Brown W M, George M, Wilson A C
Proc Natl Acad Sci U S A. 1979 Apr;76(4):1967-71. doi: 10.1073/pnas.76.4.1967.
Mitochondrial DNA was purified from four species of higher primates (Guinea baboon, rhesus macaque, guenon, and human) and digested with 11 restriction endonucleases. A cleavage map was constructed for the mitochondrial DNA of each species. Comparison of the maps, aligned with respect to the origin and direction of DNA replication, revealed that the species differ from one another at most of the cleavage sites. The degree of divergence in nucleotide sequence at these sites was calculated from the fraction of cleavage sites shared by each pair of species. By plotting the degree of divergence in mitochondrial DNA against time of divergence, the rate of base substitution could be calculated from the initial slope of the curve. The value obtained, 0.02 substitutions per base pair per million years, was compared with the value for single-copy nuclear DNA. The rate of evolution of the mitochondrial genome appears to exceed that of the single-copy fraction of the nuclear genome by a factor of about 10. This high rate may be due, in part, to an elevated rate of mutation in mitochondrial DNA. Because of the high rate of evolution, mitochondrial DNA is likely to be an extremely useful molecule to employ for high-resolution analysis of the evolutionary process.
从四种高等灵长类动物（几内亚狒狒、恒河猴、长尾猴和人类）中纯化出线粒体DNA，并用11种限制性内切酶进行消化。构建了每个物种线粒体DNA的切割图谱。将这些图谱相对于DNA复制的起点和方向进行比对，结果显示在大多数切割位点上，这些物种彼此不同。根据每对物种共有的切割位点比例，计算出这些位点核苷酸序列的分歧程度。通过绘制线粒体DNA的分歧程度与分歧时间的关系图，可从曲线的初始斜率计算出碱基替换率。得到的值为每百万年每碱基对0.02次替换，并将其与单拷贝核DNA的值进行比较。线粒体基因组的进化速率似乎比核基因组单拷贝部分的进化速率高出约10倍。这种高进化速率可能部分归因于线粒体DNA较高的突变率。由于进化速率高，线粒体DNA可能是用于进化过程高分辨率分析的极其有用的分子。
