November 19, 2008

Scientist Map DNA Of Ice Age Wooly Mammoth

Scientists are making remarkable strides in unraveling much of the genetic code of the ice age's wooly mammoth.

The million-dollar project is an initial rough draft, detailing the mammoth's more than 3 billion DNA building blocks.

The groundbreaking work even has some considering a future where certain extinct, prehistoric species might one day be resurrected.

"It could be done. The question is, just because we might be able to do it one day, should we do it?" said Penn State biochemistry professor Stephan Schuster, co-author of the new research.

"I would be surprised to see if it would take more than 10 or 20 years to do it," he told the Associated Press.

The project is about 80 percent complete, enough to give scientists new clues on the timing of evolution and the lethal details of extinction.

The scientists are using mammoth hair, instead of bone, found frozen in the Siberian permafrost, providing biologists a new method to study ancient DNA.  Schuster likened the work to "CSI Siberia".  

The technique, combined with improvements in genome sequencing and the nascent field of synthetic biology, has scientists envisioning a science-fiction-like future.  Crucial to the mammoth mapping are about 20 hairballs.

Previous work to sequence ancient DNA were hindered because bacteria, viruses and parasites often crept into the bone fossils during the long degradation process, making much of the genetic material something other than what scientists actually study.

For instance, current work on Neanderthal DNA has been hampered because only about 6 percent of the recovered genetic material actually belonged to the ancient species.

It should be possible to someday recreate any extinct creature "within the last 100,000 years", Schuster says, as long as it was trapped in permafrost and had hair.  However, that excludes the Jurassic Period, the time of dinosaurs.  In other words, any real-life sequel to extinction would likely be Ice Age 3 than Jurassic Park IV.

Japanese scientists said three years ago that they planned to use frozen mammoth sperm to impregnate an elephant, and raise the resulting offspring in a Siberian safari park.  However, Schuster said using genetics to engineer a mammoth is more practical.

Hendrik Poinar, an anthropology professor at McMaster University in Hamilton, Ontario, no longer considers such ideas impossible.

Poinar, who was not involved in the current study but did consult on the Jurassic Park film, said director Steven Spielberg may have been right when he said: "This is the science of eventuality."

George Church, director of computational genomics at Harvard Medical School who was not involved in the study, said it doesn't have to be a fully resurrected mammoth. Instead, scientists might examine what makes the mammoth different from its closest cousin, the African elephant, and create a hybrid with hair that would live in a zoo.

"People would like to see a hairy elephant," he told the AP.

Alex Greenwood, a biology professor at Old Dominion University who studies ancient DNA, said the work is "an amazing achievement."

On the more practical side, the new research will better distinguish the evolutionary differences between mammoths and elephants and ultimately humans and chimps, according to Church.

Elephants and mammoths are of comparable size, with both standing roughly 8 to 14 feet tall.  However, the two species diverged along evolutionary paths about 6 million years ago, at about same time humans and chimps did, said Schuster.

Nevertheless, there are twice as many differences between the genetic makeup of humans and chimps as there are between mammoths and elephants.

"Primates evolved twice as fast as elephants," said Schuster.

But some animals, such as rodents, have undergone even more evolutionary changes, indicating that the phenomenon might be more a factor of size or metabolism, said the study's co-author Webb Miller. 

Interestingly, the scientists also found that in the roughly 50 species with mostly mapped genomes, there are certain areas where the genetic code is exactly the same in all the animals except the mammoth.

Miller explained that in other animals these proteins "stayed the same for a very long time except in the woolly mammoth".

"I don't know what it means. All I did was find them," said Miller, a biology and computer science professor at Penn State.

Miller and Schuster observed that most of the mammoths they studied had far less genetic diversity than other species that are still alive, something that may serve to provide clues about the biology of extinction.

The scientists are applying their newfound knowledge toward efforts to save the endangered Tasmanian devil of Australia. Schuster said the duo found the same lack of genetic diversity in the modern day animal.

The study was published in Thursday's journal Nature.


Image 1: Ball of permafrost-preserved mammoth hair containing thick outer-coat and thin under-coat hairs. (Stephan Schuster lab, Penn State)

Image 2: Penn State University genomicists Webb Miller and Stephan C. Schuster, in front of the Roche / 454 Life Sciences' Genome Sequencer 20 System that was used to sequence mammoth DNA. (Lynn Tomsho, Penn State)

Image 3: Drawing of a wooly mammoth.


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