Print 71 comment(s) - last by fflintstone.. on Feb 11 at 5:13 PM

The tasmanian tiger, Thylacinus cynocephalus, seen here at the Washington DC zoo in 1902, has been extinct since 1936.  (Source: Wikipedia)

The mouse embryo, seen here, is now part thylacine -- it contains thylacine DNA which will effect its muscle and cartilage growth.  (Source: Andrew Pask and Richard Behringer)

Russian researcher Sergei Zimov is building a vast 160 sq km "Pleistocene Park" in northeastern Siberia near Alaska. He hopes to one day populate it with wooly mammoths and sabertooth tigers.  (Source: BBC News)
By injecting DNA sequenced from an extinct species into a mouse embryo, scientist have delivered a proof-of-concept, which could one day lead to full cloning of long-extinct species

Cloning extinct species has been a long standing dream of mankind.  Well, long standing since the 90s at least, when the movie Jurassic Park stole the imagination of audiences worldwide with a fictitious story in which scientists use DNA extracted from long dead dinosaurs to resurrect the beast through cloning (with disastrous results).  Since the movie, cloning science has advanced at a steady pace, and there has been increasing interest within the scientific community in cloning extinct creatures.

While it seems unlikely that dinosaur DNA pristine enough to produce a full genome map would ever be found, it would be reasonably easy to sequence other extinct creatures genomes such as the dodo, Neanderthals, wooly mammoths, and other more recent critters which researchers have recovered soft tissue samples (bone marrow, skin, etc) from.  However, such dreams were often scoffed at and remained the realm of pseudoscience.

They were derided -- until now.  In an exciting, successful new experiment, researchers at the University of Melbourne report that they have taken DNA from the extinct thylacine, commonly known as the Tasmanian tiger, and inserted it into a mouse embryo which continued to grow with the thylacine gene in place.  The process represented the first time DNA from an extinct creature was inserted into an embryo, effectively bringing "back to life" in part the extinct species.

Dr Andrew Pask, who led the research, says the experiment was the first time DNA from an extinct species has been successfully used "to induce a functional response in another living organism".  Professor Marilyn Renfree, a member of the team, states, "For those species that have already become extinct, our method shows that access to their genetic biodiversity may not be completely lost."

The findings of the team will be reported in the international science journal PLoS ONE this week. 

The Tasmanian tiger, whose scientific name is Thylacinus cynocephalus or thylacine for short, is an extinct marsupial from Australia that looked like a wolf.  The last surviving member of the species died in captivity at the Hobart Zoo in 1936.  The gene was extracted from tissue samples of flesh preserved in ethanol, which were donated by the Museum Victoria in Melbourne Australia.  The DNA was verified to be thylacine, and then was injected into the developing mouse embryo.

The gene injected was the thylacine Col2a1 gene, which controls cartilage and bone growth.  The mouse embryo was selected, partially because mice have a similar gene, also labeled Col2a1.

Dean of Science at the University of New South Wales, Mike Archer, is leading a project that aims to fully clone extinct animals, but he warns that success remains far off. He commented on the developments, stating, "The next question then is, well what if you did that with the whole of the DNA of the thylacine?  Could you in fact bring back a thylacine? Technically I think this is pretty difficult at the moment but on the other hand this is one very significant step in that direction and I'm delighted."

Despite the steep challenge, Professor Archer isn't giving up.  He states, "I'm personally convinced this is going to happen. We are working on a number of projects like this. I've got another group working on another extinct Australian animal and we think this is highly probable."

Aside from possibly leading to clones of extinct animals, the breakthrough also may yield scientific gains in biology and medicine.  Professor Richard Behringer, Deputy Head of the Department of Molecular Genetics, M.D. Anderson Cancer Center, at the University of Texas, says, "This research has enormous potential for many applications including the development of new biomedicines and gaining a better understanding of the biology of extinct animals."

Several groups are working to make real life Jurassic Park-style exhibits with cloned animals.  Some like a team in Japan are focusing on finding frozen gametes from ice age animals, while others are focusing on more traditional cloning

Perhaps most ambitious is the Pleistocene Park currently being built in northeast Siberia by Sergei Zimov.  Zimov introduced a grassland ecosystem along with 100 large mammals including
reindeer, horses and moose.  He plans on eventually introducing to the park wooly mammoths, extinct saber tooth tigers and prehistoric bears; all cloned of course.  On the possible threat of cloned tigers he states, "OK, so one or two people will be killed, like in India, but far more will die of alcohol in this place than from tigers."

While Zimov and others have thus far not revived any extinct species, advances in cloning may one day make their dreams a reality.  And with the new Australian breakthrough, that day seems to have come much closer.

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By 16nm on 5/20/2008 3:19:13 PM , Rating: 2
Hey Jason, do scientists have any theories regarding cloning extinct animals with JUST their DNA? I'm guessing they have some ideas on how to do it without the "somatic cell nuclear transfer" process.

By JasonMick on 5/20/2008 3:56:03 PM , Rating: 2
Hi 16nm,
A bit confused by your question, but I'll try to field it. Do you mean cloning without a donor cell/embryo? Such an approach would differ greatly from the current thought on how an extinct animal COULD some day be cloned.

The current thought would be to take a genetically and physiologically similar creature, ie for a wooly mammoth an elephant, take a zygote remove all the dna, implant surrogate DNA from the extinct animal, implant mitochondrial dna inside mitochondria, etc.

You do need some sort of base cell. However, eventually this cell might be able to created from scratch

but, that still wouldn't solve the problem of needing a womb at some point for the egg to at least partially develop in (amount of in womb-growth dependent on the Class of the species). Perhaps a synthetic womb could someday be invented, but there's no research that I know of on this.

However, even the basic method I first mentioned remains far away from actualization, and despite this breakthrough a fantasy of sorts. A big tricky spot would be replacing all the mitochondrial dna in the cell.

And the other really hard part is just getting the DNA. Only a few extinct species have had their genome fully sequenced.

And as far as dinosaurs, to quote a good story on cave bear genome sequencing, "Barring some fundamental misunderstanding about the nature of DNA decay, he says it is highly unlikely viable DNA will be recovered from 150 to 200 million year old Jurassic age samples."

Definitely a lot of research going on, but its hard to make partial clones with helpful tools ie. genetically similar surrogate mothers, let alone with some sort of purely synthetic cloning process (currently infeasible).

However, remember, if you know anything about science, you know you can never say never.

"The only true wisdom is in knowing you know nothing."

By 16nm on 5/20/2008 6:23:02 PM , Rating: 2
Yes, that's what I was asking about. It seems like a chicken-and-egg problem to me. A carrier, or womb, of the extinct species would seem to be needed but you can't have that until you've cloned the extinct animal. But, as you say, I guess if somekind of faux womb could be developed then this may be possible. This seems like the greatest complication to me given the complexity of the womb.

By tmouse on 5/21/2008 10:24:41 AM , Rating: 2
Its not that difficult in principle. Cross species surrogates have been done before, I think there has been horse/zebra and cross tiger subspecies (not totally sure). I know Tulane did a pigtail monkey surrogate giving birth to a rhesus monkey (they are thought to be several million years apart on the evolutionary tree)

By fflintstone on 2/11/2010 5:13:24 PM , Rating: 2
The chicken-and-egg question would seem to hint at how this can be done. If you think about it in terms of evolution and mutation, it is obvious that the egg came first -- at some point in time, a thing which was "NotAChicken" laid a mutated egg from which hatched a "Chicken".
For the resurrection process, you would presumably start with something genetically as close as possible to the target animal, then artificially mutate the eggs over a number of generations to arrive at the desired end result.

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