The causative agent for human food poisoning associated with the consumption of
cultured blue mussels, Mytilus edulis, in 1987 was identified as domoic acid from the
diatom Pseudonitzschia pungens f. multiseries (Todd, 1993). Domoic acid is structurally
similar to kainic acid, the most potent excitotoxin known to the mammalian
central nervous system (Olney et al., 1974), and an analogue of the excitatory neurotransmitter
glutamic acid that causes neuronal death in high concentrations (Shinozaki
and Ishida, 1976; Constanti and Nistri, 1978). Clinical symptoms of domoic
acid in humans include nausea, vomiting, diarrhoea, memory loss, confusion and
disorientation (Teitelbaum et al., 1990), and neurotoxicity of domoic acid to rats and
monkeys has been demonstrated (Tryphonas et al., 1990a,b). Mussels in the 1987
food poisoning incident contained up to 900 ,@g domoic acid, which as a kainic acid
receptor ligand resulted in extreme neurodegenerative disorders in humans (Quilliam
and Wright, 1989; Todd, 1993). Effects of such high levels of domoic acid on the
mussels were not investigated, although the relative toxicity has been reported for
other invertebrates (Maeda et al., 1987).