Light-mediated TIM degradation within Drosophila pacemaker neurons (s-LNvs) is neither necessary nor sufficient for delay zone phase shifts

Neuron. 2010 May 13;66(3):378-85. doi: 10.1016/j.neuron.2010.04.015.


Circadian systems are entrained and phase shifted by light. In Drosophila, the model of light-mediated phase shifting begins with photon capture by CRYPTOCHROME (CRY) followed by rapid TIMELESS (TIM) degradation. In this study, we focused on phase delays and assayed TIM degradation within individual brain clock neurons in response to light pulses in the early night. Surprisingly, there was no detectable change in TIM staining intensity within the eight pacemaker s-LNvs. This indicates that TIM degradation within s-LNvs is not necessary for phase delays, and similar assays in other genotypes indicate that it is also not sufficient. In contrast, more dorsal circadian neurons appear light-sensitive in the early night. Because CRY is still necessary within the s-LNvs for phase shifting, the results challenge the canonical cell-autonomous molecular model and raise the question of how the pacemaker neuron transcription-translation clock is reset by light in the early night.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Clocks / physiology
  • Circadian Rhythm / physiology*
  • Drosophila
  • Drosophila Proteins / metabolism*
  • F-Box Proteins / metabolism
  • Fluorescent Antibody Technique
  • Light
  • Microscopy, Fluorescence
  • Neurons / metabolism*
  • Photoperiod
  • Time Factors


  • Drosophila Proteins
  • F-Box Proteins
  • JET protein, Drosophila
  • tim protein, Drosophila