A tiny worm has developed a compelling system for survival: It avoids trouble and sickness. A single genetic change in the tiny worm Caenorhabditis elegans compels some worms to stay away from harmful bacteria and others to eat the microorganisms [Science News]. While some researchers believe that the healthier worms also have some innate immunity to the bacteria, a new study shows definitively that a gene controls their behavior and keeps them from ingesting substances that will do them harm.
As reported in Science [subscription required], researchers first noted that a Hawaiian population of C. elegans had less resistance to harmful bacteria than the standard laboratory worms. A genetic study revealed that the Hawaiian worms have a different version of a gene called npr-1, which causes them to produce less of a protein that senses signals from neurons. When researchers tweaked the standard lab worms to have the same npr-1 mutation, those worms were also more susceptible to infection, indicating that the single gene was somehow responsible.
A genetic study of 
