1. M. P. Myers, K. Wager-Smith, C. S. Wesley, M. W. Young, Howard Hughes Medical Institute, National Science Foundation Science and Technology Center for Biological Timing, and Laboratory of Genetics, Rockefeller University, New York, NY 10021, USA.
2. A. Sehgal, Department of Neuroscience and Center for Sleep and Respiratory Neurobiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.