Circadian Photoreception in Humans and Mice

The induction of c-fos in the SCN as a function of genotype and irradiance. Mice were exposed to light pulses of indicated intensity during the night phase, and the level of c-fos induction was determined by in situ hybridization. Each light intensity induced c-fos in both wild-type and rd mutant mice, whereas Cry1^-/-Cry2^-/- significantly reduced c-fos induction under both dim and bright light. Significantly, c-fos induction was severely reduced in rd/rdCry1^-/-Cry2^-/- mice under all light conditions. From reference (50) .