Figure 1.

Bioluminescence spectra of Bmal1–GR and Bmal1–RED cell lines. Cells were incubated with 100 nM DEX for 18 h to synchronize circadian expression of the luciferases. Around the expected peak time of reporter gene expression, the Bmal1–GR (1.9 × 10⁷ cells) and Bmal1–RED (1.7 × 10⁷ cells) cells were trypsinized and collected from culture dishes. Cells were suspended in 250 μl of the luciferin medium. Their bioluminescence spectra were measured using an AB1850 spectrophotometer (ATTO, Tokyo, Japan). The wavelengths of the light emitted (Bmal1–GR, λmax = 556 nm; Bmal1–RED, λmax = 633 nm) were almost equal to those previously reported in cell extracts.