Shadow over cloning (6.27)

OA show ('918 '); in May 1999, the British journal Nature revealed that Dolly would grow old and die faster than ordinary sheep, which was caused by the limitations of somatic cloning technology Dolly's "biological age" and "birth age" are not consistent Dolly's DNA was taken from a 6-year-old sheep, whose age of birth is 3 years old According to DNA, its biological age should be 9 years old In other words, since we have cloned the gene, we have also cloned the age So it's said that Dolly is an old sheep in a lamb costume A team of scientists from the Roslin Institute in Scotland and ppl medical company in the UK, which bred dolly, analyzed the chromosomes of dolly and the other two cloned sheep bred from embryonic cells, and compared the telomere length with that of the same age ordinary sheep It was found that the average telomere length of the three cloned sheep was shorter than that of the same age ordinary sheep In the three cloned sheep, Dolly's DNA was slightly damaged, and its telomere length was shortened the most, about 20% shorter than that of the same age sheep, which means that Dolly aged faster than the actual age So people doubt the future application value of cloning technology Telomere is the terminal of chromosome, which has the function of keeping expansion The length of telomere will shorten with the cell division According to some theories, telomere may be one of the determinants of cell aging When the telomere of chromosome is short to a certain critical length, the cell will no longer divide and die A calf was cloned from the ear cells of a cow by the biology experts of the National Agricultural Research Institute of France However, the calf suffered from thymus atrophy at birth and died of severe anemia 54 days after birth The anatomy found that its immune system did not develop normally In 1998, experts cloned another calf with similar technology, and the result was the same disease Because the method of cloning these two calves is almost the same as that of cloning Dolly, experts also question the reliability of cloning technology Source: Sichuan Animal Husbandry and veterinary medicine 2000.5 China feed industry information network gnz (author:)