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Dialogues in Clinical Neuroscience Dec 2012Environmental light synchronizes the primary mammalian biological clock in the suprachiasmatic nuclei, as well as many peripheral clocks in tissues and cells, to the... (Review)
Review
Environmental light synchronizes the primary mammalian biological clock in the suprachiasmatic nuclei, as well as many peripheral clocks in tissues and cells, to the solar 24-hour day. Light is the strongest synchronizing agent (zeitgeber) for the circadian system, and therefore keeps most biological and psychological rhythms internally synchronized, which is important for optimum function. Circadian sleep-wake disruptions and chronic circadian misalignment, as often observed in psychiatric and neurodegenerative illness, can be treated with light therapy. The beneficial effect on circadian synchronization, sleep quality, mood, and cognitive performance depends on timing, intensity, and spectral composition of light exposure. Tailoring and optimizing indoor lighting conditions may be an approach to improve wellbeing, alertness, and cognitive performance and, in the long term, producing health benefits.
Topics: Affect; Animals; Biological Clocks; Circadian Rhythm; Humans; Light
PubMed: 23393421
DOI: 10.31887/DCNS.2012.14.4/mmuench -
Science Advances Mar 2023An overview on the molecular and metabolic mechanisms behind individual cell differences in developmental timing in the segmentation clock and the central nervous system. (Review)
Review
An overview on the molecular and metabolic mechanisms behind individual cell differences in developmental timing in the segmentation clock and the central nervous system.
Topics: Biological Clocks; Gene Expression Regulation, Developmental
PubMed: 36888707
DOI: 10.1126/sciadv.adh1849 -
Scientific Reports Apr 2023Estimating time of death is one of the most important problems in forensics. Here, we evaluated the applicability, limitations and reliability of the developed...
Estimating time of death is one of the most important problems in forensics. Here, we evaluated the applicability, limitations and reliability of the developed biological clock-based method. We analyzed the expression of the clock genes, BMAL1 and NR1D1, in 318 dead hearts with defined time of death by real-time RT-PCR. For estimating the time of death, we chose two parameters, the NR1D1/BMAL1 ratio and BMAL1/NR1D1 ratio for morning and evening deaths, respectively. The NR1D1/BMAL1 ratio was significantly higher in morning deaths and the BMAL1/NR1D1 ratio was significantly higher in evening deaths. Sex, age, postmortem interval, and most causes of death had no significant effect on the two parameters, except for infants and the elderly, and severe brain injury. Although our method may not work in all cases, our method is useful for forensic practice in that it complements classical methods that are strongly influenced by the environment in which the corpse is placed. However, this method should be applied with caution in infants, the elderly, and patients with severe brain injury.
Topics: Infant; Humans; Aged; ARNTL Transcription Factors; Reproducibility of Results; Biological Clocks; Autopsy; Brain Injuries; Circadian Rhythm
PubMed: 37055510
DOI: 10.1038/s41598-023-33328-3 -
Biomedicine & Pharmacotherapy =... Oct 2023Diabetic retinopathy (DR) is a severe microvascular complication of diabetes mellitus and a major cause of blindness in young adults. Multiple potential factors... (Review)
Review
Diabetic retinopathy (DR) is a severe microvascular complication of diabetes mellitus and a major cause of blindness in young adults. Multiple potential factors influence DR; however, the exact mechanisms are poorly understood. Advanced treatments for DR, including laser therapy, vitrectomy, and intraocular drug injections, slow the disease's progression but fail to cure or reverse visual impairment. Therefore, additional effective methods to prevent and treat DR are required. The biological clock plays a crucial role in maintaining balance in the circadian rhythm of the body. Poor lifestyle habits, such as irregular routines and high-fat diets, may disrupt central and limbic circadian rhythms. Disrupted circadian rhythms can result in altered glucose metabolism and obesity. Misaligned central and peripheral clocks lead to a disorder of the rhythm of glucose metabolism, and chronically high sugar levels lead to the development of DR. We observed a disturbance in clock function in patients with diabetes, and a misaligned clock could accelerate the development of DR. In the current study, we examine the relationship between circadian rhythm disorders, diabetes, and DR. We conclude that: 1) abnormal function of the central clock and peripheral clock leads to abnormal glucose metabolism, further causing DR and 2) diabetes causes abnormal circadian rhythms, further exacerbating DR. Thus, our study presents new insights into the prevention and treatment of DR.
Topics: Young Adult; Humans; Diabetic Retinopathy; Chronobiology Disorders; Biological Clocks; Circadian Rhythm; Glucose; Diabetes Mellitus
PubMed: 37647688
DOI: 10.1016/j.biopha.2023.115368 -
Philosophical Transactions of the Royal... Jul 2009The present manuscript discusses the time-emotion paradox in time psychology: although humans are able to accurately estimate time as if they possess a specific... (Review)
Review
The present manuscript discusses the time-emotion paradox in time psychology: although humans are able to accurately estimate time as if they possess a specific mechanism that allows them to measure time (i.e. an internal clock), their representations of time are easily distorted by the context. Indeed, our sense of time depends on intrinsic context, such as the emotional state, and on extrinsic context, such as the rhythm of others' activity. Existing studies on the relationships between emotion and time suggest that these contextual variations in subjective time do not result from the incorrect functioning of the internal clock but rather from the excellent ability of the internal clock to adapt to events in one's environment. Finally, the fact that we live and move in time and that everything, every act, takes more or less time has often been neglected. Thus, there is no unique, homogeneous time but instead multiple experiences of time. Our subjective temporal distortions directly reflect the way our brain and body adapt to these multiple time scales.
Topics: Biological Clocks; Brain; Emotions; Humans; Time Perception
PubMed: 19487196
DOI: 10.1098/rstb.2009.0013 -
Photomedicine and Laser Surgery Mar 2018
Topics: Biological Clocks; Brain; Brain Diseases; Humans; Light; Low-Level Light Therapy
PubMed: 29649380
DOI: 10.1089/pho.2018.4445 -
Molecules (Basel, Switzerland) Oct 2020The circadian rhythms are an intrinsic timekeeping system that regulates numerous physiological, biochemical, and behavioral processes at intervals of approximately 24... (Review)
Review
The circadian rhythms are an intrinsic timekeeping system that regulates numerous physiological, biochemical, and behavioral processes at intervals of approximately 24 h. By regulating such processes, the circadian rhythm allows organisms to anticipate and adapt to continuously changing environmental conditions. A growing body of evidence shows that disruptions to the circadian rhythm can lead to various disorders, including cancer. Recently, crucial knowledge has arisen regarding the essential features that underlie the overt circadian rhythm and its influence on physiological outputs. This knowledge suggests that specific small molecules can be utilized to control the circadian rhythm. It has been discovered that these small molecules can regulate circadian-clock-related disorders such as metabolic, cardiovascular, inflammatory, as well as cancer. This review examines the potential use of small molecules for developing new drugs, with emphasis placed on recent progress that has been made regarding the identification of small-molecule clock modulators and their potential use in treating cancer.
Topics: Animals; Antineoplastic Agents; Circadian Clocks; Humans; Molecular Targeted Therapy; Neoplasms; Small Molecule Libraries
PubMed: 33114496
DOI: 10.3390/molecules25214937 -
Developmental Cell Mar 2012For 20 years, researchers have thought that circadian clocks are defined by feedback loops of transcription and translation. The rediscovery of posttranslational... (Review)
Review
For 20 years, researchers have thought that circadian clocks are defined by feedback loops of transcription and translation. The rediscovery of posttranslational circadian oscillators in diverse organisms forces us to rethink this paradigm. Meanwhile, the original "basic" feedback loops of canonical circadian clocks have swelled to include dozens of additional proteins acting in interlocked loops. We review several self-sustained clock mechanisms and propose that minimum requirements for diurnal timekeeping might be simpler than those of actual free-running circadian oscillators. Thus, complex mechanisms of circadian timekeeping might have evolved from random connections between unrelated feedback loops with independent but limited time-telling capability.
Topics: Animals; Biological Clocks; CLOCK Proteins; Circadian Rhythm; Drosophila; Drosophila Proteins; Humans; Protein Processing, Post-Translational; Transcription, Genetic
PubMed: 22421040
DOI: 10.1016/j.devcel.2012.02.007 -
Wiley Interdisciplinary Reviews. RNA Jan 2023Biological time keeping, or the duration and tempo at which biological processes occur, is a phenomenon that drives dynamic molecular and morphological changes that... (Review)
Review
Biological time keeping, or the duration and tempo at which biological processes occur, is a phenomenon that drives dynamic molecular and morphological changes that manifest throughout many facets of life. In some cases, the molecular mechanisms regulating the timing of biological transitions are driven by genetic oscillations, or periodic increases and decreases in expression of genes described collectively as a "molecular clock." In vertebrate animals, molecular clocks play a crucial role in fundamental patterning and cell differentiation processes throughout development. For example, during early vertebrate embryogenesis, the segmentation clock regulates the patterning of the embryonic mesoderm into segmented blocks of tissue called somites, which later give rise to axial skeletal muscle and vertebrae. Segmentation clock oscillations are characterized by rapid cycles of mRNA and protein expression. For segmentation clock oscillations to persist, the transcript and protein molecules of clock genes must be short-lived. Faithful, rhythmic, genetic oscillations are sustained by precise regulation at many levels, including post-transcriptional regulation, and such mechanisms are essential for proper vertebrate development. This article is categorized under: RNA Export and Localization > RNA Localization RNA Turnover and Surveillance > Regulation of RNA Stability Translation > Regulation.
Topics: Animals; Biological Clocks; Vertebrates; Somites; RNA; Gene Expression; Gene Expression Regulation, Developmental
PubMed: 35851751
DOI: 10.1002/wrna.1751 -
Philosophical Transactions of the Royal... Nov 2017Animals should time activities, such as foraging, migration and reproduction, as well as seasonal physiological adaptation, in a way that maximizes fitness. The fitness... (Review)
Review
Animals should time activities, such as foraging, migration and reproduction, as well as seasonal physiological adaptation, in a way that maximizes fitness. The fitness outcome of such activities depends largely on their interspecific interactions; the temporal overlap with other species determines when they should be active in order to maximize their encounters with food and to minimize their encounters with predators, competitors and parasites. To cope with the constantly changing, but predictable structure of the environment, organisms have evolved internal biological clocks, which are synchronized mainly by light, the most predictable and reliable environmental cue (but which can be masked by other variables), which enable them to anticipate and prepare for predicted changes in the timing of the species they interact with, on top of responding to them directly. Here, we review examples where the internal timing system is used to predict interspecific interactions, and how these interactions affect the internal timing system and activity patterns. We then ask how plastic these mechanisms are, how this plasticity differs between and within species and how this variability in plasticity affects interspecific interactions in a changing world, in which light, the major synchronizer of the biological clock, is no longer a reliable cue owing to the rapidly changing climate, the use of artificial light and urbanization.This article is part of the themed issue 'Wild clocks: integrating chronobiology and ecology to understand timekeeping in free-living animals'.
Topics: Animals; Biological Clocks; Circadian Rhythm; Climate Change; Life History Traits; Lighting; Urbanization
PubMed: 28993492
DOI: 10.1098/rstb.2016.0248