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Occurrence and effect of algal neurotoxins in Nebraska freshwater ecosystems

Maitham Ahmed Al-Sammak, University of Nebraska - Lincoln


Algae are photosynthetic microorganisms that play important role in aquatic ecosystems as they are the primary producers in aquatic food webs. Several groups of algae are capable of producing toxins that impact aquatic ecosystems, especially managed systems. Cyanobacteria are the most important algae in freshwaters, and many species produce cyanotoxins including hepatotoxins and neurotoxins. The potent cyano-neurotoxins β- N-methylamino-L-alanine (BMAA), 2,4-diaminobutyric acid dihydrochloride (DABA), and anatoxin-a are especially critical with regards to public and animal health problems. Previous research has suggested that one or more of these cyano-neurotoxins may play a role in neurodegenerative diseases such as Lou Gehrig's disease, Alzheimer's , and Parkinson's disease in humans in several parts of the world (e.g. Guam). Biomagnification of cyano-neurotoxins though not well understood in aquatic systems is potentially relevant to both human and animal health. We proposed two routes of exposure to humans including; direct exposure through swimming, drinking, or other contact with contaminated water, and indirect exposure and biomagnification by consuming contaminated foods (e.g. fish) and aquatic plants. Because little is known regarding their occurrence in freshwater, we investigated the possibility of cyano-neurotoxins occurrence and bioaccumulation in several Nebraska lakes. Collection and analysis of 387 environmental and biological samples (water, fish, and aquatic plants) provides a snapshot of the occurrence of these compounds. A detection method using high pressure liquid chromatography-fluorescence detection (HPLC/FD) and liquid chromatography-tandem mass spectrometry (LC/MS/MS) was developed using solid phase extraction. Approximately 25% of the samples collected contained measurable levels of these compounds with BMAA in about 18.1%, DABA in 17.1%, and anatoxin-a in 11.9%. Toxicological investigation of the effect of BMAA in mice revealed a presumptive LD50 of 3 mg/gm B.W., and the lowest-observed-adverse-effect level at 2 mg/gm B.W. there were no histopathological lesions in brain or in other selected tissue specimens. Our study showed significant results, as BMAA, DABA, and anatoxin- a were found for the first time in water, aquatic plants, and fish samples collected from Nebraska freshwater ecosystem.

Subject Area

Toxicology|Surgery|Environmental Health|Public health

Recommended Citation

Al-Sammak, Maitham Ahmed, "Occurrence and effect of algal neurotoxins in Nebraska freshwater ecosystems" (2012). ETD collection for University of Nebraska - Lincoln. AAI3518908.