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Journal of Biological Rhythms

Nicholas Bulthuis, Katrina R Spontak, Benjamin Kleeman, Daniel J Cavanaugh
Circadian rhythms in behavior and physiology are produced by central brain clock neurons that can be divided into subpopulations based on molecular and functional characteristics. It has become clear that coherent behavioral rhythms result from the coordinated action of these clock neuron populations, but many questions remain regarding the organizational logic of the clock network. Here we used targeted genetic tools in Drosophila to eliminate either molecular clock function or neuronal activity in discrete clock neuron subsets...
April 17, 2019: Journal of Biological Rhythms
Koki Yamaguchi, Shin G Goto
Many temperate insects enter diapause (dormancy) for overwintering in response to short days (long nights). A latitudinal cline in the critical day lengths for the photoperiodic induction of diapause has been reported in various insect species. However, the physiological mechanisms underlying this cline have remained elusive. We approached this issue in the flesh fly Sarcophaga similis, in which the photoperiodic time measurement system meets the "external coincidence model." In this model, measuring day lengths depends on whether the photoinducible phase (φi ), determined by a circadian clock, is exposed to light or not...
April 9, 2019: Journal of Biological Rhythms
Kento Ikeda, Takaaki Daimon, Hideki Sezutsu, Hiroko Udaka, Hideharu Numata
In Lepidoptera, the roles of period ( per) and the negative feedback involving this gene in circadian rhythm are controversial. In the present study, we established a per knockout strain using TALEN in Bombyx mori, and compared eclosion and hatching rhythms between the per-knockout and wild-type strains to examine whether per is actually involved in these rhythms. The generated per knockout allele was considered null, because it encoded an extensively truncated form of PERIOD (198 aa due to a 64-bp deletion in exon 7, in contrast to 1113 aa in the wild-type protein)...
April 5, 2019: Journal of Biological Rhythms
Manishi Srivastava, Vishwanath Varma, Lakshman Abhilash, Vijay Kumar Sharma, Vasu Sheeba
The stability of circadian clock mechanisms under cyclic environments contributes to increased Darwinian fitness by accurately timing daily behavior and physiology. Earlier studies on biological clocks speculated that the timing of behavior and its accuracy are determined by the intrinsic period (τ) of the circadian clock under constant conditions, its stability, the period of the external cycle (T), and resetting of the clock by environmental time cues. However, most of these previous studies suffered from certain limitations, the major ones being a narrow range of examined τ values and a non-uniformity in the genetic background across the individuals tested...
April 2, 2019: Journal of Biological Rhythms
Sofia Vilela, Andreia Oliveira, Milton Severo, Carla Lopes
The time of eating has been considered to have an important role in weight regulation. However, it is unknown if there are specific daily patterns of energy and macronutrient distribution that could be more beneficial for metabolic outcomes, especially obesity. This study aimed to assess the effect of time-of-day energy and macronutrient intake at 4 y of age on the weight status at 7 y of age. The study sample included 1961 children from the population-based birth cohort Generation XXI, with data on 3-day food diaries at 4 y and body mass index (BMI) z-scores at 7 y...
March 28, 2019: Journal of Biological Rhythms
Andrew D Beale, Emily Kruchek, Stephen J Kitcatt, Erin A Henslee, Jack S W Parry, Gabriella Braun, Rita Jabr, Malcolm von Schantz, John S O'Neill, Fatima H Labeed
Temperature compensation and period determination by casein kinase 1 (CK1) are conserved features of eukaryotic circadian rhythms, whereas the clock gene transcription factors that facilitate daily gene expression rhythms differ between phylogenetic kingdoms. Human red blood cells (RBCs) exhibit temperature-compensated circadian rhythms, which, because RBCs lack nuclei, must occur in the absence of a circadian transcription-translation feedback loop. We tested whether period determination and temperature compensation are dependent on CKs in RBCs...
March 21, 2019: Journal of Biological Rhythms
Jia Zhao, Guy Robert Warman, Ralf Stanewsky, James Frederick Cheeseman
The importance of the circadian clock for the control of behavior and physiology is well established but how and when it develops is not fully understood. Here the initial expression pattern of the key clock gene period was recorded in Drosophila from embryos in vivo, using transgenic luciferase reporters. PERIOD expression in the presumptive central-clock dorsal neurons started to oscillate in the embryo in constant darkness. In behavioral experiments, a single 12-h light pulse given during the embryonic stage synchronized adult activity rhythms, implying the early development of entrainment mechanisms...
March 18, 2019: Journal of Biological Rhythms
Vendula Čečmanová, Pavel Houdek, Karolína Šuchmanová, Martin Sládek, Alena Sumová
The adult circadian clock in the suprachiasmatic nucleus (SCN) of the hypothalamus is resilient to glucocorticoids (GCs). The fetal rodent SCN resembles that of the adult in its organization of GC-sensitive peripheral tissues. We tested the hypothesis that the fetal SCN clock is sensitive to changes in GC levels. Maternal GCs must pass through the placenta to reach the fetal SCN. We show that the maternal but not the fetal part of the placenta harbors the autonomous circadian clock, which is reset by dexamethasone (DEX) and rhythmically expresses Hsd11b2...
March 11, 2019: Journal of Biological Rhythms
Rohan Nagare, Mark S Rea, Barbara Plitnick, Mariana G Figueiro
The intrinsically photosensitive retinal ganglion cells are the main conduit of the light signal emanating from the retina to the biological clock located in the suprachiasmatic nuclei of the hypothalamus. Lighting manufacturers are developing white light sources that are devoid of wavelengths around 480 nm ("cyan gap") to reduce their impact on the circadian system. The present study was designed to investigate whether exposure to a "cyan-gap," 3000 K white light source, spectrally tuned to reduce radiant power between 475 and 495 nm (reducing stimulation of the melanopsin-containing photoreceptor), would suppress melatonin less than a conventional 3000 K light source...
March 1, 2019: Journal of Biological Rhythms
Jiajia Li, Renee Yin Yu, Farida Emran, Brian E Chen, Michael E Hughes
The circadian clock is an evolutionarily conserved mechanism that generates the rhythmic expression of downstream genes. The core circadian clock drives the expression of clock-controlled genes, which in turn play critical roles in carrying out many rhythmic physiological processes. Nevertheless, the molecular mechanisms by which clock output genes orchestrate rhythmic signals from the brain to peripheral tissues are largely unknown. Here we explored the role of one rhythmic gene, Achilles, in regulating the rhythmic transcriptome in the fly head...
February 25, 2019: Journal of Biological Rhythms
Rohan Nagare, Mark S Rea, Barbara Plitnick, Mariana G Figueiro
The human circadian system is primarily regulated by the 24-h LD cycle incident on the retina, and nocturnal melatonin suppression is a primary outcome measure for characterizing the biological clock's response to those light exposures. A limited amount of data related to the combined effects of light level, spectrum, and exposure duration on nocturnal melatonin suppression has impeded the development of circadian-effective lighting recommendations and light-treatment methods. The study's primary goal was to measure nocturnal melatonin suppression for a wide range of light levels (40 to 1000 lux), 2 white light spectra (2700 K and 6500 K), and an extended range of nighttime light exposure durations (0...
February 25, 2019: Journal of Biological Rhythms
Gina Marie Mathew, Lauren Hale, Anne-Marie Chang
Social jetlag, a misalignment between sleep timing on the weekend and during the work week, is associated with depressive symptoms among adults across both sexes. A previous study found that later sleep timing was associated with depressive symptoms in women but not men. To date, however, no research has investigated whether the association between social jetlag and depression varies by sex among adolescents. The current study assessed self-reported sleep, depressive symptoms, and demographic information from 3058 adolescents (48% female, mean [SD] age 15...
February 18, 2019: Journal of Biological Rhythms
Nadia Saderi, Adrián Báez-Ruiz, Lucia E Azuara-Álvarez, Carolina Escobar, Roberto C Salgado-Delgado
The circadian system drives the temporal organization of body physiology in relation to the changing daily environment. Shift-work (SW) disrupts this temporal order and is associated with the loss of homeostasis and metabolic syndrome. In a rodent model of SW based on forced activity in the rest phase for 4 weeks, we describe the occurrence of circadian desynchrony, as well as metabolic and liver dysfunction. To provide better evidence for the impact of altered timing of activity, this study explored how long it takes to recover metabolic rhythms and behavior...
February 15, 2019: Journal of Biological Rhythms
Manpreet Kaur, Amy Ng, Pyonghwa Kim, Casey Diekman, Yong-Ick Kim
Cyanobacteria contain a circadian oscillator that can be reconstituted in vitro. In the reconstituted circadian oscillator, the phosphorylation state of KaiC oscillates with a circadian period, spending about 12 h in the phosphorylation phase and another 12 h in the dephosphorylation phase. Although some entrainment studies have been performed using the reconstituted oscillator, they were insufficient to fully explain entrainment mechanisms of the cyanobacterial circadian clock due to the lack of input pathway components in the in vitro oscillator reaction mixture...
February 13, 2019: Journal of Biological Rhythms
David Resuehr, Gang Wu, Russell L Johnson, Martin E Young, John B Hogenesch, Karen L Gamble
Circadian misalignment between sleep and behavioral/feeding rhythms is thought to lead to various health impairments in shift workers. Therefore, we investigated how shift work leads to genome-wide circadian dysregulation in hospital nurses. Female nurses from the University of Alabama at Birmingham (UAB) Hospital working night shift ( n = 9; 29.6 ± 11.4 y) and day shift ( n = 8; 34.9 ± 9.4 y) participated in a 9-day study measuring locomotor activity and core body temperature (CBT) continuously. Additionally, cortisol and melatonin were assayed and peripheral blood mononuclear cells (PBMCs) were harvested for RNA extraction every 3 h on a day off from work...
February 4, 2019: Journal of Biological Rhythms
Gabriele M Berberich, Martin B Berberich, Aaron M Ellison, Arne Grumpe, Christian Wöhler
In situ activity patterns of 2 Formica rufa-group species ( F. pratensis; F. polyctena) were continuously studied at 4 different red wood-ant nests for 6 months in each of the years 2010, 2011, 2012, and 2016 and related to weather factors and variations in the Earth's magnetic field. The in situ activity patterns of both species were similarly periodic and exhibited ultradian, and short- and long infradian rhythms under natural LD conditions. Crepuscular and nocturnal activities shorter than or equal to 4 h were observed in both species, especially at the new moon and first quarter after the astronomical twilight in a period of darkness in fall...
February 2019: Journal of Biological Rhythms
Carmel Bilu, Paul Zimmet, Vicktoria Vishnevskia-Dai, Haim Einat, Galila Agam, Ehud Grossman, Noga Kronfeld-Schor
Although type 2 diabetes (T2DM) and depression are associated with disturbances in circadian rhythms, most studies of these diseases use nocturnal mice and rats while modeling diurnal humans. We suggest that the development of T2DM and depression are related to changes that accompany the switch from the mammalian ancestral nocturnal activity to the current diurnal one. We show that diurnal sand rats ( Psammomys obesus) held outdoors in laboratory cages (where they are exposed to natural environmental conditions) and fed a standard rodent diet do not develop T2DM in contrast to animals held indoors (where the only cycling environmental condition is light) fed the same diet...
February 2019: Journal of Biological Rhythms
Maxine P Bonham, Elleni Kaias, Iona Zimberg, Gloria K W Leung, Rochelle Davis, Tracey L Sletten, Hazel Windsor-Aubrey, Catherine E Huggins
Eating at night time, as is frequent in shift workers, may contribute to increased cardiovascular disease (CVD) risk through a disruption in usual lipid metabolism, resulting in repeated and sustained hyperlipidemia at night. This systematic review aimed to investigate the impact of eating a meal at night compared with the same meal eaten during the day on postprandial lipemia. Six databases were searched: CINAHL Plus, Cochrane Library, EMBASE, Ovid MEDLINE, Informit, and SCOPUS. Eligible studies were original research cross-over design with a minimum fasting period of 5 h before testing preceded by a standardized control meal; measured postprandial triacylglycerol (TAG) for 5 h or greater; had meal time between 0700 h and 1600 h for day time and between 2000 h and 0400 h for night time; and had within-study test meals (food or drink) that were identical in macronutrient composition and energy...
January 25, 2019: Journal of Biological Rhythms
J Manuel Herrera-Zamora, Luis A Castro-Sánchez, Miriam Reyes-Mendez, Irving Aguilar-Martinez, Fernando Osuna-López, Eloy G Moreno-Galindo, Ricardo A Navarro-Polanco, Raul A Aguilar-Roblero, Enrique Sánchez-Pastor, Javier Alamilla
The suprachiasmatic nucleus (SCN) is the main brain clock that regulates circadian rhythms in mammals. The SCN synchronizes to the LD cycle through the retinohypothalamic tract (RHT), which projects to ventral SCN neurons via glutamatergic synapses. Released glutamate activates N-methyl-D-aspartate (NMDA) receptors, which play a critical role in the activation of signaling cascades to enable phase shifts. Previous evidence indicates that presynaptic changes during postnatal development consist of an increase in RHT fibers impinging on SCN neurons between postnatal day (P) 1 to 4 and P15...
January 17, 2019: Journal of Biological Rhythms
Laura Kervezee, Marc Cuesta, Nicolas Cermakian, Diane B Boivin
Light is a potent synchronizer of the central circadian clock; however, the effect of light exposure on peripheral gene expression is largely unknown. The objective of this study was to explore the effect of bright light exposure on genome-wide peripheral gene expression levels during a 4-day simulated night shift protocol in which the habitual sleep period is delayed by 10 h. Eleven healthy participants (mean age, 24 years; range, 18-30; 10 men/1 woman) were studied under controlled laboratory conditions. Three participants were exposed to bright light (~6,500 lux) for 8 h during the nightly waking period, while the other 8 were maintained in dim-light conditions (~10 lux)...
January 8, 2019: Journal of Biological Rhythms
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