NEWSFLASH – Cloned Pets Aren’t Identical
OKay… this isn’t really a newsflash since the story I’m writing about was published almost two weeks ago, still — I’m still going to post it as one since it appears that pretty much everyone in the mainstream media missed the key point in this story.
Back on New Years Day the New York Times reported:
THE most difficult thing about the cloned puppies is not telling them apart, but explaining why they don’t look exactly alike. This was the problem Lou Hawthorne faced on a recent afternoon hike with Mira and MissyToo, two dogs whose embryos were created from the preserved, recycled and repurposed nuclear DNA of the original Missy, a border collie-husky mix who died in 2002.
Mr. Hawthorne, who is 48, is highly invested in the notion of likeness. With clones, after all, what good does similar do? It is Mr. Hawthorne’s biotech company, BioArts, which is based here in the Bay Area but has arrangements with a laboratory in South Korea, that performed the actual cloning.
He also has particular reason to be sensitive to questions that touch on the authenticity of the clones, given the history of his chief geneticist, Dr. Hwang Woo Suk of the Sooam Biotech Research Foundation in South Korea. Dr. Hwang is perhaps best known for fraudulently reporting in 2004 that a team he led had successfully cloned human embryos and stem cells. After the false claims were unearthed, he was fired by Seoul National University, where he did his research as a professor. But he is also widely acknowledged for having been involved in successfully cloning an Afghan hound in 2005.
A clone is defined as a genetically identical organism, cell, virus or DNA molucule derived from the reproduction of a singleprogenitor through asexual means. Plants are regularly cloned through leaf cuttings but cloning animals is a lot more difficult. We can’t cut the leg off, say, a slamander and then coax that leg to sprout a new creature (though in some cases the salamander can at least grow a new leg to replace the amputated one). No, cloning animals is a lot of work. To clone an animal you need to start with an unfertilized egg cell. You must then replace that cell’s nucleus with the nucleus of a diploid cell (i.e., one that has two homologous copies of each chromosome) of the animal to be cloned. Then you implant that that egg cell, which has - in effect, been ‘fertilized by two identical copies of the donor’s DNA and implant it in the womb of the surrogate. The important issue here is that while all of the nuclear DNA for the new organism will be identical to that of the donor — the mitochondrial DNA of the cloned individual will come from the egg cell donor.
While it may not govern traits like height, hair color or an innate fondness for polka music, mitochondrial DNA are believed to be important in the transmission and expression of many genetic disorder. Acquired mutations in mitochondrial DNA are also believed to play a key role in aging. And this may be a vital factor in cloning. Dolly, the famous cloned sheep died an early death. She was euthanized at the age of six (most sheep live 10 to 12 years) because of early onset arthritis and lung disease.
The mitochondrial DNA issue isn’t news to Hawthorne, the Times reports:
Elizabeth Wictum, associate director of the Veterinary Genetics Laboratory at the University of California, Davis, said that earlier this year, she and her staff had taken sets of DNA extracts from Mr. Hawthorne’s puppies and compared them with stored samples of Missy’s DNA, and concluded that the results were “consistent with clones.”
“The puppies had the same nuclear DNA as Missy, and different mitochondrial DNA, which is what you get from a cloned animal,” Ms. Wictum said. “If somebody were trying to, say, sneak in two samples from the same dog or an identical twin and claim that one was a clone’s, there would be no differentiation between the nuclear and mitochondrial DNA.”
Add in the develomental differences that can occur due to in vitro conditions and the fact that you can never even come close to replicating the environmental conditions that the original pet was raised in and it seems obvious that a clone can’t possibly be identical to its parent. There can be many differences between a clone and its single parent – and some of these differences may be vitally important. Cloning is still very much in its infancy and it’s difficult to say how it will be used in the future. Today much research is focused on tissue cloning. Possibly safer and certainly a lot less controversial than the cloning of entire animals, research on things like hair transplants, donor organs and meat is moving forward as is related work on genetically modifying animals to produce drugs and antibodies in their milk or eggs.
At a price tag of $170,000 each, I don’t see a big future for cloned dogs. And I’m’ thankful for that.