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TRIPARTITE OSCILLATORS. “The mammalian circadian system is organized around three major physiological components: an input pathway by which environmental cues (most importantly light) are transmitted to the central or 'master' pacemaker, the central pacemaker itself, and finally a set of output pathways by which the central pacemaker regulates circadian rhythms throughout the body.” https://lnkd.in/d3X7KfC View in LinkedIn

KEY CLOCK GENES. “Core clock components are defined as genes with protein products that are essential for the generation and regulation of circadian rhythms. Ablation of any of the core clock genes, Clock or Bmal1, Per1 or Per2, or Cry1 or Cry2, disrupts circadian physiology.” https://lnkd.in/dH6Ha79 View in LinkedIn

DEEPLY INGRAINED. “The circadian system is involved in maintaining energy homeostasis. Approximately 10% of the mammalian transcriptome display circadian oscillations. Among the rhythmic genes identified, many have a specific role in coordinating nutrient metabolism. For example, glucose transporters and the glucagon receptor, as well as multiple enzymes involved in the metabolism of sugars and the biosynthesis of cholesterols, are rhythmically expressed.” https://lnkd.in/dH6Ha79 View in LinkedIn

CLOCK MECHANISM. “The circadian clock is driven by an autoregulatory feedback loop. CLOCK and BMAL1 form a heterodimer that induces expression of Per and Cry through E-box enhancers. PER and CRY proteins accumulate in the cytoplasm throughout the circadian day. CK GENES. “Upon reaching critical levels, PER and CRY form a complex that translocates back to the nucleus to associate with CLOCK and BMAL1 and repress their own transcription. This process takes approximately 24 hours to complete a full cycle.” https://lnkd.in/dH6Ha79 View in LinkedIn

MAGNIFICENT CLOCKS. “Across phyla, all circadian clocks share several fundamental properties: they are synchronized (entrained) each day to external cues, they are self-sustained and produce oscillations that persist in the absence of any external cues, they are temperature compensated such that temperature changes in the physiological range do not alter their endogenous period, and of particular relevance to this review, they are cell-autonomous and genetically-determined.” https://lnkd.in/d3X7KfC View in LinkedIn

CLOCK TRANSCRIPTION. “In mammals, the mechanism of the circadian clock is cell autonomous and arises from an autoregulatory negative feedback transcriptional network. At the core of this clock network are the transcriptional activators, CLOCK (and its paralog, NPAS2) and BMAL1.” https://lnkd.in/dBQ96E6 View in LinkedIn

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UBIQUITOUS CLOCKS. “The discovery of ‘clock genes’ led to the realization that the capacity for circadian gene expression is widespread throughout the body. Using circadian gene reporter methods, one can demonstrate that most peripheral organs and tissues can express circadian oscillations in isolation, yet still receive and may require input from the SCN in vivo. The cell autonomous clock has been found to be ubiquitous, and almost every cell in the body contains a circadian clock.” (SCN = Suprachiasmatic nucleus). https://lnkd.in/dBQ96E6 View in LinkedIn

LIGHT NIGHTS AND LEARNING. “Diurnal Nile Grass rats (Arvicanthis niloticus) exposed to light at night have impaired learning and memory and increase depressive-like responses compared with rats maintained in dark nights. Furthermore, exposure to light at night affects foraging and predation and migration in multiple species.” https://lnkd.in/dH6Ha79 View in LinkedIn

STREET LIGHT IMPACT. “Overall, these results indicate that exposure to levels of nighttime lighting commonly experienced in urban settings can affect the circadian system.” https://lnkd.in/dH6Ha79 View in LinkedIn