GC-biased segregation of noncoding polymorphisms in Drosophila
GC-biased segregation of noncoding polymorphisms in Drosophila
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DOI：
10.1534/genetics.105.046524
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发表时间：
2006-01-01
期刊：
影响因子：
3.3
通讯作者：
Bierne, N
中科院分区：
文献类型：
--
作者：
Galtier, N;Bazin, E;Bierne, N
果蝇碱基组成进化的研究大多是通过对编码序列的分析来实现的。然而，第三个密码子位置GC含量受到中性力（如突变偏倚）和自然选择对密码子使用优化的影响。本文从公共数据库中收集了黑腹龙葵和拟马虎非编码DNA序列多态性的大量数据集，试图解开这两个因素——非编码序列不受密码子使用选择的影响。等位基因频率分析揭示了AT与GC非编码多态性的不对称模式：AT ->突变比GC- >突变数量少，且倾向于以更高的频率分离，特别是在富含GC的位点上。这表明碱基组成的非平稳进化和/或gc偏向等位基因的传播。将群体遗传学模型与等位基因频谱拟合证实了这一结果，并支持偏传的假设。这些结果与之前的报道一起表明，GC偏向的基因转换影响了果蝇的碱基组成进化，并解释了内含子和外显子GC含量之间的相关性。
The study of base composition evolution in Drosophila has been achieved mostly through the analysis of coding sequences. Third codon position GC content, however, is influenced by both neutral forces (e.g., mutation bias) and natural selection for codon usage optimization. In this article, large data sets of noncoding DNA sequence polymorphism in D. melanogaster and D. simulans were gathered front public databases to try to disentangle these two factors-noncoding sequences are not affected by selection for codon usage. Allele frequency analyses revealed an asymmetric pattern of AT vs. GC noncoding polymorphisms: AT -> GC mutations are less numerous, and tend to segregate at a higher frequency, than GC -> AT ones, especially at GC-rich loci. This is indicative of nonstationary evolution of base composition and/or of GC-biased allele transmission. Fitting population genetics models to the allele frequency spectra confirmed this result and favored the hypothesis of a biased transmission. These results, together with previous reports, suggest that GC-biased gene conversion has influenced base composition evolution in Drosophila and explain the correlation between intron and exon GC content.