Paralytic shellfish poisoning toxin profile of mussels Perna perna from southern Atlantic coasts of Morocco.

During the monitoring programme of harmful algal blooms established along the south Atlantic coast of Morocco, a bimonthly determination of harmful algae and phycotoxins analysis in Perna perna was carried out from May 2003 to December 2004. Results of mouse bioassay (in organs and whole flesh) showed a seasonal evolution of paralytic shellfish poisoning (PSP) toxin. The mussel's contamination was associated with the occurrence in water of Alexandrium minutum. The PSP toxin profile obtained with high-performance liquid chromatography (HPLC/FD) revealed the dominance of gonyautoxins GTX2 and GTX3 and a minority of GTX1, GTX4 and saxitoxin (STX). This profile explains that the toxicity was mainly associated with A. minutum.

Purification and partial characterization of paralytic shellfish poison-binding protein from Acanthocardia tuberculatum.

A paralytic shellfish poison-binding protein (PSPBP) was purified 16.6-fold from the foot of the Moroccan cockles Acanthocardia tuberculatum. Using affinity chromatography, 2.5mg of PSPBP showing homogeneity on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was obtained from 93 mg of crude extract. The purified PSPBP exhibits a specific activity of about 2.78 mU/mg proteins and has estimated molecular weight of 181 kDa. Observation of a single band equivalent to 88 kDa on SDS-PAGE under reducing conditions suggested it to be a homodimer. The optimal temperature and pH for the purified PSPBP were respectively 30 degrees C and 7.0.

Comparative study on differential accumulation of PSP toxins between cockle (Acanthocardia tuberculatum) and sweet clam (Callista chione).

At the western Mediterranean coast of Morocco, the cockle (Acanthocardia tuberculatum) contained persistent high levels of paralytic shellfish toxins for several years, while other bivalve molluscs such as sweet clam (Callista chione) from the same vicinity were contaminated seasonally to a much lesser extent. In order to understand the causes of this prolonged contamination, a comparative study on PSP decontamination between sweet clam and cockle was conducted from November 2001 until June 2002. PSP toxicity was analysed by automated pre-column oxidation (Prechromatographic oxidation and LC-FD) in several organs of both species, namely digestive gland, foot, gill, mantle, muscle and siphon for sweet clams. The results showed that cockle sequester PSP toxins preferably in non-visceral organs (Foot, gill and mantle) contrary to sweet clam that sequester them in visceral tissues (digestive gland). The toxin profile of cockle organs indicated dominance of dcSTX, whereas sweet clam tissues contained especially C-toxins. Substantial differences in toxin profile between cockle and sweet clam, from the same area as well as from the composition of PSP toxin producer, Gymnodinium catenatum, confirm the bioconversion of PSP toxins in cockle.

Spatial and temporal evolution of PSP toxins along the Atlantic shore of Morocco.

A monitoring program for bivalve molluscs contaminated by algal toxins was established in 1992 at different stations along the Atlantic Moroccan shore. The presence of toxicity in bivalve molluscs commercially exploited was tested fortnightly using the mouse bioassay method. Results obtained from this surveillance indicate paralytic shellfish poisoning is responsible for bivalve molluscs contamination along the Atlantic coastline of Morocco. Toxin profile was established by automated pre-column HPLC/FLD in selected contaminated tissues. The study of individual toxins in mussel during a bloom in the northern Atlantic coastline in 1994 showed a very complex profile, typical to that obtained with cultures of the toxigenic dinoflagellate Gymnodinium catenatum isolated from the Iberian region. However, toxin composition of mussels and marine beans from later blooms in the southern Atlantic coastline in 1999 showed a strong resemblance with that of Alexandrium minutum, due to dominance of gonyautoxins 1/4. A minor contamination by G. catenatum due to the presence of decarbamoyl-saxitoxin is hypothesized.