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Domoic acid (DA) is a potent toxin produced by bloom-forming phytoplankton in the genus Pseudo-nitzschia, which is responsible for causing amnesic shellfish poisoning (ASP) in humans. ASP symptoms include vomiting, diarrhea, and in more severe cases confusion, loss of memory, disorientation, and even coma or death. This paper describes the development and validation of a rapid, sensitive, enzyme linked immunosorbent assay test kit for detecting DA using a monoclonal antibody. The assay gives equivalent results to those obtained using standard high performance liquid chromatography, fluorenylmethoxycarbonyl high performance liquid chromatography, or liquid chromatography—mass spectrometry methods. It has a linear range from 0.1-3 ppb and was used successfully to measure DA in razor clams, mussels, scallops, and phytoplankton. The assay requires approximately 1.5 h to complete and has a standard 96-well format where each strip of eight wells is removable and can be stored at 4°C until needed. The first two wells of each strip serve as an internal control eliminating the need to run a standard curve. This allows as few as 3 or as many as 36 duplicate samples to be run at a time enabling real-time sample processing and limiting degradation of DA, which can occur during storage. There was minimal cross-reactivity in this assay with glutamine, glutamic acid, kainic acid, epi- or iso-DA. This accurate, rapid, cost-effective, assay offers environmental managers and public health officials an effective tool for monitoring DA concentrations in environment samples. [ABSTRACT FROM AUTHOR]

Understandably, commercial and recreational seafood harvesters are interested in how regulatory limits are set for various toxins in seafood. Here we summarize the origins of the safety levels for paralytic shellfish poisoning (PSP) and amnesic shellfish poisoning (ASP) toxins. PSP toxins consist of a suite of neurotoxins identified as saxitoxin, gonyautoxin, and their derivatives. The regulatory limit for these toxins (80 μg STX equiv. / 100 g shellfish) was established in the 1930s and is based on bioassays measuring toxic activity in mice. Amnesic shellfish poisoning (ASP) is a more recently discovered syndrome caused by one toxin, domoic acid (DA). It was identified in 1987 and the regulatory limit of 20 μg/ DA g tissue was established in the following year, based on the estimated DA dosage levels consumed by the first human victims of ASP. This study attempts to preserve the history of the origin of these regulatory limits, both of which have not changed and have effectively protected consumers of commercial seafood since their implementation. [ABSTRACT FROM AUTHOR]

Presents a study which examined the temporal changes in shellfish toxin levels in Puget Sound, Washington. Discussion on paralytic shellfish poisoning (PSP); Physical oceanography of Puget Sound; Frequency of PSP toxin closures in Puget Sound basins.

The potent marine neurotoxin domoic acid (DA) was detected in razor clams and Dungeness crabs on the Pacific Coast of the United States in 1991, resulting in temporary closures of these fisheries. Closures protect the health of human consumers of clams and crabs but impose significant economic losses to the communities that are dependent on these fisheries. Widespread closures, and in the case of the clams long-lasting ones, were necessary risk management strategies because ourknowledge of DA uptake and movement through the food web is very limited. In order to resolve some of these issues and provide health managers with better information concerning this toxin, experiments wereconducted on the accumulation and fate of DA in Dungeness crabs. Such information could provide enhanced safety, permit more efficient closures, and lessen the economic effect of future outbreaks. In the first study, razor clams. containing known concentrations of DA, were fed to Dungeness crabs for 5 days to determine the uptake of the toxinby the crabs. Twenty-four hours after the crabs ingested an initial 960 mu g of toxin, 260 mu g of DA (27%) was found in the hepatopancreas (HP) of the crabs. At the end of 6 days, 68% (2,850 mu g), from anaccumulated 4,220 mu g of ingested toxin, was present in the HP. DA was never found in the hemolymph or edible muscle of crabs in this experiment, but DA was found in the feces, indicating a route of deputation. The second study examined the denuration of DA crabs under fed and starved conditions. Crabs fed DA-contaminated clams for 4 days achieved an average concentration of 69.5 mu g of DA/g of HP. After 7 days, crabs that were fed toxin-free clams three times per week showeda 38% reduction in DA concentration, to 43.4 mu g of DA/g, whereas the average toxin concentration in the HP of crabs that were starved was reduced by only 4%, to 66.9 mu g of DA/g. In the last sampling, taken at 21 days, the concentration of DA in the HP of fed crabs decreased b [ABSTRACT FROM AUTHOR]