On the right and wrong of genetically modified food

Introduction: genetically modified foods have been on the market for five years However, in the recent year, the debate on its safety has become increasingly fierce, which has aroused worldwide uproar Governments have also taken measures to limit the listing of genetically modified foods Due to the small amount of genetically modified food on the market in China, the public has not paid attention to this great debate concerning people's health and natural ecological balance The author, referring to the recent reports at home and abroad, wrote this article for the readers What is genetically modified food? Food produced from genetically modified plants, animals or microorganisms (in whole or in part) What is a genetically modified plant, animal or microorganism? Using the method of genetic engineering, i.e using a kind of restriction endonuclease as a scalpel, the helical DNA (deoxyribonucleic acid, the genetic material of animals and plants) molecules in biological cells are cut open, and a section of genes (the basic unit of organism genetics, existing in DNA molecules in cell chromosomes) is selected, Recombining with other related genes is the same as splicing different movie fragments together by movie editors; recombined genes need to be sent back to the organism for function by other methods In this way, the gene of one plant, animal or microbe is implanted into the DNA of another plant, animal or microbe, and the recipient obtains a new characteristic brought by the transferred gene which it can not have naturally, so it is called transgenic plant, animal or microbe At present, most of the genetically modified food comes from plants, so this paper mainly discusses the genetically modified plant food The emergence of transgenic plants, animals and microorganisms is inevitable for the development of biological science Due to the discovery of nucleic acid, the discovery of DNA double helix structure and replication, the analysis of genetic code, the establishment of operon theory, the elucidation of tdna structure and reverse transcriptase, the formation of DNA recombination and sequence analysis methods and other principles and concepts, it provides a theoretical basis for the development of molecular biology; sequencing, electrophoresis of protein, DNA and RNA, Molecular hybridization and PCR (polymerase chain reaction) and various technologies developed from them provide technical possibilities for the emergence of transgenic animals, plants and microorganisms Since then, human beings can carry out genetic engineering breeding for plants, animals and microorganisms according to their own needs, and its benefits are obvious Current situation of genetically modified food the first commercialized genetically modified food in the world is MacGregor flavr SaVR genetically modified extended ripened tomato approved by the U.S government in 1994 Tomatoes, which can be used as both vegetables and fruits, are loved by people from both East and West Unfortunately, it is not easy to store and transport Scientists in the United States first transplanted a gene that can inhibit the softening enzyme in tomato into tomato cells, and developed a storage resistant transgenic extended ripening tomato Its growth period is one week longer than that of ordinary tomatoes, and it can grow until it turns red to mature, reaching the necessary sugar and acidity before picking Such tomatoes can be transported to all parts of the United States without rotting Now the United States is the largest producer and exporter of genetically modified crops in the world About 30 kinds of seeds of genetically modified crops have been approved to be planted in the United States, including corn, soybean, rape and cotton At present, 8 million hectares of farmland in the United States are planted with transgenic "BT" corn (BT is insecticidal protein gene, which can resist the invasion of Lepidoptera insects after introduction of corn - note by the author) Its yield accounts for 1 / 4 of the total yield of corn in the United States The yield of transgenic soybean accounts for 35% of its total yield, while the yield of transgenic cotton accounts for half of its total yield Now, 30 million hectares of farmland in the United States are planted with genetically modified crops It is estimated that the United States can obtain 4 billion US dollars of excess profit every year for only one product of genetically modified corn The economic benefits of transgenic crops can be seen from this Currently, 60% of retail food in the United States contains genetically modified ingredients Professionals predict that in five to 10 years, genetically modified food will flood the entire food supply system in the United States Britain has made the second largest progress in biotechnology research after the United States There are now 500 transgenic crop experimental fields in the UK, with a total area of about 717 acres But up to now, the technology has not been commercialized in the UK All genetically modified crops tested in the UK have been put into commercial cultivation abroad, such as the United States, Canada and Australia China is stepping up the research of genetic engineering and approved the commercialization of transgenic extended ripening tomatoes in the first half of 1997 At the same time, scientists in China have also developed transgenic anti freezing tomato for the first time It is produced by transplanting the anti freezing gene of a cold water fish named "American plaice" living in the cold and temperate zone into the DNA of tomato cells The fish gene and its excellent properties of tomato can be passed on from generation to generation This kind of tomato can survive at - 6 ℃ for several hours, successfully avoiding the injury of low temperature in late autumn and early morning in the north, so that people in cold areas can eat tomatoes Last year, the planting area of insect resistant transgenic cotton in Hebei Province reached 20% of the whole cotton field As a result of saving insecticides and labor, and the output increased by 25%, the income per mu increased by 300 yuan, with considerable economic benefits Other countries are also engaged in the research and application of genetically modified crops, such as Canada approved 18 kinds of commercialization of genetically modified crops, Japan approved 7 kinds, Australia approved 4 kinds, etc The origin and development of the debate on genetically modified food In the summer of 1998, Professor pustaui of the UK's Lloyd's Research Institute said in a TV program that his unpublished experiment proved that the consumption of genetically modified potatoes by young rats would damage the internal organs and immune system Thus in the UK, and then in the world triggered a great discussion on the safety of genetically modified food In May this year, the Royal Society announced that the study of portoy was "full of loopholes", from which it could not draw conclusions on the harmful biological health of transgenic potatoes Nevertheless, it failed to curb the discussion on the safety of genetically modified food in the UK and the world The scale and momentum of the great debate in Britain is unique since the mad cow disease crisis The British government and royal family are involved The British government is an active supporter of genetically modified food, while Prince Charles is a representative of the genetically modified food opposition One of the most important reasons why genetically modified food first caused a stir in the UK is that the shadow of mad cow disease is lingering in the British mind Since cows can cause mad cow disease and infect people after injecting pituitary hormone, how can we guarantee the safety of non pure genetically modified food? At present, the safety of genetically modified crops has become a social problem in Japan, Australia, the European Union, the United States and other countries, Consumer groups have launched a considerable campaign against genetically modified crops and food In the United States, which has the most advanced transgenic technology, the National Academy of Sciences is investigating the safety of genetically modified crops and is expected to make a conclusion soon EU countries decided in June to suspend the cultivation and distribution of genetically modified crops until new regulations were enacted Brazil, a big soybean producer, recently announced that it would temporarily stop producing genetically modified soybeans Relevant departments of the Japanese government also said that they would re study and develop new safety assessment standards for genetically modified crops A paper by John Rossi, a professor of Cornell University in the United States, was published in the May issue of nature, a leading scientific magazine in the UK, which attracted worldwide attention The paper said that the pollen of Bt maize contains toxin, and the beneficial insects such as butterfly larva will not develop well after eating the cauliflower sprinkled with this kind of pollen, and the death rate is particularly high It is reported that the same results have been obtained in the field test conducted in Iowa, USA Scientists believe that Bt gene implantation can make corn produce insect killing substances, which have insect resistance, but also have toxicity, which may have adverse effects on the ecological environment In addition, a paper published in 1996 by the Danish National lissault Institute said that herbicide resistant weeds were produced by breeding herbicide resistant transgenic rapeseed with weeds This shows that the gene produced by transgenic technology can spread to the nature According to the report released by the University of Arizona and other institutions, some insects have been found and will not die if they eat the transgenic crops that are resistant to the toxins produced by the transgenic crops The center for ethics and toxicity of the United States reported that compared with general soybeans, herbicide resistant transgenic soybeans, the anti-cancer component isoflavones decreased These are examples of the insecurity of genetically modified crops Most Americans are familiar with genetically modified crops and foods But recently, with the support of scientific research and environmental protection organizations, many consumers in the United States, like those in Europe and Japan, have begun to oppose genetically modified food In fact, genetically modified food has entered people's daily life Today, from baby milk, bread to soup and pasta, people are unconsciously eating genetically modified food every day From the current test results, most of the genetically modified food is indeed safe, but people's antipathy and security concerns about genetically modified food greatly slow down the speed of entering the market Although transgenic crops are still in the experimental stage in general, biotechnology is the focus of knowledge economy in the 21st century, and the application in the agricultural field is the inevitable trend of agricultural development The focus of the debate on genetically modified food: ① the direct or indirect impact of genetically modified food on human health ② The damage of crops created by transgenic technology to the ecological balance of nature ③ Related ethical issues, etc The safety evaluation of genetically modified food: 1 Necessity: traditional breeding has a history of more than 100 years, but it is only limited to intraspecific or interspecific hybridization No one has ever raised the issue of biosafety evaluation There are essential reasons why biosafety evaluation of transgenic crops is put forward Because transgenic crops are designed according to human intention and purpose through genetic engineering method, which is obviously different from the traditional sexual hybridization method In addition, the gene used in genetic engineering method can come from any organism, and the boundary between species (classes) has been completely broken There is still a lack of understanding about the expression of new combinations and characters in different genetic backgrounds, the impact on the environment and human beings, some of which are even unknown Therefore, it is necessary to evaluate the biosafety of transgenic crops before they are used 2 Evaluation principles: in 1993, the organization for economic development cooperation (OECD) put forward the report "modern biotechnology food safety evaluation: concepts and principles", and put forward the concept of "substantial equivalence" In 1995, who (World Health Organization) applied this principle to the safety evaluation of plant food of modern biotechnology products, and divided the food of genetically modified crops into three categories: ① with "substantial equivalence" with traditional food on the market; ② with "substantial equivalence" with traditional food except for some specific differences; ③ with no "substantial equivalence" with traditional food Considering the diversity of genes, types of genetically modified crops and the environment, the principle of case analysis should be adopted, that is to say, genetically modified crops are not safe or unsafe in general, and should be divided one by one