Aronin, NeilSagar, Stephen M.Sharp, Frank R.Schwartz, William J.2022-08-232022-08-231990-08-012009-04-02<p>Proc Natl Acad Sci U S A. 1990 Aug;87(15):5959-62.</p>0027-8424 (Print)2116012https://hdl.handle.net/20.500.14038/39003Mammalian circadian rhythmicity is endogenously generated by a pacemaker in the suprachiasmatic nuclei and precisely entrained to the 24-hr day/night cycle by periodic environmental light cues. We show that light alters the immunoreactive levels of a transcriptional regulatory protein, Fos, in the suprachiasmatic nuclei of albino rats. Photic regulation of Fos immunoreactivity does not occur in other retino-recipient brain areas except for the intergeniculate leaflet, which appears to be involved in mediating some of the complex effects of light on expressed circadian rhythms. Our results point to a promising new functional marker for the cellular effects of light and suggest that the expression of Fos or a related nuclear protein may be part of the mechanism for photic entrainment of the circadian clock to environmental light/dark cycles.en-USAnimalsCell NucleusCircadian RhythmDNA-Binding ProteinsDarknessGene ExpressionHela CellsHumansImmune SeraImmunohistochemistry*LightMaleProto-Oncogene ProteinsProto-Oncogene Proteins c-fosRatsRats, Inbred StrainsSuprachiasmatic NucleusLife SciencesMedicine and Health SciencesJournal Articlehttps://escholarship.umassmed.edu/oapubs/1829808595oapubs/1829