Quirks and Quarks

New Zealand could take drastic steps to save the Kiwi

To protect its native animals, the country is considering a controversial technology known as gene drives on invasive predators.
The government is hoping a rat-free countryside will give a boost to native birds, including the iconic kiwi. (John Stone/New Zealand Herald/Associated Press)

New Zealand has a predator problem. And it's so bad, the country is pulling out all the scientific stops make the country predator free by 2050. 

How? The country is considering the use of a cutting edge, and controversial technique. It's called  "gene drives." This technology forces a genetic change through an entire population, rendering the target species unable to reproduce.

In this Quirks & Quarks feature story, Bob McDonald speaks with Dr. Neil Gemmell. He's a professor of Reproduction and Genomics at the University of Otago in Dunedin. He's also part of New Zealand's Biological Heritage group whose aim is to protect the country's natural biodiversity. 

Bob also speaks with Dr. Paul Thomas, a biochemist at the University of Adelaide. 

The following interview with Dr. Thomas has been condensed and edited for clarity.

Bob McDonald: Take me through the approach your lab is taking with gene drives in mice.

Paul Thomas: We've seen very interesting papers that have come out over the last couple of years using invertebrates, so mosquitoes and flies, showing that these gene drives can work and they can work quite efficiently.

So what we've thought about is how we could test to see whether this technology can be applied in different species, in particular in mice. Mice are a known pest species but they're also attractive for modeling this kind of new technology because it's relatively easy to manipulate their genome. So in other words we can create the mice in a laboratory setting to test whether gene drives can work in mammals.

BM: What is the genetic element there that you're using to actually create a gene drive?

PT: The gene drive itself is like a molecular pair of scissors and it can cut virtually any way within the genome. To make those scissors active what you need to do is to create strains of mice that contain the components of the gene drive. And essentially those components are two different genes, that when they come together in the same organism, they create that pair of scissors.

What I would also like to make sure that everyone is aware of is that we are doing these experiments in the safest way possible. So we are testing gene drives in mice by creating special laboratory strains.

But also if these mice were to escape from our laboratory setting they would have no activity in the wild. So it's a very safe form of testing of gene drives that we're undertaking.

A rat attacks a bird nest in Waikanae, New Zealand. The introduction by humans over the centuries of pests such as rats, cats, dogs, stoats, ferrets, weasels and possums have made the battle to save New Zealand's endemic animals so tough the government has decided to pull out all the scientific stops to make New Zealand predator free by 2050. (AP Photo/Nga Manu Trust,David Mudge)

BM: So once you have the molecular scissors, what is the element that goes on to make the mice have only sons or only daughters?

PT: In addition to having the scissors sitting there in the genome you can add in extra genes. These are called cargo genes. And if you want to create a completely male population you can add in a gene called SRY. This is a natural trigger gene that normally turns on the male differentiation pathway. So if you attach your SRY gene to your gene drive what happens is that all the progeny from a gene drive individual will become male.

BM: How far along are you in this process?

PT:We have created the strains that contain the scissors and we're now setting up our very first crosses to determine how efficient the gene drive replication mechanism is. So we're literally a few weeks away from understanding for the very first time how well gene drives will work in mammals.

BM: You say that you're taking great precaution to make sure it stays in the laboratory but if this technology does get out, what can be done to put the "gene-e" back in the bottle?

PT: That's a very good question. There are several strategies that people have discussed, mostly theoretical at this point, as to how to reverse the activity of a gene drive. One is to use a second gene drive on on top of the original to revert the genome back to its original state. Another approach is to again use gene technology to inhibit the first gene drive.

BM: But using a gene drive to solve a problem that's come up with the gene drive is sort of fighting fire with fire.

PT: I completely agree with you. It's not a great argument to say that you could fight a gene drive by releasing a second gene drive.  What we're hoping to do is to inform that debate by doing safe laboratory experiments. It's a long way from deploying that technology in the field. And that's a massive decision and one that needs to be carefully considered with a lot more information.