Imaging of single light-responsive clock cells reveals fluctuating free-running periods.
Zebrafish tissues and cell lines contain circadian clocks that respond directly to light. Using fluorescence-activated cell sorting, we have isolated clonal cell lines that contain the reporter construct, zfperiod4-luciferase. Bioluminescent assays show that oscillations within cell populations are dampened in constant darkness. However, single-cell imaging reveals that individual cells continue to oscillate, but with widely distributed phases and marked stochastic fluctuations in free-running period. Because these cells are directly light responsive, we can easily follow phase shifts to single light pulses. Here we show that light acts to reset desynchronous cellular oscillations to a common phase, as well as stabilize the subsequent free-running period.
Carr
Amanda-Jayne F
AJ
University College London, Centre for Cell and Molecular Dynamics, Department of Anatomy and Developmental Biology, Rockefeller Building, 21 University Street, London WC1E 6DE, UK.
Whitmore
David
D
D000818:Animals; D001683:Biological Clocks; D002469:Cell Separation; D002940:Circadian Rhythm; D005347:Fibroblasts / Q000378:metabolism; D005434:Flow Cytometry; D008027:Light; D008156:Luciferases / Q000378:metabolism; D008856:Microscopy, Fluorescence / Q000379:methods*; D009687:Nuclear Proteins / Q000378:metabolism*; D009991:Oscillometry; D013997:Time Factors; D015027:Zebrafish
D009687:Nuclear Proteins; D008156:Luciferases