November 20, 2008
With the announcement that the woolly mammoth genome has been sequenced, it seems natural to ask when we will finally see live mammoths. Since Jurassic Park, we’ve been tantalized by “promising” research that could some day soon lead to resurrecting long-extinct creatures. We even featured one of these researchers, Beth Shapiro, in last year’s young innovators issue (or, as it is know around the magazine office, the “I feel inadequate now” issue).
Well, I am here to throw some cold water on your plans for a mammoth-viewing safari vacation. We’re still a long way away.
There are a couple of ways you can start off when trying to recreate an extinct species. See, you need a copy of the creature’s DNA arranged in chromosomes and packaged in a nucleus. You can attempt to pull out an intact nucleus from some bone or hair or other remains that you find. This might seem like a good idea, especially since there was a study published a couple of weeks ago that did just this, pulling the nuclei out of mouse brain cells that had been frozen for 16 years. But 16 years in a freezer is far different from thousands of years in permafrost, freezing and occasionally thawing and refreezing. Finding mammoth nuclei with DNA that wasn’t damaged and contaminated would be difficult.
The other option is to work with a genome sequence and create chromosomes from that. The wooly mammoth genome, though, is only mostly sequenced (about 70%), and you need many copies of a complete sequence to make sure that there aren’t many mistakes left (sequencing isn’t foolproof). Then you have to organize the DNA into chromosomes, which hasn’t been done before, and create a nucleus out of them, which also hasn’t been done before. Oh, and you really need to do this multiple times.
But let’s say that you manage to find or create an intact nucleus with complete chromosomes and accurate DNA. Then you have to essentially clone the animal, transferring that nucleus to an egg—probably of an elephant—getting the injected egg to divide like a normally fertilized egg, and putting the egg into an elephant to carry it to term. This would be akin to cloning an elephant—but as you can probably guess by now, this also hasn’t been done before. (If you want a more detailed explanation of all the pitfalls on the path to creating a mammoth, Nature has a great article about this–and the whole mammoth study–though they are behind the pay wall.)
The bottom line is that if I’m lucky, I might see a mammoth before I die. But I probably won’t see a herd of them.
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