At first glance, there’s not much that obviously links an Australian skink to aggressive honey badgers or swift mongooses. But according to researchers at the University of Queensland, a vital similarity can be found at the biomolecular level—one that could lead to the development of new, more potent snake antivenoms.
Australia is home to over 100 venomous snake species, including some of the world’s deadliest. For most creatures—humans included—a bite from these poisonous reptiles can quickly turn fatal without medical treatment. When the first snakes arrived on the continent around 30 million years ago, prey didn’t stand much of a chance against the already optimized ancestors of the inland taipan and southern death adder. After generations of biological refinement, some species are now more evolutionarily equipped to evade their hunters. This often manifests physical traits like better agility, acute hearing, and improved vision. But for certain skinks such as Australia’s major skink, the lizard’s protection is embedded in specific genetic mutations.
“What we saw in skinks was evolution at its most ingenious,” study co-author and zoologist Bryan Fry said in a statement.
In the case of the major skink (Bellatorias frerei), resistance comes in the form of miniscule changes to a critical muscle component called the nicotinic acetylcholine receptor.
“This receptor is normally the target of neurotoxins which bind to it and block nerve-muscle communication causing rapid paralysis and death,” Fry explained.
Through functional tests, researchers noted the major skink’s mutation is identical to the one that protects honey badgers and mongooses from cobra venom. Fry added that it was “quite remarkable” to see the same resistance in both a lizard and a mammal.
“Evolution keeps hitting the same molecular bullseye,” he said.
Fry’s team documented 25 instances in which skink lineages have developed a “natural counterpunch” at the same binding site that blocks snake venom from doing its job. These also included a mutation that releases sugar molecules to physically impede toxins, as well as genetic change that substitutes a protein building block affected by venoms. To validate their observations, biotoxicologists including study co-author Uthpala Chandrasekara utilized synthetic peptides and receptor models to mimic a snake bite.
“The data was crystal clear, some of the modified receptors simply didn’t respond at all,” said Chandrasekara. “It’s fascinating to think that one tiny change in a protein can mean the difference between life and death when facing a highly venomous predator.”
Researchers hope that a better understanding of evolutionary neutralization remedies against snake venom can help scientists with antivenoms, therapeutic treatments, and other biomedical discoveries.
The findings are published in the International Journal of Molecular Sciences.
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