Take One Snail And Call Me In The Morning...continued
Conotoxins Mount A Multi-Pronged Attack
Olivera’s graduate student Craig Clark had other ideas. Clark realized that many of the conotoxins were probably designed to hit the nervous system of the fish. But in mice and humans, much of the nervous system is shielded from drugs and toxins by a system of impermeable blood vessels called the blood-brain barrier.
To circumvent this system, Clark injected conotoxins directly into mouse brains. Previously inactive, the individual toxins now caused the mice to either jump, sleep, scratch, drag their hind legs, swing their heads or shake.
The toxins caused so many behaviors because they were hitting so many different targets in the mouse nervous system. In the fish, their combined effect is formidable. Some toxins open channels on the outside of the fish’s nerve cells, switching the whole nervous system on at once and causing the fish equivalent of an epileptic fit. Other toxins block nerve to muscle communication; still others shut off all communication between nerves.
Cone snails use this chemical overkill so that death comes as quickly as possible. Any struggle would attract other predators, and the meandering cone snail is not about to run after a fish that is wounded but still mobile.
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