A serum shock induces circadian gene expression in mammalian tissue culture cells
A. Balsalobre, F. Damiola, U. Schibler

The work of Balsalobre and colleagues came at a time when the general belief of the scientific community was that the suprachiasmatic nucleus (SCN) in the hypothalamus was the one and only center responsible for generating circadian rhythms of physiology..

Restricted feeding uncouples circadian oscillators in peripheral tissues from the central pacemaker in the suprachiasmatic nucleus
F. Damiola, N. Le Minh, N. Preitner, B. Kornmann, F. Fleury-Olela, U. Schibler

The work of Damiola and colleagues is a landmark study in the understanding of peripheral circadian clocks. What was known at the time was that the phase of peripheral clocks is synchronized via chemical cues produced by the suprachiasmatic nucleus (SCN) of the hypothalamus, which serves as a master pacemaker for the whole organism. The SCN receives input from the optic nerves delivering information of the existence of light...

A clock shock: mouse CLOCK is not required for circadian oscillator function
J. P. Debruyne, E. Noton, C. M. Lambert, E. S. Maywood, D. R. Weaver, S. M. Reppert

The study by Debruyne and colleagues was able to shake the whole field of circadian biology for a while by challenging the role of the first gene related to circadian rhythms in mammals. As the title suggests, this was a real shock to the understanding at the time since there were numerous studies based on a mutant of the Clock gene...

Light activates the adrenal gland: timing of gene expression and glucocorticoid release
A. Ishida, T. Mutoh, T. Ueyama, H. Bando, S. Masubuchi, D. Nakahara, G. Tsujimoto, H. Okamura

The early finding that lesion of the suprachiasmatic nucleus (SCN) in the hypothalamus abolishes the behavioral rhythms of animals revealed the SCN as the master regulator of time information. The SCN is responsible for synchronizing physiology to environmental light-dark cycles...

Clock mutants of Drosophila melanogasterm
R. J. Konopka, S. Benzer

The work of Konopka and Benzer is a landmark study that has been cited almost 900 times so far. Ron Konopka, while a graduate student in Benzer’s laboratory, performed phenotypebased screening of mutagen-exposed flies as early as 1971 and established the modern era of the field of circadian rhythms...

Regulation of CLOCK and MOP4 by nuclear hormone receptors in the vasculature: a humoral mechanism to reset a peripheral clock
P. McNamara, S. B. Seo, R. D. Rudic, A. Sehgal, D. Chakravarti, G. A. FitzGerald

The study of McNamara and colleagues was the first to investigate the circadian clock at the molecular level in a tissue/cell type relevant to the cardiovascular system. Even though diurnal variation in the occurrence of cardiovascular events, such as myocardial infarction and stroke, was well described, no study previous to this one had shown that the circadian clock resides in cardiovascular system tissue...

Circadian variation of blood-pressure
M. W. Millar-Craig, C. N. Bishop, E. B. Raftery

Millar-Craig and colleagues were the first to recognize circadian rhythm in blood pressure. Before their study, there was confusion as to how blood pressure changes over the course of the day...

Coordinated transcription of key pathways in the mouse by the circadian clock
S. Panda, M. P. Antoch, B. H. Miller, A. I. Su, A. B. Schook, M. Straume, P. G. Schultz, S. A. Kay, J. S. Takahashi, J. B. Hogenesch

The study by Panda and colleagues was another landmark study that led to many future studies exploring the relationship between metabolism and the circadian clock. Key findings from this study contributed significantly to the current understanding of the role of circadian clocks...

The orphan nuclear receptor REV-ERBalpha controls circadian transcription within the positive limb of the mammalian circadian oscillator
N. Preitner, F. Damiola, L. Lopez-Molina, J. Zakany, D. Duboule, U. Albrecht, U. Schibler

Preitner and colleagues revealed the orphan nuclear receptor Rev-erb a as a member of the circadian clock machinery as early as 2002. It would take another five years before scientists from the University of Pennsylvania would shed more light on the role of Rev-erb a in the circadian clock...

Extensive and divergent circadian gene expression in liver and heart
K. F. Storch, O. Lipan, I. Leykin, N. Viswanathan, F. C. Davis, W. H. Wong, C. J. Weitz

The study of Storch and colleagues is a systems biology approach to the role of the circadian clock in peripheral tissues. The authors compare the circadian expression of genes in two peripheral tissues, liver and heart...