Sunday, 15 January 2012

Bring back, bring back, oh bring back my mammoth to me, to me

It's been claimed in the last few weeks that scientists are just a short stone's throw away from having the ability to bring back the woolly mammoth. For a number of years it's been suggested that this could be possible because we have a number of well-preserved frozen mammoths. Although any sperm they may have been storing at the time of death is long dead, the genetic material might be viable; just as deep frozen human sperm can be stored and used at a later date. The problem has been having enough male animals to act as donors. The idea is that a modern female elephant would be fertilised with mammoth DNA and the calf engineered to be female. Meanwhile, another elephant would be impregnated with the DNA of a different male to produce a male hybrid. The two hybrids could then mate to produce a more mammoth-like mammoth. Then that calf could then be impregnated by the sperm of a different male mammoth to create an animal with even stronger mammoth traits. Within three to four generations, scientists could create a breeding pool of mammoths. But, in order to avoid in-breeding, you would need more male donors that we currently have. Also, there is no guarantee that some of the hybrids wouldn't be sterile - as often hybrids are. And anyway, as an elephant's gestation period is around 645 days, we'd still be several decades away from a viable population.

However, there may now be a way to shortcut all of that. Russian scientists have discovered a thigh bone frozen in Siberian that looks to contain bone marow with genetic material suitable to use in cloning. Semyon Grigoriev, acting director of the Sakha Republic's mammoth museum, and his colleagues are now analysing the marrow and have announced a joint project with Japan's excellently named Kinki University to clone a mammoth within five years. The key to successful cloning is to replace the nuclei of egg cells from an elephant with those extracted from the mammoth's bone marrow cells. Doing this, according to the researchers, can result in embryos with mammoth DNA. What's been missing until now is woolly mammoth nuclei with undamaged genes. Scientists have been on a 'Holy Grail'-type search for such pristine nuclei since the late 1990s. Now it sounds like the missing genes may have been found.

But why bring them back at all? Isn't this all a little too Jurassic Park? The argument is that these animals shouldn't be extinct; that it was Man that killed them off and that the environment they lived in - the frozen tundra - is still available to them. All we'd be doing is 'making things right'. It wouldn't be like bringing back a Tyrannosaurus Rex and introducing it to an alien ecosystem. The last dinosaur (other then those that evolved into birds) disappeared 65,000,000 years ago while mammoths were still around only 10,000 years ago.

Similar procedures have been done before with mixed results. In 2009 it was reported that the recently extinct Pyrenean ibex was brought back to life briefly using 10-year-old DNA from the animal's skin. However, the cloned ibex died within minutes of being born, due to breathing difficulties. And the Roslin Institute who famously cloned Dolly the Sheep, have published a paper pointing out some of the difficulties involved. 'First, a suitable surrogate mother animal is required. For the mammoth this would need to be a cow (as best biological fit) but even here the size difference may preclude gestation to term," it said.'The success rate for such an experiment would be in the range of 1-5%. The second issue would be the need for viable whole cells. If there are intact cells in this tissue they have been 'stored' frozen. However, if we think back to what actually happened to the animal - it died, even if from the cold, the cells in the body would have taken some time to freeze. This time lag would allow for breakdown of the cells, which normally happens when any animal dies. Then the carcass would freeze. So it is unlikely that the cells would be viable. But let's say that one in a thousand cells were nevertheless viable. Then practical issues come into play. Given that we have an efficiency of 1% cloning for livestock species and if only one in a thousand cells are viable then around 100,000 cells would need to be transferred to stand any chance of success.'

All that aside, if the Russian/Japanese project works and we can bring back the mammoth, it does raise the possibility of resurrecting other species made extinct by Man. These could include the great auk, the quagga, the passenger pigeon, the golden frog, the Javan tiger and the Baiji river dolphin.

Personally, I'd love to see Mauritius once again populated with dodos, the sea full of Steller's sea cows (a kind of giant manatee hunted to extinction within 27 years of discovery in 1741) and thylacines (also known as marsupial wolves or Tasmanian tigers) once more prowling the forests.

The thylacine only became officially extinct in 1936, so there is footage of some of the last animals ever seen by humans. I can't help thinking that it would be wonderful to see them again for real.

Sources: Discovery News, Roslin Institute, BBC News.

No comments:

Post a Comment