Schlenke Todd A, Begun David J
Section of Evolution and Ecology, Division of Biological Sciences, Storer Hall, University of California, Davis, CA 95616, USA.
Genetics. 2003 Aug;164(4):1471-80. doi: 10.1093/genetics/164.4.1471.
Evidence from disparate sources suggests that natural selection may often play a role in the evolution of host immune system proteins. However, there have been few attempts to make general population genetic inferences on the basis of analysis of several immune-system-related genes from a single species. Here we present DNA polymorphism and divergence data from 34 genes thought to function in the innate immune system of Drosophila simulans and compare these data to those from 28 nonimmunity genes sequenced from the same lines. Several statistics, including average K(A)/K(S) ratio, average silent heterozygosity, and average haplotype diversity, significantly differ between the immunity and nonimmunity genes, suggesting an important role for directional selection in immune system protein evolution. In contrast to data from mammalian immunoglobulins and other proteins, we find no strong evidence for the selective maintenance of protein diversity in Drosophila immune system proteins. This may be a consequence of Drosophila's generalized innate immune response.
来自不同来源的证据表明，自然选择可能经常在宿主免疫系统蛋白质的进化中发挥作用。然而，基于对单个物种的几个免疫系统相关基因的分析来进行一般群体遗传学推断的尝试很少。在这里，我们展示了来自34个被认为在拟果蝇先天免疫系统中起作用的基因的DNA多态性和分化数据，并将这些数据与从同一品系中测序的28个非免疫基因的数据进行比较。包括平均K(A)/K(S)比率、平均沉默杂合度和平均单倍型多样性在内的几个统计数据，在免疫基因和非免疫基因之间存在显著差异，这表明定向选择在免疫系统蛋白质进化中起重要作用。与来自哺乳动物免疫球蛋白和其他蛋白质的数据相反，我们没有发现果蝇免疫系统蛋白质中蛋白质多样性受到选择性维持的有力证据。这可能是果蝇普遍的先天免疫反应的结果。
