Nonrecombining genes in a recombination environment: the Drosophila "dot" chromosome.
Nonrecombining genes in a recombination environment: the Drosophila "dot" chromosome.
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重组环境中的非重组基因：果蝇“点”染色体。
DOI：
10.1093/molbev/msq258
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发表时间：
2011
影响因子：
10.7
通讯作者：
Garrick,RyanC
中科院分区：
文献类型：
--
作者：
Powell,JeffreyR;Dion,Kirstin;Papaceit,Montserrat;Aguadé,Montserrat;Vicario,Saverio;Garrick,RyanC
重组速率是影响分子变异和进化的几个方面的强大变量。大多数果蝇物种基因组的一个非重组部分，即“点”染色体，表现出非常低的变异水平和不寻常的密码子使用。果蝇的一个谱系，Wilistoni/Saltansgroup，将F元素与正常重组的E元素融合在一起。在这里，我们提供了两个果蝇和OneD的F元素基因的多态数据。Inisaris种群，以前研究的基因是Ind.黑猩猩。太棒了。已知威利斯通种群的倒位多态很低，因此将倒位的重组抑制作用降至最低。我们首先用原位杂交的方法证实了这一点。胰岛素样病变为SAME+FFusion ASD。Wilistoni，暗示这是一个单系学事件。密码子的使用沿着WillistoniF元件存在着明显的梯度，从着丝粒的远端到与着丝粒的融合；重组率的估计与此梯度平行，也表明。胰岛素具有较大的复合能力。威利斯托尼。相比之下，TOD。黑素基因表现出中等水平的核苷酸多态，与基因组中其他两个基因没有区别。虽然在基因内的多态位点之间检测到了一定的连锁不平衡(LD)(一般相隔500个碱基)，但在这两个群种中不存在FElement座位之间的长距离连锁不平衡(LD)。总体而言，F元素基因的等位基因频率分布呈现典型的平衡中性变异预期模式。这些结果与重组允许核苷酸变异积累以及允许选择作用于同义密码子使用的假设是一致的。据估计，融合发生在∼20Mya，虽然威利斯顿谱系中的F元素已经进化出“正常”的核苷酸变异水平和模式，但密码子的使用可能还没有达到平衡。
Rate of recombination is a powerful variable affecting several aspects of molecular variation and evolution. A nonrecombining portion of the genome of most Drosophila species, the “dot” chromosome orFelement, exhibits very low levels of variation and unusual codon usage. One lineage of Drosophila, thewillistoni/saltansgroups, has theFelement fused to a normally recombiningEelement. Here, we present polymorphism data for genes on theFelement in twoDrosophila willistoniand oneD. insularispopulations, genes previously studied inD. melanogaster. TheD. willistonipopulations were known to be very low in inversion polymorphism, thus minimizing the recombination suppression effect of inversions. We first confirmed, by in situ hybridization, thatD. insularishas the sameE+Ffusion asD. willistoni, implying this was a monophyletic event. A clear gradient in codon usage exists along thewillistoniFelement, from the centromere distally to the fusion withE; estimates of recombination rates parallel this gradient and also indicateD. insularishas greater recombination thanD. willistoni. In contrast toD. melanogaster, genes on theFelement exhibit moderate levels of nucleotide polymorphism not distinguishable from two genes elsewhere in the genome. Although some linkage disequilibrium (LD) was detected between polymorphic sites within genes (generally <500 bp apart), no long-range LD betweenFelement loci exists in the twowillistonigroup species. In general, the distribution of allele frequencies ofFelement genes display the typical pattern of expectations of neutral variation at equilibrium. These results are consistent with the hypothesis that recombination allows the accumulation of nucleotide variation as well as allows selection to act on synonymous codon usage. It is estimated that the fusion occurred ∼20 Mya and while theFelement in thewillistonilineage has evolved “normal” levels and patterns of nucleotide variation, equilibrium may not have been reached for codon usage.