Synergistic epistasis of the deleterious effects of transposable elements.
Synergistic epistasis of the deleterious effects of transposable elements.
复制标题
转座因子有害作用的协同上位性。
DOI：
10.1093/genetics/iyab211
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发表时间：
2022
期刊：
影响因子：
3.3
通讯作者：
Lee,YuhChwenG
中科院分区：
文献类型：
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作者：
Lee,YuhChwenG
转座因子（TE）的复制性质和一般有害作用提出了一个悬而未决的问题，即TE拷贝数如何在宿主群体中稳定地包含。经典理论分析预测，当每次额外的TE插入导致的适应度下降大于线性，或者存在协同上位时，针对TE的选择可以导致TE拷贝数的稳定平衡。虽然有几种机制被预测会产生TEs的协同有害效应，但我们缺乏对这种上位相互作用存在的实证研究。协同上位的净化选择在有害等位基因之间产生排斥连锁。我们在可能的黑腹果蝇祖先群体中研究了这一群体遗传信号，并发现了支持TE插入之间存在协同上位的证据，特别是那些预计会对适应度产生重大影响的TE。尽管已经预测te的协同上位是通过异位重组和te介导的表观遗传沉默机制产生的，但我们只发现了对相关预测的混合支持。我们在大量TE家族中观察到协同上位的信号，这与预期一致，即这种上位相互作用主要发生在同一家族的拷贝之间。奇怪的是，在不同家族的TE插入之间也发现了显著的排斥连锁，这表明TE有害适应度效应的协同作用可能出现在家族水平之上，并且通过类似于简单突变的机制。我们的研究结果为研究TEs进化动力学中上位相互作用的普遍性和重要性奠定了基础。
The replicative nature and generally deleterious effects of transposable elements (TEs) raise an outstanding question about how TE copy number is stably contained in host populations. Classic theoretical analyses predict that, when the decline in fitness due to each additional TE insertion is greater than linear, or when there is synergistic epistasis, selection against TEs can result in a stable equilibrium of TE copy number. While several mechanisms are predicted to yield synergistic deleterious effects of TEs, we lack empirical investigations of the presence of such epistatic interactions. Purifying selection with synergistic epistasis generates repulsion linkage between deleterious alleles. We investigated this population genetic signal in the likely ancestralDrosophila melanogasterpopulation and found evidence supporting the presence of synergistic epistasis among TE insertions, especially TEs expected to exert large fitness impacts. Even though synergistic epistasis of TEs has been predicted to arise through ectopic recombination and TE-mediated epigenetic silencing mechanisms, we only found mixed support for the associated predictions. We observed signals of synergistic epistasis for a large number of TE families, which is consistent with the expectation that such epistatic interaction mainly happens among copies of the same family. Curiously, significant repulsion linkage was also found among TE insertions from different families, suggesting the possibility that synergism of TEs’ deleterious fitness effects could arise above the family level and through mechanisms similar to those of simple mutations. Our findings set the stage for investigating the prevalence and importance of epistatic interactions in the evolutionary dynamics of TEs.