科學(xué)家發(fā)現(xiàn)了一個新的在自然種群中形成生殖隔離的機(jī)制，這個機(jī)制雖然被提出過,，但是在自然界這是首次被觀察到,。一個果蠅的對生殖至關(guān)重要的基因從一個染色體跳到另一個染色體上,，導(dǎo)致雜交雄性喪失了生育能力。John P. Masly和同事步達(dá)爾文的后塵,，尋找使使一個物種進(jìn)化為兩個的原因,。DNA序列的變化通常對這個過程有幫助。比如,，當(dāng)馬和驢交配時,，它們生下沒有生育能力的騾子，是因為這兩種動物的遺傳不同,。這些不能生育的騾子于是“生殖隔離”了馬和驢,。研究人員在實驗室中交配兩種果蠅：Drosophila melanogaster和D. simulans，這兩種果蠅大約是在300萬到500萬年前分離出來的,。研究人員意外地發(fā)現(xiàn),，在那個時期，對精子的能動性有關(guān)鍵作用的JYAlpha基因從D. melanogaster的4號染色體跳到D. simulans的3號染色體,。許多缺少JYAlpha的雄性雜交果蠅沒有生育能力,，表明在這個情況下，生殖隔離是由基因轉(zhuǎn)位,，而不是基因DNA序列的變化,，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.
