DNA BREAKTHROUGH: EXTINCT ANIMALS TO MAKE A COMEBACK

* Scientists partially map woolly mammoth DNA
* Mammoths and elephants almost identical
* It is possible to "rebirth" extinct creatures

RESEARCHERS have sequenced the gene map of a long-extinct, mummified woolly mammoth, using DNA taken from its hair.

The sequence shows that mammoths were more closely related to modern, living elephants than previously thought, and they found some elements, such as evidence of inbreeding, that may shed light on why the giant creatures went extinct, the researchers reported today.

And it shows that it is possible to reconstruct the genomes of extinct creatures, they reported in the journal Nature.

"By deciphering this genome we could, in theory, generate data that one day may help other researchers to bring the woolly mammoth back to life by inserting the uniquely mammoth DNA sequences into the genome of the modern-day elephant,& quot; Stephan Schuster of Pennsylvania State University, who helped lead the research, said in a statement.

"This would allow scientists to retrieve the genetic information that was believed to have been lost when the mammoth died out, as well as to bring back an extinct species that modern humans have missed meeting by only a few thousand years."

The team notched up a first breakthrough last year by using mammoth hair to extract mitochondrial DNA, genetic material that is inherited from the female line.

The latest work focuses on nuclear DNA, or chromosome-bearing strands that have the most important protein-making software.

"We're sequencing random fragments and believe we have 50 per cent of the genome. We don't yet know the full size of the genome," co-author Webb Miller said.

CRACKING THE CODE

The hair technique marks a giant's step forward compared to the previous method, which consisted of teasing DNA out from bone marrow in the remains of frozen marrow.

DNA of this kind can be badly damaged by bouts of freeze-thaw over the millennia, enabling water and bacteria to enter through porous bones.

But the keratin sheath of hair provided a surprisingly good shield for the DNA inside, said Miller.

The two mammoths from which the hair shafts were taken died around 20,000 years and 50,000 years ago respectively.

In addition to the new source for gene sequencing, the scientists have harnessed new technology that can unravel DNA code in a fraction of the time it took a few years ago.

Rebuilding the mammoth's genetic code has fired speculation that scientists may one day revive this species and other Ice Age beasts on the lines of the Hollywood movie Jurassic Park.

These creatures became extinct relatively recently, offering the possibility of recovering scraps of DNA from bodies that have been preserved in bitter sub-freezing chill.

Miller said it should one day be theoretically possible to replicate a mammoth - or rather, a mammoth-like animal - by taking the elephant's genome, stripping out the code that is specific to the elephant and replace it with code specific to the mammoth.

The new code would be fused into an elephant's egg, replacing its programming nucleus, and then be transplanted into a female elephant.

But, he said, such an endeavour was fraught with technical hurdles and would need lots of money.

The sequence shows that mammoths, which died out around 10,000 years ago, evolved slowly.

"We discovered that individual woolly mammoths were so genetically similar to one another that they may have been especially susceptible to being wiped out by a disease, by a change in the climate, or by humans," said Schuster.

The researchers will have to analyse the DNA to pinpoint some of the precise sequences unique to mammoths, but have some hints.

"Our data suggest that mammoths and modern-day elephants separated around six million years ago, about the same time that humans and chimpanzees separated," added Penn State biologist Webb Miller, who directed the study.

CLOSE RELATIVES

Miller said the findings can help scientists understand evolution.

Important gaps in the picture remain, but even so, enough data is there to make a comparison between the woolly mammoth (Mammuthus primigenius) and its closest living relative, the elephant, they said.

The two species are so similar that their DNA differs by just 0.6 per cent, or about half the differences between humans and chimps.

The researchers have been pulling DNA out of mummified mammoths and their hair for more than a decade, but because it is so old, the DNA is broken down. It is also contaminated by bacteria and fungi.

Mammoths offer a better target than most extinct animals because many of their bodies have been frozen since death - some so thoroughly that the meat is still edible.

The Penn State researchers believe they have about 80 percent of its genome complete.

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Last Edited by Phennommennonn on 10/30/2011 08:01 PM