Goodbye Dolly, as far as future for cloning
EVER since scientists at the Roslin Institute in Edinburgh produced Dolly the sheep in 1997, the impact of cloning on farming has been hotly debated.
Dolly is the worlds first animal cloned from a cell taken from an adult animal. She provoked excitement, but also fear in those who thought doomsday had arrived sooner than they expected.
But Harry Griffin, deputy director at Roslin, says cloning is unlikely to contribute to British agriculture, even in the long term. This is because the benefit is unlikely ever to outweigh the cost.
Instead, research and development is likely to be directed at improving human medicine, such as the production of human therapeutic proteins in the milk of transgenic sheep, cows and goats, he says. Clinical trials of protein, alpha-1-antitrypsin produced from these animals, used to treat cystic fibrosis and emphysema, are already under way.
"But in agriculture, it is hard to see what result of genetic modification through cloning would be of sufficient economic importance to the industry to justify the cost," says Dr Griffin.
Cloning through nuclear transfer could, in principle, allow the creation of an infinite number of clones of the best farm animals. There have already been cloned elite cows sold at auction in the USA for more than £28,000 each.
But these prices reflect the animals novelty value rather than their economic worth, says Dr Griffin. "After all, when you clone an animal, you are only cloning what is the best on that day. Genetic progress through conventional breeding and selection of livestock is relentless, so by the time your clone is born, things will have moved on naturally.
"We do not believe that the creation of a few clones of elite cows will make any significant contribution to genetic progress."
Roslin had some enquiries during the foot-and-mouth outbreak from breeders asking whether animal cells could be frozen and later thawed. "But with the technology costing hundreds of thousands of £s, it really was unfeasible," says Dr Griffin.
Since Dollys birth, scientists around the world have reported cloning of cattle, sheep, mice, goats and pigs. But success rates remain low, with only about 1% of reconstructed embryos leading to live births. Abnormalities, such as large increases in birth weight, have also been noted.
"There are all sorts of experiments under way around the world. One involves introducing genes to alter phytase production in pigs to reduce phosphate excretion. These are called enviro-pigs," says Dr Griffin.
"But it is cheaper and easier to breed plants with lower phosphate levels, or alter phytase levels in the animal feed.
"And it would need to be a brave marketing manager in Europe who tried to introduce genetically modified animals. There is tremendous consumer resistance, as we have already seen with the introduction of GM crops." *
• Not economic in farming.
• Milk proteins research.
• Consumer resistance.
Transgenic – animals containing genetic material artificially transferred from another species, humans in this article.
Nuclear transfer – transfer of cells from an embryo into an unfertilised egg, which has nucleus removed, a method for producing clones.
• Transgenic – animals containing genetic material artificially transferred from another species.
• Nuclear transfer – transfer of cells from an embryo into an unfertilised egg, which has nucleus removed.