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 Cryo-electron microscopy achieves unprecedented resolution using new computational methods
24.03.2017 | DOE/Lawrence Berkeley National Laboratory

nachricht How cheetahs stay fit and healthy
24.03.2017 | Forschungsverbund Berlin e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>