Pseudo-nitzschia produces which toxin?

• A. Saxitoxin
• B. Tetrodotoxin
• C. Domoic Acid
• D. Okadaic Acid

Answer: (C)

Domoic acid is the toxin produced by Pseudo-nitzschia. It’s a potent neurotoxin that acts as an excitatory chemical, mimicking glutamate at certain receptors and overactivating neurons, especially in the hippocampus. This can lead to amnesic shellfish poisoning, with symptoms ranging from gastrointestinal distress to memory loss and confusion, and in severe cases seizures. Shellfish that feed on Pseudo-nitzschia can accumulate the toxin, posing a risk to people who eat them. The other toxins listed come from different organisms and have different mechanisms—saxtoxin and tetrodotoxin block sodium channels to cause paralytic effects, and okadaic acid inhibits protein phosphatases leading to diarrhetic shellfish poisoning—so domoic acid is the correct association with Pseudo-nitzschia.