Causes of fragile testes revealed by evolutionary studies of gene expression regulation

果蝇种间杂交种的精子发生缺陷是常见的。事实上，杂交雄性不育比雌性不育进化得更快。为了了解杂交不育是如何如此迅速地出现的，我们对黑腹果蝇睾丸的表达谱进行了表征，发现转录和翻译的基因有明显的聚集趋势。更重要的是，表现出菌株特异性高或低表达的基因也倾向于聚集。可以想象，睾丸转录没有受到严格的控制，因此睾丸拥有许多嘈杂的转录产物。另一方面，通过使用种间杂交，我们获得了证据，表明顺式和反式调控元件之间的杂交不亲和性积累的速度比通常认为的要快得多。综上所述，我们提出调控不亲和性有助于杂交雄性不育的快速进化。

Spermatogenesis defects are frequently observed in interspecific hybrids of Drosophila. Indeed, hybrid male sterility evolves much faster than female sterility. To understand how the hybrid sterility can arise so quickly, we characterized the expression profile of testes of Drosophila melanogaster and found that transcribed and translated genes tended significantly to cluster. More importantly, genes exhibiting strain-specific higher or lower expression also tended to cluster. It is conceivable that testis transcription is not strictly controlled and therefore that the testis possesses many noisy transcripts. On the other hand, by using interspecific hybrids, we obtained evidence that hybrid incompatibilities between cis- and trans-regulatory elements are accumulating much faster than generally considered. Taken together, we proposed that regulatory incompatibilities contribute to the fast evolution of hybrid male sterility.