Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mutation in clams protects against paralytic shellfish poisoning but raises human health risk

07.04.2005


Just like people, clams can be affected by the toxins that cause paralytic shellfish poisoning (PSP), but scientists have now identified a mutation in clams that gives some protection. PSP toxins interfere with nerve function, and the mutation, which changes a single amino acid in a sodium channel, makes nerves less sensitive to those toxins.

The discovery is reported in the April 7 issue of the journal Nature. The authors suggest that it has wide ranging implications for the evolution of shellfish in the presence of toxic algae and increases the risk of PSP to people who eat clams by enabling contaminated clams to survive in the presence of toxins.

The report, "Sodium channel mutation leading to saxitoxin resistance in clams increases risk of PSP," was written by a team of scientists, including Laurie Connell of the University of Maine School of Marine Sciences. It describes differences in the responses of two soft shell clam populations -- one in the Bay of Fundy and the other in the Lawrencetown estuary in Nova Scotia -- to saxitoxin as well as tetrodotoxin, a powerful toxin derived from the puffer fish.



The lead author is V. Monica Bricelj of the Institute for Marine Biosciences in Halifax, Nova Scotia, and in addition to Connell, co-authors are Keiichi Konoki, Todd Scheuer, and William A. Catterall of the University of Washington; Scott P. MacQuarrie of the Institute for Marine Biosciences; and Vera L. Trainer of the National Oceanic and Atmospheric Administration in Seattle.

"Since the 1960s, it’s been known that different species of shellfish have different resistance to PSP toxins," says Connell. "This is the first time the source of that resistance has been shown. We now have a marker that can be used to determine if clams have this mutation. It’s easy to use and could help reduce the time of clam flat closures (related to red tide)."

Betty Twarog, a neurophysiologist who works at UMaine’s Darling Marine Center in Walpole, Maine, did research in the 1960s and 1970s showing that PSP toxin resistance varies among shellfish species.

In laboratory studies, the investigators exposed clams to PSP toxins and monitored the shellfish for mortality and potentially harmful changes in burrowing behavior. They found that clams that came from areas with a history of red tides had less sensitivity to the toxins than did clams from an area with no such history. They showed that nerves taken from the two clam populations also function differently, with those from exposed the population showing markedly less sensitivity to the toxins.

Tracking these differences down to the genomic level and comparing DNA sequences from the two populations enabled Connell to identify the single nucleotide mutation that corresponded with toxin resistance. She showed that the mutation changed an amino acid in a channel, a protein in the nerve cell membrane that allows sodium ions to pass through the membrane. Regulation of sodium is critical to nerve cell function. Without the mutation, the PSP toxins can bind to the sodium channel, shutting down the nerve and leading to paralysis.

The toxin acts like a cork in a bottle, preventing sodium ions from flowing through the membrane, says Connell. The mutation prevents the cork from sticking.

"This is a very conservative mutation in the protein. It was thought that the sodium channel was flexible at this location. We’ve shown that it is not, that it is rigid," says Connell. That could have implications for medical research, she notes, leading to new drugs for treatment of neuromuscular disease.

Because clams that possess the mutation are more likely to survive in red tide contaminated areas, the toxin and the mutation act together to influence the shellfish population, the authors conclude.

Laurie Connell | EurekAlert!
Further information:
http://www.maine.edu

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>