World's Purest Inbreed-line Pig DevelopedInbreeding among human beings is generally acknowledged as detrimental to the successful generation of positive genetic factors. However, the inbreeding of pigs has been found to be a successful way of developing pig organs suitable for transplanting into human beings.Scientists in southwest China's Yunnan Province have successfully developed pigs born of a sow mated with its own son or parents, in the same brood, for 18 successive generations. The number of these inbreed-line pigs has increased to over 400, which were divided into 18 sub-lines, since the experiment began in a remote village of Yunnan Province in 1980, said Zeng Yangzhi, a research fellow in charge of the project. No ill effects from the inbreeding have been recorded in the inbreed-line pigs. The survival rate of the 17th inbreeding generation, developed last year, exceeded 80 percent, and no pigs had deformities, compared with a three percent survival rate in the early stage of the experiment, he added. Reproduction of two more generations on this basis has marked the birth of the world's purest pig, that is to say, 98 percent of their chromosome are identical. The resulting animals are scientifically called a highly homogeneous pig species "This is an unparalleled result of full-sibbling inbreeding," said D. Morgen, a professor at South Dakota State University, after studying the experiment in Yunnan. D. Morgen has been engaged in rat and chicken inbreeding research for many years. There is no record of the inbreeding of large mammal for more than 10 successive generations in elsewhere of the world, according to the Information Research Institute of the Chinese Academy of Medical Sciences. The United States and Britain experimented with the inbreeded-line of 200 pigs, but they had to give up half way because of poor results, or academically inbreeding-depression. The success of the Chinese biologists lies in their formulation of a workable plan and persistence in choosing the beneficial genes and eliminating the harmful ones in each generation, Zeng said. Zeng Yitao, a life sciences academician, said, "Cultivation of inbreed-line pigs provides a huge amount of donor organs with clear genetic backgrounds for transplanting between different species, namely, into humans, the only near-term solution for solving the worldwide chronic organ shortage." As pigs are similar to humans in terms of organ location in the body, physiological variation, and metabolism, and scientists around the world are transplanting modified pig organs into humans. Britain's PPL Therapeutics, the company that gave the world Dolly the cloned sheep, developed the world's first cloned pigs, potentially heralding a breakthrough in animal-to-human organ transplants. A nine-member group of genetic engineering experts said that the inbreed-line pigs are superior to cloned pigs because cloned pigs are merely a replica of a specific cell, and organ transplants using cloned pigs are subject to harmful gene reactions. "But the inbreed-line pigs can be likened to a precision instrument in physics research or pure reagents in chemical reactions. They serve as highly sensitive and reproductive donor material," said one expert. Inbreed-line pigs are also ideal donor animals for testing new drugs to ensure product safety. Overseas medical experts predict that animal-to-human technology will take an enormous leap forward in the next five years. China plans to have mass reproduction of inbred-line pigs and intends to market them next year. An industrial firm in one coastal area recently signed a 23- million-yuan contract to reproduce inbreed pigs. |
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