Sawyer S A, Dykhuizen D E, Hartl D L
Proc Natl Acad Sci U S A. 1987 Sep;84(17):6225-8. doi: 10.1073/pnas.84.17.6225.
A statistical approach to the analysis of DNA sequences has been developed, which provides a confidence interval estimate for the proportion of naturally occurring amino acid polymorphisms that are selectively neutral. When applied to the gnd gene coding for 6-phosphogluconate dehydrogenase in a sample of seven natural isolates of Escherichia coli, the method indicates that the proportion of observed amino acid polymorphisms that are selectively neutral is unlikely to be greater than 49% (upper 95% confidence limit). On the other hand, the observations are also consistent with a model in which all of the observed amino acid substitutions are mildly deleterious with an average selection coefficient approximating 1.6 X 10(-7). Various models for the distribution of configurations at silent sites are also investigated.
已开发出一种用于分析DNA序列的统计方法，该方法可为自然发生的选择性中性氨基酸多态性比例提供置信区间估计。当将此方法应用于编码6-磷酸葡萄糖酸脱氢酶的gnd基因，该基因取自大肠杆菌的七个自然分离株样本时，结果表明观察到的选择性中性氨基酸多态性比例不太可能大于49%（95%置信上限）。另一方面，这些观察结果也与一个模型相符，在该模型中，所有观察到的氨基酸替换均具有轻微的有害性，平均选择系数约为1.6×10⁻⁷。还研究了沉默位点构型分布的各种模型。
