Pumo D E, Phillips C J, Barcia M, Millan C
Department of Biology, Hofstra University, Hempstead, NY 11550.
J Mol Evol. 1992 Feb;34(2):163-74. doi: 10.1007/BF00182393.
The DNA sequence was determined for the cytochrome c oxidase II (COII), tRNALys, and ATPase 8 genes from the mitochondrial genome of the meadow vole, Microtus pennsylvanicus. When compared to other rodents, three different patterns of evolutionary divergence were found. Nucleotide variation in tRNALys is concentrated in the T psi C loop. Nucleotide variation in the COII gene in three genera of rodents (Microtus, Mus, Rattus) consists predominantly of transitions in the third base positions of codons. The predicted amino acid sequence in highly conserved (greater than 92% similarity). Analysis of the ATPase 8 gene among four genera (Microtus, Cricetulus, Mus, Rattus) revealed more detectable transversions than transitions, many fixed first and second position mutations, and considerable amino acid divergence. The rate of nucleotide substitution at nonsynonymous sites in the ATPase 8 gene is 10 times the rate in the COII gene. In contrast, the estimated absolute mutation rate as determined by analysis of nucleotide substitutions at fourfold degenerate sites probably is the same for the two genes. The primary sequences of the ATPase 8 and COII peptides are constrained differently, but each peptide is conserved in terms of predicted secondary-level configuration.
测定了草原田鼠（Microtus pennsylvanicus）线粒体基因组中细胞色素c氧化酶II（COII）、赖氨酸转运RNA（tRNALys）和ATP酶8基因的DNA序列。与其他啮齿动物相比，发现了三种不同的进化分歧模式。tRNALys中的核苷酸变异集中在TψC环。三种啮齿动物属（田鼠属、小家鼠属、大鼠属）的COII基因中的核苷酸变异主要由密码子第三碱基位置的转换组成。预测的氨基酸序列高度保守（相似度大于92%）。对四个属（田鼠属、仓鼠属、小家鼠属、大鼠属）的ATP酶8基因分析显示，可检测到的颠换比转换更多，许多第一和第二位置的突变固定下来，并且氨基酸分歧较大。ATP酶8基因非同义位点的核苷酸替换率是COII基因的10倍。相比之下，通过对四倍简并位点的核苷酸替换分析确定的估计绝对突变率可能对这两个基因是相同的。ATP酶8和COII肽的一级序列受到不同的限制，但每个肽在预测的二级结构方面都是保守的。
