Caltech researchers find dual-use sexual attraction and population-control chemicals in...( PASADENA Calif.--Organisms ranging f...)

PASADENA, Calif.--Organisms ranging from humans to plants to the lowliest bacterium use molecules to communicate. Some chemicals trigger the various stages of an organism's development, and still others are used to attract members of the opposite sex. Researchers at the California Institute of Technology have now found a rare kind of signaling molecule in the nematode worm Caenorhabditis elegans that serves a dual purpose, working as both a population-control mechanism and a sexual attractant.

The discovery, published online July 23 in the journal Nature, could lead to new ways to control parasitic nematodes, which affect the health of more than a billion people and each year cause billions of dollars in crop damage.

Caenorhabditis elegans worms have long been a favorite model organism among developmental biologists, in part because of their small size (1 mm long), simple nervous system, and ease of care. The normally soil-dwelling worms are almost always hermaphrodites--females that are capable of making sperm, with which they can fertilize their own eggs. About one in every 1000 worms is a true male.

Researchers studying C. elegans had long noted that hermaphroditic worms, left to wander about in a culture plate, will secrete a chemical that strongly attracts males. When males are exposed to the chemical, dubbed "worm sweat" by C. elegans researchers, "males will act as if their desired mate is near, and start blindly feeling around to locate it," says molecular geneticist Paul W. Sternberg, the Thomas Hunt Morgan Professor of Biology at Caltech and an investigator with the Howard Hughes Medical Institute.

Jagan Srinivasan, a postdoctoral research scholar at Caltech, Sternberg, and his colleagues at the University of Florida, the United States Department of Agriculture, and Cornell University, assayed and analyzed worm sweat and found that it consisted of a blend of three related chemicals, cal
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