Evidence of the adaptive evolution of immune genes in chicken.
Evidence of the adaptive evolution of immune genes in chicken.
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DOI：
10.1186/1756-0500-2-254
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发表时间：
2009-12-15
影响因子：
1.8
通讯作者：
Lloyd, Andrew T
中科院分区：
文献类型：
--
作者：
Downing, Tim;Cormican, Paul;Lloyd, Andrew T
斑马雀是第二种被广泛测序的鸟类，目前正在进行的斑马雀基因组测序已经增强了对鸡基因功能类别特征的理解基础。该序列为研究鸡从其与斑胸草雀的共同祖先分离以来的变异进化提供了鸟类背景，也为研究鸡的种内多样性提供了一个校准点。免疫基因在其进化史上经历了许多选择过程：本文在一组同源鸡和斑胸草雀基因中研究了这类基因，它们的功能来自人类同源基因。试验表明，免疫基因的非同义位点在鸡和禽类谱系中都高度保守。McDonald-Kreitman测试提供了适应性进化的证据，并且与非免疫基因相比，免疫基因上的非同义替换固定的选择率更高。进一步分析表明，鸡中GC含量远高于斑胸草雀基因，且两种免疫基因中GC含量均显著升高。病原体的挑战很可能驱动了鸡免疫基因变异的选择力，并继续限制这一功能类的多样性。
The basis for understanding the characteristics of gene functional categories in chicken has been enhanced by the ongoing sequencing of the zebra finch genome, the second bird species to be extensively sequenced. This sequence provides an avian context for examining how variation in chicken has evolved since its divergence from its common ancestor with zebra finch as well as well as a calibrating point for studying intraspecific diversity within chicken. Immune genes have been subject to many selective processes during their evolutionary history: this gene class was investigated here in a set of orthologous chicken and zebra finch genes with functions assigned from the human ortholog. Tests demonstrated that nonsynonymous sites at immune genes were highly conserved both in chicken and on the avian lineage. McDonald-Kreitman tests provided evidence of adaptive evolution and a higher rate of selection on fixation of nonsynonymous substitutions at immune genes compared to that at non-immune genes. Further analyses showed that GC content was much higher in chicken than in zebra finch genes, and was significantly elevated in both species' immune genes. Pathogen challenges are likely to have driven the selective forces that have shaped variation at chicken immune genes, and continue to restrict diversity in this functional class.