Natural selection on cis and trans regulation in yeasts

Gene expression is regulated both by cis elements, which are DNA segments closely linked to the genes they regulate, and by trans activating factors, which are usually proteins capable of diffusing to unlinked genes基因表达的调控既通过顺式作用元件（cis elements）实现——这类元件为与其所调控的基因紧密连锁的DNA片段，同时也通过反式激活因子（trans activating factors）实现——这类因子通常为能够扩散至非连锁基因的蛋白质