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。
NOTE 注釋:
1. clone [klEJn] vt. 無性繁殖,克隆
2. obstacle [5CbstEkl] n. 障礙, 妨害物
3. deform [di:5fC:m] v. (使)變形
4. miscarried [mis5kArid] adj. 流產(chǎn)的
5. imprinted [im5printid] adj. 留下烙印的