Recent Studies on Marine Toxins.

Marine toxins generally cause two types of human poisoning, one due to ingestion of marine animals, another due to their attack e.g. stinging and biting. Recently, studies on, especially, the former toxins are going to be developed where even their origins as well as properties are pursued. Concerning tetrodotoxin (TTX), a typical marine toxin, the following several interesting facts are elucidated ; its wide distribution in animals and its toxification mechanism mainly through the food web, finally followed by production by marine bacteria. Other typical marine toxins e.g. ciguatera toxin, paralytic shellfish poison, diarrhetic shellfish poison are produced by marine microplankton, dinoflagellates. Consequently, fish or bivalves are toxified by their food chain. The structure of ciguatoxin has recently been elucidated. Many food poisoning incidents due to ingestion of toxic crabs have been known. The causative agent was already elucidated to be PSP. However, their origin remains unknown. Food poisoning incidents due to ingestion of mussel in Canada in 1987 occurred and the causative agent was elucidated to be domoic acid, an excitatory amino acid. Memory loss is featured by the common symptom of serious patients. The causative agent is suspected to be produced by a diatom Nitzschia pungens f. multiseries. Recent topics on studies of marine toxins will mainly be referred herein.