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The Puffer fish, also called Blow Fish or
Fugu: In terms of the potency of its toxin
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it is the most poisonous vertebrate in the
ocean and the second most poisonous vertebrate
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in the world after the poison dart frog.
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It is estimated that only a mere 1-2 mg of
pure puffer fish toxin could kill a grown
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man.
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To showcase just how little this is, a single
drop of water equals about 50 mg.
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This minute amount is enough to kill you or
around 10,000 mice.
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So let’s talk a little bit about this toxin.
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It is called Tetrodotoxin or TTX.
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It is named after the first group of animals
it was discovered in - the Tetraodontidae
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or the Puffer fish.
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Of all the neurotoxins it is probably one
of the most famous ones, frequently being
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featured in Movies and TV shows.
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It is also one of the most powerful neurotoxins
know and is about 10-100 more potent than
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black widow venom and 1000-10000 times more
toxic than cyanide when injected.
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Eating it is a lot safer but it is still deadly
nonetheless.
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If you had the choice between swallowing TTX
or the same amount of Plutonium you would
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have a better chance of survival going with
plutonium.
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But how does it actually kill you?
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Tetrodotoxin is one of a few neurotoxins that
binds to the so called voltage-gated sodium
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channels.
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In nerve cells these channels play an essential
role in the process that allows the electrical
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nerve impulses our body uses to send information
to be transmitted from one neuron to the other.
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By binding to and disabling these sodium channels
TTX prevents the conduction of these nerve
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impulses which ultimately shuts down the communication
between nerve cells and therefore the brain
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and the body.
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Puffer fish themselves are immune to the poison
due to a mutation in the protein sequence
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of the sodium channel.
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But for most other organisms it is lethal.
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When consumed, a low dose of Tetrodotoxin
typically produces tingling sensations and
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numbness around the mouth, fingers, and toes
as well as a feeling of euphoria.
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These Symptoms usually start to occur between
15 minutes to 4 hours after eating.
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Higher doses produce nausea, vomiting, and
diarrhea, breathing difficulties and irregular
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heart beat as well as loss of motor skills
and extensive paralysis.
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The paralysis will worsen to the point where
the sufferer will become unable to even move
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a finger all while being fully conscious.
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Death usually occurs after 4-6 hours but in
extreme cases after as little as 20m either
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due to paralysis of the heart or the respiratory
system.
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There is no approved medication or antidote
for it.
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In Puffer fish the toxin is concentrated mainly
in the ovaries, liver, intestines, and to
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less extent in the skin.
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Originally it was thought that they synthesize
the toxin themselves, however we now know
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that the toxin is instead produced by bacteria
that they likely obtain from their prey and
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that form a symbiotic relationship with the
animals.
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This is supported by the fact that puffer
fish born in aquaculture and fed on a TTX-free
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diet have no toxin in their body can however
become toxic once released into the wild.
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These bacteria can also be found in a variety
of other marine and terrestrial species that
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utilize Tetrodotoxin such as the blue ringed
octopus, parrotfish, sunfish, moon snails,
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several species of crabs and starfish as well
as some toads and newts, and these tiny marine
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flatworms that are one proposed food source
of TTX in Puffer fish.
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The levels of toxicity depend on the species,
the habitat and the time of year and seem
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to be at least in some form correlated to
the reproductive cycle as they are typically
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significantly increased during spawning season
– This might be to supply the eggs with
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the necessary TTX doses to keep them save
from predators but the toxin might also function
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as a sort of sexual pheromone for puffer fish.
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Experiments have shown that they are able
to smell TTX in the water, so the increased
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levels could mean that Puffer Fish are specifically
attracted to the most toxic partners.
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Large individuals have enough toxins in their
bodies to kill around 30 humans.
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That is enough to kill a fully grown great
white shark.
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With these levels of toxicity there aren’t
really any large predators that can realistically
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use them as prey at least not the most poisonous
species.
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Even an adult Killer whale with its 2-4 tons
of weight would probably feel very sick for
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a day or two after eating such a puffer fish.
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You would need to be a large baleen whale
to be heavy enough to not be severely impacted
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by its toxin and even they might enter a trance-like
state for a while.
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Dolphins have been filmed seeking out puffer
fish for exactly this reason.
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They don’t eat them but catch them in their
mouth and use them for a sort of chew toy
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for a while.
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The small amount of toxin released through
the skin is not enough to kill the dolphins
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but it seems to make them incredibly high.
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Is plausible that for a blue whale more than
300 times larger swallowing a puffer fish
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whole could have a very similar effect, but
such a scenario is of course unlikely at best
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given that baleen whales don’t typically
feed in the tropical coastal waters puffer
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fish are most commonly found in.
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This sensation of euphoria and the tingling
of the lips and tongue is also why puffer
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fish is considered a delicacy in many Asian
countries particularly Japan - That and the
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thrill of eating something that could theoretically
kill everyone in the restaurant.
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It is a bit like the food equivalent of Russian
roulette, at least that’s how it feels.
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Because of this, Tetrodotoxin poisoning is
and was historically by far the most common
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lethal marine poisoning.
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Archaeological evidence suggests that the
people of Japan have eaten Fugu possibly for
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more than 2000 years.
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Because of the inherent danger its consumption
was banned many times throughout Japans history
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and even today Fugu is the only food the Emperor
of Japan is forbidden to eat.
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Between 1886 and 1963 there were 6400 cases
of Fugu poisoning reported in Japan of which
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3800 ended in death.
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That’s an average of over 80 cases per year
and a mortality rate of 60%.
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Most of the deaths however came from eating
the liver which was and still is considered
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the tastiest part of the fish even though
it holds most of its toxin.
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Since the serving of liver was outlawed in
1984 the number of cases but especially the
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mortality rate has dropped significantly - down
to 3% in recent years.
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In Tokyo only a single person has died as
a result of Fugu poisoning in a restaurant
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in the last 30 years.
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So despite its reputation is actually pretty
safe to eat when prepared by a licences chef.
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Almost all of the roughly 40 yearly cases
of and puffer fish poisoning in Japan occur
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when inexperienced people try to prepare the
fish themselves which is needless to say extremely
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dangerous.
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But despite its deadliness this little fish
might actually safe lives in the future.
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Tetrodotoxin has been found to be about 3000
times more potent than morphine which makes
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it a very attractive candidate for pain medication
if we can find a way to release the toxin
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in a controlled and targeted way.
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Furthermore, because it doesn’t cross the
brain blood barrier like morphine does is
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doesn’t have the negative side effects of
opioids most notably their addictiveness,
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which has become a mature problem in the US
and other countries.
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And because the effects of TTX cause no lasting
tissue damage and are completely reversible
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with time it could become a long lasting very
effective alternative to morphine that could
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be safely administered for week’s maybe
months and therefore could be used to relieve
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chronic and neuropathic pain such as chemotherapy-induced
pain which is one of the most common reasons
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that cancer patients stop their treatment
early.
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With each Puffer Fish containing enough toxin
to treat dozens of people this tiny but deadly
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fish could therefore become one of our most
important allies in our continuous fight against
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cancer.11973
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