Posted on 05/28/2002 7:23:33 PM PDT by Pokey78
Australian team has copied parts of DNA but faces huge odds
A team of Australian scientists pledged yesterday to salve their country's conscience by bringing a cloned Tasmanian tiger back to the island where it was hunted to extinction more than 60 years ago. They announced that they had succeeded in copying small fragments of DNA from pickled tiger pups, suggesting that it might one day be possible to assemble the animal's entire set of genes and clone it back into existence.
"We are now further ahead than any other project that has attempted anything remotely similar using extinct DNA," said Mike Archer, director of the Australian Museum in Sydney which is carrying out the research.
"The Tasmanian tiger is an iconic Australian animal. It's woven in a complex web of guilt, because Australians made it extinct. We need to lift this burden."
But the project has been ridiculed on both scientific and ethical grounds, and there was much to be cynical about in the timing of yesterday's announcement.
The museum's statement was tied in to a forthcoming television documentary about the effort to clone the tiger - also known as the thylacine - and its press release claimed that scientists had "replicated individual Tasmanian tiger genes". In fact, as the museum's geneticist, Dr Karen Firestone, admitted to the Guardian yesterday, they have only replicated fragments of DNA, not entire genes, and very small fragments at that.
Nonetheless, the museum's methodical, emotionally motivated effort, combined with the relatively good condition of the preserved thylacine tissue, does put them closer to reality than comparable cloning dreams, such as restoring the mammoth.
The thylacine did have tigerish stripes along the rear of its spine, but it looked more like a dog than a cat, and was more closely related to the wombat than to either. Two feet high and up to four feet long without the tail, it was a hunting carnivore, with a gaping, sharp-fanged mouth, and a marsupial, with the female having a rear-facing pouch.
By the time Europeans reached Australasia, it was confined to a last redoubt on Tasmania. In just 70 years, the new settlers wiped the animal out, fearing attacks on their sheep. The last known animal died in Hobart zoo in 1936.
Conventional animal cloning involves three "parents": one to provide the DNA with a complete set of genes from the nucleus of an adult cell, one to provide an egg with most of its own DNA removed to "host" the source DNA and create an embryo, and one to act as a surrogate mother to bring the embryo to term.
With a long extinct animal, the first problem is to assemble thousands, probably millions of fragments of DNA into the right order of genes and non-gene sequences. First they have to be assembled into chromosomes, then into the complete genetic sequence, the genome.
Best hope
It is hard to see how scientists will be able to do this without a complete existing thylacine genome to act as a guide. They do not even know how many chromosomes a thylacine had. The best hope is to use genomes from similar animals for comparison - but no marsupial genome has yet been sequenced.
The next issue is how to make a thylacine embryo and carry it to term without a mother thylacine. Scientists hope to use another local marsupial, the Tasmanian devil, for eggs and surrogacy.
Even if virtual cloned thylacines were born, they would still have a part of their DNA from the egg donor species. It is doubtful they could be released into the wild without the upbringing they would get from parents of their own species.
"Using cloning to 'rescue' endangered species is bizarre," the independent GeneWatch UK said in a report last month. "The major factor which renders a species endangered is habitat loss. Cloning does nothing to preserve habitat."
• Last October, scientists in Italy reported the first successful cloning of an endangered species, the mouflon, a kind of Mediterranean wild sheep. A single cloned mouflon was born after DNA from dead mouflon ewes was inserted into 23 ordinary sheep eggs and the resulting seven embryos implanted into surrogate sheep mothers.
Less successful was the cloning of a rare species of wild ox, the gaur, by a US company, using ordinary cows for eggs and surrogacy. A gaur calf was born, but died two days later.
The same firm hopes to be the first to resurrect an extinct species - the bucardo, a mountain goat native to the Pyrenees. The last one was killed by a falling tree in January 2001, but frozen tissue samples should yield good DNA.
The longer a species has been extinct, the less likely a cloning resurrection becomes.
This could add a new twist to the phrase, "going the way of the dodo".
I hope they do this. And I hope they inadvertently produce a genetic monster that wreaks havoc on the ecosystem in Tasmania (or wherever the h*ll they plan to unleash this thing), proving YET AGAIN that it is foolish for mere morals, scientist or no, to tamper with things they don't even remotely begin to understand.
This d*mned hubris on the part of eco-freaks, who consider that man has godlike powers to rearrange the entire earth, are absolutely the worst menace to the health and well-being of homo sapiens that currently exists.
I agree. We have pictures. I'm not concerned as much by what we could "create", as the concept that we can "REcreate" the tiger.
One application for this type of technology in the future might be selecting animals to populate the surface of a terraformed planet- picking species that would be most suitable for the particular demands of that particular place. Also, It might be a lot simpler to accomplish a "Noah's Ark" type movement to other planets if we were to just carry a small container filled with different DNA samples rather than living breathing specimens.
This is what happens when scientists have too much time on their hands!
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Note: this topic is from 2002. |
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