Molecular evolution in nonrecombining regions of the Drosophila melanogaster genome.
Molecular evolution in nonrecombining regions of the Drosophila melanogaster genome.
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DOI：
10.1093/gbe/evs010
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发表时间：
2012
影响因子：
3.3
通讯作者：
Haddrill PR
中科院分区：
文献类型：
--
作者：
Campos JL;Charlesworth B;Haddrill PR
我们研究了减少重组对果蝇基因组的进化影响，分析了200多个缺乏交叉的新基因，并在黑腹果蝇亚群的物种中采用了一种新的同源搜索。这些基因位于点（第四）染色体以外的染色体的异染色质中。基因组的非交叉区域都表现出与D.在非同义位点的yakuba，较低的密码子使用偏好，较低的GC含量在编码区和非编码区，和较长的内含子。在有和没有交换的区域中，基因表达水平是相似的，这排除了我们检测到的适应水平降低是由于异染色质中基因表达水平较低而导致的放松选择造成的可能性。观察到的模式与D.黑腹果蝇缺乏交换，这是由于增强的Hill-Robertson干扰的影响。然而，我们也发现了nonrecombining位置之间的差异：X染色体似乎表现出最弱的影响，而第四染色体和位于最接近着丝粒的常染色体上的异染色质基因表现出最大的影响。然而，在所有异染色质区域中，非同义突变和密码子使用的选择签名都持续存在。
We study the evolutionary effects of reduced recombination on the Drosophila melanogaster genome, analyzing more than 200 new genes that lack crossing-over and employing a novel orthology search among species of the melanogaster subgroup. These genes are located in the heterochromatin of chromosomes other than the dot (fourth) chromosome. Noncrossover regions of the genome all exhibited an elevated level of evolutionary divergence from D. yakuba at nonsynonymous sites, lower codon usage bias, lower GC content in coding and noncoding regions, and longer introns. Levels of gene expression are similar for genes in regions with and without crossing-over, which rules out the possibility that the reduced level of adaptation that we detect is caused by relaxed selection due to lower levels of gene expression in the heterochromatin. The patterns observed are consistent with a reduction in the efficacy of selection in all regions of the genome of D. melanogaster that lack crossing-over, as a result of the effects of enhanced Hill–Robertson interference. However, we also detected differences among nonrecombining locations: The X chromosome seems to exhibit the weakest effects, whereas the fourth chromosome and the heterochromatic genes on the autosomes located most proximal to the centromere showed the largest effects. However, signatures of selection on both nonsynonymous mutations and on codon usage persist in all heterochromatic regions.
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影响因子：
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