Comment on "Circadian rhythms in the absence of the clock gene Bmal1"

To better understand these surprising results, we reanalyzed the associated data. We were unable to reproduce the original findings, nor could we identify reliably cycling genes. We conclude that there is insufficient evidence to support circadian transcriptional rhythms in the absence of Bmal1. Recently, Ray et al. (1) reported transcriptional rhythmicity in mouse tissues lacking BMAL1. BMAL1 is a core component of the circadian molecular oscillator (2) whose deletion is associated with loss of physiological and molecular rhythms (3).