Traditional plant breeding involves crossing varieties of the same species in ways they could cross naturally.For example，disease－resistant varieties of wheat have been crossed with high－yield wheat to combine these properties.This type of natural gene exchange is safe and fairly predictable.

    Genetic engineering（GE）involves exchanging genes between unrelated species that cannot naturally exchange genes with each other.GE can involve the exchange of genes between vastly different species， e.g.putting scorpion toxin genes into maize or fish antifreeze genes into tomatoes.It is possible that a scorpion toxin gene，even when it is in maize DNA，will still get the organism to produce scorpion toxin， but what other effects may it have in this alien environment？We are already seeing this problem——adding human growth hormone genes to pigs certainly makes them grow——but it also gives them arthritis and makes them cross－eyed，which was entirely unpredictable.

    It will be obvious，for example，that the gene for human intelligence will not have the same effect if inserted into cabbage DNA as it had in human DNA——but what side－effect would it have？In other words，is GE food safe to eat？The answer is that nobody knows because long－term tests have not been carried out.

    Companies wanting a GE product approved in the UK or USA are required to provide regulatory bodies with results of their own safety tests.Monsanto's soya beans were apparently fed to fish for 10 weeks before being approved.There was no requirement for independent testing，for long－term testing，for testing on humans or testing for specific dangers to children or allergic people.

    The current position of the UK Government is thatThere is no evidence of long－term dangers from GE foods.In the US，the American Food and Drug Administration is currently being prosecuted for covering up research that suggested possible risks from GE foods.

    翻譯：

    傳統(tǒng)的植物培育方法，是依照植物自然雜交的方式，進行相同物種的人工雜交。

    比如，抗病小麥同高產(chǎn)小麥雜交，形成了一種具有雙重特性的新的小麥品種。這種自然的基因交換既安全，又具有相當?shù)目深A(yù)見性。

    基因工程是在彼此毫無關(guān)系的物種之間，相互交換在自然條件下無法交換的基因。它可在有巨大差異的物種之間進行基因交換。比如，將蝎子毒素基因注入玉米，或者將魚防凍基因注入西紅柿。即使在玉米DNA中，蝎子毒素基因依然可能獲得有機組織產(chǎn)生蝎子毒素。但是在這種異質(zhì)的環(huán)境中，這種基因產(chǎn)品會有什么其他作用嗎？我們實際上已經(jīng)發(fā)現(xiàn)這個問題：將人類生長荷爾蒙基因植入豬的體內(nèi)，一定會使豬的生長加速，但是同時也使豬患上了關(guān)節(jié)炎和內(nèi)斜視，而這一切是完全無法預(yù)測的。

    打個比方，人類的智力基因顯而易見在人體DNA內(nèi)和注入卷心菜DNA后的作用是不同的。但將它植入卷心菜中會產(chǎn)生什么樣的副作用呢？換句話說，食用轉(zhuǎn)基因食品安全嗎？沒有人知道答案，因為人們尚未進行長期的測試。

    在英國或者美國，一個公司如果希望其轉(zhuǎn)基因產(chǎn)品獲得批準，它必須向管理機構(gòu)提供本公司轉(zhuǎn)基因產(chǎn)品安全測試的結(jié)果。Monsanto的大豆在獲得批準之前，曾用了10周時間進行喂魚試驗。目前，尚無要求對轉(zhuǎn)基因產(chǎn)品進行獨立測試、長期測試、人體測試，或者就其對兒童及過敏者所造成的特定危險進行測試。

    英國政府目前的態(tài)度是：“尚無證據(jù)表明食用轉(zhuǎn)基因食品存在長期性的危險。”在美國，人們正在起訴美國食品藥品管理局掩蓋轉(zhuǎn)基因食品安全性的研究結(jié)果，這些研究結(jié)果表明，食用轉(zhuǎn)基因食品可能導(dǎo)致危險。

    重點單詞：

    1、breeding　生育，繁殖，培植

    2、resistant　抵抗的、防……的；

    3、yield　出產(chǎn)，結(jié)出，被迫放棄

    例句：These apple trees yield plenty of fruit this year.

    這些蘋果樹今年結(jié)了許多蘋果。

    例句：He was forced to yield the castle.

    他被迫放棄城堡。

    4、property　特性，屬性

    例句：He is studying the medicinal properties of wild plants.

    他正在研究野生植物的藥物特性。

    5、scorpion　蝎子

    6、toxin　毒素

    7、alien　外國的，性質(zhì)不相容的；

    例句：Her behavior is alien to our ethical values.

    她的行為和我們的倫理標準格格不入。

    8、side-effect　副作用