英語沙龍十年合集珍藏版第三輯Cloning1) Humans May Have It Easier

所屬教程:英語沙龍十年合集珍藏版第三輯

瀏覽:

手機(jī)版

掃描二維碼方便學(xué)習(xí)和分享

00:00

MP3下載文本下載

Cloning¹⁾ Humans May Have It Easier

Most scientists agreed that cloning an entire human being －－besides being morally question－able －－was fraught with technical obstacles²⁾．After all，research into animal cloning has already shown that there are hundreds of failures，including many badly deformed³⁾ creatures that were usually miscarried⁴⁾．

Now comes word that it might be easier to clone humans than was previously believed．People have a genetic quirk that might pr event some of the developmental deformities associated with animal cloning．One gene，called IGF２R，is normally imprinted⁵⁾ in sheep，cows and mice but not in humans．Human clones would always inherit nonimprinted IGF２R genes，so t here would be no chance of a mix－up and，their growth would be normal．But what of the other４９or so imprinted genes？No one knows what trouble they might cause．So the fact that humans have one less imprinted gene than mice，sheep or cows means that human cloning might be marginally easier，but not necessarily safer．

克隆人類也許更容易

許多科學(xué)家都認(rèn)為克隆一個(gè)完整的人---除了在倫理上令人懷疑外---還存有許多技術(shù)障礙。畢竟，對(duì)動(dòng)物克隆的深入研究已經(jīng)表明有上百個(gè)失敗案例，包括許多因嚴(yán)重畸形而通常流產(chǎn)的動(dòng)物。

現(xiàn)在有消息說克隆人可能比以前所認(rèn)為的要容易。人類有一種基因突變可以防止一些與動(dòng)物克隆相關(guān)的發(fā)育畸形。一種叫做IGF２R的基因，通常遺傳到綿羊、奶牛和老鼠，但不在人類身上。人類克隆一直是繼承非遺傳性的IGF２R基因，所以不會(huì)造成混亂，他們的發(fā)育將是正常的。但是另外約４９個(gè)遺傳基因會(huì)怎樣呢？沒有人能夠知道他們會(huì)造成什么樣的麻煩。所以人類比老鼠、綿羊和奶牛少一個(gè)遺傳基因這一事實(shí)意味著克隆人類可能稍容易一些，但并不一定更安全。