Green-sensitive opsin is the photoreceptor for photic entrainment of an insect circadian clock

作者：Sayaka Komada, Yuichi Kamae, Mitsumasa Koyanagi, Kousuke Tatewaki, Ehab Hassaneen, Asm Saifullah, Taishi Yoshii, Akihisa Terakita, Kenji Tomioka · 发表于：Zoological Letters · 年份：2015 · DOI：10.1186/s40851-015-0011-6 · 被引用次数：41 · 研究领域：Circadian rhythm and melatonin、Neurobiology and Insect Physiology Research、Physiological and biochemical adaptations

INTRODUCTION: Entrainment to light cycle is a prerequisite for circadian rhythms to set daily physiological events to occur at an appropriate time of day. In hemimetabolous insects, the photoreceptor molecule for photic entrainment is still unknown. Since the compound eyes are the only circadian photoreceptor in the cricket Gryllus bimaculatus, we have investigated the role of three opsin genes expressed there, opsin-Ultraviolet (opUV), opsin-Blue (opB), and opsin-Long Wave (opLW) encoding a green-sensitive opsin in photic entrainment. RESULTS: A daily rhythm was detected in mRNA expressions of opB and opLW but not of opUV gene. When photic entrainment of circadian locomotor rhythms was tested after injection of double-stranded RNA (dsRNA) of three opsin genes, no noticeable effects were found in opUV RNAi and opB RNAi crickets. In opLW RNAi crickets, however, some crickets lost photic entrainability and the remaining crickets re-entrained with significantly longer transient cycles to a phase-advanced light-dark cycle as compared to control crickets. Crickets often lost entrainability when treated doubly with dsRNAs of two opsin genes including opLW. CONCLUSION: These results show that green-sensitive OpLW is the major circadian photoreceptor molecule for photic entrainment of locomotor rhythms in the cricket G. bimaculatus. Our finding will lead to further investigation of the photic entrainment mechanism at molecular and cellular levels, which still remains largely unknown.