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'Sister Clones' Of Dolly The Sheep Have Aged Like Any Other Sheep, Study Says (npr.org)
An anonymous reader quotes a report from NPR: About four years ago, Kevin Sinclair inherited an army of clones. "Daisy, Debbie, Denise and Diana," says Sinclair, a developmental biologist at the University of Nottingham in England. "'Sister clones' probably best describes them," Sinclair says. "They actually come from the exactly the same batch of cells that Dolly came from." In an article out Tuesday in the journal Nature Communications, Sinclair and his colleagues write that the ewes' age, along with their strapping health, might be a reason for people to start feeling more optimistic about what cloning can do. Dolly's life did not turn out as scientists in the cloning field hoped it would. She died young -- 6 1/2 -- with a nasty lung virus. "That was really just bad luck," Sinclair says, and had "nothing to do" with the fact that Dolly was a clone. It was a daunting concept for those in the cloning field, because, says Sinclair, "If you're going to create these animals, they should be normal in every respect. They should be just as healthy as any other animal that's conceived naturally. If that is not the case, then it raises serious ethical and welfare concerns about creating these animals in the first place." But, the good health of the 13 clones in the Nottingham herd suggest better prospects for the procedure. Sinclair and his colleagues evaluated the animals' blood pressure, metabolism, heart function, muscles and joints, looking for signs of premature aging. They even fattened them up (since obesity is a risk factor for metabolic problems including diabetes) and gave them the standard tests to gauge how their bodies would handle glucose and insulin. The results? Normal, normal, normal. "There is nothing to suggest that these animals were anything other than perfectly normal," says Sinclair. They had slight signs of arthritis (Debbie in particular), but not enough to cause problems. "If I put them in with a bunch of other sheep, you would never be able to identify them," he says.
What premature aging? Dolly died of a cancer caused by a particular virus, a disease that is relatively common in sheep. Extensive efforts to look for signs of premature aging found nothing (although that didn't stop some superficial media coverage from speculating otherwise).
As far as why, with livestock at least, farmers want to make copies of productive animals, where genetics is a huge factor. At the moment, an animal that wins the genetic lottery (although a lot of effort goes into picking parents to make this easier) ends up becoming a very expensive breeder, and animals used for actual production are one or two generations separated. Cloning could potentially cut out the extra generations and be cheaper.
Cheaper, yes, but there's a bit of risk. Genetically identical animals are all susceptible to the same diseases and environmental conditions. A virus that would have wiped out 5% of the herd before could now wipe out the entire herd, because the entire herd is equally susceptible to it. Combine this with globalization and the entire world could be suddenly out of sheep.
This has actually happened before with the "Gros Michel" banana cultivar that was all but wiped out by the Panama disease. The modern cultivar, Cavendish, has the same risks and will likely become unviable in the future due to disease. Hopefully we'll have another cultivar lined up by then.
This is ewegenics!
My ism, it's full of beliefs.