Scientists hoping to clone prehistoric woolly mammoths are preparing their first frozen DNA samples in a bid to revive the species.
The specimens of bone marrow, muscle and skin were unearthed last August in the Siberian tundra where they had been preserved in ice for thousands of years.
Researchers at the Gifu Science and Technology Centre and Kinki University want to use the genetic material in the cells to clone a woolly mammoth, according to Akira Irytani, a scientist at Kinki University in western Japan.
First they must determine whether the five specimens airlifted from Russia are really from mammoths. If so, they must decide whether the DNA locked inside is well enough preserved to self-replicate. After that, it could take several years to actually produce an animal. "There are many different problems to overcome," the Gifu Centre's Hideyoshi Ichibashi said. "I think we can move ahead only one step at a time."
The idea of cloning mammoths from specimens discovered in permafrost holds a perennial fascination for scientists since cloning of adult mammals was shown to be feasible with Dolly the sheep in 1996. But in 1999 Alexei Tikhonov, chairman of the Mammoth Committee of the Russian Academy of Science, who took part in an expedition that uncovered one of the animals buried in the permafrost, said he and his colleagues on the scientific committee were not preparing to clone the mammal. "You have to have a living cell for cloning, and not a single cell can survive in the permafrost," he said then.
Dr Irytani said the idea was to develop the cloning technology on extinct animals to aid in the preservation of endangered species. So far, six mammoths have been discovered and partially or completely unearthed from the permafrost, which is as hard as concrete and has to be broken up with jackhammers.
Kinki University scientists, with veterinary experts from Kagoshima University in southern Japan, have searched for mammoth DNA samples since 1997 in Siberia. The techniques used include ground-penetrating radar, which can detect the size and shape of buried objects.
So far, no cells bearing cloning-quality DNA have been found. The initial plan called for finding mammoth sperm cells, which could be used to inseminate a modern day elephant and create a mammoth-elephant hybrid. But no sperm cells have been found, and other samples retrieved during previous excavations, including legs buried under permafrost, have turned out to be left unusable by time and climate changes.
Dr Irytani was more hopeful about their samples, estimated at 20,000 years old, saying they had been well preserved in the ground at about -20C (-4F).
Mammoths died out about 13,000 years ago because humans hunted them to extinction. One plan to revive mammoths would not use cloning, but the more straightforward technique of artificial insemination of any intact sperm into African elephants, the mammoths' closest living relative.