Occurrence of Paralytic Shellfish Poisons in an Ascidian Holocynthia roretzi

A paralytic poisoning case occurred due to ingestion of the ascidian Holocynthia roretzi caught from Ofunato Bay, Iwate Prefecture, in May, 1982. Ascidians were collected from the bay and examined for the contained toxins. The toxins were identified as paralytic shellfish poisons (PSPs) which were mainly composed of gonyautoxins 1-4, together with gonyautoxin 8 and its epimer. Besides, saxitoxin and neosaxitoxin were detected as the minor components. Some ascidians were analyzed for the anatomical distribution of PSP toxicity. Most toxic was the hepatopancreas (the highest toxicity, 1, 400 MU/g), followed by the branchial sac (32 MU/g), genital gland (30 MU/g), testa (20 MU/g), and mantle (19 MU/g). It was concluded from these results that PSPs were the causative substances of the poisoning.