Department of Population Genetics, National Institute of Genetics, Misima 411-8540, Japan.
Proc Natl Acad Sci U S A. 2011 Sep 13;108(37):15276-81. doi: 10.1073/pnas.1105814108. Epub 2011 Aug 29.
Because distant species often share similar macromolecules, regulatory mutations are often considered responsible for much of their biological differences. Recently, a large portion of regulatory changes has been attributed to cis-regulatory mutations. Here, we examined an alternative possibility that the putative contribution of cis-regulatory changes was, in fact, caused by compensatory action of cis- and trans-regulatory elements. First, we show by stochastic simulations that compensatory cis-trans evolution maintains the binding affinity of a transcription factor at a constant level, thereby spuriously exaggerating the contribution of cis-regulatory mutations to gene expression divergence. This exaggeration was not observed when changes in the binding affinity were compensated by variable transcription factor concentration. Second, using reciprocal introgressions of Drosophila, we show that relative expression of heterozygous alleles from two distinct species often varied significantly between different species backgrounds, indicating the possible action of cis-trans compensation. Taken together, we propose that cis-trans hybrid incompatibilities are accumulating much faster than generally considered.
由于远距离物种通常具有相似的大分子，因此调节突变通常被认为是它们许多生物学差异的原因。最近，很大一部分调节变化归因于顺式调节突变。在这里，我们研究了另一种可能性，即假定顺式调节变化的贡献实际上是由顺式和反式调节元件的补偿作用引起的。首先，我们通过随机模拟表明，补偿性顺-反进化将转录因子的结合亲和力保持在恒定水平，从而错误地夸大了顺式调节突变对基因表达分化的贡献。当结合亲和力的变化由可变转录因子浓度补偿时，没有观察到这种夸大。其次，我们使用果蝇的相互渐渗，表明来自两个不同物种的杂合等位基因的相对表达在不同物种背景之间经常差异很大，这表明可能存在顺-反补偿作用。综上所述，我们提出顺-反杂种不亲和性的积累速度比通常认为的要快得多。
