Toxins from Florida's Red Tide Dinoflagellate <i>Ptychodiscus brevis</i>

Toxins T17 and T34, isolated from Florida's red tide dinoflagellate Ptychodiscus brevis, cause a dose-dependent response in several in vivo and in vitro biological systems. Potent fractions responsible for in situ fish lethalities, respiratory irritation, and neurotoxic shellfish poisoning have been identified. The identity of potent fractions from three different research groups as well as the effects of chemical derivatization of the fractions on potency has been determined. Potency has been linked to membrane depolarization through endogenous sodium channels and specific binding to excitable membranes has been observed using tritiated toxin.