用化石还原出一个猛犸?

GUY RAZ, host:

Another biologist named Kevin Campbell wanted to get a blood sample from a woolly mammoth. The only problem is they died out more than 40,000 years ago. Now, you remember the visitors center in the movie "Jurassic Park," where an exhibit explains how they make dinosaurs?

(Soundbite of movie, "Jurassic Park")

Unidentified Man: (as Character) Using sophisticated techniques, they extract the preserved blood from the mosquito and, bingo, dino DNA.

RAZ: Now it's unlikely we'll ever be able to extract dino DNA. Dinosaur fossils are probably too old to preserve traces of DNA. But it turns out you can do it with woolly mammoths.

And Kevin Campbell, who works at the University of Manitoba in Canada, did just that and managed to resurrect mammoth hemoglobin. That's the substance in the blood that carries oxygen to different parts of the body. And by doing it, he found out a lot of things we didn't know about the mammoth.

Dr. Campbell, welcome to the program.

Dr. KEVIN CAMPBELL (Environmental and Evolutionary Physiology, University of Manitoba): Oh, thank you. It's my pleasure.

RAZ: What were our previous assumptions about woolly mammoths? Was it just that we thought they had these long coats and that's how they were kept warm?

Dr. CAMPBELL: That's all we knew. It's all we could determine from what we could see with our eyes. Hemoglobin is a physiological process and these do not fossilize. You know, what fossilizes are the bones and teeth. So up until this point, we've had no knowledge whatsoever of how any extinct animal has actually worked.

Now, what we're able to do is bring really key elements of these animals back in the lab and determined precisely how they worked. So the mammoth actually had to develop changes to its hemoglobin, and this allowed them to keep their extremities very cold for months on end, really we believe. And this would dramatically reduce their heat loss and hence their energy requirements, which would be very advantageous for them surviving, you know, winter in the high Arctic.

RAZ: So you extracted some DNA from fossilized bones of a mammoth and you managed to use that to resurrect mammoth hemoglobin, which is unbelievable. How did you then - you then inserted it into E. Coli. How did that then become hemoglobin?

Dr. CAMPBELL: What we're able to do is just simply get the sequence from the mammoth. And we also got the sequences from the living elephants. And then we used a method called site-directed mutagenesis. And site-directed mutagenesis is simply an ability to change, let's say, a letter A in a DNA strand into a letter C. So we took the mammoth changes and we put them into the living elephant DNA and we put that into the E. Coli. And then the E. Coli simply followed the recipe and from that we could, you know, take it out. And it was red and it bound oxygen and it released oxygen and it did everything that it would have done had it been inside that mammoth.

RAZ: It's incredible. Now, two years ago, scientists at Penn State managed to sequence a part of the mammoth's genome from a clump of hair. And they suggested at the time that it would take about $10 million to generate a real live mammoth. What's your take on that? What do you think?

Dr. CAMPBELL: What we did with one molecule, one very important molecule, is much like, you know, bringing a mammoth back as an entire baseball season. You can imagine how many pitches are thrown. And what we did was the opening day pitch. One protein to one mammoth is a very, very large step and there's so many technological hurdles yet to - I would love to see a mammoth but I'm not sure if I will.

RAZ: All right. Well, if you ever get close to making a real woolly mammoth, please give us a call because we will come up and visit you.

Dr. CAMPBELL: Yeah, I'll be opening my own little petting zoo.

RAZ: Little mammoth petting zoo?

Dr. CAMPBELL: Yeah. That would be quite the thrill, I'm sure, for children all over Manitoba.

RAZ: And the world, actually.

Dr. CAMPBELL: And the world.

RAZ: I think many kids around the world would like to pet a woolly mammoth. Dr. Kevin Campbell is an associate professor of biology at the University of Manitoba. He led the research team that resurrected hemoglobin from a woolly mammoth. Dr. Campbell, thank you so much.

Dr. CAMPBELL: Thank you. It's been a pleasure.