Scientists have uncovered the genetic basis for the production of domoic acid, a potent neurotoxin produced by certain harmful algae blooms.

       In the study, researchers have identified a cluster of genes related to the production of domoic acid in microscopic plants, or phytoplankton, called Pseudo-nitzschia. The work was funded by the National Science Foundation (NSF). They found the genes that contain the biological directions for how the toxin is made and these genes are "switched on" when Pseudo-nitzschia is producing domoic acid.

     Patrick Brunson, lead author of the study said, by identifying the genes that encode domoic acid production, they are able to question about what ocean conditions turn these genes on or off. Brunson is affiliated with the Scripps Institution of Oceanography (SIO) and the J. Craig Venter Institute.

       By showing how genes for domoic acid production are turned on, the authors suggest a way to connect the ocean conditions that drive algae blooms with the development of toxin production.

       Hedy Edmonds, one of the program director in NSF's Division of Ocean Sciences said that understanding how algae blooms become toxic, and what conditions cause that, are critically important and this study, offers a possible tool for monitoring algae blooms and predicting the production of toxin before it occurs.

       Harmful algae blooms often come in the form of red tides, so called because of the reddish tint they lend to the ocean waters. The blooms occur when phytoplankton grow rapidly, sometimes producing toxins that can sicken marine mammals and other species.

       Harmful algae blooms also pose a threat to human health when the toxins accumulate in seafood. A high dose exposure to domoic acid can lead to amnesic shellfish poisoning, a potentially fatal condition marked by seizures and short-term memory loss.

       Several states have been severely impacted by harmful algae blooms. The largest harmful algae bloom ever recorded happened in the summer of 2015 off the West Coast of North America from Alaska to California, and resulted in the closure of fisheries to protect consumers from potential shellfish poisoning.

       Scientists find it hard to forecast harmful algae blooms. The bloom causing organisms usually have very complex genomes. Scientist say that knowledge of the genes involved in domoic acid production will allow for better monitoring of algae blooms and aid in identifying the conditions that trigger toxin production.

       Senior author Bradley Moore, a chemist and geneticist at SIO and the University of California, San Diego's Skaggs School of Pharmacy and Pharmaceutical Sciences said that the genomes of the algae are so complex; hence, the biosynthetic pathways for marine microalgae toxins have remained elusive for some time. Now that they have a genome for Pseudo-nitzschia and a genetic pathway for domoic acid production, they are beginning to understand why these microalgae make a toxin and how that capability is activated. This new knowledge will better educate on how to predict and prepare for future toxic events.

       When phosphate in the ocean is limited and the amount of carbon dioxide increases, Pseudo-nitzschia can make large amounts of domoic acid and become harmful.Carbon dioxide in the sea is increasing above natural levels. Along with rising ocean temperatures, these conditions lead to more prevalent, more toxic, and longer-lasting blooms and domoic acid production.

       Researchers who work on monitoring and forecasting harmful algae blooms say the findings offer an increased understanding of the phenomenon, and will help to predict domoic acid events in response to climate change.

       The National Institutes of Health, the Gordon and Betty Moore Foundation and the U.S. Department of Energy also funded the research.

Figure. Dense cells of the harmful algae Pseudo-nitzchia during a bloom off the West Coast of North America.

Image Credit: NOAA

Source: www.sciencedaily.com