Over the past decade, her lab has probed several of these levels. In 2004, they reported that C. elegans sense precise oxygen concentrations in soil, which helps steer them toward their favorite meal: oxygen-consuming bacteria. Three years later, they investigated what neurons do with chemosensory information, finding that odor-sensing neurons can switch on other cells that control crawling and turning behaviors.
In the new study, Bendesky and Bargmann went one level deeper, investigating how genetic tweaks can change a worm's behavior in particular circumstances. To do their experiments, the researchers placed hundreds of different strains of C. elegans onto Petri dishes lined with a circular "lawn" of bacteria and calculated the rate at which worms left the lawn. "Lawn-leaving is something that occurs abruptly, in an all-or-none way. It's very striking," Bargmann says.
To find the genes that affect the behavior, they collaborated with HHMI investigator Leonid Kruglyak and his postdoc Matt Rockman to use a technique called quantitative trait locus analysis, they then analyzed the precise genetic make-up of each strain and correlated it with how frequently each strain left its lawn. In the end, the researchers could pinpoint particular genetic blips associated with moving away from a food source.
One of those blips crops up in a gene called npr-1, which had already been associated with foraging behaviors and immunity in the worm. The npr-1 variant is a sp
|Contact: Jim Keeley|
Howard Hughes Medical Institute