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 For a chimpanzee, one good turn deserves another
27.06.2017 | Max-Planck-Institut für Mathematik in den Naturwissenschaften (MPIMIS)

nachricht New method to rapidly map the 'social networks' of proteins
27.06.2017 | Salk Institute

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Ultra-compact phase modulators based on graphene plasmons

27.06.2017 | Physics and Astronomy

For a chimpanzee, one good turn deserves another

27.06.2017 | Life Sciences

Collapse of the European ice sheet caused chaos

27.06.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>