With current technology, the idea of cloning mammoths by nuclear transfer is entirely fiction. To be sure, it is based on real-world fact, but in the same way Capt. Kirk’s USS Enterprise is based on a Boeing 747-400.
Cloning by nuclear transfer involves transferring a donor nucleus into an enucleated ovum. At present, and for the foreseeable future, nuclear transfer requires
pristine nuclei. Merely having an organism’s isolated DNA is not sufficient, you need whole undamaged nuclei from the cells of the organism and the nuclei need to contain
completely undamaged DNA. The
only way to achieve this is to clone from
living cells, or living cells that have been meticulously prepared and
frozen in liquid nitrogen so that they can be re-animated in cell culture at a future time. These are the
only ways that the nuclear DNA suffers no damage. There have been instances where dead animals have been cloned (eg. a prize breeding steer from Texas), but in all these cases samples were taken before death and prepared as I just described. Siberian tundra is cold but not nearly as cold as liquid nitrogen. A 10,000 year old frozen mammoth whose cells have undergone numerous freeze thaw cycles
will not contain useable nuclei for cloning a new animal as there will be DNA degradation and fragmentation. Even a little bit precludes the technique.
Confusion sometimes arises because people do not realize that most routine DNA analysis techniques do not require pristine DNA, and that the words “clone” and “cloning” have multiple meanings depending on the context. So it is possible the
clone<SUP>*</SUP> genes from the extracted mammoth DNA but not possible to
clone<SUP>*</SUP> a new mammoth using the extracted mammoth DNA.
<blockquote><SUP>*</SUP>The first instance of the word clone refers to isolating a relatively small piece of DNA that encodes a gene and inserting it into bacteria so that unlimited new copies of that DNA can be made for further analysis. The second instance refers to generating a whole new embryo by nuclear transfer and using a surrogate female to carry the resulting animal.</blockquote>
The linked article was interesting in terms of the ethics discussion and background info – thanks for the link.
But it didn’t provide much reality in terms of the science.
Under
Feasibility it says:
Experts in the cloning field have claimed that if DNA of suitable quality and quantity is recovered, there will be little difficulty in producing a clone.
Yes, well I would say that statement is rather specious and probably reflects the usual selective interpretation of “expert opinions” that one finds in science reporting. The “
if” in that statement is the stumbling block, and it’s a very
big “
if”. And even “if DNA of suitable quality and quantity is recovered” it is a far cry to then say that “there will be little difficulty in producing a clone”.
Why? The problem is mentioned here:
b) Body cells. As with Dolly, the cloned sheep, it is not necessary to have sexual reproduction to obtain a clone. In this technique, the egg of an Asian elephant would have the nucleus destroyed and replaced with the nucleus of a mammoth specimen. If successful, the resulting clone would be genetically all mammoth.
Since there are no mammoths in existence, a cross-species surrogate would be needed. This has already been achieved in other extant animals, but it adds a considerable degree of complexity to the whole procedure. The mammoth nucleus would need to be introduced into an elephant egg and the resulting mammoth embryo brought to term in an elephant female.
And the
Possibilities of Success section is somewhat hollow:
The technology of cloning is new and its potential mostly unrealized, but there are reasons to be optimistic:
There have been many recent cloning successes: sheep, calves, kittens, monkeys, guars, mouflon sheep, the Arabian oryx, the African quagga, and others.
Yes, and all these examples of cloning success were achieved using living cells. The rest of that section is mere speculation on what animal cloning might mean for endangered species. Interesting to speculate on but does not constitute any supporting evidence for Possibilities of Success in cloning a mammoth.
