April 10, 2009
Student Discovers Link Between Diet, Venom In Snakes
A Welsh university student has recently discovered that the potency and composition of a snake's venom are largely determined by its location and diet.
Axel Barlow, a student at Bangor University in Wales, observed that the toxins in snake's venom appear to be specifically designed for the kinds of prey that they feed on. As part of his final-year paper, Barlow was studying the saw-scale viper, a snake whose natural habitat reaches from northern Africa, across the Middle East and as far east as India and Pakistan. The reptiles are known to feed largely on scorpions, which Barlow found to be particularly vulnerable to the snakes' hemotoxic venom.
The importance of his discovery, said Barlow, was that it has highlighted the significantly different chemical composition of venom even between closely related species of snakes. For the development of the anti-venoms used for the treatment of snake bites, this means that one size does not fit all.
The results of the study may prove beneficial for patients in African hospitals which predominantly import their anti-venom serums from Asian companies. Because the anti-venoms developed in Asia are designed to treat venoms from the eastern relatives of the African saw-scale viper, they are probably much less effective for treating African snake bite victims. This is particularly important for the African continent, where saw-scaled snake bite deaths are very common.
Barlow added that "[saw-scaled vipers provide a good model to study venom variation as different species have extremely different diets...This allows us to investigate the effects of evolutionary changes in diet within a single group of related snake species."
Dr. Wolfgang Wster, a herpetologist at Bangor and an expert in the field of snake venom, commented: "This study provides one of the most convincing pieces of evidence to date for the role of natural selection for diet in shaping snake venom composition...It is a key question in our understanding of venom evolution in snakes."
There are currently over 2,900 identified species of snakes on the planet, of which only about 450 are venomous. The annual number of snake bites to humans across the globe is estimated at about 2.5 million, resulting in roughly 125,000 deaths "“ a large proportion of which occur in Africa.
On the Net: