Indirect enzyme-linked immunosorbent assay for saxitoxin in shellfish

An indirect enzyme-linked immunosorbent assay (ELISA) was developed for the detection of saxitoxin (STX). Antibodies against STX were demonstrated in rabbits 5 weeks after immunizing with STX-bovine serum albumin (STX-HCHO-BSA). In the ELISA, STX-HCHO-BSA or polylysine-STX was coated onto the microtiter plate, followed by incubation with standard toxin and anti-STX antibody. The amount of antibody bound to the solid phase was determined by incubation with goat anti-rabbit IgG peroxidase conjugate and a reaction with chromogenic substrate. Competitive indirect ELISA revealed that the anti-serum did not cross-react with either carbamoyl-neo-STX-sulfate or tetrodotoxin. The antibodies for STX cross-reacted with decarbamoyl-STX and neo-STX about 56% and 16% as much as they did with STX, respectively. The lower detection limits for STX, decarbamoyl-STX, and neo-STX in this system were about 25, 45, and 156 pg per assay, respectively. When STX added to clams or mussels was assayed, the detection limit for STX was about 50-100 ppb, and recoveries were in the range of 86.8-107%.

A combination fluorescence assay and Folin-Ciocalteau phenol reagent assay for the detection of paralytic shellfish poisons

Paralytic shellfish poison (PSP) profiles of crude shellfish extracts were determined by linear gradient elution from a Bio-Rad AG-50-X4 strong cation-exchange resin mini-column. STX, GTX2 and GTX3 were detected by fluorescence assay. NeoSTX and GTX1/GTX4 were detected with a Folin-Ciocalteau phenol reagent assay. The major toxicity associated with extracts of Mytilus edulis and Mya arenaria collected during a 1972 red tide off Hampton, New Hampshire, was due to the presence of GTX1/GTX4, with some activity associated with neoSTX, GTX2 and GTX3. STX was also present. Correlations to mouse toxicity are provided.

Distribution of paralytic toxins in California shellfish

Samples of Saxidomus nuttali and Mytilus californianus collected during the 1981 dinoflagellate bloom at Bodega Bay, California, were analyzed for the presence of paralytic toxins. Neck tissue of S. nuttali contained saxitoxin (STX) and neoSTX (95% of the total toxicity), whereas the bodies contained neoSTX and a mixture of the gonyautoxins. In a sample of M. californianus the presence of neoSTX and the gonyautoxins was demonstrated, whereas a second sample, collected at a different site, contained almost exclusively neoSTX.

The chemistry of brevetoxins: a review

The structure of the unique 'red tide' dinoflagellate neurotoxin, brevetoxin-B is presented and the experimental data supporting the chemical structure is discussed. A brief account of the other brevetoxins and their structural relationships is also presented. A biosynthetic scheme for the natural formation of the brevetoxin skeleton is proposed. Studies of the most toxic of the three pure brevetoxins, brevetoxin-A, indicate a skeleton differing from that of brevetoxin-B.

A competitive displacement assay to detect saxitoxin and tetrodotoxin

An assay is described which detects saxitoxin (STX) and tetrodotoxin (TTX) by their competitive displacement of [3H]saxitoxin from its receptor in rat brain membranes. The assay has a sensitivity of 0.15 ng STX/ml and 0.8 ng TTX/ml for buffer samples. The assay was also applied to detection of these toxins in unextracted human plasma and found to have a sensitivity of 0.5 ng STX/ml and 0.6 ng TTX/ml. The competitive displacement assay appears to be the most sensitive procedure yet for detection of STX and TTX.

Occurrence of saxitoxin in puffer fish

Three species of puffer fish, Takifugu poecilonotus, T. vermicularis and T. radiatus, were examined for the presence of toxic components other than tetrodotoxin. Saxitoxin, a paralytic shellfish toxin, was found in the livers, ovaries and digestive tracts of the first two species but not in the last species. The puffers are assumed to accumulate saxitoxin by feeding on bivalves that have ingested a toxic dinoflagellate Protogonyaulax tamarensis. Another toxic component is present in the liver of T. poecilonotus, but its structural relationship to tetrodotoxin or saxitoxin is questionable.

Occurrence of saxitoxin and other toxins in the liver of the pufferfish Takifugu pardalis

Highly toxic livers of the pufferfish Takifugu pardalis were extracted with acidic ethanol. The toxins extracted were partially purified by chromatography on Bio-Gel P-2 and then Bio-Rex 70, resulting in separation into three fractions I, II and III. ratios of total mouse units per fraction were approximately 0.1:100:0.01, respectively, with tetrodotoxin (TTX) as standard. By TLC, electrophoresis and a TTX analyzer, Fr. II was identified as TTX and, unexpectedly, Fr. III as saxitoxin, while Fr. I remains unidentified.

Comparison of the toxins of the blue-green alga Aphanizomenon flos-aquae with the Gonyaulax toxins

A toxic strain of Aphanizomenon flos-aquae (NH-1), isolated from a toxic bloom in a pond in Durham, New Hampshire, has been mass cultured in the laboratory. The toxin was extracted by ultrasonic disruption of the cells and purified by; (a) filtration through a 10 kilodalton filter, and (b) chromatography on a strong cation exchange resin column using 0.01 M, then 0.1 M, pH 5, sodium acetate buffer followed by 0.75 M hydrochloric acid. Mouse assays and fluorescence generated by hydrogen peroxide oxidation were used to monitor the fractions. Only a nonfluorescent toxic peak followed immediately by a fluorescent less-toxic peak were detected, both eluting with the hydrochloric acid fractions. The toxins were identical in behavior to neosaxitoxin and saxitoxin, respectively, when compared with elution profiles of the paralytic shellfish poisons from Gonyaulax tamarensis var. excavata and by paper electrophoretic and thin-layer chromatographic comparisons. The toxin profile appears to be different from that of a previously isolated strain of A. flos-aquae from Kezar Lake.

Size characteristics of the solubilized saxitoxin receptor of the voltage-sensitive sodium channel from rat brain

The saxitoxin receptor of the voltage-sensitive sodium channel from rat brain was solubilized with Triton X-100 and stabilized with phosphatidylcholine. The size characteristics of the detergent . phospholipid . receptor complex were studied by gel filtration and sucrose gradient sedimentation in H2O and D2O. The complex has Stokes radius = 80 A, S20,W = 12 S, v = 0.82 ml/ g, and Mr = 601,000 +/- 48,000. Assuming v = 0.73 ml/g for the saxitoxin receptor protein, the mass of the complex consists of 47.4% detergent and phosphatidylcholine and 52.6% saxitoxin receptor protein with Mr = 316,000 +/- 63,000.

[Determination of saxitoxin in canned shellfish (author's transl)]

Poisonings by saxitoxin-containing shellfish occur regularly in shore areas. The reason is increased growth of the dinoflagellates Gonyaulax tamarensis and Gonyaulax catenella. Due to the widespread consumption of canned shellfish these kinds of poisoning also occurs in continental areas. Therefore it is necessary to determine saxitoxin in canned shellfish products. Because of their sensitivity fluorospectrophotometric determinations of saxitoxin are preferred. However, the methods described in the literature can only be applied to fresh shellfish. Consequently a method for the determination of saxitoxin in canned shellfish was developed. This method offers the advantage that parallel with the fluorophotometric determination a biotest with mice can be carried out with the same extract for forensic corroboration of the results. The extent of saxitoxin occurence in Spanish canned shellfish in Austria in the years 1976-1979 is described. Apparently the producers of canned shellfish were able to solve this problem since mid - 1978.

[Poisoning after ingestion of mussels (mytilus edulis) (author's transl)]

Symptoms of poisoning occurred in 19 persons in the Rhein-Main region in October 1976, after they had eaten mussels (Mytilus edulis) imported from Vigo, Spain. Mild oral paraesthesias, tingling in the fingertips and feet were followed by generalised numbness and dizziness. All symptoms disappeared within 48 hours. They had been caused by saxitoxin which is produced by a dinoflagellate and accumulated in the mussels, as confirmed by testing confiscated samples of mussels. Toxin concentration ranged from 6000 to 20 000 MU (mice units) per 100 g mussel meat.