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Paris, 14 March 2011

Snake venoms have not revealed all their secrets

For several decades, snake venoms have been used in pharmacology to make new drugs. But a team of pharmacologists, clinicians, systematists and conservation biologists, headed by Nicolas Vidal of the Laboratory “Systématique, Adaptation, Evolution” (UMR 7138 Muséum National d'Histoire Naturelle/CNRS/UPMC/IRD), have shown that such venoms are largely under-exploited. They decided to pool their efforts to make full use of these resources in pharmaceutical compounds and to safeguard threatened species. The results of this study are published this week in the journal Bioessays.

At present, over 3000 species of snake live on Earth, where they occupy varied ecological niches. Most of them (around 2700) emerged and diversified after the K-T boundary and extinction of the dinosaurs 65 million years ago. This superfamily, known as Xenophidia (Caenophidia), includes the most advanced snakes, characterized by their venomous nature. Among these, snakes with venomous fangs, such as cobras, vipers and rattlesnakes, make up around 600 species. The remaining species, some 2000, are known as “Colubridae” or “colubrid snakes”. Since they do not have venomous fangs at the front of the mouth, they are generally harmless to humans. As they were thought to have no venom, they were neglected for many years. Recent discoveries(1) in snake systematics have shown that, due to this taxonomic bias, certain species have been underexploited, although they could have proved medically useful . 

Only over the last few years have scientists begun to take an interest in these usually harmless snake venoms. In this study, the scientists reviewed recent progress and looked at new technologies, such as High Throughput Screening(2), which could make it possible to identify and extract therapeutically useful molecules both quickly and efficiently. Snake venoms are also thought to be unexpectedly varied as their composition can differ, even among individuals from the same litter.

At the same time, a major biodiversity crisis is seriously threatening the snake populations on which these biomedical hopes are based. For this reason, systematists, conservation biologists, pharmacologists and clinicians need to join forces to preserve the biodiversity of these colubrid snakes, as much for their role in maintaining ecosystems as for their chemical diversity and the medical potential that they represent.

<em>Coelognathus radiata</em>, a slightly venomous colubrid snake from the tropical forests of Asia

© Freek Vonk

Coelognathus radiata, a slightly venomous colubrid snake from the tropical forests of Asia.


Notes:

1. N. Vidal, J.-C. Rage, A. Couloux, and S.B. Hedges. Snakes (Serpentes). Pp. 390–397 in The Timetree of Life, Oxford University Press, 2009
N. Vidal, S.B. Hedges. "The molecular evolutionary tree of lizards, snakes, and amphisbaenians." C. R. Biologies 332 (2009) 129–139
Bryan G. Fry, Nicolas Vidal, Janette A. Norman, Freek J. Vonk, Holger Scheib, S. F. Ryan Ramjan, Sanjaya Kuruppu, Kim Fung, S. Blair Hedges, Michael K. Richardson, Wayne. C. Hodgson, Vera Ignjatovic, Robyn Summerhayes & Elazar Kochva. "Early evolution of the venom system in lizards and snakes". Nature, Vol 439, 2 February 2006
Nicolas Vidal. "Colubroid systematics: evidence for an early appearance of the venom apparatus followed by extensive evolutionary tinkering". J. Toxicol.—Toxin Reviews, 21(1&2), 21–41 (2002)
2. HTS or High Throughput Screening techniques are used in the fields of biochemistry, genomics and proteomics to study and identify molecules with novel, biologically active properties in chemical libraries and target libraries.

Bibliography:

Freek J. Vonk, Kate Jackson, Robin Doley, Frank Madaras, Peter J. Mirtschin and Nicolas Vidal. "Snake venom: From fieldwork to the clinic". Bioessays, DOI: 10.1002/bies.201000117, March 2011

Contacts:

Muséum National d'Histoire Naturelle
Estelle Merceron
01 40 79 54 40 | presse@mnhn.fr

CNRS
01 44 96 51 51 | presse@cnrs-dir.fr


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