Worms take the sniff test to reveal sex difference...(ssor of Biomedical Genetics. We think th...)

C. elegans is a one-millimeter-long critter that provides a unique window onto the human brain. Back in 1998, the worm gained fame as the first multi-celled organism to have its genome sequenced. About half of the organisms approximate 22,000 genes have direct counterparts in people, but its nervous system is far simpler. Indeed, researchers have identified and named every one of the male worms 383 neurons, while barely scratching the surface of the hundreds of billions of neurons in the human brain.

Portman and Lee are using the organism to try to work out some of the fundamental rules that govern the nervous systems not only of worms but also people.

The key to neurons is how they talk to each other. In a human brain, there are trillions of such connections. In a worm, there are thousands still a considerable challenge to understand, but its much more do-able, and its a stepping-stone to understanding how the human brain works. The architecture is much simpler to try to understand, Portman said.

The team is focusing on sex differences in the nerve cells of the critters, which come in two sexes: males, and hermaphrodites, basically females that are able to reproduce on their own because they can produce both egg and sperm. The two sexes share a core nervous system made up of 294 neurons that are exactly the same; hermaphrodites have eight additional neurons, while males have 87 additional neurons. (The male devotes a large portion of its nervous system to its ability to copulate, but thats another story altogether.)

The team ran hundreds of experiments in which worms in Petri dishes were given 45 minutes to crawl toward one of two scents. One difference stood out: Hermaphrodites more often
'/>"/>