科学家发现了一个新的在自然种群中形成生殖隔离的机制，这个机制虽然被提出过，但是在自然界这是首次被观察到。一个果蝇的对生殖至关重要的基因从一个染色体跳到另一个染色体上，导致杂交雄性丧失了生育能力。John P. Masly和同事步达尔文的后尘，寻找使使一个物种进化为两个的原因。DNA序列的变化通常对这个过程有帮助。比如，当马和驴交配时，它们生下没有生育能力的骡子，是因为这两种动物的遗传不同。这些不能生育的骡子于是“生殖隔离”了马和驴。研究人员在实验室中交配两种果蝇：Drosophila melanogaster和D. simulans，这两种果蝇大约是在300万到500万年前分离出来的。研究人员意外地发现，在那个时期，对精子的能动性有关键作用的JYAlpha基因从D. melanogaster的4号染色体跳到D. simulans的3号染色体。许多缺少JYAlpha的雄性杂交果蝇没有生育能力，表明在这个情况下，生殖隔离是由基因转位，而不是基因DNA序列的变化，造成的。
英文原文：
Worm Sperm Gives Clue to Male Infertility
U.S. scientists say they have used the nematode worm to identify a raft of new proteins vital for healthy sperm production.
Barbara Meyer and colleagues at the University of California-Berkeley said the quality of sperm chromatin -- DNA packaged with associated proteins -- is known to be an important indicator of male fertility. Meyer's team wanted to identify proteins important for sperm chromatin structure.
They purified those proteins uniquely and richly associated with sperm chromatin in the worm Caenorhabditis elegans and tested their function using RNA interference of all 132 proteins identified.
The team found some were vital for DNA packaging, chromosome segregation and fertility.
In some cases, it's already known that disabling the equivalent proteins in mice causes male sterility. That list of proteins may help identify causes of and diagnostic tests for unexplained male infertility in humans or provide targets for male contraceptives.
The findings appear online ahead of publication in a future issue of the journal Nature.
