Nature Helps Lizards Beat Snake Venom in a Jaw-Dropping Twist

Australian skinks have developed molecular “armor” that prevents snake venom from shutting down their muscles, as revealed by a study led by the University of Queensland. Professor Bryan Fry from the University’s School of the Environment stated that uncovering how skinks avoid death from venom exposure may guide new biomedical methods for treating human snakebites (1^✔ ✔Trusted Source
Make Acetylcholine Great Again! Australian Skinks Evolved Multiple Neurotoxin-Proof Nicotinic Acetylcholine Receptors in Defiance of Snake Venom

Go to source). He described the evolutionary changes as remarkably clever, noting that these skinks have undergone tiny modifications in a vital muscle receptor called the nicotinic acetylcholine receptor. This receptor is normally targeted by neurotoxins which latch on and stop nerve-muscle signals, leading to rapid paralysis and potentially death.

Independent Evolution of Defense Mechanism

In what he called a striking example of a natural counterattack, Professor Fry explained that in 25 separate instances, skinks developed independent mutations at the toxin binding site to block the venom’s effects. This showcases the evolutionary pressure exerted by venomous snakes following their spread across Australia, during which time these predators likely preyed on unprotected lizards.

Astonishingly, similar genetic defenses have also evolved in other species like mongooses, which prey on cobras. According to Professor Fry, functional tests confirmed that the Major Skink of Australia, Bellatorias frerei, carries the exact same resistance mutation seen in honey badgers, a species famous for its immunity to cobra venom.

Mutations Create Venom-Blocking Shield

To see this precise type of venom resistance appear in both a mammal and a reptile is extraordinary, showing that evolution has repeatedly hit the same molecular target. The alterations in the muscle receptors include a strategy to attach sugar molecules that physically prevent toxins from binding, as well as a swap of the amino acid arginine at position 187.

The laboratory validation of these mutations was conducted at the University of Queensland’s Adaptive Biotoxicology Laboratory. Dr. Uthpala Chandrasekara, who led the experiments, described the experience as awe-inspiring. Synthetic peptides and receptor models were used to mimic how venom interacts with animal systems, and results showed that some altered receptors were completely unresponsive to venom.

Potential for Medical Innovation

Dr. Chandrasekara emphasized that such a minor change in a protein can determine survival or death when encountering highly venomous predators. These discoveries may eventually contribute to creating innovative antivenoms or therapies that counteract neurotoxic venoms.

Understanding how natural systems neutralize venom provides valuable insights for biomedical advances, she added. The more we learn about these natural defense mechanisms, the more tools become available for designing next-generation antivenoms.

This research project included partnerships with museums throughout Australia. The findings have been published in the International Journal of Molecular Sciences.

To conclude, the discovery of venom resistance in Australian skinks offers a fascinating glimpse into nature’s evolutionary ingenuity. The repeated emergence of the same molecular defense in unrelated species underscores the powerful selective pressure of venomous predators.

Reference:

1. Make Acetylcholine Great Again! Australian Skinks Evolved Multiple Neurotoxin-Proof Nicotinic Acetylcholine Receptors in Defiance of Snake Venom - (https://www.mdpi.com/1422-0067/26/15/7510)

Source-Medindia