Role of a blue-light sensor in mice for regulating daily biological rhythms

Mice lacking the cryptochrome 2 gene had an intrinsic circadian period about 1 hour longer than normal.

• Mutant mice showed lower sensitivity to light-induced activation of a specific gene related to the circadian clock.
• Normal circadian oscillations of certain messenger RNA levels were observed in the suprachiasmatic nucleus of mutant mice.
• High-amplitude phase shifts were noted in the mutants in response to light pulses at a specific circadian time.
• Findings support the idea that cryptochrome 2 may influence circadian responses in mammals.

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