Circadian clocks refer to the circadian timing system, which generates and orchestrates circadian rhythms.
They are involved in the transport of eye pigments [ 11], lipid-modified peptide chemoattractants [ 12], glutathione-conjugated organic anions [ 13], and possibly 20-hydroxyecdysone to orchestrate circadian transcription of clock genes [ 14].
The lengthened free-running circadian period tau in HAB mice indicates that the derangement of the circadian behavior is likely due to a dysfunction of the endogenous circadian rhythm in these animals, most likely originating from a compromise in the molecular circadian machinery orchestrating the circadian rhythm under DD conditions.
Mammals have a central pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN) that orchestrates circadian rhythms for the whole body.
Based on these observations, our data imply that rod and cone photoreceptors interact with each other via gap junctions to coordinate circadian clocks in the individual photoreceptors, and orchestrate circadian physiology such as melatonin release.
In addition, sex hormone receptors are present in the suprachiasmatic nucleus (SCN) [ 41], the key biologic clock in the brain that orchestrates circadian biological rhythms, such as the rhythms of hormones, body temperature, sleep and mood.
The hierarchical model of the circadian system that has emerged is that of the central SCN circadian clock integrating time cue information and conveying neural and blood-borne signals to orchestrate the circadian oscillators in extra-SCN brain sites as well as in the periphery [ 8– 11].
To summarise, a number of candidate cells may orchestrate the circadian oscillation in IL-6 secretion.
The suprachiasmatic nucleus is believed to orchestrate the circadian clock in peripheral tissues through hormonal and/or neuronal regulation (Balsalobre et al. 2000, Terazono et al. 2003, Yoo et al. 2004).
These studies include determining the direct and indirect targets of the light-controlled TFs, and the interplay of TFs in orchestrating the light and circadian response.
