Tsunoyama K, Bellgard M I, Gojobori T
Department of Genetics, Graduate University for Advanced Studies, Mishima, Japan.
J Mol Evol. 2001 Oct-Nov;53(4-5):456-64. doi: 10.1007/s002390010235.
It has been observed that synonymous substitution rates vary among genes in various organisms, although the cause of the variation is unresolved. At the intragenic level, however, the variation of synonymous substitutions is somewhat controversial. By developing a rigorous statistical test and applying the test to 418 homologous gene pairs between mouse and rat, we found that more than 90% of gene pairs showed a statistical significance in intragenic variation of synonymous substitution rates. Moreover, by examining all conceivable possibilities for the cause of the variation, we successfully found that intragenic variation of synonymous substitutions in mammalian genes is caused mainly by a nonrandom mutation due to the methylation of CpG dinucleotides rather than by functional constraints.
据观察，同义替换率在各种生物体的基因中有所不同，尽管这种变异的原因尚未得到解决。然而，在基因内部水平上，同义替换的变异存在一定争议。通过开发一种严格的统计测试并将其应用于小鼠和大鼠之间的418对同源基因对，我们发现超过90%的基因对在同义替换率的基因内变异方面具有统计学意义。此外，通过研究变异原因的所有可能情况，我们成功发现哺乳动物基因中同义替换的基因内变异主要是由CpG二核苷酸甲基化导致的非随机突变引起的，而非功能限制。
