DESIGNERFOODS

　　化合食物

　　by George Erdosh

　　People think of “genetically altered food”with the same suspicion and distrust that they have when they hear about cloning animals, raising chickens with hormones, or building up muscles with steroids. All interfere with nature. Is this good? Is it safe? Before you make up your mind about genetic alteration, let’s find out what it is.

　　What Is Genetic Alteration?

　　Biotechnology, the science that deals with genetic alteration, is a relatively new discipline that alters a plant on the molecular level to improve it in some way. Let’s get down to this level. DNA (short for deoxyribonucleic acid) is one of the basic elements in the cells of every living organism, whether they’re from a mushroom or a dinosaur or a human being. DNA provides the building blocks for your body’s genes. Each gene regulates a trait, like the color of your hair, the shape of an elephant’s trunk, or the sweetness of Chinese peas.

　　Scientists can clip a gene from the DNA of one plant and splice it into the DNA of another plant that’s genetic alteration. Of course, it really isn’t as simple as it sounds. But it does work. The question is, Why do it? Here's an example. The strawberry plant is very sensitive to frost. If it’s unprotected in the field and the temperature drops below freezing, that’s the end of your strawberry crop for this year. So you don’t plant your strawberry plants until you are sure there will not be any more frost.

　　But parsley is resistant to frost. It has built-in antifreeze chemicals that protect it from even heavy frost. If the biotechnologist can splice that gene responsible for producing antifreeze chemicals from the parsley into the strawberry plant, the farmer may be able to start planting strawberries three or four weeks earlier in the spring. We’ll have an earlier crop and longer harvest season.

　　Another example is plants' resistance to disease or pests or drought. Some have it, others don't. The ones that don't may benefit from the ones that do by genetic alteration.

　　Changing Plants Isn't New

　　Ever since humans started growing plants some 10,000 years ago instead of picking them in the wild, farmers have improved plants a great deal. The original apples were the size of crabapples, bitter and flavorless; green peppers were cherry-size and so hot that you were in agony should you bite into one. Wild strawberries were no bigger than M&Ms. Without altering some of our plants, we couldn't have survived and supported today's huge world population.

　　The difference between then and now is the length of time that is necessary to develop new crop strains. Back then, farmers always selected and saved the best of their crops to plant as the next year's seeds. This strategy of repeated selection for specific food qualities allowed food plants to slowly improve until we got large, juicy, tasty apples, sweet green peppers, and strawberries that take more than one bite to eat.

　　Today's genetic alteration makes the same kinds of changes, but the results come in a few years.

　　How Safe Is Genetic Alteration?

　　No one knows for certain how safe genetic alteration is. Scientists believe that most alterations are as safe as the traditional method of slow plant breeding for improved food plants. There are genetically altered products that we have been using for at least 10 years without ill effect. Bakers' yeast that produces more bubbles and a cheese enzyme to produce cheese are two examples.

　　There are many, many genetically altered products ready for your supermarket or waiting for government approval: potatoes with properties that allow them to absorb less fat in the french fryer, rice that has higher nutrition, seed oil that is less harmful for our overweight bodies, celery and carrots that stay crisp longer, and coffee with better flavor and less caffeine.

　　What will your children be reaching for in the supermarket someday? Will it be the glow-in-the-dark icing now being developed (containing genetically engineered algae), or perhaps "all natural" foods will once again be the rage. The fact is that some of us may never be comfortable with "designer food" . After all, it just isn't au naturel! Fortunately, our supermarkets still offer fare for the less adventurous.

　　人们对转基因食品充满了怀疑和不信任。就像他们听到克隆动物、用激素养鸡，或用类固醇增加身体的肌肉时所做出的反应一样。所有的这些做法扰乱了自然规律。这些做法好吗？安全吗？在你对转基因的做法下结论之前，让我们先了解它是什么。

　　什么是转基因

　　生物技术是研究基因改变的科学，也是一门比较新的学科。其研究目的是要在分子层次上改变植物的基因，从而在某些方面改进植物。现在让我们来看一看植物的分子层。DNA（全称是脱氧核糖核酸）是任何有机体细胞内的基本元素之一，不论这些细胞来自蘑菇、恐龙还是人类。DNA为你身体的基因提供了构建材料。每一种基因掌控一种特征，比如你头发的颜色、大象鼻子的形状或者荷兰豆的甜度。

　　科学家能够剪下一种植物DNA中的一个基因并把它嫁接到另一种植物的DNA上。这就是转基因。当然，实际情况并不像我们听上去的那样简单。然而，这样做的确可行。问题是：这样做的目的是什么呢？这里有一个例子，草莓类植物非常怕霜。如果这种植物不加任何保护地生长，并且温度降到了摄氏零度以下，那么你今年草莓的收成就会化为泡影了。因此，只有当你确信霜降不会再来以后，再去种草莓。

　　另一方面，欧芹对霜有很强的抵抗力。它自身就有一种防冻的化学物质，可以使它免受强霜冻的伤害。如果从事生物技术的科学家能够从欧芹中把制造防冻物质的基因转接到草莓上去，农民也许就能够在春天提前三至四周开始种草莓。这样，我们就会有早一些的收成和更长的收获期。

　　另外一个例子涉及植物对疾病、害虫或干旱的抵抗力。有些植物有这种抵抗力，有些植物没有。通过基因转移，没有这些抵抗力的植物会从有抵抗力的植物那里受益。

　　改变植物并不是新鲜事

　　大约一万多年前，人类开始种植植物，而不像以前那样从野地里拾捡这些植物的果实。从那时开始，农民就已经对植物做了很大的改进。最初的苹果同山楂一样大，苦而无味，青椒同樱桃一样大小，很辣。如果你咬上一口的话，你就会感到极大的痛苦。那时的野生草莓不比巧克力豆大。如果不对一些植物进行改变，我们人类就活不到今天，也没能力养活今天众多的世界人口。

　　现在与过去的区别在于培育出新物种所需要的时间。那时，农民总是挑出他们最好的收成，留下来作来年的种子。这种反反复复挑选特质品种的方法使得植物能够慢慢地改进，直到我们得到又大又好吃并且多汁的苹果、甜味的青椒和一口吃不完的大草莓。

　　今天的转基因做到了同样的改变，但其结果几年之后才会表现出来。

　　转基因有多安全？

　　没有人能够确切地说出转基因到底有多安全。科学家们认为大多数的转基因同传统上为改进植物而进行的缓慢的育种过程一样安全。有些转基因产品我们用了至少10年，并没有不良影响。例如，面包房里产生更多气泡的酵母和做奶酪的奶酪酶。

　　许许多多的转基因产品准备进入超市销售或正在等待政府的审批。这其中包括：在油炸时，吸油更少的马铃薯；营养成分更高的水稻；对过于肥胖的人害处较小的植物油；能在更长时间保持香脆的芹菜和胡萝卜；口味更好而咖啡因含量更少的咖啡。

　　将来某一天，你的孩子在超市里会想要什么呢？会是开发之中的能在黑暗中发光的糖霜（里面含有转基因的海藻）吗？也许“纯天然”食品又会十分畅销。事实上，有些人可能永远也不会对“合成食物”感到舒服。毕竟这种食物不是纯天然的。幸运的是，我们的超市给顾客提供的还是相对安全的食品。