In June, 2000, China Northwest A&F University cloned two "cloned sheep" from adult goat somatic cells, but one of them died of respiratory system dysplasia. According to reports, the cloning technology adopted by the research group is completely different from Dolly's cloning technology, which shows that Chinese scientists have mastered the cutting-edge technology of somatic cell cloning.
Nuclear transplantation experiments between different species have also achieved some gratifying results. 1998, 1 In June, scientists at the University of Wisconsin-Madison in the United States successfully cloned the embryos of five mammals: pigs, cows, sheep, rats and macaques. The results show that the unfertilized eggs of a species can combine with the mature nuclei of many animals. Although these embryos miscarried, it made a useful attempt to the possibility of heterogeneous cloning. 1999, American scientists cloned the embryo of a rare animal argali from cow eggs. Scientists in China have also cloned early embryos of giant pandas from rabbit eggs, which indicates that cloning technology may become a new way to protect and save endangered animals.
The first cloned cow in China
Chen Dayuan, a researcher at the Institute of Zoology, Chinese Academy of Sciences, said that Weiwei was called the first cloned cow in China because China people did everything from breeding cloned embryos to transplanting cloned embryos in their own country. Last year, Shenzhen and Shandong Laiyang also bred cloned cattle, but their embryos were imported from abroad, not real cloned cattle from China.
It is said that China's embryo production and transplantation technology has been used to successfully breed cloned cattle, which shows that the comprehensive ability of China's cloned embryo engineering technology system has reached the advanced level in the world.
Weiwei is only the pioneer of the first batch of native cloned cattle in China. More than a dozen cloned cows will be born in the next 20 days, which is the largest number of cloned cows in China. Chen Dayuan said: "The cloned embryos of cattle began to be constructed in March last year. After the cloned embryos were implanted into 135 cows in April, 27 cows became pregnant, and the success rate was as high as 20%. There were twins and triplets among the pregnant cows. Later, the cows miscarried, and 12 cows were still pregnant normally. "
The researchers here say that these cloned cattle are cloned from adult bovine somatic cells. The cloned samples were divided into beef cattle and dairy cows, and the somatic cells used for cloning were taken from the ears of two cows. The expected date of delivery of these cloned cattle is concentrated in the second half of this month, and the estimated production figures are 17 to 18.
Cultivating these cloned cattle is a key project funded by the National Natural Science Foundation, which is undertaken by the Institute of Zoology of Chinese Academy of Sciences in cooperation with the Animal Embryo Engineering Center of Zhong Da. It is the first time in China to breed cloned cattle completely with its own engineering technology. The Institute of Zoology, Chinese Academy of Sciences is responsible for the development of bovine cloned embryos, and the Zhong Da Animal Embryo Engineering Center has completed embryo transfer.
Professor Ma Shiyuan of Shandong Academy of Agricultural Sciences, who is in charge of embryo transfer technology, said that the success of cloned cattle experiment is of great significance to animal husbandry, especially beef cattle and dairy cattle industry, and many excellent breeds will be copied in large quantities. He believes that the use of cloning technology can accelerate the improvement process of Chinese animal husbandry varieties more effectively. At present, most of the improved domestic livestock breeds are still bred by hybridization, which is too slow.
Using cloning technology to cultivate high-quality dairy cows and transforming China dairy industry through industrialization has a very broad market prospect. It is reported that the annual output of dairy cows in China is much lower than that in developed countries. In 2000, the per capita milk consumption in China was less than 9 kg, which was far from the consumption of more than 300 kg in developed countries.
The application value of cloned cattle in production is great. The researchers here say that cloned cattle can artificially determine the cattle with the best reproductive quality, and can also control the sex, which alone doubles the economic benefits. The number of cloned embryos of high-quality cattle is almost unlimited, and the production cost is low. At present, it costs about 2500 yuan to import a Holstein cow embryo, but the quality of a cloned Holstein cow embryo is exactly the same as that imported, and the cost is not more than 100 yuan.
Popularization of cloning technology in China
Chen Dayuan, who is also a consultant to the China Giant Panda Breeding Technical Committee, believes that the success of cloned cattle will also provide reference for cloning endangered species. "Cloning technology may become the only hope for endangered species, such as the giant panda in China, to continue their race," he said.
Cloning research in China started earlier. Since 1990s, China has carried out a large number of studies on animal embryonic cell cloning. From 65438 to 0999, the first cloned sheep was born in China. Since then, scientists in China have conducted many cloning experiments in succession.