Venom hunt finds 'harmless' snakes a potential danger

December 14, 2003

Dr Bryan Fry is Deputy Director of the University of Melbourne's Australian Venom Research Unit and his discovery has shaken the foundations of reptile evolution, opened the door for a new class of novel drugs and, as many of these assumed harmless snakes are sold in pet stores worldwide, is causing experts to re-evaluate the relative danger of non-venomous snakes.

His findings appear in the journal Rapid Communications in Mass Spectrometry (August 2003), the Journal of Molecular Evolution (October 2003) and Molecular Biology and Evolution (in press). Fry has also received an Australian Research Council (ARC) grant of $250,000 over three years to continue this research.

Dr Fry is fascinated by venomous snakes and venom evolution. Last year he set off on a worldwide herpetological adventure to track down when and in what snake venom first evolved. The result was the ground-breaking discovery that snake venom developed only once in evolution and it did so about 60 million years ago, millions of years earlier than previously thought, and before the snakes we commonly think of as non-venomous even arrived on the scene.

"Contrary to popular belief, venom appears to have evolved at about the same time as advanced snakes started to appear. Even fangs and large venom glands arrived much later," says Dr Fry.

"This means the first venomous snakes evolved from the heavy-bodied swamp monsters similar to the anacondas of today. These snakes traded in their heavy muscle for speed and agility. Venom rather than muscle became the tool necessary for these snakes to capture their prey," he says.

The consequence of this is that venom is an inherent condition of virtually all advanced snakes, and that includes the assumed non-venomous species.

Dr Fry has now analysed the venoms from the many different snake lineages collected from his worldwide hunt and elsewhere, some of these were common pet-store snakes. He discovered that their venoms are just as complex as venoms from some of the world's deadliest snakes such as the cobras, puff adders and taipans.

"Some non-venomous snakes have been previously thought to have only mild 'toxic saliva'. But these results suggest that they actually possess true venoms," says Dr Fry.

"We even isolated from a rat snake, a snake common in pet stores, a typical cobra-style neurotoxin, one that is as potent as comparative toxins found in close relatives of the cobra," he says.

Fry's worldwide wandering has also boosted the number of what were previously assumed to be non-venomous snakes from a mere few hundred to more than 2000.

These snakes typically have smaller quantities of venom and lack fangs, but they can still deliver their venom via their numerous sharp teeth," says Dr Fry.

"But not all of these snakes are dangerous. It does mean, however, that we need to re-evaluate the relative danger of non-venomous snakes," he says.

Dr Fry trekked from Madagascar to Melbourne, dived for sea snakes in the remote South Pacific Islands, explored caves, climbed trees and milked over 2,000 snakes a year to gather his research findings.

"It was extreme science, but I had a complete blast doing it," he says.

As well as the evolutionary revelations, Dr Fry has also uncovered a vast range of new and unstudied toxins for toxinologists.

"The natural pharmacology that exists witihin animal venoms is a tremendous resource waiting to be tapped," he says.

"The toxin isolated from the ratsnake is an excellent candidate for use as a laboratory tool or even as a scaffold for use in drug design and development. The medical community may also benefit by exploring the effects of these unknown toxins in the human body."
-end-
**Images available: Dr Fry handling variety deadly snakes - underwater, in swamps, etc.

University of Melbourne

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