Paralytic Shellfish Toxins: Their Origin, Characteristics and Methods of Detection: A Review

Abstract

Paralytic shelljkh toxin derivatives of saxitoxin (SKY) are a group of nonprotein toxins associated with shellfish that are derived intracellularly from dinoflagellate algal cells such as Alexandrium catanella, A. tamarensis, and Gymnodinium catenatum. Recent reports indicate that pure cultures of bacteria harbored by the dinoflagellates intracellularly are capable of producing several of the toxins. The fundamental structure is that of saxitoxin, with I7 derivatives presently recognized, all of which exhibit varying levels of sodium channel blockage of neurons, resulting in neurological symptoms and paralysis at suficiently high dosage. The toxins can be purified using adsorption chromatography on Sephuda (3-1.5 or Bio-gel P-2 followed by cation-exchange chromatography. The toxins are readily resolved with silica gel thin layer chromatography, and can be visualized by oxidation with H2 0, resulting in highly fluorescent derivatives. In recent years the mouse bioassay has been supplemented with ELISA assays, HPLC for resolution followed by post-column oxidative derivatization for detection and quantitation of the various derivatives, as well as a mammalian neuroblastoma cell assay, which is highly specific for sodium channel blocking agents.

Paralytic shellfish poisoning (PSP) toxins in North Atlantic right whales Eubalaena glacialis and their zooplankton prey in the Bay of Fundy, Canada

“…The potency of these neurotoxins in mammals spans more than 2 orders of magnitude across the various carbamate, decarbamoyl, and Nsulfocarbamoyl analogues (in order of decreasing toxicity). STX binds with high affinity to Site 1 of voltage-gated sodium channels causing blockage of neurotransmission (Shimizu 2000); the lethal dose of PSP toxins reported for humans ranges from 1 to 4 mg STX equivalents (STX eq) (Levin 1992). In humans, the onset of symptoms following toxin exposure is rapid (<1 h); however, the clearance of these compounds from the blood (primarily via the kidney) is also rapid and is generally complete within 24 h (Gessner et al 1997).…”

Risk management of shellfisheries

“…The low toxicity compounds can be converted to more potent toxins by heat and acidity. It follows, therefore, that food preparation may increase the toxicity of shellfish contaminated with PSP toxins (Levin, 1992).…”

A novel, simplified technique for preservation and rapid isolation of total RNA from the toxic dinoflagellateAlexandrium catenella(Dinophyceae)

“…Dinoflagellates such as Alexandrium spp. and Gymnodinium catenatum Graham are of particular interest to molecular geneticists because they produce a unique suite of potent neurotoxins (Levin 1992;John et al 2003). Paralytic shellfish toxins (PSTs) accumulate in the food chain and have been known to cause severe illness and even death in humans, marine mammals and birds with huge economic losses to the aquaculture industry (Armstrong et al 1978;Kan et al 1986;Hernandez et al 1998).…”