AN EXTINCT species could soon be brought back from the dead. Advanced Cell Technology of Worcester, Massachusetts, plans to clone the bucardo, a species of Spanish mountain goat that died out earlier this year.
The company has shown that it can be done by cloning a wild ox called a gaur using the eggs of domestic cows. When 鈥淣oah鈥� is born next month, he will be the first animal ever created by putting the DNA of one species into the eggs of another.
Conservationists warn that the breakthrough should not be an excuse to relax efforts, though. 鈥淎s a last ditch effort for conservation, it might be useful,鈥� says Gordon Reid, director of Chester Zoo. 鈥淏ut it would be daft to imagine that cloning alone could save species,鈥� he adds.
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The Spanish mountain goats will be cloned using tissue samples from the last surviving female, which was killed in January by a falling tree. But all the animals created this way will be female. Chromosomes from closely related species would be needed to create male goats.
The lack of diversity among clones of a single animal could be another problem. 鈥淚f you produce lots of animals that are identical, you get inbreeding,鈥� says Bill Holt of the Zoological Society of London. 鈥淭hey can鈥檛 adapt to stresses, which is what evolution is about and why you need biological diversity.鈥�
To create Noah the gaur, Robert Lanza and his colleagues at Advanced Cell Technology (ACT) employed the same technique used three years ago to create Dolly the sheep. They took 692 skin cells called fibroblasts from a dead guar and fused them with cow eggs stripped of their nucleus. Of the 81 that developed into embryos, 44 were implanted into cows.
Eight foster mothers became pregnant, but five miscarried. Lanza and his colleagues removed three fetuses from two other mothers, and found that they were apparently healthy.
Noah is the only remaining fetus. 鈥淩ight now, all indications via ultrasound are that there are no forseeable problems,鈥� says Philip Damiani of ACT.
There might still be problems, though. 鈥淭here have been reports of high mortality in cloned cows and sheep,鈥� he says. Clones have died hours or days after delivery or had abnormally high birth weights.
However, Noah won鈥檛 be pure gaur. All his mitochondria -cellular organelles that contain their own DNA 鈥� will have come from the cow egg used to create him.
Damiani accepts that cloning won鈥檛 solve everything. 鈥淥ur objective was to prove it could be applied to endangered species,鈥� he says. He envisages 鈥渇rozen zoos鈥� holding tissue from many members of endangered species, such as the giant panda. If numbers fell dangerously low, these tissue banks could be used to increase genetic diversity.
Journal reference: Cloning (vol 2, p 79)