Who can help introduce the achievements and prospects of genetic engineering?

Genetic engineering technology and prospect

Genetic engineering refers to inserting nucleic acid molecules into viruses, plasmids or other vector molecules in vitro to form a new combination of genetic materials, which can be integrated into host cells without such molecules before and can be propagated continuously and stably. In layman's terms, people can artificially design and transform genetic material and other jobs that people want to do. Cloning organisms, transforming organisms, diagnosing and treating diseases and so on. . Generally speaking, genetic engineering refers to genetic engineering at the gene level. It is to artificially extract the genetic material of a donor organism-DNA macromolecule, cut it in vitro with an appropriate tool enzyme, connect it with the DNA molecule as a carrier, and then introduce it into the recipient cell which is easier to grow and reproduce together with the carrier, so that the foreign genetic material can "settle down" in it and be reproduced and expressed normally. This definition shows that genetic engineering has the following important characteristics: first, exogenous nucleic acid molecules can propagate in different host organisms, can cross the barrier of natural species, and put genes from any organism into new organisms, which can be independent of the original organisms. This ability is the first important feature of genetic engineering. The second feature is that a small DNA fragment is amplified in a new host cell, thus obtaining a small number of DNA samples.

Genetic engineering refers to inserting nucleic acid molecules into viruses, plasmids or other vector molecules in vitro to form a new combination of genetic materials, which can be integrated into host cells without such molecules before and can be propagated continuously and stably. In layman's terms, people can artificially design and transform genetic material and other jobs that people want to do. Cloning organisms, transforming organisms, diagnosing and treating diseases and so on. . Generally speaking, genetic engineering refers to genetic engineering at the gene level. It is to artificially extract the genetic material of a donor organism-DNA macromolecule, cut it in vitro with an appropriate tool enzyme, connect it with the DNA molecule as a carrier, and then introduce it into the recipient cell which is easier to grow and reproduce together with the carrier, so that the foreign genetic material can "settle down" in it and be reproduced and expressed normally. This definition shows that genetic engineering has the following important characteristics: first, exogenous nucleic acid molecules can propagate in different host organisms, can cross the barrier of natural species, and put genes from any organism into new organisms, which can be independent of the original organisms. This ability is the first important feature of genetic engineering. The second feature is that a small DNA fragment is amplified in a new host cell, so that a small number of DNA samples can "copy" a large number of DNA, and a large number of absolutely pure DNA molecular groups are not polluted by any other DNA sequences.

After the rise of genetic engineering in the 1970s, after more than 20 years of development, it has made amazing achievements, especially in the last decade. The application of gene transfer and gene amplification not only brings unprecedented changes to the research of life science, but also shows bright application prospects in practical application fields such as medicine and health, agriculture and animal husbandry, food industry and environmental protection.

Genetic engineering, medicine and health

At present, genetic engineering is widely used in the field of medicine and health, mainly including the following two aspects.

1. Production of genetically engineered drugs such as insulin, interferon and hepatitis B vaccine. Genetically engineered drugs are a major breakthrough in the pharmaceutical industry.

2. that genetic engineer technology used for gene diagnosis and gene therapy can also be directly use for gene diagnosis and therapy. . At present, many viruses, such as enterovirus and herpes simplex virus, have been detected by genetic diagnosis.

Gene therapy is to introduce healthy foreign genes into gene-deficient cells to achieve the purpose of treating diseases. Such as malignant tumor, AIDS, cardiovascular disease and diabetes, can also be overcome by human beings.

Genetic Engineering and Agriculture, Animal Husbandry and Food Industry

The application of genetic engineering in agriculture and animal husbandry production is mainly to cultivate new varieties of animals and plants with high yield, high quality or special use. The application of genetic engineering in agriculture is mainly manifested in two aspects. First of all, high-yield, stable-yield and high-quality crops are obtained through genetic engineering technology. For example, the protein content of food crops can be improved by genetic engineering. Secondly, through genetic engineering, various new crop varieties with stress resistance are cultivated. There are many kinds of bacteria in nature, and almost all kinds of resistance needed by plants can be found in bacteria, such as insect resistance, virus resistance, herbicide resistance, saline-alkali resistance, drought resistance and high temperature resistance. If these resistance genes are transferred to crops, the characteristics of crops will be fundamentally changed.

The application of genetic engineering in animal husbandry also has broad prospects. Scientists combine some specific genes with viral DNA to form recombinant DNA, and then transfer the recombinant DNA into animal fertilized eggs through infection or microinjection technology. Animals developed from this fertilized egg can obtain all kinds of excellent qualities that people need, such as disease resistance, high birth rate, high milk yield, high quality fur and so on.

Genetic engineering can also open up new food sources for human beings.

Genetic engineering and environmental protection

The method of genetic engineering can be used for environmental monitoring, genetic engineering and purification of polluted environment. Pesticides that cause environmental pollution and try to recycle industrial waste through genetic engineering. These are all promising research topics.

(1) In industry, microbial fermentation has many advantages over agricultural production, so it has become a promising direction of agricultural development. To achieve this goal, genetic engineering will be the most effective means. For example, some people imagine and are trying to transfer the related genetic genes of antibiotic-producing bacteria actinomycetes or molds to bacterial cells with shorter fermentation time and easier culture; Transferring the gene that produces insulin from animals or humans into yeast or bacterial cells; Introducing a gene for producing silk protein into bacterial cells; Transferring genes that produce antibodies, interferons, hormones or interleukins from humans or animals to bacterial cells; Transfer the surface antigen genes of different viruses into bacterial cells to produce various vaccines; Improve the yield of various amino acid fermentation bacteria through genetic engineering; Constructing engineering bacteria that decompose cellulose or lignin to produce important metabolites; And the work of cultivating high-yield bacteria such as industrial and medical enzyme preparations by using gene recombination technology.

If this kind of work is successful, its economic benefits will be very significant. For example, at present, only 3-4g insulin can be extracted from 100000g pancreas, and the same amount of products can be obtained by using several liters of fermentation broth for fermentation production with "engineering bacteria". During the period of 1978, two laboratories in the United States cooperated to make the research on insulin production by Escherichia coli in rats successful. Subsequently, it was reported that the experiment of synthesizing human insulin by Escherichia coli was successful through genetic engineering. In the laboratory, they have combined the synthetic genes of human insulin A chain and B chain into different plasmids of E.coli and then transferred them to bacteria. This recombinant plasmid can be replicated and expressed normally in E.coli cells, so that "engineering bacteria" strains with A-chain and B-chain genes can produce A-chain and B-chain of human insulin respectively, and then these two chains can be connected into active human insulin through disulfide bonds in vitro by artificial methods. In addition, in 1977, foreign countries have used genetic engineering technology to make Escherichia coli produce an animal hormone called growth hormone releasing factor "SRIH" (a tetrapeptide, which can inhibit the release of other hormones and treat diabetes, etc. ). Originally, it was extracted from the pituitary gland of sheep. After 500,000 sheep were slaughtered, only 5mg of the product could be extracted. Now it only needs 10L.

In recent years, there are more and more examples of using genetic engineering to obtain such products, especially polypeptide substances, such as enkephalin (an analgesic substance in the brain), ovalbumin (that is, "OV" and peptide 389), interferon (used to treat viral infections), thymosin α- 1 (which has the function of immune adjuvant and can treat cancer), hepatitis B vaccine and hepatitis B vaccine. Chinese scholars are also catching up, and have made a series of encouraging achievements in genetic engineering research such as enkephalin, α-interferon, γ-interferon, human growth hormone, hepatitis B vaccine, vaccinia virus strain containing hepatitis B surface antigen gene and penicillin acylase.

(2) Application of genetic engineering in agriculture Genetic engineering is also widely used in agriculture. It is estimated that by the end of this century, the value of plant genetic engineering products listed every year is equivalent to ten times that of pharmaceutical products. Several main application fields include: ① Transfer the nitrogen-fixing genes of nitrogen-fixing bacteria into rhizosphere microorganisms or tumorigenic microorganisms growing in important crops, or simply introduce them into the cells of such crops to obtain new crop varieties that can independently fix nitrogen. According to estimates, using the former method, its research funding is only 1% to 1% of the same effect achieved by developing nitrogen fertilizer industry through conventional methods; The latter method is more convenient, and its cost is less than one thousandth of the above; (2) Recombinating the genes of lignin-decomposing enzyme or cellulose-decomposing enzyme into yeast, so that yeast can make full use of abundant and sustainable cheap raw materials such as rice straw and sawdust to directly produce alcohol, which is expected to open up inexhaustible sources of new energy and chemical raw materials for human beings; (3) Improve and cultivate new varieties of crops, livestock and poultry, including improving photosynthetic efficiency and various resistance gene engineering (salt-resistant, drought-resistant and disease-resistant genes of plants and antifreeze protein genes of fish).

Analytical procedures for evaluation and analysis (case-by-case procedures).

The starting point of the management of genetically modified organisms and their products in all countries of the world is basically to protect human health. Agricultural production and environmental safety are carried out at the same time, so as to promote its development and create the greatest benefits for mankind. Mainly divided into three categories: ① loose management mode. Represented by the United States and Canada, its management principle is that there is no essential difference between genetically modified organisms and their products and non-genetically modified organisms and their products. The United States is the largest producer and exporter of genetically modified crops in the world. The agencies that manage the safety of biotechnology and genetically modified foods include the US Food and Drug Administration (FDA), the US Department of Agriculture (USDA) and the Environmental Protection Agency (EPA). FDA and USDA price results show that American sales use labels. The FDA believes that scientific evaluation results show that all foods containing biotechnology ingredients sold in the United States are as safe as ordinary foods, and the public should continue to build confidence in genetically modified foods. ② Strict management mode. The management principle of EU countries is to assume that genetically modified organisms and their products are potentially dangerous, and all related activities should be strictly managed, and new regulations should be formulated for genetic engineering technology. 1997 17 on may 5th, the European parliament passed the resolution of "new food regulations", which stipulated that the genetically modified products listed by EU member states must have genetically modified labels, including all genetically modified foods or foods containing genetically modified ingredients. The contents of the label should include: the source of genetically modified organisms; Sensitization; Ethical considerations; It is different from traditional food in composition, nutritional value and efficacy. September 1998, 1 1, EU Supplementary Labeling Guidelines, which stipulate that foods transferred to beans and corn (currently without food additives, such as soybean lecithin) must be labeled; If the raw materials and genetically modified ingredients of the food are not added during the processing, it is marked as non-genetically modified food. On June, 2000, 65438+ 10 1 1, the European Union published Regulation 50/2000 in its official gazette, which targeted at some lax management models. In addition to the above countries, the management regulations and measures of most countries in the world are gradually being established, which are neither loose nor strict.

For the development of transgenic technology, on the one hand, the Chinese government takes measures to encourage, support and promote international and domestic research and development, and opposes restricting the development of biotechnology or building trade barriers under the pretext of biosafety; On the other hand, the universality of biosafety issues. Pay great attention to the potential, long-term and seriousness, resolutely oppose the pursuit of commercial interests and local interests, and fully consider many social and economic factors such as ethics and religion to do a good job in biosafety management with a responsible attitude towards the long-term interests of all mankind and future generations. 1992 The Ministry of Health promulgated the Measures for Hygienic Management of New Resource Foods. It is clear that the production of genetically modified foods lacks approval and labeling methods. 65438-0993 The former State Science and Technology Commission promulgated the Measures for the Safety Management of Genetic Engineering, which requires the safety evaluation of genetically modified organisms and the formulation of safety control methods and measures. From 65438 to 0996, the Ministry of Agriculture promulgated the Implementation Measures for Safety Management of Agricultural Biogenetic Engineering, and carried out experimental research on genetically modified crops from the perspective of protecting China's agricultural genetic resources, agricultural bioengineering industry and agricultural production safety. Intermediate research, environmental release or commercial management. To this end, the Ministry of Agriculture has established the Safety Management Office of Agricultural Biogenetic Engineering and the Safety Committee of Agricultural Biogenetic Engineering in general agriculture. Since 1997, it has been managed by domestic genetic engineering research, intermediate research, environmental release or commercialization. Therefore, the Ministry of Agriculture has established the Safety Committee of Agricultural Biogenetic Engineering, which has accepted the safety evaluation and approval of genetically modified plants, animals and microorganisms engaged in genetic engineering research, experiments, environmental release and chemical production in China since 1997, and conducted strict safety evaluation on the commercial production of genetically modified organisms and their products. Up to 200 1, the Ministry of Agriculture has accepted more than 700 applications for safety assessment of agricultural genetically modified organisms 10.

Safety of long-term effects of genetically modified foods

Genetically modified crops were planted in a large area 10a, and the number of people eating genetically modified food exceeded 654,380+0 billion. So far, there are no examples of unsafe genetically modified foods. The long-term effect of genetically modified food safety can be seen from this. Therefore, we should take a scientific attitude towards the long-term effects of genetically modified food safety and adhere to the principle of substantial equivalence of safety. At present, China has cultivated a number of transgenic crop varieties, some of which have been tested in the field for many years, and the conditions for industrialization are ripe. We should seize the opportunity to further promote industrialization to meet the people's growing consumer demand.

conclusion

(1) Using transgenic technology, we can produce foods that are more nutritious, more suitable for storage and can promote health, which is beneficial to consumption in both industrialized and developing countries. It is of great significance to alleviate or alleviate the food crisis. We should take concerted action in a planned way to study the positive and negative effects that transgenic technology may bring to the environment and human beings, and compare this effect with that of conventional agricultural technology currently used, that is, evaluate it on the principle of "substantial equivalence".

(2) Responsible genetic modification of animals and plants or the use of transgenic technology is neither new nor harmful in nature. Compared with transgenic technology, traditional genetic breeding lacks flexibility and accuracy, so it lacks predictability, and its risk is by no means lower than transgenic technology.

(3) Exaggerating the potential dangers of genetically modified food and lacking research-based speculation may confuse consumers' understanding of food safety, thus fundamentally hindering the development of genetically modified technology.

(4) The objective risks of genetically modified technology and genetically modified food may become technical barriers to food trade in some countries with backward technology development.

(5) Actively develop transgenic technology and food industry, and strictly supervise technologies and products. The safe development of transgenic technology is undoubtedly leading and will continue to lead a new revolution in biological and agricultural science and technology industries. Therefore, mankind will not worry about food and clothing.

2 Safety of genetically modified food

From 65438 to 0998, the research report of Professor Pupitai of Aberdeen Rotter Institute in the United Kingdom reported that young rats would damage their internal organs and immune system after eating genetically modified potatoes, which was the earliest query to the scientific evidence of so-called genetically modified food [4]. Although the Royal Society announced in May that 1999 had no strong evidence, it triggered a worldwide discussion on the safety of genetically modified foods.

The history of long-term consumption proves that DNA and its degradation products in food have no toxic effect on human body. Any gene is composed of four bases. At present, the composition of foreign genes used in genetically modified foods is no different from that of ordinary DNA, regardless of their sources. In addition, the content of foreign genes in genetically modified foods is very small. For example, if you eat genetically modified tomatoes, the number of foreign genes ingested by the human body should not exceed three. 3×10-4 ~10×10-4 μ g/d, which shows that the number of exogenous genes ingested into human body by eating genetically modified foods is insignificant compared with the number of DNA from other foods that persist in the digestive tract. Therefore, foreign genes in genetically modified foods will not have direct toxic effects on human body.

Possibility of exogenous gene transfer After the genetically modified food is eaten, most of its DNA has already been degraded and inactivated in the stomach and intestines. Will the remaining parts shift horizontally? For example, genetically modified food crops contain antibiotic resistance marker genes. Can genetically modified food be transmitted to and expressed in microorganisms in the intestines of people and animals, thus affecting the efficacy of oral antibiotics on people and animals? This possibility is very small, unless special circumstances need to be considered. Because DNA transfer and integration into recipient cells is a very complicated process, it requires that DNA must be combined with cells and recipient cells must be competent. There is no mechanism to transfer DNA to digestive system microorganisms, so it is unlikely that new genes in genetically modified foods or living genetically modified microorganisms will transfer marker genes to intestinal microorganisms of people or livestock, thus endangering the health of people or livestock.

The food safety of foreign protein should consider its direct toxicity, allergy and side effects caused by the catalytic function of protein. Most genetically modified foods that cause food allergies contain one or more protein. They are relatively stable during processing, cooking and eating. These foreign protein may cause food allergies, especially to children and adults with allergies. It has been reported that people who are allergic to Brazil nuts are allergic after eating soybeans with Brazil nut genes. At present, the foreign genes in genetically modified foods approved for commercial production must be analyzed by related experiments, including chemical composition, content, daily intake and stability in digestive tract. For example, the foreign protein encoded by the foreign gene in transgenic tomato FLAVRSAVRTM has no homology with the known toxic protein [5]. Due to the low content of foreign genes, the number of protein encoded by them is very small, accounting for only 0. 08%, so the daily intake of exogenous protein is no more than 25 ~ 74 μ g/kg d. The results of acute toxicity test on mice with this exogenous protein show that there is no adverse effect when the intake reaches 500mg/ kg body weight. Therefore, from the toxicity of foreign protein, eating transgenic tomato FLAVRSAVRTM will not cause safety problems. In addition, the in vitro simulation test proved that the stability of foreign protein in FLAVRSAVRTM was poor. Under the condition of simulating stomach (pepsin solution is pH 1. 2,37℃), protein was degraded within 65438±00s s. There is no evidence that the polypeptide produced by protein degradation is more toxic than other protein [6].

Other safety problems of genetically modified foods Every link in the production of genetically modified foods may have an impact on food safety, and gene pleiotropy is the most difficult to control. In addition, whether transgenic technology can indirectly affect human ecological environment and food chain should really attract people's attention. It has been reported that Bt corn secretes transgenic toxins into the soil, which can stay in the soil for several months by combining with soil particles [7]. In addition, after planting herbicide-tolerant transgenic plants, the use of pesticides increases, and weed plants with strong tolerance can appear for a long time [8]. From the genetic improvement of nutritional components, the types of trace components such as amino acids, carbohydrates and fats and the arrangement order of macromolecules in genetically modified foods have changed, and the content of natural toxins may also change. Therefore, it is necessary to identify the key ingredients of genetically modified food and conventional food in essence to determine whether they are safe to eat.