... Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan 2. PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama, 332-0012, Japan 3. Division of Sustainable ... utilize flavin as light-absorbing co-factors, are the primary circadian photoreceptors.4 Circadian rhythms are oscillations in the behav-iour and biochemical reactions of organisms that occur ... Per2, and Per3, and the transcrip-tional activator genes, Clock and Bmal1 (Brain and Muscle aryl hydrocarbon receptor nuclear translocator Int. J. Med. Sci. 2008, 5 324 Figure 3 (A) ...