Abstract：
Developmental evolution and diversification of morphology can arise through changes in the regulation of gene expression or protein-coding sequence. To unravel mechanisms underlying early developmental evolution in cavefish of the species Astyanax mexicanus, we compared transcriptomes of surface-dwelling and blind cave-adapted morphs at the end of gastrulation. Twenty percent of the transcriptome was differentially expressed. Allelic expression ratios in cave X surface hybrids showed that cis-regulatory changes are the quasi-exclusive contributors to inter-morph variations in gene expression. Among a list of 108 genes with change at the cis-regulatory level, we explored the control of expression of rx3, which is a master eye gene. We discovered that cellular rx3 levels are cis-regulated in a cell-autonomous manner, whereas rx3 domain size depends on non-autonomous Wnt and Bmp signalling. These results highlight how uncoupled mechanisms and regulatory modules control developmental gene expression and shape morphological changes. Finally, a transcriptome-wide search for fixed coding mutations and differential exon use suggested that variations in coding sequence have a minor contribution. Thus, during early embryogenesis, changes in gene expression regulation are the main drivers of cavefish developmental evolution.
摘要：
通过改变基因表达或蛋白质编码序列的调节，可以产生发育进化和形态多样化。为了阐明墨西哥Astyanax物种洞穴鱼早期发育进化的潜在机制，我们比较了原肠胚形成结束时表面居住和盲洞适应形态的转录组。20%的转录组差异表达。洞穴X表面杂种中的等位基因表达率表明，顺式调节变化是基因表达中形态间变异的准排他性因素。在108个顺式调控水平变化的基因中，我们探索了主眼基因rx3的表达控制。我们发现细胞rx3水平以细胞自主方式顺式调节，而rx3域大小取决于非自主Wnt和Bmp信号。这些结果突出了解耦机制和调节模块如何控制发育基因表达和形状形态变化。最后,对固定编码突变和差异外显子使用的全转录组搜索表明，编码序列的变异贡献较小。因此，在早期胚胎发生期间，基因表达调控的变化是洞穴鱼发育进化的主要驱动因素。
