title: Cryptochrome-dependent and -independent circadian entrainment circuits in Drosophila.
abstract: Entrainment to environmental light/dark (LD) cycles is a central function of circadian clocks. In Drosophila, entrainment is achieved by Cryptochrome (CRY) and input from the visual system. During activation by brief light pulses, CRY triggers the degradation of TIMELESS and subsequent shift in circadian phase. This is less important for LD entrainment, leading to questions regarding light input circuits and mechanisms from the visual system. Recent studies show that different subsets of brain pacemaker clock neurons, the morning (M) and evening (E) oscillators, have distinct functions in light entrainment. However, the role of CRY in M and E oscillators for entrainment to LD cycles is unknown. Here, we address this question by selectively expressing CRY in different subsets of clock neurons in a cry-null (cry(0)) mutant background. We were able to rescue the light entrainment deficits of cry(0) mutants by expressing CRY in E oscillators but not in any other clock neurons. Par domain protein 1 molecular oscillations in the E, but not M, cells of cry(0) mutants still responded to the LD phase delay. This residual light response was stemming from the visual system because it disappeared when all external photoreceptors were ablated genetically. We concluded that the E oscillators are the targets of light input via CRY and the visual system and are required for normal light entrainment.
authors: Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan, yoshii@okayama-u.ac.jp.
authors: Taishi
authors: T
authors: Yoshii
authors: Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, University of Würzburg, Würzburg D-97074, Germany, and.
authors: Christiane
authors: C
authors: Hermann-Luibl
authors: Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan, Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, University of Würzburg, Würzburg D-97074, Germany, and.
authors: Christa
authors: C
authors: Kistenpfennig
authors: Max Planck Institute of Molecular Cell Biology and Genetics, D-01307 Dresden, Germany.
authors: Benjamin
authors: B
authors: Schmid
authors: Graduate School of Natural Science and Technology, Okayama University, Okayama 700-8530, Japan.
authors: Kenji
authors: K
authors: Tomioka
authors: Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, University of Würzburg, Würzburg D-97074, Germany, and.
authors: Charlotte
authors: C
authors: Helfrich-Förster
mesh_terms: D000818:Animals; D050976:Basic-Leucine Zipper Transcription Factors / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D056931:Cryptochromes / Q000235:genetics / Q000378:metabolism*; D004330:Drosophila; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D005123:Eye / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008027:Light; D008297:Male; D008822:Mice, Transgenic; D009043:Motor Activity / Q000235:genetics; D009154:Mutation / Q000235:genetics; D010812:Physical Stimulation; D012333:RNA, Messenger; D014795:Visual Pathways / Q000502:physiology*
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D056931:Cryptochromes; D029721:Drosophila Proteins; C109768:PDP1 protein, Drosophila; D012333:RNA, Messenger; C096445:tim protein, Drosophila; D049452:Green Fluorescent Proteins
keywords: Cryptochrome; Drosophila melanogaster; circadian clock; clock neurons; light entrainment