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Journal of Biological Rhythms

Ricardo Laranjeiro, T Katherine Tamai, William Letton, Noémie Hamilton, David Whitmore
Studies from a number of model systems have shown that the circadian clock controls expression of key cell cycle checkpoints, thus providing permissive or inhibitory windows in which specific cell cycle events can occur. However, a major question remains: Is the clock actually regulating the cell cycle through such a gating mechanism or, alternatively, is there a coupling process that controls the speed of cell cycle progression? Using our light-responsive zebrafish cell lines, we address this issue directly by synchronizing the cell cycle in culture simply by changing the entraining light-dark (LD) cycle in the incubator without the need for pharmacological intervention...
February 1, 2018: Journal of Biological Rhythms
Dóra Nagy, Gabriele Andreatta, Stefano Bastianello, Ane Martín Anduaga, Gabriella Mazzotta, Charalambos P Kyriacou, Rodolfo Costa
The fruit fly Drosophila melanogaster survives thermally stressful conditions in a state of reproductive dormancy (diapause), manifested by reduced metabolic activity and arrested ovarian development in females. Unlike insects that rely primarily on photoperiodic stimuli to initiate the diapause program, in this species dormancy is regulated by low temperature and enhanced by shorter photoperiods. Overwintering phenotypes are usually studied under simple laboratory conditions, where animals are exposed to rectangular light-dark (LD) cycles at a constant temperature...
February 1, 2018: Journal of Biological Rhythms
Seth D Rhoades, Katrina Nayak, Shirley Zhang, Amita Sehgal, Aalim M Weljie
Complex interactions of environmental cues and transcriptional clocks drive rhythmicity in organismal physiology. Light directly affects the circadian clock; however, little is known about its relative role in controlling metabolic variations in vivo. Here we used high time-resolution sampling in Drosophila at every 2 h to measure metabolite outputs using a liquid-chromatography tandem mass spectrometry (LC-MS/MS) approach. Over 14% of detected metabolites oscillated with circadian periodicity under light-dark (LD) cycles...
January 1, 2018: Journal of Biological Rhythms
Shan Chen, Kevin K Fuller, Jay C Dunlap, Jennifer J Loros
Circadian rhythms govern immune cell function, giving rise to time-of-day variation in the recognition and clearance of bacterial or viral pathogens; to date, however, no such regulation of the host-fungal interaction has been described. In this report, we use murine models to explore circadian control of either fungal-macrophage interactions in vitro or pathogen clearance from the lung in vivo. First, we show that expression of the important fungal pattern recognition receptor Dectin-1 ( clec7a), from either bone marrow-derived or peritoneum-derived macrophages, is not under circadian regulation at either the level of transcript or cell surface protein expression...
December 1, 2017: Journal of Biological Rhythms
Toru Matsu-Ura, Sean R Moore, Christian I Hong
Like two dancers, the circadian clock and cell cycle are biological oscillators engaged in bidirectional communication, resulting in circadian clock-gated cell division cycles in species ranging from cyanobacteria to mammals. The identified mechanisms for this phenomenon have expanded beyond intracellular molecular coupling components to include intercellular connections. However, detailed molecular mechanisms, dynamics, and physiological functions of the circadian clock and cell cycle as coupled oscillators remain largely unknown...
December 1, 2017: Journal of Biological Rhythms
Natalie Niepoth, Gao Ke, Jacobus C de Roode, Astrid T Groot
Circadian behavior is widely observed in insects; however, the mechanisms that drive its evolution remain a black box. While circadian activity rhythms are well characterized in adults within the order Lepidoptera (i.e., most butterfly species are day active, while most moths are night active), much less is known about daily activity and clock gene expression in the larval stage. Additionally, direct comparison of clock gene expression between day-active and night-active species reared together has not been quantified...
December 1, 2017: Journal of Biological Rhythms
Kelly Glazer Baron, Kathryn J Reid, Lisa F Wolfe, Hrayr Attarian, Phyllis C Zee
Circadian misalignment is hypothesized to contribute to increased diabetes and obesity among shift workers and individuals with late sleep timing. Accordingly, the goal of our study was to identify-among normal and overweight/obese adults-associations between circadian timing (dim light melatonin onset; DLMO) and circadian misalignment (the interval between DLMO and sleep onset) with metabolic disease risk. This was a secondary analysis of data from a larger study. Participants ages 18 to 50 years without depression, diabetes, or shift work, with sleep duration 6...
December 1, 2017: Journal of Biological Rhythms
Christoph Schmal, Erik D Herzog, Hanspeter Herzel
Modern imaging techniques allow the monitoring of circadian rhythms of single cells. Coupling between these single cellular circadian oscillators can generate coherent periodic signals on the tissue level that subsequently orchestrate physiological outputs. The strength of coupling in such systems of oscillators is often unclear. In particular, effects on coupling strength by varying cell densities, by knockouts, and by inhibitor applications are debated. In this study, we suggest to quantify the relative coupling strength via analyzing period, phase, and amplitude distributions in ensembles of individual circadian oscillators...
December 1, 2017: Journal of Biological Rhythms
Juan Cheng, Xu Huang, Yue Liang, Tian Xue, Liecheng Wang, Jin Bao
Neurons in the suprachiasmatic nucleus (SCN) exhibit circadian variation in their neuronal activities. Here, we show that their input synapses undergo daily regulation. We discovered daily variation in the frequencies, but not the peak amplitudes, of miniature postsynaptic currents (mPSCs) for both glutamatergic and GABAergic synapses. In addition, the changes in the frequencies of mPSCs from glutamatergic and GABAergic synapses were antiphasic: An increase in the glutamatergic mPSC frequency and a decrease in the GABAergic mPSC frequency co-occurred during the dark phase of the light-dark cycle...
February 2018: Journal of Biological Rhythms
William J Schwartz
No abstract text is available yet for this article.
December 2017: Journal of Biological Rhythms
Valeria Zonato, Stefano Vanin, Rodolfo Costa, Eran Tauber, Charalambos P Kyriacou
The spread of adaptive genetic variants in populations is a cornerstone of evolutionary theory but with relatively few biologically well-understood examples. Previous work on the ls-tim variant of timeless, which encodes the light-sensitive circadian regulator in Drosophila melanogaster, suggests that it may have originated in southeastern Italy. Flies characterized by the new allele show photoperiod-related phenotypes likely to be adaptive in seasonal environments. ls-tim may be spreading from its point of origin in Italy by directional selection, but there are alternative explanations for its observed clinal geographical distribution, including balancing selection and demography...
November 1, 2017: Journal of Biological Rhythms
Kwangwon Lee, Prithvi Shiva Kumar, Sean McQuade, Joshua Y Lee, Sohyun Park, Zheming An, Benedetto Piccoli
Circadian rhythms are observed in most organisms on earth and are known to play a major role in successful adaptation to the 24-h cycling environment. Circadian phenotypes are characterized by a free-running period that is observed in constant conditions and an entrained phase that is observed in cyclic conditions. Thus, the relationship between the free-running period and phase of entrainment is of interest. A popular simple rule has been that the entrained phase is the expression of the period in a cycling environment (i...
November 1, 2017: Journal of Biological Rhythms
Julia Gestrich, Maria Giese, Wen Shen, Yi Zhang, Alexandra Voss, Cyril Popov, Monika Stengl, HongYing Wei
Transplantation studies have pinpointed the circadian clock of the Madeira cockroach to the accessory medulla (AME) of the brain's optic lobes. The AME is innervated by approximately 240 adjacent neuropeptidergic neurons, including 12 pigment-dispersing factor (PDF)-expressing neurons anterior to the AME (aPDFMEs). Four of the aPDFMEs project contralaterally, controlling locomotor activity rhythms of the night-active cockroach. The present in vitro Ca2+ imaging analysis focuses on contralaterally projecting AME neurons and their responses to PDF, GABA, and acetylcholine (ACh)...
November 1, 2017: Journal of Biological Rhythms
Christa Kistenpfennig, Mayumi Nakayama, Ruri Nihara, Kenji Tomioka, Charlotte Helfrich-Förster, Taishi Yoshii
In many animals, the circadian clock plays a role in adapting to the coming season by measuring day length. The mechanism for measuring day length and its neuronal circuits remains elusive, however. Under laboratory conditions, the fruit fly, Drosophila melanogaster, displays 2 activity peaks: one in the morning and one in the evening. These peaks appear to be regulated by 2 separate circadian oscillators (the morning and evening oscillators) that reside in different subsets of pacemaker clock neurons in the brain...
November 1, 2017: Journal of Biological Rhythms
Louise L Hansen, Harrold A van den Burg, Gerben van Ooijen
The transcriptional circadian clock network is tuned into a 24-h oscillator by numerous posttranslational modifications on the proteins encoded by clock genes, differentially influencing their subcellular localization or activity. Clock proteins in any circadian organism are subject to posttranslational regulation, and many of the key enzymes, notably kinases and phosphatases, are functionally conserved between the clocks of mammals, fungi, and plants. We now establish sumoylation, the posttranslational modification of target proteins by the covalent attachment of the small ubiquitin-like modifier protein SUMO, as a novel mechanism regulating key clock properties in the model plant Arabidopsis...
November 1, 2017: Journal of Biological Rhythms
Olivia M Nippe, Alex R Wade, Christopher J H Elliott, Sangeeta Chawla
An organism's biological day is characterized by a pattern of anticipatory physiological and behavioral changes that are governed by circadian clocks to align with the 24-h cycling environment. Here, we used flash electroretinograms (ERGs) and steady-state visually evoked potentials (SSVEPs) to examine how visual responsiveness in wild-type Drosophila melanogaster and the circadian clock mutant ClkJrk varies over circadian time. We show that the ERG parameters of wild-type flies vary over the circadian day, with a higher luminance response during the subjective night...
November 1, 2017: Journal of Biological Rhythms
Louise L Hansen, Lisa Imrie, Thierry Le Bihan, Harrold A van den Burg, Gerben van Ooijen
In plants, the circadian clock regulates the expression of one-third of all transcripts and is crucial to virtually every aspect of metabolism and growth. We now establish sumoylation, a posttranslational protein modification, as a novel regulator of the key clock protein CCA1 in the model plant Arabidopsis. Dynamic sumoylation of CCA1 is observed in planta and confirmed in a heterologous expression system. To characterize how sumoylation might affect the activity of CCA1, we investigated the properties of CCA1 in a wild-type plant background in comparison with ots1 ots2, a mutant background showing increased overall levels of sumoylation...
November 1, 2017: Journal of Biological Rhythms
Phan Q Duy, Samer Hattar
Artificial light in modern society has led to the ubiquity of light exposure at night as individuals work night shifts and use light-emitting electronic devices before bedtime. These aberrant light conditions have detrimental consequences on cognitive and mental health, compelling the need to understand the mechanisms by which light affects brain functions. Although it was believed that aberrant light impairs health by first disrupting circadian rhythms and sleep, we showed that chronic exposure to a light cycle termed T7 (3...
November 1, 2017: Journal of Biological Rhythms
William J Schwartz
No abstract text is available yet for this article.
October 2017: Journal of Biological Rhythms
Michael E Hughes, Katherine C Abruzzi, Ravi Allada, Ron Anafi, Alaaddin Bulak Arpat, Gad Asher, Pierre Baldi, Charissa de Bekker, Deborah Bell-Pedersen, Justin Blau, Steve Brown, M Fernanda Ceriani, Zheng Chen, Joanna C Chiu, Juergen Cox, Alexander M Crowell, Jason P DeBruyne, Derk-Jan Dijk, Luciano DiTacchio, Francis J Doyle, Giles E Duffield, Jay C Dunlap, Kristin Eckel-Mahan, Karyn A Esser, Garret A FitzGerald, Daniel B Forger, Lauren J Francey, Ying-Hui Fu, Frédéric Gachon, David Gatfield, Paul de Goede, Susan S Golden, Carla Green, John Harer, Stacey Harmer, Jeff Haspel, Michael H Hastings, Hanspeter Herzel, Erik D Herzog, Christy Hoffmann, Christian Hong, Jacob J Hughey, Jennifer M Hurley, Horacio O de la Iglesia, Carl Johnson, Steve A Kay, Nobuya Koike, Karl Kornacker, Achim Kramer, Katja Lamia, Tanya Leise, Scott A Lewis, Jiajia Li, Xiaodong Li, Andrew C Liu, Jennifer J Loros, Tami A Martino, Jerome S Menet, Martha Merrow, Andrew J Millar, Todd Mockler, Felix Naef, Emi Nagoshi, Michael N Nitabach, Maria Olmedo, Dmitri A Nusinow, Louis J Ptáček, David Rand, Akhilesh B Reddy, Maria S Robles, Till Roenneberg, Michael Rosbash, Marc D Ruben, Samuel S C Rund, Aziz Sancar, Paolo Sassone-Corsi, Amita Sehgal, Scott Sherrill-Mix, Debra J Skene, Kai-Florian Storch, Joseph S Takahashi, Hiroki R Ueda, Han Wang, Charles Weitz, Pål O Westermark, Herman Wijnen, Ying Xu, Gang Wu, Seung-Hee Yoo, Michael Young, Eric Erquan Zhang, Tomasz Zielinski, John B Hogenesch
Genome biology approaches have made enormous contributions to our understanding of biological rhythms, particularly in identifying outputs of the clock, including RNAs, proteins, and metabolites, whose abundance oscillates throughout the day. These methods hold significant promise for future discovery, particularly when combined with computational modeling. However, genome-scale experiments are costly and laborious, yielding "big data" that are conceptually and statistically difficult to analyze. There is no obvious consensus regarding design or analysis...
October 2017: Journal of Biological Rhythms
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