Genetic mutation gives snakes resistance to the venom of other snakes
Snake venom can pack a serious punch. In some species it contains toxic substances that affect the nerves (neurotoxins), which can kill small mammals in minutes and in some cases can even dispatch other snakes.
However, certain snake species are able to survive snake bites that would be deadly to others. A new study by researchers at the University of Queensland, Australia, has discovered that this phenomenon is down to genetic mutations that allow their nerve receptors to repel the neurotoxins, similarly to the way the two positive sides of a magnet repel each other.
Snakes such as cobras (Naja species) and kraits (Bungarus species) that prey on other snakes possess neurotoxins with positively charged sites on their molecular surfaces. Such sites allow the venom to bind with target nerves that have negatively charged receptors, and therefore paralyse the snakes’ prey.
However, the team found that some species, such as the Burmese python and the South African mole snake, which are both preyed upon by other snakes, have genetic mutations that mean their target nerve receptors are positively rather than negatively charged. As a result, their neurons repel the venom.
“It’s an inventive genetic mutation and it’s been completely missed until now. We’ve shown this trait has evolved at least 10 times in different species of snakes,” said Dr Bryan Fry, an associate professor at the university’s Toxin Evolution Lab.
The team made the discovery by developing artificial nerves with and without these specific mutations and
then observing their interactions with venoms using cutting-edge biosensors at the Australian Biomolecular Interaction Facility (ABIF).
“There’s some incredible technology at the ABIF allowing us to screen thousands of samples a day,” Fry said. “That facility means we can do the kinds of tests that would have just been science fiction before, they would have been completely impossible.”
“It’s an inventive mutation that’s been completely missed until now”