French scoff at bid to clone
Tassie tiger
ABC ONLINE 1/06/2002
French geneticists have dismissed as meaningless
claims by Australian scientists that they have cleared a major hurdle for cloning the
extinct Tasmanian tiger.
The Australian Museum in Sydney announced this week it had replicated DNA from a preserved
specimen of the Tasmanian Tiger, which was declared extinct in 1936.
The museum says a living DNA library of the creature can now be constructed and, in
theory, it could be brought back to life within 10 years.
But Genpole, a campus of more than 20 biotech labs situated south of Paris, says all the
Australians have done is "copy fragments of DNA" under a long-standing method
called polymerase chain reaction (PCR).
"This technique has been widely used for some 20 years to reproduce DNA fragments in
order to analyse or sequence then," Genpole said in a press statement.
Cloning, it noted, entails replicating the entire genome of an animal.
The usual method is to remove the core, or nucleus, of an egg and replace it with genetic
material from the creature that is to be cloned, and then put the egg in a uterus.
The technique has been used on numerous farm animals, although the success rate remains
low.
"In the case of the Tasmanian tiger, the researchers only have dead cells that have
been perserved in alcohol, and whose nuclei are therefore inert, non-functioning and
totally unusable," Genpole said.
"Ethanol (laboratory alcohol) may preserve DNA well, but it still irreversibly
destroys numerous other structures that are needed for the nucleus to function
properly."
It added: "There are no grounds for thinking that one day it will be possible to
reproduce a creature as complex as the Tasmanian tiger by introducing DNA fragments,
however numerous and complex they may be, in a denucleated egg.
"The 'cloning' of the Tasmanian tiger has no meaning for a very long time to
come."
The Tasmanian tiger, scientifically known as the thylacine, was the largest known
carnivore marsupial (a creature with a pouch to carry its young) until it was pronounced
extinct in 1936 after decades of being hunted as vermin.
The Australian Museum's replicated DNA comes from tissue from a 130-year-old thylacine
female pup specimen preserved in ethanol.
Two other high-quality tissue sources, including bone, tooth and dried muscle from male
specimens, were also found in the museum's collection.
END OF REPORT
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