The Blow Fish

1
Tetrodotoxin
Nick Lowe Emily Bauer
Red fish,
One fish,
Blow fish
Two fish,
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Introduction
History Source Mechanism of Action Chemistry Case
Studies
3
Tetrodotoxin
Deadly toxin that blocks voltage activated Na
Channels.
4
The Puffer Fish

• Tetrodotoxin(TTX) is named after the order of
  fish from which it is most commonly associated,
  the Tetraodontiformes or the tetraodon
  pufferfish. 

5
Discovery
The deadly blowfish has been feared for thousands
of years.
The tomb of an Egyptian Pharoah was engraved with
the blowfishs image.
The Bible warned against eating fish without fins
and scales, like the Red Sea puffer.
The structure of tetrodotoxin was determined by
Robert Woodward in 1964.
6
Eating theHonorable Fugu
Fugu has been eaten in China and Japan for
thousands of years.
Fugu is one of the most expensive foods in
Japan. A single fish served in a restaurant, it
can bring in 200.

• Fugu's trade volume is rising because of
  people's curiosity in eating the toxic fish.

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A Fugu Chef
There are over 1,500 fugu restaurants in Tokyo.
Fugu chefs in Japan must pass a test and eat the
fugu he/she has prepared.
Only 25 of the applicants pass the test.
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Voodoo Tetrodotoxin?

• Voodoo is the predominant religion in Haiti
• Many believe in the existence of zombies
• Two explainations
• 1. Religious
• 2. Scientific
• Does Voodoo or drugs make zombies?

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The Serpent and The Rainbow

• In 83, ethnobotanist Wade Davis reported
  existence of Zombies in Haiti
• Named one of National Geographics Explorers for
  the Millennium
• Many remain skeptical of his findings
• Stresses psychobiological aspect of his
  hypothesis
• www.universalstudios.com/horror/video/serp4.mov
• www.universalstudios.com/horror/video/serp3.mov

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Is there experimental proof of Zombies?

• Zombie powder given to rats in the lab of Leon
  Roizin
• Some rats appeared comatose
• Certain rats immobilized for 24 hrs, then
  recovered
• Similar response in monkey
• RESULTS NEVER PUBLISHED!!!!!!

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Animals That Contain Tetrododoxin

• California newt
• Taricha salamander
• Parrotfish
• Frogs of the genus Atelopus
• Starfish
• Blue-ringed octopus
• Angelfish
• Triggerfish
• Goby
• Cod
• Xanthid crabs
• Boxfish
• Porcupine fish
• Globefish
• Horseshoe crab
• Marine snails

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What makes Tetrodotoxin

• Bacteria inside these animals make the
  toxin.
• These bacterial species, include strains of
  the family Vibrionaceae, Pseudomonas sp., and
  Photobacterium phosphoreum.

• Supporting Evidence
• Puffer fish grown in culture do not produce
  tetrodotoxin.

The blue-ringed octopus accummulates tetrodotoxin
in a special salivary gland and infuses its prey
with toxin by bite.
Xanthid crabs contain tetrodotoxin.
Tetrodotoxin in algae species Jania is produced
by a bacteria species Alteromas.
Puffer fish do not have the genes coding for the
synthesis tetrodotoxin molecules.
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The TTX-producing bacteria and host organisms
offer advantages to both partners.

• The bacteria get a safe place to live, eat,
  and reproduce The hosts use the toxin for
  predation or defense.

The blue-ringed octopuses employ TTX as a potent
venom for securing prey.
Newts arch their backs, revealing a
red-and-black surface, a common
warning sign in nature.
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Why arent host organisms effected?

• A single point mutation in the amino acid
  sequence of the sodium-ion channel makes it
  immune from being bound by TTX.

• Tetrodotoxin will not recognize the channel in
  these organisms.

The only known predators resistant to this toxin
is the common garter snake.
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Toxicity
"Weight-for-weight, tetrodotoxin is ten times as
deadly as the venom of the many-banded krait of
Southeast Asia. It is 10 to 100 times as lethal
as black widow spider venom when administered to
mice, and more than 10,000 times deadlier than
cyanide. William H. Light
One blow fish is enough to kill more than 30
people.
The estimated lethal dose for an adult, is one to
two milligrams.
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Action
Tetrodotoxin acts directly on the electrically
active sodium channel in nerve tissue.
It blocks diffusion of sodium through the sodium
channel.
This prevents the firing of action potentials in
nerve cells.
Tetrodotoxin acts on both the central and the
peripheral nervous systems, ultimately paralyzing
muscles. Respiratory arrest is the cause of death.
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Action potential

• The flow of Na? ions into the axon leads the
  axon to become positively charged.
• The inside grows increasingly more positive.

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Sodium Channels
Within the channel are two types of charged
particles forming the gates that control the
diffusion of Na.
The gate closes at polarization and opens at
depolarization.
open
closed
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Depolarization

• As Na ions flow into the axon the action
  potential is initiated.

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Repolarization

• The membrane of the axon is repolarized by the
  closing of Na channels and the opening of K
  channels.

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Transmission
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Muscle contraction
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When Na Channels are blocked an action potential
can not be initiated and muscles can not
contract. This is important for things like
Breathing
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Effect on the Heart
Tetrodotoxin can block neural and skeletal muscle
Na channels at 10 nM. It takes 100 times more to
block cardiac channels.
Cardiac muscle skeletal muscle Na channels
differ in structure and protein composition.
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Symptoms of TTX poisoning

• Symptoms occur within 30 min
• Initial tingling sensation in mouth
• Followed by high fever, headache,vomiting,
  lightheadedness, dizziness, feelings of doom,
  anxiety, and weakness
• Elevated blood pressure
• Bleeding lesions may occur over much of the body
• Respiratory arrest

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Structures
TTX and STX inhibit Na channels. Both bind
the outer enzyme complex. Produce similar
physiological responses. Local anesthetics are
also selective for some Na channels.
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Biosynthesis of TTX
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Synthesis of Tetrodotoxin
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Isolation of TTX

• Extracted from the gonads, liver, intestines, and
  skin of pufferfish

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Tetrodotoxin Mechanism

• Guanidinium moiety present on molecule
• charge at physiological pH
• Selective, complete, and reversible binding

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Binding Conformations of Tetrodotoxin and
Saxitoxin
Tetrodotoxin
Saxitoxin
These toxins bind to same sites on sodium channel
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Tetrodotoxin binds to the outside of the sodium
channel on a one-to-one basis.
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Uses of Tetrodotoxin
Tetrodotoxin is used as a tool because of its
selective blocking of the voltage-gated
Na-channel.
It was used to isolate channels, and identify the
structures of Na channels. 
Researchers have synthesized a labeled
3H-tetrodotoxin and a photoactivatable form which
may help locate the tetrodotoxin-binding site.
In diluted from it is also used as a painkiller
for victims of neuralgia, arthritis and
rheumatism.
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Antidotal Evidence
A 69-year-old woman was admitted to the Casualty
Dept. for food poisoning. Prognosis was bleak
In 1998, three chefs in southern California
collapsed soon after eating small amounts of
puffer fish brought back from Japan by a
co-worker.
Two women nearly died after eating puffer fish in
a Los Angeles restaurant.
In Australia, several people recently died soon
after being bitten by the blue-ringed octopuses.
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In July 1979, a 29-year-old college student in
Oregon suddenly collapsed at a party and later
died.


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Thanks!Have a great day
any questions?
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References

• http//www.chm.bris.ac.uk/motm
• http//www.britney .com
• Booth, William, Voodoo Science, Science. (1988)
• Hille, Beritle, Ionic Channels of Excitable
  Mebranes. (1992)
• http//www.vet.purdue.edu/depts/bms/courses/bms513
  /drgact01.htm
• http//www.american.edu/projects/mandala/TED/BLOWF
  ISH.HTM
• http//www.macalester.edu/psych/whathap/diaries/d
  iariess98/tal/tetro.html
• http//vm.cfsan.fda.gov/MOW/chap39.html
• http//home.earthlink.net/zh32/ttx.html
• http//gened.emc.maricopa.edu/bio/bio181/BIOBK/Bio
  BookMUSSKEL.html
• http//www.cellsalive.com/
• http//fugu.hgmp.mrc.ac.uk/fugu/pffp/tetrodotoxin.
  html
• http//vm.cfsan.fda.gov/mow/tet.html
• http//psych.hanover.edu/Krantz/neural/actionpoten
  tial.html
• http//www.chm.bris.ac.uk/motm/ttx/ttx.htm
• http//www.owlnet.rice.edu/psyc521/lectures/lec2/
  sld010.htm