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Circadian activity

Inga A Frøland Steindal, Andrew Beale, Yoshiyuki Yamamoto, David Whitmore
Most animals and plants live on the planet exposed to periods of rhythmic light and dark. As such, they have evolved endogenous circadian clocks to regulate their physiology rhythmically, and non-visual light detection mechanisms to set the clock to the environmental light-dark cycle. In the case of fish, circadian pacemakers are not only present in the majority of tissues and cells, but these tissues are themselves directly light-sensitive, expressing a wide range of opsin photopigments. This broad non-visual light sensitivity exists to set the clock, but also impacts a wide range of fundamental cell biological processes, such as DNA repair regulation...
June 14, 2018: Developmental Biology
Julien Dufort-Gervais, Valérie Mongrain, Jonathan Brouillette
Alzheimer's disease (AD) is a debilitating neurodegenerative disease characterized by progressive hippocampal-dependent explicit memory deficits that begin at the onset of the illness. An early hallmark of AD is the accumulation of amyloid-beta (Aß) proteins in brain structures involved in encoding and consolidation of memory, like the hippocampus and prefrontal cortex. Aß neurotoxicity is known to induce synaptic dysfunctions and neuronal death leading to cognitive decline. Another recurrent event observed in AD is sleep disturbances...
June 14, 2018: Neurobiology of Learning and Memory
Swenja Kröller-Schön, Andreas Daiber, Sebastian Steven, Matthias Oelze, Katie Frenis, Sanela Kalinovic, Axel Heimann, Frank P Schmidt, Antonio Pinto, Miroslava Kvandova, Ksenija Vujacic-Mirski, Konstantina Filippou, Markus Dudek, Markus Bosmann, Matthias Klein, Tobias Bopp, Omar Hahad, Philipp S Wild, Katrin Frauenknecht, Axel Methner, Erwin R Schmidt, Steffen Rapp, Hanke Mollnau, Thomas Münzel
Aims: Aircraft noise causes endothelial dysfunction, oxidative stress, and inflammation. Transportation noise increases the incidence of coronary artery disease, hypertension, and stroke. The underlying mechanisms are not well understood. Herein, we investigated effects of phagocyte-type NADPH oxidase (Nox2) knockout and different noise protocols (around-the-clock, sleep/awake phase noise) on vascular and cerebral complications in mice. Methods and results: C57BL/6j and Nox2-/- (gp91phox-/-) mice were exposed to aircraft noise (maximum sound level of 85 dB(A), average sound pressure level of 72 dB(A)) around-the-clock or during sleep/awake phases for 1, 2, and 4 days...
June 14, 2018: European Heart Journal
Anton Delwig, Shawnta Y Chaney, Andrea S Bertke, Jan Verweij, Susana Quirce, Delaine D Larsen, Cindy Yang, Ethan Buhr, Russell VAN Gelder, Juana Gallar, Todd Margolis, David R Copenhagen
A unique class of intrinsically photosensitive retinal ganglion cells in mammalian retinae has been recently discovered and characterized. These neurons can generate visual signals in the absence of inputs from rods and cones, the conventional photoreceptors in the visual system. These light sensitive ganglion cells (mRGCs) express the non-rod, non-cone photopigment melanopsin and play well documented roles in modulating pupil responses to light, photoentrainment of circadian rhythms, mood, sleep and other adaptive light functions...
January 2018: Visual Neuroscience
Jinshuo Fan, Zhilei Lv, Guanghai Yang, Ting Ting Liao, Juanjuan Xu, Feng Wu, Qi Huang, Mengfei Guo, Guorong Hu, Mei Zhou, Limin Duan, Shuqing Liu, Yang Jin
Retinoic acid receptor-related orphan receptors (RORs) include RORα (NR1F1), RORβ (NR1F2), and RORγ (NR1F3). These receptors are reported to activate transcription through ligand-dependent interactions with co-regulators and are involved in the development of secondary lymphoid tissues, autoimmune diseases, inflammatory diseases, the circadian rhythm, and metabolism homeostasis. Researches on RORs contributing to cancer-related processes have been growing, and they provide evidence that RORs are likely to be considered as potential therapeutic targets in many cancers...
2018: Frontiers in Immunology
Vincent van der Vinne, Mark J Bingaman, David R Weaver, Steven J Swoap
Daily torpor is used by small mammals to reduce daily energy expenditure in response to energetic challenges. Optimizing the timing of daily torpor allows mammals to maximize its energetic benefits and, accordingly, torpor typically occurs in the late night and early morning in most species. The regulatory mechanisms underlying such temporal regulation have however not been elucidated. Direct control by the circadian clock and indirect control through the timing of food intake have both been suggested as possible mechanisms...
June 14, 2018: Journal of Experimental Biology
Norman Atkins, Shifang Ren, Nathan G Hatcher, Penny W Burgoon, Jennifer W Mitchell, Jonathan V Sweedler, Martha U Gillette
Daily oscillations of brain and body states are under complex temporal modulation by environmental light and the hypothalamic suprachiasmatic nucleus (SCN), the master circadian clock. To better understand mediators of differential temporal modulation, we characterize neuropeptide releasate profiles by non-selective capture of secreted neuropeptides in an optic nerve-horizontal SCN brain slice model. Releasates are collected following electrophysiological stimulation of the optic nerve/retinohypothalamic tract under conditions that alter the phase of SCN activity state...
June 14, 2018: ACS Chemical Neuroscience
Yuya Tsurudome, Satoru Koyanagi, Takumi Kanemitsu, Chiharu Katamune, Masayuki Oda, Yuki Kanado, Mizuki Kato, Akari Morita, Yu Tahara, Naoya Matsunaga, Shigenobu Shibata, Shigehiro Ohdo
A number of diverse cell-surface proteins are anchored to the cytoskeleton via scaffold proteins. Na+ /H+ exchanger regulatory factor-1 (NHERF1), encoded by the Slc9a3r1 gene, functions as a scaffold protein, which is implicated in the regulation of membrane expression of various cell-surface proteins. Here, we demonstrate that the circadian clock component PERIOD2 (PER2) modulates transcription of the mouse Slc9a3r1 gene, generating diurnal accumulation of NHERF1 in the mouse liver. Basal expression of Slc9a3r1 was dependent on transcriptional activation by p65/p50...
June 13, 2018: Scientific Reports
Stefano Casagranda, Suzanne Touzeau, Delphine Ropers, Jean-Luc Gouzé
BACKGROUND: Understanding the dynamical behaviour of biological systems is challenged by their large number of components and interactions. While efforts have been made in this direction to reduce model complexity, they often prove insufficient to grasp which and when model processes play a crucial role. Answering these questions is fundamental to unravel the functioning of living organisms. RESULTS: We design a method for dealing with model complexity, based on the analysis of dynamical models by means of Principal Process Analysis...
June 14, 2018: BMC Systems Biology
Michaela Golic, Kristin Kräker, Caroline Fischer, Natalia Alenina, Nadine Haase, Florian Herse, Till Schütte, Wolfgang Henrich, Dominik N Müller, Andreas Busjahn, Michael Bader, Ralf Dechend
Aim: Diabetes in pregnancy is a major burden with acute and long-term consequences. Its treatment requires adequate diagnosis and monitoring of therapy. Many experimental research on diabetes during pregnancy has been performed in rats. Recently, continuous blood glucose monitoring of non-pregnant diabetic rats revealed an increased circadian variability of blood glucose that made a single blood glucose measurement per day inappropriate to reflect glycemic status. Continuous blood glucose measurement has never been performed in pregnant rats...
2018: Frontiers in Endocrinology
C A Wyse, X Zhang, M McLaughlin, S M Biello, D Hough, M Bellingham, A M Curtis, J E Robinson, N P Evans
Entrainment of circadian rhythms (CR) to the light dark cycle has been well described under controlled, experimental conditions. However, studies in rodents have reported that rhythms in the laboratory are not always reproduced under field conditions. The aim of this study was to characterise the CR of sheep maintained under conditions of standard UK farm animal husbandry and to investigate the effects of environmental challenges presented by season, weaning and changes in housing on CR. Male sheep (n = 9) were kept at pasture, or group housed in barns, under natural photoperiod for one year...
June 9, 2018: Physiology & Behavior
Panteleimon D Mavroudis, Debra C DuBois, Richard R Almon, William J Jusko
Circadian clocks, present in almost all cells of the body, are entrained to rhythmic changes in the environment (e.g. light/dark cycles). Genes responsible for this timekeeping are named core-clock genes, which through transcriptional feedback interactions mediated by transcription factor binding to Ebox/RRE/Dbox elements can generate oscillatory activity of their expression. By regulating the transcription of other clock-controlled genes (CCGs) circadian information is transmitted to tissue and organ levels...
2018: PloS One
Bárbara González-Fernández, Diana I Sánchez, Irene Crespo, Beatriz San-Miguel, Juan Ortiz de Urbina, Javier González-Gallego, María J Tuñón
Dysregulation of the circadian clock machinery is a critical mechanism in the pathogenesis of fibrosis. This study aimed to investigate whether the antifibrotic effect of melatonin is associated with attenuation of circadian clock pathway disturbances in mice treated with carbon tetrachloride (CCl4 ) and in human hepatic stellate cells line LX2. Mice received CCl4 5 μL/g body weight i.p. twice a week for 4 or 6 weeks. Melatonin was given at 5 or 10 mg/kg/day i.p., beginning 2 weeks after the start of CCl4 administration...
2018: Frontiers in Pharmacology
Atsushi Mukaiyama, Yoshihiko Furuike, Jun Abe, Eiki Yamashita, Takao Kondo, Shuji Akiyama
KaiC, the core oscillator of the cyanobacterial circadian clock, is composed of an N-terminal C1 domain and a C-terminal C2 domain, and assembles into a double-ring hexamer upon ATP binding. Cyclic phosphorylation and dephosphorylation at Ser431 and Thr432 in the C2 domain proceed with a period of approximately 24 h in the presence of other clock proteins, KaiA and KaiB, but recent studies have revealed a crucial role for the C1 ring in determining the cycle period. In this study, we mapped dynamic structural changes of the C1 ring in solution using a combination of site-directed tryptophan mutagenesis and fluorescence spectroscopy...
June 11, 2018: Scientific Reports
John O'Brien, Stewart A Bloomfield
Electrical synaptic transmission via gap junctions underlies direct and rapid neuronal communication in the central nervous system. The diversity of functional roles played by electrical synapses is perhaps best exemplified in the vertebrate retina in which gap junctions are expressed by each of the five major neuronal types. These junctions are highly plastic; they are dynamically regulated by ambient illumination and circadian rhythms acting through light-activated neuromodulators. The networks formed by electrically coupled neurons provide plastic, reconfigurable circuits positioned to play key and diverse roles in the transmission and processing of visual information at every retinal level...
June 11, 2018: Annual Review of Vision Science
Dmytro Grygoryev, Michael R Rountree, Furaha Rwatambuga, Anna Ohlrich, Ayaka Kukino, Matthew P Butler, Charles N Allen, Mitchell S Turker
Mammalian tissues display circadian rhythms in transcription, translation, and histone modifications. Here we asked how an advance of the light-dark cycle alters daily rhythms in the liver epigenome at the H3K4me3 (trimethylation of lysine 4 on histone 3) modification, which is found at active and poised gene promoters. H3K4me3 levels were first measured at 4 time points (zeitgeber time [ZT] 3, 8, 15, and 20) during a normal 12L:12D light-dark cycle. Peak levels were observed during the early dark phase at ZT15 and dropped to low levels around lights-on (ZT0) between ZT20 and ZT3...
June 1, 2018: Journal of Biological Rhythms
Kevin Scott, Petra Harsanyi, Alastair R Lyndon
The effects of simulated electromagnetic fields (EMF), emitted from sub-sea power cables, on the commercially important decapod, edible crab (Cancer pagurus), were assessed. Stress related parameters were measured (l-Lactate, d-Glucose, Haemocyanin and respiration rate) along with behavioural and response parameters (antennular flicking, activity level, attraction/avoidance, shelter preference and time spent resting/roaming) during 24-h periods. Exposure to EMF had no effect on Haemocyanin concentrations, respiration rate, activity level or antennular flicking rate...
June 2018: Marine Pollution Bulletin
Swip Draijer, Inês Chaves, Marco F M Hoekman
Neural stem cells persist in the adult central nervous system as a continuing source of astrocytes, oligodendrocytes and neurons. Various signaling pathways and transcription factors actively maintain this population by regulating cell cycle entry and exit. Similarly, the circadian clock is interconnected with the cell cycle and actively maintains stem cell populations in various tissues. Here, we discuss emerging evidence for an important role of the circadian clock in neural stem cells maintenance. We propose that the NAD+ -dependent deacetylase SIRT1 exerts control over the circadian clock in adult neural stem cell function to limit exhaustion of their population...
June 7, 2018: Progress in Neurobiology
Paula M Wagner, Lucas G Sosa Alderete, Lucas D Gorné, Virginia Gaveglio, Gabriela Salvador, Susana Pasquaré, Mario E Guido
Even in immortalized cell lines, circadian clocks regulate physiological processes in a time-dependent manner, driving transcriptional and metabolic rhythms, the latter being able to persist without transcription. Circadian rhythm disruptions in modern life (shiftwork, jetlag, etc.) may lead to higher cancer risk. Here, we investigated whether the human glioblastoma T98G cells maintained quiescent or under proliferation keep a functional clock and whether cells display differential time responses to bortezomib chemotherapy...
June 7, 2018: Molecular Neurobiology
Mario Caba, Jorge Mendoza
In mammals, the suprachiasmatic nucleus (SCN), the master circadian clock, is mainly synchronized to the environmental light/dark cycle. SCN oscillations are maintained by a molecular clockwork in which certain genes, Period 1-2, Cry1-2, Bmal1, and Clock, are rhythmically expressed. Disruption of these genes leads to a malfunctioning clockwork and behavioral and physiological rhythms are altered. In addition to synchronization of circadian rhythms by light, when subjects are exposed to food for a few hours daily, behavioral and physiological rhythms are entrained to anticipate mealtime, even in the absence of the SCN...
2018: Frontiers in Endocrinology
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