类的CO III序列同源性比较,显示暗纹东方鲀与这些鱼类的CO III基因具有较高的同源性。根据暗纹东方鲀与鲀目其他5种鱼的CO III基因序列所建立的进化树,与传统的分类地位相吻合。推定的tR-NA的二级结构具有典型的三叶草型结构。根据CO III序列构建的分子进化树分析,认为在采用线粒体基因序列进行分子进化分析时,应综合考虑物种遗传变异的特点。

Cloning and Phylogenetic Analysis of Cytochrom Oxidase Subunit Ⅲ Gene of Mitochondrial Genome from Obscure Puffer (Takifugu obscurus)

The mitochondrial Cytochrome Oxidase III gene(COIII) in obscure puffer(Takifugu obscurus) and its adjacent tRNA-Gly gene were sequenced.The open reading frame of COIII gene contains 786 bp nucleotides,encoding a putative protein 262 amino acids.The pattern of codon usage of the COIII gene is less biased of A T.The COIII gene of obscure puffer was proved to have good homology with other 12 species of fish recorded in the GenBank and it has 97.9% homology with obscure puffer.The phylogenetic trees showed that the relationships based on the homology is consistent with the morphological taxonomic results.And it was proposed that the reproduction patterns and ecological characteristics should be considered when the molecular evolution is analysed based on mitochondrial genetic sequences.Assumed secondary structures of tRNA~(Gly) gene suggest that it has the classical cloverleaf structure.