Cloning technology has experienced three development periods:
The first period is microbial cloning, that is, thousands of identical bacteria are copied from one bacteria and become a bacterial colony.
The second period is biotechnology cloning, such as DNA cloning.
The third period is animal cloning, that is, cloning a cell into an animal.
In nature, many plants have innate cloning instinct, such as sweet potatoes, potatoes, roses and other cutting propagation plants. However, animal cloning technology has experienced the development process from embryonic cells to somatic cells. As early as 1950s, American scientists took amphibians and fish as research objects and pioneered nuclear transplantation technology. They studied the potential of cell development and differentiation and the interaction between cytoplasm and nucleus. 1986, British scientist Wila Anderson cloned a sheep from embryonic cells for the first time through nuclear transfer, and later some people cloned animals such as cattle, sheep, rats, rabbits and monkeys. China's cloning technology is also quite successful. In the late 1980s, China cloned a rabbit. 199 1 year, Northwest Agricultural University and Development Institute of Jiangsu Agricultural University successfully cloned sheep. 1993 Institute of Developmental Biology of China Academy of Sciences and Agricultural College of Yangzhou University * * * cloned a batch of goats, 1995 South China Normal University and Guangxi Agricultural University cooperated to clone cattle. While cloning monkeys in the United States was successful, Japanese scientists also claimed that they had bred more than 200 "cloned cows". All the cloned animals were successfully transplanted with embryonic cells as donor cells.
1997 In February, Roslin Institute announced the successful cloning of a lamb named Dolly. It uses mammary epithelial cells as donor cells for nuclear transfer, which opens a new page in the history of biological cloning, breaks through the traditional way of nuclear transfer using embryonic cells and makes great progress in cloning technology. The whole cloning process is as follows: scientists selected three ewes, first sucked all the genetic material from the egg cell of one ewe, and then fused the mammary gland cells of another 6-year-old ewe to form an egg cell containing new genetic material, and promoted its division and development into an embryo. When the embryo grows to a certain extent, it is implanted into the uterus of a third ewe, conceived and gives birth to Dolly, a cloned sheep. Dolly is like a 6-year-old ewe that provides breast cells. Dolly sheep is the first animal successfully cloned by somatic cells in the world. The success of Dolly's cloning theoretically shows that highly differentiated cells can restore the zygotic function of fertilized eggs after certain treatment. It shows that cytoplasm can regulate the development of heterogeneous nuclei during development. It provides an important way for the treatment of biological genetic diseases, the cultivation of excellent varieties and population expansion, and plays a certain role in species optimization, endangered animal germplasm preservation and transgenic animal population expansion. Since the successful cloning of Dolly sheep, countries all over the world have aroused strong repercussions, some of which are regarded as good news and some as disasters. The author thinks that we should support the new technology and make a breakthrough in biological cloning. The biggest advantage is that a large number of excellent livestock have been cultivated, which enriches people's material life, reduces costs, improves the efficiency of animal husbandry, and also provides some pharmaceutical raw materials to improve human immune function. Before Dolly the sheep, Roslin Institute had bred a transgenic sheep, whose milk contained raw materials for treating hemophilia, and a company bought it at a high price of 500,000 pounds. If we "replicate" this sheep in large quantities with somatic cells, we can save more patients' lives. In addition, cloning technology can be used to copy a large number of rare animals, save endangered species, adjust the ecological balance of nature and benefit mankind. Why worry? Of course, cloning technology may also bring negative effects. Some cloned animals have identical genes, and infection with a specific virus or other diseases will bring disaster. If there is no plan to clone animals, it will disturb the evolution of species and interfere with the sex ratio. This artificial control of the biological world will bring many unexpected hazards. However, this negative effect can be avoided as long as corresponding research countermeasures are taken and scientific cloning plans are made.
As for human cloning, it is a meaningless research topic. Contemporary biological history has proved that cloning technology can only reproduce creatures with the same appearance characteristics, but can't clone the original talents of the copied people. People's thinking ability is restricted by acquired. Therefore, even if someone can clone people like great leaders and scientists in history, they are just the same in appearance, but they lack the thoughts, temperament and talents of great leaders and scientists. What's the point of such cloning? As for some people who advocate human cloning to obtain human organs for medical organ transplantation, it is also not feasible. Because human cloning is first and foremost a citizen and enjoys human rights. If the clone refuses to donate organs, your inventor can't violate human rights. As for cloning headless people, it is also unrealistic, because clones must eat first and think first. It is impossible without a head. We can't cultivate a headless vegetable, can we? And the most important thing is that human cloning is not in line with the national conditions of the world. Nowadays, the population of the world is expanding rapidly, and many countries implement family planning to control population growth. In this case, how can we spend huge sums of money to do things that violate the laws of social development? As Ruettgers, the German Minister of Research and Technology, said: "Cloning human beings is not allowed and certainly will not happen." Cloning technology has made new progress in Britain, and they have applied it to the cause of human hematopoiesis. The economic background of cloning technology Dr. Ross James, the director of the British PPL company, said: "From the study of Dolly, we know that we can make a transgenic animal from a cell. We are now using this technology to produce the most important component in human blood, namely plasma. " They cooperated with Roslin Institute to study a kind of cattle and sheep with human genes. They first took plasma from animals, and then replaced human plasma. Transgenic cattle and sheep contain important components of human plasma. By raising, cloning or breeding these animals, stable, reliable and relatively cheap blood resources can be obtained. According to statistics, the annual value in Britain can reach 150. It can be said that it has benefited a lot. The prospect of cloning technology is immeasurable.
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/(China Kesen Plant Cloning Network)