1. K. A. Hicks and D. R. Meeks-Wagner, Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA.
2. A. J. Millar, I. A. Carré, D. E. Somers, S. A. Kay, Department of Biology, NSF Center for Biological Timing, Gilmer Hall, University of Virginia, Charlottesville, VA 22903, USA.
3. M. Straume, Department of Medicine, NSF Center for Biological Timing, University of Virginia, Charlottesville, VA 22908, USA.