by In a lab at the University of Melbourne earlier this year, PhD student Pierre Ibri was running an experiment that could be a critical step in a prudent plan to save Australia’s endangered northern quoll.
In plastic trays were groups of tissue cells from another Australian marsupial – the common and mouse-like fat-tailed dunnart – which he was inoculating with the cane toad, an invasive amphibian that has killed a wide range of native animals. northern Australia.
Except some of these cells were different.
They had been genetically tweaked by a team of scientists at the University of Melbourne and Colossal Biosciences to develop the same resistance to the toad’s buafotoxin that other mammals in other parts of the world have developed over millions of years of evolution.
“We wanted to show that the cells had this resistance,” says Dr. Stephen Frankenberg, synthetic biologist and Ibri supervisor. “They did – something about 45 times more resistant.”
What happens next, the team hopes, could lead to a conservation revolution – the creation of a genetically modified mammal to deal with a threat that is now helping to push it towards extinction.
Frankenberg believes that the technical barriers to creating a quota against buffalo are few and that the team could have them living in captivity within five years.
One Australian native species that can eat cane toads is the rakali – or water rat – and Frankenberg says that although it is a species unique to Australia, it has likely retained some resistance to cane toads from its ancestors elsewhere. in the world.
If the northern quoll lived near cane toads for thousands of years, it is likely, he says, that they too would have evolved to resist the toxin.
“That resistance would develop as it has for other species,” he says, “but the quotas don’t have enough time.”
Like most of Australia’s native species, the northern carnivorous quoll has evolved in a landscape that lacks the butte. That is, until the cane toad was introduced in 1935 in a desperate attempt by the Queensland sugar cane industry to control bugs that were eating their crops.
Since then, the toads have spread across northern Australia. Professor John Woinarski, chief conservation biologist at Charles Darwin University, says that cane toads – along with feral cats and habitat clearing – were a key factor in pushing the northern quoll to endangered status.
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“Cuckoos are very effective predators,” he says. “They are the largest marsupial predator across much of northern Australia.
“But when they try to kill a cane toad, they grab them at the back of the head right where the toxin glands are mostly concentrated. They die very quickly and it’s an agonizing death.”
Woinarski, who is not involved in the genetic research in Melbourne, says efforts to save species from the cane toad have had limited success.
“New blue sky thinking may be our only hope now,” he says. “If this genetic engineering can be created, I think that’s a great innovation. Genetic engineering of a quoll is unlikely to affect other species.”
Woinarski says because quolls have up to 10 young per year but only live for a few years, a theoretical release of toad-resistant quolls could spread quickly through the population.
The team behind the quoll project is the same group, backed by US-based “extinction company” Colossal Biosciences, looking at genetic techniques to bring back the woolly mammoth and the quoll – a dog-like marsupial predator. of Tasmania who were being hunted to extinction. in the early 20th century.
The next step for Frankenberg and the team is to take a type of stem cell from the northern quoll and edit its genome to introduce the same resistance to bufotoxin that they successfully introduced into the quoll’s tissue cells.
Approaches to breeding a live animal with the resistant cane toad traits would then be tested, starting with a dunnart and then, hopefully, a northern quota. One approach would be similar to the one used to clone the famous Dolly the sheep. Dunnarts are close relatives of the quoll and the thylacine.
If they can then breed a quota using those stem cells, the team says that the offspring of those animals should also inherit the resistance.
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Professor Andrew Pask, who heads the Thylacine Integrated Genome Reconstruction Research Laboratory at the University of Melbourne, says cloning has not yet been achieved for marsupials. But he is confident that it could be done.
“This is simple [genetic] an array that would have evolved naturally. We are building up naturally occurring resistance and it gives the quoll a fighting chance,” he says.
Pask says a toad-resistant quoll could have a double effect. “They can then use the toads as a viable food source. Not only does this save the quoll, but we hope it could arm our native wildlife [against the cane toad].”
In the future, the technique could be used to genetically engineer other Australian species such as gobies, freshwater crocodiles and some snakes that cane toads can also be a deadly meal.
Frankenberg says what could go beyond creating the super quoll is getting regulatory approval to release them into the wild.
Professor Euan Ritchie, a wildlife ecologist at Deakin University, said: “If one day the toads were to be outcompeted by northern wagtails and other species, it could have a dramatic positive effect as it flows through food webs and ecosystems.
“Innovation like this is what is needed to help turn around Australia’s conservation history and better protect threatened species.”
