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Science 300 (5625): 1534-1535

Copyright © 2003 by the American Association for the Advancement of Science

Circadian Rhythms: In the Loop at Last

Russell N. Van Gelder,1,2* Erik D. Herzog,4 William J. Schwartz,5 Paul H. Taghert3

Abstract: The basic molecular mechanisms underlying circadian oscillators follow the same general plan across the phylogenetic spectrum: oscillating feedback loops in which clock gene products negatively regulate their own expression. The circadian clocks of animals involve at least two interacting feedback loops. This Viewpoint compares and contrasts the circadian clocks of mammals and of Drosophila, emphasizing how different players are used to create the same basic script. Both the general script and the specific details of the murine and Drosophila circadian pathways are available at Science's Signal Transduction Knowledge Environment Connections Maps.

1 Department of Ophthalmology and Visual Sciences, Washington University, St. Louis, MO 63110, USA.
2 Department of Molecular Biology and Pharmacology, Washington University, St. Louis, MO 63110, USA.
3 Department of Anatomy and Neurobiology, School of Medicine, Washington University, St. Louis, MO 63110, USA.
4 Department of Biology, Washington University, St. Louis, MO 63110, USA.
5 Department of Neurology, University of Massachusetts Medical School, Worcester, MA 01655, USA.

* To whom correspondence should be addressed. E-mail: vangelder{at}

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