Temporal organisation of biology: circadian, circatidal, circalunar, circannual rhythms; their molecular bases (clock genes), entrainment, and medical consequences. 2017 Nobel to Hall, Rosbash, Young for molecular circadian mechanism.
chronobiology
Circadian rhythm
Endogenous ~24 h biological oscillation, persisting in constant conditions (free-running period τ ≈ 24.2 h in humans). Entrained by…
Clock genes and TTFL
Transcription–translation feedback loop: CLOCK:BMAL1 heterodimer drives expression of Per, Cry; PER:CRY complexes feed back to inhibit…
Suprachiasmatic nucleus (SCN)
Hypothalamic nucleus above the optic chiasm containing ~20,000 neurons; the master circadian pacemaker of mammals. Directly innervated by…
Melatonin signalling
N-acetyl-5-methoxytryptamine released by the pineal gland at night under SCN control. Signals darkness; feeds back onto SCN (MT1) and…
Entrainment
Phase and period alignment of endogenous oscillator to an external zeitgeber. Phase-response curve Δφ(φ) quantifies advance/delay as a…
Jet lag and shift-work disorder
Acute misalignment between internal circadian phase and external time/activity. Jet lag resolves at ~1 day per time-zone; chronic…
Peripheral clocks
Cell-autonomous molecular clocks in nearly every tissue (liver, muscle, adipose, gut) entrained by SCN output and local cues (food timing,…
Chronopharmacology
Time-of-day dependence of drug efficacy and toxicity. Examples: statins more effective evening (HMG-CoA peaks at night), chemotherapy…