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CLONING OF TASMANIAN TIGER
The largest predatory marsupial at the time of European settlement and once existed on the mainland of Australia until as recent as 4500 years ago. Today the Thylacine is extinct but not in the minds of those who claim to have seen one in the remote bush of Tasmania. Each year there are a number of sightings that are regarded by Parks and Wildlife officers as being probable. It resembles a wolf with the stripes on the lower back giving it the name of tiger. The Tasmanian Tiger has wide and gaping jaws and the last known specimin died in the Hobart Zoo in 1936. A bounty on the Tiger from as early as 1830 led to its extinction due to being regarded as a threat to the sheep farming by the Van Diemen's Land Company.
Extinct Tasmanian tiger one step closer to cloning
Wednesday, May 29, 2002
By Michael Perry, Reuters
SYDNEY ÃƒÂ¢Ã¢â€šÂ¬Ã¢â‚¬Â Australian scientists announced on Tuesday a breakthrough in efforts to clone the extinct Tasmanian tiger, saying they had replicated some of the animal's genes using DNA extracted from preserved male and female pups.
The scientists from the Australian Museum in Sydney said they hoped to clone a Tasmanian tiger in 10 years if they were successful in constructing large quantities of all the genes of the Tasmanian tiger and sequencing sections of the genome to create a genetic library of Tasmanian tiger DNA.
"We are now further ahead than any other project that has attempted anything remotely similar using extinct DNA," Mike Archer, director of the Australian Museum, told a news conference. "What was once nothing more than an impossible dream has just taken another giant step closer to becoming a biological reality," he said, adding that the ultimate aim was to clone a viable reproducing population of Tasmanian tigers.
The Tasmanian tiger (thylacine) was a doglike carnivorous marsupial with stripes on its back that lived on the southern Australian island state of Tasmania. The creature originally roamed Australia and Papua New Guinea, but sometime between 2,000 and 200 years ago disappeared from the Australian mainland, only to be found in Tasmania.
It took humans only some 70 years to make the Tasmanian tiger extinct, as farmers in the 1800s began shooting, poisoning, gassing, and trapping the animal, blaming it for attacking sheep. The last known Tasmanian tiger died in 1936, and it was officially declared extinct in 1986.
COMPLEX OF GUILT
The project to bring the Tasmanian tiger back from extinction began in 1999 when Australian Museum scientists extracted DNA from an ethanol-preserved female pup in its collection.
In 2001, further DNA was extracted from two other preserved pups; the tissue source for this DNA was bone, tooth, bone marrow, and dried muscle. Archer said the alcohol-preserved female pup's DNA had given scientists the Tasmanian tiger's X chromosome and the other samples the male Y chromosome.
In May 2002 the museum's scientists, using the extracted DNA, replicated some of the Tasmanian tiger's genes using a process called PCR (polymerase chain reaction).
"The supposedly dead DNA in fact reacts in the way live DNA does. Clearly the DNA we collected was not extinct; it works," Archer said. "It makes molecule cloning possible."
Archer said if the museum was successful it would seek to clone a viable population of Tasmanian tigers, using the Tasmanian devil, another carnivorous marsupial, as a host. "We want a viable population. We don't want a strange animal pacing back and forth in a laboratory. What we want to do is put that animal back in the wild and for that we need a viable, reproducing population," he said.
But Archer said the technology for the final stage of cloning, putting the Tasmanian tiger's genetic material into a Tasmanian devil host cell which has been stripped of the devil's genetic material was still to be developed. "We don't know the length of this journey. Its up to the speed with which technology keeps pace with the vision. But I am optimistic," he said.
"The Tasmanian tiger is an iconic Australian animal. Its woven in a complex web of guilt because Australians made it extinct. We need to lift this burden of guilt."