五种啮齿类动物mtDNA蛋白编码基因序列变化的比较

目的利用本实验室测定的中国地鼠、金黄地鼠和GenBank中田鼠、小鼠、大鼠的线粒体全基因组序列,比较分析五种啮齿类动物的mtDNA蛋白编码基因序列的变异,探讨其分子进化关系。方法将五种动物各自的13个蛋白编码基因分别连接成一个序列,用DNAstar-EditSeq分析软件计算每个序列的碱基长度和组成,计算蛋白编码基因的碱基和氨基酸的差异。以人为外群,基于连接在一起的13个蛋白编码基因的氨基酸序列,用MEGA4.0软件通过最大简约性法(MP)和非加权成对平均数法(UPGMA)构建进化树。结果在五种啮齿动物的13个蛋白基因序列中,A、T、C、G碱基的平均含量为32.4%、29.6%、26.2%和11.9%,中国地鼠mtDNA各蛋白编码序列以及其编码的氨基酸序列与其他物种相比,与金黄地鼠的相应序列差异最小,与大鼠mtDNA各蛋白编码序列以及其编码的氨基酸序列差异较大。分子进化树也显示中国地鼠和金黄地鼠的亲缘关系最近,与小鼠、大鼠存在的差异相对大。结论五种动物的碱基组成的百分比中显示G的相对缺乏,相互之间的进化关系与传统的分类地位基本吻合。

Comparison of mitochondrial protein-coding gene sequences in five murine species

Objective Using the complete mitochondrial genome sequences of Chinese hamster （ Cricetulus gri- seus） and golden hamsters （Mesocricetus auratus） determined in our laboratory and those of mice （Mus musculus） , rat （Rattus norvegicus） and voles （Mierotus kikuehi） downloaded from the GenBank, protein-coding genes of mtDNA were an- alyzed, and to explore their moleeular evolutional relationship. Methods The base composition, codon usage, and nucle- otide substitution were analyzed with DNAstar software. Genetie distances and percent similarities of bases of the protein coding genes were analyzed with software Mega 4. 0. Taking human as the out-group, molecular phylogenetic trees were constructed based on concatenated sequences of whole protein-coding genes of the mitochondrial genomes with maximum parsimony ~MP） , unweighted pair-group method with arithmetie means （UPGMA） methods. Results Comparative analy- sis among the five murine species showed that the genome size, gene content, codon usage, and base composition were considerably variable. The A, T, C, G base average contents were 32.4 % , 29.6% , 26. 2% and 11.9 % , respectively. The protein-coding sequence and amino acid sequence of Cricetulus griseus showed the least difference with that of Mesocricetus auratus, and the largest difference with that of Rattus norvegicus. The topological structures of the two trees were consistent, and they all showed that the relationship between the Cricetulus griseus and Mesocricetus auratus was much closer than that between Mus musculus, Rattus norvegicus and Microtus kikuchi. Conclusions There are relative lack of guanine in the base composition percentage in the five species of animals. The evolutionary relationships of each other are consistent with the traditional classification status.