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Cloned Cows More Youthful Than Dolly the Sheep LOS ANGELES (AFP) - US researchers who produced six healthy cows through cloning found cells taken from the cows showed rejuvenation that was the reverse of the premature aging reported in the case of Dolly the cloned sheep. Dolly, cloned in 1997 by British scientist Ian Wilmut, was old before her time as her cells appeared to inherit the age of her genetic mother. However, "Chromosomes from the cow sisters are the picture of youth," according to Advanced Cell Technologies (ACT) researcher Robert Lanza, in the report published in Science magazine. "Surprisingly ... the cloning process seemed to restore the 'nine lives' of these cells in the six cows," Lanza, a co-author of the research, said. "Cells from the cow clones appear to have recaptured and even prolonged their youth," Lanza explained. "Instead of being zero to four division cycles away from the end of their lives, cells taken from the cows were more than 90 cycles away from the end." The ACT researchers based in Worcester, Massachusetts used cells that were near the end of their lifespan, instead of cloning from cells that had been starved and sent into a resting state - like those used for cloning Dolly. While they do not understand yet why there should be such a marked contrast in the youthfulness of the cloned animals, the condition of the donor cell appeared to be significant, researchers say. And the different origins of the cells could be a factor, the report noted. Mammary cells were used for Dolly and fibroblast (connective tissue) cells for the cows. Researchers hope that cloning could supply a crop of youthful cells for uses from design and transplant of replacement tissue for the human body, to increasing breeding years of farm animals. Another indication of aging in cells is in the wear and tear on the telomeres - the regions at the tip of the chromosomes that stop the genetic thread from fraying as the cell divides, according to the researchers. In the cells taken from the cloned cows, the telomeres were actually longer - that is, younger-seeming - than those from normal cows of the same age, and in most cases even longer than those of new-born cows. Lanza and his co-authors do not yet know if the findings translate into a longer lifespan for the animals themselves. "Despite these unsolved mysteries, the finding erases a lingering doubt about the utility of cloned cells, by demonstrating that the process does not automatically rob cells of a normal lifespan," Lanza added
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