highly significantp < 0.001
Comparison by 2-way ANOVA of circadian periods in PER1 and PER2 single-mutant mice, with and without Tau ( Per1- null n = 14, 13; Per2- null n = 10, 12), revealed a highly significant effect of Tau (F 1,80 = 1909, p < 0.001) but not of Per genotype (F 2,80 = 0.099, p = 0.91).