The circadian clock plays a pivotal role in modulating physiological processes and has been implicated, either directly or indirectly, in a range of pathological states including cancer. Here we investigate how the circadian clock is entrained by external cues such as light. Working with zebrafish cell lines and combining light pulse experiments with simulation efforts focused on the role of synchronization effects, we find that even very modest doses of light exposure are sufficient to trigger some entrainment, whereby a higher light intensity or duration correlates with strength of the circadian signal. Moreover, we observe in the simulations that stochastic effects may be considered an essential feature of the circadian clock in order to explain the circadian signal decay in prolonged darkness, as well as light initiated resynchronization as a strong component of entrainment.
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http://dx.doi.org/10.1155/2015/254979 | DOI Listing |
Chronobiol Int
January 2025
Facultade de Física, Departamento de Física Aplicada and iMATUS, Universidade de Santiago de Compostela, Santiago de Compostela, Spain.
We analyze the results to question 2 (individual preferences for cancelling or keeping the current clock regulations) from the 2018 Public Consultation on summertime arrangements (DST) conducted by the European Commission. We reveal correlations in the shares of population for cancelling the regulations and the winter sunrise time (SRW) [ = 0.177; = 0.
View Article and Find Full Text PDFMitochondria are key regulators of metabolism and ATP supply in skeletal muscle, while circadian rhythms influence many physiological processes. However, whether mitochondrial function is intrinsically regulated in a circadian manner in mouse skeletal muscle is inadequately understood. Accordingly, we measured post-absorptive transcript abundance of markers of mitochondrial biogenesis, dynamics, and metabolism (extensor digitorum longus [EDL], soleus, gastrocnemius), protein abundance of electron transport chain complexes (EDL and soleus), enzymatic activity of SDH (tibialis anterior and plantaris), and maximum uncoupled respiration (tibialis anterior) in different skeletal muscles from female C57BL/6NJ mice at four zeitgeber times (ZT), ZT 1, 7, 13, and 19.
View Article and Find Full Text PDFVitam Horm
January 2025
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina; Centro de Estudios Biomédicos Básicos, Aplicados y Desarrollo (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina. Electronic address:
Light is the most reliable environmental cue allowing animals to breed successfully when conditions are optimal. In seasonal breeders, photoperiod (length of daylight) information is sensed by the eyes and transmitted to the suprachiasmatic nucleus, the master clock region located in the hypothalamus. This structure has a 24-h firing rhythm involving a cycle of clock protein synthesis and degradation, and provides the timing to synchronize the synthesis and release of melatonin, the chemical signal that transduces the photoperiod information.
View Article and Find Full Text PDFHandb Clin Neurol
January 2025
Escola de Educação Física, Fisioterapia e Terapia Ocupacional, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil; Faculty of Health Sciences, Universidad Autónoma de Chile, Providencia, Chile. Electronic address:
It is well established that sleep promotes health and welfare. Literature data suggests that sleep is a recurrent resting state that performs multiple biological functions, such as memory consolidation and regulation of glucose, lipid metabolism, energy metabolism, eating behavior, and blood pressure, besides, regulating the immune system. These immunological functions depend on regular sleep and circadian rhythms, as both impact the magnitude of immune responses.
View Article and Find Full Text PDFHandb Clin Neurol
January 2025
Sleep Medicine Center, Department of Neurology, Villa Serena Hospital, Città S. Angelo, Pescara, Italy; Villaserena Research Foundation, Città S. Angelo, Pescara, Italy.
Advanced sleep phase (ASP) is seldom brought to medical attention because many individuals easily adapt to their early chronotype, especially if it emerges before the age of 30 and is present in a first-degree relative. In this case, the disorder is considered familial (FASP) and is mostly discovered coincidentally in the presence of other sleep disorders, mainly obstructive sleep apnea syndrome (OSAS). The prevalence of FASP is currently estimated to be between 0.
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