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Saturday, December 6, 2008

Scientist complete first step in the Cloning of a Woolly Mammoth

On Nov. 19, scientists from Penn State University announced that they had succeeded in piecing together the majority of the woolly mammoth's genome, bringing the world one step closer to the Jurassic Park fantasy of using recovered DNA to bring an extinct species back to a shaggy, lumbering existence.

The wonders of eBay allowed the scientists to purchase a $130 bag of 20,000-year-old woolly-mammoth hair from a vendor in Moscow, and the wonders of science allowed them to extract the mammoth's genetic information in the most successful attempt to date to sequence an extinct animal's DNA. DNA in general breaks down after 60,000 years or so, making the possibility of a real Jurassic Park scenario — complete with flying pterodons and bloodthirsty tyrannosaurs — remote. Still, scientists see the completion of the genome as the first step to uncovering and understanding the reasons behind the mammoths' extinction, and the effort has brought the cloning question back to the public's mind in a (ahem) mammoth way.

Though Dolly the sheep was the first clone to be shoved into the limelight, in 1996, the process of human-directed cloning has existed since 1952. In that year, American researchers Robert Briggs and Thomas King successfully removed the nucleus of a tadpole's embryonic cell and transferred it to a donor cell, cloning 27 tadpoles in the experiment. This groundbreaking achievement landed the scientists the internationally lauded Charles Leopold Mayer Prize of the Académie des Sciences, making them the first Americans in history to receive the award.

Since Briggs and King's discovery, a veritable Noah's Ark of clones has been created, ranging from fish in 1963 to horses in 2003. Dolly's birth, at the Roslin Institute in Scotland, marked the first successful cloning of a mammal from an adult cell, proving that a complete animal could be grown from the DNA contained in cells from just about any part of another.

Attempts at cloning haven't stopped at the nonhuman animal kingdom: scientists have long speculated about cloning humans as well, but for the most part, ethical considerations have prevented any such notions from being put into practice. President George W. Bush urged Congress to enact legislation banning human cloning in 2002 after being "deeply troubled" by rumors that a Canada-based UFO cult had announced the birth of a successfully cloned baby girl. Though the claims were never substantiated, Congress passed the Human Cloning Prohibition Act in 2003. Congresswoman Sue Myrick, who supported the act, claimed that "anything other than a ban would license the most ghoulish and dangerous enterprise in human history." Religious groups also came out in force against human cloning; science was threatening to disrupt the natural order of life, they said, and researchers "playing God" were treading on dangerous existential territory. A representative of the U.S. Conference of Catholic Bishops hailed the passing of the bill, stating, "This vote reflects America's rejection of the notion that human life is a commodity to be created for experimentation."

Cloning has generated controversy outside of ethics questions as well — or at least, outside of these particular ethics questions. In 2004, South Korean researcher Hwang Woo Suk shot to fame after claims that his team had successfully extracted potentially disease-curing stem cells from a cloned human embryo. However, mere months later, Hwang's reputation dissolved after a Seoul National University panel concluded that much of his research was "intentionally fabricated." Hwang was accused of doctoring pictures of his supposed patient-specific stem-cell lines and was forced to resign. Though the controversy stunned South Korea, the nation resumed its cloning research, and in 2008 it unveiled seven Labrador retrievers, cloned from a drug-sniffing canine, that shared her superior narcotic-detecting abilities.

The genetic sequencing of the woolly mammoth, meanwhile, raises the similarly fraught but increasingly realistic possibility of cloning extinct animals, a process that Jurassic Park director Steven Spielberg has called "the science of eventuality." Still, scientist Stephan Schuster, who led the team at Penn State, isn't holding his breath. "What I'm trying to say is that there is a workable route to do that, but it is at this time technically, and cost-wise and time-wise, not feasible."


Scientists on Wednesday revealed they had unravelled much of the genetic code of a woolly mammoth, in what could be the first baby step in bringing the extinct creature, or at least characteristics of it, back to life.

Researchers from the U.S. and Russia, in a million-dollar project, said Wednesday they have sequenced more than three billion DNA bases of the mammoth nuclear genome, obtained from ancient hair shafts extracted from two specimens dating back roughly 20,000 years. That represents roughly 80 per cent of the 4.17 billion DNA pairs they expect to find in the mammoth genome, assuming the mammoth genome is similar in size to that of modern African savanna elephants.

Stephan Schuster, a Penn State University biochemistry professor and co-author of the new research, said the early findings suggest it's only a matter of time before the complete sequence is obtained, raising the possibility that an extinct species could be brought back based on its genetic material. "It could be done. The question is, just because we might be able to do it one day, should we do it?" said Schuster. "I would be surprised to see if it would take more than 10 or 20 years to do it."

The research, which also found that woolly mammoths split into two genetic groups about two million years ago, will be published in the Thursday edition of the journal Nature. Hamilton, Ont.-based University of McMaster anthropology Prof. Hendrik Poinar wasn't part of the Nature study but has done pioneering work extracting nuclear DNA from bone in woolly mammoths. He said the research marks the beginning efforts in the quest to complete the mammoth genome, but cautions that it is only a beginning step.

"With sequencing of this sort, you want to get about eight to 12-fold coverage of the genome, so you can be reasonably sure of its accuracy," he told CBC News. "Here we are talking about a 10th of that coverage, so there's a large amount of room for error, but it's great as a proof of principle." Fossil samples of bone and hair have already provided researchers with access to DNA from extinct animals. While bone and hair samples are more known as a resource for the more abundant mitochondrial DNA, the more revealing nuclear DNA can be found in the samples as well.

The issue with ancient samples is contamination: DNA from bacteria and other foreign life forms can mix with samples and degrade them. Schuster's group found a way around this by focusing on hair, which they found was easier to decontaminate. The method used by the researchers isn't likely to be applicable to older creatures like dinosaurs, however, because whether the DNA can survive the rigours of thousands of years depends in large part on how undisturbed the specimen is by the ravages of its environment, Poinar said.

While the relatively unchanging permafrost of Siberia is capable of preserving specimens as old as 100,000 years, the time of dinosaurs was much warmer and the land mass they lived on was closer to the equator, unsuitable conditions for permafrost. That means we won't be seeing Jurassic Park any time soon, said Poinar. As for resurrecting a woolly mammoth, he said that while it's admittedly a fascinating idea, it's years away from reality because of all of the intermediary steps that would need to be taken. "You would need to find a way to synthesize a full set of chromosomes from the genome data and right now we don't even know how many chromosomes it had," he said. "If you could do that, you could, in theory, take the chromosomes of an Indian elephant and alter them to those of a mammoth and then plant those chromosomes in an egg; you could then bring it to term," he said. "But we need that chromosome information — right now we have no scaffold to build on," said Poinar. It might be possible, however, to isolate ways in which the mammoth genome differs from modern-day elephants and possibly isolate a particular feature, according to an accompanying article in Nature. Svante Paabo, 53, of the Max Planke Institute for Evolutionary Anthropology in Leipzig, Germany, told the scientific journal such a creation represents the closest the public might come to seeing a mammoth in his lifetime.

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