Cryptochrome-dependent and -independent circadian entrainment circuits in Drosophila

Taishi Yoshii, Christiane Hermann-Luibl, Christa Kistenpfennig, Benjamin Schmid, Kenji Tomioka, Charlotte Helfrich-Förster

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


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 (cry0) mutant background. We were able to rescue the light entrainment deficits of cry0 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 cry0 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.

Original languageEnglish
Pages (from-to)6131-6141
Number of pages11
JournalJournal of Neuroscience
Issue number15
Publication statusPublished - Apr 15 2015


  • Circadian clock
  • Clock neurons
  • Cryptochrome
  • Drosophila melanogaster
  • Light entrainment

ASJC Scopus subject areas

  • Neuroscience(all)


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