Intact mammoth chromosomes discovered

The field of sequencing extinct genomes has been rocked by a paper published in the Journal Cell, which heralds the discovery of one of, if not the, most intact specimens of mammoth DNA ever discovered. This sample, dating back 50,000 years, was found in the Siberian Permafrost, and contained genetic structures that were thought impossible to preserve over such a long period of time.

Shivani - This specimen from the mammoth was taken from a piece of the ear and it was so incredibly well preserved through the process of just dehydration and the permafrost that kind of froze it in place that it preserved the 3D structure of the DNA. And that's pretty rare because usually from ancient DNA you are scraping together different segments and trying to build a picture. But for once we've preserved the architecture of all the chromosomes and genetic material. And so we have an astoundingly accurate reading of the genome of the mammoth for the first time.

Will - How was that achieved? What were the conditions that allowed this to happen?

Shivani - The process of dehydration and just the lack of moisture in the air, and then the permafrost, it's very similar to how the Egyptians did the process of mummification. They just used hot air and drying, but in both scenarios there's just a lack of moisture and that allows biological tissue to really not decompose over time.

Will - Aylwyn, to throw over to you then, we've got this unique structure, this 3D structure. What information can be discerned from this that wasn't available previously?

Aylwyn - Well, I mean it is amazing. This is the kind of experiment that you can do with DNA from modern samples or present day samples. You could look at which bits of each chromosome are actually close to each other in the cell or even chromosomes themselves are looped up and packaged up amongst other proteins and other molecules. And that brings certain bits of the chromosome next to each other that otherwise if you just stretch the chromosome out in the line would be very far away. And it seems that those kinds of interactions, those proximity relationships are actually important for how the genome functions. It's important in determining and regulating the production of proteins in the cell and is actually part of how the DNA molecule works. So it's not just the sequence of the DNA, it's also the shape of the molecule itself and its interaction, its relationship with all of the other chromosomes, that actually are important in producing an organism's phenotype and how the cell works.

Will - Now that we have access to literally an extra dimension of mammoth DNA and we might start to be able to uncover how certain genes and how certain parts of the DNA interact with each other way better than we did before, in mammoths, aside from just knowing that and it being interesting, is there anything that it could actually be useful for?

Shivani - One of the salient findings from this was there was a specific gene, which is the EGFR and it was inactivated in these woolly mammoths and that leads to their really furry, hairy coat. But they compared this to the Asian elephant and the gene was active and they don't have this coat. So by finding interesting genes that code for different phenotypes or physical attributes, we can kind of see when temperatures change over time because of global warming. Are we able to do something about that and understand how the genes of an animal might allow it to survive these changing conditions or not?

Will - Every time a new sample of woolly mammoth appears, a biotech company, and this is no exception to this one, comes forward and goes, we would really like to be able to produce mammoths or produce elephant mammoth hybrids that resemble the extinct creature. And my question is why are people so obsessed with mammoths?

Aylwyn - I think there's a general consensus that they're pretty cool animals and it might just be about that really they're sort of iconic, prehistoric creatures. I don't know that scientifically it goes much beyond that and it's sort of a meaningless goal in my view anyway, to think about bringing back mammoths as a species. You know, even if you made a sort of elephant mammoth hybrid, a species is a lot more than just the genome of an organism. It's more than just all the molecules in it's cells, it's a whole population of organisms in an environment interacting with other species as part of an ecosystem. So unless you bring all that back, which is impossible, you haven't brought back the species. You've got this sort of chimeric creature living in a zoo. And maybe that would be a very cool zoo and maybe people would go and visit it and you might make a lot of money that way. But I don't think that's in itself an interesting scientific question. There are some very good scientists working, advocating for projects like this. And I think probably what they would say instead is that it's a sort of moonshot type project where, even if the goal itself is not achievable, in working towards it you will develop kinds of new technologies and get new scientific understandings and that those will have genuinely useful and transformative applications. I think that's what they would argue as the motive, although they may not make that explicit.

Shivani -There are people, private companies, or projects who run their own take on bringing mammoths back. And one of them claims that by bringing mammoths back, you can revitalise the mammoth steppe ecosystem, and that would actually slow the melting of the arctic permafrost. And I remember reading about this. So some people believe that by bringing them back you can restart an ecosystem and ancient ecosystem that slows global warming. So I think that it's very interesting, the kinds of different motives that people have for this.

Will - I feel like I know your answer to this, but for the pair of you, would you invest time and effort and resources into bringing back the mammoth?

Shivani - I think they're cute, but there are many cute animals that need saving that are alive today.

Aylwyn - Yes, exactly. I would rather invest those resources into projects that are addressing conservation today. Of course, that generally doesn't involve very complicated genome sequencing projects. So maybe that's why people don't get excited about them in the same way.