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

果蝇种间杂种中经常观察到精子发生缺陷。事实上，杂交雄性不育比雌性不育进化得快得多。 为了理解杂交不育性如何如此迅速地出现，我们表征了果蝇睾丸的表达谱，发现转录和翻译的基因倾向于显着聚类。 更重要的是，表现出菌株特异性较高或较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控制，因此睾丸具有许多嘈杂的转录本。 另一方面，通过使用种间杂交，我们得到的证据表明，杂交不相容性之间的顺式和反式调节元件的积累速度比通常认为的要快得多。 综上所述，我们认为调控不亲和性有助于杂种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.