Light acts directly on organs and cells in culture to set the vertebrate circadian clock

Nature. 2000 Mar 2;404(6773):87-91. doi: 10.1038/35003589.


The expression of clock genes in vertebrates is widespread and not restricted to classical clock structures. The expression of the Clock gene in zebrafish shows a strong circadian oscillation in many tissues in vivo and in culture, showing that endogenous oscillators exist in peripheral organs. A defining feature of circadian clocks is that they can be set or entrained to local time, usually by the environmental light-dark cycle. An important question is whether peripheral oscillators are entrained to local time by signals from central pacemakers such as the eyes or are themselves directly light-responsive. Here we show that the peripheral organ clocks of zebrafish are set by light-dark cycles in culture. We also show that a zebrafish-derived cell line contains a circadian oscillator, which is also directly light entrained.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Clocks* / genetics
  • Biological Clocks* / radiation effects
  • CLOCK Proteins
  • Cell Line
  • Circadian Rhythm* / genetics
  • Circadian Rhythm* / radiation effects
  • Heart / physiology
  • Heart / radiation effects
  • Kidney / physiology
  • Kidney / radiation effects
  • Light*
  • Organ Culture Techniques
  • Temperature
  • Trans-Activators / genetics
  • Zebrafish


  • Trans-Activators
  • CLOCK Proteins