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Circadian Clock

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https://www.readbyqxmd.com/read/27912128/time-to-grow-circadian-regulation-of-growth-and-metabolism-in-photosynthetic-organisms
#1
REVIEW
Santiago Mora-García, María José de Leone, Marcelo Yanovsky
Circadian clocks are molecular devices that help adjust organisms to periodic environmental changes. Although formally described as self-sustaining oscillators that are synchronized by external cues and produce defined outputs, it is increasingly clear that physiological processes not only are regulated by, but also regulate the function of the clock. We discuss three recent examples of the intimate relationships between the function of the clock, growth and metabolism in photosynthetic organisms: the daily tracking of sun by sunflowers, the fine computations plants and cyanobacteria perform to manage carbon reserves and prevent starvation, and the changes in clock parameters that went along with domestication of tomato...
November 29, 2016: Current Opinion in Plant Biology
https://www.readbyqxmd.com/read/27911383/parallel-measurement-of-circadian-clock-gene-expression-and-hormone-secretion-in-human-primary-cell-cultures
#2
Volodymyr Petrenko, Camille Saini, Laurent Perrin, Charna Dibner
Circadian clocks are functional in all light-sensitive organisms, allowing for an adaptation to the external world by anticipating daily environmental changes. Considerable progress in our understanding of the tight connection between the circadian clock and most aspects of physiology has been made in the field over the last decade. However, unraveling the molecular basis that underlies the function of the circadian oscillator in humans stays of highest technical challenge. Here, we provide a detailed description of an experimental approach for long-term (2-5 days) bioluminescence recording and outflow medium collection in cultured human primary cells...
November 11, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/27907092/unconjugated-bile-acids-influence-expression-of-circadian-genes-a-potential-mechanism-for-microbe-host-crosstalk
#3
Kalaimathi Govindarajan, John MacSharry, Patrick G Casey, Fergus Shanahan, Susan A Joyce, Cormac G M Gahan
Disruptions to circadian rhythm in mice and humans have been associated with an increased risk of obesity and metabolic syndrome. The gut microbiota is known to be essential for the maintenance of circadian rhythm in the host suggesting a role for microbe-host interactions in the regulation of the peripheral circadian clock. Previous work suggested a role for gut bacterial bile salt hydrolase (BSH) activity in the regulation of host circadian gene expression. Here we demonstrate that unconjugated bile acids, known to be generated through the BSH activity of the gut microbiota, are potentially chronobiological regulators of host circadian gene expression...
2016: PloS One
https://www.readbyqxmd.com/read/27906111/the-functional-significance-of-the-skeletal-muscle-clock-lessons-from-bmal1-knockout-models
#4
REVIEW
Stefano Schiaffino, Bert Blaauw, Kenneth A Dyar
The circadian oscillations of muscle genes are controlled either directly by the intrinsic muscle clock or by extrinsic factors, such as feeding, hormonal signals, or neural influences, which are in turn regulated by the central pacemaker, the suprachiasmatic nucleus of the hypothalamus. A unique feature of circadian rhythms in skeletal muscle is motor neuron-dependent contractile activity, which can affect the oscillation of a number of muscle genes independently of the muscle clock. The role of the intrinsic muscle clock has been investigated using different Bmal1 knockout (KO) models...
October 13, 2016: Skeletal Muscle
https://www.readbyqxmd.com/read/27906079/muscle-specific-loss-of-bmal1-leads-to-disrupted-tissue-glucose-metabolism-and-systemic-glucose-homeostasis
#5
Brianna D Harfmann, Elizabeth A Schroder, Maureen T Kachman, Brian A Hodge, Xiping Zhang, Karyn A Esser
BACKGROUND: Diabetes is the seventh leading cause of death in the USA, and disruption of circadian rhythms is gaining recognition as a contributing factor to disease prevalence. This disease is characterized by hyperglycemia and glucose intolerance and symptoms caused by failure to produce and/or respond to insulin. The skeletal muscle is a key insulin-sensitive metabolic tissue, taking up ~80 % of postprandial glucose. To address the role of the skeletal muscle molecular clock to insulin sensitivity and glucose tolerance, we generated an inducible skeletal muscle-specific Bmal1 (-/-) mouse (iMSBmal1 (-/-))...
March 30, 2016: Skeletal Muscle
https://www.readbyqxmd.com/read/27898828/population-structure-in-the-model-grass-is-highly-correlated-with-flowering-differences-across-broad-geographic-areas
#6
Ludmila Tyler, Scott J Lee, Nelson D Young, Gregory A DeIulio, Elena Benavente, Michael Reagon, Jessica Sysopha, Riccardo M Baldini, Angelo Troìa, Samuel P Hazen, Ana L Caicedo
The small, annual grass (L.) Beauv., a close relative of wheat ( L.) and barley ( L.), is a powerful model system for cereals and bioenergy grasses. Genome-wide association studies (GWAS) of natural variation can elucidate the genetic basis of complex traits but have been so far limited in by the lack of large numbers of well-characterized and sufficiently diverse accessions. Here, we report on genotyping-by-sequencing (GBS) of 84 , seven , and three accessions with diverse geographic origins including Albania, Armenia, Georgia, Italy, Spain, and Turkey...
July 2016: Plant Genome
https://www.readbyqxmd.com/read/27893733/adarb1-catalyzes-circadian-a-to-i-editing-and-regulates-rna-rhythm
#7
Hideki Terajima, Hikari Yoshitane, Haruka Ozaki, Yutaka Suzuki, Shigeki Shimba, Shinya Kuroda, Wataru Iwasaki, Yoshitaka Fukada
It has been proposed that the CLOCK-ARNTL (BMAL1) complex drives circadian transcription of thousands of genes, including Per and Cry family genes that encode suppressors of CLOCK-ARNTL-dependent transcription. However, recent studies demonstrated that 70-80% of circadian-oscillating mRNAs have no obvious rhythms in their de novo transcription, indicating the potential importance of post-transcriptional regulation. Our CLOCK-ChIP-seq analysis identified rhythmic expression of adenosine deaminase, RNA-specific, B1 (Adarb1, also known as Adar2), an adenosine-to-inosine (A-to-I) RNA-editing enzyme...
November 28, 2016: Nature Genetics
https://www.readbyqxmd.com/read/27892932/reciprocal-regulation-of-carbon-monoxide-metabolism-and-the-circadian-clock
#8
Roman Klemz, Silke Reischl, Thomas Wallach, Nicole Witte, Karsten Jürchott, Sabrina Klemz, Veronika Lang, Stephan Lorenzen, Miriam Knauer, Steffi Heidenreich, Min Xu, Jürgen A Ripperger, Michael Schupp, Ralf Stanewsky, Achim Kramer
Circadian clocks are cell-autonomous oscillators regulating daily rhythms in a wide range of physiological, metabolic and behavioral processes. Feedback of metabolic signals, such as redox state, NAD(+)/NADH and AMP/ADP ratios, or heme, modulate circadian rhythms and thereby optimize energy utilization across the 24-h cycle. We show that rhythmic heme degradation, which generates the signaling molecule carbon monoxide (CO), is required for normal circadian rhythms as well as circadian metabolic outputs. CO suppresses circadian transcription by attenuating CLOCK-BMAL1 binding to target promoters...
November 28, 2016: Nature Structural & Molecular Biology
https://www.readbyqxmd.com/read/27891621/animal-cryptochromes-divergent-roles-in-light-perception-circadian-timekeeping-and-beyond
#9
Alicia K Michael, Jennifer L Fribourgh, Russell N Van Gelder, Carrie L Partch
Cryptochromes are evolutionarily related to the light-dependent DNA repair enzyme photolyase, serving as major regulators of circadian rhythms in insects and vertebrate animals. There are two types of cryptochromes in the animal kingdom: Drosophila-like CRYs that act as non-visual photopigments linking circadian rhythms to the environmental light/dark cycle, and vertebrate-like CRYs that do not appear to sense light directly, but control the generation of circadian rhythms by acting as transcriptional repressors...
November 28, 2016: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/27889186/circadian-homeostasis-of-liver-metabolism-suppresses-hepatocarcinogenesis
#10
Nicole M Kettner, Horatio Voicu, Milton J Finegold, Cristian Coarfa, Arun Sreekumar, Nagireddy Putluri, Chinenye A Katchy, Choogon Lee, David D Moore, Loning Fu
Chronic jet lag induces spontaneous hepatocellular carcinoma (HCC) in wild-type mice following a mechanism very similar to that observed in obese humans. The process initiates with non-alcoholic fatty liver disease (NAFLD) that progresses to steatohepatitis and fibrosis before HCC detection. This pathophysiological pathway is driven by jet-lag-induced genome-wide gene deregulation and global liver metabolic dysfunction, with nuclear receptor-controlled cholesterol/bile acid and xenobiotic metabolism among the top deregulated pathways...
November 14, 2016: Cancer Cell
https://www.readbyqxmd.com/read/27888113/circadian-urinary-citrate-excretion-in-a-rat-model-of-exercise
#11
Paula Nuñez, Irene Diaz, Carmen Perillan, Juan Arguelles, Elena Diaz
AIMS: Circadian rhythms are the approximate 24h biological cycles that function to prepare an organism for daily environmental changes. Circadian rhythms unquestionably play critical roles in metabolic homeostasis and the exercise has emerged as a strong non-photic time cue or zeitgeber in animal models and humans. Numerous studies on the effects of exercise on the citrate synthase activity have been published. Citrate is used to assess energy production or expenditure because it is a substrate of the Krebs Cycle, a cycle for oxidative energy production...
November 22, 2016: Life Sciences
https://www.readbyqxmd.com/read/27885421/role-of-vernalization-mediated-demethylation-in-the-floral-transition-of-brassica-rapa
#12
Weike Duan, Huijun Zhang, Bei Zhang, Xiaoting Wu, Shuaixu Shao, Ying Li, Xilin Hou, Tongkun Liu
Vernalization-mediated demethylation of BrCKA2 (casein kinase II α-subunit) and BrCKB4 (casein kinase II β-subunit) shorten the period of the clock gene BrCCA1 (circadian clock associated 1) in Brassica rapa. Photoperiod and vernalization are two environmental cues involved in the regulation of floral transition, but the ways in which they interact remain unclear. DNA methylation is one of the main mechanisms involved in controlling the functional state of chromatin and gene expression in response to environmental signals...
November 24, 2016: Planta
https://www.readbyqxmd.com/read/27885007/circadian-physiology-of-metabolism
#13
REVIEW
Satchidananda Panda
A majority of mammalian genes exhibit daily fluctuations in expression levels, making circadian expression rhythms the largest known regulatory network in normal physiology. Cell-autonomous circadian clocks interact with daily light-dark and feeding-fasting cycles to generate approximately 24-hour oscillations in the function of thousands of genes. Circadian expression of secreted molecules and signaling components transmits timing information between cells and tissues. Such intra- and intercellular daily rhythms optimize physiology both by managing energy use and by temporally segregating incompatible processes...
November 25, 2016: Science
https://www.readbyqxmd.com/read/27885006/mechanisms-linking-circadian-clocks-sleep-and-neurodegeneration
#14
REVIEW
Erik S Musiek, David M Holtzman
Disruptions of normal circadian rhythms and sleep cycles are consequences of aging and can profoundly affect health. Accumulating evidence indicates that circadian and sleep disturbances, which have long been considered symptoms of many neurodegenerative conditions, may actually drive pathogenesis early in the course of these diseases. In this Review, we explore potential cellular and molecular mechanisms linking circadian dysfunction and sleep loss to neurodegenerative diseases, with a focus on Alzheimer's disease...
November 25, 2016: Science
https://www.readbyqxmd.com/read/27885005/immunity-around-the-clock
#15
REVIEW
Kevin Man, Andrew Loudon, Ajay Chawla
Immunity is a high-cost, high-benefit trait that defends against pathogens and noxious stimuli but whose overactivation can result in immunopathologies and sometimes even death. Because many immune parameters oscillate rhythmically with the time of day, the circadian clock has emerged as an important gatekeeper for reducing immunity-associated costs, which, in turn, enhances organismal fitness. This is mediated by interactions between extrinsic environmental cues and the intrinsic oscillators of immune cells, which together optimize immune responses throughout the circadian cycle...
November 25, 2016: Science
https://www.readbyqxmd.com/read/27885004/circadian-time-signatures-of-fitness-and-disease
#16
REVIEW
Joseph Bass, Mitchell A Lazar
Biological clocks are autonomous anticipatory oscillators that play a critical role in the organization and information processing from genome to whole organisms. Transformative advances into the clock system have opened insight into fundamental mechanisms through which clocks program energy transfer from sunlight into organic matter and potential energy, in addition to cell development and genotoxic stress response. The identification of clocks in nearly every single cell of the body raises questions as to how this gives rise to rhythmic physiology in multicellular organisms and how environmental signals entrain clocks to geophysical time...
November 25, 2016: Science
https://www.readbyqxmd.com/read/27885003/circadian-clocks-not-your-grandfather-s-clock
#17
REVIEW
Fred W Turek
The last 20 years have seen the rapid evolution of our understanding of the molecular genes and networks that enable almost all forms of life to generate 24-hour-or circadian-rhythms. One finding has been particularly exciting: that the molecular circadian clock resides in almost all of the cells of the body and that the clock regulates the timing of many cellular and signaling pathways associated with multiple disease states. Such advances represent a new frontier for medicine: circadian medicine.
November 25, 2016: Science
https://www.readbyqxmd.com/read/27883893/circadian-alterations-during-early-stages-of-alzheimer-s-disease-are-associated-with-aberrant-cycles-of-dna-methylation-in-bmal1
#18
Peter Cronin, Michael J McCarthy, Andrew S P Lim, David P Salmon, Douglas Galasko, Eliezer Masliah, Philip L De Jager, David A Bennett, Paula Desplats
INTRODUCTION: Circadian alterations are prevalent in Alzheimer's disease (AD) and may contribute to cognitive impairment, behavioral symptoms, and neurodegeneration. Epigenetic mechanisms regulate the circadian clock, and changes in DNA methylation have been reported in AD brains, but the pathways that mediate circadian deregulation in AD are incompletely understood. We hypothesized that aberrant DNA methylation may affect circadian rhythms in AD. METHODS: We investigated DNA methylation, transcription, and expression of BMAL1, a positive regulator of the circadian clock, in cultured fibroblasts and brain samples from two independent cohorts of aging and AD...
November 21, 2016: Alzheimer's & Dementia: the Journal of the Alzheimer's Association
https://www.readbyqxmd.com/read/27883226/the-circadian-gene-clock-regulates-bone-formation-via-pdia3
#19
Gongsheng Yuan, Bingxuan Hua, Yang Yang, Lirong Xu, Tingting Cai, Ning Sun, Zuoqin Yan, Chao Lu, Ruizhe Qian
The expression patterns of clock-controlled genes (ccgs) are regulated by circadian rhythm, which is a major regulatory and physiological mechanism tied to the solar day. Disruptions in circadian rhythm contribute to the development of cardiovascular diseases, cancer, metabolic syndromes and aging. It has been reported that bone remodeling is also regulated by circadian rhythm. However, the molecular mechanism by which the circadian gene Clock regulates bone remodeling has yet to be elucidated. Here, we show that Clock mutant mice exhibit a significant reduction in bone density as well as increased apoptosis...
November 24, 2016: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
https://www.readbyqxmd.com/read/27883065/cycles-of-circadian-illuminance-are-sufficient-to-entrain-and-maintain-circadian-locomotor-rhythms-in-drosophila
#20
Eunjoo Cho, Ji Hye Oh, Euna Lee, Young Rag Do, Eun Young Kim
Light at night disrupts the circadian clock and causes serious health problems in the modern world. Here, we show that newly developed four-package light-emitting diodes (LEDs) can provide harmless lighting at night. To quantify the effects of light on the circadian clock, we employed the concept of circadian illuminance (CIL). CIL represents the amount of light weighted toward the wavelengths to which the circadian clock is most sensitive, whereas visual illuminance (VIL) represents the total amount of visible light...
November 24, 2016: Scientific Reports
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