Drug Testers Think Small...continued
Replacing Lab Mice with Worms
The tiny worm Caenorhabditis elegans only lays eggs when it is well fed. But give it some Prozac, or any number of similar anti-depressants, and these worms will lay eggs even when the cupboard is bare (or, in their case, when there are no bacteria to eat).
To Carl Johnson this is more than a pharmacological curiosity. Giving a chemical to a worm and looking for egg laying is a whole lot easier and safer than giving the same chemical to a human and testing for a reduction in depression. If he wants to find more chemicals that act like Prozac on humans, the worm test is a good place to start. Based on this concept, Johnson helped form NemaPharm, Inc., which is now part of AXYS Pharmaceuticals (South San Francisco, Calif.). Devgen N.V. (Ghent, Belgium) is using a similar approach.
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The Ultimate
Worm Dispenser |
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NemaPharm’s testing tool is its unique worm dispenser. Fast-moving fluid straightens the worms out so a light-based detector can measure their length and therefore their age. The machine spits out worms of the appropriate age into a single compartment of a dish with 1536 such compartments. A different chemical is added to each compartment (or well) and the effect of the chemical is noted. Thousands of these assays make up a chemical screen.
The worms are handy because they are small (a few millimeters long), fast-growing (in a nutritious liquid they can produce grandchildren in a single day), easily stored (freezing and thawing doesn’t bother them), and they have been well studied by biologists interested in simple behaviors.
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