title: The circadian Clock mutant mouse: impaired masking response to light.
abstract: Synchronization of an internal clock (entrainment) and a direct response to light (masking) are complementary ways of restricting activity of an animal to day or night. The protein CLOCK has an important role in the oscillatory mechanism of mammalian pacemakers. Our data show that it is also involved in masking responses. Mice with the Clock/Clock mutation reduced their wheel running less than wildtypes when given 1-h light pulses of light (2-1,600 lx) in the night. With dimmer lights (<2 lx), there were no significant differences between mutant and wildtype mice. Impaired masking responses to light in Clock/Clock mice were confirmed in tests with ultradian light-dark cycles (3.5:3.5 h and 1:1 h). Tests with pulses of light longer than 1 h revealed that, although the mutants responded more slowly to light, they sustained the suppression of activity over the course of the 3-h tests better than wildtypes.
authors.affiliation: Department of Animal Physiology, Biological Institute, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany.
authors.forename: Uwe
authors.initials: U
authors.lastname: Redlin
authors.forename: Samer
authors.initials: S
authors.lastname: Hattar
authors.forename: N
authors.initials: N
authors.lastname: Mrosovsky
mesh_terms: D000204:Activity Cycles / Q000502:physiology / Q000528:radiation effects; D000818:Animals; D056926:CLOCK Proteins; D002940:Circadian Rhythm / Q000502:physiology* / Q000528:radiation effects; D008027:Light; D055537:Light Signal Transduction / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D009043:Motor Activity / Q000502:physiology* / Q000528:radiation effects; D010470:Perceptual Masking / Q000502:physiology*; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*
chemical_list: D015534:Trans-Activators; D056926:CLOCK Proteins; C538944:Clock protein, mouse