Jackson Estuarine Laboratory

Physiological and chemical studies on Gymnodinium breve davis toxin


The marine dinoflagellate Gymnodinium breve was cultured under defined conditions and provided toxic material for chemical and physiological studies. Bioassay on mice and fish of ether extracts from cultures, confirmed that potency was related to numbers of cells extracted. A toxic component was isolated from these extracts and partially characterized by chromatographic and spectral methods. A molecular weight of 279 was determined by both osmometry and mass spectrometric analysis. The active material blocks neuromuscular transmission in frog sartorius preparations before rendering the nerve and then the muscle inexcitable to stimuli, but does not alter the transmembrane potential. Synaptic effects are blocked by curare. The primary site of action appears to be at the end plate although the specific mode of action is not clear. Physiological and pharmacological studies using mammalian intestine, vertebrate and invertebrate heart preparations and human serum, indicate anticholinesterase-like activity.

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