| Title | A rhodopsin in the brain functions in circadian photoentrainment in Drosophila |
| Author | Jinfei D. Ni, Lisa S. Baik, Todd C. Holmes & Craig Montell |
| Affiliation(s) | Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California 93106, USA
Center for Circadian Biology, University of California, San Diego, La Jolla, California 92093, USA
Department of Physiology and Biophysics, University of California, Irvine, Irvine, California 92697, USA |
| Published | Nature 545, 340–344 (18 May 2017) doi:10.1038/nature22325 |
| Keyword | |
| Snippet | |
| Abstract | Animals partition their daily activity rhythms through their internal circadian clocks, which are synchronized by oscillating day–night cycles of light. The fruitfly Drosophila melanogaster senses day–night cycles in part through rhodopsin-dependent light reception in the compound eye and photoreceptor cells in the Hofbauer–Buchner eyelet1. A more noteworthy light entrainment pathway is mediated by central pacemaker neurons in the brain. The Drosophila circadian clock is extremely sensitive to light. However, the only known light sensor in pacemaker neurons, the flavoprotein cryptochrome (Cry)2, 3, responds only to high levels of light in vitro4. These observations indicate that there is an additional light-sensing pathway in fly pacemaker neurons5. Here we describe a previously uncharacterized rhodopsin, Rh7, which contributes to circadian light entrainment by circadian pacemaker neurons in the brain. The pacemaker neurons respond to violet light, and this response depends on Rh7. Loss of either cry or rh7 caused minor defects in photoentrainment, whereas loss of both caused profound impairment. The circadian photoresponse to constant light was impaired in rh7 mutant flies, especially under dim light. The demonstration that Rh7 functions in circadian pacemaker neurons represents, to our knowledge, the first role for an opsin in the central brain. |
