Singh Nadia D, Davis Jerel C, Petrov Dmitri A
Department of Biological Sciences, Stanford University, 371 Serra Mall, Stanford, California, 90305-5020, USA.
J Mol Evol. 2005 Sep;61(3):315-24. doi: 10.1007/s00239-004-0287-1. Epub 2005 Jul 21.
The patterns and processes of molecular evolution may differ between the X chromosome and the autosomes in Drosophila melanogaster. This may in part be due to differences in the effective population size between the two chromosome sets and in part to the hemizygosity of the X chromosome in Drosophila males. These and other factors may lead to differences both in the gene complements of the X and the autosomes and in the properties of the genes residing on those chromosomes. Here we show that codon bias and recombination rate are correlated strongly and negatively on the X chromosome, and that this correlation cannot be explained by indirect relationships with other known determinants of codon bias. This is in dramatic contrast to the weak positive correlation found on the autosomes. We explored possible explanations for these patterns, which required a comprehensive analysis of the relationships among multiple genetic properties such as protein length and expression level. This analysis highlights conserved features of coding sequence evolution on the X and the autosomes and illuminates interesting differences between these two chromosome sets.
在黑腹果蝇中，X染色体和常染色体的分子进化模式与过程可能存在差异。这部分可能是由于两组染色体的有效种群大小不同，部分是由于果蝇雄性中X染色体的半合子状态。这些因素以及其他因素可能导致X染色体和常染色体的基因组成以及位于这些染色体上的基因特性都存在差异。我们在此表明，X染色体上密码子偏好与重组率呈强烈的负相关，且这种相关性无法通过与其他已知密码子偏好决定因素的间接关系来解释。这与在常染色体上发现的微弱正相关形成了鲜明对比。我们探究了这些模式的可能解释，这需要对蛋白质长度和表达水平等多种遗传特性之间的关系进行全面分析。该分析突出了X染色体和常染色体上编码序列进化的保守特征，并揭示了这两组染色体之间有趣的差异。
