Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

At the molecular level, the predator is the prey

07.04.2005


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.


Some garter snakes (Thamnophis sirtalis) have evolved the ability to eat super-toxic newts (Taricha granulosa) in the Pacific Northwest Photo by: Edmund Brodie III



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 some 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 channel."

David Bricker | EurekAlert!
Further information:
http://www.indiana.edu

More articles from Life Sciences:

nachricht Modern genetic sequencing tools give clearer picture of how corals are related
17.08.2017 | University of Washington

nachricht The irresistible fragrance of dying vinegar flies
16.08.2017 | Max-Planck-Institut für chemische Ökologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>