Study Schematic (IMAGE) RIKEN Caption This study established an efficient method for conducting gene-rescue experiments in mutant mice. Applying the method to knock in a series of CRY1 mutants into Cry1-/-:Cry2-/- mice, researchers discovered that multisite phosphorylation around the flexible loop domains of CRY1 determine the period length of the mammalian circadian clock in vivo. Credit RIKEN Usage Restrictions credit RIKEN National Science Institute License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.