PacheDolly the Cloned Mammoth? Not Likely
Posted by Richard Conniff on August 25, 2013
A piece by Robin McKie in the Guardian describes efforts to clone mammoths, and also provides some perspective on why it’s not likely to happen. Here are the key paragraphs:
The idea gathers little support from scientists such as [Adrian]Lister [of the Natural History Museum, London], however. “I very much doubt if the idea of cloning a mammoth is feasible,” he said, a point that was backed by the molecular biologist Professor Michael Hofreiter, of York University.
“There are two ways that you could try to clone a mammoth,” said Hofreiter. “The first is straightforward. You could simply look through the bodies we dig up in the Arctic to see if we could find one that had a cell that still contained a nucleus with a complete, viable genome in it.
“Then, employing the cloning techniques that were used to create Dolly the Sheep, we could put that nucleus inside an elephant embryo and then implant it into a female elephant, who would later give birth to a mammoth.
“The problem is that these creatures died many thousand years ago, when their DNA would have started to degrade, so the chances of finding an entire viable mammoth genome are essentially zero,” he said.
There is another approach, however. Scientists could use the scraps of DNA they do find in preserved bodies to build up a map of a mammoth’s genome. “Then you would use the same techniques that are employed in creating transgenic mice to make stretches of DNA – using your map as a guide – that you would then put into the embryo of an Asian elephant embryo which is the closest living relative of a mammoth,” said Hofreiter.
“Bit by bit, you would continue with this process with separate pieces of mammoth DNA until you had completely replaced the DNA in your elephant embryo with mammoth DNA. You would now have an embryo with a mammoth genome it. This would then be placed in a female elephant in whom the embryo would develop to birth.”
There are many difficulties with this approach, however. “A key point to remember is that elephants and mammoths each have about 4 billion DNA bases in their genomes,” said Hofreiter. “However, the maximum size of the DNA section you can add is about 1 million bases. So you would have to repeat the process sequentially 4,000 times – without mishap – to create your mammoth embryo. The chances of that happening are also essentially zero.”
Read the whole article here.