Since 1996, British scientists have cloned the world’s first father without a father. Strictly speaking, there is no mother’s adult somatic cell clone “Dollyâ€. The word “clone†has spread all over the world. Since then, the cloning fever has risen in various countries, and cloned mice, pigs, cows, rabbits and other animals have appeared. Chinese scientists have also cloned sheep, cattle, precious ornamental fish and so on. Cloning became one of the most important and controversial technological breakthroughs in the 20th century. Although "Dolly" only survived for 7 years and died in a misfortune, it did not eliminate the will and determination of scientists from all over the world to seek breakthroughs in the field of cloned animal research. Not long ago, experts from Chengdu Research Base of Giant Panda Breeding disclosed that the use of frozen somatic cells to clone giant pandas has become possible. With the development of somatic cell cloning technology, even dead giant pandas can be revived. When nature is powerless, manpower may be able to "make up for heaven." Biodiversity Principles and Cloning Technologies Biodiversity is an extremely important concept in nature conservation. It includes genetic diversity, species diversity and ecosystem diversity. Genetic diversity is extremely important for the reproduction of species. As we all know, hybrid rice has high yield and strong disease resistance. However, if a single species always brings in new things, its quality will decline. If the plant species does not improve for a long time, its germplasm will be degraded. Humans have long recognized the danger of inbreeding causing human degeneration. There is a reasoning behind this: For an organism, it has to reproduce, it must have a certain number of genetically different individuals. Below a certain number, it is very likely to cause inbreeding, and then degenerate and extinct; above this number It can produce heterosis, so that this kind of organism can continue to multiply. This is the principle of biodiversity. As a corollary, the cute giant panda has almost reached the edge of extinction. All people concerned about giant pandas have reason to fear that this kind of animal called "living fossils" is probably extinct on a certain day. The reason is that, in addition to the continuous invasion of mankind and the shrinking of its territory, the low breeding ability of giant pandas also makes it difficult for people to thrive. Even under captive conditions, 90% of adult male pandas are still unable to mate, and few pandas breed around the world every year. A wind, a temperature change, a bamboo blossom, and a disaster that may occur at any time will have a devastating impact on this less than 1,000 population. Clone is a transliteration of CLONE in English, referring to asexual reproduction induced by humans. It is the first to act on the breeding of crops. Potatoes and yeasts are all clones. New varieties grafted on different plants are clones. Our body's organs are made up of cells. Tissue cells of various organs can also be cloned after they have been cultivated in vitro. Out of the cherish of giant pandas, at the moment when British cloned sheep came out, many people immediately thought of cloning giant pandas. It can be said that modern biotechnology has brought a great deal of light to the conservation of giant panda resources. The cloning of giant pandas from embryonic clones to somatic cell clones was initiated by the scientists on the basis of the success of embryonic experiments in experimental bananas. First, remove the oocyte (ie, egg) from a female giant panda and remove the nucleus containing the genetic gene, such as removing the yolk from the egg, leaving only the "empty shell." Then, the somatic cells were removed from another giant panda (both male and female), cultured in the laboratory, and implanted in the egg's empty shell from which the nucleus had been removed, allowing it to divide as normal fertilized eggs to form embryos. . The final process was the same as that of obtaining the “test-tube pandaâ€, and the embryo was transferred into the third female panda and bred until the panda was born under normal conditions. Whose child is this panda? Of course it is the one that provides somatic cells, because the somatic cell contains all of its genetic genes, and panda cubs are its "replicas." In 1997, Prof. Chen Dayuan, an animal researcher of the Chinese Academy of Sciences and a cloning expert, first proposed the idea of ​​heterogeneous cloning of giant pandas. A few months later, the Fuzhou Panda Research Center took the lead in cooperating with the Chinese Academy of Sciences in the study of heterogeneous clones of giant pandas. According to this plan, the cloning of giant pandas takes two steps: the first step is to clone the early giant panda embryos; the second step is to move these embryos into the uterus of the mother's mother and make them implanted until the red pandas are produced. After several trials, the researchers removed somatic cells from a female giant panda and implanted them in the egg cells of the rabbit that had removed the nucleus. Six months later, this experiment made a breakthrough, and both cells began to divide and reorganize, thereby creating a group of early embryos. This achievement means that the first step in cloning giant pandas has been successful. However, the real test is the second step in the heterogeneous cloned giant panda plan, which uses another animal as the “acting mother†to develop early panda embryos into a new panda individual in their womb. But each animal's development program is determined by its own genetic code. If it is hard to put an "early giant panda embryo" into the rabbit's uterus, how the two animals' respective DNA have been well-prepared and their respective development programs are harmonized is the real problem facing the cloning technology. It is worth noting here: the difference between embryo cloning and somatic cell cloning. Embryos are formed after the fertilization of both sexes. Embryo cloning is actually the time when an embryo grows to many cells. It is then divided into one cell and cloned with his cell nucleus. The biggest advancement in China is the use of somatic cells for cloning without the use of embryonic cells. Somatic cell cloning has taken a big leap from biology. Generally speaking, somatic cells cannot develop into individuals, but the "Dolly" technology solves them. This problem, the important result it brings, is that we can clone ourselves and we don't need sex. Academic debate on cloning protects giant pandas, do you want to clone? Does cloning destroy biodiversity? The academic debate represented by Professor Chen Dayuan and Prof. Pan Wenshi can be described as diametrically opposed. The opinion expressed by Chen Dayuan was: Actively planning the giant panda cloning experiment. For endangered species, protecting their genetic diversity and preventing their extinction are prerequisites for biodiversity conservation. If some animals do not use artificial breeding, they are likely to be extinct long time ago, such as the Chinese elk and the Middle Eastern Arabian antelope. Therefore, it is meaningless to talk about biodiversity without thinking about species extinction. The key to protecting endangered animals is not to use artificial breeding, but to use artificial reproduction methods to save them. Cloning is one of the alternatives. Although similar genes are found in the same species, they do not have exactly the same genes. Protecting each individual's gene bank is the minimum task of protecting genetic diversity. Cloning is the complete replication of an individual's genes. The individual does not die by cloning itself, and the cloned individuals can still participate in natural reproduction. Therefore, it is inappropriate to say that cloning would reduce the biodiversity of giant pandas. According to Prof. Pan Wenshi, director of the Research Center for Giant Pandas and Wildlife Conservation at Peking University, he is actively involved in the field conservation of giant pandas and against the cloning of giant pandas. There are currently three methods of breeding animals in the biological community: natural mating, artificial insemination and the use of cloning techniques. Which method can best increase the number of pandas? Pan Wenshi believes that natural mating is the best, but the artificial insemination technology is also very successful for the giant pandas in the zoo. These two methods at least enable individuals of the giant panda to obtain two sets of genes from the father and the mother. Genes maintain genetic diversity. However, cloning technology cannot increase the evolutionary process of giant pandas and is time-consuming and laborious. In addition, due to the small number of such national treasure animals, we cannot and do not allow experiments on them. For example, how many days do the fertilized eggs have to float in the uterus of giant pandas? At present, humans are still unable to master the tests. This time is the key to the success of cloning technology. Regarding the cloning method of “the egg or adult cell comes from the giant panda and the female mother is also a giant pandaâ€, Pan Wenshi believes that a giant panda that can successfully breed should give up the fertility opportunity to raise a cloned embryo with little chance of success. This is against the goal of protecting giant pandas. Even Professor Zhang Anju, who supports the study of animal embryo cloning, said that the clone of an identical animal simply means an increase in the number of individuals, which does not reflect biological diversity. This may be a disaster for the biosphere. If the giant panda were to be cloned to continue its descendants, it would be just a product of mankind, just like a table or a teacup, except that it was alive and could be a joy to humanity. Further, if the biosphere needs cloning to sustain, then it will lose its soul. In this sense, it means the death of the biosphere. Wang Daxuan, a panda researcher at Peking University, also believes that cloning is meaningless to save the increasingly rare pandas. Because even if we can clone a few giant panda individuals, they are either not long-lived or not very healthy. Recent studies have shown that cloned mice and other types of cloned animals have many abnormalities, including obesity, pneumonia, liver dysfunction and premature death, and these symptoms are only the tip of the iceberg. Regarding the issue of "replication" and "wildness", in theory, cloning can fundamentally solve the unrelenting worries of the giant panda and all the endangered animals and ensure their children and grandchildren can continue to be sustainable. On the other hand, it means that people can create rare animals according to their own needs. In this case, maybe one day, you can bring a giant cat like a cat or a dog and bring it home as a pet. . If it's dead, it doesn't matter. Just clone another one. However, from a philosophical point of view, no species will ever live on the earth. It will always change and will always be replaced by new species. Pandas are no exception. Prof. Pan Wenshi believes that the best way to save an endangered species is to protect the integrity and stability of the community in which it lives, and the genetic diversity of the species. In protecting giant pandas, the last position we must hold today is to preserve those that are full. Wild population of free life. Cloning is just a copy of a set of genes. It is impossible to increase the diversity of genes and therefore it is impossible to achieve the ultimate goal of protecting giant pandas. Here, survival and death have become twin brothers. In fact, mankind has already fallen into a quagmire. We use the destruction of animal living environment in exchange for economic development, and use the funds and technology obtained through economic development to save them. We are the destroyers of animals, and we now serve as their savior. In this case, let practice test the theory of humans! All kinds of cloned animals, the frog frog, was the first animal to be used for cloning experiments. However, this cloning technique is different from the technique of cloning "Dolly". It is not really a cloning. The former is from the embryo to the late stage of development. The nuclei were extracted, while the latter were taken from the somatic cells. Although the cloning of embryonic cells was relatively easy, the scientists' first cloning experiment failed, and the egg cells that received nuclear transfer were not developed. In 1970, British biologists tried cloning in the same way. As a result, frog eggs developed into fleas, but they died after they started eating. â– Sheep's first embryo The cloned sheep were introduced as early as 1984, but cloning research was still at a low point. Few people thought that somatic cell cloning was feasible, so the birth of somatic cell clone sheep "Dolly" shocked the world It is hailed as one of the most important and controversial technological breakthroughs of the 20th century. Dolly Goat was born on July 5, 1996. A lamb was born in 1998 and was euthanized on February 14, 2003 due to a lung infection. It will be recorded in history as one of the noblest sheep in the world. . The first somatic cell clone in China was called Yangyang. It was born on June 22, 2000. It was born twice in August 2001 and February 2003. It was a pity that the second one died of too weak constitution. â– The first murine clone of a mouse was Karenina, born on October 3, 1997. Different from the cloned sheep Dolly, scientists from Japan, the United Kingdom, the United States, and Italy adopted new technologies to increase the success rate of cloning, and they have now cultivated many cloned mice and obtained cloned clones. Second and third generation cloned mice. The birth of the somatic cell clone mouse also announced that the previous question about the "Dolly" sheep identity and cloning technology could be over. â– Niu "Nengdu" and "Kaga" are the earliest two somatic cell cloned cows. They were born on July 5, 1998. Their names are derived from the place names of the birthplace of Ishikawa Prefecture in Japan. Although the two cows had been born prematurely for nearly 40 days, they had normal development. Their “mother†had no abnormal reaction on the day of childbirth, but she lost her appetite the next morning and died in the afternoon. The success of cloned cattle has shown that this technology can be used to bred batches of excellent or special-purpose livestock and protect endangered species. â– Monkey In all currently cloned animals, monkeys are genetically closest to humans. In January 2000, American scientists claimed that for the first time they successfully cloned a primate—a cloned monkey named “Tytraâ€. The cloned monkey uses the technique of embryo cell cloning. Scientists repeatedly experimented 13 times. Only "Tytra" was fortunately born. Scientists say that these cloned monkeys will be used for the study of human diabetes and Parkinson's disease. â– Pig somatic cell clone After the birth of sheep and cloned mice, the scientists planned to clone the pig. Pigs are prolific, and their organs are closer in size and function to human organs. It is believed that the combination of transgenic technology and cloned pig technology may allow large-scale breeding of transgenic cloned pigs, which can be used to obtain organs suitable for transplant surgery and bring hope to thousands of patients waiting for organ transplants. The first batch of somatic cell clones consisted of 5 pigs and was born on March 5, 2000. â– Cats In early 2002, the world’s first somatic cell clone cat was born and named CC. CC's fur color is very special, and its gray-white coat does not look like its mother, or its genetic mother. It is not easy for CC to come to this world. Scientists have experimented 188 times before they succeeded. â– Rabbits Because it is difficult to grasp the timing of rabbit egg activation and attachment, cloning rabbits is much more difficult than cloning other mammals. In order to successfully clone rabbits with somatic cells, the scientists conducted several experiments and a total of more than 2,000 transgenic egg cells were cultivated, but only six were finally successful in 2002, and two of them died during lactation.
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