A new study identifies a cell-autonomous two-hour clock in diverse types of mammalian cells in culture. The two-hour oscillations depend on negative feedback of a gene product, Hes1, on transcription of its own gene—a regulatory mechanism that is identical to the circadian clock. Although a similar two-hour clock is required for vertebrate somitogenesis, the physiological role of the two-hour clock in cells remains unclear.
- Michael N. Nitabach
- Justin Blau
