Navigation Links
At the molecular level, the predator is the prey

An evolutionary arms race between predatory garter snakes and their newt quarry is turning out to be something of an illusion. At the molecular level, another battle rages. And in this second, miniature realm, it's the newt who's the aggressor.

Biologists at Indiana University Bloomington, Utah State University and the University of Utah present evidence in this week's Nature that a toxin produced by the rough skinned newt, Taricha granulosa, has forced several evolutionary changes in the garter snake Thamnophis sirtalis or, more specifically, in the snake nerve cell protein that endures the toxin's attacks.

Embedded in the surface of garter snake nerve cells is tsNa(V)1.4, a tube-shaped protein that allows sodium ions to flow into the cell. When nerve cells' ability to move sodium in and out is hampered, paralysis and death can result. Tetrodotoxin (TTX), a powerful paralytic poison concentrated in the newts' skin, can bind to garter snake nerve cell channels and prevent sodium ions from flowing freely.

"These channels are absolutely fundamental to every aspect of nerve and muscle function and are highly specific gateways for sodium ions," said IUB biologist Edmund Brodie III, one of the paper's coauthors. "If the channels change too much or in the wrong way, they can't perform their basic, everyday functions. Sodium channel genes in different vertebrates are virtually identical to each other, but not in these snakes. We're finding a molecular arms race is driving rapid and repeated changes in the gene within this group of beasts."

For TTX to bind successfully to the sodium channel, the toxin needs something to bind to. At this moment in the garter snake's evolutionary history, TTX infiltrates a hole on tsNa(V)1.4's surface, binding to an aromatic amino acid and causing enough of a change in the sodium channel's shape to impair its function. Three of the four Pacific Northwest snake populations the scientists examined have evolved som e degree of resistance to TTX by making this aromatic amino acid harder for TTX to grasp -- or by removing it altogether.

One-thirtieth of the TTX normally found in a T. granulosa newt is enough to kill the average human being. The only organisms on Earth that can eat T. granulosa newts and survive are some T. sirtalis garter snakes. TTX is a defensive compound found in some puffer fish, octopuses and primitive chordates. It is used in low concentrations to treat morphine and heroine addicts. It's also the "zombie" drug used by Haitian voodoo ritualists.

Despite its action at the molecular level, the evolution of TTX in some organisms is viewed by ecologists as a defense mechanism. In the case of T. granulosa newts and T. sirtalis garter snakes, the interaction has gone far beyond that simple fangs-off arrangement, evolving into a lethal contest of toxification/detoxification one-upsmanship.

"One might think that this sort of change in the sodium channel would be too costly to the snakes," said Utah State University biologist Shana Geffeney, who conducted the gene expression experiments. "What will be interesting in the future is to understand if there is a balance between the costs of the changes in the channel pore structure on channel function and the benefits of changes in TTX binding."

The evolution of new traits often happens one of two ways, either by altering existing genes or by changing patterns and amounts of expression. The current Nature report shows that snakes' ability to detoxify TTX involves changes in the sodium channel gene.

"That is generally the story as it is developing," Brodie said. "Ecological arms races that go on between predator and prey are really driven at the molecular level. We have no evidence, nor reason to believe, that TTX is changing too, but rather that the toxin responds in quantity. Pour on more toxin, change the snake's sodium channel. Add more toxin, force further changes in the channe l."


Source:Indiana University

Related biology news :

1. Scientists ID molecular switch in liver that triggers harmful effects of saturated and trans fats
2. Source of molecular triggers in cutaneous T cell lymphoma identified
3. Plants, animals share molecular growth mechanisms
4. NYU researchers simulate molecular biological clock
5. Scientists reveal molecular secrets of the malaria parasite
6. Scientists identify molecular events that drive cell senescence
7. Researchers discover molecular mechanism that desensitizes us to cold
8. Findings have implications for tracking disease, drugs at the molecular level
9. Successful Test Of Single Molecule Switch Opens The Door To Biomolecular Electronics
10. By creating molecular bridge, scientists change function of a protein
11. NIH creates nationwide network of molecular libraries screening centers
Post Your Comments:

(Date:11/9/2015)... ) ... "Global Law Enforcement Biometrics Market 2015-2019" ... ) has announced the addition of ... 2015-2019" report to their offering. ... ) has announced the addition of the ...
(Date:10/29/2015)... LA JOLLA, Calif. , Oct. 29, 2015 /PRNewswire-USNewswire/ ... released a new report titled, "DNA Synthesis and Biosecurity: ... how well the Department of Health and Human Services ... was issued in 2010. --> ... advances, but it also has the potential to pose ...
(Date:10/29/2015)... NEW YORK , Oct. 29, 2015 /PRNewswire/ ... wearable technology, announced a partnership with 2XU, a ... accessories, to deliver a smart hat with advanced ... runners and other athletes to monitor key biometrics ... of the strategic partnership, the two companies will bring ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... CITY , Nov. 24, 2015 /PRNewswire/ - ... "Company") announced today that the remaining 11,000 post-share ... Share Purchase Warrants (the "Series B Warrants") subject ... were exercised on November 23, 2015, which will ... Shares.  After giving effect to the issuance of ...
(Date:11/24/2015)... , Nov. 24, 2015 /CNW Telbec/ - ProMetic Life Sciences ... today that Mr. Pierre Laurin , President and Chief ... at the upcoming Piper Jaffray 27 th Annual Healthcare ... on December 1-2, 2015. st , at ... one-on-one meetings throughout the day. The presentation will be available ...
(Date:11/24/2015)... ... November 24, 2015 , ... Whitehouse Laboratories is pleased to announce that ... facility will be strictly dedicated to basic USP 61, USP 62 and USP 51 ... to have complete chemistry and micro testing performed by one supplier. Management ...
(Date:11/23/2015)... ... November 23, 2015 , ... Shimadzu Corporation announces ... Nexera UC Unified Chromatography system. The award from R&D magazine recognizes Shimadzu’s Nexera ... the year in the analytical and testing category. R&D Magazine chose the Nexera ...
Breaking Biology Technology: