Figure 4. Single cell rhythms in WT Per2^Luc culture.

A) The intensity of bioluminescence (in arbitrary units) of the field of view captured by the CCD camera over days in vitro, as described in the Methods, which was used to determine locations of 630 ROIs in a hepatocyte collagen gel sandwich culture. The average local density is 19 ROIs/mm². B) Periods of the rhythmic ROIs (AWT estimate during DIV 3 to 5), with mean 22.8 h and standard deviation 0.5 h. C) PER2::LUC bioluminescence traces for the rhythmic ROIs, with trend and noise removed by discrete wavelet transform.