The Japan Times, January 4, 1998
By TIM JOHNSON
Scientist planning to resurrect woolly mammoth is not joking
Scientist Kazufumi Goto is keeping his fingers crossed, hoping that one day his telephone will ring with word that searchers have at long last turned up a woolly mammoth entombed in the frozen tundra of Siberia.
But not just any old woolly mammoth remains will make the grade for the intrepid veterinary scientist at Kagoshima University. He seeks a well preserved specimen that is anatomically intact and reproductively viable.
Goto, 47, gets straight to the point: "Our main interest is frozen mammoth sperm. And I'm hoping that some day we will get the material we need."
Obtaining the woolly mammoth's male essence would allow Goto to set in motion his ambitious plans to resurrect the Ice Age pachyderm which mysteriously disappeared from the Earth around 10,000 years ago.
"Honestly, it won't be easy," Goto is quick to acknowledge. "But we believe in the possibility and will keep trying because no other scientist can deny our theory."
The ancient sperm, if its DNA remains intact, would be used to inseminate an egg cell of a female elephant. The egg would be implanted into an elephant's womb to be carried to full term.
If a female half-mammoth, half-elephant is born and reaches maturity, its egg cells would be collected and fertilized with 100 percent mammoth sperm to create a purer hybrid mammoth.
Over successive generations of impregnating female hybrids, a hairy beast increasingly close genetically to the original woolly mammoth, which stood around 3 meters tall, could be created Goto says.
Some skeptics suggest Goto is operating in the realm of science fiction.
The inevitable comparisons have been made with the HolIywood blockbuster movie "Jurassic Park," in which dinosaurs are given a new lease on life by being cloned from reconstructed DNA extracted from dinosaur blood taken from prehistoric mosquitoes preserved in amber.
But Goto insists that his theory has a sound scientific basis.
In 1990, Goto and his associates succeeded in using killed bovine sperm cells to impregnate a cow, which successfully gave birth to a healthy calf. The bovine sperm had been repeatedly frozen and thawed over several months before being injected into a bovine egg cell.
"That meant that the sperm does not necessarily have to be alive so long as the sperm DNA is intact," he says.
The reverse is not true, however, as an egg cell killed by freezing and thawing never yields a viable fertilized egg by injection with viable or killed sperm, according. to Goto.
He stresses that his project does not amount to cloning which involves manipulation of DNA of an animal cell so that the cell grows into a genetic duplicate of that animal.
In any case, most ancient cells would be too severely degraded from repeated freezing and thawing to be of any use in cloning.
Sperm cells, by contrast are "very, very tough" in terms of their ability to withstand environmental stress, though their incomplete DNA makes them unsuitable for cloning.
"The main point we are interested in is whether sperm DNA remains intact after more than 10,000 years," Goto says.
He considers it significant that British scientists have successfully produced hybrid calves from Asian and African elephants.
"That's why I think we may have a chance to get a hybrid between a mammoth and an Asian elephant," he says, citing Japanese geneticist Tomoo Ozawa's discovery that the Asian elephant may be genetically closer to the mammoth than it is to the African elephant.
Mammoths are believed to have more chromosomes than elephants, but horses and donkeys can produce offspring even though horses have 64 chromosomes and donkeys have only 62.
Goto, who has been busy fielding inquiries from the international media and from other scientists hoping to become involved in the project, says that finding the raw material needed to re-create the mammoth poses the most immediate challenge.
In September, he and a team of Japanese, British and Russian sperm hunters excavated cliffs overlooking the Kolyma River in the northeastern Siberian republic of Sakha for the second year in a row, but they failed to find any frozen mammoth sperm.
A third effort is planned for this summer at the same site.
Goto says he is undaunted that there have been only three officially reported finds of frozen whole-body woolly mammoths in Siberia in the last 100 years.
"There are more frozen mammoth discoveries than officially reported," he insists, suggesting that those who find them are apt to keep silent and enrich themselves by selling the tusks for ivory.
While the project to bring back the prehistoric beasts has kindled the imaginations of many and even spawned a small-scale industry in Japan involving the sale of woolly mammoth T-shirts, toys and the like, Goto says he would be happy enough to find frozen sperm from less high-profile creatures like extinct deer, horses and cattle so long as there exist related species to pair them.
He asserts the project is not without scientific merit.
It would contribute essential knowledge to global efforts to preserve cells of various rare and wild animals in "frozen zoos" for the purpose of conserving species diversity, he says.
"We don't know the future of those cells — how long DNA will be intact," Goto says. "So if we examine the state of frozen-preserved cells of ancient animals, this knowledge will help predict the fate of cells we started to preserve by freezing and improve the method of preservation."
Also, he says, comparing mammoth and elephant genes may help clear up the mystery of why mammoths are extinct and elephants are not.