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Circadian Clock

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https://www.readbyqxmd.com/read/28212399/instrument-design-and-protocol-for-the-study-of-light-controlled-processes-in-aquatic-organisms-and-its-application-to-examine-the-effect-of-infrared-light-on-zebrafish
#1
Marcus P S Dekens, Nicholas S Foulkes, Kristin Tessmar-Raible
The acquisition of reliable data strongly depends on experimental design. When studying the effects of light on processes such as behaviour and physiology it is crucial to maintain all environmental conditions constant apart from the one under study. Furthermore, the precise values of the environmental factors applied during the experiment should be known. Although seemingly obvious, these conditions are often not met when the effects of light are being studied. Here, we document and discuss the wavelengths and light intensities of natural and artificial light sources...
2017: PloS One
https://www.readbyqxmd.com/read/28202598/early-flowering-3-redundancy-fine-tunes-photoperiod-sensitivity
#2
Andrew J S Rubenach, Valerie Fg Hecht, Jacqueline K Vander Schoor, Lim Chee Liew, Gregoire Aubert, Judith Burstin, James L Weller
Three pea loci controlling photoperiod sensitivity, HIGH RESPONSE (HR), DIE NEUTRALIS (DNE) and STERILE NODES (SN) have recently been shown to correspond to orthologs of Arabidopsis circadian clock genes EARLY FLOWERING3 (ELF3), ELF4, and LUX ARRHYTHMO, respectively. A fourth pea locus, PHOTOPERIOD (PPD), also contributes to the photoperiod response in a similar manner to SN and DNE, and recessive ppd mutants on a spring-flowering hr mutant background show early, photoperiod-insensitive flowering. However, the molecular identity of PPD has so far remained elusive...
February 15, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28196531/enhancing-circadian-clock-function-in-cancer-cells-inhibits-tumor-growth
#3
Silke Kiessling, Lou Beaulieu-Laroche, Ian D Blum, Dominic Landgraf, David K Welsh, Kai-Florian Storch, Nathalie Labrecque, Nicolas Cermakian
BACKGROUND: Circadian clocks control cell cycle factors, and circadian disruption promotes cancer. To address whether enhancing circadian rhythmicity in tumor cells affects cell cycle progression and reduces proliferation, we compared growth and cell cycle events of B16 melanoma cells and tumors with either a functional or dysfunctional clock. RESULTS: We found that clock genes were suppressed in B16 cells and tumors, but treatments inducing circadian rhythmicity, such as dexamethasone, forskolin and heat shock, triggered rhythmic clock and cell cycle gene expression, which resulted in fewer cells in S phase and more in G1 phase...
February 14, 2017: BMC Biology
https://www.readbyqxmd.com/read/28196106/tor-signaling-pathway-and-autophagy-are-involved-in-the-regulation-of-circadian-rhythms-in-behavior-and-plasticity-of-l2-interneurons-in-the-brain-of-drosophila-melanogaster
#4
Ewelina Kijak, Elżbieta Pyza
Drosophila melanogaster is a common model used to study circadian rhythms in behavior and circadian clocks. However, numerous circadian rhythms have also been detected in non-clock neurons, especially in the first optic neuropil (lamina) of the fly's visual system. Such rhythms have been observed in the number of synapses and in the structure of interneurons, which exhibit changes in size and shape in a circadian manner. Although the patterns of these changes are known, the mechanism remains unclear. In the present study, we investigated the role of the TOR signaling pathway and autophagy in regulating circadian rhythms based on the behavior and structural plasticity of the lamina L2 monopolar cell dendritic trees...
2017: PloS One
https://www.readbyqxmd.com/read/28192242/molecular-cloning-characterization-and-temporal-expression-of-the-clock-genes-period-and-timeless-in-the-oriental-river-prawn-macrobrachium-nipponense-during-female-reproductive-development
#5
SuHua Chen, Hui Qiao, HongTuo Fu, Shengming Sun, WenYi Zhang, ShuBo Jin, Yongsheng Gong, Sufei Jiang, Weiyi Xiong, YanWu
The circadian clock is crucial for sustaining rhythmic biochemical, physiological, and behavioral processes in living creatures. In this study, we isolated and characterized two circadian clock genes in Macrobrachium nipponense, period (Mnper) and timeless (Mntim). The complete Mnper cDNA measures 4283bp in length with an open reading frame encoding 1292 amino acids, including functional domains such as PER-ARNT-SIM (PAS), cytoplasmic localization domain (CLD), TIM interaction site (TIS), and nuclear localization signal (NLS)...
February 10, 2017: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
https://www.readbyqxmd.com/read/28188587/circadian-rhythms-and-substance-abuse-chronobiological-considerations-for-the-treatment-of-addiction
#6
REVIEW
Ian C Webb
Reward-related learning, including that associated with drugs of abuse, is largely mediated by the dopaminergic mesolimbic pathway. Mesolimbic neurophysiology and motivated behavior, in turn, are modulated by the circadian timing system which generates ∼24-h rhythms in cellular activity. Both drug taking and seeking and mesolimbic dopaminergic neurotransmission can vary widely over the day. Moreover, circadian clock genes are expressed in ventral tegmental area dopaminergic cells and in mesolimbic target regions where they can directly modulate reward-related neurophysiology and behavior...
February 2017: Current Psychiatry Reports
https://www.readbyqxmd.com/read/28186138/the-spectral-and-spatial-distribution-of-light-pollution-in-the-waters-of-the-northern-gulf-of-aqaba-eilat
#7
Raz Tamir, Amit Lerner, Carynelisa Haspel, Zvy Dubinsky, David Iluz
The urbanization of the shores of the Gulf of Aqaba has exposed the marine environment there, including unique fringing coral reefs, to strong anthropogenic light sources. Here we present the first in situ measurements of artificial nighttime light under water in such an ecosystem, with irradiance measured in 12 wavelength bands, at 19 measurement stations spread over 44 square km, and at 30 depths down to 30-m depth. At 1-m depth, we find downwelling irradiance values that vary from 4.6 × 10(-4) μW cm(-2) nm(-1) 500 m from the city to 1 × 10(-6) μW cm(-2) nm(-1) in the center of the gulf (9...
February 10, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28186121/astrocyte-deletion-of-bmal1-alters-daily-locomotor-activity-and-cognitive-functions-via-gaba-signalling
#8
Olga Barca-Mayo, Meritxell Pons-Espinal, Philipp Follert, Andrea Armirotti, Luca Berdondini, Davide De Pietri Tonelli
Circadian rhythms are controlled by a network of clock neurons in the central pacemaker, the suprachiasmatic nucleus (SCN). Core clock genes, such as Bmal1, are expressed in SCN neurons and in other brain cells, such as astrocytes. However, the role of astrocytic clock genes in controlling rhythmic behaviour is unknown. Here we show that ablation of Bmal1 in GLAST-positive astrocytes alters circadian locomotor behaviour and cognition in mice. Specifically, deletion of astrocytic Bmal1 has an impact on the neuronal clock through GABA signalling...
February 10, 2017: Nature Communications
https://www.readbyqxmd.com/read/28182648/rna-seq-analysis-of-drosophila-clock-and-non-clock-neurons-reveals-neuron-specific-cycling-and-novel-candidate-neuropeptides
#9
Katharine C Abruzzi, Abigail Zadina, Weifei Luo, Evelyn Wiyanto, Reazur Rahman, Fang Guo, Orie Shafer, Michael Rosbash
Locomotor activity rhythms are controlled by a network of ~150 circadian neurons within the adult Drosophila brain. They are subdivided based on their anatomical locations and properties. We profiled transcripts "around the clock" from three key groups of circadian neurons with different functions. We also profiled a non-circadian outgroup, dopaminergic (TH) neurons. They have cycling transcripts but fewer than clock neurons as well as low expression and poor cycling of clock gene transcripts. This suggests that TH neurons do not have a canonical circadian clock and that their gene expression cycling is driven by brain systemic cues...
February 9, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28177832/natural-variation-in-i-circadian-clock-associated-1-i-is-associated-with-flowering-time-in-i-brassica-rapa-i
#10
Hankuil Yi, Xiaonan Li, Seong Ho Lee, Ill-Sup Nou, Yong Pyo Lim, Yoonkang Hur
Flowering time is a very important agronomic trait and the development of molecular markers associated with this trait can facilitate crop breeding. <i>CIRCADIAN CLOCK ASSOCIATED 1</i> (<i>CCA1</i>), a core oscillator component of circadian rhythms that affect metabolic pathways in plants, has been implicated in flowering time control in <i>Brassica</i> species. <i>CCA1</i> gene sequences from three <i>Brassica rapa</i> inbred lines, showing either early flowering or late flowering phenotypes, were analyzed and a high level of ets were designed and tested using various inbred lines of <i>B...
December 22, 2016: Genome Génome / Conseil National de Recherches Canada
https://www.readbyqxmd.com/read/28174256/a-time-for-myc-metabolism-and-therapy
#11
Chi V Dang
The MYC oncogene is frequently deregulated in human cancers, whereas the proto-oncogene is exquisitely, tightly regulated in normal cells. Deregulated MYC drives transcriptional imbalance, thereby altering metabolism and disrupting the circadian Bmal1-Clock E-box-dependent transcriptional circuitry. Sustained oncogenic MYC expression drives a constitutive growth program with mammalian target of rapamycin (mTOR) activation that renders cells dependent on nutrients, such that glucose or glutamine deprivation could trigger cell death and key enzymes such as lactate dehydrogenase A (LDHA) and glutaminase (GLS) amenable for targeting in cancers...
February 7, 2017: Cold Spring Harbor Symposia on Quantitative Biology
https://www.readbyqxmd.com/read/28174180/suprachiasmatic-vasopressin-to-paraventricular-oxytocin-neurocircuit-in-the-hypothalamus-relays-light-reception-to-inhibition-of-feeding-behavior
#12
Putra Santoso, Masanori Nakata, Yoichi Ueta, Toshihiko Yada
Light syncronizes body's circadian rhythms by modulating the master clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus. In modern life, the extended and/or irregular light exposure impairs circadian rhythms and consequently promotes feeding and metabolic disorders. However, the neuronal pathway through which light is coupled to feeding behavior is less elucidated. The present study employed the light exposure during dark phase of the day in rats and observed its effect on neuronal activity and feeding behavior...
February 7, 2017: American Journal of Physiology. Endocrinology and Metabolism
https://www.readbyqxmd.com/read/28165421/circadian-rhythms-and-hormonal-homeostasis-pathophysiological-implications
#13
REVIEW
Davide Gnocchi, Giovannella Bruscalupi
Over recent years, a deeper comprehension of the molecular mechanisms that control biological clocks and circadian rhythms has been achieved. In fact, many studies have contributed to unravelling the importance of the molecular clock for the regulation of our physiology, including hormonal and metabolic homeostasis. Here we will review the structure, organisation and molecular machinery that make our circadian clock work, and its relevance for the proper functioning of physiological processes. We will also describe the interconnections between circadian rhythms and endocrine homeostasis, as well as the underlying consequences that circadian dysregulations might have in the development of several pathologic affections...
February 4, 2017: Biology
https://www.readbyqxmd.com/read/28164454/nutrition-movement-and-sleep-behaviours-their-interactions-in-pathways-to-obesity-and-cardiometabolic-diseases
#14
A G Dulloo, J L Miles-Chan, J-P Montani
Among the multitude of dietary and lifestyle behaviours that have been proposed to contribute to the obesity epidemic, those that have generated considerable research scrutiny in the past decade are centred upon sleep behaviours, sedentary behaviours (sitting or lying while awake) and diminished low-level physical activities of everyday life, with each category of behaviours apparently presenting an independent risk for obesity and/or cardiometabolic diseases. These behaviours are highly complex, operate in synergy with each other, disrupt the link between regulation of the circadian clock and metabolic physiology and impact on various components of daily energy expenditure and feeding behaviours to promote obesity and hinder the outcome of obesity therapy...
February 2017: Obesity Reviews: An Official Journal of the International Association for the Study of Obesity
https://www.readbyqxmd.com/read/28164453/the-circadian-clock-metabolism-and-obesity
#15
REVIEW
U Albrecht
In the last decades, obesity has been on the rise becoming a burden for health care systems. The reasons behind this rise are most likely caused by lifestyle rather than by an increase in gene mutations, because manifestations of genetic alterations would take longer than just a few decades. Lifestyle has a great impact on the circadian system and therefore on the body internal organization of physiological and biochemical processes, regulating various aspects of behavior and metabolism. In the following, I will discuss recent studies delineating relationships between metabolic processes and the circadian system, how metabolites and nutrients regulate the circadian clock and how nuclear receptors can act as metabolic sensors and clock regulators...
February 2017: Obesity Reviews: An Official Journal of the International Association for the Study of Obesity
https://www.readbyqxmd.com/read/28164449/role-of-sleep-and-circadian-disruption-on-energy-expenditure-and-in-metabolic-predisposition-to-human-obesity-and-metabolic-disease
#16
REVIEW
A W McHill, K P Wright
Weight gain, obesity and diabetes have reached alarming levels in the developed world. Traditional risk factors such as over-eating, poor nutritional choices and lack of exercise cannot fully account for the high prevalence of metabolic disease. This review paper examines the scientific evidence on two novel risk factors that contribute to dys-regulated metabolic physiology: sleep disruption and circadian misalignment. Specifically, fundamental relationships between energy metabolism and sleep and circadian rhythms and the impact of sleep and circadian disruption on metabolic physiology are examined...
February 2017: Obesity Reviews: An Official Journal of the International Association for the Study of Obesity
https://www.readbyqxmd.com/read/28162920/how-does-general-anaesthesia-affect-the-circadian-clock
#17
REVIEW
Raewyn C Poulsen, Guy R Warman, Jamie Sleigh, Nicola M Ludin, James F Cheeseman
: Post-operative patients experience sleep disturbances. Animal studies demonstrate that general anaesthesia (GA) can disrupt circadian rhythms and cause changes in the molecular clock, indicating that anaesthesia contributes to post-operative circadian disruption. Here we review the effect of anaesthesia on the circadian clock and its rhythms in order to summarise current findings outline commonalities between studies and propose mechanisms by which effects may be mediated. KEY POINTS: 1) GA has strong effects on the main neurotransmitter systems linked with circadian control (Gamma aminobutyric acid/N-methyl-D-aspartate (GABA/NMDA)) and may act by interfering with light-entrainment of the clock...
December 18, 2016: Sleep Medicine Reviews
https://www.readbyqxmd.com/read/28162893/circadian-entrainment-to-the-natural-light-dark-cycle-across-seasons-and-the-weekend
#18
Ellen R Stothard, Andrew W McHill, Christopher M Depner, Brian R Birks, Thomas M Moehlman, Hannah K Ritchie, Jacob R Guzzetti, Evan D Chinoy, Monique K LeBourgeois, John Axelsson, Kenneth P Wright
Reduced exposure to daytime sunlight and increased exposure to electrical lighting at night leads to late circadian and sleep timing [1-3]. We have previously shown that exposure to a natural summer 14 hr 40 min:9 hr 20 min light-dark cycle entrains the human circadian clock to solar time, such that the internal biological night begins near sunset and ends near sunrise [1]. Here we show that the beginning of the biological night and sleep occur earlier after a week's exposure to a natural winter 9 hr 20 min:14 hr 40 min light-dark cycle as compared to the modern electrical lighting environment...
February 2, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28160289/melanopsin-expressing-human-retinal-ganglion-cells-subtypes-distribution-and-intraretinal-connectivity
#19
Jens Hannibal, Anders Tolstrup Christensen, Steffen Heegaard, Jan Fahrenkrug, Jens Folke Kiilgaard
Intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing the photopigment melanopsin belong to a heterogenic population of RGCs which regulate the circadian clock, masking behavior, melatonin suppression, the pupillary light reflex and sleep/wake cycles. The different functions seem to be associated to different subtypes of melanopsin cells. In rodents, subtype classification has associated subtypes to function. In primate and human retina such classification has so far, not been applied. In the present study using antibodies against N- and C-terminal parts of human melanopsin, confocal microscopy and 3D reconstruction of melanopsin immunoreactive (-ir) RGCs, we applied the criteria used in mouse on human melanopsin-ir RGCs...
February 3, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28159888/principles-for-circadian-orchestration-of-metabolic-pathways
#20
Kevin Thurley, Christopher Herbst, Felix Wesener, Barbara Koller, Thomas Wallach, Bert Maier, Achim Kramer, Pål O Westermark
Circadian rhythms govern multiple aspects of animal metabolism. Transcriptome-, proteome- and metabolome-wide measurements have revealed widespread circadian rhythms in metabolism governed by a cellular genetic oscillator, the circadian core clock. However, it remains unclear if and under which conditions transcriptional rhythms cause rhythms in particular metabolites and metabolic fluxes. Here, we analyzed the circadian orchestration of metabolic pathways by direct measurement of enzyme activities, analysis of transcriptome data, and developing a theoretical method called circadian response analysis...
February 3, 2017: Proceedings of the National Academy of Sciences of the United States of America
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