Publication

2005-03

English

http://archimer.ifremer.fr/doc/2005/publication-605.pdf (0.20 Mo)

2005 Springer

Marcaillou-Le Baut Claire, Mondeguer Florence, Gentien Patrick

IFREMER Nantes, F-44311 Nantes, France.
CREMA lHoumeau, F-17137 Lhoumeau, France.

Journal of Applied Phycology (0921-8971) (Kluwer), 2005-03 , Vol. 17 , N. 2 , P. 155-160

13

Biology, Harmful effects

Liquid chromatography electrospray ionization mass spectrometry, Okadaic acid, Dinophysistoxins, Dinophysis acuminata

Blooms of Dinophysis in French coastal waters are implicated in most bans on marketing commercial bivalves. However, the relation between Dinophysis cell density and shellfish toxicity is not always consistent. Discrepancies may be due to the simple fact that it is nearly impossible to compare an integral over a few days (shellfish toxin content) and water samples. Furthermore, it seems that cells may have a variable specific toxicity. This work focuses on the variability in cell toxicity taking into account recent findings and using liquid chromatography coupled to mass spectrometry with an ion trap and electrospray interface. Esterified analogues of okadaic acid (DTX-4 and diol-esters) have been identified in cultures of Prorocentrum lima, another okadaic acid producer. These analogues are inactive on some protein phosphatases, contrary to okadaic acid, and seem to protect the cell from harmful effects by the toxin and to be enzymatically hydrolyzed during cell lysis. In order to document specific toxicity and to validate the presence of these analogues, D. acuminata concentrates were subjected to two separate heating and freeze/thaw procedures, respectively inhibiting or promoting hydrolysis. This paper reports on the high variability of D. acuminata specific toxicity and the presence of esters found in half of the samples only.