Level 4 Reading 3B

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THE BATTLE FOR BIOTECH Genetic engineering (GE) of crops and animals through the manipulation of DNA is producing a revolution in food production. The potential to improve the quality and nutritional value of the food we eat seems unlimited. Such potential benefits notwithstanding, critics fear that genetically engineered products— so-called biotech foods—are being rushed to market before their effects are fully understood. What exactly are biotech foods? Biotech foods are produced from animals and plants that have been genetically altered. Genetic alteration is nothing new. Humans have been altering the genetic traits of plants for thousands of years by keeping seeds from the best crops and planting them the following years, and by breeding varieties to make them taste sweeter, grow bigger, or last longer. In this way, we've transformed the wild tomato from a fruit the size of a small stone to the giant ones we have today. On the other hand, the techniques of genetic engineering are new and different. Conventional breeders always used plants or animals that were related, or genetically similar. In so doing, they transferred tens of thousands of genes. In contrast, today's genetic engineers can transfer just a few genes at a time between species that are distantly related, or not related at all. There are surprising examples: Rat genes have been inserted into lettuce plants to make a plant that produces vitamin C. Moth genes have been inserted into apple trees to add disease resistance. The purpose of conventional and modern techniques is the same— to insert genes from an organism that carries a desired trait into one that does not. Several dozen biotech food crops are currently on the market, among them varieties of corn, soybeans, and cotton. Most of these crops are engineered to help farmers deal with common farming problems such as weeds, insects, and disease. Are biotech foods safe for humans? As far as we know. So far, problems have been few. In fact, according to a 2016 report from the National Academy of Sciences in the United States, "No differences have been found that indicate a higher risk to human health and safety from these GE foods than from their non-GE counterparts." Some GE foods might even be safer than non-GE foods. Corn damaged by insects often contains high levels of fumonisins— toxins that grow in the wounds of the damaged corn. Lab tests have linked fumonisins with cancer in animals. Studies show that most corn modified for insect resistance has lower levels of fumonisins than conventional corn damaged by insects. However, biotech foods have had problems in the past. One such problem occurred in the mid-1990s, when soybeans were modified using genes from a nut.

生物技术之战 作物和动物的基因工程 通过操纵DNA正在引发食品生产的革命。 提高我们所吃食物的质量和营养价值的潜力似乎是无限的。 尽管有这些潜在的好处，但批评者担心转基因产品-- 所谓的生物技术食品在其影响被充分了解之前就被推向市场。 生物技术食品到底是什么？ 生物技术食品是由经过基因改造的动物和植物生产的。 基因改造并不是什么新鲜事。 数千年来，人类一直在改变植物的遗传特征 通过保留最好作物的种子并在接下来的几年里种植， 通过培育品种，使它们尝起来更甜、长得更大或寿命更长。 通过这种方式，我们将野生番茄从一颗小石头大小的水果变成了我们今天拥有的巨大水果。 另一方面，基因工程技术是新的和不同的。 传统的育种者总是使用亲缘关系或基因相似的植物或动物。 通过这种方式，他们转移了数万个基因。 相比之下，今天的基因工程师一次只能在物种之间转移几个基因 他们有远亲关系，或者根本没有亲戚关系。 有一些令人惊讶的例子： 老鼠的基因已被插入生菜植物中，使其产生维生素C。 蛾基因已被插入苹果树以增加抗病性。 传统技术和现代技术的目的是一样的-- 将携带所需性状的生物体的基因插入不携带所需特性的生物体。 目前市场上有几十种生物技术粮食作物， 其中包括玉米、大豆和棉花。 这些作物中的大多数都是为了帮助农民解决常见的农业问题而设计的 例如杂草、昆虫和疾病。 生物技术食品对人类安全吗？ 据我们所知。到目前为止，问题很少。 事实上，根据美国国家科学院2016年的一份报告， “没有发现任何差异表明对人类健康和安全的风险更高 与非转基因食品相比，这些转基因食品的营养价值更高。" 一些转基因食品甚至可能比非转基因食品更安全。 被昆虫破坏的玉米通常含有高水平的伏马菌素-- 在受损玉米伤口中生长的毒素。 实验室测试表明伏马菌素与动物癌症有关。 研究表明，大多数经过抗虫改造的玉米 其伏马菌素含量低于被昆虫破坏的传统玉米。 然而，生物技术食品过去也存在问题。 其中一个问题发生在20世纪90年代中期，当时使用坚果基因对大豆进行了改造。

The modified soybeans contained a protein that causes reactions in humans who are allergic to nuts. While this protein was discovered before any damage was done, critics fear that other harmful proteins created through genetic modification may slip by unnoticed. Moving genes across dramatically different species—such as rats and lettuce—also makes critics nervous. They fear something could go wrong either in the function of the inserted gene or in the function of the host DNA, with the possibility of unexpected health effects. Can biotech foods harm the environment? Most scientists agree that the main safety issues of GE crops involve not people but the environment. Allison Snow, a plant ecologist at Ohio State University, worries that GE crops are being developed too quickly and released before they've been adequately tested. On the other hand, advocates of GE crops argue that some genetically modified plants may actually be good for the land, by offering an environmentally friendly alternative to pesticides, which can pollute water and harm animals. Far fewer pesticides need to be applied to cotton plants that have been genetically modified to produce their own natural pesticides. While applied chemical pesticides kill nearly all the insects in a field, biotech crops with natural pesticides only harm insects that actually try to eat those crops. Can biotech foods help feed the world? "Eight hundred million people on this planet are malnourished," says Channapatna Prakash, a native of India and a scientist at Tuskegee University's Center for Plant Biotechnology Research in the U.S.A., "and the number continues to grow." Prakash and many other scientists argue that genetic modification can help address the urgent problems of food shortage and hunger by increasing crop quantities. Crops can be engineered to grow in areas with harsh, dry climates or in soils not usually suitable for farming. According to the World Health Organization, an estimated 250 million children in the world suffer from vitamin A deficiency. Between 250,000 and 500,000 go blind every year as a result, with half of those children dying within a year of losing their sight. "Golden rice"—a biotech variety named for its yellow color— is thought by some to be a potential solution to the suffering and illness caused by vitamin A deficiency. Other experts, however, claim that the biotechnology industry has exaggerated the benefits of golden rice. "Golden rice alone won't greatly diminish vitamin A deficiency," says Professor Marion Nestle of New York University. "Beta-carotene, which is already widely available in fruit and vegetables, isn't converted to vitamin A when people are malnourished. Golden rice does not contain much beta-carotene, and whether it will improve vitamin A levels remains to be seen." What's next? Whether biotech foods will deliver on their promise of eliminating world hunger and improving the lives of all remains to be seen. Their potential is enormous, yet they carry risks. If science proceeds with caution, testing new products thoroughly and using sound judgment, the world may avoid the dangers of genetic modification while enjoying its benefits.

转基因大豆含有一种蛋白质，会引起对坚果过敏的人的反应。 虽然这种蛋白质是在任何损伤发生之前发现的， 批评者担心，通过基因改造产生的其他有害蛋白质可能会被忽视。 将基因转移到截然不同的物种中，如老鼠和生菜，也让批评者感到紧张。 他们担心插入的基因的功能或宿主DNA的功能可能会出现问题， 可能会对健康产生意想不到的影响。 生物技术食品会危害环境吗？ 大多数科学家都认为，转基因作物的主要安全问题不涉及人，而是涉及环境。 俄亥俄州立大学的植物生态学家Allison Snow， 担心转基因作物开发太快，在经过充分测试之前就被释放。 另一方面，转基因作物的支持者认为，一些转基因植物实际上可能对土地有益， 通过提供杀虫剂的环保替代品， 这会污染水并伤害动物。 棉花植株需要施用的农药要少得多 它们已经过基因改造，可以生产自己的天然杀虫剂。 虽然施用的化学杀虫剂几乎杀死了田里的所有昆虫， 含有天然杀虫剂的生物技术作物只会伤害那些试图吃掉这些作物的昆虫。 生物技术食品能帮助养活世界吗？ “这个星球上有8亿人营养不良，”Channapatna Prakash说， 印度本地人，美国塔斯基吉大学植物生物技术研究中心的科学家。， “而且这个数字还在继续增长。” 普拉卡什和许多其他科学家认为，基因改造可以帮助解决 通过增加作物数量来解决粮食短缺和饥饿的紧迫问题。 作物可以被改造成在恶劣干燥的气候地区生长 或者在通常不适合耕种的土壤中。 根据世界卫生组织的数据， 据估计，全世界有2.5亿儿童患有维生素A缺乏症。 每年有25万至50万人因此失明， 其中一半的儿童在失明后一年内死亡。 “黄金大米”——一种以黄色命名的生物技术品种-- 被一些人认为是解决维生素a缺乏症引起的痛苦和疾病的潜在解决方案。 然而，其他专家声称，生物技术产业夸大了黄金大米的好处。 “仅靠黄金大米并不能大大减少维生素A缺乏症，” 纽约大学的马里恩·内斯特尔教授说。 β-胡萝卜素已经广泛存在于水果和蔬菜中， 当人们营养不良时，它不会转化为维生素A。 黄金大米不含太多的β-胡萝卜素， 它是否会提高维生素A水平还有待观察。" 接下来是什么？ 生物技术食品是否会兑现消除世界饥饿的承诺 改善所有人的生活还有待观察。 它们的潜力是巨大的，但也有风险。 如果科学谨慎进行，彻底测试新产品并使用正确的判断， 世界可以在享受转基因好处的同时避免转基因的危险。

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