Toxins from fish and seafood

Question 1

Ex of Toxins from fish and seafood

Answer 1

Puffer fish toxin

Shellfish poisoning

Question 2

Puffer fish toxin produced by ?

Answer 2

Produced by puffer fish of the Tetraodontidae family:
- Balloon fish/ Blowfish/ Bubblefish
Globefish/ Swellfish/ Toadfish

Covered with tiny spines: Most toxic edible animal

Toxin is actually produced by a bacterium associated with the fish: Pseudoalteromonas haloplanktis tetraodonis
(Example of mutualism – both species benefit)

Question 3

The Edible puffer fish is ?

Toxin localises at which part of the fish?

Answer 3

Takifugu rubripes

Toxin is localised to the skin, ovaries, egg and liver

Muscle is a highly prized delicacy called Fugu in Japan
Must be prepared by specially trained and licensed chefs

Question 4

puffer fish Toxin structure

LD50
mechanism

Answer 4

it is tetrodotoxin

LD50 (mice) = 8ug/kg

Toxin blocks Na+ channels on motor, sensory and autonomic neurones

Question 5

puffer fish Toxin Symptoms

Answer 5

Symptoms occur in 5-20 mins:

• Numbness of lips, tongue and mouth
• Vomiting, diarrhoea, abdominal pain
• Drop in blood pressure
• Death by respiratory failure in as little as 30 minutes

Question 6

Recovery of puffer fish Toxin

Answer 6

Toxicity is usually only acute
If victim can survive for 18-24 hours then prognosis is good for full recovery
No antidote, can only relieve symptoms to some degree

Question 7

Other use of puffer fish Toxin

Answer 7

Haitian zombie powder contains tetrodotoxin

Sub lethal concentrations supposedly induce a zombie-like state in the practice of voodoo

Question 8

Different types of shellfish poisoning

Answer 8

Paralytic shellfish poisoning
Neurotoxic shellfish poisoning
Amnesic shellfish poisoning

Question 9

Cause of Paralytic shellfish poisoning

Answer 9

Shellfish often carriers of infectious bacteria and viruses – usually controlled adequately

Under some conditions shellfish can become suddenly toxic for several weeks at a time

Caused by blooms of dinoflagellate algae

Tend to happen in warmer weather

Question 10

Paralytic shellfish poisoning associated with what?
producing which toxin?
LD 50 of the toxin?

Answer 10

PSP associated with Alexandrium catenella and A. tamarense excavatum
which Produces saxitoxin:
Over 30 variants

LD50 (mice) = 260ug/kg body weight

Question 11

Paralytic shellfish toxin mechanism and risk arise from?

Answer 11

saxitoxin blocks Na+ channels similar to tetrodotoxin

Causes rapid paralysis and death by respiratory failure

Generally a problem in home-collected shellfish rather than commercial production

Question 12

Neurotoxic shellfish poisoning caused by ?

Chance of the lethal poisoning is?

Answer 12

Caused by shellfish contaminated with toxic phytoplankton
Culprit is Karenia brevis which grows in warm tropical waters

Lethal poisonings are rare

Question 13

Neurotoxic shellfish Toxic agent is ?

Answer 13

Toxic agent is one of a suite of molecules known as brevitoxins:

Brevitoxin A & Brevitoxin B

Brevitoxin- (1 -3; 7-10)

Question 14

Mechanism of brevitoxin

Answer 14

Brevitoxins also bind to Na+ channels and depolarise neurones

Question 15

brevitoxin caused Neurotoxic shellfish poisoning
symptom occurs after how long?
symptom last for how long?

Symptoms include:

Answer 15

Symptoms occur after 15 mins – 18 hours
Usually last less than 24 hours

Symptoms include:
Numbness / Tingling in mouth, arms and legs /
Incoordination / Gastrointestinal distress

Question 16

Amnesic shellfish poisoning caused by

Answer 16

Pseudo-nitzchia australis
Pseudo-nitzchia multiseries
Pseudo-nitzchia pungens

Question 17

Amnesic shellfish poisoning Toxic agent is ?
structure ?
mechanism

Answer 17

domoic acid
Structurally similar to glutamic acid – an endogenous neurotransmitter

Domoic acid binds to glutamate receptors 100-fold stronger

• -> Causes depolarisation of neurones
• -> Leads to toxic lesions in the hippocampus – part of the brain involved in memory

Question 18

How much consumption of shellfish required to cause Amnesic shellfish poisoning ?
Symptoms?

Other effects?

Answer 18

Consumption of 200 ug/g shellfish is enough to produce symptoms:

Gastrointestinal distress /
Dizziness / Headache / Disorientation
Persistent short-term memory loss

In severe cases seizures, paralysis and death

Algal domoic acid can influence marine animals and seabirds