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Scientists use DNA technology in attempt to protect rare animal from extinction: 'We're just speeding up the process'

"Thereafter, they'd either learn to avoid toads, or they might exploit the toads as food, which could help turn the tide on cane toads."

“Thereafter, they’d either learn to avoid toads, or they might exploit the toads as food, which could help turn the tide on cane toads.”

Photo Credit: Getty Images

Scientists from a "de-extinction company" and the University of Melbourne are working to save the northern quoll from a toxic predator by altering its genes, New Scientist reported.

The endangered Australian marsupial is being pushed to the brink in part by the poisonous cane toad, an invasive species from Central and South America. The quolls are critically endangered in Australia's Northern Territory.

The cane toad invasion, which is proceeding westward by about 25-40 miles (40-60 kilometers) per year, is a major threat to their survival, along with habitat destruction and predation by cats. The amphibians were brought to the country in 1935 to control sugar cane-eating beetles and have since become residents' most hated intruder.

The toads multiply exponentially without natural predators and because females can lay 8,000-30,000 eggs at a time. They also eat everything in sight and can live five to 10 years. They secrete toxins that are deadly to would-be predators and other animals, though many of those species are adapting behaviorally and psychologically, allowing their populations to rebound.

Some animals that try to eat the toads, however, have not reacted quickly. That includes the northern quoll, and conservation efforts have been similarly unsuccessful. To aid the creatures, scientists are genetically engineering a "sodium-pump gene" so the quolls can become resistant to the toad toxin, according to New Scientist. The toxin inhibits a protein that keeps the element from rising to dangerous levels in predators' bodies.

"If the genetically engineered quolls had sufficient toxin resistance, then they would have a high chance of surviving a predatory attack on a cane toad," wildlife ecologist Jonathan Webb, who is not involved in the work, told the news outlet. "Thereafter, they'd either learn to avoid toads, or they might exploit the toads as food, which could help turn the tide on cane toads."

In a news release, Colossal Biosciences said its work with the Melbourne scientists marked "a major step forward" in saving the animal, but New Scientist noted many points of resistance. The team, which first used CRISPR gene editing to introduce toxin resistance in other marsupial cells in 2020, has yet to work its magic on quolls or any live animal. 

The recent breakthrough produced genetically edited cells of the dunnart — a related marsupial — that became 10 times more resistant to the toxin. The researchers anticipate that this resistance could eventually be expanded to help whole organisms, including quolls and other "susceptible native animals."

Marsupials are difficult to genetically engineer because their eggs develop hard shells after fertilization, preventing cells from being edited. Success would entail implanting resistant cells in enough northern quolls — whose population has decreased by 75% since 1935 — so their offspring could complete the spread of the inherited trait.

"Our toxin-resistance edit only changes a couple of DNA bases, which would probably arise by natural spontaneous mutation eventually anyway if quolls were to live with toads for the next few thousand years," Stephen Frankenberg of the University of Melbourne told New Scientist. "We're just speeding up the process so they don't go extinct before resistance can evolve naturally."

This effort is similar to those of scientists working to ensurefoodsecurity despite our rapidly warming world.

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