美国科学60秒 SSS 2013-07-30
时间:2013-08-29 03:01:24
搜索关注在线英语听力室公众号:tingroom,领取免费英语资料大礼包。
(单词翻译)
This is scientific american 60-secs science. I'm Sophy Bushwick. Got a minute?
It takes a white
chromosome1 to make a man, but that does't mean its counterpart, the x-chromosome, plays no part. In fact it has a big role in making
sperm2.
To study x evolution, experts first sequence human chromosome more accurate than it ever before. Then they compare the code to that of a mammal whose
evolutionary3 lineage spit from ours about 80m yrs before, the mouse. It turns out that human and mice share 95% of their x-
genes4, this finding was no surprise.
In the 1960s, biology S.O. suggests that the x-chromosome would evolve slowly and almost remain similar in most mammalia species. But something did change over evolutionary time, or rather 144 things. 144 human x-chromosome genes had no counterparts in
mince5 and these genes seems to be constantly developing. Many of the genes remained
domain6 in female, only become productive in tissues involved in
sperms7 production. Clearly, the ex-chromosome exceeds its feminine responsibilities, which is excellent news for male fertility.
分享到: