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Biological clock

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https://www.readbyqxmd.com/read/28742083/long-time-analytic-approximation-of-large-stochastic-oscillators-simulation-analysis-and-inference
#1
Giorgos Minas, David A Rand
In order to analyse large complex stochastic dynamical models such as those studied in systems biology there is currently a great need for both analytical tools and also algorithms for accurate and fast simulation and estimation. We present a new stochastic approximation of biological oscillators that addresses these needs. Our method, called phase-corrected LNA (pcLNA) overcomes the main limitations of the standard Linear Noise Approximation (LNA) to remain uniformly accurate for long times, still maintaining the speed and analytically tractability of the LNA...
July 24, 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28724246/health-consequences-of-electric-lighting-practices-in-the-modern-world-a-report-on-the-national-toxicology-program-s-workshop-on-shift-work-at-night-artificial-light-at-night-and-circadian-disruption
#2
REVIEW
Ruth M Lunn, David E Blask, Andrew N Coogan, Mariana G Figueiro, Michael R Gorman, Janet E Hall, Johnni Hansen, Randy J Nelson, Satchidananda Panda, Michael H Smolensky, Richard G Stevens, Fred W Turek, Roel Vermeulen, Tania Carreón, Claire C Caruso, Christina C Lawson, Kristina A Thayer, Michael J Twery, Andrew D Ewens, Sanford C Garner, Pamela J Schwingl, Windy A Boyd
The invention of electric light has facilitated a society in which people work, sleep, eat, and play at all hours of the 24-hour day. Although electric light clearly has benefited humankind, exposures to electric light, especially light at night (LAN), may disrupt sleep and biological processes controlled by endogenous circadian clocks, potentially resulting in adverse health outcomes. Many of the studies evaluating adverse health effects have been conducted among night- and rotating-shift workers, because this scenario gives rise to significant exposure to LAN...
July 15, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28712565/circadian-clock-involvement-in-zooplankton-diel-vertical-migration
#3
N Sören Häfker, Bettina Meyer, Kim S Last, David W Pond, Lukas Hüppe, Mathias Teschke
Biological clocks are a ubiquitous ancient and adaptive mechanism enabling organisms to anticipate environmental cycles and to regulate behavioral and physiological processes accordingly [1]. Although terrestrial circadian clocks are well understood, knowledge of clocks in marine organisms is still very limited [2-5]. This is particularly true for abundant species displaying large-scale rhythms like diel vertical migration (DVM) that contribute significantly to shaping their respective ecosystems [6]. Here we describe exogenous cycles and endogenous rhythms associated with DVM of the ecologically important and highly abundant planktic copepod Calanus finmarchicus...
July 24, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28697366/circadian-biology-uncoupling-human-body-clocks-by%C3%A2-food-timing
#4
Celine Vetter, Frank A J L Scheer
Synchrony of circadian rhythms between tissues/organs appears critical for health. A new study reports that meal timing, a modifiable temporal cue for the circadian system, can selectively uncouple circadian rhythms in metabolic physiology from the central circadian clock in humans.
July 10, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28689714/thermal-stress-in-danio-rerio-a-link-between-temperature-light-thermo-trp-channels-and-clock-genes
#5
Rodrigo Jerônimo, Maria Nathália Moraes, Leonardo Vinícius Monteiro de Assis, Bruno César Ramos, Thainá Rocha, Ana Maria de Lauro Castrucci
It is believed that the biological systems perceiving temperature and light daily cycles were subjected to the simultaneous selective pressures, which resulted in their co-evolutionary association. We investigated the influence of 1h 33°C heat shock on the expression of clock and heat shock protein genes, as well as the role of the thermo-TRP channel, TRPV1, in ZEM-2S cells of the teleost Danio rerio, in constant dark (DD) or light-dark cycles (LD). After heat shock, we observed an acute increase of hsp90 aa1 levels in both DD and LD conditions...
August 2017: Journal of Thermal Biology
https://www.readbyqxmd.com/read/28686160/the-cyanobacterial-circadian-clock-follows-midday-in-vivo-and-in-vitro
#6
Eugene Leypunskiy, Jenny Lin, Haneul Yoo, UnJin Lee, Aaron R Dinner, Michael J Rust
Circadian rhythms are biological oscillations that schedule daily changes in physiology. Outside the laboratory, circadian clocks do not generally free-run, but are driven by daily cues whose timing varies with the seasons. The principles that determine how circadian clocks align to these external cycles are not well understood. Here we report experimental platforms for driving the cyanobacterial circadian clock both in vivo and in vitro. We find that the phase of the circadian rhythm follows a simple scaling law in light-dark cycles, tracking midday across conditions with variable day length...
July 7, 2017: ELife
https://www.readbyqxmd.com/read/28679948/prl2-links-magnesium-flux-and-sex-dependent-circadian-metabolic-rhythms
#7
Noriko Uetani, Serge Hardy, Simon-Pierre Gravel, Silke Kiessling, Adam Pietrobon, Nau Nau Wong, Valérie Chénard, Nicolas Cermakian, Julie St-Pierre, Michel L Tremblay
Magnesium (Mg2+) plays pleiotropic roles in cellular biology, and it is essentially required for all living organisms. Although previous studies demonstrated intracellular Mg2+ levels were regulated by the complex of phosphatase of regenerating liver 2 (PRL2) and Mg2+ transporter of cyclin M (CNNMs), physiological functions of PRL2 in whole animals remain unclear. Interestingly, Mg2+ was recently identified as a regulator of circadian rhythm-dependent metabolism; however, no mechanism was found to explain the clock-dependent Mg2+ oscillation...
July 6, 2017: JCI Insight
https://www.readbyqxmd.com/read/28679357/genome-scale-analysis-of-regulatory-protein-acetylation-enzymes-from-photosynthetic-eukaryotes
#8
R Glen Uhrig, Pascal Schläpfer, Devang Mehta, Matthias Hirsch-Hoffmann, Wilhelm Gruissem
BACKGROUND: Reversible protein acetylation occurring on Lys-N(e) has emerged as a key regulatory post-translational modification in eukaryotes. It is mediated by two groups of enzymes: lysine acetyltransferases (KATs) and lysine deacetylases (KDACs) that catalyze the addition and removal of acetyl groups from target proteins. Estimates indicate that protein acetylation is second to protein phosphorylation in abundance, with thousands of acetylated sites now identified in different subcellular compartments...
July 5, 2017: BMC Genomics
https://www.readbyqxmd.com/read/28677913/identification-of-the-prothoracicotropic-hormone-ptth-coding-gene-and-localization-of-its-site-of-expression-in-the-pea-aphid-acyrthosiphon-pisum
#9
M Barberà, D Martínez-Torres
Insect hormones control essential aspects of physiology, behaviour and development in insects. The majority of insect hormones are peptide hormones that perform a highly diverse catalogue of functions. Prothoracicotropic hormone (PTTH) is a brain neuropeptide hormone whose main function is to stimulate the secretion of ecdysone (the moulting hormone) by the prothoracic glands in insect larvae thus playing a key role in the control of moulting and metamorphosis. Moreover, both PTTH release or blockade have been reported to act as a switch to terminate or initiate larval and pupal diapauses...
July 5, 2017: Insect Molecular Biology
https://www.readbyqxmd.com/read/28669798/the-pars-tuberalis-the-site-of-the-circannual-clock-in-mammals
#10
REVIEW
Shona Wood, Andrew Loudon
Accurate timing and physiological adaptation to anticipate seasonal changes are an essential requirement for an organism's survival. In contrast to all other environmental cues, photoperiod offers a highly predictive signal that can be reliably used to activate a seasonal adaptive programme at the correct time of year. Coupled to photoperiod sensing, it is apparent that many organisms have evolved innate long-term timekeeping systems, allowing reliable anticipation of forthcoming environmental changes. The fundamental biological processes giving rise to innate long-term timing, with which the photoperiod-sensing pathway engages, are not known for any organism...
June 30, 2017: General and Comparative Endocrinology
https://www.readbyqxmd.com/read/28663488/characterizing-a-12-hour-biological-clock
#11
L Bryan Ray
No abstract text is available yet for this article.
June 30, 2017: Science
https://www.readbyqxmd.com/read/28659440/surf-s-up-for-er-stress
#12
Jeffrey Haspel
A new type of biological clock regulates the unfolded protein response.
June 28, 2017: Science Translational Medicine
https://www.readbyqxmd.com/read/28654075/clock-scan-protocol-for-image-analysis-imagej-plugins
#13
Maxim Dobretsov, Georg Petkau, Abdallah Hayar, Eugen Petkau
The clock scan protocol for image analysis is an efficient tool to quantify the average pixel intensity within, at the border, and outside (background) a closed or segmented convex-shaped region of interest, leading to the generation of an averaged integral radial pixel-intensity profile. This protocol was originally developed in 2006, as a visual basic 6 script, but as such, it had limited distribution. To address this problem and to join similar recent efforts by others, we converted the original clock scan protocol code into two Java-based plugins compatible with NIH-sponsored and freely available image analysis programs like ImageJ or Fiji ImageJ...
June 19, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28649877/retrospective-cohort-study-and-biobanking-of-patients-treated-for-hemangioma-in-childhood-telomeres-as-biomarker-of-aging-and-radiation-exposure
#14
Monika Frenzel, Michelle Ricoul, Mohamed Amine Benadjaoud, Marion Bellamy, Aude Lenain, Nadia Haddy, Ibrahima Diallo, Christine Mateus, Florent de Vathaire, Laure Sabatier
PURPOSE: Cohorts allowing joint epidemiological and biological analyses are essential for radiation risk assessment. The French Hemangioma Cohort (FHC), studied within the European project EpiRadBio, is one of the rare cohorts suitable for studying the effect of low dose radiation exposure (<100 mGy at organs), with a long-term follow-up. This highly homogeneous cohort consists of healthy individuals belonging to a normal population, except for the presence of skin hemangioma (age at exposure: between 6 months and 3 years of age)...
June 26, 2017: International Journal of Radiation Biology
https://www.readbyqxmd.com/read/28645331/circadian-clock-gene-polymorphisms-in-relation-to-sleep-patterns-and-obesity-in-african-americans-findings-from-the-jackson-heart-study
#15
Pia Riestra, Samson Y Gebreab, Ruihua Xu, Rumana J Khan, Amadou Gaye, Adolfo Correa, Nancy Min, Mario Sims, Sharon K Davis
BACKGROUND: Circadian rhythms regulate key biological processes and the dysregulation of the intrinsic clock mechanism affects sleep patterns and obesity onset. The CLOCK (circadian locomotor output cycles protein kaput) gene encodes a core transcription factor of the molecular circadian clock influencing diverse metabolic pathways, including glucose and lipid homeostasis. The primary objective of this study was to evaluate the associations between CLOCK single nucleotide polymorphisms (SNPs) and body mass index (BMI)...
June 23, 2017: BMC Genetics
https://www.readbyqxmd.com/read/28635334/timing-of-food-intake-during-simulated-night-shift-impacts-glucose-metabolism-a-controlled-study
#16
Crystal L Grant, Alison M Coates, Jillian Dorrian, David J Kennaway, Gary A Wittert, Leonie K Heilbronn, Maja Pajcin, Chris Della Vedova, Charlotte C Gupta, Siobhan Banks
Eating during the night may increase the risk for obesity and type 2 diabetes in shift workers. This study examined the impact of either eating or not eating a meal at night on glucose metabolism. Participants underwent four nights of simulated night work (SW1-4, 16:00-10:00 h, <50 lux) with a daytime sleep opportunity each day (10:00-16:00 h, <3 lux). Healthy males were assigned to an eating at night (NE; n = 4, meals; 07:00, 19:00 and 01:30 h) or not eating at night (NEN; n = 7, meals; 07:00 h, 09:30, 16:10 and 19:00 h) condition...
June 21, 2017: Chronobiology International
https://www.readbyqxmd.com/read/28619534/cryptochrome-photoreceptors-in-green-algae-unexpected-versatility-of-mechanisms-and-functions
#17
Tilman Kottke, Sabine Oldemeyer, Sandra Wenzel, Yong Zou, Maria Mittag
Green algae have a highly complex and diverse set of cryptochrome photoreceptor candidates including members of the following subfamilies: plant, plant-like, animal-like, DASH and cryptochrome photolyase family 1 (CPF1). While some green algae encode most or all of them, others lack certain members. Here we present an overview about functional analyses of so far investigated cryptochrome photoreceptors from the green algae Chlamydomonas reinhardtii (plant and animal-like cryptochromes) and Ostreococcus tauri (CPF1) with regard to their biological significance and spectroscopic properties...
May 31, 2017: Journal of Plant Physiology
https://www.readbyqxmd.com/read/28619182/evolution-of-circadian-rhythms-from-bacteria-to-human
#18
REVIEW
Utpal Bhadra, Nirav Thakkar, Paromita Das, Manika Pal Bhadra
The human body persists in its rhythm as per its initial time zone, and transition always occur according to solar movements around the earth over 24 h. While traveling across different latitudes and longitudes, at the pace exceeding the earth's movement, the changes in the external cues exceed the level of toleration of the body's biological clock. This poses an alteration in our physiological activities of sleep-wake pattern, mental alertness, organ movement, and eating habits, causing them to temporarily lose the track of time...
July 2017: Sleep Medicine
https://www.readbyqxmd.com/read/28617195/light-and-clock-control-of-genes-involved-in-detoxification
#19
G Carmona-Antoñanzas, M Santi, H Migaud, L M Vera
Circadian regulation of hepatic detoxification seems to be amongst the key roles of the biological clock. The liver is the major site for biotransformation, and in mammals, it contains several clock-controlled transcription factors such as proline and acidic amino acid-rich basic leucine zipper proteins (PAR bZIP) and basic-helix-loop-helix Per-Arnt-Sim (bHLH-PAS) family that act as circadian regulators of detoxification genes. This investigation explored the existence of daily and circadian expression of transcription factors involved in detoxification, as well as the temporal profile of a set of their target genes in zebrafish liver...
June 15, 2017: Chronobiology International
https://www.readbyqxmd.com/read/28603481/effects-of-dim-light-at-night-on-food-intake-and-body-mass-in-developing-mice
#20
Yasmine M Cissé, Juan Peng, Randy J Nelson
Appropriately timed light is critical for circadian organization; exposure to dim light at night (dLAN) disrupts temporal organization of endogenous biological timing. Exposure to dLAN in adult mice is associated with elevated body mass and changes in metabolism putatively driven by voluntary changes in the time of food intake. We predicted that exposure of young mice to LAN could affect adult metabolic function. At 3 weeks (Experiment 1) or 5 weeks (Experiment 2) of age, mice were either maintained in standard light-dark (DARK) cycles or exposed to nightly dLAN (5 lux)...
2017: Frontiers in Neuroscience
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