Venoms widespread in fishes

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The evolution of venoms in fishes is much more widespread than previously believed, says a new study designed to aid the search for new drugs.

Previous estimates on the number of fish species that produced venoms suggested that they were present in around 200 species. However, according to the results of a new study, 1500-2000 species should be presumed venomous.

The findings of the study have important consequences for those working in the bioprospecting arena, who study the proteins of organisms in an attempt to locate new candidates for potential drugs.

To date, most searches for new drugs have been undertaken on the venoms of snakes, where six stroke and cancer drugs are being trialled after being based around proteins found in snake venom.

William Smith of Columbia University and Ward Wheeler of the American Museum of Natural History produced a phylogeny - an evolutionary family tree - for the Actinopterygii to see how widespread venoms were.

Their findings, reported this week in the Journal of Heredity, suggest that fish are an untapped resource for bioprospectors looking for new drug candidates - with 1200 fishes in 12 clades being presumed venomous, and the possible maximum being considerably higher.

Smith and Wheeler wrote: "This assertion was corroborated by a detailed anatomical study examining potentially venomous structures in over 100 species.

"The results of these studies not only alter our view of the diversity of venomous fishes, now representing more than 50% of venomous vertebrates, but also provide the predictive phylogeny or "road map" for the effecient search for potential pharmacological agents or physiological tools from the unexplored fish venoms."

The study looked at the venoms of a huge range of fish, from the teeth of venomous blennies of the Meicanthus genus, to the opercular spine venoms of the Prehistoric monster fish, Thallassophryne amazonica.

The results of the study show that Wheeler and Smith's phylogeny is capable of foreseeing the presence or absence of venoms in the Actinopterygii with a high level of predictability.

For more details see the paper: Smith WL and WC Wheeler (2006) - Venom evolution widespread in fishes: A phylogenetic road map for the bioprospecting of piscine venoms. Journal of Heredity. June 1, 2006.