What's more, it turns out that the frogs evolutionarily stumbled across this resistance on at least three separate occasions, a testament to that mutation's usefulness. ( Read about a poison frog species discovered in Peru.) Epibatidine can't “recognize” the poison frogs' acetylcholine receptor, but acetylcholine can-sparing the frogs the effects of their own toxic brew. Acetylcholine and epibatidine bind to the nerve receptor at the same place, so if mutations changed the receptor's shape too much, acetylcholine wouldn't be able to do its crucial day-to-day job.īut other structural tweaks across the receptor compensated for this issue. Genetically speaking, the change had to be subtle. A Body Built for Poisonīut how did poison frogs start using epibatidine?Īfter sequencing the DNA of poison frog species that employ epibatidine, Tarvin and her colleagues found that the frogs' own receptors for acetylcholine were ever-so-slightly misshapen, results the team recently published in Science. “It's like cutting the wire at a fragile place, but just cutting it with a different tool,” says Butch Brodie III, a biologist at the University of Virginia and poison expert who reviewed Tarvin's study. In contrast, some species of poisonous newt use tetrodotoxin, which clogs up a pore that's key to conducting electric signals down a nerve. Just one frog's worth of epibatidine is enough to kill a water buffalo. In fact, it works so well it can hijack the role of acetylcholine, wreaking havoc. Some poison frogs carry a morphine-like compound called epibatidine, which works just like the compound acetylcholine, which sends messages between nerve cells. ( Find out how venoms could one day save your life.) In fact, many of the animal kingdom's most potent toxins target nerves in one way or another. In both cases, predators and prey alike want fast-acting toxins that can stop an animal in its tracks-making the nervous system an attractive target. These toxins don't have to instantly kill: Instead, predators regularly use venom that paralyzes their prey. Predators such as snakes and scorpions, however, use venom, which must enter another animal's body by physical trauma to properly work. The sound belonged to a new species of Poison frogs, also known as poison dart frogs. January 18th, 2017 - Deep in the Peruvian Amazon, in a region known as the Manú Biosphere Reserve, Shirley Jennifer Serrano Rojas heard something: a unfamiliar frog’s croak.
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