Could you tell me about the origins of the Frozen Ark project?
The actual origins of the Ark go back to 2004. It was the result of some research by my predecessor, Professor Brian Clarke, who was studying some endemic snail species in Tahiti in the South Pacific, where he saw the ill-advised introduction of a biological control snail predator that wiped out his study species. He realized, at that point, that if he didn’t do something, all of that genetic information, all the evolutionary research that he’d done, would be lost forever. So, he brought a lot of those animals back to the Zoological Society of London and Nottingham University. This really got him thinking that he needed to do something about rescuing genetic material from the species that were about to go extinct. That’s what motivated him to set up the Ark, which he did with his wife Anne Clarke.
The Ark is a useful metaphor for what you’re doing, but I’m guessing it deviates slightly from the two-by-two in a boat model. What does your Ark look like?
So, our Ark is really aiming to freeze genetic material, cells, cell cultures, tissue, DNA. Anything that basically harbors genetic material, either in viable cells, or as tissue samples, or DNA samples, so that that material isn’t lost and it’s maintained properly. That’s needed for a whole variety of different reasons but mainly because we need to understand the genetic diversity of species that are close to extinction if we’re going to manage them properly. Also so that we keep a record of the genomes of these organisms, if they do go extinct.
And so yes, we deviate from the two-by-two model very much, in the sense that maintaining the genetic diversity of two individuals is not enough for populations to remain viable in the future. So, we store lots of material from species, and we encourage organizations to collect and maintain collections of that nature, which properly represent the genetic diversity of the species they’re trying to save.
How many species have you collected material from since 2004? Hundreds? Thousands?
Thousands of species, and tens of thousands or even hundreds of thousands of actual samples. Species is one thing, but the number of samples is another. Although we have our freezers at Nottingham and at the Natural History Museum, the Frozen Ark is a federated partnership, so there are lots of freezers around the world that are collecting material that are members of the Frozen Ark, which is why I never really know exactly what we’ve got, because that’s an ongoing process. What we do is provide coordination, databasing, and advice to all of these nascent biobanks that are being set up, especially in developing countries.
What kind of DNA material is best?
The very best of all is cultured cells, so live cells. You can take cells from many tissues of the body, but people mostly take skin, and then you can grow them. For that, you need to culture the cells, which is technically tricky and there aren’t many places that do it—especially for lower vertebrate animals and invertebrates—and then you need to maintain those cell cultures at -200 degrees [Celsius] in liquid nitrogen, and then periodically draw them and regrow them. It’s technically demanding, but it is important. It can be frozen sperm. It can be frozen eggs. Next after [viable cells] is high-quality tissue, so tissue that’s been taken from live animals or animals that have just died. Muscle tissue, you know, that kind of stuff. If an animal, unfortunately, has to be euthanized or dies in captivity in a zoo, for example, or if it happens in the field, then freshly collected muscle tissue that we can then freeze down to -80 degrees [Celsius] is the next best thing, because that provides a large amount of DNA for future use as well. But we’re also very happy to collect other material, such as blood or DNA that’s already been extracted many moons ago. For some species, we’re even willing to accept non-invasively collected material like feces, hair, or urine, because they do contain small amounts of DNA, and that’s better than having nothing.