Farming the Sea
67
has been used as a muscular relaxant and as a palliative for terminal
cancer patients. As might be expected from the symptoms described
earlier, tetrodotoxin acts on the nerves and the muscles. Its rst
action is to block the passage of impulses along the nerves and later
it spreads to the muscles, preventing their bres from contracting.
If it blocks a nerve carrying sensation from a particular area of the
body then that part becomes anaesthetized and evidence shows that
tetrodotoxin is about 150,000 times more effective than the local
anaesthetic cocaine. Unfortunately the toxin’s ability to migrate to
tissues in other parts of the body probably rules out its direct use as
a local anaesthetic. Instead scientists who have now worked out its
chemical structure are trying to nd the part which produces
anaesthesia. Such information might well provide the chemical
‘plan’ on which greatly improved local anaesthetics could be
modelled.
Another animal toxin, holothurin, this time from the sea—
cucumber, has also some interesting properties. The Guam islanders -
collect sea cucumbers—long sausage—shaped animals related to sea
urchins and starsh—crush them up and throw the pulverized mush
into coral pools. Holothurin released from the crushed animals
paralyses sh, making them easier to catch. However, the property
more relevant to this discussion is the toxin’s ability to interfere
with the growth and development of cells. In this context, treatment
with holothurin has caused certain tumours in mice to regress. Once
more there is the problem of separating the benecial part from the
dangerous part of the chemical. Even if this is impossible, the dis—
covery of this remarkable property in holothurin suggests that
potential anti—cancer drugs may well be sequestered in the bodies of
other marine organisms.
The poison produced by that notorious jellysh, the Portuguese
Man—of—War, has already helped to make an important contribution
to medical science. Experiments in which animals were fed successive
doses of extracts from this jellysh led Charles Richet to the concept
of shock or anaphylaxis. According to this, the initial exposure of a
person to a biological material can increase the sensitivity and shock
arising from further exposure
to it. This line of reasoning led Richet
to an understanding of allergie reactions which earned him a Nobel
prize.
Not all marine poisons have such an obvious Jekyll and Hyde
potential. Take for example the mysterious sh—poisoning known as
67
has been used as a muscular relaxant and as a palliative for terminal
cancer patients. As might be expected from the symptoms described
earlier, tetrodotoxin acts on the nerves and the muscles. Its rst
action is to block the passage of impulses along the nerves and later
it spreads to the muscles, preventing their bres from contracting.
If it blocks a nerve carrying sensation from a particular area of the
body then that part becomes anaesthetized and evidence shows that
tetrodotoxin is about 150,000 times more effective than the local
anaesthetic cocaine. Unfortunately the toxin’s ability to migrate to
tissues in other parts of the body probably rules out its direct use as
a local anaesthetic. Instead scientists who have now worked out its
chemical structure are trying to nd the part which produces
anaesthesia. Such information might well provide the chemical
‘plan’ on which greatly improved local anaesthetics could be
modelled.
Another animal toxin, holothurin, this time from the sea—
cucumber, has also some interesting properties. The Guam islanders -
collect sea cucumbers—long sausage—shaped animals related to sea
urchins and starsh—crush them up and throw the pulverized mush
into coral pools. Holothurin released from the crushed animals
paralyses sh, making them easier to catch. However, the property
more relevant to this discussion is the toxin’s ability to interfere
with the growth and development of cells. In this context, treatment
with holothurin has caused certain tumours in mice to regress. Once
more there is the problem of separating the benecial part from the
dangerous part of the chemical. Even if this is impossible, the dis—
covery of this remarkable property in holothurin suggests that
potential anti—cancer drugs may well be sequestered in the bodies of
other marine organisms.
The poison produced by that notorious jellysh, the Portuguese
Man—of—War, has already helped to make an important contribution
to medical science. Experiments in which animals were fed successive
doses of extracts from this jellysh led Charles Richet to the concept
of shock or anaphylaxis. According to this, the initial exposure of a
person to a biological material can increase the sensitivity and shock
arising from further exposure
to it. This line of reasoning led Richet
to an understanding of allergie reactions which earned him a Nobel
prize.
Not all marine poisons have such an obvious Jekyll and Hyde
potential. Take for example the mysterious sh—poisoning known as