Light-triggered mPer1 and mPer2 gene activity in mice without a working biological clock

Mice lacking mCry1 and mCry2 exhibit abolished cyclic expression of clock genes mPer1 and mPer2.

• Behavioral rhythms are absent in mice without mCry1 and mCry2.
• High levels of mPer1 and mPer2 mRNA are consistently present in these mice.
• The elimination of the biological clock is linked to the absence of both mCRY1 and mCRY2.
• Mice lacking these proteins can still respond to light stimuli that phase-shift the biological clock.

Simplified