Figure 3
A functional circadian oscillator in the lumbar spinal cord. (Upper left) A representative recording of the bioluminescence from the lumbar spinal cord of Per2::Luc mice. The bioluminescence was measured from cultures of spinal cord fragments (L4–5) for more than 5 days, as in Figure 1. (Next three panels) WT and PDK mice were entrained to a 12L:12D photoperiodic cycle for a week and then kept in constant darkness (DD). Two days after the lights were turned off, the mice were sacrificed by cervical dislocation at the indicated circadian time, and the spinal cord (lumbar 4–5 region) was quickly obtained. Real-time RT-PCR was performed to determine mRNA levels of Per1, Bmal1 and Rev-erbα. All mRNA levels were normalized to the Gapdh mRNA level and expressed as the mean±s.e.m. (n=4).L, light; D, dark; PDK, double knockout of Per1 and Per2 genes, WT, wild type.
