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Chinese Experts Report Breakthrough in Calve Cloning
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2002-03-11
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| A group of Chinese scientists on Thursday announced their success in cloning calves from adult cells, a technique similar to that used to produce Dolly the sheep in Britain four years ago. Five calves are alive and in good health, even though nine other clones have died since they were born early this year, said Chen Dayuan, who led the research supported by the Chinese Academy of Sciences (CAS). The results made China the fourth country, following Japan, New Zealand and the United States, to obtain techniques to create cattle by non-sexual methods, said Chen, a research fellow with the CAS Institute of Zoology. All the calves were cloned of a finely-bred bull and a high-performing dairy cow. They were produced by using somatic cell nuclear transfer, the process that produced Dolly the sheep, the world's first cloned animal, in which an adult cell was fused with an egg. The researchers took cells from the ears of the bull and the cow, combined the cells with oocytes of the surrogate mother, then implanted the cloned embryos into the cattle to make them pregnant. Twelve surrogate cows gave birth to 14 calves between January 18 and February 11 this year in Zhongda Animal Embryo Engineering Center in east China's Shandong Province. The calves are all genetically identical to the two karyon providers, said Chen. The surviving dairy cows are distinguishable by their black and white markings. Chen acknowledged that they still need to deal with a lot of problems, including low rates of pregnancy and survival, and a high rate of miscarriage, before the technology is eventually used in commercial production. A total of 980 eggs were cultivated, 261 of which developed into blastula, the early developmental stage of an animal. Only 26 of 112 cattle became pregnant after 230 blastulas were implanted into their wombs, and 12 finally gave birth. Still, some great progress has been made through the research, such as shortening the maturity period of the oocytes, according to a scientist panel organized by China's Natural Science Foundation to review the research. "The breakthrough in cattle cloning from adult cells is of great significance to life science and biotechnology in China," said geneticist Chen Zhu, a CAS academician. Embryologist Tong Dizhou initiated China's first research of cloning on fish in the 1960s. Chinese scientists have speeded up the research in cloning technology since the landmark Dolly, the sheep, was born in 1997 in Britain, hoping future techniques may benefit the country's underdeveloped stockbreeding industry. Dairy production is believed to have huge potential in China since milk consumption among China's 1.3 billion people is only 10 percent of the average in some Western countries. The new technology will help breed cattle for higher-grade beef, greater milk production, and medical purposes. China will continue to increase its research and development efforts in the field of life science in order to catch up the most advanced technology in the world, said CAS President Lu Yongxiang. |
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