Entrainment of Drosophila circadian clock to green and yellow light by Rh1, Rh5, Rh6 and CRY

Abstract

Light is one of the most important time cues for entrainment of the circadian clock. Drosophila circadian photoreception is mediated by cryptochrome in clock neurons and by rhodopsins in photic organs. We generated Rh5 mutants to elucidate circadian photoreception by rhodopsins. The Rh1, Rh5 and Rh6 mutants were combined with cry^b, and entrained to a 6-h delayed photoperiod. The cry^b, Rh1¹⁷, Rh5³ and Rh6¹ quadruple mutant became entrained by white light. In contrast, reentrainment to green and yellow light was abolished in the cry^b, Rh1¹⁷, Rh5³ and Rh6¹ quadruple mutant, and remarkably slowed in the cry^b, Rh1¹⁷ and Rh6¹ triple mutant. These results suggest that cry, Rh1, Rh5 and Rh6 are essential for circadian photoentrainment to green and yellow light.