Monday, November 21, 2005

Why don't pufferfish poison themselves?

Fugu is a notorious sushi dish. It's made from pufferfish, and if improperly prepared, can cause the death of one who eats it. It's a deadly delicacy because pufferfish contain a neurotoxin called tetrodotoxin. It works by blocking voltage-sensitive sodium ion channels, which are partly responsible for action potentials, the electrical signal that most neurons use to send signals from one end of the cell to the other. Now, a new paper in Current Biology by Venkatesh and colleagues have worked out how pufferfish -- which have neurons, obviously -- are able to house all this toxin and not die themselves. It turns out that some mutations that change the composition of the sodium ion channel very slightly are all it takes. Beside making the puffership unpalatable to most organisms (except large brained primates who are like extreme cuisine), this tolerance to the toxin means pufferfish get to eat plenty of other organisms that accumulate the same toxin in their bodies and not be affected.

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