An international team of researchers has discovered an “unprecedented” resistance to snake venom in an unlikely species, legless amphibians known as caecilians. Study published International Journal of Molecular Sciences. Associate Professor Brian Fry of the University of Queensland led the research, which he says is a solid model for a fundamental evolutionary concept of predator-prey interactions.

“Our work is a textbook example of how a single hunting pressure can initiate an evolutionary cascade in which the same defense mechanism occurs independently multiple times in different lineages of a species,” Fry said.

“In this case, the main predation pressure was the emergence of elapid snakes such as cobras and coral snakes, which are characterized by the evolution of a new way of delivering venom with their hollow, fixed, syringe-like teeth.

“Although sessileans are quite slippery, they are worm-like in their movement and speed and were incredibly easy prey for cobras and other snakes, using their fangs to kill them and then eat them.

“It would have been an absolute slaughter by the time the elapids grazed mainly caecilia, which contributed to the rapid spread of elapids in Africa, Asia and the Americas.

“Secilian’s ability to persevere and thrive despite these pressures is like a movie – how Doomsday survivors battle it out by changing the chemical landscape.”

The team studied caecilian species from all known families in the world, including species from Seychelles, where elapid snakes have never been exposed.

Lead author Marco Mancuso, of Vrije Universiteit Brussel’s Laboratory of Amphibian Evolution, said the study involved using tissue collections to sequence a portion of a neuromuscular receptor in worms that binds with snake venom toxins.

“We’ve shown that resistance to snake venom neurotoxins has improved at least 15-fold, which is unprecedented,” Mancuso said.

“A particularly interesting confirmation of the theory was that the caecilians in Seychelles were not resistant to snake venom, which is consistent with the fact that the elapids never reached these islands.

“This is an extraordinary signal for responding to such strong selection pressure that survivors are slightly less susceptible to the venom, and some have mutations that make them completely immune. “They were the ones who repopulated the land after the snake plague epidemic.”

Dr. The caecilians were able to achieve this unprecedented resistance to the venom using three different biological techniques, Fry said.

“One is to create a kind of roadblock that blocks the ability of toxins to reach receptors that would normally trigger a lethal response,” he said. “The second form of resistance is a change in the physical form of the receptor.

“As toxins turn into keys and are placed in a lock-like receptor, the shape change means the toxin no longer fits.” Finally, caecilians essentially use an electromagnetic ‘weapon’ that changes the charge when the toxin interacts with the receptor.

“The positive charge-to-positive repulsion increases exponentially as objects get closer together, like trying to force two magnets together.” This receptor pocket is normally negatively charged, so snake toxins have evolved to be positively charged to help direct attachment.

“The mutation in which the acceptor is now positively charged like toxins sprays toxins electrostatically.”

Dr. The results won’t lead to any new direct benefits, such as a new antidote for humans, Fry said, but the results have the advantage of showing an interestingly important evolutionary interaction for the next generation of scientists.

“Animals killing other animals and prey that have evolved to avoid predators is something that I think has always fascinated people, especially young people who are just starting out in science.” Source