"We hypothesized if the photo sensory domain of WC-1 was removed, all light- regulated processes, including the circadian clock, would be blind," said Liu.

The researchers tested this hypothesis by creating an organism that lacked WC-1 putative photo sensory domain. Liu and his collaborators demonstrated that WC-1, like all known photoreceptors, is associated with a photo pigment, the molecule that is sensitive to light.

"As we predicted, this mutant organism was literally blind to light. The circadian clock was no longer synchronized by light and the light-regulated genes were not turned on after light treatment, which affected many physiological processes," Liu said.

"All light responses were interrupted in this mutant, including the growth of mold and the production of spores," said Liu, who also was co-author of a second study published on this week's Science Web site about the role of WC-1 in mediating light input to the circadian clock.

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Contact: Amy Shields
Amy.Shields@UTSouthwestern.edu
214-648-3404
UT Southwestern Medical Center
4-Jul-2002