Magazine article Science News

Poison Frogs Upgrade Toxins from Prey

Magazine article Science News

Poison Frogs Upgrade Toxins from Prey

Article excerpt

For the first time, scientists have found a poisonous frog that takes up a toxin from its prey and then tweaks the chemical to make it a more deadly weapon.

At least three species of the 4-to-5-centimeter-long Dendrobates frogs of the New World tropics modify an alkaloid to create one that's about five times as poisonous, according to a team led by John W. Daly of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) in Bethesda, Md. The souped-up poison, one of a class called pumiliotoxins, ends up as a protective agent in the frogs' skin, the researchers report in an upcoming Proceedings of the National Academy of Sciences.

"It's an important thing, showing how chemistry connects the life of one organism to another," comments chemical ecologist Jerrold Meinwald of Cornell University. Although scientists have found that some creatures other than frogs customize a basic toxin for various purposes, "I don't know of any other examples of improving a defensive weapon," Meinwald says.

The new work grows out of years of research that started with a puzzle regarding dart-poison frogs, which belong to the family that includes Dendrobates. Frogs in three other families in South America, Australia, and Madagascar also carry poisons in their skin. However, when zoos and aquariums raise these supposedly deadly creatures, frogs from all but one Australian genus grow up harmless.

Daly and his collaborators in the early 1990s proposed that the wild frogs must be picking up the toxins from food and storing them in their skins. …

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