Phase-shifting the fruit fly clock without cryptochrome

Christa Kistenpfennig, Jay Hirsh, Taishi Yoshii, Charlotte Helfrich-Förster

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


The blue light photopigment cryptochrome (CRY) is thought to be the main circadian photoreceptor of Drosophila melanogaster. Nevertheless, entrainment to light-dark cycles is possible without functional CRY. Here, we monitored phase response curves of cry01 mutants and control flies to 1-hour 1000-lux light pulses. We found that cry01 mutants phase-shift their activity rhythm in the subjective early morning and late evening, although with reduced magnitude. This phase-shifting capability is sufficient for the slowed entrainment of the mutants, indicating that the eyes contribute to the clock's light sensitivity around dawn and dusk. With longer light pulses (3 hours and 6 hours), wild-type flies show greatly enhanced magnitude of phase shift, but CRY-less flies seem impaired in the ability to integrate duration of the light pulse in a wild-type manner: Only 6-hour light pulses at circadian time 21 significantly increased the magnitude of phase advances in cry01 mutants. At circadian time 15, the mutants exhibited phase advances instead of the expected delays. These complex results are discussed.

Original languageEnglish
Pages (from-to)117-125
Number of pages9
JournalJournal of biological rhythms
Issue number2
Publication statusPublished - Apr 2012


  • Drosophila melanogaster
  • cryptochrome
  • light pulses
  • locomotor activity

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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