Researchers Chronicle Evolutionary Battle Between Snake and Newt

Researchers Chronicle Evolutionary Battle Between Snake and Newt

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SALT LAKE CITY (AP) -- Utah State University reachers who've been following the evolutionary battle between toxic newts and the garter snakes that prey upon them have discovered the molecular basis of the snake's defense against the poison.

As the garter snakes have raised their chemical defenses, the newts have become more deadly. The USU researchers found one newt (carries enough neurotoxins of the same type found in Japanese puffer fish to kill 50,000 mice or 10 people.

Shana L. Geffeney, a graduate student at the Logan university, is the lead author of the study published in the most recent edition of the journal "Nature." Her co-authors are Esther Fujimoto, Edmund D. Brodie Jr. and Peter C. Ruben of USU and Edmund D. Brodie III of Indiana University. Fujimoto is now at the University of Utah.

Their study examined the way genes regulating the cell's sodium channels changed in response to the neurotoxins in the newts' skin. Sodium channels are openings that let sodium move in and out of muscle cells, allowing the muscle to contract.

When the toxin attaches to a protein, sodium can't move in and out and the muscle is paralyzed.

The latest research found that the snakes' genetic makeup mutated so that the protein was shaped differently and the poison could not bind onto the new shape.

Snake muscles with the modified proteins were able to function even with high doses of the poison, the researchers found.

Geffeney told the Deseret Morning News that surprising to see changes in such an important part of the protein.

Another discovery was that separated populations of garter snakes differ in their amino acid sequences. In their separate habitats, at least two populations of garter snakes apparently evolved the defenses on their own.

One question the team would like to answer, she said, is "How many times has this elevated level of resistance evolved--"

The elder Brodie, father of the Edmund Brodie III, said that possibly other populations of garter snakes would show additional changes. "We know that the changes have evolved at least twice independently," he said.

As to which of the animals is winning the contest, Brodie said, "The snakes may be ahead for the moment, but it's variable, area to area."

(Copyright 2005 by The Associated Press. All Rights Reserved.)

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