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Sample records for machinery underlying circadian

  1. Machinery

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ China Council for the Promotion of International Trade, Machin-ery Sub-Council (referred to as CCPIT MSC) & China Chamber of International Commerce, Machinery Chamber of Commerce was founded in 1988 as one of the first group of industrial trade promotion agencies approved by the governing authorities of China.

  2. On the mechanochemical machinery underlying chromatin remodeling

    Science.gov (United States)

    Yusufaly, Tahir I.

    This dissertation discuss two recent efforts, via a unique combination of structural bioinformatics and density functional theory, to unravel some of the details concerning how molecular machinery within the eukaryotic cell nucleus controls chromatin architecture. The first, a study of the 5-methylation of cytosine in 5'-CG-3' : 5'-CG-3' base-pair steps, reveals that the methyl groups roughen the local elastic energy landscape of the DNA. This enhances the probability of the canonical B-DNA structure transitioning into the undertwisted A-like and overtwisted C-like forms seen in nucleosomes, or looped segments of DNA bound to histones. The second part focuses on the formation of salt bridges between arginine residues in histones and phosphate groups on the DNA backbone. The arginine residues are ob- served to apply a tunable mechanical load to the backbone, enabling precision-controlled activation of DNA deformations.

  3. Photoperiodic diapause under the control of circadian clock genes in an insect

    Directory of Open Access Journals (Sweden)

    Ikeno Tomoko

    2010-09-01

    Full Text Available Abstract Background Most organisms have evolved a circadian clock in order to anticipate daily environmental changes and many of these organisms are also capable of sophisticated measurement of daylength (photoperiodism that is used to regulate seasonal events such as diapause, migration and polymorphism. It has been generally accepted that the same elements are involved in both circadian (daily and seasonal (annual rhythms because both rely upon daily light-dark cycles. However, as reasonable as this sounds, there remains no conclusive evidence of such a molecular machinery in insects. We have approached this issue by using RNA interference (RNAi in Riptortus pedestris. Results The cuticle deposition rhythm exhibited the major properties of circadian rhythms, indicating that the rhythm is regulated by a circadian clock. RNAi directed against the circadian clock genes of period and cycle, which are negative and positive regulators in the circadian clock, respectively, disrupted the cuticle deposition rhythm and distinct cuticle layers were produced by these RNAi. Simultaneously, period RNAi caused the insect to avert diapause under a diapause-inducing photoperiod whereas cycle RNAi induced diapause under a diapause-averting photoperiod. The expression patterns of juvenile hormone-regulated genes and the application of juvenile hormone analogue suggested that neither ovarian development itself nor a downstream cascade of juvenile hormone secretion, were disturbed by period and cycle RNAi. Conclusions This study revealed that the circadian clock genes are crucial not only for daily rhythms but also for photoperiodic diapause. RNAi directed against period and cycle had opposite effects not only in the circadian cuticle deposition rhythm but also in the photoperiodic diapause. These RNAi also had opposite effects on juvenile hormone-regulated gene expression. It is still possible that the circadian clock genes pleiotropically affect ovarian

  4. Molecular Mechanisms Underlying the Arabidopsis Circadian Clock

    OpenAIRE

    Nakamichi, Norihito

    2011-01-01

    A wide range of biological processes exhibit circadian rhythm, enabling plants to adapt to the environmental day–night cycle. This rhythm is generated by the so-called ‘circadian clock’. Although a number of genetic approaches have identified >25 clock-associated genes involved in the Arabidopsis clock mechanism, the molecular functions of a large part of these genes are not known. Recent comprehensive studies have revealed the molecular functions of several key clock-associated proteins. Thi...

  5. Molecular mechanisms underlying the Arabidopsis circadian clock.

    Science.gov (United States)

    Nakamichi, Norihito

    2011-10-01

    A wide range of biological processes exhibit circadian rhythm, enabling plants to adapt to the environmental day-night cycle. This rhythm is generated by the so-called 'circadian clock'. Although a number of genetic approaches have identified >25 clock-associated genes involved in the Arabidopsis clock mechanism, the molecular functions of a large part of these genes are not known. Recent comprehensive studies have revealed the molecular functions of several key clock-associated proteins. This progress has provided mechanistic insights into how key clock-associated proteins are integrated, and may help in understanding the essence of the clock's molecular mechanisms.

  6. Brief introduction of under- stage machinery (continued)%舞台下部机械(续)

    Institute of Scientific and Technical Information of China (English)

    宋宏

    2003-01-01

    It briefly introduces the use of typical under- stage machinery such as stage lifts, stage wagons and turntables in theater. It summarizes the functions,characteristics and drive modes of each type of under -stage machinery at present time.

  7. Individual differences in circadian waveform of Siberian hamsters under multiple lighting conditions.

    Science.gov (United States)

    Evans, Jennifer A; Elliott, Jeffrey A; Gorman, Michael R

    2012-10-01

    Because the circadian clock in the mammalian brain derives from a network of interacting cellular oscillators, characterizing the nature and bases of circadian coupling is fundamental to understanding how the pacemaker operates. Various phenomena involving plasticity in circadian waveform have been theorized to reflect changes in oscillator coupling; however, it remains unclear whether these different behavioral paradigms reference a unitary underlying process. To test whether disparate coupling assays index a common mechanism, we examined whether there is covariation among behavioral responses to various lighting conditions that produce changes in circadian waveform. Siberian hamsters, Phodopus sungorus, were transferred from long to short photoperiods to distinguish short photoperiod responders (SP-R) from nonresponders (SP-NR). Short photoperiod chronotyped hamsters were subsequently transferred, along with unselected controls, to 24-h light:dark:light: dark cycles (LDLD) with dim nighttime illumination, a procedure that induces bifurcated entrainment. Under LDLD, SP-R hamsters were more likely to bifurcate their rhythms than were SP-NR hamsters or unselected controls. After transfer from LDLD to constant dim light, SP-R hamsters were also more likely to become arrhythmic compared to SP-NR hamsters and unselected controls. In contrast, short photoperiod chronotype did not influence more transient changes in circadian waveform. The present data reveal a clear relationship in the plasticity of circadian waveform across 3 distinct lighting conditions, suggesting a common mechanism wherein individual differences reflect variation in circadian coupling.

  8. Social interaction and sex differences influence rat temperature circadian rhythm under LD cycles and constant light.

    Science.gov (United States)

    Cambras, T; Castejón, L; Díez-Noguera, A

    2011-06-01

    Circadian rhythms produce an efficient organization of animal behaviour over the 24h day. In some species, social cues have been found to have a role as synchronizers of these rhythms. Here, the influence of social interaction on rat circadian behaviour was investigated, addressing the question of whether cohabitation would produce a delay in the appearance of arrhythmicity under constant light conditions. To this end, the circadian rhythms of male and female rat body temperature were studied for 10days under light-dark conditions, followed by 33days under constant bright light. Half of the animals were maintained in individual cages, whilst the others were maintained in larger cages in groups of three rats of the same sex. Results showed that individual circadian rhythms under 24hour light-dark (LD) cycles were more stable and with higher amplitude in grouped than in isolated animals, and higher in males than in females. During the first days under constant light (LL), the stability of the rhythm was also higher in males than in females, but there were no differences according to the group. Moreover, we did not find significant differences in the time of circadian rhythm loss under LL, since high individual variability was found for this variable. On the other hand, female rats living in isolation showed a delayed acrophase in the circadian rhythm under LD conditions compared with those living in groups. These results suggest that cohabitation increases the internal coherence of circadian behaviour, and could be interpreted as indicating that living in isolation may induce a level of stress that disturbs manifestation of the circadian rhythm, especially in females, which are also more reactive than males to external signals.

  9. China Cancels 23 Textile Machinery Commodities under Automatic Import Licensing Administration

    Institute of Scientific and Technical Information of China (English)

    Zheng Yan

    2007-01-01

    @@ In accordance with Measures for Administration on Commodities of Automatic Import Licensing, Ministry of Commerce adjusted List of Commodities under Automatic Import Licensing Administration of 2007, on March 10, canceling automatic import licensing administration of 338 tax items including 23 textile machinery commodities.

  10. Research progress and prospects on machinery monitoring under varying working condition

    Institute of Scientific and Technical Information of China (English)

    Lin Jing; Zhao Ming

    2013-01-01

    A general review is given about the research progress of the rotating machinery condition monitoring under varying working condition.The major typical methods for analyzing are reviewed,including their progress,deficiencies and capabilities.Some prospects are given finally.

  11. Circadian oscillation of the lettuce transcriptome under constant light and light–dark conditions

    Directory of Open Access Journals (Sweden)

    Takanobu Higashi

    2016-07-01

    Full Text Available Although the circadian clock is a universal biological system in plants and it orchestrates important role of plant production such as photosynthesis, floral induction and growth, there are few such studies on cultivated species. Lettuce is one major cultivated species for both open culture and plant factories and there is little information concerning its circadian clock system. In addition, most of the relevant genes have not been identified. In this study, we detected circadian oscillation in the lettuce transcriptome using time-course RNA sequencing (RNA-Seq data. Constant light (LL and light–dark (LD conditions were used to detect circadian oscillation because the circadian clock has some basic properties: one is self-sustaining oscillation under constant light and another is entrainment to environmental cycles such as light and temperature. In the results, 215 contigs were detected as common oscillating contigs under both LL and LD conditions. The 215 common oscillating contigs included clock gene-like contigs CCA1 (CIRCADIAN CLOCK ASSOCIATED 1-like, TOC1 (TIMING OF CAB EXPRESSION 1-like and LHY (LATE ELONGATED HYPOCOTYL-like, and their expression patterns were similar to those of Arabidopsis. Functional enrichment analysis by GO (Gene Ontology Slim and GO Fat showed that the GO terms of response to light stimulus, response to stress, photosynthesis and circadian rhythms were enriched in the 215 common oscillating contigs and these terms were actually regulated by circadian clocks in plants. The 215 common oscillating contigs can be used to evaluate whether the gene expression pattern related to photosynthesis and optical response performs normally in lettuce.

  12. Research on Approximate Calculation of Preventive Maintenance Period in Machinery Systems under Random Distribution

    Institute of Scientific and Technical Information of China (English)

    WU Bo; CHEN Gang; JIANG Zhengfeng; ZHENG Junyi

    2006-01-01

    Approximate calculation methods of prevention maintenance period under the random distribution are given, and three kinds of approximate calculation models of prevention maintenance period based on different security demands are come up with according to maintenance problems of machinery systems in modern enterprise and starting with different demands of systems. And then, how to make certain the best maintenance period by using the approximate calculation methods is illustrated by an example.

  13. Circadian rhythms in the cell cycle and biomass composition of Neochloris oleoabundans under nitrogen limitation.

    Science.gov (United States)

    de Winter, Lenneke; Schepers, Lutz W; Cuaresma, Maria; Barbosa, Maria J; Martens, Dirk E; Wijffels, René H

    2014-10-10

    The circadian clock schedules processes in microalgae cells at suitable times in the day/night cycle. To gain knowledge about these biological time schedules, Neochloris oleoabundans was grown under constant light conditions and nitrogen limitation. Under these constant conditions, the only variable was the circadian clock. The results were compared to previous work done under nitrogen-replete conditions, in order to determine the effect of N-limitation on circadian rhythms in the cell cycle and biomass composition of N. oleoabundans. The circadian clock was not affected by nitrogen-limitation, and cell division was timed in the natural night, despite of constant light conditions. However, because of nitrogen-limitation, not the entire population was able to divide every day. Two subpopulations were observed, which divided alternately every other day. This caused oscillations in biomass yield and composition. Starch and total fatty acids (TFA) were accumulated during the day. Also, fatty acid composition changed during the cell cycle. Neutral lipids were built up during the day, especially in cells that were arrested in their cell cycle (G2 and G3). These findings give insight in the influence of circadian rhythms on the cell cycle and biomass composition.

  14. Synchrony of plant cellular circadian clocks with heterogeneous properties under light/dark cycles.

    Science.gov (United States)

    Okada, Masaaki; Muranaka, Tomoaki; Ito, Shogo; Oyama, Tokitaka

    2017-03-22

    Individual cells in a plant can work independently as circadian clocks, and their properties are the basis of various circadian phenomena. The behaviour of individual cellular clocks in Lemna gibba was orderly under 24-h light/dark cycles despite their heterogeneous free-running periods (FRPs). Here, we reveal the entrainment habits of heterogeneous cellular clocks using non-24-h light/dark cycles (T-cycles). The cellular rhythms of AtCCA1::LUC under T = 16 h cycles showed heterogeneous entrainment that was associated with their heterogeneous FRPs. Under T = 12 h cycles, most cells showed rhythms having ~24-h periods. This suggested that the lower limit of entrainment to the light/dark cycles of heterogeneous cellular circadian clocks is set to a period longer than 12 h, which enables them to be synchronous under ~24-h daily cycles without being perturbed by short light/dark cycles. The entrainment habits of individual cellular clocks are likely to be the basis of the circadian behaviour of plant under the natural day-night cycle with noisy environmental fluctuations. We further suggest that modifications of EARLY FLOWERING3 (ELF3) in individual cells deviate the entrainability to shorter T-cycles possibly by altering both the FRPs and light responsiveness.

  15. Molecular Mechanisms of Circadian Regulation During Spaceflight

    Science.gov (United States)

    Zanello, S. B.; Boyle, R.

    2012-01-01

    The physiology of both vertebrates and invertebrates follows internal rhythms coordinated in phase with the 24-hour daily light cycle. This circadian clock is governed by a central pacemaker, the suprachiasmatic nucleus (SCN) in the brain. However, peripheral circadian clocks or oscillators have been identified in most tissues. How the central and peripheral oscillators are synchronized is still being elucidated. Light is the main environmental cue that entrains the circadian clock. Under the absence of a light stimulus, the clock continues its oscillation in a free-running condition. In general, three functional compartments of the circadian clock are defined. The vertebrate retina contains endogenous clocks that control many aspects of retinal physiology, including retinal sensitivity to light, neurohormone synthesis (melatonin and dopamine), rod disk shedding, signalling pathways and gene expression. Neurons with putative local circadian rhythm generation are found among all the major neuron populations in the mammalian retina. In the mouse, clock genes and function are more localized to the inner retinal and ganglion cell layers. The photoreceptor, however, secrete melatonin which may still serve a an important circadian signal. The reception and transmission of the non-visual photic stimulus resides in a small subpopulation (1-3%) or retinal ganglion cells (RGC) that express the pigment melanopsin (Opn4) and are called intrisically photoreceptive RGC (ipRGC). Melanopsin peak absorption is at 420 nm and all the axons of the ipRGC reach the SCN. A common countermeasure for circadian re-entrainment utilizes blue-green light to entrain the circadian clock and mitigate the risk of fatigue and health and performance decrement due to circadian rhythm disruption. However, an effective countermeasure targeting the photoreceptor system requires that the basic circadian molecular machinery remains intact during spaceflight. We hypothesize that spaceflight may affect ip

  16. Food-entrained feeding and locomotor circadian rhythms in rats under different lighting conditions.

    Science.gov (United States)

    Lax, P; Zamora, S; Madrid, J A

    1999-05-01

    It has been suggested that two endogenous timekeeping systems, a light-entrainable pacemaker (LEP) and a food-entrainable pacemaker (FEP), control circadian rhythms. To understand the function and interaction between these two mechanisms better, we studied two behavioral circadian rhythmicities, feeding and locomotor activity, in rats exposed to two conflicting zeitgebers, food restriction and light-dark cycles. For this, the food approaches and wheel-running activity of rats kept under light-dark (LD) 12:12, constant darkness (DD), or constant light (LL) conditions and subjected to different scheduled feeding patterns were continuously recorded. To facilitate comparison of the results obtained under the different lighting conditions, the period of the feeding cycles was set in all three cases about 1h less than the light-entrained or free-running circadian rhythms. The results showed that, depending on the lighting conditions, some components of the feeding and wheel-running circadian rhythms could be entrained by food pulses, while others retained their free-running or light-entrained state. Under LD, food pulses had little influence on the light-entrained feeding and locomotor rhythms. Under DD, relative coordination between free-running and food-associated rhythms may appear. In both cases, the feeding activity associated with the food pulses could be divided into a prominent phase-dependent peak of activity within the period of food availability and another afterward. Wheel-running activity mainly followed the food pulses. Under LL conditions, the food-entrained activity consisted mainly of feeding and wheel-running anticipatory activity. The results provide new evidence that lighting conditions influence the establishment and persistence of food-entrained circadian rhythms in rats. The existence of two coupled pacemakers, LEP and FEP, or a multioscillatory LEP may both explain our experimental results.

  17. Insulin Signaling Misregulation underlies Circadian and Cognitive Deficits in a Drosophila Fragile X Model

    Science.gov (United States)

    Monyak, Rachel E.; Emerson, Danielle; Schoenfeld, Brian P.; Zheng, Xiangzhong; Chambers, Daniel B.; Rosenfelt, Cory; Langer, Steven; Hinchey, Paul; Choi, Catherine H.; McDonald, Thomas V.; Bolduc, Francois V.; Sehgal, Amita; McBride, Sean M.J.; Jongens, Thomas A.

    2016-01-01

    Fragile X syndrome (FXS) is an undertreated neurodevelopmental disorder characterized by low IQ and a wide range of other symptoms including disordered sleep and autism. Although FXS is the most prevalent inherited cause of intellectual disability, its mechanistic underpinnings are not well understood. Using Drosophila as a model of FXS, we showed that select expression of dfmr1 in the insulin-producing cells (IPCs) of the brain was sufficient to restore normal circadian behavior and to rescue the memory deficits in the fragile X mutant fly. Examination of the insulin-signaling (IS) pathway revealed elevated levels of Drosophila insulin-like peptide 2 (Dilp2) in the IPCs and elevated IS in the dfmr1 mutant brain. Consistent with a causal role for elevated IS in dfmr1 mutant phenotypes, expression of dfmr1 specifically in the IPCs reduced IS, and genetic reduction of the insulin pathway also led to amelioration of circadian and memory defects. Furthermore we showed that treatment with the FDA approved drug metformin also rescued memory. Finally, we showed that reduction of IS is required at different time points to rescue circadian behavior and memory. Our results indicate that insulin misregulation underlies the circadian and cognitive phenotypes displayed by the Drosophila fragile X model, and thus reveal a metabolic pathway that can be targeted by new and already approved drugs to treat fragile X patients. PMID:27090306

  18. A self-regulatory circuit of CIRCADIAN CLOCK-ASSOCIATED1 underlies the circadian clock regulation of temperature responses in Arabidopsis.

    Science.gov (United States)

    Seo, Pil Joon; Park, Mi-Jeong; Lim, Mi-Hye; Kim, Sang-Gyu; Lee, Minyoung; Baldwin, Ian T; Park, Chung-Mo

    2012-06-01

    The circadian clock synchronizes biological processes to daily cycles of light and temperature. Clock components, including CIRCADIAN CLOCK-ASSOCIATED1 (CCA1), are also associated with cold acclimation. However, it is unknown how CCA1 activity is modulated in coordinating circadian rhythms and cold acclimation. Here, we report that self-regulation of Arabidopsis thaliana CCA1 activity by a splice variant, CCA1β, links the clock to cold acclimation. CCA1β interferes with the formation of CCA1α-CCA1α and LATE ELONGATED HYPOCOTYL (LHY)-LHY homodimers, as well as CCA1α-LHY heterodimers, by forming nonfunctional heterodimers with reduced DNA binding affinity. Accordingly, the periods of circadian rhythms were shortened in CCA1β-overexpressing transgenic plants (35S:CCA1β), as observed in the cca1 lhy double mutant. In addition, the elongated hypocotyl and leaf petiole phenotypes of CCA1α-overexpressing transgenic plants (35S:CCA1α) were repressed by CCA1β coexpression. Notably, low temperatures suppressed CCA1 alternative splicing and thus reduced CCA1β production. Consequently, whereas the 35S:CCA1α transgenic plants exhibited enhanced freezing tolerance, the 35S:CCA1β transgenic plants were sensitive to freezing, indicating that cold regulation of CCA1 alternative splicing contributes to freezing tolerance. On the basis of these findings, we propose that dynamic self-regulation of CCA1 underlies the clock regulation of temperature responses in Arabidopsis.

  19. Heterogeneity of cellular circadian clocks in intact plants and its correction under light-dark cycles.

    Science.gov (United States)

    Muranaka, Tomoaki; Oyama, Tokitaka

    2016-07-01

    Recent advances in single-cell analysis have revealed the stochasticity and nongenetic heterogeneity inherent to cellular processes. However, our knowledge of the actual cellular behaviors in a living multicellular organism is still limited. By using a single-cell bioluminescence imaging technique on duckweed, Lemna gibba, we demonstrate that, under constant conditions, cells in the intact plant work as individual circadian clocks that oscillate with their own frequencies and respond independently to external stimuli. Quantitative analysis uncovered the heterogeneity and instability of cellular clocks and partial synchronization between neighboring cells. Furthermore, we found that cellular clocks in the plant body under light-dark cycles showed a centrifugal phase pattern in which the effect of cell-to-cell heterogeneity in period lengths was almost masked. The inherent heterogeneity in the properties of cellular clocks observed under constant conditions is corrected under light-dark cycles to coordinate the daily rhythms of the plant body. These findings provide a novel perspective of spatiotemporal architectures in the plant circadian system.

  20. Age-related changes in sleep and circadian rhythms: impact on cognitive performance and underlying neuroanatomical networks

    Directory of Open Access Journals (Sweden)

    Christina eSchmidt

    2012-07-01

    Full Text Available Circadian and homeostatic sleep-wake regulatory processes interact in a fine tuned manner to modulate human cognitive performance. Dampening of the circadian alertness signal and attenuated deterioration of psychomotor vigilance in response to elevated sleep pressure with aging change this interaction pattern. As evidenced by neuroimaging studies, both homeostatic sleep pressure and circadian sleep-wake promotion impact on cognition-related cortical and arousal-promoting subcortical brain regions including the thalamus, the anterior hypothalamus and the brainstem locus coeruleus (LC. However, how age- related changes in circadian and homeostatic processes impact on the cerebral activity subtending waking performance remains largely unexplored. Post-mortem studies point to neuronal degeneration in the SCN and age-related modifications to aging in the arousal-promoting LC. Alongside, cortical frontal brain areas are particularly susceptible both to aging and misalignment between circadian and homeostatic processes. In this perspective, we summarise and discuss here the potential neuroanatomical networks underlying age-related changes in circadian and homeostatic modulation of waking performance, ranging from basic arousal to higher order cognitive behaviours.

  1. Circadian gating of the cell cycle revealed in single cyanobacterial cells.

    Science.gov (United States)

    Yang, Qiong; Pando, Bernardo F; Dong, Guogang; Golden, Susan S; van Oudenaarden, Alexander

    2010-03-19

    Although major progress has been made in uncovering the machinery that underlies individual biological clocks, much less is known about how multiple clocks coordinate their oscillations. We simultaneously tracked cell division events and circadian phases of individual cells of the cyanobacterium Synechococcus elongatus and fit the data to a model to determine when cell cycle progression slows as a function of circadian and cell cycle phases. We infer that cell cycle progression in cyanobacteria slows during a specific circadian interval but is uniform across cell cycle phases. Our model is applicable to the quantification of the coupling between biological oscillators in other organisms.

  2. The relative contributions of the homeostatic and circadian processes to sleep regulation under conditions of severe sleep restriction.

    Science.gov (United States)

    Paech, Gemma M; Ferguson, Sally A; Sargent, Charli; Kennaway, David J; Roach, Gregory D

    2012-07-01

    To investigate the relative contributions of the homeostatic and circadian processes on sleep regulation under conditions of severe sleep restriction. The 13-day laboratory based study consisted of 3 × 24-h baseline days (8 h sleep opportunity, 16 h wake) followed by 7 × 28-h forced desynchrony days (4.7 h sleep opportunity, 23.3 h wake). The study was conducted in a time isolation unit at the Centre for Sleep Research, University of South Australia. Fourteen healthy, nonsmoking males, aged 21.8 ± 3.8 (mean ± SD) years participated in the study. N/A. Sleep was measured using standard polysomnography. Core body temperature (CBT) was recorded continuously using a rectal thermistor. Each epoch of sleep was assigned a circadian phase based on the CBT data (6 × 60-degree bins) and an elapsed time into sleep episode (2 × 140-min intervals). The percentage of SWS decreased with elapsed time into the sleep episode. However, no change in the percentage of REM sleep was observed with sleep progression. Whilst there was a circadian modulation of REM sleep, the amplitude of the circadian variation was smaller than expected. Sleep efficiency remained high throughout the sleep episode and across all circadian phases. Previous forced desynchrony studies have demonstrated a strong circadian influence on sleep, in the absence of sleep restriction. The current study suggests that in the presence of high homeostatic pressure, the circadian modulation of sleep, in particular sleep efficiency and to a lesser extent, REM sleep, are reduced.

  3. Interrelations and circadian changes of electroencephalogram frequencies under baseline conditions and constant sleep pressure in the rat.

    Science.gov (United States)

    Yasenkov, R; Deboer, T

    2011-04-28

    Similar to the nap-protocols applied in humans, the repeated short-sleep deprivation protocol in rats stabilizes slow-wave activity (SWA, 0.5-4 Hz) in the non-rapid eye movement (NREM) sleep electroencephalogram (EEG), thus reflecting a constant sleep pressure or sleep homeostatic level, whereas higher frequencies (7-25 Hz) in these conditions preserve their daily rhythm, therefore demonstrating a strong input from an endogenous circadian clock. How different EEG frequencies in rapid eye movement (REM) sleep and waking respond to these constant conditions, how they interrelate to each other within the different vigilance states, and which component of sleep regulation (homeostatic or circadian) is involved, remain unknown. To answer these questions, we applied power spectral analysis and correlation analysis to 1 Hz bin EEG frequency data for different vigilance states in freely moving rats in constant darkness, under baseline conditions and during the repeated short-sleep deprivation protocol. Our analysis suggests that (1) 0.5-5 Hz frequencies in NREM sleep and higher frequencies in REM sleep (above 19 Hz) and waking (above 10 Hz) are sleep-dependent, and thus seem to be under control of the sleep homeostat, while (2) faster frequencies in the NREM sleep EEG (7-25 Hz) and 3-7 Hz activity in the REM sleep EEG are under strong influence of the endogenous circadian clock. Theta activity in waking (5-7 Hz) seems to reflect both circadian and behavior dependent influences. NREM sleep EEG frequencies between 9 and 14 Hz showed both homeostatic and circadian components in their behavior. Thus, frequencies in the EEG of the different vigilance states seem to represent circadian and homeostatic components of sleep regulatory mechanisms, where REM sleep and waking frequency ranges behave similarly to each other and differently from NREM sleep frequencies.

  4. A Neural Network Underlying Circadian Entrainment and Photoperiodic Adjustment of Sleep and Activity in Drosophila

    NARCIS (Netherlands)

    Schlichting, Matthias; Menegazzi, Pamela; Lelito, Katharine R.; Yao, Zepeng; Buhl, Edgar; Dalla Benetta, Elena; Bahle, Andrew; Denike, Jennifer; Hodge, James John; Helfrich-Förster, Charlotte; Shafer, Orie Thomas

    2016-01-01

    A sensitivity of the circadian clock to light/dark cycles ensures that biological rhythms maintain optimal phase relationships with the external day. In animals, the circadian clock neuron network (CCNN) driving sleep/activity rhythms receives light input from multiple photoreceptors, but how these

  5. Postnatal constant light compensates Cryptochrome1 and 2 double deficiency for disruption of circadian behavioral rhythms in mice under constant dark.

    Directory of Open Access Journals (Sweden)

    Daisuke Ono

    Full Text Available Clock genes Cryptochrome (Cry1 and Cry2 are essential for expression of circadian rhythms in mice under constant darkness (DD. However, circadian rhythms in clock gene Per1 expression or clock protein PER2 are detected in the cultured suprachiasmatic nucleus (SCN of neonatal Cry1 and Cry2 double deficient (Cry1 (-/-/Cry2 (-/- mice. A lack of circadian rhythms in adult Cry1 (-/-/Cry2 (-/- mice is most likely due to developmentally disorganized cellular coupling of oscillating neurons in the SCN. On the other hand, neonatal rats exposed to constant light (LL developed a tenable circadian system under prolonged LL which was known to fragment circadian behavioral rhythms. In the present study, Cry1 (-/-/Cry2 (-/- mice were raised under LL from postnatal day 1 for 7 weeks and subsequently exposed to DD for 3 weeks. Spontaneous movement was monitored continuously after weaning and PER2::LUC was measured in the cultured SCN obtained from mice under prolonged DD. Surprisingly, Chi square periodogram analysis revealed significant circadian rhythms of spontaneous movement in the LL-raised Cry1 (-/-/Cry2 (-/- mice, but failed to detect the rhythms in Cry1 (-/-/Cry2 (-/- mice raised under light-dark cycles (LD. By contrast, prolonged LL in adulthood did not rescue the circadian behavioral rhythms in the LD raised Cry1 (-/-/Cry2 (-/- mice. Visual inspection disclosed two distinct activity components with different periods in behavioral rhythms of the LL-raised Cry1(-/-/Cry2(-/- mice under DD: one was shorter and the other was longer than 24 hours. The two components repeatedly merged and separated. The patterns resembled the split behavioral rhythms of wild type mice under prolonged LL. In addition, circadian rhythms in PER2::LUC were detected in some of the LL-raised Cry1(-/-/Cry2(-/- mice under DD. These results indicate that neonatal exposure to LL compensates the CRY double deficiency for the disruption of circadian behavioral rhythms under DD in

  6. Circadian metabolism in the light of evolution.

    Science.gov (United States)

    Gerhart-Hines, Zachary; Lazar, Mitchell A

    2015-06-01

    Circadian rhythm, or daily oscillation, of behaviors and biological processes is a fundamental feature of mammalian physiology that has developed over hundreds of thousands of years under the continuous evolutionary pressure of energy conservation and efficiency. Evolution has fine-tuned the body's clock to anticipate and respond to numerous environmental cues in order to maintain homeostatic balance and promote survival. However, we now live in a society in which these classic circadian entrainment stimuli have been dramatically altered from the conditions under which the clock machinery was originally set. A bombardment of artificial lighting, heating, and cooling systems that maintain constant ambient temperature; sedentary lifestyle; and the availability of inexpensive, high-calorie foods has threatened even the most powerful and ancient circadian programming mechanisms. Such environmental changes have contributed to the recent staggering elevation in lifestyle-influenced pathologies, including cancer, cardiovascular disease, depression, obesity, and diabetes. This review scrutinizes the role of the body's internal clocks in the hard-wiring of circadian networks that have evolved to achieve energetic balance and adaptability, and it discusses potential therapeutic strategies to reset clock metabolic control to modern time for the benefit of human health.

  7. Circadian Rhythms

    Science.gov (United States)

    ... microbes. The study of circadian rhythms is called chronobiology. Are circadian rhythms the same thing as biological ... the eyes cross. Do circadian rhythms have a genetic component? Yes. Researchers have already identified genes that ...

  8. Recovery from Age-Related Infertility under Environmental Light-Dark Cycles Adjusted to the Intrinsic Circadian Period

    OpenAIRE

    Nana N. Takasu; Takahiro J. Nakamura; Isao T. Tokuda; Takeshi Todo; Gene D. Block; Wataru Nakamura

    2015-01-01

    © 2015 The Authors. Female reproductive function changes during aging with the estrous cycle becoming more irregular during the transition to menopause. We found that intermittent shifts of the light-dark cycle disrupted regularity of estrous cycles in middle-aged female mice, whose estrous cycles were regular under unperturbed 24-hr light-dark cycles. Although female mice deficient in Cry1 or Cry2, the core components of the molecular circadian clock, exhibited regular estrous cycles during ...

  9. Circadian entrainment of Neurospora crassa

    NARCIS (Netherlands)

    Merrow, M.; Roenneberg, T.

    2007-01-01

    The circadian clock evolved under entraining conditions, yet most circadian experiments and much circadian theory are built around free-running rhythms. The interpretation of entrainment experiments is certainly more complex than that of free-running rhythms due to the relationship between exogenous

  10. Evidence for Weakened Intercellular Coupling in the Mammalian Circadian Clock under Long Photoperiod

    Science.gov (United States)

    Buijink, M. Renate; Almog, Assaf; Wit, Charlotte B.; Roethler, Ori; Olde Engberink, Anneke H. O.; Meijer, Johanna H.; Garlaschelli, Diego; Rohling, Jos H. T.; Michel, Stephan

    2016-01-01

    For animals living in temperate latitudes, seasonal changes in day length are an important cue for adaptations of their physiology and behavior to the altered environmental conditions. The suprachiasmatic nucleus (SCN) is known as the central circadian clock in mammals, but may also play an important role in adaptations to different photoperiods. The SCN receives direct light input from the retina and is able to encode day-length by approximating the waveform of the electrical activity rhythm to the duration of daylight. Changing the overall waveform requires a reorganization of the neuronal network within the SCN with a change in the degree of synchrony between the neurons; however, the underlying mechanisms are yet unknown. In the present study we used PER2::LUC bioluminescence imaging in cultured SCN slices to characterize network dynamics on the single-cell level and we aimed to provide evidence for a role of modulations in coupling strength in the photoperiodic-induced phase dispersal. Exposure to long photoperiod (LP) induced a larger distribution of peak times of the single-cell PER2::LUC rhythms in the anterior SCN, compared to short photoperiod. Interestingly, the cycle-to-cycle variability in single-cell period of PER2::LUC rhythms is also higher in the anterior SCN in LP, and is positively correlated with peak time dispersal. Applying a new, impartial community detection method on the time series data of the PER2::LUC rhythm revealed two clusters of cells with a specific spatial distribution, which we define as dorsolateral and ventromedial SCN. Post hoc analysis of rhythm characteristics of these clusters showed larger cycle-to-cycle single-cell period variability in the dorsolateral compared to the ventromedial cluster in the anterior SCN. We conclude that a change in coupling strength within the SCN network is a plausible explanation to the observed changes in single-cell period variability, which can contribute to the photoperiod-induced phase

  11. Accuracy of circadian entrainment under fluctuating light conditions : Contributions of phase and period responses

    NARCIS (Netherlands)

    Beersma, DGM; Daan, S; Hut, RA

    1999-01-01

    The accuracy with which a circadian pacemaker can entrain to an environmental 24-h zeitgeber signal depends on (a) characteristics of the entraining signal and (b) response characteristics and intrinsic stability of the pacemaker itself. Position of the sun, weather conditions, shades, and behaviora

  12. The Drosophila melanogaster circadian pacemaker circuit

    Indian Academy of Sciences (India)

    Vasu Sheeba

    2008-12-01

    As an experimental model system, the fruit fly Drosophila melanogaster has been seminal in shaping our understanding of the circadian clockwork. The wealth of genetic tools at our disposal over the past four decades has enabled discovery of the genetic and molecular bases of circadian rhythmicity. More recently, detailed investigation leading to the anatomical, neurochemical and electrophysiological characterization of the various neuronal subgroups that comprise the circadian machinery has revealed pathways through which these neurons come together to act as a neuronal circuit. Thus the D. melanogaster circadian pacemaker circuit presents a relatively simple and attractive model for the study of neuronal circuits and their functions.

  13. Circadian regulation of food-anticipatory activity in molecular clock-deficient mice.

    Directory of Open Access Journals (Sweden)

    Nana N Takasu

    Full Text Available In the mammalian brain, the suprachiasmatic nucleus (SCN of the anterior hypothalamus is considered to be the principal circadian pacemaker, keeping the rhythm of most physiological and behavioral processes on the basis of light/dark cycles. Because restriction of food availability to a certain time of day elicits anticipatory behavior even after ablation of the SCN, such behavior has been assumed to be under the control of another circadian oscillator. According to recent studies, however, mutant mice lacking circadian clock function exhibit normal food-anticipatory activity (FAA, a daily increase in locomotor activity preceding periodic feeding, suggesting that FAA is independent of the known circadian oscillator. To investigate the molecular basis of FAA, we examined oscillatory properties in mice lacking molecular clock components. Mice with SCN lesions or with mutant circadian periods were exposed to restricted feeding schedules at periods within and outside circadian range. Periodic feeding led to the entrainment of FAA rhythms only within a limited circadian range. Cry1(-/- mice, which are known to be a "short-period mutant," entrained to a shorter period of feeding cycles than did Cry2(-/- mice. This result indicated that the intrinsic periods of FAA rhythms are also affected by Cry deficiency. Bmal1(-/- mice, deficient in another essential element of the molecular clock machinery, exhibited a pre-feeding increase of activity far from circadian range, indicating a deficit in circadian oscillation. We propose that mice possess a food-entrainable pacemaker outside the SCN in which canonical clock genes such as Cry1, Cry2 and Bmal1 play essential roles in regulating FAA in a circadian oscillatory manner.

  14. Circadian regulation of food-anticipatory activity in molecular clock-deficient mice.

    Science.gov (United States)

    Takasu, Nana N; Kurosawa, Gen; Tokuda, Isao T; Mochizuki, Atsushi; Todo, Takeshi; Nakamura, Wataru

    2012-01-01

    In the mammalian brain, the suprachiasmatic nucleus (SCN) of the anterior hypothalamus is considered to be the principal circadian pacemaker, keeping the rhythm of most physiological and behavioral processes on the basis of light/dark cycles. Because restriction of food availability to a certain time of day elicits anticipatory behavior even after ablation of the SCN, such behavior has been assumed to be under the control of another circadian oscillator. According to recent studies, however, mutant mice lacking circadian clock function exhibit normal food-anticipatory activity (FAA), a daily increase in locomotor activity preceding periodic feeding, suggesting that FAA is independent of the known circadian oscillator. To investigate the molecular basis of FAA, we examined oscillatory properties in mice lacking molecular clock components. Mice with SCN lesions or with mutant circadian periods were exposed to restricted feeding schedules at periods within and outside circadian range. Periodic feeding led to the entrainment of FAA rhythms only within a limited circadian range. Cry1(-/-) mice, which are known to be a "short-period mutant," entrained to a shorter period of feeding cycles than did Cry2(-/-) mice. This result indicated that the intrinsic periods of FAA rhythms are also affected by Cry deficiency. Bmal1(-/-) mice, deficient in another essential element of the molecular clock machinery, exhibited a pre-feeding increase of activity far from circadian range, indicating a deficit in circadian oscillation. We propose that mice possess a food-entrainable pacemaker outside the SCN in which canonical clock genes such as Cry1, Cry2 and Bmal1 play essential roles in regulating FAA in a circadian oscillatory manner.

  15. Is vertical migration in Antarctic krill (Euphausia superba) influenced by an underlying circadian rhythm?

    Indian Academy of Sciences (India)

    Edward Gaten; Geraint Tarling; Harold Dowse; Charalambos Kyriacou; Ezio Rosato

    2008-12-01

    Antarctic krill (Euphausia superba) is a keystone species in the southern ocean ecosystem where it is the main consumer of phytoplankton and constitutes the main food item of many higher predators. Both food and predators are most abundant at the surface, thus krill hide in the depth of the ocean during the day and migrate to the upper layers at night, to feed at a time when the predatory risk is lowest. Although the functional significance of this diel vertical migration (DVM) is clear and its modulation by environmental factors has been described, the involvement of an endogenous circadian clock in this behaviour is as yet not fully resolved. We have analysed the circadian behaviour of Euphausia superba in a laboratory setting and here we present the first description of locomotor activity rhythms for this species. Our results are in agreement with the hypothesis that the circadian clock plays a key role in DVM. They also suggest that the interplay between food availability, social cues and the light:dark cycle acts as the predominant Zeitgeber for DVM in this species.

  16. Entrainment of mouse peripheral circadian clocks to cycles under 24 h light/dark conditions.

    Science.gov (United States)

    Hamaguchi, Yutaro; Tahara, Yu; Kuroda, Hiroaki; Haraguchi, Atsushi; Shibata, Shigenobu

    2015-09-23

    The circadian clock system in peripheral tissues can endogenously oscillate and is entrained by the light-dark and fasting-feeding cycles in mammals. Although the system's range of entrainment to light-dark cycles with a non-24 h (cycles with shorter periods (cycle (Tau (T) = 15-24 h) under normal light-dark conditions. Peripheral clocks could be entrained to the feeding cycle with T = 22-24 h, but not to that with T = 15-21 h. Under the feeding cycle with T = 15-18 h, the peripheral clocks oscillated at near the 24-h period, suggesting that they were entrained to the light-dark cycle. Thus, for the first time, we demonstrated the range of entrainment to the non-24 h feeding cycle, and that the circadian range (T = 22-24 h) of feeding stimulus is necessary for peripheral molecular clock entrainment under light-dark cycles.

  17. Effects of simulated microgravity on circadian rhythm of caudal arterial pressure and heart rate in rats and their underlying mechanism

    Directory of Open Access Journals (Sweden)

    Li CHEN

    2016-04-01

    Full Text Available Objective  To explore the effects of simulated microgravity on the circadian rhythm of rats' caudal arterial pressure and heart rate, and their underlying mechanism. Methods  Eighteen male SD rats (aged 8 weeks were randomly assigned to control (CON and tail suspension (SUS group (9 each. Rats with tail suspension for 28 days were adopted as the animal model to simulate microgravity. Caudal arterial pressure and heart rate of rats were measured every 3 hours. The circadian difference of abdominal aorta contraction was measured by aortic ring test. Western blotting was performed to determine and compare the protein expression level of clock genes such as Per2 (Period2, Bmal1 (Aryl hydrocarbon receptor nuclear translocatorlike and dbp (D element binding protein in suprachiasmatic nucleus (SCN and abdominal aorta of rats in CON and SUS group at different time points. Results  Compared with CON group, the caudal arterial pressure, both systolic and diastolic pressure, decreased significantly and the diurnal variability disappeared, meanwhile the heart rate increased obviously and also the diurnal variability disappeared in rats of SUS group. Compared with CON group, the contraction reactivity of abdominal aorta decreased with disappearence of the diurnal variability, and also the clock genes expression in SCN and abdominal aorta showed no diurnal variability in rats of SUS group. Conclusion  Simulated microgravity may lead to circadian rhythm disorders in rats' cardiovascular system, which may be associated with the changes of the clock genes expression. DOI: 10.11855/j.issn.0577-7402.2016.04.06

  18. HvLUX1 is a candidate gene underlying the early maturity 10 locus in barley: phylogeny, diversity, and interactions with the circadian clock and photoperiodic pathways.

    Science.gov (United States)

    Campoli, Chiara; Pankin, Artem; Drosse, Benedikt; Casao, Cristina M; Davis, Seth J; von Korff, Maria

    2013-09-01

    Photoperiodic flowering is a major factor determining crop performance and is controlled by interactions between environmental signals and the circadian clock. We proposed Hvlux1, an ortholog of the Arabidopsis circadian gene LUX ARRHYTHMO, as a candidate underlying the early maturity 10 (eam10) locus in barley (Hordeum vulgare L.). The link between eam10 and Hvlux1 was discovered using high-throughput sequencing of enriched libraries and segregation analysis. We conducted functional, phylogenetic, and diversity studies of eam10 and HvLUX1 to understand the genetic control of photoperiod response in barley and to characterize the evolution of LUX-like genes within barley and across monocots and eudicots. We demonstrate that eam10 causes circadian defects and interacts with the photoperiod response gene Ppd-H1 to accelerate flowering under long and short days. The results of phylogenetic and diversity analyses indicate that HvLUX1 was under purifying selection, duplicated at the base of the grass clade, and diverged independently of LUX-like genes in other plant lineages. Taken together, these findings contribute to improved understanding of the barley circadian clock, its interaction with the photoperiod pathway, and evolution of circadian systems in barley and across monocots and eudicots.

  19. Recovery from Age-Related Infertility under Environmental Light-Dark Cycles Adjusted to the Intrinsic Circadian Period

    Directory of Open Access Journals (Sweden)

    Nana N. Takasu

    2015-09-01

    Full Text Available Female reproductive function changes during aging with the estrous cycle becoming more irregular during the transition to menopause. We found that intermittent shifts of the light-dark cycle disrupted regularity of estrous cycles in middle-aged female mice, whose estrous cycles were regular under unperturbed 24-hr light-dark cycles. Although female mice deficient in Cry1 or Cry2, the core components of the molecular circadian clock, exhibited regular estrous cycles during youth, they showed accelerated senescence characterized by irregular and unstable estrous cycles and resultant infertility in middle age. Notably, tuning the period length of the environmental light-dark cycles closely to the endogenous one inherent in the Cry-deficient females restored the regularity of the estrous cycles and, consequently, improved fertility in middle age. These results suggest that reproductive potential can be strongly influenced by age-related changes in the circadian system and normal reproductive functioning can be rescued by the manipulation of environmental timing signals.

  20. Circadian rhythms in the growth and reproduction of the brown alga Undaria pinnatifida and gametogenesis under different photoperiods

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhihuai; PANG Shaojun

    2007-01-01

    Circadian growth rhythm of the juvenile sporophyte of the brown alga Undaria pinnatifida was measured with the computer-aided image analysis system in constant florescent white light under constant temperature ( 10 ℃ ). The growth rhythm persisted for 4 d in constant light with a free-running period of 25.6 h. Egg release from filamentous gametophytes pre-cultured in the light - dark regime was evaluated for six consecutive days at fixed time intervals in constant white light and 12 h light per day. Egg release rhythm persisted for 3 d in both regimes, indicating the endogenous nature. Temporal scale of egg release and gametogenesis in 18, 16, 12 and 8 h light per day were evaluated respectively using vegetatively propagated filamentous gametophytes. Egg release occurred 2 h after the onset of dark phase and peaked at midnight. Evaluation of the rates of oogonium formation, egg release or fertilization revealed no significant differences in four light-dark regimes, indicating the great plasticity of sexual reproduction. No photoperiodic effect in gametogenesis in terms of oogonium formation and egg release was found, but fertilization in short days was significantly higher than in long days. Results of this investigation further confirmed the general occurrence of circadian rhythms in intertidal seaweed species.

  1. Recovery from Age-Related Infertility under Environmental Light-Dark Cycles Adjusted to the Intrinsic Circadian Period.

    Science.gov (United States)

    Takasu, Nana N; Nakamura, Takahiro J; Tokuda, Isao T; Todo, Takeshi; Block, Gene D; Nakamura, Wataru

    2015-09-01

    Female reproductive function changes during aging with the estrous cycle becoming more irregular during the transition to menopause. We found that intermittent shifts of the light-dark cycle disrupted regularity of estrous cycles in middle-aged female mice, whose estrous cycles were regular under unperturbed 24-hr light-dark cycles. Although female mice deficient in Cry1 or Cry2, the core components of the molecular circadian clock, exhibited regular estrous cycles during youth, they showed accelerated senescence characterized by irregular and unstable estrous cycles and resultant infertility in middle age. Notably, tuning the period length of the environmental light-dark cycles closely to the endogenous one inherent in the Cry-deficient females restored the regularity of the estrous cycles and, consequently, improved fertility in middle age. These results suggest that reproductive potential can be strongly influenced by age-related changes in the circadian system and normal reproductive functioning can be rescued by the manipulation of environmental timing signals.

  2. 新形势下做好农机管理工作的策略研究%Study on Management Strategy for Farm Machinery Under New Situations

    Institute of Scientific and Technical Information of China (English)

    刀宏应

    2014-01-01

    Under the new situation, the mechanization of agriculture has become important measures to adjust the a-gricultural structure, and is the main trend in the future development of agricultural production. in view of this, farm ma-chinery management work should be brought on the desk. This paper analyzes the situation of the current agricultural ma-chinery management, and gives a certain optimization strategy to agricultural machinery management work, which is to further improve and boost the development of agricultural machinery management.%在新形势下,农机化发展已成为调整农业结构的重要措施,也是未来农业生产发展的主要趋势,因此对于农机管理工作应该重点探讨。论文从当前农机管理工作的现状问题出发进行分析,提出了农机管理工作的不足,并对此相应的提出一定的优化策略,力求进一步做好农机管理工作,促进农机管理的进步发展。

  3. Alternative splicing and nonsense-mediated decay of circadian clock genes under environmental stress conditions in Arabidopsis.

    Science.gov (United States)

    Kwon, Young-Ju; Park, Mi-Jeong; Kim, Sang-Gyu; Baldwin, Ian T; Park, Chung-Mo

    2014-05-19

    The circadian clock enables living organisms to anticipate recurring daily and seasonal fluctuations in their growth habitats and synchronize their biology to the environmental cycle. The plant circadian clock consists of multiple transcription-translation feedback loops that are entrained by environmental signals, such as light and temperature. In recent years, alternative splicing emerges as an important molecular mechanism that modulates the clock function in plants. Several clock genes are known to undergo alternative splicing in response to changes in environmental conditions, suggesting that the clock function is intimately associated with environmental responses via the alternative splicing of the clock genes. However, the alternative splicing events of the clock genes have not been studied at the molecular level. We systematically examined whether major clock genes undergo alternative splicing under various environmental conditions in Arabidopsis. We also investigated the fates of the RNA splice variants of the clock genes. It was found that the clock genes, including EARLY FLOWERING 3 (ELF3) and ZEITLUPE (ZTL) that have not been studied in terms of alternative splicing, undergo extensive alternative splicing through diverse modes of splicing events, such as intron retention, exon skipping, and selection of alternative 5' splice site. Their alternative splicing patterns were differentially influenced by changes in photoperiod, temperature extremes, and salt stress. Notably, the RNA splice variants of TIMING OF CAB EXPRESSION 1 (TOC1) and ELF3 were degraded through the nonsense-mediated decay (NMD) pathway, whereas those of other clock genes were insensitive to NMD. Taken together, our observations demonstrate that the major clock genes examined undergo extensive alternative splicing under various environmental conditions, suggesting that alternative splicing is a molecular scheme that underlies the linkage between the clock and environmental stress

  4. A circadian clock in Saccharomyces cerevisiae

    NARCIS (Netherlands)

    Eelderink-Chen, Zheng; Mazzotta, Gabriella; Sturre, Marcel; Bosman, Jasper; Roenneberg, Till; Merrow, Martha

    2010-01-01

    Circadian timing is a fundamental biological process, underlying cellular physiology in animals, plants, fungi, and cyanobacteria. Circadian clocks organize gene expression, metabolism, and behavior such that they occur at specific times of day. The biological clocks that orchestrate these daily

  5. A Novel Bmal1 Mutant Mouse Reveals Essential Roles of the C-Terminal Domain on Circadian Rhythms.

    Science.gov (United States)

    Park, Noheon; Kim, Hee-Dae; Cheon, Solmi; Row, Hansang; Lee, Jiyeon; Han, Dong-Hee; Cho, Sehyung; Kim, Kyungjin

    2015-01-01

    The mammalian circadian clock is an endogenous biological timer comprised of transcriptional/translational feedback loops of clock genes. Bmal1 encodes an indispensable transcription factor for the generation of circadian rhythms. Here, we report a new circadian mutant mouse from gene-trapped embryonic stem cells harboring a C-terminus truncated Bmal1 (Bmal1GTΔC) allele. The homozygous mutant (Bmal1GTΔC/GTΔC) mice immediately lost circadian behavioral rhythms under constant darkness. The heterozygous (Bmal1+/GTΔC) mice displayed a gradual loss of rhythms, in contrast to Bmal1+/- mice where rhythms were sustained. Bmal1GTΔC/GTΔC mice also showed arrhythmic mRNA and protein expression in the SCN and liver. Lack of circadian reporter oscillation was also observed in cultured fibroblast cells, indicating that the arrhythmicity of Bmal1GTΔC/GTΔC mice resulted from impaired molecular clock machinery. Expression of clock genes exhibited distinct responses to the mutant allele in Bmal1+/GTΔC and Bmal1GTΔC/GTΔC mice. Despite normal cellular localization and heterodimerization with CLOCK, overexpressed BMAL1GTΔC was unable to activate transcription of Per1 promoter and BMAL1-dependent CLOCK degradation. These results indicate that the C-terminal region of Bmal1 has pivotal roles in the regulation of circadian rhythms and the Bmal1GTΔC mice constitute a novel model system to evaluate circadian functional mechanism of BMAL1.

  6. Light and the circadian clock mediate time-specific changes in sensitivity to UV-B stress under light/dark cycles.

    Science.gov (United States)

    Takeuchi, Tomomi; Newton, Linsey; Burkhardt, Alyssa; Mason, Saundra; Farré, Eva M

    2014-11-01

    In Arabidopsis, the circadian clock regulates UV-B-mediated changes in gene expression. Here it is shown that circadian clock components are able to inhibit UV-B-induced gene expression in a gene-by-gene-specific manner and act downstream of the initial UV-B sensing by COP1 (CONSTITUTIVE PHOTOMORPHOGENIC 1) and UVR8 (UV RESISTANCE LOCUS 8). For example, the UV-B induction of ELIP1 (EARLY LIGHT INDUCIBLE PROTEIN 1) and PRR9 (PSEUDO-RESPONSE REGULATOR 9) is directly regulated by LUX (LUX ARRYTHMO), ELF4 (EARLY FLOWERING 4), and ELF3. Moreover, time-dependent changes in plant sensitivity to UV-B damage were observed. Wild-type Arabidopsis plants, but not circadian clock mutants, were more sensitive to UV-B treatment during the night periods than during the light periods under diel cycles. Experiments performed under short cycles of 6h light and 6h darkness showed that the increased stress sensitivity of plants to UV-B in the dark only occurred during the subjective night and not during the subjective day in wild-type seedlings. In contrast, the stress sensitivity of Arabidopsis mutants with a compromised circadian clock was still influenced by the light condition during the subjective day. Taken together, the results show that the clock and light modulate plant sensitivity to UV-B stress at different times of the day.

  7. Redox crisis underlies conditional light-dark lethality in cyanobacterial mutants that lack the circadian regulator, RpaA.

    Science.gov (United States)

    Diamond, Spencer; Rubin, Benjamin E; Shultzaberger, Ryan K; Chen, You; Barber, Chase D; Golden, Susan S

    2017-01-24

    Cyanobacteria evolved a robust circadian clock, which has a profound influence on fitness and metabolism under daily light-dark (LD) cycles. In the model cyanobacterium Synechococcus elongatus PCC 7942, a functional clock is not required for diurnal growth, but mutants defective for the response regulator that mediates transcriptional rhythms in the wild-type, regulator of phycobilisome association A (RpaA), cannot be cultured under LD conditions. We found that rpaA-null mutants are inviable after several hours in the dark and compared the metabolomes of wild-type and rpaA-null strains to identify the source of lethality. Here, we show that the wild-type metabolome is very stable throughout the night, and this stability is lost in the absence of RpaA. Additionally, an rpaA mutant accumulates excessive reactive oxygen species (ROS) during the day and is unable to clear it during the night. The rpaA-null metabolome indicates that these cells are reductant-starved in the dark, likely because enzymes of the primary nighttime NADPH-producing pathway are direct targets of RpaA. Because NADPH is required for processes that detoxify ROS, conditional LD lethality likely results from inability of the mutant to activate reductant-requiring pathways that detoxify ROS when photosynthesis is not active. We identified second-site mutations and growth conditions that suppress LD lethality in the mutant background that support these conclusions. These results provide a mechanistic explanation as to why rpaA-null mutants die in the dark, further connect the clock to metabolism under diurnal growth, and indicate that RpaA likely has important unidentified functions during the day.

  8. Circadian systems biology in Metazoa.

    Science.gov (United States)

    Lin, Li-Ling; Huang, Hsuan-Cheng; Juan, Hsueh-Fen

    2015-11-01

    Systems biology, which can be defined as integrative biology, comprises multistage processes that can be used to understand components of complex biological systems of living organisms and provides hierarchical information to decoding life. Using systems biology approaches such as genomics, transcriptomics and proteomics, it is now possible to delineate more complicated interactions between circadian control systems and diseases. The circadian rhythm is a multiscale phenomenon existing within the body that influences numerous physiological activities such as changes in gene expression, protein turnover, metabolism and human behavior. In this review, we describe the relationships between the circadian control system and its related genes or proteins, and circadian rhythm disorders in systems biology studies. To maintain and modulate circadian oscillation, cells possess elaborative feedback loops composed of circadian core proteins that regulate the expression of other genes through their transcriptional activities. The disruption of these rhythms has been reported to be associated with diseases such as arrhythmia, obesity, insulin resistance, carcinogenesis and disruptions in natural oscillations in the control of cell growth. This review demonstrates that lifestyle is considered as a fundamental factor that modifies circadian rhythm, and the development of dysfunctions and diseases could be regulated by an underlying expression network with multiple circadian-associated signals.

  9. 精确农业背景下我国农业机械发展趋势%The Tendency of China's Agricultural Machinery Development Under Precision Agriculture

    Institute of Scientific and Technical Information of China (English)

    段向敏; 代荣

    2013-01-01

    精确农业是世界农业发展的新潮流,是传统农业发展的必然趋势。为此,讲述了我国发展精确农业的必要性,并简单说明了国外智能农业机械的发展现状及趋势;分析了我国精确农业背景下的农业机械化发展存在的问题,对比国外精确农业的发展并结合我国基本国情,对我国新形势下的智能农业机械发展提出意见。%Precision agriculture is the latest trend in contemporary agriculture , precision agriculture also is the inevitable trend of the traditional agricultural .This paper chiefly tells about the necessity of developing precise agriculture in China and current situation and development trend of intelligent agricultural machinery in foreign countries .This paper analyzes the existing problems of developing agricultural mechanization under precision agriculture in China .Comparing with the development of precision agriculture in foreign countries , in addition , considering China ’ s fundamental condition , paper has put forward opinions to develop intelligent agricultural machinery under precise agriculture in China .

  10. Expressions of tight junction proteins Occludin and Claudin-1 are under the circadian control in the mouse large intestine: implications in intestinal permeability and susceptibility to colitis.

    Directory of Open Access Journals (Sweden)

    Oh-oka Kyoko

    Full Text Available BACKGROUND & AIMS: The circadian clock drives daily rhythms in behavior and physiology. A recent study suggests that intestinal permeability is also under control of the circadian clock. However, the precise mechanisms remain largely unknown. Because intestinal permeability depends on tight junction (TJ that regulates the epithelial paracellular pathway, this study investigated whether the circadian clock regulates the expression levels of TJ proteins in the intestine. METHODS: The expression levels of TJ proteins in the large intestinal epithelium and colonic permeability were analyzed every 4, 6, or 12 hours between wild-type mice and mice with a mutation of a key clock gene Period2 (Per2; mPer2(m/m. In addition, the susceptibility to dextran sodium sulfate (DSS-induced colitis was compared between wild-type mice and mPer2(m/m mice. RESULTS: The mRNA and protein expression levels of Occludin and Claudin-1 exhibited daily variations in the colonic epithelium in wild-type mice, whereas they were constitutively high in mPer2(m/m mice. Colonic permeability in wild-type mice exhibited daily variations, which was inversely associated with the expression levels of Occludin and Claudin-1 proteins, whereas it was constitutively low in mPer2(m/m mice. mPer2(m/m mice were more resistant to the colonic injury induced by DSS than wild-type mice. CONCLUSIONS: Occludin and Claudin-1 expressions in the large intestine are under the circadian control, which is associated with temporal regulation of colonic permeability and also susceptibility to colitis.

  11. Circadian modulation of sleep in rodents.

    Science.gov (United States)

    Yasenkov, Roman; Deboer, Tom

    2012-01-01

    Sleep is regulated by circadian and homeostatic processes. The sleep homeostat keeps track of the duration of prior sleep and waking and determines the intensity of sleep. In mammals, the homeostatic process is reflected by the slow waves in the non-rapid eye movement (NREM) sleep electroencephalogram (EEG). The circadian process is controlled by a pacemaker located in the suprachiasmatic nucleus of the hypothalamus and provides the sleep homeostat with a circadian framework. This review summarizes the changes in sleep obtained after different chronobiological interventions (changes in photoperiod, light availability, and running wheel availability), the influence of mutations or lesions in clock genes on sleep, and research on the interaction between sleep homeostasis and the circadian clock. Research in humans shows that the period of consolidated waking during the day is a consequence of the interaction between an increasing homeostatic sleep drive and a circadian signal, which promotes waking during the day and sleep during the night. In the rat, it was shown that, under constant homeostatic sleep pressure, with similar levels of slow waves in the NREM sleep EEG at all time points of the circadian cycle, still a small circadian modulation of the duration of waking and NREM sleep episodes was observed. Under similar conditions, humans show a clear circadian modulation in REM sleep, whereas in the rat, a circadian modulation in REM sleep was not present. Therefore, in the rat, the sleep homeostatic modulation in phase with the circadian clock seems to amplify the relatively weak circadian changes in sleep induced by the circadian clock. Knowledge about the interaction between sleep and the circadian clock and the circadian modulation of sleep in other species than humans is important to better understand the underlying regulatory mechanisms.

  12. [Current concepts of the origin of circadian changes in the cardiovascular system under normal and pathological conditions].

    Science.gov (United States)

    Arushanyan, E B

    2012-01-01

    The importance of circadian rhythms for the function of the cardiovascular system and its pharmacotherapy is discussed The central mechanisms regulating these rhythms at the level of suprachiasmatic hypothalamic nucleus and pineal gland are considered in conjunction with the approaches to modulating their activity for optimization of chronopharmnacotherapy of cardiovascular diseases.

  13. Circadian rhythms regulate amelogenesis.

    Science.gov (United States)

    Zheng, Li; Seon, Yoon Ji; Mourão, Marcio A; Schnell, Santiago; Kim, Doohak; Harada, Hidemitsu; Papagerakis, Silvana; Papagerakis, Petros

    2013-07-01

    Ameloblasts, the cells responsible for making enamel, modify their morphological features in response to specialized functions necessary for synchronized ameloblast differentiation and enamel formation. Secretory and maturation ameloblasts are characterized by the expression of stage-specific genes which follows strictly controlled repetitive patterns. Circadian rhythms are recognized as key regulators of the development and diseases of many tissues including bone. Our aim was to gain novel insights on the role of clock genes in enamel formation and to explore the potential links between circadian rhythms and amelogenesis. Our data shows definitive evidence that the main clock genes (Bmal1, Clock, Per1 and Per2) oscillate in ameloblasts at regular circadian (24 h) intervals both at RNA and protein levels. This study also reveals that the two markers of ameloblast differentiation i.e. amelogenin (Amelx; a marker of secretory stage ameloblasts) and kallikrein-related peptidase 4 (Klk4, a marker of maturation stage ameloblasts) are downstream targets of clock genes. Both, Amelx and Klk4 show 24h oscillatory expression patterns and their expression levels are up-regulated after Bmal1 over-expression in HAT-7 ameloblast cells. Taken together, these data suggest that both the secretory and the maturation stages of amelogenesis might be under circadian control. Changes in clock gene expression patterns might result in significant alterations of enamel apposition and mineralization.

  14. [Circadian rhythms in body temperature and sleep].

    Science.gov (United States)

    Honma, Ken-ichi

    2013-12-01

    A 24 hour variation of core body temperature in humans is primarily regulated by the endogenous circadian pacemaker located in the suprachiasmatic nucleus. And the expression of circadian rhythm is modified by the thermoregulatory mechanism controlling heat production and heat loss, which also show circadian rhythms. On the other hand, circadian rhythms in sleep-wakefulness are expressed by two independent but mutually coupled oscillators, the circadian pacemaker and the oscillator specific to sleep-wakefulness. However, neither the mechanism nor the site of oscillation of the latter is known. The time cues for these two oscillators are different. They are usually but frequently uncoupled under free-running conditions. Body temperature and sleep-wakefulness influence the counterpart in various extents, exerting masking effects on either circadian rhythm.

  15. A Novel Bmal1 Mutant Mouse Reveals Essential Roles of the C-Terminal Domain on Circadian Rhythms.

    Directory of Open Access Journals (Sweden)

    Noheon Park

    Full Text Available The mammalian circadian clock is an endogenous biological timer comprised of transcriptional/translational feedback loops of clock genes. Bmal1 encodes an indispensable transcription factor for the generation of circadian rhythms. Here, we report a new circadian mutant mouse from gene-trapped embryonic stem cells harboring a C-terminus truncated Bmal1 (Bmal1GTΔC allele. The homozygous mutant (Bmal1GTΔC/GTΔC mice immediately lost circadian behavioral rhythms under constant darkness. The heterozygous (Bmal1+/GTΔC mice displayed a gradual loss of rhythms, in contrast to Bmal1+/- mice where rhythms were sustained. Bmal1GTΔC/GTΔC mice also showed arrhythmic mRNA and protein expression in the SCN and liver. Lack of circadian reporter oscillation was also observed in cultured fibroblast cells, indicating that the arrhythmicity of Bmal1GTΔC/GTΔC mice resulted from impaired molecular clock machinery. Expression of clock genes exhibited distinct responses to the mutant allele in Bmal1+/GTΔC and Bmal1GTΔC/GTΔC mice. Despite normal cellular localization and heterodimerization with CLOCK, overexpressed BMAL1GTΔC was unable to activate transcription of Per1 promoter and BMAL1-dependent CLOCK degradation. These results indicate that the C-terminal region of Bmal1 has pivotal roles in the regulation of circadian rhythms and the Bmal1GTΔC mice constitute a novel model system to evaluate circadian functional mechanism of BMAL1.

  16. Cyclic electron flow provides acclimatory plasticity for the photosynthetic machinery under various environmental conditions and developmental stages

    Directory of Open Access Journals (Sweden)

    Marjaana eSuorsa

    2015-09-01

    Full Text Available Photosynthetic electron flow operates in two modes, linear and cyclic. In cyclic electron flow (CEF, electrons are recycled around photosystem I. As a result, a transthylakoid proton gradient (ΔpH is generated, leading to the production of ATP without concomitant production of NADPH, thus increasing the ATP/NADPH ratio within the chloroplast. At least two routes for CEF exist: a PGR5-PGRL1–and a chloroplast NDH-like complex mediated pathway. This review focuses on recent findings concerning the characteristics of both CEF routes in higher plants, with special emphasis paid on the crucial role of CEF in under challenging environmental conditions and developmental stages.

  17. Adaptation to experimental jet-lag in R6/2 mice despite circadian dysrhythmia.

    Directory of Open Access Journals (Sweden)

    Nigel I Wood

    Full Text Available The R6/2 transgenic mouse model of Huntington's disease (HD shows a disintegration of circadian rhythms that can be delayed by pharmacological and non-pharmacological means. Since the molecular machinery underlying the circadian clocks is intact, albeit progressively dysfunctional, we wondered if light phase shifts could modulate the deterioration in daily rhythms in R6/2 mice. Mice were subjected to four x 4 hour advances in light onset. R6/2 mice adapted to phase advances, although angles of entrainment increased with age. A second cohort was subjected to a jet-lag paradigm (6 hour delay or advance in light onset, then reversal after 2 weeks. R6/2 mice adapted to the original shift, but could not adjust accurately to the reversal. Interestingly, phase shifts ameliorated the circadian rhythm breakdown seen in R6/2 mice under normal LD conditions. Our previous finding that the circadian period (tau of 16 week old R6/2 mice shortens to approximately 23 hours may explain how they adapt to phase advances and maintain regular circadian rhythms. We tested this using a 23 hour period light/dark cycle. R6/2 mice entrained to this cycle, but onsets of activity continued to advance, and circadian rhythms still disintegrated. Therefore, the beneficial effects of phase-shifting are not due solely to the light cycle being closer to the tau of the mice. Our data show that R6/2 mice can adapt to changes in the LD schedule, even beyond the age when their circadian rhythms would normally disintegrate. Nevertheless, they show abnormal responses to changes in light cycles. These might be caused by a shortened tau, impaired photic re-synchronization, impaired light detection and/or reduced masking by evening light. If similar abnormalities are present in HD patients, they may suffer exaggerated jet-lag. Since the underlying molecular clock mechanism remains intact, light may be a useful treatment for circadian dysfunction in HD.

  18. Circadian clock feedback cycle through NAMPT-mediated NAD+ biosynthesis.

    Science.gov (United States)

    Ramsey, Kathryn Moynihan; Yoshino, Jun; Brace, Cynthia S; Abrassart, Dana; Kobayashi, Yumiko; Marcheva, Biliana; Hong, Hee-Kyung; Chong, Jason L; Buhr, Ethan D; Lee, Choogon; Takahashi, Joseph S; Imai, Shin-Ichiro; Bass, Joseph

    2009-05-01

    The circadian clock is encoded by a transcription-translation feedback loop that synchronizes behavior and metabolism with the light-dark cycle. Here we report that both the rate-limiting enzyme in mammalian nicotinamide adenine dinucleotide (NAD+) biosynthesis, nicotinamide phosphoribosyltransferase (NAMPT), and levels of NAD+ display circadian oscillations that are regulated by the core clock machinery in mice. Inhibition of NAMPT promotes oscillation of the clock gene Per2 by releasing CLOCK:BMAL1 from suppression by SIRT1. In turn, the circadian transcription factor CLOCK binds to and up-regulates Nampt, thus completing a feedback loop involving NAMPT/NAD+ and SIRT1/CLOCK:BMAL1.

  19. Revealing a circadian clock in captive arctic-breeding songbirds, lapland longspurs (Calcarius lapponicus), under constant illumination.

    Science.gov (United States)

    Ashley, Noah T; Ubuka, Takayoshi; Schwabl, Ingrid; Goymann, Wolfgang; Salli, Brady M; Bentley, George E; Buck, C Loren

    2014-12-01

    Most organisms in temperate or tropic regions employ the light-dark (LD) cycle as the primary Zeitgeber to synchronize circadian rhythms. At higher latitudes (>66°33'), continuous illumination during the summer presents a significant time-keeping dilemma for polar-adapted species. Lapland longspurs (Calcarius lapponicus), arctic-breeding migratory songbirds, are one of the few recorded species maintaining an intact diel rhythm in activity and plasma melatonin titers during polar summer. However, it is unknown whether rhythms are endogenous and entrain to low-amplitude polar Zeitgeber signals, such as daily variations in light intensity and the spectral composition of the sun (as measured by color temperature). Wild-caught male and female longspurs were brought into captivity, and locomotor activity was assessed using infrared detection. To examine if rhythms were endogenous, birds were exposed to constant bright light (LL; 1300 lux) or constant darkness (DD; 0.1 lux). All birds exhibited free-running activity rhythms in LL and DD, suggesting the presence of a functional circadian clock. Mean periods in LL (22.86 h) were significantly shorter than those in DD (23.5 h), in accordance with Aschoff's rule. No birds entrained to diel changes in light intensity, color temperature, or both. To examine endogenous molecular clock function, the Per2 gene was partially cloned in longspurs (llPer2) and transcripts were measured in hypothalamic tissue punches, eye, and liver using competitive polymerase chain reaction. Ocular llPer2 gene expression was periodic in LL and elevated at ZT24 (CT24) for LD or constant conditions (LL and DD), but llPer2 rhythmicity was not detected in hypothalamus or liver. Plasma melatonin was significantly lower in LL compared with LD or DD. In conclusion, rhythmic ocular Per2 expression and melatonin secretion may maintain the circadian activity rhythm across the polar day.

  20. Natural selection against a circadian clock gene mutation in mice

    NARCIS (Netherlands)

    Spoelstra, K.; Wikelski, Martin; Daan, Serge; Loudon, Andrew; Hau, Michaela

    2016-01-01

    Circadian rhythms with an endogenous period close or equal to the natural light-dark cycle are considered evolutionarily adaptive (‘circadian resonance hypothesis’). Despite remarkable insight into the molecular mechanisms driving circadian cycles, this hypothesis has not been tested under natural c

  1. Natural selection against a circadian clock gene mutation in mice

    NARCIS (Netherlands)

    Spoelstra, Kamiel; Wikelski, Martin; Daan, Serge; Loudon, Andrew S I; Hau, Michaela

    2016-01-01

    Circadian rhythms with an endogenous period close to or equal to the natural light-dark cycle are considered evolutionarily adaptive ("circadian resonance hypothesis"). Despite remarkable insight into the molecular mechanisms driving circadian cycles, this hypothesis has not been tested under natura

  2. A circadian clock in Saccharomyces cerevisiae

    NARCIS (Netherlands)

    Eelderink-Chen, Zheng; Mazzotta, Gabriella; Sturre, Marcel; Bosman, Jasper; Roenneberg, Till; Merrow, Martha

    2010-01-01

    Circadian timing is a fundamental biological process, underlying cellular physiology in animals, plants, fungi, and cyanobacteria. Circadian clocks organize gene expression, metabolism, and behavior such that they occur at specific times of day. The biological clocks that orchestrate these daily cha

  3. Using circadian entrainment to find cryptic clocks

    NARCIS (Netherlands)

    Eelderink-Chen, Zheng; Olmedo, Maria; Bosman, Jasper; Merrow, Martha

    2015-01-01

    Three properties are most often attributed to the circadian clock: a ca. 24-h free-running rhythm, temperature compensation of the circadian rhythm, and its entrainment to zeitgeber cycles. Relatively few experiments, however, are performed under entrainment conditions. Rather, most chronobiology pr

  4. Improving machinery reliability

    CERN Document Server

    Bloch, Heinz P

    1998-01-01

    This totally revised, updated and expanded edition provides proven techniques and procedures that extend machinery life, reduce maintenance costs, and achieve optimum machinery reliability. This essential text clearly describes the reliability improvement and failure avoidance steps practiced by best-of-class process plants in the U.S. and Europe.

  5. Cross-talk between the circadian clock and the cell cycle in cancer.

    Science.gov (United States)

    Soták, Matúš; Sumová, Alena; Pácha, Jiří

    2014-06-01

    The circadian clock is an endogenous timekeeper system that controls the daily rhythms of a variety of physiological processes. Accumulating evidence indicates that genetic changes or unhealthy lifestyle can lead to a disruption of circadian homeostasis, which is a risk factor for severe dysfunctions and pathologies including cancer. Cell cycle, proliferation, and cell death are closely intertwined with the circadian clock, and thus disruption of circadian rhythms appears to be linked to cancer development and progression. At the molecular level, the cell cycle machinery and the circadian clocks are controlled by similar mechanisms, including feedback loops of genes and protein products that display periodic activation and repression. Here, we review the circadian rhythmicity of genes associated with the cell cycle, proliferation, and apoptosis, and we highlight the potential connection between these processes, the circadian clock, and neoplastic transformations. Understanding these interconnections might have potential implications for the prevention and therapy of malignant diseases.

  6. The circadian clock coordinates ribosome biogenesis.

    Directory of Open Access Journals (Sweden)

    Céline Jouffe

    Full Text Available Biological rhythms play a fundamental role in the physiology and behavior of most living organisms. Rhythmic circadian expression of clock-controlled genes is orchestrated by a molecular clock that relies on interconnected negative feedback loops of transcription regulators. Here we show that the circadian clock exerts its function also through the regulation of mRNA translation. Namely, the circadian clock influences the temporal translation of a subset of mRNAs involved in ribosome biogenesis by controlling the transcription of translation initiation factors as well as the clock-dependent rhythmic activation of signaling pathways involved in their regulation. Moreover, the circadian oscillator directly regulates the transcription of ribosomal protein mRNAs and ribosomal RNAs. Thus the circadian clock exerts a major role in coordinating transcription and translation steps underlying ribosome biogenesis.

  7. Network news: prime time for systems biology of the plant circadian clock truncated form of the title: Plant circadian clocks

    Science.gov (United States)

    McClung, C. Robertson; Gutiérrez, Rodrigo A.

    2011-01-01

    Summary Whole-transcriptome analyses have established that the plant circadian clock regulates virtually every plant biological process and most prominently hormonal and stress response pathways. Systems biology efforts have successfully modeled the plant central clock machinery and an iterative process of model refinement and experimental validation has contributed significantly to the current view of the central clock machinery. The challenge now is to connect this central clock to the output pathways for understanding how the plant circadian clock contributes to plant growth and fitness in a changing environment. Undoubtedly, systems approaches will be needed to integrate and model the vastly increased volume of experimental data in order to extract meaningful biological information. Thus, we have entered an era of systems modeling, experimental testing, and refinement. This approach, coupled with advances from the genetic and biochemical analyses of clock function, is accelerating our progress towards a comprehensive understanding of the plant circadian clock network. PMID:20889330

  8. Circadian Systems and Metabolism

    NARCIS (Netherlands)

    Roenneberg, Till; Merrow, Martha

    1999-01-01

    Circadian systems direct many metabolic parameters and, at the same time, they appear to be exquisitely shielded from metabolic variations. Although the recent decade of circadian research has brought insights into how circadian periodicity may be generated at the molecular level, little is known ab

  9. The circadian clock and cell cycle: interconnected biological circuits.

    Science.gov (United States)

    Masri, Selma; Cervantes, Marlene; Sassone-Corsi, Paolo

    2013-12-01

    The circadian clock governs biological timekeeping on a systemic level, helping to regulate and maintain physiological processes, including endocrine and metabolic pathways with a periodicity of 24-hours. Disruption within the circadian clock machinery has been linked to numerous pathological conditions, including cancer, suggesting that clock-dependent regulation of the cell cycle is an essential control mechanism. This review will highlight recent advances on the 'gating' controls of the circadian clock at various checkpoints of the cell cycle and also how the cell cycle can influence biological rhythms. The reciprocal influence that the circadian clock and cell cycle exert on each other suggests that these intertwined biological circuits are essential and multiple regulatory/control steps have been instated to ensure proper timekeeping.

  10. Coordination of the maize transcriptome by a conserved circadian clock

    Directory of Open Access Journals (Sweden)

    Harmon Frank G

    2010-06-01

    Full Text Available Abstract Background The plant circadian clock orchestrates 24-hour rhythms in internal physiological processes to coordinate these activities with daily and seasonal changes in the environment. The circadian clock has a profound impact on many aspects of plant growth and development, including biomass accumulation and flowering time. Despite recent advances in understanding the circadian system of the model plant Arabidopsis thaliana, the contribution of the circadian oscillator to important agronomic traits in Zea mays and other cereals remains poorly defined. To address this deficit, this study investigated the transcriptional landscape of the maize circadian system. Results Since transcriptional regulation is a fundamental aspect of circadian systems, genes exhibiting circadian expression were identified in the sequenced maize inbred B73. Of the over 13,000 transcripts examined, approximately 10 percent displayed circadian expression patterns. The majority of cycling genes had peak expression at subjective dawn and dusk, similar to other plant circadian systems. The maize circadian clock organized co-regulation of genes participating in fundamental physiological processes, including photosynthesis, carbohydrate metabolism, cell wall biogenesis, and phytohormone biosynthesis pathways. Conclusions Circadian regulation of the maize genome was widespread and key genes in several major metabolic pathways had circadian expression waveforms. The maize circadian clock coordinated transcription to be coincident with oncoming day or night, which was consistent with the circadian oscillator acting to prepare the plant for these major recurring environmental changes. These findings highlighted the multiple processes in maize plants under circadian regulation and, as a result, provided insight into the important contribution this regulatory system makes to agronomic traits in maize and potentially other C4 plant species.

  11. Cavitation in Hydraulic Machinery

    Energy Technology Data Exchange (ETDEWEB)

    Kjeldsen, M.

    1996-11-01

    The main purpose of this doctoral thesis on cavitation in hydraulic machinery is to change focus towards the coupling of non-stationary flow phenomena and cavitation. It is argued that, in addition to turbulence, superimposed sound pressure fluctuations can have a major impact on cavitation and lead to particularly severe erosion. For the design of hydraulic devices this finding may indicate how to further limit the cavitation problems. Chapter 1 reviews cavitation in general in the context of hydraulic machinery, emphasizing the initial cavitation event and the role of the water quality. Chapter 2 discusses the existence of pressure fluctuations for situations common in such machinery. Chapter 3 on cavitation dynamics presents an algorithm for calculating the nucleation of a cavity cluster. Chapter 4 describes the equipment used in this work. 53 refs., 55 figs.,10 tabs.

  12. Circadian Rhythms, Sleep Deprivation, and Human Performance

    Science.gov (United States)

    Goel, Namni; Basner, Mathias; Rao, Hengyi; Dinges, David F.

    2014-01-01

    Much of the current science on, and mathematical modeling of, dynamic changes in human performance within and between days is dominated by the two-process model of sleep–wake regulation, which posits a neurobiological drive for sleep that varies homeostatically (increasing as a saturating exponential during wakefulness and decreasing in a like manner during sleep), and a circadian process that neurobiologically modulates both the homeostatic drive for sleep and waking alertness and performance. Endogenous circadian rhythms in neurobehavioral functions, including physiological alertness and cognitive performance, have been demonstrated using special laboratory protocols that reveal the interaction of the biological clock with the sleep homeostatic drive. Individual differences in circadian rhythms and genetic and other components underlying such differences also influence waking neurobehavioral functions. Both acute total sleep deprivation and chronic sleep restriction increase homeostatic sleep drive and degrade waking neurobehavioral functions as reflected in sleepiness, attention, cognitive speed, and memory. Recent evidence indicating a high degree of stability in neurobehavioral responses to sleep loss suggests that these trait-like individual differences are phenotypic and likely involve genetic components, including circadian genes. Recent experiments have revealed both sleep homeostatic and circadian effects on brain metabolism and neural activation. Investigation of the neural and genetic mechanisms underlying the dynamically complex interaction between sleep homeostasis and circadian systems is beginning. A key goal of this work is to identify biomarkers that accurately predict human performance in situations in which the circadian and sleep homeostatic systems are perturbed. PMID:23899598

  13. Multisensor Fused Fault Diagnosis for Rotation Machinery Based on Supervised Second-Order Tensor Locality Preserving Projection and Weighted k-Nearest Neighbor Classifier under Assembled Matrix Distance Metric

    Directory of Open Access Journals (Sweden)

    Fen Wei

    2016-01-01

    Full Text Available In order to sufficiently capture the useful fault-related information available in the multiple vibration sensors used in rotation machinery, while concurrently avoiding the introduction of the limitation of dimensionality, a new fault diagnosis method for rotation machinery based on supervised second-order tensor locality preserving projection (SSTLPP and weighted k-nearest neighbor classifier (WKNNC with an assembled matrix distance metric (AMDM is presented. Second-order tensor representation of multisensor fused conditional features is employed to replace the prevailing vector description of features from a single sensor. Then, an SSTLPP algorithm under AMDM (SSTLPP-AMDM is presented to realize dimensional reduction of original high-dimensional feature tensor. Compared with classical second-order tensor locality preserving projection (STLPP, the SSTLPP-AMDM algorithm not only considers both local neighbor information and class label information but also replaces the existing Frobenius distance measure with AMDM for construction of the similarity weighting matrix. Finally, the obtained low-dimensional feature tensor is input into WKNNC with AMDM to implement the fault diagnosis of the rotation machinery. A fault diagnosis experiment is performed for a gearbox which demonstrates that the second-order tensor formed multisensor fused fault data has good results for multisensor fusion fault diagnosis and the formulated fault diagnosis method can effectively improve diagnostic accuracy.

  14. Bacterial mitotic machineries

    DEFF Research Database (Denmark)

    Gerdes, Kenn; Møller-Jensen, Jakob; Ebersbach, Gitte

    2004-01-01

    Here, we review recent progress that yields fundamental new insight into the molecular mechanisms behind plasmid and chromosome segregation in prokaryotic cells. In particular, we describe how prokaryotic actin homologs form mitotic machineries that segregate DNA before cell division. Thus, the P...

  15. Circadian clock circuitry in colorectal cancer.

    Science.gov (United States)

    Mazzoccoli, Gianluigi; Vinciguerra, Manlio; Papa, Gennaro; Piepoli, Ada

    2014-04-21

    Colorectal cancer is the most prevalent among digestive system cancers. Carcinogenesis relies on disrupted control of cellular processes, such as metabolism, proliferation, DNA damage recognition and repair, and apoptosis. Cell, tissue, organ and body physiology is characterized by periodic fluctuations driven by biological clocks operating through the clock gene machinery. Dysfunction of molecular clockworks and cellular oscillators is involved in tumorigenesis, and altered expression of clock genes has been found in cancer patients. Epidemiological studies have shown that circadian disruption, that is, alteration of bodily temporal organization, is a cancer risk factor, and an increased incidence of colorectal neoplastic disease is reported in shift workers. In this review we describe the involvement of the circadian clock circuitry in colorectal carcinogenesis and the therapeutic strategies addressing temporal deregulation in colorectal cancer.

  16. Circadian Rhythms, Sleep, and Disorders of Aging.

    Science.gov (United States)

    Mattis, Joanna; Sehgal, Amita

    2016-04-01

    Sleep-wake cycles are known to be disrupted in people with neurodegenerative disorders. These findings are now supported by data from animal models for some of these disorders, raising the question of whether the disrupted sleep/circadian regulation contributes to the loss of neural function. As circadian rhythms and sleep consolidation also break down with normal aging, changes in these may be part of what makes aging a risk factor for disorders like Alzheimer's disease (AD). Mechanisms underlying the connection between circadian/sleep dysregulation and neurodegeneration remain unclear, but several recent studies provide interesting possibilities. While mechanistic analysis is under way, it is worth considering treatment of circadian/sleep disruption as a means to alleviate symptoms of neurodegenerative disorders.

  17. Exploitation of host clock gene machinery by hepatitis viruses B and C.

    Science.gov (United States)

    Vinciguerra, Manlio; Mazzoccoli, Gianluigi; Piccoli, Claudia; Tataranni, Tiziana; Andriulli, Angelo; Pazienza, Valerio

    2013-12-21

    Many aspects of cellular physiology display circadian (approximately 24-h) rhythms. Dysfunction of the circadian clock molecular circuitry is associated with human health derangements, including neurodegeneration, increased risk of cancer, cardiovascular diseases and the metabolic syndrome. Viruses triggering hepatitis depend tightly on the host cell synthesis machinery for their own replication, survival and spreading. Recent evidences support a link between the circadian clock circuitry and viruses' biological cycle within host cells. Currently, in vitro models for chronobiological studies of cells infected with viruses need to be implemented. The establishment of such in vitro models would be helpful to better understand the link between the clock gene machinery and viral replication/viral persistence in order to develop specifically targeted therapeutic regimens. Here we review the recent literature dealing with the interplay between hepatitis B and C viruses and clock genes.

  18. Circadian rhythms of women with fibromyalgia

    Science.gov (United States)

    Klerman, E. B.; Goldenberg, D. L.; Brown, E. N.; Maliszewski, A. M.; Adler, G. K.

    2001-01-01

    Fibromyalgia syndrome is a chronic and debilitating disorder characterized by widespread nonarticular musculoskeletal pain whose etiology is unknown. Many of the symptoms of this syndrome, including difficulty sleeping, fatigue, malaise, myalgias, gastrointestinal complaints, and decreased cognitive function, are similar to those observed in individuals whose circadian pacemaker is abnormally aligned with their sleep-wake schedule or with local environmental time. Abnormalities in melatonin and cortisol, two hormones whose secretion is strongly influenced by the circadian pacemaker, have been reported in women with fibromyalgia. We studied the circadian rhythms of 10 women with fibromyalgia and 12 control healthy women. The protocol controlled factors known to affect markers of the circadian system, including light levels, posture, sleep-wake state, meals, and activity. The timing of the events in the protocol were calculated relative to the habitual sleep-wake schedule of each individual subject. Under these conditions, we found no significant difference between the women with fibromyalgia and control women in the circadian amplitude or phase of rhythms of melatonin, cortisol, and core body temperature. The average circadian phases expressed in hours posthabitual bedtime for women with and without fibromyalgia were 3:43 +/- 0:19 and 3:46 +/- 0:13, respectively, for melatonin; 10:13 +/- 0:23 and 10:32 +/- 0:20, respectively for cortisol; and 5:19 +/- 0:19 and 4:57 +/- 0:33, respectively, for core body temperature phases. Both groups of women had similar circadian rhythms in self-reported alertness. Although pain and stiffness were significantly increased in women with fibromyalgia compared with healthy women, there were no circadian rhythms in either parameter. We suggest that abnormalities in circadian rhythmicity are not a primary cause of fibromyalgia or its symptoms.

  19. Circadian modulation of interval timing in mice.

    Science.gov (United States)

    Agostino, Patricia V; do Nascimento, Micaela; Bussi, Ivana L; Eguía, Manuel C; Golombek, Diego A

    2011-01-25

    Temporal perception is fundamental to environmental adaptation in humans and other animals. To deal with timing and time perception, organisms have developed multiple systems that are active over a broad range of order of magnitude, the most important being circadian timing, interval timing and millisecond timing. The circadian pacemaker is located in the suprachiasmatic nuclei (SCN) of the hypothalamus, and is driven by a self-sustaining oscillator with a period close to 24h. Time estimation in the second-to-minutes range--known as interval timing--involves the interaction of the basal ganglia and the prefrontal cortex. In this work we tested the hypothesis that interval timing in mice is sensitive to circadian modulations. Animals were trained following the peak-interval (PI) procedure. Results show significant differences in the estimation of 24-second intervals at different times of day, with a higher accuracy in the group trained at night, which were maintained under constant dark (DD) conditions. Interval timing was also studied in animals under constant light (LL) conditions, which abolish circadian rhythmicity. Mice under LL conditions were unable to acquire temporal control in the peak interval procedure. Moreover, short time estimation in animals subjected to circadian desynchronizations (modeling jet lag-like situations) was also affected. Taken together, our results indicate that short-time estimation is modulated by the circadian clock. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. The Resource Benefits Evaluation Model on Remanufacturing Processes of End-of-Life Construction Machinery under the Uncertainty in Recycling Price

    Directory of Open Access Journals (Sweden)

    Qian-wang Deng

    2017-02-01

    Full Text Available In the process of end-of-life construction machinery remanufacturing, the existence of uncertainties in all aspects of the remanufacturing process increase the difficulty and complexity of resource benefits evaluation for them. To quantify the effects of those uncertainty factors, this paper makes a mathematical analysis of the recycling and remanufacturing processes, building a resource benefits evaluation model for the end-of-life construction machinery. The recycling price and the profits of remanufacturers can thereby be obtained with a maximum remanufacturing resource benefit. The study investigates the change regularity of the resource benefits, recycling price, and profits of remanufacturers when the recycling price, quality fluctuation coefficient, demand coefficient, and the reusing ratio of products or parts are varying. In the numerical experiment, we explore the effects of uncertainties on the remanufacturing decisions and the total expected costs. The simulated analysis shows when the quality fluctuation coefficient is approaching to 1, the values of the profits of remanufacturer, the maximal resource benefits and recycling price grade into constants.

  1. Vibration of hydraulic machinery

    CERN Document Server

    Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong

    2013-01-01

    Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...

  2. Heritable circadian period length in a wild bird population

    NARCIS (Netherlands)

    Helm, Barbara; Visser, Marcel E.

    2010-01-01

    Timing is essential, but circadian clocks, which play a crucial role in timekeeping, are almost unaddressed in evolutionary ecology. A key property of circadian clocks is their free-running period length (tau), i.e. the time taken for a full cycle under constant conditions. Under laboratory conditio

  3. PDFR and CRY signaling converge in a subset of clock neurons to modulate the amplitude and phase of circadian behavior in Drosophila.

    Directory of Open Access Journals (Sweden)

    Seol Hee Im

    Full Text Available BACKGROUND: To synchronize their molecular rhythms, circadian pacemaker neurons must input both external and internal timing cues and, therefore, signal integration between sensory information and internal clock status is fundamental to normal circadian physiology. METHODOLOGY/PRINCIPAL FINDINGS: We demonstrate the specific convergence of clock-derived neuropeptide signaling with that of a deep brain photoreceptor. We report that the neuropeptide PDF receptor and the circadian photoreceptor CRYPTOCROME (CRY are precisely co-expressed in a subset of pacemakers, and that these pathways together provide a requisite drive for circadian control of daily locomotor rhythms. These convergent signaling pathways influence the phase of rhythm generation, but also its amplitude. In the absence of both pathways, PER rhythms were greatly reduced in only those specific pacemakers that receive convergent inputs and PER levels remained high in the nucleus throughout the day. This suggested a large-scale dis-regulation of the pacemaking machinery. Behavioral rhythms were likewise disrupted: in light:dark conditions they were aberrant, and under constant dark conditions, they were lost. CONCLUSIONS/SIGNIFICANCE: We speculate that the convergence of environmental and clock-derived signals may produce a coincident detection of light, synergistic responses to it, and thus more accurate and more efficient re-setting properties.

  4. The RNA polymerase I transcription machinery.

    Science.gov (United States)

    Russell, Jackie; Zomerdijk, Joost C B M

    2006-01-01

    The rRNAs constitute the catalytic and structural components of the ribosome, the protein synthesis machinery of cells. The level of rRNA synthesis, mediated by Pol I (RNA polymerase I), therefore has a major impact on the life and destiny of a cell. In order to elucidate how cells achieve the stringent control of Pol I transcription, matching the supply of rRNA to demand under different cellular growth conditions, it is essential to understand the components and mechanics of the Pol I transcription machinery. In this review, we discuss: (i) the molecular composition and functions of the Pol I enzyme complex and the two main Pol I transcription factors, SL1 (selectivity factor 1) and UBF (upstream binding factor); (ii) the interplay between these factors during pre-initiation complex formation at the rDNA promoter in mammalian cells; and (iii) the cellular control of the Pol I transcription machinery.

  5. Circadian physiology of metabolism.

    Science.gov (United States)

    Panda, Satchidananda

    2016-11-25

    A majority of mammalian genes exhibit daily fluctuations in expression levels, making circadian expression rhythms the largest known regulatory network in normal physiology. Cell-autonomous circadian clocks interact with daily light-dark and feeding-fasting cycles to generate approximately 24-hour oscillations in the function of thousands of genes. Circadian expression of secreted molecules and signaling components transmits timing information between cells and tissues. Such intra- and intercellular daily rhythms optimize physiology both by managing energy use and by temporally segregating incompatible processes. Experimental animal models and epidemiological data indicate that chronic circadian rhythm disruption increases the risk of metabolic diseases. Conversely, time-restricted feeding, which imposes daily cycles of feeding and fasting without caloric reduction, sustains robust diurnal rhythms and can alleviate metabolic diseases. These findings highlight an integrative role of circadian rhythms in physiology and offer a new perspective for treating chronic diseases in which metabolic disruption is a hallmark.

  6. Circadian Rhythm Sleep Disorders

    Directory of Open Access Journals (Sweden)

    Erhan Akinci

    2016-06-01

    Full Text Available The circadian rhythm sleep disorders define the clinical conditions where sleep and ndash;wake rhythm is disrupted despite optimum environmental and social conditions. They occur as a result of the changes in endogenous circadian hours or non-compatibility of environmental factors or social life with endogenous circadian rhythm. The sleep and ndash;wake rhythm is disrupted continuously or in repeating phases depending on lack of balance between internal and external cycles. This condition leads to functional impairments which cause insomnia, excessive sleepiness or both in people. Application of detailed sleep anamnesis and sleep diary with actigraphy record, if possible, will be sufficient for diagnosis. The treatment aims to align endogenous circadian rhythm with environmental conditions. The purpose of this article is to review pathology, clinical characteristics, diagnosis and treatment of circadian rhythm disorder. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2016; 8(2: 178-189

  7. Bacterial mitotic machineries

    DEFF Research Database (Denmark)

    Gerdes, Kenn; Møller-Jensen, Jakob; Ebersbach, Gitte;

    2004-01-01

    Here, we review recent progress that yields fundamental new insight into the molecular mechanisms behind plasmid and chromosome segregation in prokaryotic cells. In particular, we describe how prokaryotic actin homologs form mitotic machineries that segregate DNA before cell division. Thus, the Par......M protein of plasmid R1 forms F actin-like filaments that separate and move plasmid DNA from mid-cell to the cell poles. Evidence from three different laboratories indicate that the morphogenetic MreB protein may be involved in segregation of the bacterial chromosome....

  8. Chronobiology of micturition: putative role of the circadian clock.

    OpenAIRE

    Negoro, Hiromitsu; Kanematsu, Akihiro; Yoshimura, Koji; Ogawa, Osamu

    2013-01-01

    [Purpose]Mammals urinate less frequently during the sleep period than the awake period. This is modulated by a triad of factors, including decreased arousal in the brain, a decreased urine production rate in the kidneys and increased functional bladder capacity during sleep. The circadian clock is genetic transcription-translation feedback machinery. It exists in most organs and cells, termed the peripheral clock, which is orchestrated by the central clock in the suprachiasmatic nucleus of th...

  9. Development of the circadian clockwork in the kidney

    DEFF Research Database (Denmark)

    Mészáros, Krisztina; Pruess, Linda; Szabó, Attila J.

    2014-01-01

    The circadian molecular clock is an internal time-keeping system composed of centrally synchronized tissue-level pacemakers. Here, we explored the ontogeny of the clock machinery in the developing kidney. Pregnant rats were housed at 12-12 h light-dark cycles. Offsprings were killed at 4-h...... was modified postpartum. Clock, Rev-erbα, Per2, αENaC, SGK1, NHE3, and AVPR2 showed circadian expression at the end of intrauterine development. By 1 week, all genes oscillated with a distinct acrophase shift toward the time of peak feeding activity. Daily 4-hour withdrawal of mothers induced a 12-hour phase...... shift of Clock and Bmal1 expression, while disrupting oscillations of the other genes. After weaning, oscillation phases shifted back toward the adult pattern, which was fully expressed at 12 weeks. Thus, functional circadian molecular clockwork evolves in the late fetal and early postnatal kidney...

  10. The transcription factor Runx2 is under circadian control in the suprachiasmatic nucleus and functions in the control of rhythmic behavior.

    Directory of Open Access Journals (Sweden)

    Meghan E Reale

    Full Text Available Runx2, a member of the family of runt-related transcription factors, is rhythmically expressed in bone and may be involved in circadian rhythms in bone homeostasis and osteogenesis. Runx2 is also expressed in the brain, but its function is unknown. We tested the hypothesis that in the brain, Runx2 may interact with clock-controlled genes to regulate circadian rhythms in behavior. First, we demonstrated diurnal and circadian rhythms in the expression of Runx2 in the mouse brain. Expression of Runx2 mRNA and protein mirrored that of the core clock genes, Period1 and Period2, in the suprachiasmatic nucleus (SCN, the paraventricular nucleus and the olfactory bulb. The rhythm of Runx2 expression was eliminated in the SCN of Bmal1(-/- mice. Moreover, by crossbreeding mPer2(Luc mice with Runx2(+/- mice and recording bioluminescence rhythms, a significant lengthening of the period of rhythms was detected in cultured SCN of Runx2(-/- animals compared to either Runx2(+/- or Runx2(+/+ mice. Behavioral analyses of Runx2 mutant mice revealed that Runx2(+/- animals displayed a significantly lengthened free-running period of running wheel activity compared to Runx2(+/+ littermates. Taken together, these findings provide evidence for clock gene-mediated rhythmic expression of Runx2, and its functional role in regulating circadian period at the level of the SCN and behavior.

  11. Circadian clocks and breast cancer

    OpenAIRE

    Blakeman, Victoria; Jack L. Williams; Meng, Qing-Jun; Streuli, Charles H

    2016-01-01

    Circadian clocks respond to environmental time cues to coordinate 24-hour oscillations in almost every tissue of the body. In the breast, circadian clocks regulate the rhythmic expression of numerous genes. Disrupted expression of circadian genes can alter breast biology and may promote cancer. Here we overview circadian mechanisms, and the connection between the molecular clock and breast biology. We describe how disruption of circadian genes contributes to cancer via multiple mechanisms, an...

  12. Robustness of synthetic circadian clocks to multiple environmental changes.

    Science.gov (United States)

    Gurevich, Lilia; Cohen-Luria, Rivka; Wagner, Nathaniel; Ashkenasy, Gonen

    2015-04-04

    A molecular network that mimics circadian clocks from cyanobacteria is constructed in silico. Simulating its oscillatory behaviour under variable conditions reveals its robustness relative to networks of alternative topologies. The principles for synthetic chemical circadian networks to work properly are consequently highlighted.

  13. Matrix analysis of electrical machinery

    CERN Document Server

    Hancock, N N

    2013-01-01

    Matrix Analysis of Electrical Machinery, Second Edition is a 14-chapter edition that covers the systematic analysis of electrical machinery performance. This edition discusses the principles of various mathematical operations and their application to electrical machinery performance calculations. The introductory chapters deal with the matrix representation of algebraic equations and their application to static electrical networks. The following chapters describe the fundamentals of different transformers and rotating machines and present torque analysis in terms of the currents based on the p

  14. [Circadian regulation of sleep-wake cycles and food anticipation].

    Science.gov (United States)

    Nakamura, Wataru

    2012-06-01

    The circadian clock is crucial for efficient physiological function and drives the temporal regulation of the sleep-wake state, metabolism, and behavior. The timing of food intake and the accompanying behavior are both controlled by the internal clock, which is located in the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. The SCN is considered as the master clock because the circadian rhythms for most physiological and behavioral processes are terminated after SCN ablation. The molecular framework of circadian oscillations can be best studied in the SCN. A "core" set of circadian clock genes form autoregulatory transcription-translation feedback loops that are believed to drive daily rhythms in individual cells. These clock genes are expressed in a circadian manner not only in the SCN but also in other parts of the brain and many peripheral tissues. Mammals can anticipate a predictable daily mealtime through entrainment of circadian oscillators. Because the restriction of food availability to a specific time of the day elicits anticipatory behavior even after ablation of the SCN, such behaviour is assumed to be controlled by another circadian oscillator. In this paper, we have (1) reviewed studies involving the identification of the circadian clock and (2) aimed to elucidate the complex mechanism underlying feeding-associated rhythms by achieving a deep understanding of the circadian phenotypes of the SCN.

  15. Pumping machinery theory and practice

    CERN Document Server

    Badr, Hassan M

    2014-01-01

    Pumping Machinery Theory and Practice comprehensively covers the theoretical foundation and applications of pumping machinery. Key features: Covers characteristics of centrifugal pumps, axial flow pumps and displacement pumpsConsiders pumping machinery performance and operational-type problemsCovers advanced topics in pumping machinery including multiphase flow principles, and two and three-phase flow pumping systemsCovers different methods of flow rate control and relevance to machine efficiency and energy consumptionCovers different methods of flow rate control and relevance to machine effi

  16. Interactions between the circadian clock and metabolism: there are good times and bad times

    Institute of Scientific and Technical Information of China (English)

    Mi Shi; Xiangzhong Zheng

    2013-01-01

    An endogenous circadian (~24 h) clock regulates rhythmic processes of physiology,metabolism and behavior in most living organisms.While able to free-run under constant conditions,the circadian clock is coupled to day:night cycles to increase its amplitude and align the phase of circadian rhythms to the right time of the day.Disruptions of the circadian clock are correlated with brain dysfunctions,cardiovascular diseases and metabolic disorders.In this review,we focus on the interactions between the circadian clock and metabolism.We discuss recent findings on circadian clock regulation of feeding behavior and rhythmic expression of metabolic genes,and present evidence of metabolic input to the circadian clock.We emphasize how misalignment of circadian clocks within the body and with environmental cycles or daily schedules leads to the increasing prevalence of metabolic syndromes in modern society.

  17. Extraordinary behavioral entrainment following circadian rhythm bifurcation in mice.

    Science.gov (United States)

    Harrison, Elizabeth M; Walbeek, Thijs J; Sun, Jonathan; Johnson, Jeremy; Poonawala, Qays; Gorman, Michael R

    2016-12-08

    The mammalian circadian timing system uses light to synchronize endogenously generated rhythms with the environmental day. Entrainment to schedules that deviate significantly from 24 h (T24) has been viewed as unlikely because the circadian pacemaker appears capable only of small, incremental responses to brief light exposures. Challenging this view, we demonstrate that simple manipulations of light alone induce extreme plasticity in the circadian system of mice. Firstly, exposure to dim nocturnal illumination (entrainment. Continuation of dim light is unnecessary for T15/30 behavioral entrainment following bifurcation. Finally, neither dim light alone nor a shortened night is sufficient for the extraordinary entrainment observed under bifurcation. Thus, we demonstrate in a non-pharmacological, non-genetic manipulation that the circadian system is far more flexible than previously thought. These findings challenge the current conception of entrainment and its underlying principles, and reveal new potential targets for circadian interventions.

  18. Circadian modulation of crustacean hyperglycemic hormone in crayfish eyestalk and retina.

    Science.gov (United States)

    Fanjul-Moles, Maria Luisa; Escamilla-Chimal, Elsa Guadalupe; Salceda, Rocio; Giulianini, Piero G; Sánchez-Chávez, Gustavo

    2010-01-01

    Previous studies suggested the retina could be a putative locus of daily crustacean hyperglycemic hormone (CHH) secretion, as it possesses its own metabolic machinery and is independent of the well-known CHH eyestalk locus responsible for the circadian secretion of this peptide. However, it has been proposed that hemolymph glucose and lactate concentrations play a dual role in the regulation of CHH in crayfish. To elucidate the temporal relationship between these two different CHH production loci and to examine their relationship with glucose regulation, we investigated the expression of CHH daily and circadian rhythms in the eyestalk and retina of crayfish using biochemical methods and time series analysis. We wanted to determine whether (1) putative retina and eyestalk CHH rhythmic expressions are correlated and if the oscillations of the two metabolic products of lactate and glucose in the blood due to CHH action on the target tissue correlate, and (2) retina CHH (RCHH) and the possible retinal substrate glycogen and its product glucose are temporally correlated. We found a negative correlation between daily and circadian changes of relative CHH abundance in the retina and eyestalk. This correlation and the cross-correlation values found between eyestalk CHH and hemolymph and glucose confirm that CHH produced by the X-organ sinus gland complex is under the previously proposed dual feedback control system over the 24 h time period. However, the presence of both glycogen and glucose in the retina, the cross-correlation values found between these parameters and hemolymph lactate and glucose, as well as RCHH and hemolymph and retina metabolic markers suggest RCHH is not under the same temporal metabolic control as eyestalk CHH. Nonetheless, their expression may be linked to common rhythms-generating processes.

  19. Postoperative circadian disturbances

    DEFF Research Database (Denmark)

    Gögenur, Ismail

    2010-01-01

    in patients with lower than median pain levels for a three days period after laparoscopic cholecystectomy. In the series of studies included in this thesis we have systematically shown that circadian disturbances are found in the secretion of hormones, the sleep-wake cycle, core body temperature rhythm......An increasing number of studies have shown that circadian variation in the excretion of hormones, the sleep wake circle, the core body temperature rhythm, the tone of the autonomic nervous system and the activity rhythm are important both in health and in disease processes. An increasing attention...... has also been directed towards the circadian variation in endogenous rhythms in relation to surgery. The attention has been directed to the question whether the circadian variation in endogenous rhythms can affect postoperative recovery, morbidity and mortality. Based on the lack of studies where...

  20. Tráfego de máquinas agrícolas e alterações de bioporos em área sob pomar de laranja Agricultural machinery traffic and alterations in biopores under an orange orchard

    Directory of Open Access Journals (Sweden)

    Herdjania Veras de Lima

    2005-10-01

    Full Text Available O estudo micromorfológico permite observar detalhadamente todas as modificações causadas na estrutura e no espaço poroso do solo, impostas pelo cultivo e pelo tráfego de máquinas agrícolas. Este trabalho testou a hipótese de que a compactação causada pelo tráfego de máquinas influi, diferencialmente, na forma e na distribuição das classes de poros, os quais podem ser utilizados como indicadores da qualidade do solo. O objetivo deste trabalho foi avaliar e quantificar, por meio de estudos micromorfológicos, as modificações na porosidade oriunda da atividade biológica (bioporos em um Latossolo Vermelho-Amarelo sob pomar de laranja submetido ao tráfego de máquinas. Amostras indeformadas foram coletadas na superfície (0-12 cm de uma área sob pomar de laranja, abrangendo as posições: entrerodado (ER, rodado (R e projeção da copa (PC, utilizado, como testemunha, um perfil sob mata. Os resultados mostraram que o aumento na diversidade de poros está diretamente relacionado com os processos de degradação da estrutura do solo e que o estudo da ocorrência das classes de poros mostrou-se mais eficiente na identificação da compactação do solo em estádios iniciais que os dados de densidade do solo.Soil micromorphological studies enable a detailed observation of the modifications in soil pore structure and space imposed by cultivation and agricultural machinery traffic. This study tested the hypothesis that compaction caused by machinery affects the form and class distribution of pores in a distinct way and that such alterations can be used as soil quality indicators. The objectives of this study were to evaluate and quantify, through micromorphological studies, the modifications in porosity caused by biological activity (biopores in a Red-Yellow Latosol (Oxisol under an orange orchard subjected to machinery traffic. Undisturbed samples were collected from the surface soil layer (0-12 cm in the following positions: in

  1. Skill Sheets for Agricultural Machinery.

    Science.gov (United States)

    Iowa State Univ. of Science and Technology, Ames. Dept. of Agricultural Education.

    This set of 21 skill sheets for agricultural machinery was developed for use in high school and vocational school agricultural mechanics programs. Each sheet covers a single operational procedure for a piece of agricultural machinery, and includes: (1) a diagram, (2) a step-by-step operational procedure, (3) abilities or understandings taught, (4)…

  2. Circadian rhythms and endocrine functions in adult insects.

    Science.gov (United States)

    Bloch, Guy; Hazan, Esther; Rafaeli, Ada

    2013-01-01

    Many behavioral and physiological processes in adult insects are influenced by both the endocrine and circadian systems, suggesting that these two key physiological systems interact. We reviewed the literature and found that experiments explicitly testing these interactions in adult insects have only been conducted for a few species. There is a shortage of measurements of hormone titers throughout the day under constant conditions even for the juvenile hormones (JHs) and ecdysteroids, the best studied insect hormones. Nevertheless, the available measurements of hormone titers coupled with indirect evidence for circadian modulation of hormone biosynthesis rate, and the expression of genes encoding proteins involved in hormone biosynthesis, binding or degradation are consistent with the hypothesis that the circulating levels of many insect hormones are influenced by the circadian system. Whole genome microarray studies suggest that the modulation of farnesol oxidase levels is important for the circadian regulation of JH biosynthesis in honey bees, mosquitoes, and fruit flies. Several studies have begun to address the functional significance of circadian oscillations in endocrine signaling. The best understood system is the circadian regulation of Pheromone Biosynthesis Activating Neuropeptide (PBAN) titers which is important for the temporal organization of sexual behavior in female moths. The evidence that the circadian and endocrine systems interact has important implications for studies of insect physiology and behavior. Additional studies on diverse species and physiological processes are needed for identifying basic principles underlying the interactions between the circadian and endocrine systems in insects.

  3. 46 CFR 182.465 - Ventilation of spaces containing diesel machinery.

    Science.gov (United States)

    2010-10-01

    ..., with ventilation installations in accordance with ABYC H-32 (incorporated by reference; see 46 CFR 175... 46 Shipping 7 2010-10-01 2010-10-01 false Ventilation of spaces containing diesel machinery. 182... VESSELS (UNDER 100 GROSS TONS) MACHINERY INSTALLATION Specific Machinery Requirements §...

  4. 46 CFR 177.620 - Ventilation of machinery and fuel tank spaces.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Ventilation of machinery and fuel tank spaces. 177.620... (UNDER 100 GROSS TONS) CONSTRUCTION AND ARRANGEMENT Ventilation § 177.620 Ventilation of machinery and... containing machinery or fuel tanks must comply with the requirements of part 182 of this chapter....

  5. Network news: prime time for systems biology of the plant circadian clock.

    Science.gov (United States)

    McClung, C Robertson; Gutiérrez, Rodrigo A

    2010-12-01

    Whole-transcriptome analyses have established that the plant circadian clock regulates virtually every plant biological process and most prominently hormonal and stress response pathways. Systems biology efforts have successfully modeled the plant central clock machinery and an iterative process of model refinement and experimental validation has contributed significantly to the current view of the central clock machinery. The challenge now is to connect this central clock to the output pathways for understanding how the plant circadian clock contributes to plant growth and fitness in a changing environment. Undoubtedly, systems approaches will be needed to integrate and model the vastly increased volume of experimental data in order to extract meaningful biological information. Thus, we have entered an era of systems modeling, experimental testing, and refinement. This approach, coupled with advances from the genetic and biochemical analyses of clock function, is accelerating our progress towards a comprehensive understanding of the plant circadian clock network. Copyright © 2010 Elsevier Ltd. All rights reserved.

  6. Metabolic regulation of circadian clocks.

    Science.gov (United States)

    Haydon, Michael J; Hearn, Timothy J; Bell, Laura J; Hannah, Matthew A; Webb, Alex A R

    2013-05-01

    Circadian clocks are 24-h timekeeping mechanisms, which have evolved in plants, animals, fungi and bacteria to anticipate changes in light and temperature associated with the rotation of the Earth. The current paradigm to explain how biological clocks provide timing information is based on multiple interlocking transcription-translation negative feedback loops (TTFL), which drive rhythmic gene expression and circadian behaviour of growth and physiology. Metabolism is an important circadian output, which in plants includes photosynthesis, starch metabolism, nutrient assimilation and redox homeostasis. There is increasing evidence in a range of organisms that these metabolic outputs can also contribute to circadian timing and might also comprise independent circadian oscillators. In this review, we summarise the mechanisms of circadian regulation of metabolism by TTFL and consider increasing evidence that rhythmic metabolism contributes to the circadian network. We highlight how this might be relevant to plant circadian clock function.

  7. 法制体系背景下的农机安全监理问题探讨%Agricultural machinery safety supervision under the background of legal system

    Institute of Scientific and Technical Information of China (English)

    潘灿松

    2014-01-01

    The article aiming at some problems existing in the work of agricultural machinery safety supervision, a-gricultural machinery safety supervision departments should further strengthen legal nature with agricultural machinery safety supervision system, improve the service quality of the agricultural machinery safety supervision law enforcement team, enhance the promotion of agricultural machinery safety education work.%文章针对目前农机安全监理工作中存在的一些问题,农机安全监理相关部门应进一步加强农机安全监理法制性体系建设,提高农机安全监理执法队伍的业务素质,加强农机安全教育宣传工作。

  8. [Circadian rhythm sleep disorder].

    Science.gov (United States)

    Mishima, Kazuo

    2013-12-01

    Primary pathophysiology of circadian rhythm sleep disorders(CRSDs) is a misalignment between the endogenous circadian rhythm phase and the desired or socially required sleep-wake schedule, or dysfunction of the circadian pacemaker and its afferent/efferent pathways. CRSDs consist of delayed sleep phase type, advanced sleep phase type, free-running type, irregular sleep-wake type, shift work type and jet lag type. Chronotherapy using strong zeitgebers (time cues), such as bright light and melatonin/ melatonin type 2 receptor agonist, is effective when administered with proper timing. Bright light is the strongest entraining agent of circadian rhythms. Bright light therapy (appropriately-timed exposure to bright light) for CRSDs is an effective treatment option, and can shift the sleep-wake cycle to earlier or later times, in order to correct for misalignment between the circadian system and the desired sleep-wake schedule. Timed administration of melatonin, either alone or in combination with light therapy has also been shown to be useful in the treatment of CRSDs.

  9. Circadian rhythm sleep disorders

    Directory of Open Access Journals (Sweden)

    Morgenthaler TI

    2012-05-01

    Full Text Available Bhanu P Kolla,1,2 R Robert Auger,1,2 Timothy I Morgenthaler11Mayo Center for Sleep Medicine, 2Department of Psychiatry and Psychology, Mayo Clinic College of Medicine, Rochester, MN, USAAbstract: Misalignment between endogenous circadian rhythms and the light/dark cycle can result in pathological disturbances in the form of erratic sleep timing (irregular sleep–wake rhythm, complete dissociation from the light/dark cycle (circadian rhythm sleep disorder, free-running type, delayed sleep timing (delayed sleep phase disorder, or advanced sleep timing (advanced sleep phase disorder. Whereas these four conditions are thought to involve predominantly intrinsic mechanisms, circadian dysrhythmias can also be induced by exogenous challenges, such as those imposed by extreme work schedules or rapid transmeridian travel, which overwhelm the ability of the master clock to entrain with commensurate rapidity, and in turn impair approximation to a desired sleep schedule, as evidenced by the shift work and jet lag sleep disorders. This review will focus on etiological underpinnings, clinical assessments, and evidence-based treatment options for circadian rhythm sleep disorders. Topics are subcategorized when applicable, and if sufficient data exist. The length of text associated with each disorder reflects the abundance of associated literature, complexity of management, overlap of methods for assessment and treatment, and the expected prevalence of each condition within general medical practice.Keywords: circadian rhythm sleep disorders, assessment, treatment

  10. Development of the methodology of exhaust emissions measurement under RDE (Real Driving Emissions) conditions for non-road mobile machinery (NRMM) vehicles

    Science.gov (United States)

    Merkisz, J.; Lijewski, P.; Fuc, P.; Siedlecki, M.; Ziolkowski, A.

    2016-09-01

    The paper analyzes the exhaust emissions from farm vehicles based on research performed under field conditions (RDE) according to the NTE procedure. This analysis has shown that it is hard to meet the NTE requirements under field conditions (engine operation in the NTE zone for at least 30 seconds). Due to a very high variability of the engine conditions, the share of a valid number of NTE windows in the field test is small throughout the entire test. For this reason, a modification of the measurement and exhaust emissions calculation methodology has been proposed for farm vehicles of the NRMM group. A test has been developed composed of the following phases: trip to the operation site (paved roads) and field operations (including u-turns and maneuvering). The range of the operation time share in individual test phases has been determined. A change in the method of calculating the real exhaust emissions has also been implemented in relation to the NTE procedure.

  11. [Molecular biology of biological clock--genetic regulation of circadian rhythm and sleep].

    Science.gov (United States)

    Kume, Kazuhiko

    2006-07-01

    Circadian rhythm is a universal biological property functioning in most living species on the earth from bacteria and plants to animals. The molecular mechanisms creating this rhythm have recently been elucidated and the transcriptional feedback loop regulation of 'clock genes' is regarded as essential for all species studied so far. Both mammals and insects share the similar clock genes, which highlights the long conservation of circadian rhythm at the genetic level. Sleep and arousal cycles in mammals are known to be regulated by both homeostatic and circadian processes, but the genetic machinery for sleep regulation is still unclear. Recently, it has been reported that insects also have sleep-like behavior, and we showed that insects use dopamine as a regulator of their sleep/arousal cycling, which strongly suggests the similarity of arousal regulation between insects and mammals at the molecular level. In this review, these recent advancements of the molecular understanding of circadian rhythm and sleep/arousal regulation are outlined.

  12. Postoperative circadian disturbances

    DEFF Research Database (Denmark)

    Gögenur, Ismail

    2010-01-01

    An increasing number of studies have shown that circadian variation in the excretion of hormones, the sleep wake circle, the core body temperature rhythm, the tone of the autonomic nervous system and the activity rhythm are important both in health and in disease processes. An increasing attention...... has also been directed towards the circadian variation in endogenous rhythms in relation to surgery. The attention has been directed to the question whether the circadian variation in endogenous rhythms can affect postoperative recovery, morbidity and mortality. Based on the lack of studies where...... night after minimally invasive surgery. The core body temperature rhythm was disturbed after both major and minor surgery. There was a change in the sleep wake cycle with a significantly increased duration of REM-sleep in the day and evening time after major surgery compared with preoperatively...

  13. Neurospora crassa as a model organism to explore the interconnected network of the cell cycle and the circadian clock.

    Science.gov (United States)

    Zámborszky, Judit; Csikász-Nagy, Attila; Hong, Christian I

    2014-10-01

    Budding and fission yeast pioneered uncovering molecular mechanisms of eukaryotic cell division cycles. However, they do not possess canonical circadian clock machinery that regulates physiological processes with a period of about 24h. On the other hand, Neurospora crassa played a critical role in elucidating molecular mechanisms of circadian rhythms, but have not been utilized frequently for cell cycle studies. Recent findings demonstrate that there exists a conserved coupling between the cell cycle and the circadian clock from N.crassa to Mus musculus, which poses Neurospora as an ideal model organism to investigate molecular mechanisms and emerging behavior of the coupled network of the cell cycle and circadian rhythms. In this review, we briefly describe generic eukaryotic cell cycle regulation focusing on G1/S and G2/M transitions, and highlight that these transitions may be targeted for the circadian clock to influence timing of cell division cycles.

  14. 46 CFR 169.241 - Machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Machinery. 169.241 Section 169.241 Shipping COAST GUARD... Certification Inspections § 169.241 Machinery. (a) At each inspection for certification and periodic inspection.... Mechanisms are operationally tested and visually examined. (3) Auxiliary machinery. All machinery...

  15. Neurobiology of circadian rhythms.

    Science.gov (United States)

    Kumar, V

    1997-09-01

    Adaptation in the temporal environment is key to survival. This is achieved by the manifestation of periodicity in occurrence of vital behavioural and physiological processes at regular intervals--the biological rhythms. Biological rhythms (= biological clocks) are ubiquitous, can be demonstrated persisting at any level of organization in the living world, and are generated and controlled by some central pacemaker(s), mostly located in the brain. In mammals, the suprachiasmatic nucleus (SCN) of the anterior hypothalamus is the principal site of the endogenous circadian pacemaker, regulating many daily physiological and behavioural functions, although other neural structures could also be contributing to the circadian timekeeping system. In other vertebrates, the neural site(s) of the circadian pacemaker is(are) still unclear. An organism without brain can have the biological clock, as well, for fully functional 24-hour temporal organization has been identified in several invertebrates, including unicellular Paramecium and Gonyaulax as well as filamentous fungus, Neurospora. This article attempts to provide an update of the informations which have accumulated over the past decade about understanding of the neurophysiological and molecular bases of circadian rhythms in animals.

  16. CIRCADIAN RHYTMICITY AND DEPRESSION

    Directory of Open Access Journals (Sweden)

    Peter Pregelj

    2008-11-01

    There is a grooving evidence that dysfunction in circadian rhythm regulation andmelatonergic system function is involved in depression pathogenesis. It is known thatclinically used antidepressants have influence on melatonergic system, probably throughchanged ratio between melatonergic type 1 and 2 receptors. With the clinical use of newcompounds like agomelatine that directly regulates melatonergic system new opportunities in depression treatment emerged

  17. Fault tracking of rotating machinery under variable operation based on phase space warping*%变工况下旋转机械故障跟踪的相空间曲变方法*

    Institute of Scientific and Technical Information of China (English)

    范彬; 胡雷; 胡茑庆

    2013-01-01

    For fault prognosis of rotating machinery under variable operation, a fault tracking method based on phase space warping and smooth orthogonal decomposition (SOD) is presented to describe the degradation process of rotating machinery. Firstly, phase space is reconstructed using vibration time-series, and a tracking function of damage evolution is built by quantifying phase space warping. To compensate for cumulative model error and the error caused by variation of local probability distribution of the reference phase space points, the original time-series is partitioned into several data segments and the phase space is partitioned into several subspaces correspondingly. Several feature vectors are concatenated into tracking matrix. Secondly, the different trends caused by actual damage degradation and operation variety in the tracking matrix are separated by smooth orthogonal decomposition. According to smooth orthogonal values, dominant smooth orthogonal coordinates which reflect actual fault degradation trends are extracted. Finally, fault degradation process of bearing out-race is simulated. Rotating speed is varied during the degradation process. Applying the presented method to the degradation process tracking, the tracking matrix is built and decomposed by SOD, and the results show that the proposed method can track the evolution trend of the rotating machinery fault without the influence of operation condition variety.%  为实现在工况变化条件下对旋转机械的故障预测,提出使用相空间曲变和平滑正交分解理论在变工况条件下跟踪旋转机械的故障演化过程。首先在对目标系统的观测时间序列相空间重构的基础上,通过量化相空间曲变构建信号损伤演化的跟踪函数,为弥补累积模型误差和相空间点局部分布概率差异造成的误差,将时间序列和相空间进行分割,并以此构建跟踪矩阵;再利用平滑正交分解方法将跟踪矩阵中分别

  18. Cell "circadian" cycle: new role for mammalian core clock genes.

    Science.gov (United States)

    Borgs, Laurence; Beukelaers, Pierre; Vandenbosch, Renaud; Belachew, Shibeshih; Nguyen, Laurent; Malgrange, Brigitte

    2009-03-15

    In mammals, 24 hours rhythms are organized as a biochemical network of molecular clocks that are operative in all tissues, with the master clock residing in the hypothalamic suprachiasmatic nucleus (SCN). The core pacemakers of these clocks consist of auto-regulatory transcriptional/post-transcriptional feedback loops. Several lines of evidence suggest the existence of a crosstalk between molecules that are responsible for the generation of circadian rhythms and molecules that control the cell cycle progression. In addition, highly specialized cell cycle checkpoints involved in DNA repair after damage seem also, at least in part, mediated by clock proteins. Recent studies have also highlighted a putative connection between clock protein dysfunction and cancer progression. This review discusses the intimate relation that exists between cell cycle progression and components of the circadian machinery.

  19. A circadian rhythm regulating hyphal melanization in Cercospora kikuchii.

    Science.gov (United States)

    Bluhm, Burton H; Burnham, A Michele; Dunkle, Larry D

    2010-01-01

    Many metabolic and developmental processes in fungi are controlled by biological rhythms. Circadian rhythms approximate a daily (24 h) cycle and have been thoroughly studied in the model fungus, Neurospora crassa. However relatively few examples of true circadian rhythms have been documented among other filamentous fungi. In this study we describe a circadian rhythm underlying hyphal melanization in Cercospora kikuchii, an important pathogen of soybean. After growth in light or light : dark cycles, colonies transferred to darkness produced zonate bands of melanized hyphae interspersed with bands of hyaline hyphae. Rhythmic production of bands was remarkably persistent in the absence of external cues, lasting at least 7 d after transfer to darkness, and was compensated over a range of temperatures. As in N. crassa, blue light but not red light was sufficient to entrain the circadian rhythm in C. kikuchii, and a putative ortholog of white collar-1, one of the genes required for light responses in N. crassa, was identified in C. kikuchii. Circadian regulation of melanization is conserved in other members of the genus: Similar rhythms were identified in another field isolate of C. kikuchii as well as field isolates of C. beticola and C. sorghi, but not in wild-type strains of C. zeae-maydis or C. zeina. This report represents the first documented circadian rhythm among Dothideomycete fungi and provides a new opportunity to dissect the molecular basis of circadian rhythms among filamentous fungi.

  20. Photoperiodic plasticity in circadian clock neurons in insects

    Directory of Open Access Journals (Sweden)

    Sakiko eShiga

    2013-08-01

    Full Text Available Since Bünning’s observation of circadian rhythms and photoperiodism in the runner bean Phaseolus multiflorus in 1936, many studies have shown that photoperiodism is based on the circadian clock system. In insects, involvement of circadian clock genes or neurons has been recently shown in the photoperiodic control of developmental arrests, diapause. Based on molecular and neuronal studies in Drosophila melanogaster, photoperiodic changes have been reported for expression patterns of the circadian clock genes, subcellular distribution of clock proteins, fiber distribution, or the number of plausible clock neurons in different species. Photoperiod sets peaks of per or tim mRNA abundance at lights-off in Sarcophaga crassipalpis, Chymomyza costata and Protophormia terraenovae. Abundance of per and Clock mRNA changes by photoperiod in Pyrrhocoris apterus. Subcellular Per distribution in circadian clock neurons changes with photoperiod in P. terraenovae. Although photoperiodism is not known in Leucophaea maderae, under longer day length, more stomata and longer commissural fibers of circadian clock neurons have been found. These plastic changes in the circadian clock neurons could be an important constituent for photoperiodic clock mechanisms to integrate repetitive photoperiodic information and produce different outputs based on day length.

  1. Sleep timing and circadian phase in delayed sleep phase syndrome.

    Science.gov (United States)

    Chang, Anne-Marie; Reid, Kathryn J; Gourineni, Ramadevi; Zee, Phyllis C

    2009-08-01

    Delayed sleep phase syndrome (DSPS) is a circadian rhythm sleep disorder in which the timing of the sleep episode occurs later than desired and is associated with difficulty falling asleep, problems awakening on time (e.g., to meet work or school obligations), and daytime sleepiness. The phase relationship between the timing of sleep and endogenous circadian rhythms is critical to the initiation and maintenance of sleep, and significant alteration leads to impairment of sleep quality and duration. The aim of this retrospective study was to determine the phase relationship between sleep-wake times and physiological markers of circadian timing in clinic patients with DSPS. Objective and subjective measures of sleep timing and circadian phase markers (core body temperature and melatonin) were measured in patients with DSPS and compared with age-matched controls. As expected, significant delays in the timing of the major sleep episode and circadian phase of body temperature and melatonin rhythms were seen in the DSPS group when allowed to sleep at their own habitual schedules, but the phase relationship between sleep-wake times and circadian phase was similar between the 2 groups. These results suggest that the symptoms of insomnia and excessive daytime sleepiness in DSPS patients living under entrained real-life conditions cannot be explained by an alteration in the phase relationship between sleep-wake patterns and other physiological circadian rhythms.

  2. Harmonics of circadian gene transcription in mammals.

    Directory of Open Access Journals (Sweden)

    Michael E Hughes

    2009-04-01

    Full Text Available The circadian clock is a molecular and cellular oscillator found in most mammalian tissues that regulates rhythmic physiology and behavior. Numerous investigations have addressed the contribution of circadian rhythmicity to cellular, organ, and organismal physiology. We recently developed a method to look at transcriptional oscillations with unprecedented precision and accuracy using high-density time sampling. Here, we report a comparison of oscillating transcription from mouse liver, NIH3T3, and U2OS cells. Several surprising observations resulted from this study, including a 100-fold difference in the number of cycling transcripts in autonomous cellular models of the oscillator versus tissues harvested from intact mice. Strikingly, we found two clusters of genes that cycle at the second and third harmonic of circadian rhythmicity in liver, but not cultured cells. Validation experiments show that 12-hour oscillatory transcripts occur in several other peripheral tissues as well including heart, kidney, and lungs. These harmonics are lost ex vivo, as well as under restricted feeding conditions. Taken in sum, these studies illustrate the importance of time sampling with respect to multiple testing, suggest caution in use of autonomous cellular models to study clock output, and demonstrate the existence of harmonics of circadian gene expression in the mouse.

  3. Harmonics of circadian gene transcription in mammals.

    Science.gov (United States)

    Hughes, Michael E; DiTacchio, Luciano; Hayes, Kevin R; Vollmers, Christopher; Pulivarthy, S; Baggs, Julie E; Panda, Satchidananda; Hogenesch, John B

    2009-04-01

    The circadian clock is a molecular and cellular oscillator found in most mammalian tissues that regulates rhythmic physiology and behavior. Numerous investigations have addressed the contribution of circadian rhythmicity to cellular, organ, and organismal physiology. We recently developed a method to look at transcriptional oscillations with unprecedented precision and accuracy using high-density time sampling. Here, we report a comparison of oscillating transcription from mouse liver, NIH3T3, and U2OS cells. Several surprising observations resulted from this study, including a 100-fold difference in the number of cycling transcripts in autonomous cellular models of the oscillator versus tissues harvested from intact mice. Strikingly, we found two clusters of genes that cycle at the second and third harmonic of circadian rhythmicity in liver, but not cultured cells. Validation experiments show that 12-hour oscillatory transcripts occur in several other peripheral tissues as well including heart, kidney, and lungs. These harmonics are lost ex vivo, as well as under restricted feeding conditions. Taken in sum, these studies illustrate the importance of time sampling with respect to multiple testing, suggest caution in use of autonomous cellular models to study clock output, and demonstrate the existence of harmonics of circadian gene expression in the mouse.

  4. Circadian rhythms in insect disease vectors

    Directory of Open Access Journals (Sweden)

    Antonio Carlos Alves Meireles-Filho

    2013-01-01

    Full Text Available Organisms from bacteria to humans have evolved under predictable daily environmental cycles owing to the Earth’s rotation. This strong selection pressure has generated endogenous circadian clocks that regulate many aspects of behaviour, physiology and metabolism, anticipating and synchronising internal time-keeping to changes in the cyclical environment. In haematophagous insect vectors the circadian clock coordinates feeding activity, which is important for the dynamics of pathogen transmission. We have recently witnessed a substantial advance in molecular studies of circadian clocks in insect vector species that has consolidated behavioural data collected over many years, which provided insights into the regulation of the clock in the wild. Next generation sequencing technologies will facilitate the study of vector genomes/transcriptomes both among and within species and illuminate some of the species-specific patterns of adaptive circadian phenotypes that are observed in the field and in the laboratory. In this review we will explore these recent findings and attempt to identify potential areas for further investigation.

  5. Modeling the effects of cell cycle M-phase transcriptional inhibition on circadian oscillation.

    Directory of Open Access Journals (Sweden)

    Bin Kang

    2008-03-01

    Full Text Available Circadian clocks are endogenous time-keeping systems that temporally organize biological processes. Gating of cell cycle events by a circadian clock is a universal observation that is currently considered a mechanism serving to protect DNA from diurnal exposure to ultraviolet radiation or other mutagens. In this study, we put forward another possibility: that such gating helps to insulate the circadian clock from perturbations induced by transcriptional inhibition during the M phase of the cell cycle. We introduced a periodic pulse of transcriptional inhibition into a previously published mammalian circadian model and simulated the behavior of the modified model under both constant darkness and light-dark cycle conditions. The simulation results under constant darkness indicated that periodic transcriptional inhibition could entrain/lock the circadian clock just as a light-dark cycle does. At equilibrium states, a transcriptional inhibition pulse of certain periods was always locked close to certain circadian phases where inhibition on Per and Bmal1 mRNA synthesis was most balanced. In a light-dark cycle condition, inhibitions imposed at different parts of a circadian period induced different degrees of perturbation to the circadian clock. When imposed at the middle- or late-night phase, the transcriptional inhibition cycle induced the least perturbations to the circadian clock. The late-night time window of least perturbation overlapped with the experimentally observed time window, where mitosis is most frequent. This supports our hypothesis that the circadian clock gates the cell cycle M phase to certain circadian phases to minimize perturbations induced by the latter. This study reveals the hidden effects of the cell division cycle on the circadian clock and, together with the current picture of genome stability maintenance by circadian gating of cell cycle, provides a more comprehensive understanding of the phenomenon of circading gating of

  6. Modeling the effects of cell cycle M-phase transcriptional inhibition on circadian oscillation.

    Science.gov (United States)

    Kang, Bin; Li, Yuan-Yuan; Chang, Xiao; Liu, Lei; Li, Yi-Xue

    2008-03-28

    Circadian clocks are endogenous time-keeping systems that temporally organize biological processes. Gating of cell cycle events by a circadian clock is a universal observation that is currently considered a mechanism serving to protect DNA from diurnal exposure to ultraviolet radiation or other mutagens. In this study, we put forward another possibility: that such gating helps to insulate the circadian clock from perturbations induced by transcriptional inhibition during the M phase of the cell cycle. We introduced a periodic pulse of transcriptional inhibition into a previously published mammalian circadian model and simulated the behavior of the modified model under both constant darkness and light-dark cycle conditions. The simulation results under constant darkness indicated that periodic transcriptional inhibition could entrain/lock the circadian clock just as a light-dark cycle does. At equilibrium states, a transcriptional inhibition pulse of certain periods was always locked close to certain circadian phases where inhibition on Per and Bmal1 mRNA synthesis was most balanced. In a light-dark cycle condition, inhibitions imposed at different parts of a circadian period induced different degrees of perturbation to the circadian clock. When imposed at the middle- or late-night phase, the transcriptional inhibition cycle induced the least perturbations to the circadian clock. The late-night time window of least perturbation overlapped with the experimentally observed time window, where mitosis is most frequent. This supports our hypothesis that the circadian clock gates the cell cycle M phase to certain circadian phases to minimize perturbations induced by the latter. This study reveals the hidden effects of the cell division cycle on the circadian clock and, together with the current picture of genome stability maintenance by circadian gating of cell cycle, provides a more comprehensive understanding of the phenomenon of circading gating of cell cycle.

  7. Chronobiology of micturition: putative role of the circadian clock.

    Science.gov (United States)

    Negoro, Hiromitsu; Kanematsu, Akihiro; Yoshimura, Koji; Ogawa, Osamu

    2013-09-01

    Mammals urinate less frequently during the sleep period than the awake period. This is modulated by a triad of factors, including decreased arousal in the brain, a decreased urine production rate in the kidneys and increased functional bladder capacity during sleep. The circadian clock is genetic transcription-translation feedback machinery. It exists in most organs and cells, termed the peripheral clock, which is orchestrated by the central clock in the suprachiasmatic nucleus of the brain. We discuss the linkage between the day and night change in micturition frequency and the genetic rhythm maintained by the circadian clock system, focusing on the brain, kidney and bladder. We performed an inclusive review of the literature on the diurnal change in micturition frequency, urine volume, functional bladder capacity and urodynamics in humans and rodents, relating this to recent basic biological findings about the circadian clock. In humans various behavioral studies demonstrated a diurnal functional change in the kidney and bladder. Conversely, patients with nocturnal enuresis and nocturia showed impairment in this triad of factors. Rats and mice, which are nocturnal animals, also have a micturition frequency rhythm that is decreased during the day, which is the sleep phase for them. Mice with a genetically defective circadian clock system show impaired physiological rhythms in the triad of factors. The existence of the circadian clock has been proven in the brain, kidney and bladder, in which thousands of circadian oscillating genes exist. In the kidney they include genes involved in the regulation of water and major electrolytes. In the bladder they include connexin 43, a gene associated with the regulation of bladder capacity. Recent progress in molecular biology about the circadian clock provides an opportunity to investigate the genetic basis of the micturition rhythm or impairment of the rhythm in nocturnal enuresis and nocturia. If this approach is to be

  8. How pervasive are circadian oscillations?

    OpenAIRE

    2014-01-01

    Circadian oscillations play a critical role in coordinating the physiology, homeostasis, and behavior of biological systems. Once thought to only be controlled by a master clock, recent high-throughput experiments suggest many genes and metabolites in a cell are potentially capable of circadian oscillations. Each cell can reprogram itself and select a relatively small fraction of this broad repertoire for circadian oscillations, as a result of genetic, environmental, and even diet changes.

  9. Textile Machinery: Imports Rebound Again

    Institute of Scientific and Technical Information of China (English)

    Zheng Yan

    2007-01-01

    @@ In the year of 2006, the general situation of China's textile machinery equipment imports had shown a clear sign of revival from the downward trend of two years ago, with a total annual import of 4.1 billion USD, an increase of 19.05% against the same period of 2005.

  10. Tractor & Machinery Safety. 1984 Revision.

    Science.gov (United States)

    Montana State Office of Public Instruction, Helena. Dept. of Vocational Education Services.

    This curriculum guide is intended for use in teaching an instructional unit in tractor and machinery safety that is geared toward college freshmen. Addressed in the individual lessons of the unit are the following topics: understanding the importance of safe and efficient tractor operation, understanding the characteristics of tractors, preparing…

  11. Circadian Regulation of Synaptic Plasticity

    Directory of Open Access Journals (Sweden)

    Marcos G. Frank

    2016-07-01

    Full Text Available Circadian rhythms refer to oscillations in biological processes with a period of approximately 24 h. In addition to the sleep/wake cycle, there are circadian rhythms in metabolism, body temperature, hormone output, organ function and gene expression. There is also evidence of circadian rhythms in synaptic plasticity, in some cases driven by a master central clock and in other cases by peripheral clocks. In this article, I review the evidence for circadian influences on synaptic plasticity. I also discuss ways to disentangle the effects of brain state and rhythms on synaptic plasticity.

  12. The RNA polymerase I transcription machinery

    OpenAIRE

    Russell, Jackie; Zomerdijk, Joost C. B. M.

    2006-01-01

    The rRNAs constitute the catalytic and structural components of the ribosome, the protein synthesis machinery of cells. The level of rRNA synthesis, mediated by Pol I (RNA polymerase I), therefore has a major impact on the life and destiny of a cell. In order to elucidate how cells achieve the stringent control of Pol I transcription, matching the supply of rRNA to demand under different cellular growth conditions, it is essential to understand the components and mechanics of the Pol I transc...

  13. Cross-talk between Circadian clocks, Sleep-wake Cycles and Metabolic Networks: Dispelling the Darkness

    OpenAIRE

    Ray, Sandipan; Reddy, Akhilesh B.

    2016-01-01

    This is the final version of the article. It first appeared from Wiley via https://doi.org/10.1002/bies.201500056 Integration of knowledge concerning circadian rhythms, metabolic networks, and sleep-wake cycles is imperative for unraveling the mysteries of biological cycles and their underlying mechanisms. During the last decade, enormous progress in circadian biology research has provided a plethora of new insights into the molecular architecture of circadian clocks. However, the recent i...

  14. [Melatonin as a regulator of human sleep and circadian systems].

    Science.gov (United States)

    Mishima, Kazuo

    2012-07-01

    Melatonin(N-acetyl-5-methoxytryptamine) is synthesized from tryptophan and is intensively secreted into the blood only in darkness (nighttime) by the pineal gland. Melatonin is not only the most reliable marker of internal circadian phase but also a potent sleep-promoting and circadian phase regulatory agent in humans. There is evidence that daytime administered melatonin is able to exhibit short-acting hypnagogic effect and phase-shifting of the circadian rhythms such that sleep timing and associated various physiological functions realign at a new desired phase. Under favor of these properties, melatonin and melatonin receptor agonists have been shown to be potent therapeutic agents for the treatment of circadian rhythm sleep disorders and some type of insomnia.

  15. Long-Range Chromosome Interactions Mediated by Cohesin Shape Circadian Gene Expression.

    Directory of Open Access Journals (Sweden)

    Yichi Xu

    2016-05-01

    Full Text Available Mammalian circadian rhythm is established by the negative feedback loops consisting of a set of clock genes, which lead to the circadian expression of thousands of downstream genes in vivo. As genome-wide transcription is organized under the high-order chromosome structure, it is largely uncharted how circadian gene expression is influenced by chromosome architecture. We focus on the function of chromatin structure proteins cohesin as well as CTCF (CCCTC-binding factor in circadian rhythm. Using circular chromosome conformation capture sequencing, we systematically examined the interacting loci of a Bmal1-bound super-enhancer upstream of a clock gene Nr1d1 in mouse liver. These interactions are largely stable in the circadian cycle and cohesin binding sites are enriched in the interactome. Global analysis showed that cohesin-CTCF co-binding sites tend to insulate the phases of circadian oscillating genes while cohesin-non-CTCF sites are associated with high circadian rhythmicity of transcription. A model integrating the effects of cohesin and CTCF markedly improved the mechanistic understanding of circadian gene expression. Further experiments in cohesin knockout cells demonstrated that cohesin is required at least in part for driving the circadian gene expression by facilitating the enhancer-promoter looping. This study provided a novel insight into the relationship between circadian transcriptome and the high-order chromosome structure.

  16. 新形势下昌图县农机安全生产监管工作中存在的问题及对策%Existing Problems in the Agricultural Machinery Safety Supervision Work and Countermeasure under the New Situation in Changtu Country

    Institute of Scientific and Technical Information of China (English)

    丁长杰

    2016-01-01

    农机安全生产是农村经济发展的重要因素,也是实现社会稳定和谐的关键。分析新形势下农机监管面临的严峻挑战及存在的问题,有针对性地研究制定一系列切实可行的措施、对策,以达到农机安全生产,促进昌图县农机化事业健康快速发展。%Agricultural machinery safety in production is the important factor of rural economic development, and also is the key of re-alizing social stability and harmonious. This paper analyzed severe challenge facing by agricultural machinery supervision and existing problems under the new situation, and accordingly researched and worked out a series of feasible countermeasures, so as to achieve a-gricultural machinery safety in production and promoting development of agricultural machinery healthy and fast in Changtu country.

  17. Circadian Metabolism in the Light of Evolution

    DEFF Research Database (Denmark)

    Gerhart-Hines, Zachary; Lazar, Mitchell A.

    2015-01-01

    A review. Circadian rhythm, or daily oscillation, of behaviors and biol. processes is a fundamental feature of mammalian physiol. that has developed over hundreds of thousands of years under the continuous evolutionary pressure of energy conservation and efficiency. Evolution has fine...... energetic balance and adaptability, and it discusses potential therapeutic strategies to reset clock metabolic control to modern time for the benefit of human health. [on SciFinder(R)]...

  18. Energy Savings Thanks to French Textile Machinery

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ The French Textile Machinery Manufacturers' Association (UCMTF) has presented, during a seminar it organized for textile professionals and students, the spectacular energy savings achieved thanks to state of the art machinery.

  19. Italian Textile Machinery Seminar in Bangladesh

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The Association of Italian Textile Machinery Manufacturers (ACIMIT) and the Italian Trade Commission will hold a technological seminar on "Italian textile machinery: the way to improve Bangladesh textile competitiveness"

  20. 30 CFR 56.14204 - Machinery lubrication.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Machinery lubrication. 56.14204 Section 56.14204 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Equipment Safety Practices and Operational Procedures § 56.14204 Machinery lubrication. Machinery...

  1. 30 CFR 57.14204 - Machinery lubrication.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Machinery lubrication. 57.14204 Section 57.14204 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL... Equipment Safety Practices and Operational Procedures § 57.14204 Machinery lubrication. Machinery...

  2. 46 CFR 176.804 - Machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Machinery. 176.804 Section 176.804 Shipping COAST GUARD... CERTIFICATION Material Inspections § 176.804 Machinery. At each initial and subsequent inspection for... ready for inspections of machinery, fuel, and piping systems, including the following: (a) Operation...

  3. 46 CFR 130.450 - Machinery alarms.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Machinery alarms. 130.450 Section 130.450 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS VESSEL CONTROL, AND MISCELLANEOUS EQUIPMENT AND SYSTEMS Automation of Unattended Machinery Spaces § 130.450 Machinery alarms....

  4. A Thought on The Training work of Agricultural Machinery Training Work Under the New Normal%新常态下农机校培训工作思考

    Institute of Scientific and Technical Information of China (English)

    申文良

    2015-01-01

    农机培训的任务是传播普及农机新技术,培训农机实用技术人才。因此县级农机校应适应形势、改变以安全生产知识和农机实用技术为主的陈旧教学方式。特别是要内强素质,外拓空间,适应农业机械全面发展的要求,加强农机高校技术和农机产业化经营知识等方面的教育培训,为造就中国新一代农民做贡献。%The task of agricultural machinery training work is to spread and popularize the new technology of agricul-tural machinery and cultivate talents proficient in practical technology ,as a result,agricultural machinery schools of coun-try-level shall be adaptive to the situation and change the mode which lay emphasis on the knowledge of safety in pro-duction and applicable technology of agricultural machinery.Internally ,they shall strengthen the quality and externally,they shall extend the scale and be adaptive to the comprehensive development of the mechanization of agriculture and strengthen the training in aspects of the industrialized management ,and make contribution for the peasants in this new generation in China.

  5. Circadian rhythms in microalgae production

    NARCIS (Netherlands)

    Winter, de L.

    2015-01-01

    Abstract Thesis: Circadian rhythms in microalgae production Lenneke de Winter The sun imposes a daily cycle of light and dark on nearly all organisms. The circadian clock evolved to help organisms program their activities at an appropriate time during this daily cycle. For example,

  6. Circadian Pacemaker – Temperature Compensation

    NARCIS (Netherlands)

    Gerkema, Menno P.; Binder, Marc D.; Hirokawa, Nobutaka; Windhorst, Uwe

    2009-01-01

    One of the defining characteristics of circadian pacemakers and indicates the independence of the speed of circadian clock processes of environmental temperature. Mechanisms involved, so far not elucidated in full detail, entail at least two processes that are similarly affected by temperature chang

  7. Circadian rhythms in microalgae production

    NARCIS (Netherlands)

    Winter, de L.

    2015-01-01

    Abstract Thesis: Circadian rhythms in microalgae production Lenneke de Winter The sun imposes a daily cycle of light and dark on nearly all organisms. The circadian clock evolved to help organisms program their activities at an appropriate time during this daily cycle. For example,

  8. 农机购置补贴政策下种稻大户购机决策影响因素分析%Analysis of Influential Factors for Big Grain Households' Purchase of Agricultural Machinery:Under the Subsidy Policy for Purchasing Agricultural Machinery

    Institute of Scientific and Technical Information of China (English)

    颜玄洲; 孙水鹅; 欧一智

    2015-01-01

    Agricultural machinery is an essential material condition for high and stable yield in agricultural production.The importance of promoting development of agricultural mechanization has been mentioned for sever-al times in the Central Committee's Document No.1 in recent years.Starting with theory of demand,this paper is designated to analyze the influential element on big grain households' purchasing machinery from both macro and micro perspectives in order to find out both macro and micro factors influencing their decision-making. So as to further verify the influential factors on big grain households' purchasing behavior,the paper then investigates 397 big grain households'sample data in Jiangxi Province by means of logistic regression models in SPSS19.0.Empir-ical study shows that planting scale,policy cognition,financing capacity,and household type have a significant influence on big grain households' purchasing agricultural machinery. And this provides a helpful instruction on how subsidy policy for purchasing machinery can be better implemented in Jiangxi Province.%农业机械是农业生产获得高产、稳产的必要物质条件,近年来中央一号文件多次提出要提高农业机械化水平. 本文从需求理论出发,从宏观和微观两方面分析江西省种稻大户购置农机的影响,从而提炼出影响种稻大户购机决策的宏观因素和微观因素,为证实在农机购置补贴政策下种稻大户购机决策的影响因素,本文利用江西省实地调查的397个种稻大户样本数据,运用SPSS19.0软件对样本进行logistic模型回归. 实证结果表明年龄、教育程度、农户类型、种植规模、政策认知、农业收入、融资能力等对于大户购置农机决策存在显著影响,进而为农机购置补贴政策更好的在江西省实施提出相应的启示.

  9. Circadian Rhythm in Cytokines Administration.

    Science.gov (United States)

    Trufakin, Valery A; Shurlygina, Anna V

    2016-01-01

    In recent times, a number of diseases involving immune system dysfunction have appeared. This increases the importance of research aimed at finding and developing optimized methods for immune system correction. Numerous studies have found a positive effect in using cytokines to treat a variety of diseases, yet the clinical use of cytokines is limited by their toxicity. Research in the field of chronotherapy, aimed at designing schedules of medicine intake using circadian biorhythms of endogenous production of factors, and receptors' expression to the factors on the target cells, as well as chronopharmacodynamics and chronopharmacokinetics of medicines may contribute to the solution of this problem. Advantages of chronotherapy include a greater effectiveness of treatment, reduced dose of required drugs, and minimized adverse effects. This review presents data on the presence of circadian rhythms of spontaneous and induced cytokine production, as well as the expression of cytokine receptors in the healthy body and in a number of diseases. The article reviews various effects of cytokines, used at different times of the day in humans and experimental animals, as well as possible mechanisms underlying the chronodependent effects of cytokines. The article presents the results of chronotherapeutic modes of administering IL-2, interferons, G-CSF, and GM-CSF in treatment of various types of cancer as well as in experimental models of immune suppression and inflammation, which lead to a greater effectiveness of therapy, the possibility of reducing or increasing the dosage, and reduced drug toxicity. Further research in this field will contribute to the effectiveness and safety of cytokine therapy.

  10. Circadian Regulation of Macronutrient Absorption.

    Science.gov (United States)

    Hussain, M Mahmood; Pan, Xiaoyue

    2015-12-01

    Various intestinal functions exhibit circadian rhythmicity. Disruptions in these rhythms as in shift workers and transcontinental travelers are associated with intestinal discomfort. Circadian rhythms are controlled at the molecular level by core clock and clock-controlled genes. These clock genes are expressed in intestinal cells, suggesting that they might participate in the circadian regulation of intestinal functions. A major function of the intestine is nutrient absorption. Here, we will review absorption of proteins, carbohydrates, and lipids and circadian regulation of various transporters involved in their absorption. A better understanding of circadian regulation of intestinal absorption might help control several metabolic disorders and attenuate intestinal discomfort associated with disruptions in sleep-wake cycles.

  11. Circadian rhythms of ocular melatonin in the wrasse Halichoeres tenuispinnis, a labrid teleost.

    Science.gov (United States)

    Iigo, Masayuki; Ikeda, Emi; Sato, Masaru; Kawasaki, Shigekatsu; Noguchi, Fumitaka; Nishi, Genjirou

    2006-01-01

    Using in vivo and in vitro methods we studied the regulation of ocular melatonin rhythms in the wrasse Halichoeres tenuispinnis, by either light or the circadian clock. Rhythmic changes in ocular melatonin levels under light-dark (LD) cycles were persistent under constant darkness (DD), and had a circadian periodicity of approximately 24h. However, ocular melatonin levels remained low under constant light conditions. When wrasse were exposed to a single 6-h light pulse at three different circadian phases under DD, phase-dependent phase shifts in the circadian rhythms of ocular melatonin were observed. When eyecups were prepared during mid-light periods or at the onset of darkness, and incubated in vitro in either light or dark periods, both time and light conditions affected melatonin release. These results indicate that the melatonin rhythms in the wrasse eye are driven by an ocular circadian clock that is entrained to LD cycles via local photoreceptors.

  12. Wheels within wheels: the plant circadian system

    Science.gov (United States)

    Hsu, Polly Yingshan; Harmer, Stacey L.

    2014-01-01

    Circadian clocks integrate environmental signals with internal cues to coordinate diverse physiological outputs so that they occur at the most appropriate season or time of day. Recent studies using systems approaches, primarily in Arabidopsis, have expanded our understanding of the molecular regulation of the central circadian oscillator and its connections to input and output pathways. Similar approaches have also begun to reveal the importance of the clock for key agricultural traits in crop species. In this review, we discuss recent developments in the field, including: a new understanding of the molecular architecture underlying the plant clock; mechanistic links between clock components and input and output pathways; and our growing understanding of the importance of clock genes for agronomically important traits. PMID:24373845

  13. Wheels within wheels: the plant circadian system.

    Science.gov (United States)

    Hsu, Polly Yingshan; Harmer, Stacey L

    2014-04-01

    Circadian clocks integrate environmental signals with internal cues to coordinate diverse physiological outputs so that they occur at the most appropriate season or time of day. Recent studies using systems approaches, primarily in Arabidopsis, have expanded our understanding of the molecular regulation of the central circadian oscillator and its connections to input and output pathways. Similar approaches have also begun to reveal the importance of the clock for key agricultural traits in crop species. In this review, we discuss recent developments in the field, including a new understanding of the molecular architecture underlying the plant clock; mechanistic links between clock components and input and output pathways; and our growing understanding of the importance of clock genes for agronomically important traits.

  14. Circadian clock, cell cycle and cancer

    Directory of Open Access Journals (Sweden)

    Cansu Özbayer

    2011-12-01

    Full Text Available There are a few rhythms of our daily lives that we are under the influence. One of them is characterized by predictable changes over a 24-hour timescale called circadian clock. This cellular clock is coordinated by the suprachiasmatic nucleus in the anterior hypothalamus. The clock consist of an autoregulatory transcription-translation feedback loop compose of four genes/proteins; BMAL1, Clock, Cyrptochrome, and Period. BMAL 1 and Clock are transcriptional factors and Period and Cyrptochrome are their targets. Period and Cyrptochrome dimerize in the cytoplasm to enter the nucleus where they inhibit Clock/BMAL activity.It has been demonstrate that circadian clock plays an important role cellular proliferation, DNA damage and repair mechanisms, checkpoints, apoptosis and cancer.

  15. Circadian rhythms and cognition.

    Science.gov (United States)

    Waterhouse, Jim

    2010-01-01

    Like all circadian (near-24-h) rhythms, those of cognition have endogenous and exogenous components. The origins of these components, together with effects of time awake upon cognitive performance, are described in subjects living conventionally (sleeping at night and active during the daytime). Based on these considerations, predictions can be made about changes that might be expected in the days after a time-zone transition and during night work. The relevant literature on these circumstances is then reviewed. The last section of the chapter deals with sleep-wake schedules where both regular and irregular sleeps are taken (anchor sleep). Copyright © 2010 Elsevier B.V. All rights reserved.

  16. MACHINERY

    African Journals Online (AJOL)

    Data were collected using a portable data acquisition system: SKF Microlog. Data were collected' ... Modelling (HMM) ofvibrational signals. ... trifugal pump designed for a pressure increase of. 6.6 bars at ..... These frequency amplitudes are located at the vertical. axial and .... distribution centre the residual chlorine concen-.

  17. A task-based analysis of machinery entanglement injuries among Western Canadian farmers.

    Science.gov (United States)

    Narasimhan, Gopinath; Crowe, Trever G; Peng, Yingwei; Hagel, Louise; Dosman, James; Pickett, William

    2011-10-01

    Machinery entanglements are a leading cause of hospitalized injury on Canadian farms. This study evaluates the role farm tasks play in the occurrence of machinery entanglement events. A retrospective case series of 41 entanglement injuries involving 35 farm-machinery types was assembled. Only a few limited tasks were implicated in the majority of entanglements. These tasks were as follows: (1) field adjustments of machinery; (2) product handling and conveyance; and (3) driveline attachments and servicing. Hazards inherent and common to these tasks affected the behavior of farmers, leading to entanglements. This study establishes a need to identify hazards and assess risks associated with different tasks involving the use of farm machinery under actual field situations. Systemic changes are required to improve existing machinery safety practices through engineering, work methods, and work practice modifications. In addition to design solutions, occupational health and safety strategies should consider activities associated with hazardous situations to inform the content of injury prevention efforts.

  18. Circadian rhythm and its role in malignancy

    OpenAIRE

    Rana, Sobia; Mahmood, Saqib

    2010-01-01

    Circadian rhythms are daily oscillations of multiple biological processes directed by endogenous clocks. The circadian timing system comprises peripheral oscillators located in most tissues of the body and a central pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus. Circadian genes and the proteins produced by these genes constitute the molecular components of the circadian oscillator which form positive/negative feedback loops and generate circadian rhythms. The circ...

  19. Circadian clocks, epigenetics, and cancer

    KAUST Repository

    Masri, Selma

    2015-01-01

    The interplay between circadian rhythm and cancer has been suggested for more than a decade based on the observations that shift work and cancer incidence are linked. Accumulating evidence implicates the circadian clock in cancer survival and proliferation pathways. At the molecular level, multiple control mechanisms have been proposed to link circadian transcription and cell-cycle control to tumorigenesis.The circadian gating of the cell cycle and subsequent control of cell proliferation is an area of active investigation. Moreover, the circadian clock is a transcriptional system that is intricately regulated at the epigenetic level. Interestingly, the epigenetic landscape at the level of histone modifications, DNA methylation, and small regulatory RNAs are differentially controlled in cancer cells. This concept raises the possibility that epigenetic control is a common thread linking the clock with cancer, though little scientific evidence is known to date.This review focuses on the link between circadian clock and cancer, and speculates on the possible connections at the epigenetic level that could further link the circadian clock to tumor initiation or progression.

  20. Absence of Circadian Rhythms of Preterm Premature Rupture of Membranes and Preterm Placental Abruption

    Science.gov (United States)

    Luque-Fernandez, Miguel Angel; Ananth, Cande V.; Sanchez, Sixto E.; Qiu, Chun-fang; Hernandez-Diaz, Sonia; Valdimarsdottir, Unnur; Gelaye, Bizu; Williams, Michelle A.

    2014-01-01

    Purpose Data regarding circadian rhythm in the onset of spontaneous preterm premature rupture of membranes (PROM) and placental abruption (PA) cases are conflicting. We modeled the time of onset of preterm PROM and PA cases and examined if the circadian profiles varied based on the gestational age at delivery. Methods We used parametric and nonparametric methods, including trigonometric regression in the framework of generalized linear models, to test the presence of circadian rhythms in the time of onset of preterm PROM and PA cases, among 395 women who delivered a singleton between 2009 and 2010 in Lima, Peru. Results We found a diurnal circadian pattern, with a morning peak at 07h:32’ (95%CI:05h:46’ – 09h:18’) among moderate preterm PROM cases (P-value<0.001), and some evidence of a diurnal circadian periodicity among PA cases in term infants (P-value=0.067). However, we did not find evidence of circadian rhythms in the time of onset of extremely or very preterm PROM (P-value=0.259) and preterm PA (P-value=0.224). Conclusions The circadian rhythms of the time of onset of preterm PROM and PA cases varied based on gestational weeks at delivery. While circadian rhythms were presented among moderate preterm PROM and term PA cases, there was no evidence of circadian rhythms among preterm PA and very or extremely preterm PROM cases, underlying other mechanisms associated with the time of onset. PMID:25453346

  1. Strategies for Improving Enterprise Standardization Management of Tropical Crop Machinery

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ There are two categories of tropical crop machinery. One comprises operation machinery that is used for planting, managing and harvesting tropical crops, while the other comprises process machinery for processing tropical crops. Tropical crop machinery is distinguished from other agricultural machinery by the special crops that such machinery cultivates and processes.

  2. Circadian rhythms and new options for novel anticancer therapies

    Directory of Open Access Journals (Sweden)

    Prosenc Zmrzljak U

    2015-01-01

    Full Text Available Ursula Prosenc ZmrzljakFaculty of Medicine, Center for Functional Genomics and Bio-Chips, Institute of Biochemistry, University of Ljubljana, Ljubljana, SloveniaAbstract: The patterns of activity/sleep, eating/fasting, etc show that our lives are under the control of an internal clock. Cancer is a systemic disease that affects sleep, feeding, and metabolism. All these processes are regulated by the circadian clock on the one hand, but on the other hand, they can serve as signals to tighten up the patient's circadian clock by robust daily routine. Usually, anticancer treatments take place in hospitals, where the patient's daily rest/activity pattern is changed. However, it has been shown that oncology patients with a disturbed circadian clock have poorer survival outcomes. The administration of different anticancer therapies can disturb the circadian cycle, but many cases show that circadian rhythms in tumors are deregulated per se. This fact can be used to plan anticancer therapies in such a manner that they will be most effective in antitumor action, but least toxic for the surrounding healthy tissue. Metabolic processes are highly regulated to prevent waste of energy and to ensure sufficient detoxification; as a consequence, xenobiotic metabolism is under tight circadian control. This gives the rationale for planning the administration of anticancer therapies in a chronomodulated manner. We review some of the potentially useful clinical praxes of anticancer therapies and discuss different possible approaches to be used in drug development and design in the future.Keywords: circadian rhythms, cancer, chronotherapy, detoxification metabolism

  3. Neurobiology of Circadian Rhythm Regulation.

    Science.gov (United States)

    Rosenwasser, Alan M; Turek, Fred W

    2015-12-01

    Over the past few decades, multilevel research has elucidated the basic neuroanatomy, neurochemistry, and molecular neurobiology of the master circadian pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). The circadian timing system is composed of a large number of cellular oscillators located in the SCN, in non-SCN brain structures, and throughout the body. Cellular-level oscillations are generated by a molecular feedback loop in which circadian clock genes rhythmically regulate their own transcription, as well as that of hundreds of clock-controlled genes. The maintenance of proper coordination within this network of cellular- and tissue-level clocks is essential for health and well-being.

  4. Nocturia: The circadian voiding disorder

    Directory of Open Access Journals (Sweden)

    Jin Wook Kim

    2016-05-01

    Full Text Available Nocturia is a prevalent condition of waking to void during the night. The concept of nocturia has evolved from being a symptomatic aspect of disease associated with the prostate or bladder to a form of lower urinary tract disorder. However, recent advances in circadian biology and sleep science suggest that it might be important to consider nocturia as a form of circadian dysfunction. In the current review, nocturia is reexamined with an introduction to sleep disorders and recent findings in circadian biology in an attempt to highlight the importance of rediscovering nocturia as a problem of chronobiology.

  5. Adaptive temperature compensation in circadian oscillations.

    Directory of Open Access Journals (Sweden)

    Paul François

    Full Text Available A temperature independent period and temperature entrainment are two defining features of circadian oscillators. A default model of distributed temperature compensation satisfies these basic facts yet is not easily reconciled with other properties of circadian clocks, such as many mutants with altered but temperature compensated periods. The default model also suggests that the shape of the circadian limit cycle and the associated phase response curves (PRC will vary since the average concentrations of clock proteins change with temperature. We propose an alternative class of models where the twin properties of a fixed period and entrainment are structural and arise from an underlying adaptive system that buffers temperature changes. These models are distinguished by a PRC whose shape is temperature independent and orbits whose extrema are temperature independent. They are readily evolved by local, hill climbing, optimization of gene networks for a common quality measure of biological clocks, phase anticipation. Interestingly a standard realization of the Goodwin model for temperature compensation displays properties of adaptive rather than distributed temperature compensation.

  6. Circadian rhythms in rat pineal melatonin synthesis Under constant darkness Conditions%持续黑暗状态下对大鼠松果体细胞分泌松果体素的昼夜节律研究

    Institute of Scientific and Technical Information of China (English)

    刘雅静; 陆仲敏; 朱红艳; 谭忠林; 周江宁

    2011-01-01

    为研究体外培养的大鼠松果体细胞分泌的松果体素是否具有内在节律,收集体外培养的大鼠松果体细胞在白天6:00,8:00,10:00,12:00,15:00,和夜晚18:00,20:00,22:00,1:00,4:00各个时间点的培养上清,并用放射免疫方法(RIA)检测各个时间点松果体细胞培养上清中的松果体素水平.CCF(complex cosine function)统计分析结果表明,在持续黑暗的环境下,体外培养的大鼠松果体细胞分泌的松果体素在培养3,6,9天后仍然表现出内在节律.然而,这种内在节律在培养12天后消失.上述结果提示体外培养的大鼠松果体细胞可以作为一个有用的体外模型来分析节律系统的生理基础.%To investigate whether rat pineal cell is capable of generating a circadian oscillation in melatonin release, the cultured pineal cell in culture medium was collected at 6 : 00, 8 : 00, 10 :00, 12 : 00 and 15 : 00 during the day, and at 18 : 00, 20 ." 00, 22 : 00, 1 : 00 and 4 : 00 at night respectively. The melatonin level in culture medium was measured by a direct radioimmunoassay.The complex cosine functions (CCF) statistical analysis indicates that the rat pineal cell melatonin synthesis shows an intrinsic rhythm at 3, 6, 9 day culture under constant dark conditions.However, the intrinsic rhythm disappears at 12 day culture. This result suggests that the rat individual pineal cells can function as a circadian oscillator in vitro.

  7. Iron is involved in the maintenance of circadian period length in Arabidopsis.

    Science.gov (United States)

    Chen, Yong-Yi; Wang, Ying; Shin, Lung-Jiun; Wu, Jing-Fen; Shanmugam, Varanavasiappan; Tsednee, Munkhtsetseg; Lo, Jing-Chi; Chen, Chyi-Chuann; Wu, Shu-Hsing; Yeh, Kuo-Chen

    2013-03-01

    The homeostasis of iron (Fe) in plants is strictly regulated to maintain an optimal level for plant growth and development but not cause oxidative stress. About 30% of arable land is considered Fe deficient because of calcareous soil that renders Fe unavailable to plants. Under Fe-deficient conditions, Arabidopsis (Arabidopsis thaliana) shows retarded growth, disordered chloroplast development, and delayed flowering time. In this study, we explored the possible connection between Fe availability and the circadian clock in growth and development. Circadian period length in Arabidopsis was longer under Fe-deficient conditions, but the lengthened period was not regulated by the canonical Fe-deficiency signaling pathway involving nitric oxide. However, plants with impaired chloroplast function showed long circadian periods. Fe deficiency and impaired chloroplast function combined did not show additive effects on the circadian period, which suggests that plastid-to-nucleus retrograde signaling is involved in the lengthening of circadian period under Fe deficiency. Expression pattern analyses of the central oscillator genes in mutants defective in CIRCADIAN CLOCK ASSOCIATED1/LATE ELONGATED HYPOCOTYL or GIGANTEA demonstrated their requirement for Fe deficiency-induced long circadian period. In conclusion, Fe is involved in maintaining the period length of circadian rhythm, possibly by acting on specific central oscillators through a retrograde signaling pathway.

  8. Iron Is Involved in the Maintenance of Circadian Period Length in Arabidopsis12[W][OA

    Science.gov (United States)

    Chen, Yong-Yi; Wang, Ying; Shin, Lung-Jiun; Wu, Jing-Fen; Shanmugam, Varanavasiappan; Tsednee, Munkhtsetseg; Lo, Jing-Chi; Chen, Chyi-Chuann; Wu, Shu-Hsing; Yeh, Kuo-Chen

    2013-01-01

    The homeostasis of iron (Fe) in plants is strictly regulated to maintain an optimal level for plant growth and development but not cause oxidative stress. About 30% of arable land is considered Fe deficient because of calcareous soil that renders Fe unavailable to plants. Under Fe-deficient conditions, Arabidopsis (Arabidopsis thaliana) shows retarded growth, disordered chloroplast development, and delayed flowering time. In this study, we explored the possible connection between Fe availability and the circadian clock in growth and development. Circadian period length in Arabidopsis was longer under Fe-deficient conditions, but the lengthened period was not regulated by the canonical Fe-deficiency signaling pathway involving nitric oxide. However, plants with impaired chloroplast function showed long circadian periods. Fe deficiency and impaired chloroplast function combined did not show additive effects on the circadian period, which suggests that plastid-to-nucleus retrograde signaling is involved in the lengthening of circadian period under Fe deficiency. Expression pattern analyses of the central oscillator genes in mutants defective in CIRCADIAN CLOCK ASSOCIATED1/LATE ELONGATED HYPOCOTYL or GIGANTEA demonstrated their requirement for Fe deficiency-induced long circadian period. In conclusion, Fe is involved in maintaining the period length of circadian rhythm, possibly by acting on specific central oscillators through a retrograde signaling pathway. PMID:23307650

  9. Facilitated physiological adaptation to prolonged circadian disruption through dietary supplementation with essence of chicken.

    Science.gov (United States)

    Wu, Tao; Yao, Cencen; Tsang, Fai; Huang, Liangfeng; Zhang, Wanjing; Jiang, Jianguo; Mao, Youxiang; Shao, Yujian; Kong, Boda; Singh, Paramjeet; Fu, Zhengwei

    2015-01-01

    Synchrony between circadian and metabolic processes is critical to the maintenance of energy homeostasis. Studies on essence of chicken (EC), a chicken meat extract rich in proteins, amino acids and peptides, showed its effectiveness in alleviating fatigue and promoting metabolism. A recent study revealed that it facilitated the re-entrainment of clock genes (Bmal1, Cry1, Dec1, Per1 and Per2) in the pineal gland and liver in a rat model of circadian disruption. Here, we investigated the role of EC-facilitated circadian synchrony in the maintenance of the energy homeostasis using a mouse model of prolonged circadian disruption. Prolonged circadian disruption (12 weeks) resulted in hepatic maladaptation, manifested by a mild but significant (p < 0.05) hepatomegaly, accompanied by disturbed hepatic lipid metabolism and liver injury (indicated by increased circulating hepatic enzymes). Evidently, there was marked elevations of hepatic inflammatory mediators (interleukin-1beta and interleukin-6), suggesting an underlying inflammation leading to the hepatic injury and functional impairment. Importantly, the disruption paradigm caused the decoupling between key metabolic regulators (e.g. mTOR and AMPK) and hepatic clock genes (Per1, Cry1, Dec1, Bmal1). Further, we showed that the loss of circadian synchrony between the master and hepatic clock genes (Per1, Cry1, Dec1, Bmal1) could be the underlying cause of the maladaptation. When supplemented with EC, the functional impairment and inflammation were abolished. The protective effects could be linked to its effectiveness in maintaining the synchrony between the master and hepatic clocks, and the resultant improved coupling of the circadian oscillators (Per1, Cry1, Dec1, Bmal1) and metabolic regulators (mTOR, AMPK). Overall, EC supplementation promoted the physiological adaptation to the prolonged circadian disruption through facilitation of endogenous circadian synchrony and the coupling of circadian oscillators and

  10. Plasticity of the intrinsic period of the human circadian timing system.

    Directory of Open Access Journals (Sweden)

    Frank A J L Scheer

    Full Text Available Human expeditions to Mars will require adaptation to the 24.65-h Martian solar day-night cycle (sol, which is outside the range of entrainment of the human circadian pacemaker under lighting intensities to which astronauts are typically exposed. Failure to entrain the circadian time-keeping system to the desired rest-activity cycle disturbs sleep and impairs cognitive function. Furthermore, differences between the intrinsic circadian period and Earth's 24-h light-dark cycle underlie human circadian rhythm sleep disorders, such as advanced sleep phase disorder and non-24-hour sleep-wake disorders. Therefore, first, we tested whether exposure to a model-based lighting regimen would entrain the human circadian pacemaker at a normal phase angle to the 24.65-h Martian sol and to the 23.5-h day length often required of astronauts during short duration space exploration. Second, we tested here whether such prior entrainment to non-24-h light-dark cycles would lead to subsequent modification of the intrinsic period of the human circadian timing system. Here we show that exposure to moderately bright light ( approximately 450 lux; approximately 1.2 W/m(2 for the second or first half of the scheduled wake episode is effective for entraining individuals to the 24.65-h Martian sol and a 23.5-h day length, respectively. Estimations of the circadian periods of plasma melatonin, plasma cortisol, and core body temperature rhythms collected under forced desynchrony protocols revealed that the intrinsic circadian period of the human circadian pacemaker was significantly longer following entrainment to the Martian sol as compared to following entrainment to the 23.5-h day. The latter finding of after-effects of entrainment reveals for the first time plasticity of the period of the human circadian timing system. Both findings have important implications for the treatment of circadian rhythm sleep disorders and human space exploration.

  11. Circadian Reprogramming in the Liver Identifies Metabolic Pathways of Aging.

    Science.gov (United States)

    Sato, Shogo; Solanas, Guiomar; Peixoto, Francisca Oliveira; Bee, Leonardo; Symeonidi, Aikaterini; Schmidt, Mark S; Brenner, Charles; Masri, Selma; Benitah, Salvador Aznar; Sassone-Corsi, Paolo

    2017-08-10

    The process of aging and circadian rhythms are intimately intertwined, but how peripheral clocks involved in metabolic homeostasis contribute to aging remains unknown. Importantly, caloric restriction (CR) extends lifespan in several organisms and rewires circadian metabolism. Using young versus old mice, fed ad libitum or under CR, we reveal reprogramming of the circadian transcriptome in the liver. These age-dependent changes occur in a highly tissue-specific manner, as demonstrated by comparing circadian gene expression in the liver versus epidermal and skeletal muscle stem cells. Moreover, de novo oscillating genes under CR show an enrichment in SIRT1 targets in the liver. This is accompanied by distinct circadian hepatic signatures in NAD(+)-related metabolites and cyclic global protein acetylation. Strikingly, this oscillation in acetylation is absent in old mice while CR robustly rescues global protein acetylation. Our findings indicate that the clock operates at the crossroad between protein acetylation, liver metabolism, and aging. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. The circadian clock has transient plasticity of period and is required for timing of nocturnal processes in Arabidopsis.

    Science.gov (United States)

    Dodd, Antony N; Dalchau, Neil; Gardner, Michael J; Baek, Seong-Jin; Webb, Alex A R

    2014-01-01

    A circadian rhythm matched to the phase and period of the day-night cycle has measurable benefits for land plants. We assessed the contribution of circadian period to the phasing of cellular events with the light : dark cycle. We also investigated the plasticity of circadian period within the Arabidopsis circadian oscillator. We monitored the circadian oscillator in wild-type and circadian period mutants under light : dark cycles of varying total duration. We also investigated changes in oscillator dynamics during and after the transition from light : dark cycles to free running conditions. Under light : dark cycles, dawn and dusk were anticipated differently when the circadian period was not resonant with the environmental period ('T cycle'). Entrainment to T cycles differing from the free-running period caused a short-term alteration in oscillator period. The transient plasticity of period was described by existing mathematical models of the Arabidopsis circadian network. We conclude that a circadian period resonant with the period of the environment is particularly important for anticipation of dawn and the timing of nocturnal events; and there is short-term and transient plasticity of period of the Arabidopsis circadian network.

  13. Inositols affect the mating circadian rhythm of Drosophila melanogaster

    Science.gov (United States)

    Sakata, Kazuki; Kawasaki, Haruhisa; Suzuki, Takahiro; Ito, Kumpei; Negishi, Osamu; Tsuno, Takuo; Tsuno, Hiromi; Yamazaki, Youta; Ishida, Norio

    2015-01-01

    Accumulating evidence indicates that the molecular circadian clock underlies the mating behavior of Drosophila melanogaster. However, information about which food components affect circadian mating behavior is scant. The ice plant, Mesembryanthemum crystallinum has recently become a popular functional food. Here, we showed that the close-proximity (CP) rhythm of D. melanogaster courtship behavior was damped under low-nutrient conditions, but significantly enhanced by feeding the flies with powdered ice plant. Among various components of ice plants, we found that myo-inositol increased the amplitude and slightly shortened the period of the CP rhythm. Real-time reporter assays showed that myo-inositol and D-pinitol shortened the period of the circadian reporter gene Per2-luc in NIH 3T3 cells. These data suggest that the ice plant is a useful functional food and that the ability of inositols to shorten rhythms is a general phenomenon in insects as well as mammals. PMID:26097456

  14. Inositols affect the mating circadian rhythm of Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Kazuki eSakata

    2015-06-01

    Full Text Available Accumulating evidence indicates that the molecular circadian clock underlies the mating behavior of D. melanogaster. However, information about which food components affect circadian mating behavior is scant. The ice plant, Mesembryanthemum crystallinum has recently become a popular functional food. Here, we showed that the close-proximity (CP rhythm of Drosophila melanogaster courtship behavior was damped under low-nutrient conditions, but significantly enhanced by feeding the flies with powdered ice plant. Among various components of ice plants, we found that myo-inositol increased the amplitude and slightly shortened the period of the CP rhythm. Real-time reporter assays showed that myo-inositol and D-pinitol shortened the period of the circadian reporter gene Per2-luc in NIH 3T3 cells. These data suggest that the ice plant is a useful functional food and that the ability of inositols to shorten rhythms is a general phenomenon in insects as well as mammals.

  15. The circadian clock goes genomic.

    Science.gov (United States)

    Staiger, Dorothee; Shin, Jieun; Johansson, Mikael; Davis, Seth J

    2013-06-24

    Large-scale biology among plant species, as well as comparative genomics of circadian clock architecture and clock-regulated output processes, have greatly advanced our understanding of the endogenous timing system in plants.

  16. Circadian preference in bipolar disorder.

    Science.gov (United States)

    Giglio, Larriany Maria Falsin; Magalhães, Pedro V S; Andersen, Mônica Levy; Walz, Julio Cesar; Jakobson, Lourenço; Kapczinski, Flávio

    2010-06-01

    A role for circadian rhythm abnormalities in the pathogenesis of bipolar disorder (BD) has been suggested. The present study assessed circadian preference, a subjective preference for activities in the morning or evening related to chronotype. The sample was comprised of 81 outpatients with BD in remission and 79 control subjects. Circadian preference was derived from an interview evaluating biological rhythms and sleep pattern from the Pittsburgh Sleep Quality Index. Patients were significantly more likely to have an evening preference than control subjects. Circadian preference was also associated with sleep latency. The association of evening preference and longer sleep latency may be related to the frequent clinical observation of a sleep/wake cycle reversal in bipolar disorder.

  17. Circadian Influences on Myocardial Infarction

    Directory of Open Access Journals (Sweden)

    Jitka A. I. Virag

    2014-10-01

    Full Text Available Components of circadian rhythm maintenance, or clock genes, are found in all peripheral tissues, including the heart, and influence such diverse phenomena as cytokine expression immune cells, metabolic activity of cardiac myocytes, and vasodilator regulation by vascular endothelial cells. Whether circadian patterns are causally related to the observed periodicity of events, or whether they are simply epi-phenomena is not well established, but a few studies suggest that the circadian effects likely are real in their impact on cardiovascular disease incidence. Cycle disturbances may be harbingers of predisposition and subsequent response to acute and chronic cardiac injury, and identifying the complex interactions of circadian rhythms and cardiovascular disease may provide insights into possible preventative and therapeutic strategies for susceptible populations.

  18. Circadian Rhythm Management System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The value of measuring sleep-wake cycles is significantly enhanced by measuring other physiological signals that depend on circadian rhythms (such as heart rate and...

  19. Aircrew fatigue and circadian rhythmicity

    Science.gov (United States)

    Graeber, R. Curtis

    1988-01-01

    Recent statistical and experimental studies on the role of circadian rhythms in aircrew fatigue and aviation accidents are reviewed from a human-factors perspective, and typical data are presented in extensive graphs. Consideration is given to the biological clock and the limits of endurance, circadian desynchronization, sleep and sleepiness, short-haul and long-haul operational studies, and the potential advantages of cockpit automation.

  20. Circadian clock and cardiac vulnerability: A time stamp on multi-scale neuroautonomic regulation

    Science.gov (United States)

    Ivanov, Plamen Ch.

    2005-03-01

    Cardiovascular vulnerability displays a 24-hour pattern with a peak between 9AM and 11AM. This daily pattern in cardiac risk is traditionally attributed to external factors including activity levels and sleep-wake cycles. However,influences from the endogenous circadian pacemaker independent from behaviors may also affect cardiac control. We investigate heartbeat dynamics in healthy subjects recorded throughout a 10-day protocol wherein the sleep/wake and behavior cycles are desynchronized from the endogenous circadian cycle,enabling assessment of circadian factors while controlling for behavior-related factors. We demonstrate that the scaling exponent characterizing temporal correlations in heartbeat dynamics over multiple time scales does exhibit a significant circadian rhythm with a sharp peak at the circadian phase corresponding to the period 9-11AM, and that this rhythm is independent from scheduled behaviors and mean heart rate. Our findings of strong circadian rhythms in the multi-scale heartbeat dynamics of healthy young subjects indicate that the underlying mechanism of cardiac regulation is strongly influenced by the endogenous circadian pacemaker. A similar circadian effect in vulnerable individuals with underlying cardiovascular disease would contribute to the morning peak of adverse cardiac events observed in epidemiological studies.

  1. Environmental circadian disruption elevates the IL-6 response to lipopolysaccharide in blood.

    Science.gov (United States)

    Adams, Kandis L; Castanon-Cervantes, Oscar; Evans, Jennifer A; Davidson, Alec J

    2013-08-01

    The immune system is regulated by circadian clocks within the brain and immune cells. Environmental circadian disruption (ECD), consisting of a 6-h phase advance of the light:dark cycle once a week for 4 weeks, elevates the inflammatory response to lipopolysaccharide (LPS) both in vivo and in vitro. This indicates that circadian disruption adversely affects immune function; however, it remains unclear how the circadian system regulates this response under ECD conditions. Here, we develop an assay using ex vivo whole-blood LPS challenge to investigate the circadian regulation of immune responses in mice and to determine the effects of ECD on these rhythms. LPS-induced IL-6 release in whole blood was regulated in a circadian manner, peaking during subjective day under both entrained and free-running conditions. This LPS-induced IL-6 release rhythm was associated with daily variation in both white blood cell counts and immune cell responsiveness. ECD increased the overall level of LPS-induced IL-6 release by increasing immune cell responsiveness and not by affecting immune cell number or the circadian regulation of this rhythm. This indicates that ECD produces pathological immune responses by increasing the proinflammatory responses of immune cells. Also, this newly developed whole blood assay can provide a noninvasive longitudinal method to quantify potential health consequences of circadian disruption in humans.

  2. Ketamine influences CLOCK:BMAL1 function leading to altered circadian gene expression.

    Directory of Open Access Journals (Sweden)

    Marina M Bellet

    Full Text Available Major mood disorders have been linked to abnormalities in circadian rhythms, leading to disturbances in sleep, mood, temperature, and hormonal levels. We provide evidence that ketamine, a drug with rapid antidepressant effects, influences the function of the circadian molecular machinery. Ketamine modulates CLOCK:BMAL1-mediated transcriptional activation when these regulators are ectopically expressed in NG108-15 neuronal cells. Inhibition occurs in a dose-dependent manner and is attenuated after treatment with the GSK3β antagonist SB21673. We analyzed the effect of ketamine on circadian gene expression and observed a dose-dependent reduction in the amplitude of circadian transcription of the Bmal1, Per2, and Cry1 genes. Finally, chromatin-immunoprecipitation analyses revealed that ketamine altered the recruitment of the CLOCK:BMAL1 complex on circadian promoters in a time-dependent manner. Our results reveal a yet unsuspected molecular mode of action of ketamine and thereby may suggest possible pharmacological antidepressant strategies.

  3. Developing Process of Tropical Crop Machinery Standardization

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ General Situation Tropical crop machinery is a new special mechanical profession, which began to develop from 1950s to 1960s in China. Because the weather, soil and farm crops varieties in tropical region are greatly different from those in the other regions, most of the traditional farm machinery can't be directly used in tropical region or on the tropical crops. Tropical crop machinery needs a special design and manufacture. So some professional research institutes and education units were set up and some enterprises were built at that time, and the profession of tropical crop machinery was formed.

  4. Membrane manipulations by the ESCRT machinery.

    Science.gov (United States)

    Odorizzi, Greg

    2015-01-01

    The endosomal sorting complexes required for transport (ESCRTs) collectively comprise a machinery that was first known for its function in the degradation of transmembrane proteins in the endocytic pathway of eukaryotic cells. Since their discovery, however, ESCRTs have been recognized as playing important roles at the plasma membrane, which appears to be the original site of function for the ESCRT machinery. This article reviews some of the major research findings that have shaped our current understanding of how the ESCRT machinery controls membrane dynamics and considers new roles for the ESCRT machinery that might be driven by these mechanisms.

  5. Effects of square-wave and simulated natural light-dark cycles on hamster circadian rhythms

    Science.gov (United States)

    Tang, I. H.; Murakami, D. M.; Fuller, C. A.

    1999-01-01

    Circadian rhythms of activity (Act) and body temperature (Tb) were recorded from male Syrian hamsters under square-wave (LDSq) and simulated natural (LDSN, with dawn and dusk transitions) light-dark cycles. Light intensity and data sampling were under the synchronized control of a laboratory computer. Changes in reactive and predictive onsets and offsets for the circadian rhythms of Act and Tb were examined in both lighting conditions. The reactive Act onset occurred 1.1 h earlier (P circadian entrainment characteristics under LDSq and LDSN, suggesting that gradual and abrupt transitions between light and dark may provide different temporal cues.

  6. Oils degradation in agricultural machinery

    Directory of Open Access Journals (Sweden)

    Vojtěch Kumbár

    2013-01-01

    Full Text Available Evaluating of oils condition in agricultural machinery is very important. With monitoring and evaluating we can prevent technical and economic losses. In this paper there were monitored the liquid lubricants taken from mobile thresher New Holland CX 860. Chemical and viscosity degradation of the lubricants were evaluated. Temperature dependence dynamic viscosity was observed in the range of temperature from −10 °C to 80 °C (for all oils. Considerable temperature dependence dynamic viscosity was found and demonstrated in case of all samples, which is in accordance with theoretical assumptions and literature data. Mathematical models were developed and tested. Temperature dependence dynamic viscosity was modeled using a polynomial 6th degree. The proposed models can be used for prediction of flow behavior of oils.

  7. GRK2: putting the brakes on the circadian clock

    Science.gov (United States)

    Mendoza-Viveros, Lucia; Cheng, Arthur H.

    2016-01-01

    G protein-coupled receptor kinases (GRKs) are a family of serine/threonine protein kinases that terminate G protein-coupled receptor (GPCR) signaling by phosphorylating the receptor and inducing its internalization. In addition to their canonical function, some GRKs can phosphorylate non-GPCR substrates and regulate GPCR signaling in a kinase-independent manner. GPCRs are abundantly expressed in the suprachiasmatic nucleus (SCN), a structure in the mammalian brain that serves as the central circadian pacemaker. Various facets of circadian timekeeping are under the influence of GPCR signaling, and thus are potential targets for GRK regulation. Despite this, little attention has been given to the role of GRKs in circadian rhythms. In this research highlight, we discuss our latest findings on the functional involvement of GRK2 in mammalian circadian timekeeping in the SCN. Using grk2 knockout mice, we demonstrate that GRK2 is critical for maintaining proper clock speed and ensuring that the clock is appropriately synchronized to environmental light cycles. Although grk2 deficiency expectedly alters the expression of a key GPCR in the SCN, our study also reveals that GRK2 has a more direct function that touches the heart of the circadian clock. PMID:27088110

  8. Blood transcriptome based biomarkers for human circadian phase

    Science.gov (United States)

    Laing, Emma E; Möller-Levet, Carla S; Poh, Norman; Santhi, Nayantara; Archer, Simon N; Dijk, Derk-Jan

    2017-01-01

    Diagnosis and treatment of circadian rhythm sleep-wake disorders both require assessment of circadian phase of the brain’s circadian pacemaker. The gold-standard univariate method is based on collection of a 24-hr time series of plasma melatonin, a suprachiasmatic nucleus-driven pineal hormone. We developed and validated a multivariate whole-blood mRNA-based predictor of melatonin phase which requires few samples. Transcriptome data were collected under normal, sleep-deprivation and abnormal sleep-timing conditions to assess robustness of the predictor. Partial least square regression (PLSR), applied to the transcriptome, identified a set of 100 biomarkers primarily related to glucocorticoid signaling and immune function. Validation showed that PLSR-based predictors outperform published blood-derived circadian phase predictors. When given one sample as input, the R2 of predicted vs observed phase was 0.74, whereas for two samples taken 12 hr apart, R2 was 0.90. This blood transcriptome-based model enables assessment of circadian phase from a few samples. DOI: http://dx.doi.org/10.7554/eLife.20214.001 PMID:28218891

  9. CREB influences timing and entrainment of the SCN circadian clock.

    Science.gov (United States)

    Lee, Boyoung; Li, Aiqing; Hansen, Katelin F; Cao, Ruifeng; Yoon, Jae Hwa; Obrietan, Karl

    2010-12-01

    The transcriptional feedback circuit, which is at the core of the suprachiasmatic nucleus (SCN) circadian (i.e., 24 h) clock, is tightly coupled to both external entrainment cues, such as light, as well as rhythmic cues that arise on a system-wide level within the SCN. One potential signaling pathway by which these cues are conveyed to the molecular clock is the CREB/CRE transcriptional cascade. In this study, we employed a tetracycline-inducible CREB repressor mouse strain, in which approximately 60% of the SCN neurons express the transgene, to test CREB functionality in the clock and its effects on overt rhythmicity. We show that attenuated CREB signaling in the SCN led to a significant reduction in light-evoked clock entrainment. An examination of circadian timing revealed that CREB repressor mice exhibited normal free-running rhythms in the absence of external lighting cues. However, under conditions of constant light, which typically leads to a lengthening of the circadian period, CREB repressor mice exhibited a dramatic arrhythmic phenotype, which could be reversed with doxycycline. At a cellular level, the repression of CREB led to a significant reduction in both the expression of the circadian clock proteins PERIOD1 and PERIOD2 and the clock output hormones AVP and VIP. Together, these data support the idea that the CRE transcriptional pathway orchestrates transcriptional events that are essential for both the maintenance of SCN timing and light entrainment of the circadian clock.

  10. FOREWORD: 26th IAHR Symposium on Hydraulic Machinery and Systems

    Science.gov (United States)

    Wu, Yulin; Wang, Zhengwei; Liu, Shuhong; Yuan, Shouqi; Luo, Xingqi; Wang, Fujun

    2012-11-01

    the value of hydraulic machinery to the end user, to the societies, and to improve societies understanding and appreciation of that value. The series of IAHR Symposia on Hydraulic Machinery and Cavitation started with the 1st edition in Nice, France, 1960. For the past decade, all the symposia have focused on an extended portfolio of topics under the name of 'Hydraulic Machinery and Systems', such as the 20th edition in Charlotte, USA, 2000, the 21st in Lausanne, Switzerland, 2002, the 22nd in Stockholm, Sweden, 2004, the 23rd in Yokohama, Japan, 2006, the 24th in Foz do Iguassu, Brasil, 2008, and the 25th in Timisoara, Romania, 2010. The 26th IAHR Symposium on Hydraulic Machinery and Systems brings together more than 250 scientists and researchers from 25 countries, affiliated with universities, technology centers and industrial firms to debate topics related to advanced technologies for hydraulic machinery and systems, which will enhance the sustainable development of water resources and hydropower production. The Scientific Committee has selected 268 papers, out of 430 abstracts submitted, on the following topics: (i) Hydraulic Turbines and Pumps, (ii) Sustainable Hydropower, (iii) Hydraulic Systems, (iv) Advances in Computational and Experimental Techniques, (v) Application in Industries and in Special Conditions, to be presented at the symposium and to be included in the proceedings. All the papers, published in this Volume 15 of IOP Conference Series: Earth and Environmental Science, have been peer reviewed through processes administered by the editors of the 26th IAHR Symposium on Hydraulic Machinery and Systems proceedings, those are Yulin Wu, Zhengwei Wang, Shuhong Liu, Shouqi Yuan, Xingqi Luo and Fujun Wang. We sincerely hope that this edition of the symposium will be a significant step forward in the worldwide efforts to address the present challenges facing the modern Hydraulic Machinery and Systems. Professor Yulin Wu Chairman of the Organizing Committee

  11. Research on the Planning Process Optimization of Woodworking Machinery Enterprises under Condition of ERP%ERP环境下木工机械企业生产计划流程优化研究

    Institute of Scientific and Technical Information of China (English)

    明海蓉; 于粤

    2013-01-01

    Strengthen the woodworking machinery enterprises planning management is of great significance for the company to reduce costs and meet the needs of the market. So they can be more competitive. This paper is based on the present Features of the woodworking machinery industry, discuss from how to formulate the strategic plans to divide them into plans in detail which can be realized and controlled. And then finally the planning process will be explained in details.%  加强木工机械企业生产计划管理,对于企业降低生产成本,满足市场需求,增强企业竞争能力有重大意义。针对木工机械行业现状,从企业ERP系统战略计划制定出发,到分解成作业计划相关流程的分析及控制流程分析,提出优化的计划及控制流程,并对优化计划流程进行详细说明。

  12. Circadian rhythms in depression and recovery: evidence for blunted amplitude as the main chronobiological abnormality.

    Science.gov (United States)

    Souêtre, E; Salvati, E; Belugou, J L; Pringuey, D; Candito, M; Krebs, B; Ardisson, J L; Darcourt, G

    1989-06-01

    Circadian rhythms of body temperature, plasma cortisol, norepinephrine (NE), thyroid stimulating hormone (TSH), and melatonin were compared in 16 endogenously depressed, 15 recovered (after 3 weeks of anti-depressant treatment), and 16 normal subjects. The depressed patients showed clear circadian rhythm abnormalities, consisting mainly in amplitude reduction. This amplitude reduction was significantly correlated with the patients' Hamilton depression scores. Normal circadian profiles were restored after recovery when amplitude, in particular, was increased. Features of the circadian rhythms observed in remission may be associated with antidepressant drug effects, whereas those observed in depression resemble the circadian rhythms observed in normal subjects living under conditions of temporal isolation and those of blind subjects. Our findings suggest that depression may be related both to a weakening of the coupling processes between internal pacemakers and to an abnormal sensitivity to environmental information.

  13. Domestication selected for deceleration of the circadian clock in cultivated tomato.

    Science.gov (United States)

    Müller, Niels A; Wijnen, Cris L; Srinivasan, Arunkumar; Ryngajllo, Malgorzata; Ofner, Itai; Lin, Tao; Ranjan, Aashish; West, Donnelly; Maloof, Julin N; Sinha, Neelima R; Huang, Sanwen; Zamir, Dani; Jiménez-Gómez, José M

    2016-01-01

    The circadian clock is a critical regulator of plant physiology and development, controlling key agricultural traits in crop plants. In addition, natural variation in circadian rhythms is important for local adaptation. However, quantitative modulation of circadian rhythms due to artificial selection has not yet been reported. Here we show that the circadian clock of cultivated tomato (Solanum lycopersicum) has slowed during domestication. Allelic variation of the tomato homolog of the Arabidopsis gene EID1 is responsible for a phase delay. Notably, the genomic region harboring EID1 shows signatures of a selective sweep. We find that the EID1 allele in cultivated tomatoes enhances plant performance specifically under long day photoperiods, suggesting that humans selected slower circadian rhythms to adapt the cultivated species to the long summer days it encountered as it was moved away from the equator.

  14. Circadian period integrates network information through activation of the BMP signaling pathway.

    Science.gov (United States)

    Beckwith, Esteban J; Gorostiza, E Axel; Berni, Jimena; Rezával, Carolina; Pérez-Santángelo, Agustín; Nadra, Alejandro D; Ceriani, María Fernanda

    2013-12-01

    Living organisms use biological clocks to maintain their internal temporal order and anticipate daily environmental changes. In Drosophila, circadian regulation of locomotor behavior is controlled by ∼150 neurons; among them, neurons expressing the PIGMENT DISPERSING FACTOR (PDF) set the period of locomotor behavior under free-running conditions. To date, it remains unclear how individual circadian clusters integrate their activity to assemble a distinctive behavioral output. Here we show that the BONE MORPHOGENETIC PROTEIN (BMP) signaling pathway plays a crucial role in setting the circadian period in PDF neurons in the adult brain. Acute deregulation of BMP signaling causes period lengthening through regulation of dClock transcription, providing evidence for a novel function of this pathway in the adult brain. We propose that coherence in the circadian network arises from integration in PDF neurons of both the pace of the cell-autonomous molecular clock and information derived from circadian-relevant neurons through release of BMP ligands.

  15. Dissecting differential gene expression within the circadian neuronal circuit of Drosophila

    Science.gov (United States)

    Nagoshi, Emi; Sugino, Ken; Kula, Ela; Okazaki, Etsuko; Tachibana, Taro; Nelson, Sacha; Rosbash, Michael

    2013-01-01

    Behavioral circadian rhythms are controlled by a neuronal circuit consisting of diverse neuronal subgroups. To understand the molecular mechanisms underlying the roles of neuronal subgroups within the Drosophila circadian circuit, we used cell-type specific gene-expression profiling and identified a large number of genes specifically expressed in all clock neurons or in two important subgroups. Moreover, we identified and characterized two circadian genes, which are expressed specifically in subsets of clock cells and affect different aspects of rhythms. The transcription factor Fer2 is expressed in ventral lateral neurons; it is required for the specification of lateral neurons and therefore their ability to drive locomotor rhythms. The Drosophila melanogaster homolog of the vertebrate circadian gene nocturnin is expressed in a subset of dorsal neurons and mediates the circadian light response. The approach should also enable the molecular dissection of many different Drosophila neuronal circuits. PMID:19966839

  16. Cross-talk between circadian clocks, sleep-wake cycles, and metabolic networks: Dispelling the darkness.

    Science.gov (United States)

    Ray, Sandipan; Reddy, Akhilesh B

    2016-04-01

    Integration of knowledge concerning circadian rhythms, metabolic networks, and sleep-wake cycles is imperative for unraveling the mysteries of biological cycles and their underlying mechanisms. During the last decade, enormous progress in circadian biology research has provided a plethora of new insights into the molecular architecture of circadian clocks. However, the recent identification of autonomous redox oscillations in cells has expanded our view of the clockwork beyond conventional transcription/translation feedback loop models, which have been dominant since the first circadian period mutants were identified in fruit fly. Consequently, non-transcriptional timekeeping mechanisms have been proposed, and the antioxidant peroxiredoxin proteins have been identified as conserved markers for 24-hour rhythms. Here, we review recent advances in our understanding of interdependencies amongst circadian rhythms, sleep homeostasis, redox cycles, and other cellular metabolic networks. We speculate that systems-level investigations implementing integrated multi-omics approaches could provide novel mechanistic insights into the connectivity between daily cycles and metabolic systems.

  17. The hormonal Zeitgeber melatonin: Role as a circadian modulator in memory processing

    Directory of Open Access Journals (Sweden)

    Oliver eRawashdeh

    2012-03-01

    Full Text Available The neuroendocrine substance melatonin is a hormone synthesized rhythmically by the pineal gland under the influence of the circadian system and alternating light/dark cycles. Melatonin has been shown to have broad applications, and consequently becoming a molecule of great controversy. Undoubtedly, however, melatonin plays an important role as a time cue for the endogenous circadian system. This review focuses on melatonin as a regulator in the circadian modulation of memory processing. Memory processes (acquisition, consolidation and retrieval are modulated by the circadian system. However, the mechanism by which the biological clock is rhythmically influencing cognitive processes remains unknown. We also discuss, how the circadian system by generating cycling melatonin levels can implant information about daytime into memory processing, depicted as day and nighttime differences in acquisition, memory consolidation and/or retrieval.

  18. Circadian period integrates network information through activation of the BMP signaling pathway.

    Directory of Open Access Journals (Sweden)

    Esteban J Beckwith

    2013-12-01

    Full Text Available Living organisms use biological clocks to maintain their internal temporal order and anticipate daily environmental changes. In Drosophila, circadian regulation of locomotor behavior is controlled by ∼150 neurons; among them, neurons expressing the PIGMENT DISPERSING FACTOR (PDF set the period of locomotor behavior under free-running conditions. To date, it remains unclear how individual circadian clusters integrate their activity to assemble a distinctive behavioral output. Here we show that the BONE MORPHOGENETIC PROTEIN (BMP signaling pathway plays a crucial role in setting the circadian period in PDF neurons in the adult brain. Acute deregulation of BMP signaling causes period lengthening through regulation of dClock transcription, providing evidence for a novel function of this pathway in the adult brain. We propose that coherence in the circadian network arises from integration in PDF neurons of both the pace of the cell-autonomous molecular clock and information derived from circadian-relevant neurons through release of BMP ligands.

  19. Unwinding the molecular basis of interval and circadian timing

    Directory of Open Access Journals (Sweden)

    Patricia V. Agostino

    2011-10-01

    Full Text Available Neural timing mechanisms range from the millisecond to diurnal, and possibly annual, frequencies. Two of the main processes under study are the interval timer (seconds-to-minute range and the circadian clock. The molecular basis of these two mechanisms is the subject of intense research, as well as their possible relationship. This article summarizes data from studies investigating a possible interaction between interval and circadian timing and reviews the molecular basis of both mechanisms, including the discussion of the contribution from studies of genetically modified animal models. While a common neurochemical substrate for timing mechanisms in the brain has been related to dopamine-reward systems, circadian modulation of interval timing suggests an interaction of different frequencies in cerebral temporal processes.

  20. Arabidopsis circadian clock and photoperiodism: time to think about location.

    Science.gov (United States)

    Imaizumi, Takato

    2010-02-01

    Plants possess a circadian clock that enables them to coordinate internal biological events with external daily changes. Recent studies in Arabidopsis revealed that tissue-specific clock components exist and that the clock network architecture also varies within different organs. These findings indicate that the makeup of circadian clock(s) within a plant is quite variable. Plants utilize the circadian clock to measure day-length changes for regulating seasonal responses, such as flowering. To ensure that flowering occurs under optimum conditions, the clock regulates diurnal CONSTANS (CO) expression. Subsequently, CO protein induces FLOWERING LOCUS T (FT) expression which leads to flowering. It is emerging that both CO and FT expression are intricately controlled by groups of transcription factors with overlapping functions. Copyright 2009 Elsevier Ltd. All rights reserved.

  1. High fat diet and in utero exposure to maternal obesity disrupts circadian rhythm and leads to metabolic programming of liver in rat offspring.

    Directory of Open Access Journals (Sweden)

    Sarah J Borengasser

    Full Text Available The risk of obesity in adulthood is subject to programming beginning at conception. In animal models, exposure to maternal obesity and high fat diets influences the risk of obesity in the offspring. Among other long-term changes, offspring from obese rats develop hyperinsulinemia, hepatic steatosis, and lipogenic gene expression in the liver at weaning. However, the precise underlying mechanisms leading to metabolic dysregulation in the offspring remains unclear. Using a rat model of overfeeding-induced obesity, we previously demonstrated that exposure to maternal obesity from pre-conception to birth, is sufficient to program increased obesity risk in the offspring. Offspring of obese rat dams gain greater body weight and fat mass when fed high fat diet (HFD as compared to lean dam. Since, disruptions of diurnal circadian rhythm are known to detrimentally impact metabolically active tissues such as liver, we examined the hypothesis that maternal obesity leads to perturbations of core clock components and thus energy metabolism in offspring liver. Offspring from lean and obese dams were examined at post-natal day 35, following a short (2 wk HFD challenge. Hepatic mRNA expression of circadian (CLOCK, BMAL1, REV-ERBα, CRY, PER and metabolic (PPARα, SIRT1 genes were strongly suppressed in offspring exposed to both maternal obesity and HFD. Using a mathematical model, we identified two distinct biological mechanisms that modulate PPARα mRNA expression: i decreased mRNA synthesis rates; and ii increased non-specific mRNA degradation rate. Moreover, our findings demonstrate that changes in PPARα transcription were associated with epigenomic alterations in H3K4me3 and H3K27me3 histone marks near the PPARα transcription start site. Our findings indicated that offspring from obese rat dams have detrimental alternations to circadian machinery that may contribute to impaired liver metabolism in response to HFD, specifically via reduced PPAR

  2. Adverse metabolic consequences in humans of prolonged sleep restriction combined with circadian disruption.

    Science.gov (United States)

    Buxton, Orfeu M; Cain, Sean W; O'Connor, Shawn P; Porter, James H; Duffy, Jeanne F; Wang, Wei; Czeisler, Charles A; Shea, Steven A

    2012-04-11

    Epidemiological studies link short sleep duration and circadian disruption with higher risk of metabolic syndrome and diabetes. We tested the hypotheses that prolonged sleep restriction with concurrent circadian disruption, as can occur in people performing shift work, impairs glucose regulation and metabolism. Healthy adults spent >5 weeks under controlled laboratory conditions in which they experienced an initial baseline segment of optimal sleep, 3 weeks of sleep restriction (5.6 hours of sleep per 24 hours) combined with circadian disruption (recurring 28-hour "days"), followed by 9 days of recovery sleep with circadian re-entrainment. Exposure to prolonged sleep restriction with concurrent circadian disruption, with measurements taken at the same circadian phase, decreased the participants' resting metabolic rate and increased plasma glucose concentrations after a meal, an effect resulting from inadequate pancreatic insulin secretion. These parameters normalized during the 9 days of recovery sleep and stable circadian re-entrainment. Thus, in humans, prolonged sleep restriction with concurrent circadian disruption alters metabolism and could increase the risk of obesity and diabetes.

  3. The Olympic of Textile Machinery closed

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The five days 2012 China International Textile Machinery Exhibition ITMA Asia Exhibition, which attracted much attention from the industry, was closed at the Shanghai New International Expo Center on June 16, more than 1300 textile enterprises from nearly 30 countries around the world gathered on the exhibition, the world’s latest textile machinery technologies, crafts and equipments were also presented one by one.

  4. 46 CFR 115.804 - Machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Machinery. 115.804 Section 115.804 Shipping COAST GUARD....804 Machinery. At each initial and subsequent inspection for certification of a vessel, the owner or managing operator shall be prepared to conduct tests and have the vessel ready for inspections of...

  5. China Textile Machinery Expresses Self-Surpassing

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    It’s difficult to imagine that any sector of the textile industry has benefited more from innovations in the past 10 years than textile machinery. Advanced textile machinery has brought new life to the production segment of the business and fulfills the essential preconditions for economically efficient textile production.

  6. 46 CFR 58.01-40 - Machinery, angles of inclination.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Machinery, angles of inclination. 58.01-40 Section 58.01... AUXILIARY MACHINERY AND RELATED SYSTEMS General Requirements § 58.01-40 Machinery, angles of inclination. (a) Propulsion machinery and all auxiliary machinery essential to the propulsion and safety of the vessel must...

  7. 46 CFR 58.01-45 - Machinery space, ventilation.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Machinery space, ventilation. 58.01-45 Section 58.01-45... MACHINERY AND RELATED SYSTEMS General Requirements § 58.01-45 Machinery space, ventilation. Each machinery space must be ventilated to ensure that, when machinery or boilers are operating at full power in...

  8. Relationship between Human Pupillary Light Reflex and Circadian System Status

    Science.gov (United States)

    Bonmati-Carrion, Maria Angeles; Hild, Konstanze; Isherwood, Cheryl; Sweeney, Stephen J.; Revell, Victoria L.; Skene, Debra J.; Rol, Maria Angeles; Madrid, Juan Antonio

    2016-01-01

    Intrinsically photosensitive retinal ganglion cells (ipRGCs), whose photopigment melanopsin has a peak of sensitivity in the short wavelength range of the spectrum, constitute a common light input pathway to the olivary pretectal nucleus (OPN), the pupillary light reflex (PLR) regulatory centre, and to the suprachiasmatic nuclei (SCN), the major pacemaker of the circadian system. Thus, evaluating PLR under short wavelength light (λmax ≤ 500 nm) and creating an integrated PLR parameter, as a possible tool to indirectly assess the status of the circadian system, becomes of interest. Nine monochromatic, photon-matched light stimuli (300 s), in 10 nm increments from λmax 420 to 500 nm were administered to 15 healthy young participants (8 females), analyzing: i) the PLR; ii) wrist temperature (WT) and motor activity rhythms (WA), iii) light exposure (L) pattern and iv) diurnal preference (Horne-Östberg), sleep quality (Pittsburgh) and daytime sleepiness (Epworth). Linear correlations between the different PLR parameters and circadian status index obtained from WT, WA and L recordings and scores from questionnaires were calculated. In summary, we found markers of robust circadian rhythms, namely high stability, reduced fragmentation, high amplitude, phase advance and low internal desynchronization, were correlated with a reduced PLR to 460–490 nm wavelengths. Integrated circadian (CSI) and PLR (cp-PLR) parameters are proposed, that also showed an inverse correlation. These results demonstrate, for the first time, the existence of a close relationship between the circadian system robustness and the pupillary reflex response, two non-visual functions primarily under melanopsin-ipRGC input. PMID:27636197

  9. Circadian rhythms synchronize mitosis in Neurospora crassa

    OpenAIRE

    Hong, Christian I.; Zámborszky, Judit; Baek, Mokryun; Labiscsak, Laszlo; Ju, Kyungsu; Lee, Hyeyeong; Luis F. Larrondo; Goity, Alejandra; Chong, Hin Siong; Belden, William J.; Csikász-Nagy, Attila

    2014-01-01

    Circadian rhythms provide temporal information to other cellular processes, such as metabolism. We investigate the coupling between the cell cycle and the circadian clock using mathematical modeling and experimentally validate model-driven predictions with a model filamentous fungus, Neurospora crassa. We demonstrate a conserved coupling mechanism between the cell cycle and the circadian clock in Neurospora as in mammals, which results in circadian clock-gated mitotic cycles. Furthermore, we ...

  10. Circadian control of the sleep-wake cycle

    NARCIS (Netherlands)

    Beersma, Domien G. M.; Gordijn, Marijke C. M.

    2007-01-01

    It is beyond doubt that the timing of sleep is under control of the circadian pacemaker. Humans are a diurnal species; they sleep mostly at night, and they do so at approximately 24-h intervals. If they do not adhere to this general pattern, for instance when working night shifts or when travelling

  11. Nutrition and the circadian system.

    Science.gov (United States)

    Potter, Gregory D M; Cade, Janet E; Grant, Peter J; Hardie, Laura J

    2016-08-01

    The human circadian system anticipates and adapts to daily environmental changes to optimise behaviour according to time of day and temporally partitions incompatible physiological processes. At the helm of this system is a master clock in the suprachiasmatic nuclei (SCN) of the anterior hypothalamus. The SCN are primarily synchronised to the 24-h day by the light/dark cycle; however, feeding/fasting cycles are the primary time cues for clocks in peripheral tissues. Aligning feeding/fasting cycles with clock-regulated metabolic changes optimises metabolism, and studies of other animals suggest that feeding at inappropriate times disrupts circadian system organisation, and thereby contributes to adverse metabolic consequences and chronic disease development. 'High-fat diets' (HFD) produce particularly deleterious effects on circadian system organisation in rodents by blunting feeding/fasting cycles. Time-of-day-restricted feeding, where food availability is restricted to a period of several hours, offsets many adverse consequences of HFD in these animals; however, further evidence is required to assess whether the same is true in humans. Several nutritional compounds have robust effects on the circadian system. Caffeine, for example, can speed synchronisation to new time zones after jetlag. An appreciation of the circadian system has many implications for nutritional science and may ultimately help reduce the burden of chronic diseases.

  12. Circadian systems : different levels of complexity

    NARCIS (Netherlands)

    Roenneberg, Till; Merrow, Martha

    2001-01-01

    After approximately 50 years of circadian research, especially in selected circadian model systems (Drosophila, Neurospora, Gonyaulax and, more recently, cyanobacteria and mammals), we appreciate the enormous complexity of the circadian programme in organisms and cells, as well as in physiological a

  13. [Circadian rhythm in myocardial infarct].

    Science.gov (United States)

    Enciso, R; Ramos, M A; Badui, E; Hurtado, R

    1988-01-01

    In order to determine if the beginning of the Myocardial Infarction (MI) is at random along the day or if it follows a circadian rhythm, we analyzed the clinical charts of 819 patients admitted to the Coronary Care Unite. Among them, 645 were male and 174 female. It was established that the beginning of the MI follows a circadian rhythm with maximal frequency between 8 and 9 a.m. and minimal at 0 hours (p greater than 0.01). This rhythm is sex independent. In patients younger than 45 years as well as those who received beta-block agents in less than 24 hours previous the MI no circadian rhythm was observed.

  14. Stochastic noise in splicing machinery.

    Science.gov (United States)

    Melamud, Eugene; Moult, John

    2009-08-01

    The number of known alternative human isoforms has been increasing steadily with the amount of available transcription data. To date, over 100 000 isoforms have been detected in EST libraries, and at least 75% of human genes have at least one alternative isoform. In this paper, we propose that most alternative splicing events are the result of noise in the splicing process. We show that the number of isoforms and their abundance can be predicted by a simple stochastic noise model that takes into account two factors: the number of introns in a gene and the expression level of a gene. The results strongly support the hypothesis that most alternative splicing is a consequence of stochastic noise in the splicing machinery, and has no functional significance. The results are also consistent with error rates tuned to ensure that an adequate level of functional product is produced and to reduce the toxic effect of accumulation of misfolding proteins. Based on simulation of sampling of virtual cDNA libraries, we estimate that error rates range from 1 to 10% depending on the number of introns and the expression level of a gene.

  15. Effects of Gravity on Insect Circadian Rhythmicity

    Science.gov (United States)

    Hoban-Higgins, Tana M.

    2000-01-01

    Circadian rhythms - endogenous daily rhythmic fluctuations in virtually all characteristics of life - are generated and coordinated by the circadian timing system (CTS). The CTS is synchronized to the external 24-hour day by time cues such as the light/dark cycle. In an environment without time cues, the length of an animal's day is determined by the period of its internal pacemaker (tau) and the animal is said to be free-running. All life on earth evolved under the solar day; the CTS exists as an adaptation that allows organisms to anticipate and to prepare for rhythmic environmental fluctuations. All life on earth also evolved under the force of earth's gravitational environment. While it is therefore not surprising that changes in the lighting environment affect the CTS, it is surprising that changes in the gravitational environment would do so. However, recent data from one of our laboratories using the brn-3.1 knockout mouse revealed that this model, which lacks the sensory receptor hair cells within the neurovestibular system, does not respond to exposure to a hyperdynamic environment in the same fashion as normal mice. The brn-3.1 mice did not show the expected suppression of circadian rhythmicity shown by control mice exposed to 2G. Exposure to altered ambient force environments affects the amplitude, mean and timing of circadian rhythms in species from unicellular organisms to man. In addition, there is a circadian influence on the homeostatic response to acute 2G acceleration and pulses of 2G can act as a time cue, synchronizing the CTS. This is of significance because maintenance of internal and external temporal coordination is critical for normal physiological and psychological function. Typically, during adaptation to an increased gravitational environment (+G), an initial acute reaction is followed by adaptation and, eventually, a new steady state (14-16), which can take weeks to months to establish. Until the development of space stations, exposure

  16. Circadian Insights into Motivated Behavior.

    Science.gov (United States)

    Antle, Michael C; Silver, Rae

    2016-01-01

    For an organism to be successful in an evolutionary sense, it and its offspring must survive. Such survival depends on satisfying a number of needs that are driven by motivated behaviors, such as eating, sleeping, and mating. An individual can usually only pursue one motivated behavior at a time. The circadian system provides temporal structure to the organism's 24 hour day, partitioning specific behaviors to particular times of the day. The circadian system also allows anticipation of opportunities to engage in motivated behaviors that occur at predictable times of the day. Such anticipation enhances fitness by ensuring that the organism is physiologically ready to make use of a time-limited resource as soon as it becomes available. This could include activation of the sympathetic nervous system to transition from sleep to wake, or to engage in mating, or to activate of the parasympathetic nervous system to facilitate transitions to sleep, or to prepare the body to digest a meal. In addition to enabling temporal partitioning of motivated behaviors, the circadian system may also regulate the amplitude of the drive state motivating the behavior. For example, the circadian clock modulates not only when it is time to eat, but also how hungry we are. In this chapter we explore the physiology of our circadian clock and its involvement in a number of motivated behaviors such as sleeping, eating, exercise, sexual behavior, and maternal behavior. We also examine ways in which dysfunction of circadian timing can contribute to disease states, particularly in psychiatric conditions that include adherent motivational states.

  17. A Long Noncoding RNA Perturbs the Circadian Rhythm of Hepatoma Cells to Facilitate Hepatocarcinogenesis

    Directory of Open Access Journals (Sweden)

    Ming Cui

    2015-01-01

    Full Text Available Clock circadian regulator (CLOCK/brain and muscle arnt-like protein-1 (BMAL1 complex governs the regulation of circadian rhythm through triggering periodic alterations of gene expression. However, the underlying mechanism of circadian clock disruption in hepatocellular carcinoma (HCC remains unclear. Here, we report that a long noncoding RNA (lncRNA, highly upregulated in liver cancer (HULC, contributes to the perturbations in circadian rhythm of hepatoma cells. Our observations showed that HULC was able to heighten the expression levels of CLOCK and its downstream circadian oscillators, such as period circadian clock 1 and cryptochrome circadian clock 1, in hepatoma cells. Strikingly, HULC altered the expression pattern and prolonged the periodic expression of CLOCK in hepatoma cells. Mechanistically, the complementary base pairing between HULC and the 5' untranslated region of CLOCK mRNA underlay the HULC-modulated expression of CLOCK, and the mutants in the complementary region failed to achieve the event. Moreover, immunohistochemistry staining and quantitative real-time polymerase chain reaction validated that the levels of CLOCK were elevated in HCC tissues, and the expression levels of HULC were positively associated with those of CLOCK in clinical HCC samples. In functional experiments, our data exhibited that CLOCK was implicated in the HULC-accelerated proliferation of hepatoma cells in vitro and in vivo. Taken together, our data show that an lncRNA, HULC, is responsible for the perturbations in circadian rhythm through upregulating circadian oscillator CLOCK in hepatoma cells, resulting in the promotion of hepatocarcinogenesis. Thus, our finding provides new insights into the mechanism by which lncRNA accelerates hepatocarcinogenesis through disturbing circadian rhythm of HCC.

  18. Later endogenous circadian temperature nadir relative to an earlier wake time in older people

    Science.gov (United States)

    Duffy, J. F.; Dijk, D. J.; Klerman, E. B.; Czeisler, C. A.

    1998-01-01

    The contribution of the circadian timing system to the age-related advance of sleep-wake timing was investigated in two experiments. In a constant routine protocol, we found that the average wake time and endogenous circadian phase of 44 older subjects were earlier than that of 101 young men. However, the earlier circadian phase of the older subjects actually occurred later relative to their habitual wake time than it did in young men. These results indicate that an age-related advance of circadian phase cannot fully account for the high prevalence of early morning awakening in healthy older people. In a second study, 13 older subjects and 10 young men were scheduled to a 28-h day, such that they were scheduled to sleep at many circadian phases. Self-reported awakening from scheduled sleep episodes and cognitive throughput during the second half of the wake episode varied markedly as a function of circadian phase in both groups. The rising phase of both rhythms was advanced in the older subjects, suggesting an age-related change in the circadian regulation of sleep-wake propensity. We hypothesize that under entrained conditions, these age-related changes in the relationship between circadian phase and wake time are likely associated with self-selected light exposure at an earlier circadian phase. This earlier exposure to light could account for the earlier clock hour to which the endogenous circadian pacemaker is entrained in older people and thereby further increase their propensity to awaken at an even earlier time.

  19. Circadian regulation of glutathione levels and biosynthesis in Drosophila melanogaster.

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    Laura M Beaver

    Full Text Available Circadian clocks generate daily rhythms in neuronal, physiological, and metabolic functions. Previous studies in mammals reported daily fluctuations in levels of the major endogenous antioxidant, glutathione (GSH, but the molecular mechanisms that govern such fluctuations remained unknown. To address this question, we used the model species Drosophila, which has a rich arsenal of genetic tools. Previously, we showed that loss of the circadian clock increased oxidative damage and caused neurodegenerative changes in the brain, while enhanced GSH production in neuronal tissue conferred beneficial effects on fly survivorship under normal and stress conditions. In the current study we report that the GSH concentrations in fly heads fluctuate in a circadian clock-dependent manner. We further demonstrate a rhythm in activity of glutamate cysteine ligase (GCL, the rate-limiting enzyme in glutathione biosynthesis. Significant rhythms were also observed for mRNA levels of genes encoding the catalytic (Gclc and modulatory (Gclm subunits comprising the GCL holoenzyme. Furthermore, we found that the expression of a glutathione S-transferase, GstD1, which utilizes GSH in cellular detoxification, significantly fluctuated during the circadian day. To directly address the role of the clock in regulating GSH-related rhythms, the expression levels of the GCL subunits and GstD1, as well as GCL activity and GSH production were evaluated in flies with a null mutation in the clock genes cycle and period. The rhythms observed in control flies were not evident in the clock mutants, thus linking glutathione production and utilization to the circadian system. Together, these data suggest that the circadian system modulates pathways involved in production and utilization of glutathione.

  20. Metabolic Cycles in Yeast Share Features Conserved among Circadian Rhythms.

    Science.gov (United States)

    Causton, Helen C; Feeney, Kevin A; Ziegler, Christine A; O'Neill, John S

    2015-04-20

    Cell-autonomous circadian rhythms allow organisms to temporally orchestrate their internal state to anticipate and/or resonate with the external environment. Although ∼24-hr periodicity is observed across aerobic eukaryotes, the central mechanism has been hard to dissect because few simple models exist, and known clock proteins are not conserved across phylogenetic kingdoms. In contrast, contributions to circadian rhythmicity made by a handful of post-translational mechanisms, such as phosphorylation of clock proteins by casein kinase 1 (CK1) and glycogen synthase kinase 3 (GSK3), appear conserved among phyla. These kinases have many other essential cellular functions and are better conserved in their contribution to timekeeping than any of the clock proteins they phosphorylate. Rhythmic oscillations in cellular redox state are another universal feature of circadian timekeeping, e.g., over-oxidation cycles of abundant peroxiredoxin proteins. Here, we use comparative chronobiology to distinguish fundamental clock mechanisms from species and/or tissue-specific adaptations and thereby identify features shared between circadian rhythms in mammalian cells and non-circadian temperature-compensated respiratory oscillations in budding yeast. We find that both types of oscillations are coupled with the cell division cycle, exhibit period determination by CK1 and GSK3, and have peroxiredoxin over-oxidation cycles. We also explore how peroxiredoxins contribute to YROs. Our data point to common mechanisms underlying both YROs and circadian rhythms and suggest two interpretations: either certain biochemical systems are simply permissive for cellular oscillations (with frequencies from hours to days) or this commonality arose via divergence from an ancestral cellular clock.

  1. Dysglycemia induces abnormal circadian blood pressure variability

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    Kumarasamy Sivarajan

    2011-11-01

    Full Text Available Abstract Background Prediabetes (PreDM in asymptomatic adults is associated with abnormal circadian blood pressure variability (abnormal CBPV. Hypothesis Systemic inflammation and glycemia influence circadian blood pressure variability. Methods Dahl salt-sensitive (S rats (n = 19 after weaning were fed either an American (AD or a standard (SD diet. The AD (high-glycemic-index, high-fat simulated customary human diet, provided daily overabundant calories which over time lead to body weight gain. The SD (low-glycemic-index, low-fat mirrored desirable balanced human diet for maintaining body weight. Body weight and serum concentrations for fasting glucose (FG, adipokines (leptin and adiponectin, and proinflammatory cytokines [monocyte chemoattractant protein-1 (MCP-1 and tumor necrosis factor-α (TNF-α] were measured. Rats were surgically implanted with C40 transmitters and blood pressure (BP-both systolic; SBP and diastolic; DBP and heart rate (HR were recorded by telemetry every 5 minutes during both sleep (day and active (night periods. Pulse pressure (PP was calculated (PP = SBP-DBP. Results [mean(SEM]: The AD fed group displayed significant increase in body weight (after 90 days; p Conclusion These data validate our stated hypothesis that systemic inflammation and glycemia influence circadian blood pressure variability. This study, for the first time, demonstrates a cause and effect relationship between caloric excess, enhanced systemic inflammation, dysglycemia, loss of blood pressure control and abnormal CBPV. Our results provide the fundamental basis for examining the relationship between dysglycemia and perturbation of the underlying mechanisms (adipose tissue dysfunction induced local and systemic inflammation, insulin resistance and alteration of adipose tissue precursors for the renin-aldosterone-angiotensin system which generate abnormal CBPV.

  2. Evolution of circadian rhythms in Drosophila melanogaster populations reared in constant light and dark regimes for over 330 generations.

    Science.gov (United States)

    Shindey, Radhika; Varma, Vishwanath; Nikhil, K L; Sharma, Vijay Kumar

    2017-02-03

    Organisms are believed to have evolved circadian clocks as adaptations to deal with cyclic environmental changes, and therefore it has been hypothesized that evolution in constant environments would lead to regression of such clocks. However, previous studies have yielded mixed results, and evolution of circadian clocks under constant conditions has remained an unsettled topic of debate in circadian biology. In continuation of our previous studies, which reported persistence of circadian rhythms in Drosophila melanogaster populations evolving under constant light, here we intended to examine whether circadian clocks and the associated properties evolve differently under constant light and constant darkness. In this regard, we assayed activity-rest, adult emergence and oviposition rhythms of D. melanogaster populations which have been maintained for over 19 years (~330 generations) under three different light regimes - constant light (LL), light-dark cycles of 12:12 h (LD) and constant darkness (DD). We observed that while circadian rhythms in all the three behaviors persist in both LL and DD stocks with no differences in circadian period, they differed in certain aspects of the entrained rhythms when compared to controls reared in rhythmic environment (LD). Interestingly, we also observed that DD stocks have evolved significantly higher robustness or power of free-running activity-rest and adult emergence rhythms compared to LL stocks. Thus, our study, in addition to corroborating previous results of circadian clock evolution in constant light, also highlights that, contrary to the expected regression of circadian clocks, rearing in constant darkness leads to the evolution of more robust circadian clocks which may be attributed to an intrinsic adaptive advantage of circadian clocks and/or pleiotropic functions of clock genes in other traits.

  3. Genome-wide analysis of light- and temperature-entrained circadian transcripts in Caenorhabditis elegans.

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    Alexander M van der Linden

    Full Text Available Most organisms have an endogenous circadian clock that is synchronized to environmental signals such as light and temperature. Although circadian rhythms have been described in the nematode Caenorhabditis elegans at the behavioral level, these rhythms appear to be relatively non-robust. Moreover, in contrast to other animal models, no circadian transcriptional rhythms have been identified. Thus, whether this organism contains a bona fide circadian clock remains an open question. Here we use genome-wide expression profiling experiments to identify light- and temperature-entrained oscillating transcripts in C. elegans. These transcripts exhibit rhythmic expression with temperature-compensated 24-h periods. In addition, their expression is sustained under constant conditions, suggesting that they are under circadian regulation. Light and temperature cycles strongly drive gene expression and appear to entrain largely nonoverlapping gene sets. We show that mutations in a cyclic nucleotide-gated channel required for sensory transduction abolish both light- and temperature-entrained gene expression, implying that environmental cues act cell nonautonomously to entrain circadian rhythms. Together, these findings demonstrate circadian-regulated transcriptional rhythms in C. elegans and suggest that further analyses in this organism will provide new information about the evolution and function of this biological clock.

  4. Mammalian TIMELESS Is Involved in Period Determination and DNA Damage-Dependent Phase Advancing of the Circadian Clock

    NARCIS (Netherlands)

    M.P. Engelen (Erik); R. Janssens (Roel); K. Yagita (Kazuhiro); V.A.J. Smits (Veronique); G.T.J. van der Horst (Gijsbertus); F. Tamanini (Filippo)

    2013-01-01

    textabstractThe transcription/translation feedback loop-based molecular oscillator underlying the generation of circadian gene expression is preserved in almost all organisms. Interestingly, the animal circadian clock proteins CRYPTOCHROME (CRY), PERIOD (PER) and TIMELESS (TIM) are strongly conserve

  5. The flexible clock : Predictive and reactive homeostasis, energy balance and the circadian regulation of sleep-wake timing

    NARCIS (Netherlands)

    Riede, Sjaak J.; van der Vinne, Vincent; Hut, Roelof A.

    2017-01-01

    The Darwinian fitness of mammals living in a rhythmic environment depends on endogenous daily (circadian) rhythms in behavior and physiology. Here, we discuss the mechanisms underlying the circadian regulation of physiology and behavior in mammals. We also review recent efforts to understand

  6. The alteration of human sleep and circadian rhythms during spaceflight.

    Science.gov (United States)

    Gundel, A; Polyakov, V V; Zulley, J

    1997-03-01

    Numerous anecdotes in the past suggest the concept that sleep disturbances in astronauts occur more frequently during spaceflight than on ground. Such disturbances may be caused in part by exogenous factors, but also an altered physiological state under microgravity may add to reducing sleep quality in a spacecraft. The present investigation aims at a better understanding of possible sleep disturbances under microgravity. For the first time, experiments were conducted in which sleep and circadian regulation could be simultaneously assessed in space. Four astronauts took part in this study aboard the Russian MIR station. Sleep was recorded polygraphically on tape together with body temperature. For a comparison, the same parameters were measured during baseline periods preceding the flights. The circadian phase of body temperature was found to be delayed by about 2 h in space compared with baseline data. A free-run was not observed during the first 30 d in space. Sleep was shorter and more disturbed than on earth. In addition, the structure of sleep was significantly altered. In space, the latency to the first REM episode was shorter, and slow-wave sleep was redistributed from the first to the second sleep cycle. Several mechanisms may be responsible for these alterations in sleep regulation and circadian phase. Most likely, altered circadian zeitgebers on MIR and a deficiency in the process S of Borbély's sleep model cause the observed findings. The change in process S may be related to changes in physical activity as a result of weightlessness.

  7. The circadian clock regulates auxin signaling and responses in Arabidopsis.

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    Michael F Covington

    2007-08-01

    Full Text Available The circadian clock plays a pervasive role in the temporal regulation of plant physiology, environmental responsiveness, and development. In contrast, the phytohormone auxin plays a similarly far-reaching role in the spatial regulation of plant growth and development. Went and Thimann noted 70 years ago that plant sensitivity to auxin varied according to the time of day, an observation that they could not explain. Here we present work that explains this puzzle, demonstrating that the circadian clock regulates auxin signal transduction. Using genome-wide transcriptional profiling, we found many auxin-induced genes are under clock regulation. We verified that endogenous auxin signaling is clock regulated with a luciferase-based assay. Exogenous auxin has only modest effects on the plant clock, but the clock controls plant sensitivity to applied auxin. Notably, we found both transcriptional and growth responses to exogenous auxin are gated by the clock. Thus the circadian clock regulates some, and perhaps all, auxin responses. Consequently, many aspects of plant physiology not previously thought to be under circadian control may show time-of-day-specific sensitivity, with likely important consequences for plant growth and environmental responses.

  8. Circadian remodeling of neuronal circuits involved in rhythmic behavior.

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    María Paz Fernández

    2008-03-01

    Full Text Available Clock output pathways are central to convey timing information from the circadian clock to a diversity of physiological systems, ranging from cell-autonomous processes to behavior. While the molecular mechanisms that generate and sustain rhythmicity at the cellular level are well understood, it is unclear how this information is further structured to control specific behavioral outputs. Rhythmic release of pigment dispersing factor (PDF has been proposed to propagate the time of day information from core pacemaker cells to downstream targets underlying rhythmic locomotor activity. Indeed, such circadian changes in PDF intensity represent the only known mechanism through which the PDF circuit could communicate with its output. Here we describe a novel circadian phenomenon involving extensive remodeling in the axonal terminals of the PDF circuit, which display higher complexity during the day and significantly lower complexity at nighttime, both under daily cycles and constant conditions. In support to its circadian nature, cycling is lost in bona fide clockless mutants. We propose this clock-controlled structural plasticity as a candidate mechanism contributing to the transmission of the information downstream of pacemaker cells.

  9. Synchronization of the Drosophila circadian clock by temperature cycles.

    Science.gov (United States)

    Glaser, F T; Stanewsky, R

    2007-01-01

    The natural light/dark and temperature cycles are considered to be the most prominent factors that synchronize circadian clocks with the environment. Understanding the principles of temperature entrainment significantly lags behind our current knowledge of light entrainment in any organism subject to circadian research. Nevertheless, several effects of temperature on circadian clocks are well understood, and similarities as well as differences to the light-entrainment pathways start to emerge. This chapter provides an overview of the temperature effects on the Drosophila circadian clock with special emphasis on synchronization by temperature cycles. As in other organisms, such temperature cycles can serve as powerful time cues to synchronize the clock. Mutants that specifically interfere with aspects of temperature entrainment have been isolated and will likely help to reveal the underlying mechanisms. These mechanisms involve transcriptional and posttranscriptional regulation of clock genes. For synchronization of fly behavior by temperature cycles, the generation of a whole organism or systemic signal seems to be required, even though individual fly tissues can be synchronized under isolated culture conditions. If true, the requirement for such a signal would reveal a fundamental difference to the light-entrainment mechanism.

  10. Early development of circadian rhythmicity in the suprachiamatic nuclei and pineal gland of teleost, flounder (Paralichthys olivaeus), embryos.

    Science.gov (United States)

    Mogi, Makoto; Uji, Susumu; Yokoi, Hayato; Suzuki, Tohru

    2015-08-01

    Circadian rhythms enable organisms to coordinate multiple physiological processes and behaviors with the earth's rotation. In mammals, the suprachiasmatic nuclei (SCN), the sole master circadian pacemaker, has entrainment mechanisms that set the circadian rhythm to a 24-h cycle with photic signals from retina. In contrast, the zebrafish SCN is not a circadian pacemaker, instead the pineal gland (PG) houses the major circadian oscillator. The SCN of flounder larvae, unlike that of zebrafish, however, expresses per2 with a rhythmicity of daytime/ON and nighttime/OFF. Here, we examined whether the rhythm of per2 expression in the flounder SCN represents the molecular clock. We also examined early development of the circadian rhythmicity in the SCN and PG. Our three major findings were as follows. First, rhythmic per2 expression in the SCN was maintained under 24 h dark (DD) conditions, indicating that a molecular clock exists in the flounder SCN. Second, onset of circadian rhythmicity in the SCN preceded that in the PG. Third, both 24 h light (LL) and DD conditions deeply affected the development of circadian rhythmicity in the SCN and PG. This is the first report dealing with the early development of circadian rhythmicity in the SCN in fish.

  11. Textile Machinery:Imports Rebound Again

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In the year of 2006,the general situation of China’s textile machinery equipment imports had shown a clear sign of revival from the downward trend of two years ago,with a total annual import of 4.1 billion USD,an increase of 19.05% against the same period of 2005. Continuingly,the year of 2007 has witnessed a sustainable growth trend of textile machinery equipment imports in the first quarter and the trend definitely will be maintained through the whole year.According to statistics released from China Customs,the imports of textile machinery reached 1.098 billion USD in the first three months of 2007, up by 35.26% year-on-year. Then,why China’s textile machinery imports warm up again after two years’ cool down?

  12. A comprehensive overview of hybrid construction machinery

    Directory of Open Access Journals (Sweden)

    Jixin Wang

    2016-03-01

    Full Text Available With the increasing attention of energy saving and emission reduction technology, the recent application of hybrid powertrain technology affects the development of construction machinery industry. This article reviews these publications and provides comprehensive references. This article reviews the state-of-art for the hybrid wheel loader and excavator, which focuses on powertrain configuration, energy storage devices, and energy management strategies. The basis of classification and characteristic of each powertrain configuration are described. Advantages and disadvantages of batteries, supercapacitors, hydraulic accumulators, and flywheel used in hybrid construction machinery are summarized. The existing energy management strategies for hybrid construction machinery are also elaborated. The technological challenges and developing trends in the near future for hybrid construction machinery are discussed.

  13. Energy Savings Thanks to French Textile Machinery

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The French Textile Machinery Manufacturers’ Association (UCMTF) has presented,during a seminar it organized for textile professionals and students,the spectacular energy savings achieved thanks to state of the art

  14. ADHD, circadian rhythms and seasonality

    NARCIS (Netherlands)

    Wynchank, Dora S.; Bijlenga, Denise; Lamers, Femke; Bron, Tannetje I.; Winthorst, Wim H.; Vogel, Suzan W.; Penninx, Brenda W.; Beekman, Aartjan T.; Kooij, J. Sandra

    2016-01-01

    Objective: We evaluated whether the association between Adult Attention-Deficit/Hyperactivity Disorder (ADHD) and Seasonal Affective Disorder (SAD) was mediated by the circadian rhythm. Method: Data of 2239 persons from the Netherlands Study of Depression and Anxiety (NESDA) were used. Two groups we

  15. ADHD, circadian rhythms and seasonality

    NARCIS (Netherlands)

    Wynchank, Dora S.; Bijlenga, Denise; Lamers, Femke; Bron, Tannetje I.; Winthorst, Wim H.; Vogel, Suzan W.; Penninx, Brenda W.; Beekman, Aartjan T.; Kooij, J. Sandra

    2016-01-01

    Objective: We evaluated whether the association between Adult Attention-Deficit/Hyperactivity Disorder (ADHD) and Seasonal Affective Disorder (SAD) was mediated by the circadian rhythm. Method: Data of 2239 persons from the Netherlands Study of Depression and Anxiety (NESDA) were used. Two groups we

  16. ADHD, circadian rhythms and seasonality

    NARCIS (Netherlands)

    Wynchank, Dora S.; Bijlenga, Denise; Lamers, Femke; Bron, Tannetje I.; Winthorst, Wim H.; Vogel, Suzan W.; Penninx, Brenda W.; Beekman, Aartjan T.; Kooij, J. Sandra

    2016-01-01

    Objective: We evaluated whether the association between Adult Attention-Deficit/Hyperactivity Disorder (ADHD) and Seasonal Affective Disorder (SAD) was mediated by the circadian rhythm. Method: Data of 2239 persons from the Netherlands Study of Depression and Anxiety (NESDA) were used. Two groups

  17. Textile Machinery Import and Export in 2011

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Along with the rebounded international market, in the year of 2011, the foreign trade of textile machinery industry preserved a stable development: the import amount saw a slightly decrease, while the total import and export value kept an increasing trend. According to the Customs, the export and import of textile machinery totalized 2.245 billion USD and 5.364 billion USD, increasing by 27.81% and 24.70%, respectively, comparing with the same period of time in 2010.

  18. Phosphoproteome Profiling Reveals Circadian Clock Regulation of Posttranslational Modifications in the Murine Hippocampus

    Science.gov (United States)

    Chiang, Cheng-Kang; Xu, Bo; Mehta, Neel; Mayne, Janice; Sun, Warren Y. L.; Cheng, Kai; Ning, Zhibin; Dong, Jing; Zou, Hanfa; Cheng, Hai-Ying Mary; Figeys, Daniel

    2017-01-01

    The circadian clock is an endogenous oscillator that drives daily rhythms in physiology, behavior, and gene expression. The underlying mechanisms of circadian timekeeping are cell-autonomous and involve oscillatory expression of core clock genes that is driven by interconnecting transcription–translation feedback loops (TTFLs). Circadian clock TTFLs are further regulated by posttranslational modifications, in particular, phosphorylation. The hippocampus plays an important role in spatial memory and the conversion of short- to long-term memory. Several studies have reported the presence of a peripheral oscillator in the hippocampus and have highlighted the importance of circadian regulation in memory formation. Given the general importance of phosphorylation in circadian clock regulation, we performed global quantitative proteome and phosphoproteome analyses of the murine hippocampus across the circadian cycle, applying spiked-in labeled reference and high accuracy mass spectrometry (MS). Of the 3,052 proteins and 2,868 phosphosites on 1,368 proteins that were accurately quantified, 1.7% of proteins and 5.2% of phosphorylation events exhibited time-of-day-dependent expression profiles. The majority of circadian phosphopeptides displayed abrupt fluctuations at mid-to-late day without underlying rhythms of protein abundance. Bioinformatic analysis of cyclic phosphorylation events revealed their diverse distribution in different biological pathways, most notably, cytoskeletal organization and neuronal morphogenesis. This study provides the first large-scale, quantitative MS analysis of the circadian phosphoproteome and proteome of the murine hippocampus and highlights the significance of rhythmic regulation at the posttranslational level in this peripheral oscillator. In addition to providing molecular insights into the hippocampal circadian clock, our results will assist in the understanding of genetic factors that underlie rhythms-associated pathological states of

  19. Drugs of Abuse Can Entrain Circadian Rhythms

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    Ann E. K. Kosobud

    2007-01-01

    Full Text Available Circadian rhythms prepare organisms for predictable events during the Earth's 24-h day. These rhythms are entrained by a variety of stimuli. Light is the most ubiquitous and best known zeitgeber, but a number of others have been identified, including food, social cues, locomotor activity, and, most recently drugs of abuse. Given the diversity of zeitgebers, it is probably not surprising that genes capable of clock functions are located throughout almost all organs and tissues. Recent evidence suggests that drugs of abuse can directly entrain some circadian rhythms. We have report here that entrainment by drugs of abuse is independent of the suprachiasmatic nucleus and the light/dark cycle, is not dependent on direct locomotor stimulation, and is shared by a variety of classes of drugs of abuse. We suggest that drug-entrained rhythms reflect variations in underlying neurophysiological states. This could be the basis for known daily variations in drug metabolism, tolerance, and sensitivity to drug reward. These rhythms could also take the form of daily periods of increased motivation to seek and take drugs, and thus contribute to abuse, addiction and relapse.

  20. Drugs of abuse can entrain circadian rhythms.

    Science.gov (United States)

    Kosobud, Ann E K; Gillman, Andrea G; Leffel, Joseph K; Pecoraro, Norman C; Rebec, G V; Timberlake, William

    2007-11-02

    Circadian rhythms prepare organisms for predictable events in the 24 h day. These rhythms are entrained by a variety of stimuli. Light is the most ubiquitous and best known zeitgeber, but a number of others have been identified, including food, social cues, locomotor activity, and, most recently drugs of abuse. Given the diversity of zeitgebers, it is probably not surprising that genes capable of clock functions are located throughout almost all organs and tissues. Recent evidence suggests that drugs of abuse can directly entrain some circadian rhythms. We have report here that entrainment by drugs of abuse is independent of the suprachiasmatic nucleus and the light/dark cycle, is not dependent on direct locomotor stimulation, and is shared by a variety of classes of drugs of abuse. We suggest that drug-entrained rhythms reflect variations in underlying neurophysiological states. This could be the basis for known daily variations in drug metabolism, tolerance, and sensitivity to drug reward. These rhythms could also take the form of daily periods of increased motivation to seek and take drugs, and thus contribute to abuse, addiction and relapse.

  1. Protein phosphatase-dependent circadian regulation of intermediate-term associative memory.

    Science.gov (United States)

    Michel, Maximilian; Gardner, Jacob S; Green, Charity L; Organ, Chelsea L; Lyons, Lisa C

    2013-03-01

    The endogenous circadian clock is a principal factor modulating memory across species. Determining the processes through which the circadian clock modulates memory formation is a key issue in understanding and identifying mechanisms to improve memory. We used the marine mollusk Aplysia californica to investigate circadian modulation of intermediate-term memory (ITM) and the mechanisms through which the circadian clock phase specifically suppresses memory using the operant learning paradigm, learning that food is inedible. We found that ITM, a temporally and mechanistically distinct form of memory, is rhythmically expressed under light-dark and constant conditions when induced by either massed or spaced training. Strong circadian regulation of ITM occurs with memory exhibited only by animals trained during the early subjective day; no apparent memory is expressed when training occurs during the late subjective day or night. Given the necessity of multiple persistent kinase cascades for ITM, we investigated whether protein phosphatase activity affected circadian modulation. Inhibition of protein phosphatases 1 and 2A blocked ITM when animals were trained during the early (subjective) day while resulting in phase-specific memory rescue when animals were trained late in the subjective day and early night. In contrast, inhibition of calcineurin did not block ITM when animals were trained during the early day and permitted ITM when animals were trained during the late subjective day, early evening, and throughout the night. These results demonstrate that levels of protein phosphatase activity are critical regulators of ITM and one mechanism through which the circadian clock regulates memory formation.

  2. Kernel Architecture of the Genetic Circuitry of the Arabidopsis Circadian System.

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    Mathias Foo

    2016-02-01

    Full Text Available A wide range of organisms features molecular machines, circadian clocks, which generate endogenous oscillations with ~24 h periodicity and thereby synchronize biological processes to diurnal environmental fluctuations. Recently, it has become clear that plants harbor more complex gene regulatory circuits within the core circadian clocks than other organisms, inspiring a fundamental question: are all these regulatory interactions between clock genes equally crucial for the establishment and maintenance of circadian rhythms? Our mechanistic simulation for Arabidopsis thaliana demonstrates that at least half of the total regulatory interactions must be present to express the circadian molecular profiles observed in wild-type plants. A set of those essential interactions is called herein a kernel of the circadian system. The kernel structure unbiasedly reveals four interlocked negative feedback loops contributing to circadian rhythms, and three feedback loops among them drive the autonomous oscillation itself. Strikingly, the kernel structure, as well as the whole clock circuitry, is overwhelmingly composed of inhibitory, rather than activating, interactions between genes. We found that this tendency underlies plant circadian molecular profiles which often exhibit sharply-shaped, cuspidate waveforms. Through the generation of these cuspidate profiles, inhibitory interactions may facilitate the global coordination of temporally-distant clock events that are markedly peaked at very specific times of day. Our systematic approach resulting in experimentally-testable predictions provides insights into a design principle of biological clockwork, with implications for synthetic biology.

  3. The circadian clock mutation alters sleep homeostasis in the mouse.

    Science.gov (United States)

    Naylor, E; Bergmann, B M; Krauski, K; Zee, P C; Takahashi, J S; Vitaterna, M H; Turek, F W

    2000-11-01

    The onset and duration of sleep are thought to be primarily under the control of a homeostatic mechanism affected by previous periods of wake and sleep and a circadian timing mechanism that partitions wake and sleep into different portions of the day and night. The mouse Clock mutation induces pronounced changes in overall circadian organization. We sought to determine whether this genetic disruption of circadian timing would affect sleep homeostasis. The Clock mutation affected a number of sleep parameters during entrainment to a 12 hr light/dark (LD 12:12) cycle, when animals were free-running in constant darkness (DD), and during recovery from 6 hr of sleep deprivation in LD 12:12. In particular, in LD 12:12, heterozygous and homozygous Clock mutants slept, respectively, approximately 1 and approximately 2 hr less than wild-type mice, and they had 25 and 51% smaller increases in rapid eye movement (REM) sleep during 24 hr recovery, respectively, than wild-type mice. The effects of the mutation on sleep are not readily attributable to differential entrainment to LD 12:12 because the baseline sleep differences between genotypes were also present when animals were free-running in DD. These results indicate that genetic alterations of the circadian clock system and/or its regulatory genes are likely to have widespread effects on a variety of sleep and wake parameters, including the homeostatic regulation of sleep.

  4. The role of the circadian system in fractal neurophysiological control.

    Science.gov (United States)

    Pittman-Polletta, Benjamin R; Scheer, Frank A J L; Butler, Matthew P; Shea, Steven A; Hu, Kun

    2013-11-01

    Many neurophysiological variables such as heart rate, motor activity, and neural activity are known to exhibit intrinsic fractal fluctuations - similar temporal fluctuation patterns at different time scales. These fractal patterns contain information about health, as many pathological conditions are accompanied by their alteration or absence. In physical systems, such fluctuations are characteristic of critical states on the border between randomness and order, frequently arising from nonlinear feedback interactions between mechanisms operating on multiple scales. Thus, the existence of fractal fluctuations in physiology challenges traditional conceptions of health and disease, suggesting that high levels of integrity and adaptability are marked by complex variability, not constancy, and are properties of a neurophysiological network, not individual components. Despite the subject's theoretical and clinical interest, the neurophysiological mechanisms underlying fractal regulation remain largely unknown. The recent discovery that the circadian pacemaker (suprachiasmatic nucleus) plays a crucial role in generating fractal patterns in motor activity and heart rate sheds an entirely new light on both fractal control networks and the function of this master circadian clock, and builds a bridge between the fields of circadian biology and fractal physiology. In this review, we sketch the emerging picture of the developing interdisciplinary field of fractal neurophysiology by examining the circadian system's role in fractal regulation.

  5. Circadian Rhythm Shapes the Gut Microbiota Affecting Host Radiosensitivity.

    Science.gov (United States)

    Cui, Ming; Xiao, Huiwen; Luo, Dan; Zhang, Xin; Zhao, Shuyi; Zheng, Qisheng; Li, Yuan; Zhao, Yu; Dong, Jiali; Li, Hang; Wang, Haichao; Fan, Saijun

    2016-10-26

    Modern lifestyles, such as shift work, nocturnal social activities, and jet lag, disturb the circadian rhythm. The interaction between mammals and the co-evolved intestinal microbiota modulates host physiopathological processes. Radiotherapy is a cornerstone of modern management of malignancies; however, it was previously unknown whether circadian rhythm disorder impairs prognosis after radiotherapy. To investigate the effect of circadian rhythm on radiotherapy, C57BL/6 mice were housed in different dark/light cycles, and their intestinal bacterial compositions were compared using high throughput sequencing. The survival rate, body weight, and food intake of mice in diverse cohorts were measured following irradiation exposure. Finally, the enteric bacterial composition of irradiated mice that experienced different dark/light cycles was assessed using 16S RNA sequencing. Intriguingly, mice housed in aberrant light cycles harbored a reduction of observed intestinal bacterial species and shifts of gut bacterial composition compared with those of the mice kept under 12 h dark/12 h light cycles, resulting in a decrease of host radioresistance. Moreover, the alteration of enteric bacterial composition of mice in different groups was dissimilar. Our findings provide novel insights into the effects of biological clocks on the gut bacterial composition, and underpin that the circadian rhythm influences the prognosis of patients after radiotherapy in a preclinical setting.

  6. Noise Induces Oscillation and Synchronization of the Circadian Neurons.

    Directory of Open Access Journals (Sweden)

    Changgui Gu

    Full Text Available The principle clock of mammals, named suprachiasmatic nucleus (SCN, coordinates the circadian rhythms of behavioral and physiological activity to the external 24 h light-dark cycle. In the absence of the daily cycle, the SCN acts as an endogenous clock that regulates the ~24 h rhythm of activity. Experimental and theoretical studies usually take the light-dark cycle as a main external influence, and often ignore light pollution as an external influence. However, in modern society, the light pollution such as induced by electrical lighting influences the circadian clock. In the present study, we examined the effect of external noise (light pollution on the collective behavior of coupled circadian oscillators under constant darkness using a Goodwin model. We found that the external noise plays distinct roles in the network behavior of neurons for weak or strong coupling between the neurons. In the case of strong coupling, the noise reduces the synchronization and the period of the SCN network. Interestingly, in the case of weak coupling, the noise induces a circadian rhythm in the SCN network which is absent in noise-free condition. In addition, the noise increases the synchronization and decreases the period of the SCN network. Our findings may shed new light on the impact of the external noise on the collective behavior of SCN neurons.

  7. 46 CFR 58.20-15 - Installation of refrigerating machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Installation of refrigerating machinery. 58.20-15... AND AUXILIARY MACHINERY AND RELATED SYSTEMS Refrigeration Machinery § 58.20-15 Installation of refrigerating machinery. (a) Where refrigerating machines are installed in which anhydrous ammonia is used as...

  8. 46 CFR 169.625 - Compartments containing diesel machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Compartments containing diesel machinery. 169.625... SCHOOL VESSELS Machinery and Electrical Ventilation § 169.625 Compartments containing diesel machinery. (a) Spaces containing machinery must be fitted with adequate dripproof ventilators, trunks,...

  9. 46 CFR 174.195 - Bulkheads in machinery spaces.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Bulkheads in machinery spaces. 174.195 Section 174.195... in machinery spaces. (a) The bulkhead in each machinery space of each OSV must be watertight to the bulkhead deck. (b) Each penetration of, and each opening in, a bulkhead in a machinery space must— (1)...

  10. 46 CFR 58.01-35 - Main propulsion auxiliary machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Main propulsion auxiliary machinery. 58.01-35 Section 58... AUXILIARY MACHINERY AND RELATED SYSTEMS General Requirements § 58.01-35 Main propulsion auxiliary machinery. Auxiliary machinery vital to the main propulsion system must be provided in duplicate unless the...

  11. 46 CFR 58.01-25 - Means of stopping machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Means of stopping machinery. 58.01-25 Section 58.01-25 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN AND AUXILIARY MACHINERY AND RELATED SYSTEMS General Requirements § 58.01-25 Means of stopping machinery. Machinery...

  12. 46 CFR 42.15-35 - Machinery space openings.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Machinery space openings. 42.15-35 Section 42.15-35... BY SEA Conditions of Assignment of Freeboard § 42.15-35 Machinery space openings. (a) Machinery space..., funnel, or machinery space ventilators in an exposed position on the freeboard or superstructure...

  13. 46 CFR 45.149 - Machinery space openings.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Machinery space openings. 45.149 Section 45.149 Shipping... Assignment § 45.149 Machinery space openings. (a) Machinery space openings in position 1 or 2 must be framed... funnel or machinery space ventilator that must be kept open for the essential operations of the ship...

  14. Epigenetic and Posttranslational Modifications in Light Signal Transduction and the Circadian Clock in Neurospora crassa

    Directory of Open Access Journals (Sweden)

    Marco Proietto

    2015-07-01

    Full Text Available Blue light, a key abiotic signal, regulates a wide variety of physiological processes in many organisms. One of these phenomena is the circadian rhythm presents in organisms sensitive to the phase-setting effects of blue light and under control of the daily alternation of light and dark. Circadian clocks consist of autoregulatory alternating negative and positive feedback loops intimately connected with the cellular metabolism and biochemical processes. Neurospora crassa provides an excellent model for studying the molecular mechanisms involved in these phenomena. The White Collar Complex (WCC, a blue-light receptor and transcription factor of the circadian oscillator, and Frequency (FRQ, the circadian clock pacemaker, are at the core of the Neurospora circadian system. The eukaryotic circadian clock relies on transcriptional/translational feedback loops: some proteins rhythmically repress their own synthesis by inhibiting the activity of their transcriptional factors, generating self-sustained oscillations over a period of about 24 h. One of the basic mechanisms that perpetuate self-sustained oscillations is post translation modification (PTM. The acronym PTM generically indicates the addition of acetyl, methyl, sumoyl, or phosphoric groups to various types of proteins. The protein can be regulatory or enzymatic or a component of the chromatin. PTMs influence protein stability, interaction, localization, activity, and chromatin packaging. Chromatin modification and PTMs have been implicated in regulating circadian clock function in Neurospora. Research into the epigenetic control of transcription factors such as WCC has yielded new insights into the temporal modulation of light-dependent gene transcription. Here we report on epigenetic and protein PTMs in the regulation of the Neurospora crassa circadian clock. We also present a model that illustrates the molecular mechanisms at the basis of the blue light control of the circadian clock.

  15. Constraint is associated with earlier circadian phase and morningness: Confirmation of relationships between personality and circadian phase using a constant routine protocol.

    Science.gov (United States)

    Bullock, B; Murray, G; Anderson, J L; Cooper-O'Neill, T; Gooley, J J; Cain, S W; Lockley, S W

    2017-01-01

    Associations among personality, diurnal preference, and circadian phase were investigated using a constant routine laboratory protocol. One hundred and sixty-eight healthy participants aged 18-30 years (Women n = 68) completed either a 30- or 50-hour constant routine under dim-light conditions (<3 lux), during which circadian phase was measured from core body temperature and melatonin. Prior to laboratory admission, self-report measures of personality and diurnal preference were also obtained. The personality trait of Constraint correlated positively with morning diurnal preference and earlier circadian phase, with circadian phase partially mediating the relationship between Constraint and diurnal preference. No other personality variables correlated with circadian phase. Sex was an important covariate in several of the relationships investigated due to lower levels of Constraint and later CBT phase amongst men and was thus controlled for in all relevant analyses. Findings from this highly controlled study are consistent with previous field research in suggesting that earlier circadian phase is associated with the personality trait of Constraint.

  16. Unraveling the circadian clock in Arabidopsis.

    Science.gov (United States)

    Wang, Xiaoxue; Ma, Ligeng

    2013-02-01

    The circadian clock is an endogenous timing system responsible for coordinating an organism's biological processes with its environment. Interlocked transcriptional feedback loops constitute the fundamental architecture of the circadian clock. In Arabidopsis, three feedback loops, the core loop, morning loop and evening loop, comprise a network that is the basis of the circadian clock. The components of these three loops are regulated in distinct ways, including transcriptional, post-transcriptional and posttranslational mechanisms. The discovery of the DNA-binding and repressive activities of TOC1 has overturned our initial concept of its function in the circadian clock. The alternative splicing of circadian clock-related genes plays an essential role in normal functioning of the clock and enables organisms to sense environmental changes. In this review, we describe the regulatory mechanisms of the circadian clock that have been identified in Arabidopsis.

  17. Effect of melatonin on endogenous circadian rhythm

    Institute of Scientific and Technical Information of China (English)

    XU Feng; WANG Min; ZANG Ling-he

    2008-01-01

    Objective To further authenticate the role of melatonin on endogenous biologic clock system. Methods Pinealectomized mice were used in the experiments, a series of circadian rhythm of physiology index, such as glucocorticoid, amino acid neurotransmitter, immune function, sensitivity of algesia and body temperature were measured. Results Effects of melatonin on endogenous circadian rhythm roughly appeared four forms: 1) The model of inherent rhythm was invariant, but midvalue was removed. 2) Pacing function: pinealectomy and melatonin administration changed amplitude of the circadian vibration of aspartate, peripheral blood WBC and serum hemolysin. 3) Phase of rhythm changed, such as the effects on percentage of lymphocyte and sensitivity of algesia. 4) No effect, the circadian rhythm of body temperature belong to this form Conclusions Melatonin has effects some circadian rhythm, and it can adjust endogenous inherent rhythm and make the rhythm keep step with environmental cycle. Melatonin may be a kind of Zeitgeber, Pineal gland might being a rhythm bearing organ to some circadian rhythm.

  18. Assignment of an essential role for the Neurospora frequency gene in circadian entrainment to temperature cycles.

    Science.gov (United States)

    Pregueiro, Antonio M; Price-Lloyd, Nathan; Bell-Pedersen, Deborah; Heintzen, Christian; Loros, Jennifer J; Dunlap, Jay C

    2005-02-08

    Circadian systems include slave oscillators and central pacemakers, and the cores of eukaryotic circadian clocks described to date are composed of transcription and translation feedback loops (TTFLs). In the model system Neurospora, normal circadian rhythmicity requires a TTFL in which a White Collar complex (WCC) activates expression of the frequency (frq) gene, and the FRQ protein feeds back to attenuate that activation. To further test the centrality of this TTFL to the circadian mechanism in Neurospora, we used low-amplitude temperature cycles to compare WT and frq-null strains under conditions in which a banding rhythm was elicited. WT cultures were entrained to these temperature cycles. Unlike those normal strains, however, frq-null mutants did not truly entrain to the same cycles. Their peaks and troughs always occurred in the cold and warm periods, respectively, strongly suggesting that the rhythm in Neurospora lacking frq function simply is driven by the temperature cycles. Previous reports suggested that a FRQ-less oscillator (FLO) could be entrained to temperature cycles, rather than being driven, and speculated that the FLO was the underlying circadian-rhythm generator. These inferences appear to derive from the use of a phase reference point affected by both the changing waveform and the phase of the oscillation. Examination of several other phase markers as well as results of additional experimental tests indicate that the FLO is, at best, a slave oscillator to the TTFL, which underlies circadian rhythm generation in Neurospora.

  19. ADJUSTMENT, MAINTENANCE, AND REPAIR OF CROP HARVESTING MACHINERY. AGRICULTURAL MACHINERY--SERVICE OCCUPATIONS, MODULE NUMBER 11.

    Science.gov (United States)

    Ohio State Univ., Columbus. Center for Vocational and Technical Education.

    ONE OF A SERIES DESIGNED FOR HELPING TEACHERS PREPARE POSTSECONDARY-LEVEL STUDENTS FOR AGRICULTURAL MACHINERY SERVICE OCCUPATIONS AS PARTS MEN, MECHANICS, MECHANIC'S HELPERS, AND SERVICE SUPERVISORS, THIS GUIDE AIMS TO DEVELOP STUDENT COMPETENCY IN ADJUSTING, REPAIRING, AND MAINTAINING CROP HARVESTING MACHINERY. SUGGESTIONS FOR INTRODUCTION OF THE…

  20. Circadian regulators of intestinal lipid absorption

    OpenAIRE

    Hussain, M. Mahmood; Pan, Xiaoyue

    2015-01-01

    Among all the metabolites present in the plasma, lipids, mainly triacylglycerol and diacylglycerol, show extensive circadian rhythms. These lipids are transported in the plasma as part of lipoproteins. Lipoproteins are synthesized primarily in the liver and intestine and their production exhibits circadian rhythmicity. Studies have shown that various proteins involved in lipid absorption and lipoprotein biosynthesis show circadian expression. Further, intestinal epithelial cells express circa...

  1. Spatiotemporal Regulation of Nuclear Transport Machinery and Microtubule Organization

    Directory of Open Access Journals (Sweden)

    Naoyuki Okada

    2015-08-01

    Full Text Available Spindle microtubules capture and segregate chromosomes and, therefore, their assembly is an essential event in mitosis. To carry out their mission, many key players for microtubule formation need to be strictly orchestrated. Particularly, proteins that assemble the spindle need to be translocated at appropriate sites during mitosis. A small GTPase (hydrolase enzyme of guanosine triphosphate, Ran, controls this translocation. Ran plays many roles in many cellular events: nucleocytoplasmic shuttling through the nuclear envelope, assembly of the mitotic spindle, and reorganization of the nuclear envelope at the mitotic exit. Although these events are seemingly distinct, recent studies demonstrate that the mechanisms underlying these phenomena are substantially the same as explained by molecular interplay of the master regulator Ran, the transport factor importin, and its cargo proteins. Our review focuses on how the transport machinery regulates mitotic progression of cells. We summarize translocation mechanisms governed by Ran and its regulatory proteins, and particularly focus on Ran-GTP targets in fission yeast that promote spindle formation. We also discuss the coordination of the spatial and temporal regulation of proteins from the viewpoint of transport machinery. We propose that the transport machinery is an essential key that couples the spatial and temporal events in cells.

  2. Circadian Rhythm Control: Neurophysiological Investigations

    Science.gov (United States)

    Glotzbach, S. F.

    1985-01-01

    The suprachiasmatic nucleus (SCN) was implicated as a primary component in central nervous system mechanisms governing circadian rhythms. Disruption of the normal synchronization of temperature, activity, and other rhythms is detrimental to health. Sleep wake disorders, decreases in vigilance and performance, and certain affective disorders may result from or be exacerbated by such desynchronization. To study the basic neurophysiological mechanisms involved in entrainment of circadian systems by the environment, Parylene-coated, etched microwire electrode bundles were used to record extracellular action potentials from the small somata of the SCN and neighboring hypothalamic nuclei in unanesthetized, behaving animals. Male Wistar rats were anesthetized and chronically prepared with EEG ane EMG electrodes in addition to a moveable microdrive assembly. The majority of cells had firing rates 10 Hz and distinct populations of cells which had either the highest firing rate or lowest firing rate during sleep were seen.

  3. Circadian clocks are designed optimally

    CERN Document Server

    Hasegawa, Yoshihiko

    2014-01-01

    Circadian rhythms are acquired through evolution to increase the chances for survival by synchronizing to the daylight cycle. Reliable synchronization is realized through two trade-off properties: regularity to keep time precisely, and entrainability to synchronize the internal time with daylight. Since both properties have been tuned through natural selection, their adaptation can be formalized in the framework of mathematical optimization. By using a succinct model, we found that simultaneous optimization of regularity and entrainability entails inherent features of the circadian mechanism irrespective of model details. At the behavioral level we discovered the existence of a dead zone, a time during which light pulses neither advance nor delay the clock. At the molecular level we demonstrate the role-sharing of two light inputs, phase advance and delay, as is well observed in mammals. We also reproduce the results of phase-controlling experiments and predict molecular elements responsible for the clockwork...

  4. Human adipose tissue expresses intrinsic circadian rhythm in insulin sensitivity.

    Science.gov (United States)

    Carrasco-Benso, Maria P; Rivero-Gutierrez, Belen; Lopez-Minguez, Jesus; Anzola, Andrea; Diez-Noguera, Antoni; Madrid, Juan A; Lujan, Juan A; Martínez-Augustin, Olga; Scheer, Frank A J L; Garaulet, Marta

    2016-09-01

    In humans, insulin sensitivity varies according to time of day, with decreased values in the evening and at night. Mechanisms responsible for the diurnal variation in insulin sensitivity are unclear. We investigated whether human adipose tissue (AT) expresses intrinsic circadian rhythms in insulin sensitivity that could contribute to this phenomenon. Subcutaneous and visceral AT biopsies were obtained from extremely obese participants (body mass index, 41.8 ± 6.3 kg/m(2); 46 ± 11 y) during gastric-bypass surgery. To assess the rhythm in insulin signaling, AKT phosphorylation was determined every 4 h over 24 h in vitro in response to different insulin concentrations (0, 1, 10, and 100 nM). Data revealed that subcutaneous AT exhibited robust circadian rhythms in insulin signaling (P Insulin sensitivity reached its maximum (acrophase) around noon, being 54% higher than during midnight (P = 0.009). The amplitude of the rhythm was positively correlated with in vivo sleep duration (r = 0.53; P = 0.023) and negatively correlated with in vivo bedtime (r = -0.54; P = 0.020). No circadian rhythms were detected in visceral AT (P = 0.643). Here, we demonstrate the relevance of the time of the day for how sensitive AT is to the effects of insulin. Subcutaneous AT shows an endogenous circadian rhythm in insulin sensitivity that could provide an underlying mechanism for the daily rhythm in systemic insulin sensitivity.-Carrasco-Benso, M. P., Rivero-Gutierrez, B., Lopez-Minguez, J., Anzola, A., Diez-Noguera, A., Madrid, J. A., Lujan, J. A., Martínez-Augustin, O., Scheer, F. A. J. L., Garaulet, M. Human adipose tissue expresses intrinsic circadian rhythm in insulin sensitivity. © FASEB.

  5. Circadian rhythms, the molecular clock, and skeletal muscle.

    Science.gov (United States)

    Lefta, Mellani; Wolff, Gretchen; Esser, Karyn A

    2011-01-01

    Almost all organisms ranging from single cell bacteria to humans exhibit a variety of behavioral, physiological, and biochemical rhythms. In mammals, circadian rhythms control the timing of many physiological processes over a 24-h period, including sleep-wake cycles, body temperature, feeding, and hormone production. This body of research has led to defined characteristics of circadian rhythms based on period length, phase, and amplitude. Underlying circadian behaviors is a molecular clock mechanism found in most, if not all, cell types including skeletal muscle. The mammalian molecular clock is a complex of multiple oscillating networks that are regulated through transcriptional mechanisms, timed protein turnover, and input from small molecules. At this time, very little is known about circadian aspects of skeletal muscle function/metabolism but some progress has been made on understanding the molecular clock in skeletal muscle. The goal of this chapter is to provide the basic terminology and concepts of circadian rhythms with a more detailed review of the current state of knowledge of the molecular clock, with reference to what is known in skeletal muscle. Research has demonstrated that the molecular clock is active in skeletal muscles and that the muscle-specific transcription factor, MyoD, is a direct target of the molecular clock. Skeletal muscle of clock-compromised mice, Bmal1(-/-) and Clock(Δ19) mice, are weak and exhibit significant disruptions in expression of many genes required for adult muscle structure and metabolism. We suggest that the interaction between the molecular clock, MyoD, and metabolic factors, such as PGC-1, provide a potential system of feedback loops that may be critical for both maintenance and adaptation of skeletal muscle.

  6. Circadian rhythms and period expression in the Hawaiian cricket genus Laupala.

    Science.gov (United States)

    Fergus, Daniel J; Shaw, Kerry L

    2013-05-01

    Daily activity times and circadian rhythms of crickets have been a subject of behavioral and physiological study for decades. However, recent studies suggest that the underlying molecular mechanism of cricket endogenous clocks differ from the model of circadian rhythm generation in Drosophila. Here we examine the circadian free-running periods of walking and singing in two Hawaiian swordtail cricket species, Laupala cerasina and Laupala paranigra, that differ in the daily timing of mating related activities. Additionally, we examine variation in sequence and daily cycling of the period (per) gene transcript between these species. The species differed significantly in free-running period of singing, but did not differ significantly in the free-running period of locomotion. Like in Drosophila, per transcript abundance showed cycling consistent with a role in circadian rhythm generation. The amino acid differences identified between these species suggest a potential of the per gene in interspecific behavioral variation in Laupala.

  7. Circadian pancreatic enzyme pattern and relationship between secretory and motor activity in fasting humans.

    Science.gov (United States)

    Keller, Jutta; Layer, Peter

    2002-08-01

    It is unknown whether nonparallel pancreatic enzyme output occurs under basal conditions in humans. We aimed to determine whether the circadian or wake-sleep cycle influences the relationship among pancreatic enzymes or between pancreatic secretory and jejunal motor activity. Using orojejunal multilumen intubation, we measured enzyme outputs and proximal jejunal motility index during consecutive daytime and nighttime periods in each of seven fasting, healthy volunteers. Enzyme outputs were correlated tightly during daytime phases of wakefulness and nighttime phases of sleep (r > 0.72, P activity was directly correlated with jejunal motility index (r > 0.50, P enzymes dominates throughout the circadian cycle. Nonparallel secretion during nocturnal phases of wakefulness may be due to merely circadian effects or to the coupling of the wake-sleep and the circadian cycle. The association between fluctuations of secretory and motor activity appears to be particularly tight during the night.

  8. Circadian rhythm of activity during the annual phases in the European quail, Coturnix coturnix.

    Science.gov (United States)

    Lumineau, S; Guyomarc'h, C

    2000-09-01

    Migratory birds, such as the European quail, present an annual cycle with the following phases: moult, fattening, migration and reproduction. This study aimed at determining how variations in the circadian rhythm of feeding during the annual cycle took endogenous rhythmic characteristics into account. The birds (n = 8) were maintained under constant dim light from the age of 1 to 9 months. Feeding activity was recorded using infra-red detectors. The birds expressed all the phases, except migration. Activity was arrhythmic when they were moulting. A circadian rhythm of feeding activity appeared during the fattening phase. In males, the circadian period lengthened and the clarity of the rhythm increased during sexual development. These results appear to confirm the effects of physiological state on the temporal organisation of activity. Variations of the circadian rhythm could influence the ability to synchronize with exogenous cycles such as the alternation of day and night.

  9. Two decades of circadian time.

    Science.gov (United States)

    Hastings, M H; Maywood, E S; Reddy, A B

    2008-06-01

    Circadian rhythms coordinate our physiology at a fundamental level. Over the last 20 years, we have witnessed a paradigm shift in our perception of what the clocks driving such rhythms actually are, moving from 'black boxes' to talking about autoregulatory transcriptional/post-translational feedback loops with identified molecular components. We also now know that the pacemaker of the suprachiasmatic nuclei (SCN) is not our only clock but quite the opposite because circadian clocks abound in our bodies, driving local rhythms of cellular metabolism, and synchronised to each other and to solar time, by cues from the SCN. This discovery of dispersed local clocks has far-reaching implications for understanding our physiology and the pathological consequences of clock dysfunction, revealing that clocks are critical in a variety of metabolic and neurological conditions, all of which have long-term morbidity attributable to them. Without the currently available molecular framework, these insights would have not have been possible. In the circadian future, a growing appreciation of the systems-level functioning of these clocks and their various cerebral and visceral outputs, will likely stimulate the development of novel therapies for major illnesses.

  10. Mitochondrial Machineries for Protein Import and Assembly.

    Science.gov (United States)

    Wiedemann, Nils; Pfanner, Nikolaus

    2017-03-15

    Mitochondria are essential organelles with numerous functions in cellular metabolism and homeostasis. Most of the >1,000 different mitochondrial proteins are synthesized as precursors in the cytosol and are imported into mitochondria by five transport pathways. The protein import machineries of the mitochondrial membranes and aqueous compartments reveal a remarkable variability of mechanisms for protein recognition, translocation, and sorting. The protein translocases do not operate as separate entities but are connected to each other and to machineries with functions in energetics, membrane organization, and quality control. Here, we discuss the versatility and dynamic organization of the mitochondrial protein import machineries. Elucidating the molecular mechanisms of mitochondrial protein translocation is crucial for understanding the integration of protein translocases into a large network that controls organelle biogenesis, function, and dynamics. Expected final online publication date for the Annual Review of Biochemistry Volume 86 is June 20, 2017. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  11. Chronic electromyographic analysis of circadian locomotor activity in crayfish.

    Science.gov (United States)

    Tomina, Yusuke; Kibayashi, Akihiro; Yoshii, Taishi; Takahata, Masakazu

    2013-07-15

    Animals generally exhibit circadian rhythms of locomotor activity. They initiate locomotor behavior not only reflexively in response to external stimuli but also spontaneously in the absence of any specific stimulus. The neuronal mechanisms underlying circadian locomotor activity can, therefore, be based on the rhythmic changes in either reflexive efficacy or endogenous activity. In crayfish Procambarus clarkii, it can be determined by analyzing electromyographic (EMG) patterns of walking legs whether the walking behavior is initiated reflexively or spontaneously. In this study, we examined quantitatively the leg muscle activity that underlies the locomotor behavior showing circadian rhythms in crayfish. We newly developed a chronic EMG recording system that allowed the animal to freely behave under a tethered condition for more than 10 days. In the LD condition in which the animals exhibited LD entrainment, the rhythmic burst activity of leg muscles for stepping behavior was preceded by non-rhythmic tonic activation that lasted for 1323±488ms when the animal initiated walking. In DD and LL free-running conditions, the pre-burst activation lasted for 1779±31 and 1517±39ms respectively. In the mechanical stimulus-evoked walking, the pre-burst activation ended within 79±6ms. These data suggest that periodic changes in the crayfish locomotor activity under the condition of LD entrainment or free-running are based on activity changes in the spontaneous initiation mechanism of walking behavior rather than those in the sensori-motor pathway connecting mechanoreceptors with leg movements.

  12. Circadian regulation of abiotic stress tolerance in plants.

    Science.gov (United States)

    Grundy, Jack; Stoker, Claire; Carré, Isabelle A

    2015-01-01

    Extremes of temperatures, drought and salinity cause widespread crop losses throughout the world and impose severe limitations on the amount of land that can be used for agricultural purposes. Hence, there is an urgent need to develop crops that perform better under such abiotic stress conditions. Here, we discuss intriguing, recent evidence that circadian clock contributes to plants' ability to tolerate different types of environmental stress, and to acclimate to them. The clock controls expression of a large fraction of abiotic stress-responsive genes, as well as biosynthesis and signaling downstream of stress response hormones. Conversely, abiotic stress results in altered expression and differential splicing of the clock genes, leading to altered oscillations of downstream stress-response pathways. We propose a range of mechanisms by which this intimate coupling between the circadian clock and environmental stress-response pathways may contribute to plant growth and survival under abiotic stress.

  13. Bile acid-regulated peroxisome proliferator-activated receptor-α (PPARα) activity underlies circadian expression of intestinal peptide absorption transporter PepT1/Slc15a1.

    Science.gov (United States)

    Okamura, Ayako; Koyanagi, Satoru; Dilxiat, Adila; Kusunose, Naoki; Chen, Jia Jun; Matsunaga, Naoya; Shibata, Shigenobu; Ohdo, Shigehiro

    2014-09-05

    Digested proteins are mainly absorbed as small peptides composed of two or three amino acids. The intestinal absorption of small peptides is mediated via only one transport system: the proton-coupled peptide transporter-1 (PepT1) encoded from the soluble carrier protein Slc15a1. In mammals, intestinal expression of PepT1/Slc15a1 oscillates during the daily feeding cycle. Although the oscillation in the intestinal expression of PepT1/Slc15a1 is suggested to be controlled by molecular components of circadian clock, we demonstrated here that bile acids regulated the oscillation of PepT1/Slc15a1 expression through modulating the activity of peroxisome proliferator-activated receptor α (PPARα). Nocturnally active mice mainly consumed their food during the dark phase. PPARα activated the intestinal expression of Slc15a1 mRNA during the light period, and protein levels of PepT1 peaked before the start of the dark phase. After food intake, bile acids accumulated in intestinal epithelial cells. Intestinal accumulated bile acids interfered with recruitment of co-transcriptional activator CREB-binding protein/p300 on the promoter region of Slc15a1 gene, thereby suppressing PPARα-mediated transactivation of Slc15a1. The time-dependent suppression of PPARα-mediated transactivation by bile acids caused an oscillation in the intestinal expression of PepT1/Slc15a1 during the daily feeding cycle that led to circadian changes in the intestinal absorption of small peptides. These findings suggest a molecular clock-independent mechanism by which bile acid-regulated PPARα activity governs the circadian expression of intestinal peptide transporter.

  14. The metabolic sensor AKIN10 modulates the Arabidopsis circadian clock in a light-dependent manner.

    Science.gov (United States)

    Shin, Jieun; Sánchez-Villarreal, Alfredo; Davis, Amanda M; Du, Shen-Xiu; Berendzen, Kenneth W; Koncz, Csaba; Ding, Zhaojun; Li, Cuiling; Davis, Seth J

    2017-07-01

    Plants generate rhythmic metabolism during the repetitive day/night cycle. The circadian clock produces internal biological rhythms to synchronize numerous metabolic processes such that they occur at the required time of day. Metabolism conversely influences clock function by controlling circadian period and phase and the expression of core-clock genes. Here, we show that AKIN10, a catalytic subunit of the evolutionarily conserved key energy sensor sucrose non-fermenting 1 (Snf1)-related kinase 1 (SnRK1) complex, plays an important role in the circadian clock. Elevated AKIN10 expression led to delayed peak expression of the circadian clock evening-element GIGANTEA (GI) under diurnal conditions. Moreover, it lengthened clock period specifically under light conditions. Genetic analysis showed that the clock regulator TIME FOR COFFEE (TIC) is required for this effect of AKIN10. Taken together, we propose that AKIN10 conditionally works in a circadian clock input pathway to the circadian oscillator. © 2017 John Wiley & Sons Ltd.

  15. Machinery condition monitoring principles and practices

    CERN Document Server

    Mohanty, Amiya Ranjan

    2015-01-01

    Find the Fault in the MachinesDrawing on the author's more than two decades of experience with machinery condition monitoring and consulting for industries in India and abroad, Machinery Condition Monitoring: Principles and Practices introduces the practicing engineer to the techniques used to effectively detect and diagnose faults in machines. Providing the working principle behind the instruments, the important elements of machines as well as the technique to understand their conditions, this text presents every available method of machine fault detection occurring in machines in general, an

  16. Modeling the emergence of circadian rhythms in a clock neuron network.

    Directory of Open Access Journals (Sweden)

    Luis Diambra

    Full Text Available Circadian rhythms in pacemaker cells persist for weeks in constant darkness, while in other types of cells the molecular oscillations that underlie circadian rhythms damp rapidly under the same conditions. Although much progress has been made in understanding the biochemical and cellular basis of circadian rhythms, the mechanisms leading to damped or self-sustained oscillations remain largely unknown. There exist many mathematical models that reproduce the circadian rhythms in the case of a single cell of the Drosophila fly. However, not much is known about the mechanisms leading to coherent circadian oscillation in clock neuron networks. In this work we have implemented a model for a network of interacting clock neurons to describe the emergence (or damping of circadian rhythms in Drosophila fly, in the absence of zeitgebers. Our model consists of an array of pacemakers that interact through the modulation of some parameters by a network feedback. The individual pacemakers are described by a well-known biochemical model for circadian oscillation, to which we have added degradation of PER protein by light and multiplicative noise. The network feedback is the PER protein level averaged over the whole network. In particular, we have investigated the effect of modulation of the parameters associated with (i the control of net entrance of PER into the nucleus and (ii the non-photic degradation of PER. Our results indicate that the modulation of PER entrance into the nucleus allows the synchronization of clock neurons, leading to coherent circadian oscillations under constant dark condition. On the other hand, the modulation of non-photic degradation cannot reset the phases of individual clocks subjected to intrinsic biochemical noise.

  17. Shift work: health, performance and safety problems, traditional countermeasures, and innovative management strategies to reduce circadian misalignment

    Directory of Open Access Journals (Sweden)

    Smith MR

    2012-09-01

    Full Text Available Mark R Smith, Charmane I EastmanBiological Rhythms Research Laboratory, Rush University Medical Center, Chicago, IL, USAAbstract: There are three mechanisms that may contribute to the health, performance, and safety problems associated with night-shift work: (1 circadian misalignment between the internal circadian clock and activities such as work, sleep, and eating, (2 chronic, partial sleep deprivation, and (3 melatonin suppression by light at night. The typical countermeasures, such as caffeine, naps, and melatonin (for its sleep-promoting effect, along with education about sleep and circadian rhythms, are the components of most fatigue risk-management plans. We contend that these, while better than nothing, are not enough because they do not address the underlying cause of the problems, which is circadian misalignment. We explain how to reset (phase-shift the circadian clock to partially align with the night-work, day-sleep schedule, and thus reduce circadian misalignment while preserving sleep and functioning on days off. This involves controlling light and dark using outdoor light exposure, sunglasses, sleep in the dark, and a little bright light during night work. We present a diagram of a sleep-and-light schedule to reduce circadian misalignment in permanent night work, or a rotation between evenings and nights, and give practical advice on how to implement this type of plan.Keywords: circadian rhythms, night work, bright light, phase-shifting, sleep, melatonin

  18. Circadian regulation of cell cycle: Molecular connections between aging and the circadian clock.

    Science.gov (United States)

    Khapre, Rohini V; Samsa, William E; Kondratov, Roman V

    2010-09-01

    The circadian clock generates oscillations in physiology and behavior, known as circadian rhythms. Links between the circadian clock genes Periods, Bmal1, and Cryptochromes and aging and cancer are emerging. Circadian clock gene expression is changed in human pathologies, and transgenic mice with mutations in clock genes develop cancer and premature aging. Control of genome integrity and cell proliferation play key roles in the development of age-associated pathologies and carcinogenesis. Here, we review recent data on the connection between the circadian clock and control of the cell cycle. The circadian clock regulates the activity and expression of several critical cell cycle and cell cycle check-point-related proteins, and in turn cell cycle-associated proteins regulate circadian clock proteins. DNA damage can reset the circadian clock, which provides a molecular mechanism for reciprocal regulation between the circadian clock and the cell cycle. This circadian clock-dependent control of cell proliferation, together with other known physiological functions of the circadian clock such as the control of metabolism, oxidative and genotoxic stress response, and DNA repair, opens new horizons for understanding the mechanisms behind aging and carcinogenesis.

  19. Circadian- and Light-Dependent Regulation of Resting Membrane Potential and Spontaneous Action Potential Firing of Drosophila Circadian Pacemaker Neurons

    OpenAIRE

    Sheeba, Vasu; Gu, Huaiyu; Sharma, Vijay K.; O'Dowd, Diane K.; Holmes, Todd C

    2007-01-01

    The ventral lateral neurons (LNvs) of adult Drosophila brain express oscillating clock proteins and regulate circadian behavior. Whole cell current-clamp recordings of large LNvs in freshly dissected Drosophila whole brain preparations reveal two spontaneous activity patterns that correlate with two underlying patterns of oscillating membrane potential: tonic and burst firing of sodium-dependent action potentials. Resting membrane potential and spontaneous action potential firing are rapidly ...

  20. Italian Textile Machinery Industry Focuses on Sustainability

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    As for fashion industry,Italian brands always play as one of the leaders influencing the global trends.This time,in Shanghai,the Italian textile machinery manufacturers highlight the latest proposals on sustainability and eco-friendly technology.

  1. Italian Textite Machinery Industry Focuses on Sustainability

    Institute of Scientific and Technical Information of China (English)

    Wang Ting

    2010-01-01

    @@ At the ITMA Asia+CITME 2010,which was held on June 22at the Shanghai New International Expo Centre in Shanghai,Italian textile machinery manufacturers represented one of the largest foreign delegations: 115exhibitors occupying a total surface area of about 4,000 sq.meters.

  2. Active Vibration Dampers For Rotating Machinery

    Science.gov (United States)

    Kascack, Albert F.; Ropchock, John J.; Lakatos, Tomas F.; Montague, Gerald T.; Palazzolo, Alan; Lin, Reng Rong

    1994-01-01

    Active dampers developed to suppress vibrations in rotating machinery. Essentially feedback control systems and reciprocating piezoelectric actuators. Similar active damper containing different actuators described in LEW-14488. Concept also applicable to suppression of vibrations in stationary structures subject to winds and earthquakes. Active damper offers adjustable suppression of vibrations. Small and lightweight and responds faster to transients.

  3. CCPIT Machinery Exhibition Succeeded in Kuala Lumpur

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

      From August 18 to 20, 2005, China Council for the Promotion of International Trade(CCPIT) held China Machinery and Electronics Trade Exhibition, CME 2005 in Kuala Lumpur, the capital of Malaysia on behalf of China, a good job has been done.……

  4. CCPIT Machinery Exhibition Succeeded in Kuala Lumpur

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    @@ From August 18 to 20, 2005, China Council for the Promotion of International Trade(CCPIT) held China Machinery and Electronics Trade Exhibition, CME 2005 in Kuala Lumpur, the capital of Malaysia on behalf of China, a good job has been done.

  5. Brownian machinery in physics and biology

    OpenAIRE

    Hänggi, Peter

    2001-01-01

    Brownian machinery in physics and biology. - In: Noise in physical systems and 1/f fluctuations : proceedings of the 16th internat. conference, Gainesville, Fl., 22-25 Oct. 2001 / Ed.: Gijs Bosman. - New Jersey u.a. : World Scientific, 2001. - S. 397-399

  6. Computational design of hydrogen fluid machinery

    Energy Technology Data Exchange (ETDEWEB)

    Kaupert, K.A. [Ebara Cryodynamics Div., Sparks, NV (United States)

    2001-06-01

    This paper presented computational design methods for liquid hydrogen fluid machinery for which the aerospace industry holds a particular interest. The main design points are reliability, efficiency and predictability. The methods described here were based on experience gained in the liquefied natural gas sector. The main design validation tools presented in this paper were computational fluid dynamics, computational rotordynamics, and computational stress analysis. Recent advances have made it possible to incorporate the influence of unsteady phenomena. These new design techniques make it possible to increase the reliability, efficiency and predictability of fluid machinery. A design example for an Ebara Cryodynamics multi-stage impeller/diffuser-return vane combination operating in liquefied natural gas was presented. The fluid machinery characteristics were compared for liquid hydrogen and liquefied natural gas to demonstrate the technical feasibility of industrial liquid hydrogen fluid machinery. Currently, no significant demand exists for liquid hydrogen turbomachinery except for the rocket engine industry. But the emergence of the hydrogen economy will promote the growth in liquefied natural gas and or liquid hydrogen cryogenic turbomachinery. 11 refs., 3 tabs., 6 figs.

  7. Development of cortisol circadian rhythm in infancy.

    NARCIS (Netherlands)

    Weerth, C. de; Zijl, R.H.

    2003-01-01

    BACKGROUND AND AIMS: Cortisol is the final product of the hypothalamus-pituitary-adrenal (HPA) axis. It is secreted in a pulsatile fashion that displays a circadian rhythm. Infants are born without a circadian rhythm in cortisol and they acquire it during their first year of life. Studies do not agr

  8. Circadian clocks: Omnes viae Romam ducunt.

    Science.gov (United States)

    Roenneberg, T; Merrow, M

    2000-10-19

    The circadian clock in all organisms is so intimately linked to light reception that it appears as if evolution has simply wired a timer into the mechanism that processes photic information. Several recent studies have provided new insights into the role of light input pathways in the circadian system of Arabidopsis.

  9. Circadian variation in the pharmacokinetics of verapamil

    DEFF Research Database (Denmark)

    Jespersen, C M; Frederiksen, M; Hansen, J F;

    1989-01-01

    Circadian variation in the metabolism of verapamil was investigated in 10 patients with stable angina pectoris during treatment with sustained-release verapamil 360 mg at 08.00 h or 22.0 h. No major difference in exercise parameters was found. During the evening dosage schedule a significantly gr...... or to circadian variation in hepatic microsomal metabolism....

  10. Circadian dysfunction induces leptin resistance in mice

    Science.gov (United States)

    Circadian disruption is associated with obesity, implicating the central clock in body weight control. Our comprehensive screen of wild-type and three circadian mutant mouse models, with or without chronic jet lag, shows that distinct genetic and physiologic interventions differentially disrupt over...

  11. Circadian control sheds light on fungal bioluminescence.

    Science.gov (United States)

    Oliveira, Anderson G; Stevani, Cassius V; Waldenmaier, Hans E; Viviani, Vadim; Emerson, Jillian M; Loros, Jennifer J; Dunlap, Jay C

    2015-03-30

    Bioluminescence, the creation and emission of light by organisms, affords insight into the lives of organisms doing it. Luminous living things are widespread and access diverse mechanisms to generate and control luminescence [1-5]. Among the least studied bioluminescent organisms are phylogenetically rare fungi-only 71 species, all within the ∼ 9,000 fungi of the temperate and tropical Agaricales order-are reported from among ∼ 100,000 described fungal species [6, 7]. All require oxygen [8] and energy (NADH or NADPH) for bioluminescence and are reported to emit green light (λmax 530 nm) continuously, implying a metabolic function for bioluminescence, perhaps as a byproduct of oxidative metabolism in lignin degradation. Here, however, we report that bioluminescence from the mycelium of Neonothopanus gardneri is controlled by a temperature-compensated circadian clock, the result of cycles in content/activity of the luciferase, reductase, and luciferin that comprise the luminescent system. Because regulation implies an adaptive function for bioluminescence, a controversial question for more than two millennia [8-15], we examined interactions between luminescent fungi and insects [16]. Prosthetic acrylic resin "mushrooms," internally illuminated by a green LED emitting light similar to the bioluminescence, attract staphilinid rove beetles (coleopterans), as well as hemipterans (true bugs), dipterans (flies), and hymenopterans (wasps and ants), at numbers far greater than dark control traps. Thus, circadian control may optimize energy use for when bioluminescence is most visible, attracting insects that can in turn help in spore dispersal, thereby benefitting fungi growing under the forest canopy, where wind flow is greatly reduced.

  12. Circadian oscillators in the mouse brain

    DEFF Research Database (Denmark)

    Rath, Martin F; Rovsing, Louise; Møller, Morten

    2014-01-01

    and granular cell layers of the cerebellar cortex of the mouse brain. Among these, Per1, Per2, Cry1, Arntl, and Nr1d1 exhibit circadian rhythms suggesting that local running circadian oscillators reside within neurons of the mouse neocortex and cerebellar cortex. The temporal expression profiles of clock genes......The circadian timekeeper of the mammalian brain resides in the suprachiasmatic nucleus of the hypothalamus (SCN), and is characterized by rhythmic expression of a set of clock genes with specific 24-h daily profiles. An increasing amount of data suggests that additional circadian oscillators...... residing outside the SCN have the capacity to generate peripheral circadian rhythms. We have recently shown the presence of SCN-controlled oscillators in the neocortex and cerebellum of the rat. The function of these peripheral brain clocks is unknown, and elucidating this could involve mice...

  13. Neurobiology of the circadian system: meeting metabolism

    Directory of Open Access Journals (Sweden)

    Mendoza, Jorge

    2009-06-01

    Full Text Available The basic principles of physiology postulated the necessity of the constancy of the internal environment to maintain a physiological equilibrium and do not front serious consequences in health. Now we know that physiology is rhythmic and that a break of this rhythmicity can generate serious consequences in health which even could be lethal. Circadian clocks, headed by the suprachiasmatic nucleus in the central nervous system, are the responsible for the generation of circadian rhythms. These clocks are affected by external signals as light (day-night cycles and feeding. This review examines the basic principles of the circadian system and the current knowledge in the neurobiology of biological clocks, making emphasis in the relationship between the circadian system, feeding behaviour, nutrition and metabolism, and the consequences that occur when these systems are not coordinated each other, as the development of metabolic and circadian pathologies.

  14. Impaired leukocyte trafficking and skin inflammatory responses in hamsters lacking a functional circadian system.

    Science.gov (United States)

    Prendergast, Brian J; Cable, Erin J; Patel, Priyesh N; Pyter, Leah M; Onishi, Kenneth G; Stevenson, Tyler J; Ruby, Norman F; Bradley, Sean P

    2013-08-01

    The immune system is under strong circadian control, and circadian desynchrony is a risk factor for metabolic disorders, inflammatory responses and cancer. Signaling pathways that maintain circadian rhythms (CRs) in immune function in vivo, and the mechanisms by which circadian desynchrony impairs immune function, remain to be fully identified. These experiments tested the hypothesis that the hypothalamic circadian pacemaker in the suprachiasmatic nucleus (SCN) drives CRs in the immune system, using a non-invasive model of SCN circadian arrhythmia. Robust CRs in blood leukocyte trafficking, with a peak during the early light phase (ZT4) and nadir in the early dark phase (ZT18), were absent in arrhythmic hamsters, as were CRs in spleen clock gene (per1, bmal1) expression, indicating that a functional pacemaker in the SCN is required for the generation of CRs in leukocyte trafficking and for driving peripheral clocks in secondary lymphoid organs. Pinealectomy was without effect on CRs in leukocyte trafficking, but abolished CRs in spleen clock gene expression, indicating that nocturnal melatonin secretion is necessary for communicating circadian time information to the spleen. CRs in trafficking of antigen presenting cells (CD11c(+) dendritic cells) in the skin were abolished, and antigen-specific delayed-type hypersensitivity skin inflammatory responses were markedly impaired in arrhythmic hamsters. The SCN drives robust CRs in leukocyte trafficking and lymphoid clock gene expression; the latter of which is not expressed in the absence of melatonin. Robust entrainment of the circadian pacemaker provides a signal critical to diurnal rhythms in immunosurveilliance and optimal memory T-cell dependent immune responses. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. Photic sensitivity ranges of hamster pupillary and circadian phase responses do not overlap.

    Science.gov (United States)

    Hut, Roelof A; Oklejewicz, Malgorzata; Rieux, Camille; Cooper, Howard M

    2008-02-01

    Mammalian retinal photoreceptors form an irradiance detection system that drives many nonvisual responses to light such as pupil reflex and resetting of the circadian clock. To understand the role of pupil size in circadian light responses, pupil diameter was pharmacologically manipulated and the effect on behavioral phase shifts at different irradiance levels was studied in the Syrian hamster. Dose-response curves for steady-state pupil size and for behavioral phase shifts were constructed for 3 pupil conditions (dilated, constricted, and control). Retinal irradiance was calculated from corneal irradiance, pupil size, retinal surface area, and absorption of ocular media. The sensitivity of photic responses to retinal irradiance is approximately 1.5 log units higher than to corneal irradiance. When plotted against corneal irradiance, pharmacological pupil constriction reduces the light sensitivity of the circadian system, but pupil dilation has no effect. As expected, when plotted against retinal irradiance all dose-response curves superimposed, confirming that the circadian system responds to photon flux on the retina. Pupil dilation does not increase the circadian response to increasing irradiance, since the response of the circadian system attains saturation at irradiance levels lower than those required to induce pupil constriction. The main finding shows that due to the different response sensitivities, the effect of pupil constriction on the light sensitivity of the circadian system in the hamster under natural conditions is virtually negligible. We further suggest the existence of distinct modulating mechanisms for the differential retinal irradiance sensitivity of the pupil system and the circadian system, which enables the different responses to be tuned to their specific tasks while using similar photoreceptive input.

  16. Does the core circadian clock in the moss Physcomitrella patens (Bryophyta) comprise a single loop?

    Science.gov (United States)

    Holm, Karl; Källman, Thomas; Gyllenstrand, Niclas; Hedman, Harald; Lagercrantz, Ulf

    2010-06-15

    The endogenous circadian clock allows the organism to synchronize processes both to daily and seasonal changes. In plants, many metabolic processes such as photosynthesis, as well as photoperiodic responses, are under the control of a circadian clock. Comparative studies with the moss Physcomitrella patens provide the opportunity to study many aspects of land plant evolution. Here we present a comparative overview of clock-associated components and the circadian network in the moss P. patens. The moss P. patens has a set of conserved circadian core components that share genetic relationship and gene expression patterns with clock genes of vascular plants. These genes include Myb-like transcription factors PpCCA1a and PpCCA1b, pseudo-response regulators PpPRR1-4, and regulatory elements PpELF3, PpLUX and possibly PpELF4. However, the moss lacks homologs of AtTOC1, AtGI and the AtZTL-family of genes, which can be found in all vascular plants studied here. These three genes constitute essential components of two of the three integrated feed-back loops in the current model of the Arabidopsis circadian clock mechanism. Consequently, our results suggest instead a single loop circadian clock in the moss. Possibly as a result of this, temperature compensation of core clock gene expression appears to be decreased in P. patens. This study is the first comparative overview of the circadian clock mechanism in a basal land plant, the moss P. patens. Our results indicate that the moss clock mechanism may represent an ancestral state in contrast to the more complex and partly duplicated structure of subsequent land plants. These findings may provide insights into the understanding of the evolution of circadian network topology.

  17. Reciprocal interaction of the circadian clock with the iron homeostasis network in Arabidopsis.

    Science.gov (United States)

    Hong, Sunghyun; Kim, Sun A; Guerinot, Mary Lou; McClung, C Robertson

    2013-02-01

    In plants, iron (Fe) uptake and homeostasis are critical for survival, and these processes are tightly regulated at the transcriptional and posttranscriptional levels. Circadian clocks are endogenous oscillating mechanisms that allow an organism to anticipate environmental changes to coordinate biological processes both with one another and with the environmental day/night cycle. The plant circadian clock controls many physiological processes through rhythmic expression of transcripts. In this study, we examined the expression of three Fe homeostasis genes (IRON REGULATED TRANSPORTER1 [IRT1], BASIC HELIX LOOP HELIX39, and FERRITIN1) in Arabidopsis (Arabidopsis thaliana) using promoter:LUCIFERASE transgenic lines. Each of these promoters showed circadian regulation of transcription. The circadian clock monitors a number of clock outputs and uses these outputs as inputs to modulate clock function. We show that this is also true for Fe status. Fe deficiency results in a lengthened circadian period. We interrogated mutants impaired in the Fe homeostasis response, including irt1-1, which lacks the major high-affinity Fe transporter, and fit-2, which lacks Fe deficiency-induced TRANSCRIPTION FACTOR1, a basic helix-loop-helix transcription factor necessary for induction of the Fe deficiency response. Both mutants exhibit symptoms of Fe deficiency, including lengthened circadian period. To determine which components are involved in this cross talk between the circadian and Fe homeostasis networks, we tested clock- or Fe homeostasis-related mutants. Mutants defective in specific clock gene components were resistant to the change in period length under different Fe conditions observed in the wild type, suggesting that these mutants are impaired in cross talk between Fe homeostasis and the circadian clock.

  18. GW182 controls Drosophila circadian behavior and PDF-receptor signaling.

    Science.gov (United States)

    Zhang, Yong; Emery, Patrick

    2013-04-10

    The neuropeptide PDF is crucial for Drosophila circadian behavior: it keeps circadian neurons synchronized. Here, we identify GW182 as a key regulator of PDF signaling. Indeed, GW182 downregulation results in phenotypes similar to those of Pdf and Pdf-receptor (Pdfr) mutants. gw182 genetically interacts with Pdfr and cAMP signaling, which is essential for PDFR function. GW182 mediates miRNA-dependent gene silencing through its interaction with AGO1. Consistently, GW182's AGO1 interaction domain is required for GW182's circadian function. Moreover, our results indicate that GW182 modulates PDFR signaling by silencing the expression of the cAMP phosphodiesterase DUNCE. Importantly, this repression is under photic control, and GW182 activity level--which is limiting in circadian neurons--influences the responses of the circadian neural network to light. We propose that GW182's gene silencing activity functions as a rheostat for PDFR signaling and thus profoundly impacts the circadian neural network and its response to environmental inputs. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Critical Role of the Circadian Clock in Memory Formation: Lessons from Aplysia

    Directory of Open Access Journals (Sweden)

    Lisa Carlson Lyons

    2011-12-01

    Full Text Available Unraveling the complexities of learning and the formation of memory requires identification of the cellular and molecular processes through which neural plasticity arises as well as recognition of the conditions or factors through which those processes are modulated. With its relatively simple nervous system, the marine mollusk Aplysia californica has proven an outstanding model system for studies of memory formation and identification of the molecular mechanisms underlying learned behaviors, including classical and operant associative learning paradigms and non-associative behaviors. In vivo behavioral studies in Aplysia have significantly furthered our understanding of how the endogenous circadian clock modulates memory formation. Sensitization of the tail-siphon withdrawal reflex represents a defensive non-associative learned behavior for which the circadian clock strongly modulates intermediate and long-term memory formation. Likewise, Aplysia exhibit circadian rhythms in long-term memory, but not short-term memory, for an operant associative learning paradigm. This review focuses on circadian modulation of intermediate and long-term memory and the putative mechanisms through which this modulation occurs. Additionally, potential functions and the adaptive advantages of time of day pressure on memory formation are considered. The influence of the circadian clock on learning and memory crosses distant phylogeny highlighting the evolutionary importance of the circadian clock on metabolic, physiological and behavioral processes. Thus, studies in a simple invertebrate model system have and will continue to provide critical mechanistic insights to complementary processes in higher organisms.

  20. Micro-managing the circadian clock: The role of microRNAs in biological timekeeping.

    Science.gov (United States)

    Mehta, Neel; Cheng, Hai-Ying M

    2013-10-09

    Evolved under the selective pressures of a 24-h world, circadian timekeeping mechanisms are present in virtually all living organisms to coordinate daily rhythms in physiology and behavior. Until recently, the circadian clock was modeled as simple, interlocked transcription-translation feedback loops driving rhythms in gene expression of a handful of core clock genes. However, it has become evident that circadian clock regulation is immensely more complex than once thought and involves posttranscriptional, translational and posttranslational mechanisms. In particular, there has been a growing awareness of the vital role played by microRNAs (miRNAs) in regulating various aspects of circadian clock function. In this review, we will summarize our current knowledge of miRNA-dependent regulation of the circadian timing system in multiple organisms, including flies, mammals and higher plants. We will also discuss future perspectives for research on the role of miRNAs and noncoding RNAs in circadian regulation of health and disease. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Quantifying the robustness of circadian oscillations at the single-cell level

    Science.gov (United States)

    Lambert, Guillaume; Rust, Michael

    2014-03-01

    Cyanobacteria are light-harvesting microorganisms that contribute to 30% of the photosynthetic activity on Earth and contain one of the simplest circadian systems in the animal kingdom. In Synechococcus elongatus , a species of freshwater cyanobacterium, circadian oscillations are regulated by the KaiABC system, a trio of interacting proteins that act as a biomolecular pacemaker of the circadian system. While the core oscillator precisely anticipates Earth's 24h light/dark cycle, it is unclear how much individual cells benefit from the expression and maintenance of a circadian clock. By studying the growth dynamics of individual S . elongatus cells under sudden light variations, we show that several aspects of cellular growth, such as a cell's division probability and its elongation rate, are tightly coupled to the circadian clock. We propose that the evolution and maintenance of a circadian clock increases the fitness of cells by allowing them to take advantage of cyclical light/dark environments by alternating between two phenotypes: expansionary, where cells grow and divide at a fast pace during the first part of the day, and conservative, where cells enter a more quiescent state to better prepare to the stresses associated with the night's prolonged darkness.

  2. Daily changes in ultraviolet light levels can synchronize the circadian clock of bumblebees (Bombus terrestris).

    Science.gov (United States)

    Chittka, Lars; Stelzer, Ralph J; Stanewsky, Ralf

    2013-05-01

    Endogenous circadian clocks are synchronized to the 24-h day by external zeitgebers such as daily light and temperature cycles. Bumblebee foragers show diurnal rhythms under daily light:dark cycles and short-period free-running circadian rhythms in constant light conditions in the laboratory. In contrast, during the continuous light conditions of the arctic summer, they show robust 24-h rhythms in their foraging patterns, meaning that some external zeitgeber must entrain their circadian clocks in the presence of constant light. Although the sun stays above the horizon for weeks during the arctic summer, the light quality, especially in the ultraviolet (UV) range, exhibits pronounced daily changes. Since the photoreceptors and photopigments that synchronize the circadian system of bees are not known, we tested if the circadian clocks of bumblebees (Bombus terrestris) can be entrained by daily cycles in UV light levels. Bumblebee colonies were set up in the laboratory and exposed to 12 h:12 h UV + :UV- cycles in otherwise continuous lighting conditions by placing UV filters on their foraging arenas for 12 h each day. The activity patterns of individual bees were recorded using fully automatic radiofrequency identification (RFID). We found that colonies manipulated in such a way showed synchronized 24-h rhythms, whereas simultaneously tested control colonies with no variation in UV light levels showed free-running rhythms instead. The results of our study show that bumblebee circadian rhythms can indeed be synchronized by daily cycles in ambient light spectral composition.

  3. Molecular clock is involved in predictive circadian adjustment of renal function.

    Science.gov (United States)

    Zuber, Annie Mercier; Centeno, Gabriel; Pradervand, Sylvain; Nikolaeva, Svetlana; Maquelin, Lionel; Cardinaux, Léonard; Bonny, Olivier; Firsov, Dmitri

    2009-09-22

    Renal excretion of water and major electrolytes exhibits a significant circadian rhythm. This functional periodicity is believed to result, at least in part, from circadian changes in secretion/reabsorption capacities of the distal nephron and collecting ducts. Here, we studied the molecular mechanisms underlying circadian rhythms in the distal nephron segments, i.e., distal convoluted tubule (DCT) and connecting tubule (CNT) and the cortical collecting duct (CCD). Temporal expression analysis performed on microdissected mouse DCT/CNT or CCD revealed a marked circadian rhythmicity in the expression of a large number of genes crucially involved in various homeostatic functions of the kidney. This analysis also revealed that both DCT/CNT and CCD possess an intrinsic circadian timing system characterized by robust oscillations in the expression of circadian core clock genes (clock, bma11, npas2, per, cry, nr1d1) and clock-controlled Par bZip transcriptional factors dbp, hlf, and tef. The clock knockout mice or mice devoid of dbp/hlf/tef (triple knockout) exhibit significant changes in renal expression of several key regulators of water or sodium balance (vasopressin V2 receptor, aquaporin-2, aquaporin-4, alphaENaC). Functionally, the loss of clock leads to a complex phenotype characterized by partial diabetes insipidus, dysregulation of sodium excretion rhythms, and a significant decrease in blood pressure. Collectively, this study uncovers a major role of molecular clock in renal function.

  4. Effect of circadian phase on memory acquisition and recall: operant conditioning vs. classical conditioning.

    Directory of Open Access Journals (Sweden)

    Madeleine V Garren

    Full Text Available There have been several studies on the role of circadian clocks in the regulation of associative learning and memory processes in both vertebrate and invertebrate species. The results have been quite variable and at present it is unclear to what extent the variability observed reflects species differences or differences in methodology. Previous results have shown that following differential classical conditioning in the cockroach, Rhyparobia maderae, in an olfactory discrimination task, formation of the short-term and long-term memory is under strict circadian control. In contrast, there appeared to be no circadian regulation of the ability to recall established memories. In the present study, we show that following operant conditioning of the same species in a very similar olfactory discrimination task, there is no impact of the circadian system on either short-term or long-term memory formation. On the other hand, ability to recall established memories is strongly tied to the circadian phase of training. On the basis of these data and those previously reported for phylogenetically diverse species, it is suggested that there may be fundamental differences in the way the circadian system regulates learning and memory in classical and operant conditioning.

  5. Circadian waves of expression of the APRR1/TOC1 family of pseudo-response regulators in Arabidopsis thaliana: insight into the plant circadian clock.

    Science.gov (United States)

    Matsushika, A; Makino, S; Kojima, M; Mizuno, T

    2000-09-01

    The Arabidopsis pseudo-response regulator, APRR1, has a unique structural design containing a pseudo-receiver domain and a C-terminal CONSTANS motif. This protein was originally characterized as a presumed component of the His-to-Asp phosphorelay systems in Arabidopsis thaliana. Recently, it was reported that APRR1 is identical to the TOC1 gene product, a mutational lesion of which affects the periods of many circadian rhythms in Arabidopsis plants. TOC1 is believed to be a component of the presumed circadian clock (or central oscillator). Based on these facts, in this study four more genes, each encoding a member of the APRR1/TOC1 family of pseudo-response regulators were identified and characterized with special reference to circadian rhythms. It was found that all these members of the APRR1/TOC1 family (APRR1, APRR3, APRR5, APRR7, and APRR9) are subjected to a circadian rhythm at the level of transcription. Furthermore, in a given 24 h period, the APRR-mRNAs started accumulating sequentially after dawn with 2-3 h intervals in the order of APRR9-->APRR7-->APRR5-->APRR3-->APRR1. These sequential events of transcription, termed 'circadian waves of APRR1/TOCI', were not significantly affected by the photoperiod conditions, if any (e.g. both long and short days), and the expression of APRR9 was first boosted always after dawn. Among these APRRs, in fact, only the expression of APRR9 was rapidly and transiently induced also by white light, whereas such light responses of others were very dull, if any. These results collectively support the view that these members of the APRR1/TOC1 family are together all involved in an as yet unknown mechanism underlying the Arabidopsis circadian clock. Here we propose that the circadian waves of the APRR1/TOC1 family members are most likely a molecular basis of such a biological clock in higher plants.

  6. Circadian Rhythms in Diet-Induced Obesity.

    Science.gov (United States)

    Engin, Atilla

    2017-01-01

    The biological clocks of the circadian timing system coordinate cellular and physiological processes and synchronizes these with daily cycles, feeding patterns also regulates circadian clocks. The clock genes and adipocytokines show circadian rhythmicity. Dysfunction of these genes are involved in the alteration of these adipokines during the development of obesity. Food availability promotes the stimuli associated with food intake which is a circadian oscillator outside of the suprachiasmatic nucleus (SCN). Its circadian rhythm is arranged with the predictable daily mealtimes. Food anticipatory activity is mediated by a self-sustained circadian timing and its principal component is food entrained oscillator. However, the hypothalamus has a crucial role in the regulation of energy balance rather than food intake. Fatty acids or their metabolites can modulate neuronal activity by brain nutrient-sensing neurons involved in the regulation of energy and glucose homeostasis. The timing of three-meal schedules indicates close association with the plasma levels of insulin and preceding food availability. Desynchronization between the central and peripheral clocks by altered timing of food intake and diet composition can lead to uncoupling of peripheral clocks from the central pacemaker and to the development of metabolic disorders. Metabolic dysfunction is associated with circadian disturbances at both central and peripheral levels and, eventual disruption of circadian clock functioning can lead to obesity. While CLOCK expression levels are increased with high fat diet-induced obesity, peroxisome proliferator-activated receptor (PPAR) alpha increases the transcriptional level of brain and muscle ARNT-like 1 (BMAL1) in obese subjects. Consequently, disruption of clock genes results in dyslipidemia, insulin resistance and obesity. Modifying the time of feeding alone can greatly affect body weight. Changes in the circadian clock are associated with temporal alterations in

  7. Circadian rhythms synchronize mitosis in Neurospora crassa.

    Science.gov (United States)

    Hong, Christian I; Zámborszky, Judit; Baek, Mokryun; Labiscsak, Laszlo; Ju, Kyungsu; Lee, Hyeyeong; Larrondo, Luis F; Goity, Alejandra; Chong, Hin Siong; Belden, William J; Csikász-Nagy, Attila

    2014-01-28

    The cell cycle and the circadian clock communicate with each other, resulting in circadian-gated cell division cycles. Alterations in this network may lead to diseases such as cancer. Therefore, it is critical to identify molecular components that connect these two oscillators. However, molecular mechanisms between the clock and the cell cycle remain largely unknown. A model filamentous fungus, Neurospora crassa, is a multinucleate system used to elucidate molecular mechanisms of circadian rhythms, but not used to investigate the molecular coupling between these two oscillators. In this report, we show that a conserved coupling between the circadian clock and the cell cycle exists via serine/threonine protein kinase-29 (STK-29), the Neurospora homolog of mammalian WEE1 kinase. Based on this finding, we established a mathematical model that predicts circadian oscillations of cell cycle components and circadian clock-dependent synchronized nuclear divisions. We experimentally demonstrate that G1 and G2 cyclins, CLN-1 and CLB-1, respectively, oscillate in a circadian manner with bioluminescence reporters. The oscillations of clb-1 and stk-29 gene expression are abolished in a circadian arrhythmic frq(ko) mutant. Additionally, we show the light-induced phase shifts of a core circadian component, frq, as well as the gene expression of the cell cycle components clb-1 and stk-29, which may alter the timing of divisions. We then used a histone hH1-GFP reporter to observe nuclear divisions over time, and show that a large number of nuclear divisions occur in the evening. Our findings demonstrate the circadian clock-dependent molecular dynamics of cell cycle components that result in synchronized nuclear divisions in Neurospora.

  8. [Effects of heavy machinery operation on the structural characters of cultivated soils in black soil region of Northeast China].

    Science.gov (United States)

    Wang, En-Heng; Chai, Ya-Fan; Chen, Xiang-Wei

    2008-02-01

    With the cultivated soils in black soil region of Northeast China as test objects, this paper measured their structural characters such as soil strength, bulk density, and non-capillary porosity/capillary porosity (NCP/CP) ratio before and after heavy and medium-sized machinery operation, aimed to study the effects of machinery operation on the physical properties of test soils. The results showed that after machinery operation, there existed three distinct layers from top to bottom in the soil profiles, i.e., plowed layer, cumulative compacted layer, and non-affected layer, according to the changes of soil strength. Under medium-sized machinery operation, these three layers were shallower, and there was a new plow pan at the depth between 17.5 and 30 cm. Heavy machinery operation had significant positive effects on the improvement of topsoil structure (P machinery, the bulk density of topsoil decreased by 7.2% and 3.5%, respectively, and NCP/CP increased by 556.6% after subsoiling, which would benefit water infiltration, reinforce water storage, and weaken the threat of soil erosion. The main action of heavy machinery operation was soil loosening, while that of medium-sized machinery operation was soil compacting.

  9. Regulated DNA Methylation and the Circadian Clock: Implications in Cancer

    Directory of Open Access Journals (Sweden)

    Tammy M. Joska

    2014-09-01

    Full Text Available Since the cloning and discovery of DNA methyltransferases (DNMT, there has been a growing interest in DNA methylation, its role as an epigenetic modification, how it is established and removed, along with the implications in development and disease. In recent years, it has become evident that dynamic DNA methylation accompanies the circadian clock and is found at clock genes in Neurospora, mice and cancer cells. The relationship among the circadian clock, cancer and DNA methylation at clock genes suggests a correlative indication that improper DNA methylation may influence clock gene expression, contributing to the etiology of cancer. The molecular mechanism underlying DNA methylation at clock loci is best studied in the filamentous fungi, Neurospora crassa, and recent data indicate a mechanism analogous to the RNA-dependent DNA methylation (RdDM or RNAi-mediated facultative heterochromatin. Although it is still unclear, DNA methylation at clock genes may function as a terminal modification that serves to prevent the regulated removal of histone modifications. In this capacity, aberrant DNA methylation may serve as a readout of misregulated clock genes and not as the causative agent. This review explores the implications of DNA methylation at clock loci and describes what is currently known regarding the molecular mechanism underlying DNA methylation at circadian clock genes.

  10. Entrainment of circadian rhythm by ambient temperature cycles in mice.

    Science.gov (United States)

    Refinetti, Roberto

    2010-08-01

    Much is known about how environmental light-dark cycles synchronize circadian rhythms in animals. The ability of environmental cycles of ambient temperature to synchronize circadian rhythms has also been investigated extensively but mostly in ectotherms. In the present study, the synchronization of the circadian rhythm of running-wheel activity by environmental cycles of ambient temperature was studied in laboratory mice. Although all mice were successfully entrained by a light-dark cycle, only 60% to 80% of the mice were entrained by temperature cycles (24-32 degrees C or 24-12 degrees C), and attainment of stable entrainment seemed to take longer under temperature cycles than under a light-dark cycle. This suggests that ambient temperature cycles are weaker zeitgebers than light-dark cycles, which is consistent with the results of the few previous studies using mammalian species. Whereas 80% of the mice were entrained by 24-h temperature cycles, only 60% were entrained by 23-h cycles, and none was entrained by 25-h cycles. The results did not clarify whether entrainment by temperature cycles is caused directly by temperature or indirectly through a temperature effect on locomotor activity, but it is clear that the rhythm of running-wheel activity in mice can be entrained by ambient temperature cycles in the nonnoxious range.

  11. Cryptochrome mediates light-dependent magnetosensitivity of Drosophila's circadian clock.

    Directory of Open Access Journals (Sweden)

    Taishi Yoshii

    2009-04-01

    Full Text Available Since 1960, magnetic fields have been discussed as Zeitgebers for circadian clocks, but the mechanism by which clocks perceive and process magnetic information has remained unknown. Recently, the radical-pair model involving light-activated photoreceptors as magnetic field sensors has gained considerable support, and the blue-light photoreceptor cryptochrome (CRY has been proposed as a suitable molecule to mediate such magnetosensitivity. Since CRY is expressed in the circadian clock neurons and acts as a critical photoreceptor of Drosophila's clock, we aimed to test the role of CRY in magnetosensitivity of the circadian clock. In response to light, CRY causes slowing of the clock, ultimately leading to arrhythmic behavior. We expected that in the presence of applied magnetic fields, the impact of CRY on clock rhythmicity should be altered. Furthermore, according to the radical-pair hypothesis this response should be dependent on wavelength and on the field strength applied. We tested the effect of applied static magnetic fields on the circadian clock and found that flies exposed to these fields indeed showed enhanced slowing of clock rhythms. This effect was maximal at 300 muT, and reduced at both higher and lower field strengths. Clock response to magnetic fields was present in blue light, but absent under red-light illumination, which does not activate CRY. Furthermore, cry(b and cry(OUT mutants did not show any response, and flies overexpressing CRY in the clock neurons exhibited an enhanced response to the field. We conclude that Drosophila's circadian clock is sensitive to magnetic fields and that this sensitivity depends on light activation of CRY and on the applied field strength, consistent with the radical pair mechanism. CRY is widespread throughout biological systems and has been suggested as receptor for magnetic compass orientation in migratory birds. The present data establish the circadian clock of Drosophila as a model system

  12. Circadian profiles in the embryonic chick heart: L-type voltage-gated calcium channels and signaling pathways.

    Science.gov (United States)

    Ko, Michael L; Shi, Liheng; Grushin, Kirill; Nigussie, Fikru; Ko, Gladys Y-P

    2010-10-01

    Circadian clocks exist in the heart tissue and modulate multiple physiological events, from cardiac metabolism to contractile function and expression of circadian oscillator and metabolic-related genes. Ample evidence has demonstrated that there are endogenous circadian oscillators in adult mammalian cardiomyocytes. However, mammalian embryos cannot be entrained independently to light-dark (LD) cycles in vivo without any maternal influence, but circadian genes are well expressed and able to oscillate in embryonic stages. The authors took advantage of using chick embryos that are independent of maternal influences to investigate whether embryonic hearts could be entrained under LD cycles in ovo. The authors found circadian regulation of L-type voltage-gated calcium channels (L-VGCCs), the ion channels responsible for the production of cardiac muscle contraction in embryonic chick hearts. The mRNA levels and protein expression of VGCCα1C and VGCCα1D are under circadian control, and the average L-VGCC current density is significantly larger when cardiomyocytes are recorded during the night than day. The phosphorylation states of several kinases involved in insulin signaling and cardiac metabolism, including extracellular signal-regulated kinase (Erk), stress-activated protein kinase (p38), protein kinase B (Akt), and glycogen synthase kinase-3β (GSK-3β), are also under circadian control. Both Erk and p38 have been implicated in regulating cardiac contractility and in the development of various pathological states, such as cardiac hypertrophy and heart failure. Even though both Erk and phosphoinositide 3-kinase (PI3K)-Akt signaling pathways participate in complex cellular processes regarding physiological or pathological states of cardiomyocytes, the circadian oscillators in the heart regulate these pathways independently, and both pathways contribute to the circadian regulation of L-VGCCs.

  13. [Circadian markers and genes in bipolar disorder].

    Science.gov (United States)

    Yeim, S; Boudebesse, C; Etain, B; Belliviera, F

    2015-09-01

    Bipolar disorder is a severe and complex multifactorial disease, characterized by alternance of acute episodes of depression and mania/hypomania, interspaced by euthymic periods. The etiological determinants of bipolar disorder yet, are still poorly understood. For the last 30 years, chronobiology is an important field of investigation to better understand the pathophysiology of bipolar disorder. We conducted a review using Medline, ISI Database, EMBase, PsyInfo up to January 2015, using the following keywords combinations: "mood disorder", "bipolar disorder", "depression", "unipolar disorder", "major depressive disorder", "affective disorder", for psychiatric conditions; and "circadian rhythms", "circadian markers", "circadian gene", "clock gene", "melatonin" for circadian rhythms. The search critera was presence of word in any field of the article. Quantitative and qualitative circadian abnormalities are associated with bipolar disorders both during acute episodes and euthymic periods, suggesting that these altered circadian rhythms may represent biological trait markers of the disorder. These circadian dysfunctions were assessed by various validated tools including polysomnography, actigraphy, sleep diaries, chronotype assessments and blood melatonin/cortisol measures. Other altered endogenous circadian activities have also been reported in bipolar patients, such as hormones secretion, core body temperature or fibroblasts activity. Moreover, these markers were also altered in healthy relatives of bipolar patients, suggesting a degree of heritability. Several genetic association studies have also showed associations between multiple circadian genes and bipolar disorder, such as CLOCK, ARTNL1, GSK3β, PER3, NPAS2, NR1D1, TIMELESS, RORA, RORB, and CSNK1ε. Thus, these circadian gene variants may contribute to the genetic susceptibility of the disease. Furthermore, the study of the clock system may help to better understand some phenotypic aspects like the

  14. Synchronous circadian voltage rhythms with asynchronous calcium rhythms in the suprachiasmatic nucleus.

    Science.gov (United States)

    Enoki, Ryosuke; Oda, Yoshiaki; Mieda, Michihiro; Ono, Daisuke; Honma, Sato; Honma, Ken-Ichi

    2017-03-07

    The suprachiasmatic nucleus (SCN), the master circadian clock, contains a network composed of multiple types of neurons which are thought to form a hierarchical and multioscillator system. The molecular clock machinery in SCN neurons drives membrane excitability and sends time cue signals to various brain regions and peripheral organs. However, how and at what time of the day these neurons transmit output signals remain largely unknown. Here, we successfully visualized circadian voltage rhythms optically for many days using a genetically encoded voltage sensor, ArcLightD. Unexpectedly, the voltage rhythms are synchronized across the entire SCN network of cultured slices, whereas simultaneously recorded Ca(2+) rhythms are topologically specific to the dorsal and ventral regions. We further found that the temporal order of these two rhythms is cell-type specific: The Ca(2+) rhythms phase-lead the voltage rhythms in AVP neurons but Ca(2+) and voltage rhythms are nearly in phase in VIP neurons. We confirmed that circadian firing rhythms are also synchronous and are coupled with the voltage rhythms. These results indicate that SCN networks with asynchronous Ca(2+) rhythms produce coherent voltage rhythms.

  15. Alternative Splicing Mediates Responses of the Arabidopsis Circadian Clock to Temperature Changes[W

    Science.gov (United States)

    James, Allan B.; Syed, Naeem Hasan; Bordage, Simon; Marshall, Jacqueline; Nimmo, Gillian A.; Jenkins, Gareth I.; Herzyk, Pawel; Brown, John W.S.; Nimmo, Hugh G.

    2012-01-01

    Alternative splicing plays crucial roles by influencing the diversity of the transcriptome and proteome and regulating protein structure/function and gene expression. It is widespread in plants, and alteration of the levels of splicing factors leads to a wide variety of growth and developmental phenotypes. The circadian clock is a complex piece of cellular machinery that can regulate physiology and behavior to anticipate predictable environmental changes on a revolving planet. We have performed a system-wide analysis of alternative splicing in clock components in Arabidopsis thaliana plants acclimated to different steady state temperatures or undergoing temperature transitions. This revealed extensive alternative splicing in clock genes and dynamic changes in alternatively spliced transcripts. Several of these changes, notably those affecting the circadian clock genes LATE ELONGATED HYPOCOTYL (LHY) and PSEUDO RESPONSE REGULATOR7, are temperature-dependent and contribute markedly to functionally important changes in clock gene expression in temperature transitions by producing nonfunctional transcripts and/or inducing nonsense-mediated decay. Temperature effects on alternative splicing contribute to a decline in LHY transcript abundance on cooling, but LHY promoter strength is not affected. We propose that temperature-associated alternative splicing is an additional mechanism involved in the operation and regulation of the plant circadian clock. PMID:22408072

  16. Weakly circadian cells improve resynchrony.

    Directory of Open Access Journals (Sweden)

    Alexis B Webb

    Full Text Available The mammalian suprachiasmatic nuclei (SCN contain thousands of neurons capable of generating near 24-h rhythms. When isolated from their network, SCN neurons exhibit a range of oscillatory phenotypes: sustained or damping oscillations, or arrhythmic patterns. The implications of this variability are unknown. Experimentally, we found that cells within SCN explants recover from pharmacologically-induced desynchrony by re-establishing rhythmicity and synchrony in waves, independent of their intrinsic circadian period We therefore hypothesized that a cell's location within the network may also critically determine its resynchronization. To test this, we employed a deterministic, mechanistic model of circadian oscillators where we could independently control cell-intrinsic and network-connectivity parameters. We found that small changes in key parameters produced the full range of oscillatory phenotypes seen in biological cells, including similar distributions of period, amplitude and ability to cycle. The model also predicted that weaker oscillators could adjust their phase more readily than stronger oscillators. Using these model cells we explored potential biological consequences of their number and placement within the network. We found that the population synchronized to a higher degree when weak oscillators were at highly connected nodes within the network. A mathematically independent phase-amplitude model reproduced these findings. Thus, small differences in cell-intrinsic parameters contribute to large changes in the oscillatory ability of a cell, but the location of weak oscillators within the network also critically shapes the degree of synchronization for the population.

  17. Circadian clock proteins and immunity.

    Science.gov (United States)

    Curtis, Anne M; Bellet, Marina M; Sassone-Corsi, Paolo; O'Neill, Luke A J

    2014-02-20

    Immune parameters change with time of day and disruption of circadian rhythms has been linked to inflammatory pathologies. A circadian-clock-controlled immune system might allow an organism to anticipate daily changes in activity and feeding and the associated risk of infection or tissue damage to the host. Responses to bacteria have been shown to vary depending on time of infection, with mice being more at risk of sepsis when challenged ahead of their activity phase. Studies highlight the extent to which the molecular clock, most notably the core clock proteins BMAL1, CLOCK, and REV-ERBα, control fundamental aspects of the immune response. Examples include the BMAL1:CLOCK heterodimer regulating toll-like receptor 9 (TLR9) expression and repressing expression of the inflammatory monocyte chemokine ligand (CCL2) as well as REV-ERBα suppressing the induction of interleukin-6. Understanding the daily rhythm of the immune system could have implications for vaccinations and how we manage infectious and inflammatory diseases. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Evolutionary Endocrinology of Hormonal Rhythms: Juvenile Hormone Titer Circadian Polymorphism in Gryllus firmus.

    Science.gov (United States)

    Zera, Anthony J

    2016-08-01

    Daily rhythms for hormonal traits are likely widespread and important aspects of organismal (e.g., life history) adaptation. Yet they remain substantially understudied, especially with respect to variable rhythms within species. The cricket, Gryllus firmus, exhibits a genetically polymorphic circadian rhythm for the blood titer of the key hormone, juvenile hormone (JH). Gryllus firmus is also wing-polymorphic, consisting of a dispersing morph that delays reproduction and a flightless morph with substantially enhanced egg production. JH circadian phenotype strongly covaries with morph type: The blood JH titer is strongly rhythmic in multiple populations artificially-selected for the dispersing morph (LW(f) = long wings with functional flight muscles) and is essentially arrhythmic in populations selected for the SW (short-winged) morph. Association between JH titer cycle and LW(f) morph is also found in natural populations of G. firmus and in several related species in the field. This is one of the very few studies of endocrine titer variation in natural populations of an insect. The morph-specific cycle is underlain by a circadian rhythm in hormone biosynthesis, which in turn is underlain by a rhythm in a brain neuropeptide regulator of JH biosynthesis. The morph-specific JH titer circadian cycle is also strongly correlated with a morph-specific daily rhythm in global gene expression. This is currently the only example of a genetically-variable hormone circadian rhythm in both the laboratory and field that is strongly associated with an ecologically important polymorphism. The extensive information on the underlying causes of the morph-specific JH titer rhythm, coupled with the strong association between the JH circadian rhythm and wing polymorphism makes this system in G. firmus an exceptional experimental model to investigate the mechanisms underlying circadian hormonal adaptations. Genetic polymorphism for the JH titer circadian rhythm in G. firmus is discussed

  19. Present Situation of Petroleum Machinery Manufacturers in China

    Institute of Scientific and Technical Information of China (English)

    Li Xilu

    2008-01-01

    Since China joined the WTO, the environment for the development of petroleum machinery industry in the country has changed a lot. As international petroleum machinery manufacturers enter into Chinese market, petroleum machinery manufacturers of the country are facing fierce competition both at home and abroad.

  20. 30 CFR 56.14205 - Machinery, equipment, and tools.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Machinery, equipment, and tools. 56.14205... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-SURFACE METAL AND NONMETAL MINES Machinery and Equipment Safety Practices and Operational Procedures § 56.14205 Machinery, equipment, and tools....

  1. 46 CFR 58.01-20 - Machinery guards.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Machinery guards. 58.01-20 Section 58.01-20 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MAIN AND AUXILIARY MACHINERY AND RELATED SYSTEMS General Requirements § 58.01-20 Machinery guards. Gears, couplings, flywheels...

  2. 46 CFR 109.205 - Inspection of boilers and machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Inspection of boilers and machinery. 109.205 Section 109... OPERATIONS Tests, Drills, and Inspections § 109.205 Inspection of boilers and machinery. The chief engineer or engineer in charge, before he assumes charge of the boilers and machinery of a unit shall...

  3. 29 CFR 1915.165 - Ship's deck machinery.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Ship's deck machinery. 1915.165 Section 1915.165 Labor... (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Ship's Machinery and Piping Systems § 1915.165 Ship's deck machinery. (a) Before work is performed on the anchor windlass or any...

  4. 46 CFR 122.208 - Accidents to machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Accidents to machinery. 122.208 Section 122.208 Shipping... Voyage Records § 122.208 Accidents to machinery. The owner, managing operator, or master shall report damage to a boiler, unfired pressure vessel, or machinery that renders further use of the item...

  5. 29 CFR 1915.164 - Ship's propulsion machinery.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Ship's propulsion machinery. 1915.164 Section 1915.164 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION... Machinery and Piping Systems § 1915.164 Ship's propulsion machinery. (a) Before work is performed on...

  6. 46 CFR 109.419 - Report of unsafe machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Report of unsafe machinery. 109.419 Section 109.419... OPERATIONS Reports, Notifications, and Records Reports and Notifications § 109.419 Report of unsafe machinery. If a boiler, unfired pressure vessel, or other machinery on a unit is unsafe to operate, the...

  7. 30 CFR 57.14205 - Machinery, equipment, and tools.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Machinery, equipment, and tools. 57.14205... NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Machinery and Equipment Safety Practices and Operational Procedures § 57.14205 Machinery, equipment, and...

  8. 46 CFR 252.33 - Hull and machinery insurance.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 8 2010-10-01 2010-10-01 false Hull and machinery insurance. 252.33 Section 252.33... Subsidy Rates § 252.33 Hull and machinery insurance. (a) Subsidy items. The fair and reasonable net premium costs (including stamp taxes) of hull and machinery, increased value, excess general...

  9. 29 CFR 1910.214 - Cooperage machinery. [Reserved

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 5 2010-07-01 2010-07-01 false Cooperage machinery. 1910.214 Section 1910.214 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR OCCUPATIONAL SAFETY AND HEALTH STANDARDS Machinery and Machine Guarding § 1910.214 Cooperage machinery....

  10. 46 CFR 196.30-5 - Accidents to machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Accidents to machinery. 196.30-5 Section 196.30-5... Reports of Accidents, Repairs, and Unsafe Equipment § 196.30-5 Accidents to machinery. (a) In the event of an accident to a boiler, unfired pressure vessel, or machinery tending to render the further use...

  11. 46 CFR 97.30-5 - Accidents to machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Accidents to machinery. 97.30-5 Section 97.30-5 Shipping... Reports of Accidents, Repairs, and Unsafe Equipment § 97.30-5 Accidents to machinery. (a) In the event of an accident to a boiler, unfired pressure vessel, or machinery tending to render the further use...

  12. 46 CFR 185.208 - Accidents to machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Accidents to machinery. 185.208 Section 185.208 Shipping...) OPERATIONS Marine Casualties and Voyage Records § 185.208 Accidents to machinery. The owner, managing operator, or master shall report damage to a boiler, unfired pressure vessel, or machinery that...

  13. 46 CFR 78.33-5 - Accidents to machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Accidents to machinery. 78.33-5 Section 78.33-5 Shipping... Accidents, Repairs, and Unsafe Equipment § 78.33-5 Accidents to machinery. (a) In the event of an accident to a boiler, unfired pressure vessel, or machinery tending to render the further use of the...

  14. 46 CFR 185.352 - Ventilation of gasoline machinery spaces.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Ventilation of gasoline machinery spaces. 185.352 Section 185.352 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS... machinery spaces. The mechanical exhaust for the ventilation of a gasoline machinery space, required...

  15. 46 CFR 130.460 - Placement of machinery alarms.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Placement of machinery alarms. 130.460 Section 130.460..., AND MISCELLANEOUS EQUIPMENT AND SYSTEMS Automation of Unattended Machinery Spaces § 130.460 Placement of machinery alarms. (a) Visible and audible alarms must be installed at the pilothouse to...

  16. 46 CFR 171.095 - Machinery space bulkhead.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Machinery space bulkhead. 171.095 Section 171.095... PERTAINING TO VESSELS CARRYING PASSENGERS Additional Subdivision Requirements § 171.095 Machinery space... transverse watertight bulkheads to separate the machinery space from the remainder of the vessel....

  17. 46 CFR 111.103-3 - Machinery space ventilation.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Machinery space ventilation. 111.103-3 Section 111.103-3...-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-3 Machinery space ventilation. (a) Each machinery space ventilation system must have two controls to stop the ventilation, one of which may be the...

  18. 33 CFR 157.39 - Machinery space bilges.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Machinery space bilges. 157.39... Vessel Operation § 157.39 Machinery space bilges. (a) A tank vessel may discharge an oily mixture from a machinery space bilge that is combined with an oil cargo residue if the vessel discharges in compliance...

  19. Circadian Clocks in the Immune System.

    Science.gov (United States)

    Labrecque, Nathalie; Cermakian, Nicolas

    2015-08-01

    The immune system is a complex set of physiological mechanisms whose general aim is to defend the organism against non-self-bodies, such as pathogens (bacteria, viruses, parasites), as well as cancer cells. Circadian rhythms are endogenous 24-h variations found in virtually all physiological processes. These circadian rhythms are generated by circadian clocks, located in most cell types, including cells of the immune system. This review presents an overview of the clocks in the immune system and of the circadian regulation of the function of immune cells. Most immune cells express circadian clock genes and present a wide array of genes expressed with a 24-h rhythm. This has profound impacts on cellular functions, including a daily rhythm in the synthesis and release of cytokines, chemokines and cytolytic factors, the daily gating of the response occurring through pattern recognition receptors, circadian rhythms of cellular functions such as phagocytosis, migration to inflamed or infected tissue, cytolytic activity, and proliferative response to antigens. Consequently, alterations of circadian rhythms (e.g., clock gene mutation in mice or environmental disruption similar to shift work) lead to disturbed immune responses. We discuss the implications of these data for human health and the areas that future research should aim to address.

  20. OPTIMAL MAINTENANCE AND REPLACEMENT OF EXTRACTION MACHINERY

    Institute of Scientific and Technical Information of China (English)

    Suresh P.SETHI; Hong-Mo YEH; Rong ZHANG; Andrew K.S.JARDINE

    2008-01-01

    This paper considers a problem of optimal preventive maintenance and replacement schedule ofequipment devoted to extracting resources from known deposits. Typical examples are oil drills, mine shovels, etc. At most one replacement of the existing machinery by a new one is allowed. The problem is formulated as an optimal control problem subject to the state constraint that the remaining deposit at any given time is nonnegative. We show that the optimal preventive maintenance, production rates, and the replacement and salvage times of the existing machinery and the new one, if required, can be obtained by solving sequentially a series of free-end-point optimal control problems. Moreover, an algorithm based on this result is developed and used to solve two illustrative examples.

  1. The Autophagic Machinery in Enterovirus Infection

    Directory of Open Access Journals (Sweden)

    Jeffrey K. F. Lai

    2016-01-01

    Full Text Available The Enterovirus genus of the Picornaviridae family comprises many important human pathogens, including polioviruses, rhinovirus, enterovirus A71, and enterovirus D68. They cause a wide variety of diseases, ranging from mild to severe life-threatening diseases. Currently, no effective vaccine is available against enteroviruses except for poliovirus. Enteroviruses subvert the autophagic machinery to benefit their assembly, maturation, and exit from host. Some enteroviruses spread between cells via a process described as autophagosome-mediated exit without lysis (AWOL. The early and late phases of autophagy are regulated through various lipids and their metabolizing enzymes. Some of these lipids and enzymes are specifically regulated by enteroviruses. In the present review, we summarize the current understanding of the regulation of autophagic machinery by enteroviruses, and provide updates on recent developments in this field.

  2. Temperature sensitivity of circadian clocks is conserved across Drosophila species melanogaster, malerkotliana and ananassae.

    Science.gov (United States)

    Prabhakaran, Priya M; Sheeba, Vasu

    2014-11-01

    Light and temperature are the major environmental cycles that can synchronize circadian rhythms in a variety of organisms. Previously, we have shown that under light/dark cycles of various photoperiods, the Drosophila species ananassae exhibits unimodal activity pattern with a prominent morning activity peak in contrast with Drosophila melanogaster and Drosophila malerkotliana, which show bimodal activity pattern with morning and evening activity peaks. Here we report that circadian clocks controlling activity/rest rhythm of these two less-studied species D. malerkotliana and D. ananassae can be synchronized by temperature cycles and that even under temperature cycles D. ananassae exhibits only a pronounced morning (thermophase onset) activity peak. Although D. melanogaster and D. ananassae exhibit differences in the phase of activity/rest rhythm under temperature cycles, circadian clocks of both show similar sensitivity to warm temperature pulses. Circadian period of activity/rest rhythm of D. ananassae differs from the other two species at some moderate-range temperatures; however, in conditions that are more extreme, circadian clocks of D. melanogaster, D. malerkotliana and D. ananassae appear to be largely temperature compensated.

  3. Machinery prognostics and prognosis oriented maintenance management

    CERN Document Server

    Yan, Jihong

    2014-01-01

    This book gives a complete presentatin of the basic essentials of machinery prognostics and prognosis oriented maintenance management, and takes a look at the cutting-edge discipline of intelligent failure prognosis technologies for condition-based maintenance.  Latest research results and application methods are introduced for signal processing, reliability moelling, deterioration evaluation, residual life prediction and maintenance-optimization as well as applications of these methods.

  4. Property Analysis of the Agricultural Machinery Lubricants

    Directory of Open Access Journals (Sweden)

    Tone Ploj

    2000-03-01

    Full Text Available We need to produce enough healthy and cheap food as well as to preserve the ecologic equilibrium. This can be achived by using modern machinery and up- to-date knowledge and technology. Agricultural machinery, in which 40-60% of all funds are invested, is poorly maintained and underused. The main causes for this are poor knowledge and extensive farm land fragmentation. The fact that over 140,000 tractors in Slovenia are on average 9.6 years old, i.e. that more than 80% of overall agricultural machinery is obsolete, should be a matter of serious concern. In the paper we follow tribological conditions in particular tractor assemblies. In the first part of the paper we have treated the required conditions of tractor manufacturers in Europe and primarily in Slovenia, what has served us in the final phase of the research for elaboration of the model. In this way we have got data about the presence of particular tractor types. We have separately elaborated the necessary specifications of engine lubricants, transmission, gears, hydraulics and wet breaks. We have carried out chemical and mechanical analyses of all accessible lubricants in agricultural mechanisation. The results of the new oils were coordinated with the required specifications of tractor manufacturers and so we have got such a model, that certainly meet all lubricating requirements of our tractors.

  5. The exportomer: the peroxisomal receptor export machinery.

    Science.gov (United States)

    Platta, Harald W; Hagen, Stefanie; Erdmann, Ralf

    2013-04-01

    Peroxisomes constitute a dynamic compartment of almost all eukaryotic cells. Depending on environmental changes and cellular demands peroxisomes can acquire diverse metabolic roles. The compartmentalization of peroxisomal matrix enzymes is a prerequisite to carry out their physiologic function. The matrix proteins are synthesized on free ribosomes in the cytosol and are ferried to the peroxisomal membrane by specific soluble receptors. Subsequent to cargo release into the peroxisomal matrix, the receptors are exported back to the cytosol to facilitate further rounds of matrix protein import. This dislocation step is accomplished by a remarkable machinery, which comprises enzymes required for the ubiquitination as well as the ATP-dependent extraction of the receptor from the membrane. Interestingly, receptor ubiquitination and dislocation are the only known energy-dependent steps in the peroxisomal matrix protein import process. The current view is that the export machinery of the receptors might function as molecular motor not only in the dislocation of the receptors but also in the import step of peroxisomal matrix protein by coupling ATP-dependent removal of the peroxisomal import receptor with cargo translocation into the organelle. In this review we will focus on the architecture and function of the peroxisomal receptor export machinery, the peroxisomal exportomer.

  6. Expression conservation within the circadian clock of a monocot: natural variation at barley Ppd-H1 affects circadian expression of flowering time genes, but not clock orthologs

    Directory of Open Access Journals (Sweden)

    Campoli Chiara

    2012-06-01

    Full Text Available Abstract Background The circadian clock is an endogenous mechanism that coordinates biological processes with daily changes in the environment. In plants, circadian rhythms contribute to both agricultural productivity and evolutionary fitness. In barley, the photoperiod response regulator and flowering-time gene Ppd-H1 is orthologous to the Arabidopsis core-clock gene PRR7. However, relatively little is known about the role of Ppd-H1 and other components of the circadian clock in temperate crop species. In this study, we identified barley clock orthologs and tested the effects of natural genetic variation at Ppd-H1 on diurnal and circadian expression of clock and output genes from the photoperiod-response pathway. Results Barley clock orthologs HvCCA1, HvGI, HvPRR1, HvPRR37 (Ppd-H1, HvPRR73, HvPRR59 and HvPRR95 showed a high level of sequence similarity and conservation of diurnal and circadian expression patterns, when compared to Arabidopsis. The natural mutation at Ppd-H1 did not affect diurnal or circadian cycling of barley clock genes. However, the Ppd-H1 mutant was found to be arrhythmic under free-running conditions for the photoperiod-response genes HvCO1, HvCO2, and the MADS-box transcription factor and vernalization responsive gene Vrn-H1. Conclusion We suggest that the described eudicot clock is largely conserved in the monocot barley. However, genetic differentiation within gene families and differences in the function of Ppd-H1 suggest evolutionary modification in the angiosperm clock. Our data indicates that natural variation at Ppd-H1 does not affect the expression level of clock genes, but controls photoperiodic output genes. Circadian control of Vrn-H1 in barley suggests that this vernalization responsive gene is also controlled by the photoperiod-response pathway. Structural and functional characterization of the barley circadian clock will set the basis for future studies of the adaptive significance of the circadian clock in

  7. Expression conservation within the circadian clock of a monocot: natural variation at barley Ppd-H1 affects circadian expression of flowering time genes, but not clock orthologs.

    Science.gov (United States)

    Campoli, Chiara; Shtaya, Munqez; Davis, Seth J; von Korff, Maria

    2012-06-21

    The circadian clock is an endogenous mechanism that coordinates biological processes with daily changes in the environment. In plants, circadian rhythms contribute to both agricultural productivity and evolutionary fitness. In barley, the photoperiod response regulator and flowering-time gene Ppd-H1 is orthologous to the Arabidopsis core-clock gene PRR7. However, relatively little is known about the role of Ppd-H1 and other components of the circadian clock in temperate crop species. In this study, we identified barley clock orthologs and tested the effects of natural genetic variation at Ppd-H1 on diurnal and circadian expression of clock and output genes from the photoperiod-response pathway. Barley clock orthologs HvCCA1, HvGI, HvPRR1, HvPRR37 (Ppd-H1), HvPRR73, HvPRR59 and HvPRR95 showed a high level of sequence similarity and conservation of diurnal and circadian expression patterns, when compared to Arabidopsis. The natural mutation at Ppd-H1 did not affect diurnal or circadian cycling of barley clock genes. However, the Ppd-H1 mutant was found to be arrhythmic under free-running conditions for the photoperiod-response genes HvCO1, HvCO2, and the MADS-box transcription factor and vernalization responsive gene Vrn-H1. We suggest that the described eudicot clock is largely conserved in the monocot barley. However, genetic differentiation within gene families and differences in the function of Ppd-H1 suggest evolutionary modification in the angiosperm clock. Our data indicates that natural variation at Ppd-H1 does not affect the expression level of clock genes, but controls photoperiodic output genes. Circadian control of Vrn-H1 in barley suggests that this vernalization responsive gene is also controlled by the photoperiod-response pathway. Structural and functional characterization of the barley circadian clock will set the basis for future studies of the adaptive significance of the circadian clock in Triticeae species.

  8. Chronobesity: role of the circadian system in the obesity epidemic.

    Science.gov (United States)

    Laermans, J; Depoortere, I

    2016-02-01

    Although obesity is considered to result from an imbalance between energy uptake and energy expenditure, the strategy of dietary changes and physical exercise has failed to tackle the global obesity epidemic. In search of alternative and more adequate treatment options, research has aimed at further unravelling the mechanisms underlying this excessive weight gain. While numerous studies are focusing on the neuroendocrine alterations that occur after bariatric Roux-en-Y gastric bypass surgery, an increasing amount of chronobiological studies have started to raise awareness concerning the pivotal role of the circadian system in the development and exacerbation of obesity. This internal timekeeping mechanism rhythmically regulates metabolic and physiological processes in order to meet the fluctuating demands in energy use and supply throughout the 24-h day. This review elaborates on the extensive bidirectional interaction between the circadian system and metabolism and explains how disruption of body clocks by means of shift work, frequent time zone travelling or non-stop consumption of calorie-dense foods can evoke detrimental metabolic alterations that contribute to obesity. Altering the body's circadian rhythms by means of time-related dietary approaches (chrononutrition) or pharmacological substances (chronobiotics) may therefore represent a novel and interesting way to prevent or treat obesity and associated comorbidities.

  9. Circadian rhythms in electrical circuits of Clivia miniata.

    Science.gov (United States)

    Volkov, Alexander G; Wooten, Joseph D; Waite, Astian J; Brown, Corydon R; Markin, Vladislav S

    2011-10-15

    The biological clock regulates a wide range of physiological processes in plants. Here we show circadian variation of the Clivia miniata responses to electrical stimulation. The biologically closed electrochemical circuits in the leaves of C. miniata (Kaffir lily), which regulate its physiology, were analyzed in vivo using the charge stimulation method. The electrostimulation was provided with different voltages and electrical charges. Resistance between Ag/AgCl electrodes in the leaf of C. miniata was higher at night than during the day or the following day in the darkness. The biologically closed electrical circuits with voltage gated ion channels in C. miniata are activated the next day, even in the darkness. C. miniata memorizes daytime and nighttime. At continuous light, C. miniata recognizes nighttime and increases the input resistance to the nighttime value even under light. These results show that the circadian clock can be maintained endogenously and has electrochemical oscillators, which can activate voltage gated ion channels in biologically closed electrochemical circuits. The activation of voltage gated channels depends on the applied voltage, electrical charge and speed of transmission of electrical energy from the electrostimulator to the C. miniata leaves. We present the equivalent electrical circuits in C. miniata and its circadian variation to explain the experimental data.

  10. A stochastic model for circadian rhythms from coupled ultradian oscillators

    Directory of Open Access Journals (Sweden)

    Illner Reinhard

    2007-01-01

    Full Text Available Abstract Background Circadian rhythms with varying components exist in organisms ranging from humans to cyanobacteria. A simple evolutionarily plausible mechanism for the origin of such a variety of circadian oscillators, proposed in earlier work, involves the non-disruptive coupling of pre-existing ultradian transcriptional-translational oscillators (TTOs, producing "beats," in individual cells. However, like other TTO models of circadian rhythms, it is important to establish that the inherent stochasticity of the protein binding and unbinding does not invalidate the finding of clear oscillations with circadian period. Results The TTOs of our model are described in two versions: 1 a version in which the activation or inhibition of genes is regulated stochastically, where the 'unoccupied" (or "free" time of the site under consideration depends on the concentration of a protein complex produced by another site, and 2 a deterministic, "time-averaged" version in which the switching between the "free" and "occupied" states of the sites occurs so rapidly that the stochastic effects average out. The second case is proved to emerge from the first in a mathematically rigorous way. Numerical results for both scenarios are presented and compared. Conclusion Our model proves to be robust to the stochasticity of protein binding/unbinding at experimentally determined rates and even at rates several orders of magnitude slower. We have not only confirmed this by numerical simulation, but have shown in a mathematically rigorous way that the time-averaged deterministic system is indeed the fast-binding-rate limit of the full stochastic model.

  11. Crayfish Procambarus clarkii retina and nervous system exhibit antioxidant circadian rhythms coupled with metabolic and luminous daily cycles.

    Science.gov (United States)

    Fanjul-Moles, María Luisa; Prieto-Sagredo, Julio; López, Dario Santiago; Bartolo-Orozco, Ramón; Cruz-Rosas, Hugo

    2009-01-01

    Based on previous work in which we proposed midgut as a putative peripheral oscillator responsible for circadian reduced glutathione (GSH) crayfish status, herein we investigated the retina and optic lobe-brain (OL-B) circadian GSH system and its ability to deal with reactive oxygen species (ROS) produced as a consequence of metabolic rhythms and light variations. We characterized daily and antioxidant circadian variations of the different parameters of the glutathione system, including GSH, oxidized glutathione (GSSG), glutathione reductase (GR) and glutathione peroxidase (GPx), as well as metabolic and lipoperoxidative circadian oscillations in retina and OL-B, determining internal and external GSH-system synchrony. The results demonstrate statistically significant bi- and unimodal daily and circadian rhythms in all GSH-cycle parameters, substrates and enzymes in OL-B and retina, as well as an apparent direct effect of light on these rhythms, especially in the retina. The luminous condition appears to stimulate the GSH system to antagonize ROS and lipid peroxidation (LPO) daily and circadian rhythms occurring in both structures, oscillating with higher LPO under dark conditions. We suggest that the difference in the effect of light on GSH rhythmic mechanisms of both structures for antagonizing ROS could be due to differences in glutathione-system coupling strength with the circadian clock.

  12. ON NECESSITY FOR CREATION OF TECHNOLOGICAL MACHINERY SYSTEM IN CONSTRUCTION COMPLEX

    Directory of Open Access Journals (Sweden)

    A. V. Vavilov

    2014-01-01

    Full Text Available The paper substantiates the necessity for creation of a technological machinery system in multi-industry construction complex that is from development of raw material resources and production of construction materials (logging and mining industry, woodworking, production of crushed stone, cement, concrete etc. to construction of actual 3D and plate objects. Attention has been attracted to continuous renovation of construction technologies and emergence of new construction materials that requires corresponding technical facilities for their efficient application and creation of these facilities is lagging behind under existing conditions. Such approach leads to saturation of the Republican machinery park by import equipment and technology that correspond to introduced technologies and construction materials according to their parameters.In order to ensure success in import substitution it is necessary to create a prospective system of technological machinery that corresponds to new technologies and materials. Experience in creation of separate fragments of the machinery system reveals machinery similarity irrespective of construction complex sector. Such approach permits to create multi-functional technical facilities having not only similar basic machines but key equipment as well that differs only in design of finite element of working tool. It has been established that multi-functionality favours a significant reduction in financial expenses for renovation of machinery parks and an increase of modular machine number. It has been shown that the machinery system prompts in due time what technical facilities are to be created in order to realize non-waste technologies in the construction complex which are completed by production of certain useful products.

  13. 舰船旋转机械基础冲击动力学理论与实验研究%Experimental verification for modeling of rotating machinery under base-transferred shock excitations

    Institute of Scientific and Technical Information of China (English)

    赵元松; 贺少华; 吴新跃

    2014-01-01

    针对舰载旋转机械的水下非接触爆炸冲击动力学问题,提出了一种基础冲击转子-轴承系统建模理论。结合牛顿运动定理、动量矩定理和Timoshenko梁理论推导出了系统动力学微分方程,方程综合考虑了转子的旋转惯性力、剪切力、陀螺效应、轴向力、轴向扭矩以及轴承的油膜力。通过在时间域和空间域分别采用直接积分法和Galerkin有限单元法求解方程得到系统冲击响应的时间历程。最后,建立了一基础冲击旋转机械系统(转子系统)实验装置,并实验验证了建模理论和计算方法的正确性。%Model of a rotor system under base shock excitations was established. Multi-factors, including rotating inertia, shear force, gyroscopic effect, axial force, axial torque and oil film force, etc, were includ-ed. Dynamic differential equations were derived. Equations were solved by finite difference methods in time domain and FEM in space domain. Time-varying responses were obtained successfully. Finally, an experi-mental verification was carried out and the proposed theory was proved to be correct.

  14. The plastid-dividing machinery: formation, constriction and fission.

    Science.gov (United States)

    Yoshida, Yamato; Miyagishima, Shin-ya; Kuroiwa, Haruko; Kuroiwa, Tsuneyoshi

    2012-12-01

    Plastids divide by constriction of the plastid-dividing (PD) machinery, which encircles the division site. The PD machinery consists of the stromal inner machinery which includes the inner PD and filamenting temperature-sensitive mutant Z (FtsZ) rings and the cytosolic outer machinery which includes the outer PD and dynamin rings. The major constituent of the PD machinery is the outer PD ring, which consists of a bundle of polyglucan filaments. In addition, recent proteomic studies suggest that the PD machinery contains additional proteins that have not been characterized. The PD machinery forms from the inside to the outside of the plastid. The constriction seems to occur by sliding of the polyglucan filaments of the outer PD ring, aided by dynamin. The final fission of the plastid is probably promoted by the 'pinchase' activity of dynamin.

  15. Functional development of the circadian clock in the zebrafish pineal gland.

    Science.gov (United States)

    Ben-Moshe, Zohar; Foulkes, Nicholas S; Gothilf, Yoav

    2014-01-01

    The zebrafish constitutes a powerful model organism with unique advantages for investigating the vertebrate circadian timing system and its regulation by light. In particular, the remarkably early and rapid development of the zebrafish circadian system has facilitated exploring the factors that control the onset of circadian clock function during embryogenesis. Here, we review our understanding of the molecular basis underlying functional development of the central clock in the zebrafish pineal gland. Furthermore, we examine how the directly light-entrainable clocks in zebrafish cell lines have facilitated unravelling the general mechanisms underlying light-induced clock gene expression. Finally, we summarize how analysis of the light-induced transcriptome and miRNome of the zebrafish pineal gland has provided insight into the regulation of the circadian system by light, including the involvement of microRNAs in shaping the kinetics of light- and clock-regulated mRNA expression. The relative contributions of the pineal gland central clock and the distributed peripheral oscillators to the synchronization of circadian rhythms at the whole animal level are a crucial question that still remains to be elucidated in the zebrafish model.

  16. Translation-independent circadian control of the cell cycle in a unicellular photosynthetic eukaryote.

    Science.gov (United States)

    Miyagishima, Shin-ya; Fujiwara, Takayuki; Sumiya, Nobuko; Hirooka, Shunsuke; Nakano, Akihiko; Kabeya, Yukihiro; Nakamura, Mami

    2014-05-08

    Circadian rhythms of cell division have been observed in several lineages of eukaryotes, especially photosynthetic unicellular eukaryotes. However, the mechanism underlying the circadian regulation of the cell cycle and the nature of the advantage conferred remain unknown. Here, using the unicellular red alga Cyanidioschyzon merolae, we show that the G1/S regulator RBR-E2F-DP complex links the G1/S transition to circadian rhythms. Time-dependent E2F phosphorylation promotes the G1/S transition during subjective night and this phosphorylation event occurs independently of cell cycle progression, even under continuous dark or when cytosolic translation is inhibited. Constitutive expression of a phospho-mimic of E2F or depletion of RBR unlinks cell cycle progression from circadian rhythms. These transgenic lines are exposed to higher oxidative stress than the wild type. Circadian inhibition of cell cycle progression during the daytime by RBR-E2F-DP pathway likely protects cells from photosynthetic oxidative stress by temporally compartmentalizing photosynthesis and cell cycle progression.

  17. Circadian clock genes period and cycle regulate photoperiodic diapause in the bean bug Riptortus pedestris males.

    Science.gov (United States)

    Ikeno, Tomoko; Numata, Hideharu; Goto, Shin G

    2011-07-01

    The photoperiodic response is crucial for many insects to adapt to seasonal changes in temperate regions. It was recently shown that the circadian clock genes period (per) and cycle (cyc) are involved in the photoperiodic regulation of reproductive diapause in the bean bug Riptortus pedestris females. Here, we investigated the involvement of per and cyc both in the circadian rhythm of cuticle deposition and in the photoperiodic diapause of R. pedestris males using RNA interference (RNAi). RNAi of per and cyc disrupted the cuticle deposition rhythm and resulted in distinct cuticle layers. RNAi of per induced development of the male reproductive organs even under diapause-inducing short-day conditions, whereas RNAi of cyc suppressed development of the reproductive organs even under diapause-averting long-day conditions. Thus, the present study suggests that the circadian clock operated by per and cyc governs photoperiodism of males as that of females.

  18. Modeling circadian clocks: From equations to oscillations

    National Research Council Canada - National Science Library

    Gonze, Didier

    2011-01-01

    ... (such as light and temperature) is greatly helped by mathematical modeling. In the present paper we review some mathematical models for circadian clocks, ranging from abstract, phenomenological models to the most detailed molecular models...

  19. A database of circadian and diel rhythmic gene expression in the yellow fever mosquito Aedes aegypti.

    Science.gov (United States)

    Leming, Matthew T; Rund, Samuel S C; Behura, Susanta K; Duffield, Giles E; O'Tousa, Joseph E

    2014-12-17

    The mosquito species Aedes aegypti is the primary vector of many arboviral diseases, including dengue and yellow fevers, that are responsible for a large worldwide health burden. The biological rhythms of mosquitoes regulate many of the physiological processes and behaviors that influence the transmission of these diseases. For insight into the molecular basis of biological rhythms, diel and circadian gene expression profiling has been carried out for many species. To bring these resources to Aedes aegypti researchers, we used microarray technology to carry out a genome wide assessment of gene expression during the 24 hour light/dark (LD) cycle and during constant darkness (DD). The purpose of this report is to describe the methods, the validation of the results, and the organization of this database resource. The Aedes aegypti Circadian Database is a publicly accessible database that can be searched via a text-based query to visualize 44 hour temporal expression patterns of a given gene in Ae. aegypti heads under diel (observed under a 12 hour/12 hour LD cycle) and circadian (observed under DD) conditions. Profiles of gene expression under these conditions were assayed by Nimblegen 12-plex microarrays and rhythmicity was objectively assessed by the JTK_CYCLE algorithm. The output of the search is a graphical representation of the expression data along with computed period length, the time-of-day of gene expression peaks, and statistical determination for rhythmicity. Our results show that at least 7.9% of the gene set present in the Aedes aegypti head are rhythmic under LD conditions and 6.7% can be considered circadian, oscillating under constant dark conditions. We present these results in the Aedes aegypti Circadian Database through Bioclock, a public website hosted by the University of Notre Dame at http://www.nd.edu/~bioclock/. This website allows searchable browsing of this quantitative gene expression information. The visualization allows for gene

  20. ADHD, circadian rhythms and seasonality.

    Science.gov (United States)

    Wynchank, Dora S; Bijlenga, Denise; Lamers, Femke; Bron, Tannetje I; Winthorst, Wim H; Vogel, Suzan W; Penninx, Brenda W; Beekman, Aartjan T; Kooij, J Sandra

    2016-10-01

    We evaluated whether the association between Adult Attention-Deficit/Hyperactivity Disorder (ADHD) and Seasonal Affective Disorder (SAD) was mediated by the circadian rhythm. Data of 2239 persons from the Netherlands Study of Depression and Anxiety (NESDA) were used. Two groups were compared: with clinically significant ADHD symptoms (N = 175) and with No ADHD symptoms (N = 2064). Sleep parameters were sleep-onset and offset times, mid sleep and sleep duration from the Munich Chronotype Questionnaire. We identified the prevalence of probable SAD and subsyndromal SAD using the Seasonal Pattern Assessment Questionnaire (SPAQ). Clinically significant ADHD symptoms were identified by using a T score>65 on the Conners Adult ADHD Rating Scale. The prevalence of probable SAD was estimated at 9.9% in the ADHD group (vs. 3.3% in the No ADHD group) and of probable s-SAD at 12.5% in the ADHD group (vs 4.6% in the No ADHD group). Regression analyses showed consistently significant associations between ADHD symptoms and probable SAD, even after adjustment for current depression and anxiety, age, sex, education, use of antidepressants and benzodiazepines (B = 1.81, p < 0.001). Late self-reported sleep onset was an important mediator in the significant relationship between ADHD symptoms and probable SAD, even after correction for confounders (total model effects: B = 0.14, p ≤ 0.001). Both seasonal and circadian rhythm disturbances are significantly associated with ADHD symptoms. Delayed sleep onset time in ADHD may explain the increase in SAD symptoms. Treating patients with SAD for possible ADHD and delayed sleep onset time may reduce symptom severity in these complex patients. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Circadian Rhythms and Obesity in Mammals

    OpenAIRE

    Oren Froy

    2012-01-01

    Obesity has become a serious public health problem and a major risk factor for the development of illnesses, such as insulin resistance and hypertension. Attempts to understand the causes of obesity and develop new therapeutic strategies have mostly focused on caloric intake and energy expenditure. Recent studies have shown that the circadian clock controls energy homeostasis by regulating the circadian expression and/or activity of enzymes, hormones, and transport systems involved in metabol...

  2. Circadian rhythms, sleep, and the menstrual cycle.

    Science.gov (United States)

    Baker, Fiona C; Driver, Helen S

    2007-09-01

    Women with ovulatory menstrual cycles have a circadian rhythm superimposed on the menstrual-associated rhythm; in turn, menstrual events affect the circadian rhythm. In this paper, we review circadian rhythms in temperature, selected hormone profiles, and sleep-wake behavior in healthy women at different phases of the menstrual cycle. The effects on menstrual cycle rhythmicity of disrupted circadian rhythms, for example, with shiftwork and altered circadian rhythms in women with menstrual-related mood disturbances, are discussed. Compared to the follicular phase, in the post-ovulation luteal phase, body temperature is elevated, but the amplitude of the temperature rhythm is reduced. Evidence indicates that the amplitude of other rhythms, such as melatonin and cortisol, may also be blunted in the luteal phase. Subjective sleep quality is lowest around menses, but the timing and composition of sleep remains relatively stable across the menstrual cycle in healthy women, apart from an increase in spindle frequency activity and a minor decrease in rapid eye movement (REM) sleep during the luteal phase. Disruption of circadian rhythms is associated with disturbances in menstrual function. Female shiftworkers compared to non-shiftworkers are more likely to report menstrual irregularity and longer menstrual cycles. There also is accumulating evidence that circadian disruption increases the risk of breast cancer in women, possibly due to altered light exposure and reduced melatonin secretion. Further investigations into the biological consequences of circadian disruption in women will offer insight into some menstrual-associated disorders, including mood changes, as well as reproductive function and possible links with breast cancer.

  3. Evolution of circadian organization in vertebrates

    Directory of Open Access Journals (Sweden)

    M. Menaker

    1997-03-01

    Full Text Available Circadian organization means the way in which the entire circadian system above the cellular level is put together physically and the principles and rules that determine the interactions among its component parts which produce overt rhythms of physiology and behavior. Understanding this organization and its evolution is of practical importance as well as of basic interest. The first major problem that we face is the difficulty of making sense of the apparently great diversity that we observe in circadian organization of diverse vertebrates. Some of this diversity falls neatly into place along phylogenetic lines leading to firm generalizations: i in all vertebrates there is a "circadian axis" consisting of the retinas, the pineal gland and the suprachiasmatic nucleus (SCN, ii in many non-mammalian vertebrates of all classes (but not in any mammals the pineal gland is both a photoreceptor and a circadian oscillator, and iii in all non-mammalian vertebrates (but not in any mammals there are extraretinal (and extrapineal circadian photoreceptors. An interesting explanation of some of these facts, especially the differences between mammals and other vertebrates, can be constructed on the assumption that early in their evolution mammals passed through a "nocturnal bottleneck". On the other hand, a good deal of the diversity among the circadian systems of vertebrates does not fall neatly into place along phylogenetic lines. In the present review we will consider how we might better understand such "phylogenetically incoherent" diversity and what sorts of new information may help to further our understanding of the evolution of circadian organization in vertebrates

  4. Rapid Adjustment of Circadian Clocks to Simulated Travel to Time Zones across the Globe.

    Science.gov (United States)

    Harrison, Elizabeth M; Gorman, Michael R

    2015-12-01

    Daily rhythms in mammalian physiology and behavior are generated by a central pacemaker located in the hypothalamic suprachiasmatic nuclei (SCN), the timing of which is set by light from the environment. When the ambient light-dark cycle is shifted, as occurs with travel across time zones, the SCN and its output rhythms must reset or re-entrain their phases to match the new schedule-a sluggish process requiring about 1 day per hour shift. Using a global assay of circadian resetting to 6 equidistant time-zone meridians, we document this characteristically slow and distance-dependent resetting of Syrian hamsters under typical laboratory lighting conditions, which mimic summer day lengths. The circadian pacemaker, however, is additionally entrainable with respect to its waveform (i.e., the shape of the 24-h oscillation) allowing for tracking of seasonally varying day lengths. We here demonstrate an unprecedented, light exposure-based acceleration in phase resetting following 2 manipulations of circadian waveform. Adaptation of circadian waveforms to long winter nights (8 h light, 16 h dark) doubled the shift response in the first 3 days after the shift. Moreover, a bifurcated waveform induced by exposure to a novel 24-h light-dark-light-dark cycle permitted nearly instant resetting to phase shifts from 4 to 12 h in magnitude, representing a 71% reduction in the mismatch between the activity rhythm and the new photocycle. Thus, a marked enhancement of phase shifting can be induced via nonpharmacological, noninvasive manipulation of the circadian pacemaker waveform in a model species for mammalian circadian rhythmicity. Given the evidence of conserved flexibility in the human pacemaker waveform, these findings raise the promise of flexible resetting applicable to circadian disruption in shift workers, frequent time-zone travelers, and any individual forced to adjust to challenging schedules. © 2015 The Author(s).

  5. Circadian and dark-pulse activation of orexin/hypocretin neurons

    Directory of Open Access Journals (Sweden)

    Marston Oliver J

    2008-12-01

    Full Text Available Temporal control of brain and behavioral states emerges as a consequence of the interaction between circadian and homeostatic neural circuits. This interaction permits the daily rhythm of sleep and wake, regulated in parallel by circadian cues originating from the suprachiasmatic nuclei (SCN and arousal-promoting signals arising from the orexin-containing neurons in the tuberal hypothalamus (TH. Intriguingly, the SCN circadian clock can be reset by arousal-promoting stimuli while activation of orexin/hypocretin neurons is believed to be under circadian control, suggesting the existence of a reciprocal relationship. Unfortunately, since orexin neurons are themselves activated by locomotor promoting cues, it is unclear how these two systems interact to regulate behavioral rhythms. Here mice were placed in conditions of constant light, which suppressed locomotor activity, but also revealed a highly pronounced circadian pattern in orexin neuronal activation. Significantly, activation of orexin neurons in the medial and lateral TH occurred prior to the onset of sustained wheel-running activity. Moreover, exposure to a 6 h dark pulse during the subjective day, a stimulus that promotes arousal and phase advances behavioral rhythms, activated neurons in the medial and lateral TH including those containing orexin. Concurrently, this stimulus suppressed SCN activity while activating cells in the median raphe. In contrast, dark pulse exposure during the subjective night did not reset SCN-controlled behavioral rhythms and caused a transient suppression of neuronal activation in the TH. Collectively these results demonstrate, for the first time, pronounced circadian control of orexin neuron activation and implicate recruitment of orexin cells in dark pulse resetting of the SCN circadian clock.

  6. Machinery fault diagnosis using joint global and local/nonlocal discriminant analysis with selective ensemble learning

    Science.gov (United States)

    Yu, Jianbo

    2016-11-01

    The vibration signals of faulty machine are generally non-stationary and nonlinear under those complicated working conditions. Thus, it is a big challenge to extract and select the effective features from vibration signals for machinery fault diagnosis. This paper proposes a new manifold learning algorithm, joint global and local/nonlocal discriminant analysis (GLNDA), which aims to extract effective intrinsic geometrical information from the given vibration data. Comparisons with other regular methods, principal component analysis (PCA), local preserving projection (LPP), linear discriminant analysis (LDA) and local LDA (LLDA), illustrate the superiority of GLNDA in machinery fault diagnosis. Based on the extracted information by GLNDA, a GLNDA-based Fisher discriminant rule (FDR) is put forward and applied to machinery fault diagnosis without additional recognizer construction procedure. By importing Bagging into GLNDA score-based feature selection and FDR, a novel manifold ensemble method (selective GLNDA ensemble, SE-GLNDA) is investigated for machinery fault diagnosis. The motivation for developing ensemble of manifold learning components is that it can achieve higher accuracy and applicability than single component in machinery fault diagnosis. The effectiveness of the SE-GLNDA-based fault diagnosis method has been verified by experimental results from bearing full life testers.

  7. Neuroimaging, cognition, light and circadian rhythms

    Directory of Open Access Journals (Sweden)

    Giulia eGaggioni

    2014-07-01

    Full Text Available In humans, sleep and wakefulness and the associated cognitive processes are regulated through interactions between sleep homeostasis and the circadian system. Chronic disruption of sleep and circadian rhythmicity is common in our society and there is a need for a better understanding of the brain mechanisms regulating sleep, wakefulness and associated cognitive processes. This review summarizes recent investigations which provide first neural correlates of the combined influence of sleep homeostasis and circadian rhythmicity on cognitive brain activity. Markers of interindividual variations in sleep-wake regulation, such as chronotype and polymorphisms in sleep and clock genes, are associated with changes in cognitive brain responses in subcortical and cortical areas in response to manipulations of the sleep-wake cycle. This review also includes recent data showing that cognitive brain activity is regulated by light, which is a powerful modulator of cognition and alertness and also directly impacts sleep and circadian rhythmicity. The effect of light varied with age, psychiatric status, PERIOD3 genotype and changes in sleep homeostasis and circadian phase. These data provide new insights into the contribution of demographic characteristics, the sleep-wake cycle, circadian rhythmicity and light to brain functioning.

  8. Circadian genes, the stress axis, and alcoholism.

    Science.gov (United States)

    Sarkar, Dipak K

    2012-01-01

    The body's internal system to control the daily rhythm of the body's functions (i.e., the circadian system), the body's stress response, and the body's neurobiology are highly interconnected. Thus, the rhythm of the circadian system impacts alcohol use patterns; at the same time, alcohol drinking also can alter circadian functions. The sensitivity of the circadian system to alcohol may result from alcohol's effects on the expression of several of the clock genes that regulate circadian function. The stress response system involves the hypothalamus and pituitary gland in the brain and the adrenal glands, as well as the hormones they secrete, including corticotrophin-releasing hormone, adrenocorticotrophic hormone, and glucocorticoids. It is controlled by brain-signaling molecules, including endogenous opioids such as β-endorphin. Alcohol consumption influences the activity of this system and vice versa. Finally, interactions exist between the circadian system, the hypothalamic-pituitary-adrenal axis, and alcohol consumption. Thus, it seems that certain clock genes may control functions of the stress response system and that these interactions are affected by alcohol.

  9. Personalized medicine for pathological circadian dysfunctions.

    Science.gov (United States)

    Skelton, Rachel L; Kornhauser, Jon M; Tate, Barbara A

    2015-01-01

    The recent approval of a therapeutic for a circadian disorder has increased interest in developing additional medicines for disorders characterized by circadian disruption. However, previous experience demonstrates that drug development for central nervous system (CNS) disorders has a high failure rate. Personalized medicine, or the approach to identifying the right treatment for the right patient, has recently become the standard for drug development in the oncology field. In addition to utilizing Companion Diagnostics (CDx) that identify specific genetic biomarkers to prescribe certain targeted therapies, patient profiling is regularly used to enrich for a responsive patient population during clinical trials, resulting in fewer patients required for statistical significance and a higher rate of success for demonstrating efficacy and hence receiving approval for the drug. This personalized medicine approach may be one mechanism that could reduce the high clinical trial failure rate in the development of CNS drugs. This review will discuss current circadian trials, the history of personalized medicine in oncology, lessons learned from a recently approved circadian therapeutic, and how personalized medicine can be tailored for use in future clinical trials for circadian disorders to ultimately lead to the approval of more therapeutics for patients suffering from circadian abnormalities.

  10. Circadian clock proteins in prokaryotes: hidden rhythms?

    Directory of Open Access Journals (Sweden)

    Maria eLoza-Correa

    2010-12-01

    Full Text Available Circadian clock genes are vital features of eukaryotes that have evolved such that organisms can adapt to our planet’s rotation in order to anticipate the coming day or night as well as unfavorable seasons. This circadian clock uses oscillation as a timekeeping element. However, circadian clock mechanisms exist also in prokaryotes. The circadian clock of Cyanobacteria is well studied. It is regulated by a cluster of three genes: kaiA, kaiB and kaiC. In this review, we will discuss the circadian system in cyanobacteria, and provide an overview and up-dated phylogenetic analysis of prokaryotic organisms that contain the main circadian genes. It is evident that the evolution of the kai genes has been influenced by lateral transfers but further and deeper studies are needed to get an in depth understanding of the exact evolutionary history of these genes. Interestingly, Legionella pneumophila an environmental bacterium and opportunistic human pathogen that parasitizes protozoa in fresh water environments also contains kaiB and kaiC, but their functions are not known. All of the residues described for the biochemical functions of the main pacemaker KaiC in Synechoccous elongates are also conserved in the L. pneumophila KaiC protein.

  11. Circadian clocks are resounding in peripheral tissues.

    Directory of Open Access Journals (Sweden)

    Andrey A Ptitsyn

    2006-03-01

    Full Text Available Circadian rhythms are prevalent in most organisms. Even the smallest disturbances in the orchestration of circadian gene expression patterns among different tissues can result in functional asynchrony, at the organism level, and may to contribute to a wide range of physiologic disorders. It has been reported that as many as 5%-10% of transcribed genes in peripheral tissues follow a circadian expression pattern. We have conducted a comprehensive study of circadian gene expression on a large dataset representing three different peripheral tissues. The data have been produced in a large-scale microarray experiment covering replicate daily cycles in murine white and brown adipose tissues as well as in liver. We have applied three alternative algorithmic approaches to identify circadian oscillation in time series expression profiles. Analyses of our own data indicate that the expression of at least 7% to 21% of active genes in mouse liver, and in white and brown adipose tissues follow a daily oscillatory pattern. Indeed, analysis of data from other laboratories suggests that the percentage of genes with an oscillatory pattern may approach 50% in the liver. For the rest of the genes, oscillation appears to be obscured by stochastic noise. Our phase classification and computer simulation studies based on multiple datasets indicate no detectable boundary between oscillating and non-oscillating fractions of genes. We conclude that greater attention should be given to the potential influence of circadian mechanisms on any biological pathway related to metabolism and obesity.

  12. 46 CFR 30.10-42 - Machinery space-TB/ALL.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Machinery space-TB/ALL. 30.10-42 Section 30.10-42...-42 Machinery space—TB/ALL. The term machinery space means any space that contains machinery and related equipment including Category A machinery spaces, propelling machinery, boilers, oil fuel...

  13. Differential expression of circadian clock genes in two strains of beetles reveals candidates related to photoperiodic induction of summer diapause.

    Science.gov (United States)

    Zhu, Li; Liu, Wen; Tan, Qian-Qian; Lei, Chao-Liang; Wang, Xiao-Ping

    2017-03-01

    Diapause (also known as dormancy) is a state of arrested development induced by photoperiod or temperature that allows insects to survive adverse environmental conditions. By regulating diapause induction, the circadian clock is involved in short-day-induced winter diapause but whether this is also the case in long-day (LD)-induced summer diapause remains unknown. The cabbage beetle Colaphellus bowringi could enter summer diapause under LD conditions. However, a non-photoperiodic-diapause (NPD) strain of this species, which was developed in our laboratory by artificial selection, could not enter diapause under LD photoperiod. Therefore, we identified circadian clock genes in this species and measured differences in their expression between a high diapause (HD) strain and the NPD strain to investigate the potential relationship between circadian clock genes and summer diapause induction in C. bowringi. We successfully cloned eight circadian clock genes and obtained intact ORFs of four; cryptochrome2, double-time, shaggy and vrille. Phylogenetic trees and sequence alignment analyses indicated that these circadian clock genes were conserved across insect taxa. The quantitative real-time PCR indicated that clock, cycle, period, timeless, cryptochrome2, and vrille were differentially expressed between HD and NPD strains reared under LD photoperiod during the diapause induction phase. These findings suggest the potential relationship between circadian clock genes and LD-regulated summer diapause induction in C. bowringi.

  14. Analysis of stationary displacement patterns in rotating machinery subject to local harmonic excitation

    Science.gov (United States)

    Österlind, Tomas; Kari, Leif; Nicolescu, Cornel Mihai

    2017-02-01

    Rotor vibration and stationary displacement patterns observed in rotating machineries subject to local harmonic excitation are analysed for improved understanding and dynamic characterization. The analysis stresses the importance of coordinate transformation between rotating and stationary frame of reference for accurate results and estimation of dynamic properties. A generic method which can be used for various rotor applications such as machine tool spindle and turbo machinery vibration is presented. The phenomenon shares similarities with stationary waves in rotating disks though focuses on vibration in shafts. The paper further proposes a graphical tool, the displacement map, which can be used for selection of stable rotational speed for rotating machinery. The results are validated through simulation of dynamic response of a milling cutter, which is a typical example of a variable speed rotor operating under different load conditions.

  15. The Autophagy Machinery Controls Cell Death Switching between Apoptosis and Necroptosis.

    Science.gov (United States)

    Goodall, Megan L; Fitzwalter, Brent E; Zahedi, Shadi; Wu, Min; Rodriguez, Diego; Mulcahy-Levy, Jean M; Green, Douglas R; Morgan, Michael; Cramer, Scott D; Thorburn, Andrew

    2016-05-23

    Although autophagy controls cell death and survival, underlying mechanisms are poorly understood, and it is unknown whether autophagy affects only whether or not cells die or also controls other aspects of programmed cell death. MAP3K7 is a tumor suppressor gene associated with poor disease-free survival in prostate cancer. Here, we report that Map3k7 deletion in mouse prostate cells sensitizes to cell death by TRAIL (TNF-related apoptosis-inducing ligand). Surprisingly, this death occurs primarily through necroptosis, not apoptosis, due to assembly of the necrosome in association with the autophagy machinery, mediated by p62/SQSTM1 recruitment of RIPK1. The mechanism of cell death switches to apoptosis if p62-dependent recruitment of the necrosome to the autophagy machinery is blocked. These data show that the autophagy machinery can control the mechanism of programmed cell death by serving as a scaffold rather than by degrading cargo.

  16. Assessment of the most significant causes of transportation and machinery accidents on collieries

    CSIR Research Space (South Africa)

    Oberholzer, JW

    1995-08-01

    Full Text Available The purpose of this study is to identify those areas, classified according to the SAMRASS data base system under the codes relating to underground transport and machinery type accidents that give cause to the greatest amount of accidents...

  17. Analysis of electric machinery and drive systems

    CERN Document Server

    Krause, Paul C; Sudhoff, Scott D; Pekarek, Steven

    2013-01-01

    Introducing a new edition of the popular reference on machine analysis Now in a fully revised and expanded edition, this widely used reference on machine analysis boasts many changes designed to address the varied needs of engineers in the electric machinery, electric drives, and electric power industries. The authors draw on their own extensive research efforts, bringing all topics up to date and outlining a variety of new approaches they have developed over the past decade. Focusing on reference frame theory that has been at the core of this work since the first edition, th

  18. Social memory in the rat: circadian variation and effect of circadian rhythm disruption

    NARCIS (Netherlands)

    Reijmers, L.G.J.E.; Leus, I.E.; Burbach, J.P.H.; Spruijt, B.M.; Ree, van J.M.

    2001-01-01

    Disruption of circadian rhythm can impair long-term passive avoidance memory of rats and mice. The present study investigated whether disruption of circadian rhythm can also impair social memory of male rats. Social memory was assessed using the social discrimination test, in which a short-term

  19. Social memory in the rat: circadian variation and effect of circadian rhythm disruption

    NARCIS (Netherlands)

    Reijmers, L.G.J.E.; Leus, I.E.; Burbach, J.P.H.; Spruijt, B.M.; Ree, van J.M.

    2001-01-01

    Disruption of circadian rhythm can impair long-term passive avoidance memory of rats and mice. The present study investigated whether disruption of circadian rhythm can also impair social memory of male rats. Social memory was assessed using the social discrimination test, in which a short-term olfa

  20. Disrupted light-dark cycle abolishes circadian expression of peripheral clock genes without inducing behavioral arrhythmicity in mice.

    Science.gov (United States)

    Oishi, Katsutaka; Higo-Yamamoto, Sayaka; Yamamoto, Saori; Yasumoto, Yuki

    2015-03-06

    The environmental light-dark (LD) cycle entrains the central circadian clock located in the suprachiasmatic nucleus (SCN) of mammals. The present study examined the effects of disrupted LD cycles on peripheral clocks in mice housed under a normal 12 h light-12 h dark cycle (LD 12:12) or an ultradian LD 3:3 cycle. Drinking behavior seemed to be free-running with a long period (26.03 h) under ultradian LD 3:3 cycles, in addition to light-induced direct suppression (masking effect). Core body temperature completely lost robust circadian rhythm and acquired a 6-h rhythm with a low amplitude under LD 3:3. Robust circadian expression of Per1, Per2, Clock and Bmal1 mRNAs was similarly flattened to intermediate levels in the liver, heart and white adipose tissue under LD 3:3. Robust circadian expression of Rev-erbα mRNA was completely damped in these tissues. Circadian expression of Dbp, a clock-controlled gene, was also disrupted in these tissues from mice housed under LD 3:3. The aberrant LD cycle seemed to induce the loss of circadian gene expression at the level of transcription, because rhythmic pre-mRNA expression of these genes was also abolished under LD 3:3. In addition to the direct effect of the aberrant LD cycle, abolished systemic time cues such as those of plasma corticosterone and body temperature might be involved in the disrupted expression of these circadian genes under LD 3:3. Our findings suggest that disrupted environmental LD cycles abolish the normal oscillation of peripheral clocks and induce internal desynchrony in mammals.

  1. Unraveling the complexities of circadian and sleep interactions with memory formation through invertebrate research

    Directory of Open Access Journals (Sweden)

    Maximilian eMichel

    2014-08-01

    Full Text Available Across phylogeny, the endogenous biological clock has been recognized as providing adaptive advantages to organisms through coordination of physiological and behavioral processes. Recent research has emphasized the role of circadian modulation of memory in generating peaks and troughs in cognitive performance. The circadian clock along with homeostatic processes also regulates sleep, which itself impacts the formation and consolidation of memory. Thus, the circadian clock, sleep and memory form a triad with ongoing dynamic interactions. With technological advances and the development of a global 24/7 society, understanding the mechanisms underlying these connections becomes pivotal for development of therapeutic treatments for memory disorders and to address issues in cognitive performance arising from non-traditional work schedules. Invertebrate models, such as Drosophila melanogaster and the mollusks Aplysia and Lymnaea, have proven invaluable tools for identification of highly conserved molecular processes in memory. Recent research from invertebrate systems has outlined the influence of sleep and the circadian clock upon synaptic plasticity. In this review, we discuss the effects of the circadian clock and sleep on memory formation in invertebrates drawing attention to the potential of in vivo and in vitro approaches that harness the power of simple invertebrate systems to correlate individual cellular processes with complex behaviors. In conclusion, this review highlights how studies in invertebrates with relatively simple nervous systems can provide mechanistic insights into corresponding behaviors in higher organisms and can be used to outline possible therapeutic options to guide further targeted inquiry.

  2. Unraveling the complexities of circadian and sleep interactions with memory formation through invertebrate research.

    Science.gov (United States)

    Michel, Maximilian; Lyons, Lisa C

    2014-01-01

    Across phylogeny, the endogenous biological clock has been recognized as providing adaptive advantages to organisms through coordination of physiological and behavioral processes. Recent research has emphasized the role of circadian modulation of memory in generating peaks and troughs in cognitive performance. The circadian clock along with homeostatic processes also regulates sleep, which itself impacts the formation and consolidation of memory. Thus, the circadian clock, sleep and memory form a triad with ongoing dynamic interactions. With technological advances and the development of a global 24/7 society, understanding the mechanisms underlying these connections becomes pivotal for development of therapeutic treatments for memory disorders and to address issues in cognitive performance arising from non-traditional work schedules. Invertebrate models, such as Drosophila melanogaster and the mollusks Aplysia and Lymnaea, have proven invaluable tools for identification of highly conserved molecular processes in memory. Recent research from invertebrate systems has outlined the influence of sleep and the circadian clock upon synaptic plasticity. In this review, we discuss the effects of the circadian clock and sleep on memory formation in invertebrates drawing attention to the potential of in vivo and in vitro approaches that harness the power of simple invertebrate systems to correlate individual cellular processes with complex behaviors. In conclusion, this review highlights how studies in invertebrates with relatively simple nervous systems can provide mechanistic insights into corresponding behaviors in higher organisms and can be used to outline possible therapeutic options to guide further targeted inquiry.

  3. Cross-talk between the cellular redox state and the circadian system in Neurospora.

    Science.gov (United States)

    Yoshida, Yusuke; Iigusa, Hideo; Wang, Niyan; Hasunuma, Kohji

    2011-01-01

    The circadian system is composed of a number of feedback loops, and multiple feedback loops in the form of oscillators help to maintain stable rhythms. The filamentous fungus Neurospora crassa exhibits a circadian rhythm during asexual spore formation (conidiation banding) and has a major feedback loop that includes the FREQUENCY (FRQ)/WHITE COLLAR (WC) -1 and -2 oscillator (FWO). A mutation in superoxide dismutase (sod)-1, an antioxidant gene, causes a robust and stable circadian rhythm compared with that of wild-type (Wt). However, the mechanisms underlying the functions of reactive oxygen species (ROS) remain unknown. Here, we show that cellular ROS concentrations change in a circadian manner (ROS oscillation), and the amplitudes of ROS oscillation increase with each cycle and then become steady (ROS homeostasis). The ROS oscillation and homeostasis are produced by the ROS-destroying catalases (CATs) and ROS-generating NADPH oxidase (NOX). cat-1 is also induced by illumination, and it reduces ROS levels. Although ROS oscillation persists in the absence of frq, wc-1 or wc-2, its homeostasis is altered. Furthermore, genetic and biochemical evidence reveals that ROS concentration regulates the transcriptional function of WCC and a higher ROS concentration enhances conidiation banding. These findings suggest that the circadian system engages in cross-talk with the cellular redox state via ROS-regulatory factors.

  4. A systematic survey in Arabidopsis thaliana of transcription factors that modulate circadian parameters

    Directory of Open Access Journals (Sweden)

    Merkle Thomas

    2008-04-01

    Full Text Available Abstract Background Plant circadian systems regulate various biological processes in harmony with daily environmental changes. In Arabidopsis thaliana, the underlying clock mechanism is comprised of multiple integrated transcriptional feedbacks, which collectively lead to global patterns of rhythmic gene expression. The transcriptional networks are essential within the clock itself and in its output pathway. Results Here, to expand understanding of transcriptional networks within and associated to the clock, we performed both an in silico analysis of transcript rhythmicity of transcription factor genes, and a pilot assessment of functional phenomics on the MYB, bHLH, and bZIP families. In our in silico analysis, we defined which members of these families express a circadian waveform of transcript abundance. Up to 20% of these families were over-represented as clock-controlled genes. To detect members that contribute to proper oscillator function, we systematically measured rhythmic growth via an imaging system in hundreds of misexpression lines targeting members of the transcription-factor families. Three transcription factors were found that conferred aberrant circadian rhythms when misexpressed: MYB3R2, bHLH69, and bHLH92. Conclusion Transcript abundance of many transcription factors in Arabidopsis oscillates in a circadian manner. Further, a developed pipeline assessed phenotypic contribution of a panel of transcriptional regulators in the circadian system.

  5. Systems-level characterization of the kernel mechanism of the cyanobacterial circadian oscillator.

    Science.gov (United States)

    Ma, Lan; Ranganathan, Rama

    2014-03-01

    Circadian clock is an essential molecular regulatory mechanism that coordinates daily biological processes. Toward understanding the design principles of the circadian mechanism in cyanobacteria, the only prokaryotes reported to possess circadian rhythmicity, mathematical models have been used as important tools to help elucidate the complicated biochemical processes. In this study, we focus on elucidating the underlying systems properties that drive the oscillation of the cyanobacterial clockwork. We apply combined methods of time scale separation, phase space analysis, bifurcation analysis and sensitivity analysis to a model of the in vitro cyanobacterial circadian clock proposed by us recently. The original model is reduced to a three-dimensional slow subsystem by time scale separation. Phase space analysis of the reduced subsystem shows that the null-surface of the Serine-phosphorylated state (S-state) of KaiC is a bistable surface, and that the characteristic of the phase portrait indicates that the kernel mechanism of the clockwork behaves as a relaxation oscillator induced by interlinked positive and negative feedback loops. Phase space analysis together with perturbation analysis supports our previous viewpoint that the S-state of KaiC is plausibly a key component for the protein regulatory network of the cyanobacterial circadian clock.

  6. Circadian clock regulation of the cell cycle in the zebrafish intestine.

    Directory of Open Access Journals (Sweden)

    Elodie Peyric

    Full Text Available The circadian clock controls cell proliferation in a number of healthy tissues where cell renewal and regeneration are critical for normal physiological function. The intestine is an organ that typically undergoes regular cycles of cell division, differentiation and apoptosis as part of its role in digestion and nutrient absorption. The aim of this study was to explore circadian clock regulation of cell proliferation and cell cycle gene expression in the zebrafish intestine. Here we show that the zebrafish gut contains a directly light-entrainable circadian pacemaker, which regulates the daily timing of mitosis. Furthermore, this intestinal clock controls the expression of key cell cycle regulators, such as cdc2, wee1, p21, PCNA and cdk2, but only weakly influences cyclin B1, cyclin B2 and cyclin E1 expression. Interestingly, food deprivation has little impact on circadian clock function in the gut, but dramatically reduces cell proliferation, as well as cell cycle gene expression in this tissue. Timed feeding under constant dark conditions is able to drive rhythmic expression not only of circadian clock genes, but also of several cell cycle genes, suggesting that food can entrain the clock, as well as the cell cycle in the intestine. Rather surprisingly, we found that timed feeding is critical for high amplitude rhythms in cell cycle gene expression, even when zebrafish are maintained on a light-dark cycle. Together these results suggest that the intestinal clock integrates multiple rhythmic cues, including light and food, to function optimally.

  7. KAYAK-α modulates circadian transcriptional feedback loops in Drosophila pacemaker neurons.

    Science.gov (United States)

    Ling, Jinli; Dubruille, Raphaëlle; Emery, Patrick

    2012-11-21

    Circadian rhythms are generated by well-conserved interlocked transcriptional feedback loops in animals. In Drosophila, the dimeric transcription factor CLOCK/CYCLE (CLK/CYC) promotes period (per), timeless (tim), vrille (vri), and PAR-domain protein 1 (Pdp1) transcription. PER and TIM negatively feed back on CLK/CYC transcriptional activity, whereas VRI and PDP1 negatively and positively regulate Clk transcription, respectively. Here, we show that the α isoform of the Drosophila FOS homolog KAYAK (KAY) is required for normal circadian behavior. KAY-α downregulation in circadian pacemaker neurons increases period length by 1.5 h. This behavioral phenotype is correlated with decreased expression of several circadian proteins. The strongest effects are on CLK and the neuropeptide PIGMENT DISPERSING FACTOR, which are both under VRI and PDP1 control. Consistently, KAY-α can bind to VRI and inhibit its interaction with the Clk promoter. Interestingly, KAY-α can also repress CLK activity. Hence, in flies with low KAY-α levels, CLK derepression would partially compensate for increased VRI repression, thus attenuating the consequences of KAY-α downregulation on CLK targets. We propose that the double role of KAY-α in the two transcriptional loops controlling Drosophila circadian behavior brings precision and stability to their oscillations.

  8. CIRCADIAN CLOCK-ASSOCIATED 1 regulates ROS homeostasis and oxidative stress responses.

    Science.gov (United States)

    Lai, Alvina Grace; Doherty, Colleen J; Mueller-Roeber, Bernd; Kay, Steve A; Schippers, Jos H M; Dijkwel, Paul P

    2012-10-16

    Organisms have evolved endogenous biological clocks as internal timekeepers to coordinate metabolic processes with the external environment. Here, we seek to understand the mechanism of synchrony between the oscillator and products of metabolism known as Reactive Oxygen Species (ROS) in Arabidopsis thaliana. ROS-responsive genes exhibit a time-of-day-specific phase of expression under diurnal and circadian conditions, implying a role of the circadian clock in transcriptional regulation of these genes. Hydrogen peroxide production and scavenging also display time-of-day phases. Mutations in the core-clock regulator, CIRCADIAN CLOCK ASSOCIATED 1 (CCA1), affect the transcriptional regulation of ROS-responsive genes, ROS homeostasis, and tolerance to oxidative stress. Mis-expression of EARLY FLOWERING 3, LUX ARRHYTHMO, and TIMING OF CAB EXPRESSION 1 affect ROS production and transcription, indicating a global effect of the clock on the ROS network. We propose CCA1 as a master regulator of ROS homeostasis through association with the Evening Element in promoters of ROS genes in vivo to coordinate time-dependent responses to oxidative stress. We also find that ROS functions as an input signal that affects the transcriptional output of the clock, revealing an important link between ROS signaling and circadian output. Temporal coordination of ROS signaling by CCA1 and the reciprocal control of circadian output by ROS reveal a mechanistic link that allows plants to master oxidative stress responses.

  9. Integration of microRNA miR-122 in hepatic circadian gene expression.

    Science.gov (United States)

    Gatfield, David; Le Martelot, Gwendal; Vejnar, Charles E; Gerlach, Daniel; Schaad, Olivier; Fleury-Olela, Fabienne; Ruskeepää, Anna-Liisa; Oresic, Matej; Esau, Christine C; Zdobnov, Evgeny M; Schibler, Ueli

    2009-06-01

    In liver, most metabolic pathways are under circadian control, and hundreds of protein-encoding genes are thus transcribed in a cyclic fashion. Here we show that rhythmic transcription extends to the locus specifying miR-122, a highly abundant, hepatocyte-specific microRNA. Genetic loss-of-function and gain-of-function experiments have identified the orphan nuclear receptor REV-ERBalpha as the major circadian regulator of mir-122 transcription. Although due to its long half-life mature miR-122 accumulates at nearly constant rates throughout the day, this miRNA is tightly associated with control mechanisms governing circadian gene expression. Thus, the knockdown of miR-122 expression via an antisense oligonucleotide (ASO) strategy resulted in the up- and down-regulation of hundreds of mRNAs, of which a disproportionately high fraction accumulates in a circadian fashion. miR-122 has previously been linked to the regulation of cholesterol and lipid metabolism. The transcripts associated with these pathways indeed show the strongest time point-specific changes upon miR-122 depletion. The identification of Pparbeta/delta and the peroxisome proliferator-activated receptor alpha (PPARalpha) coactivator Smarcd1/Baf60a as novel miR-122 targets suggests an involvement of the circadian metabolic regulators of the PPAR family in miR-122-mediated metabolic control.

  10. Circadian clock regulation of the cell cycle in the zebrafish intestine.

    Science.gov (United States)

    Peyric, Elodie; Moore, Helen A; Whitmore, David

    2013-01-01

    The circadian clock controls cell proliferation in a number of healthy tissues where cell renewal and regeneration are critical for normal physiological function. The intestine is an organ that typically undergoes regular cycles of cell division, differentiation and apoptosis as part of its role in digestion and nutrient absorption. The aim of this study was to explore circadian clock regulation of cell proliferation and cell cycle gene expression in the zebrafish intestine. Here we show that the zebrafish gut contains a directly light-entrainable circadian pacemaker, which regulates the daily timing of mitosis. Furthermore, this intestinal clock controls the expression of key cell cycle regulators, such as cdc2, wee1, p21, PCNA and cdk2, but only weakly influences cyclin B1, cyclin B2 and cyclin E1 expression. Interestingly, food deprivation has little impact on circadian clock function in the gut, but dramatically reduces cell proliferation, as well as cell cycle gene expression in this tissue. Timed feeding under constant dark conditions is able to drive rhythmic expression not only of circadian clock genes, but also of several cell cycle genes, suggesting that food can entrain the clock, as well as the cell cycle in the intestine. Rather surprisingly, we found that timed feeding is critical for high amplitude rhythms in cell cycle gene expression, even when zebrafish are maintained on a light-dark cycle. Together these results suggest that the intestinal clock integrates multiple rhythmic cues, including light and food, to function optimally.

  11. Tasimelteon, a melatonin agonist for the treatment of insomnia and circadian rhythm sleep disorders.

    Science.gov (United States)

    Hardeland, Rüdiger

    2009-07-01

    Tasimelteon, developed by Vanda Pharmaceuticals Inc under license from Bristol-Myers Squibb Co, is a melatonin receptor agonist. Because of the high density of melatonin receptors in the circadian pacemaker, the suprachiasmatic nucleus, melatonergic actions can phase-shift circadian rhythms and promote sleep. Tasimelteon was effective in reducing sleep onset latency (in phase II and III clinical trials) and in resetting the circadian melatonin rhythm (in phase II trials), which indicated its potential suitability as treatment for jet lag, shift work and circadian rhythm sleep disorders. Statistically significant improvements in sleep maintenance have also been observed with the drug. Tasimelteon has been claimed to be useful in the treatment of depression, and preclinical evidence in this respect is to be confirmed in a phase II clinical trial, which was ready to be initiated at the time of publication. It is plausible that the drug may be effective in the treatment of depressive disorders, at least those that are related to circadian dysfunction, and that it may attenuate sleep problems in depressed patients of different subtypes. A general suitability in mitigating other symptoms of major depressive disorder cannot be deduced from the actions of tasimelteon via the melatonin receptors MT1 and MT2. The drug is well tolerated, does not induce impairment of next-day functioning or dependence, and seems to be safe in short-term treatment; however, toxicological data would be required for assessing its long-term safety.

  12. Lithium impacts on the amplitude and period of the molecular circadian clockwork.

    Directory of Open Access Journals (Sweden)

    Jian Li

    Full Text Available Lithium salt has been widely used in treatment of Bipolar Disorder, a mental disturbance associated with circadian rhythm disruptions. Lithium mildly but consistently lengthens circadian period of behavioural rhythms in multiple organisms. To systematically address the impacts of lithium on circadian pacemaking and the underlying mechanisms, we measured locomotor activity in mice in vivo following chronic lithium treatment, and also tracked clock protein dynamics (PER2::Luciferase in vitro in lithium-treated tissue slices/cells. Lithium lengthens period of both the locomotor activity rhythms, as well as the molecular oscillations in the suprachiasmatic nucleus, lung tissues and fibroblast cells. In addition, we also identified significantly elevated PER2::LUC expression and oscillation amplitude in both central and peripheral pacemakers. Elevation of PER2::LUC by lithium was not associated with changes in protein stabilities of PER2, but instead with increased transcription of Per2 gene. Although lithium and GSK3 inhibition showed opposing effects on clock period, they acted in a similar fashion to up-regulate PER2 expression and oscillation amplitude. Collectively, our data have identified a novel amplitude-enhancing effect of lithium on the PER2 protein rhythms in the central and peripheral circadian clockwork, which may involve a GSK3-mediated signalling pathway. These findings may advance our understanding of the therapeutic actions of lithium in Bipolar Disorder or other psychiatric diseases that involve circadian rhythm disruptions.

  13. Application of multiparametric procedures for assessing the heritability of circadian health.

    Science.gov (United States)

    Lopez-Minguez, J; Colodro-Conde, L; Bandín, C; Ordoñana, J R; Garaulet, M; Madrid, J A

    2016-01-01

    At present, the measurement of circadian system status under free-living conditions by the use of sensors is a relatively new technique. The data obtained using these methods are influenced by strong environmental masking factors and artifacts that can affect its recording. Therefore, the use of integrative variables such as TAP, a measure that includes temperature, activity and position that reduces these drawbacks and the number of parameters obtained is necessary. However, the relative genetic contribution to this circadian marker is unknown. The aim of our study was to ascertain the relative importance of genetic influences in TAP, and for each of its components using classical twin models. The study was performed in 53 pairs of female twins [28 monozygotic (MZ) and 25 dizygotic (DZ)] with mean age 52 ± 6 years. Circadian patterns were studied by analyzing temperature, body position and activity for 1 week every 1 min with "Circadianware®.". Genetic influences affecting the variability of each of the measurements were estimated by comparing the observed data in twin pairs. MZ twins showed higher intrapair correlations than DZ twins for most of the parameters. Genetic factors (broad sense heritability) were responsible for about 40-72% of TAP variance in parameters such as mesor, acrophase, amplitude, Rayleigh test, percentage of rhythmicity and circadian function index. We found more homogeneous heritability estimates of the circadian system when using an integrative technique such as TAP than with individual variables alone, suggesting that this measurement can be more reliable and less subject to environmental artifacts.

  14. Rotating Machinery Predictive Maintenance Through Expert System

    Directory of Open Access Journals (Sweden)

    M. Sarath Kumar

    2000-01-01

    Full Text Available Modern rotating machines such as turbomachines, either produce or absorb huge amount of power. Some of the common applications are: steam turbine-generator and gas turbine-compressor-generator trains produce power and machines, such as pumps, centrifugal compressors, motors, generators, machine tool spindles, etc., are being used in industrial applications. Condition-based maintenance of rotating machinery is a common practice where the machine's condition is monitored constantly, so that timely maintenance can be done. Since modern machines are complex and the amount of data to be interpreted is huge, we need precise and fast methods in order to arrive at the best recommendations to prevent catastrophic failure and to prolong the life of the equipment. In the present work using vibration characteristics of a rotor-bearing system, the condition of a rotating machinery (electrical rotor is predicted using an off-line expert system. The analysis of the problem is carried out in an Object Oriented Programming (OOP framework using the finite element method. The expert system which is also developed in an OOP paradigm gives the type of the malfunctions, suggestions and recommendations. The system is implemented in C++.

  15. Evolution of the chloroplast division machinery

    Institute of Scientific and Technical Information of China (English)

    Hongbo GAO; Fuli GAO

    2011-01-01

    Chloroplasts are photosynthetic organelles derived from endosymbiotic cyanobacteria during evolution.Dramatic changes occurred during the process of the formation and evolution of chloroplasts,including the large-scale gene transfer from chloroplast to nucleus.However,there are still many essential characters remaining.For the chloroplast division machinery,FtsZ proteins,Ftn2,SulA and part of the division site positioning system- MinD and MinE are still conserved.New or at least partially new proteins,such as FtsZ family proteins FtsZl and ARC3,ARC6H,ARC5,PDV1,PDV2 and MCD1,were introduced for the division of chloroplasts during evolution.Some bacterial cell division proteins,such as FtsA,MreB,Ftn6,FtsW and Ftsl,probably lost their function or were gradually lost.Thus,the chloroplast division machinery is a dynamically evolving structure with both conservation and innovation.

  16. 肠道菌群失调与生物钟紊乱的相关性%Relationship between intestinal dysbacteriosis and circadian clock disturbance

    Institute of Scientific and Technical Information of China (English)

    黄文雅; 陆付耳; 董慧

    2015-01-01

    The human gut harbours a certain quantity and variety of microbes called intestinal flora, which is in a state of balance under normal circumstances, and dysbacteriosis occurs when the balance of the intestinal flora is dis-turbed by the host and the changes of the external environment.Circadian clock is the biological regulation system to adapt to natural circadian rhythm, including central clock and peripheral clock.Circadian clock disturbance, particularly rotating shift-workers with irregular light-night schedules, is associated with an increased risk of immune-related diseases.The de-velopment of these diseases is closely related to intestinal dysbacteriosis.Therefore, the correlation between intestinal dys-bacteriosis and circadian clock disturbance has attracted much attention.This review aims to explore the pathophysiological basis of the development in some immune-related diseases based on the latest scientific findings about the relationship be-tween intestinal microbial flora and circadian clock.

  17. A conserved DNA damage response pathway responsible for coupling the cell division cycle to the circadian and metabolic cycles.

    Science.gov (United States)

    Chen, Zheng; McKnight, Steven L

    2007-12-01

    The circadian clock drives endogenous oscillations of cellular and physiological processes with a periodicity of approximately 24 h. Progression of the cell division cycle (CDC) has been found to be coupled to the circadian clock, and it has been postulated that gating of the CDC by the circadian cycle may have evolved to protect DNA from the mutagenic effects of ultraviolet light. When grown under nutrient-limiting conditions in a chemostat, prototrophic strains of budding yeast, Saccharomyces cerevisiae, adopt a robust metabolic cycle of ultradian dimensions that temporally compartmentalizes essential cellular events. The CDC is gated by this yeast metabolic cycle (YMC), with DNA replication strictly segregated away from the oxidative phase when cells are actively respiring. Mutants impaired in such gating allow DNA replication to take place during the respiratory phase of the YMC and have been found to suffer significantly elevated rates of spontaneous mutation. Analogous to the circadian cycle, the YMC also employs the conserved DNA checkpoint kinase Rad53/Chk2 to facilitate coupling with the CDC. These studies highlight an evolutionarily conserved mechanism that seems to confine cell division to particular temporal windows to prevent DNA damage. We hypothesize that DNA damage itself might constitute a "zeitgeber", or time giver, for both the circadian cycle and the metabolic cycle. We discuss these findings in the context of a unifying theme underlying the circadian and metabolic cycles, and explore the relevance of cell cycle gating to human diseases including cancer.

  18. Cellular circadian clocks in mood disorders.

    Science.gov (United States)

    McCarthy, Michael J; Welsh, David K

    2012-10-01

    Bipolar disorder (BD) and major depressive disorder (MDD) are heritable neuropsychiatric disorders associated with disrupted circadian rhythms. The hypothesis that circadian clock dysfunction plays a causal role in these disorders has endured for decades but has been difficult to test and remains controversial. In the meantime, the discovery of clock genes and cellular clocks has revolutionized our understanding of circadian timing. Cellular circadian clocks are located in the suprachiasmatic nucleus (SCN), the brain's primary circadian pacemaker, but also throughout the brain and peripheral tissues. In BD and MDD patients, defects have been found in SCN-dependent rhythms of body temperature and melatonin release. However, these are imperfect and indirect indicators of SCN function. Moreover, the SCN may not be particularly relevant to mood regulation, whereas the lateral habenula, ventral tegmentum, and hippocampus, which also contain cellular clocks, have established roles in this regard. Dysfunction in these non-SCN clocks could contribute directly to the pathophysiology of BD/MDD. We hypothesize that circadian clock dysfunction in non-SCN clocks is a trait marker of mood disorders, encoded by pathological genetic variants. Because network features of the SCN render it uniquely resistant to perturbation, previous studies of SCN outputs in mood disorders patients may have failed to detect genetic defects affecting non-SCN clocks, which include not only mood-regulating neurons in the brain but also peripheral cells accessible in human subjects. Therefore, reporters of rhythmic clock gene expression in cells from patients or mouse models could provide a direct assay of the molecular gears of the clock, in cellular clocks that are likely to be more representative than the SCN of mood-regulating neurons in patients. This approach, informed by the new insights and tools of modern chronobiology, will allow a more definitive test of the role of cellular circadian clocks

  19. Circadian rhythms and food anticipatory behavior in Wfs1-deficient mice

    DEFF Research Database (Denmark)

    Luuk, Hendrik; Fahrenkrug, Jan; Hannibal, Jens

    2012-01-01

    in rodents with suprachiasmatic nucleus lesions. In the present study, we have characterized the circadian rhythmicity of behavior in Wfs1-deficient mice during ad libitum and restricted feeding. Based on the expression of Wfs1 protein in the DMH it was hypothesized that Wfs1-deficient mice will display...... in significantly lower body weight and reduced wheel-running activity. Circadian rhythmicity of behavior was normal in Wfs1-deficient mice under ad libitum feeding apart from elongated free-running period in constant light. The amount of food anticipatory activity induced by restricted feeding...

  20. Ontogeny of circadian clock gene expression in the pineal and the suprachiasmatic nucleus of chick embryo.

    Science.gov (United States)

    Okabayashi, Naritoshi; Yasuo, Shinobu; Watanabe, Miwa; Namikawa, Takao; Ebihara, Shizufumi; Yoshimura, Takashi

    2003-11-14

    Avian circadian rhythms are regulated by a multiple oscillatory system consisting of the pineal, the suprachiasmatic nucleus (SCN) and the eye. In the present study, ontogeny of circadian clock in the pineal and the SCN of chick embryo was examined using Per2 expression as a marker. A daily rhythmicity of Per2 expression was first detectable at embryonic day (ED) 18 in the pineal and at ED 16 in the SCN under light-dark (LD) cycles. The amplitude of the rhythmicity increased during the development. In contrast, little expression was observed during the development in constant darkness. These results suggest that although circadian clock matures by the end of the embryonic life in chicken, LD cycles are required for the expression of the Per2.

  1. On Development of Agricultural Machinery Operating Service in Chongqing

    Institute of Scientific and Technical Information of China (English)

    Chongjing; TAN; Shi; YANG

    2015-01-01

    Development of agricultural machinery operating service in Chongqing takes on rapid increase in number of service organizations,diversified service methods,improvement in service level,and constant service income. However,there are some problems,including unreasonable composition and small scale of service organization,imbalanced development of four service methods,low service level,and low operating income of agricultural machinery households. To accelerate development of agricultural machinery operating service in Chongqing,it is recommended to take following measures: adjusting subsidy for purchase and operation of agricultural machinery; improving fiscal and taxation and financial system; speeding up infrastructure construction,establishing agricultural machinery information network,and improving organizational form and methods of agricultural machinery operating service.

  2. The emerging roles of lipids in circadian control.

    Science.gov (United States)

    Adamovich, Yaarit; Aviram, Rona; Asher, Gad

    2015-08-01

    Lipids play vital roles in a wide variety of cellular functions. They act as structural components in cell membranes, serve as a major form of energy storage, and function as key signaling molecules. Mounting evidence points towards a tight interplay between lipids and circadian clocks. In mammals, circadian clocks regulate the daily physiology and metabolism, and disruption of circadian rhythmicity is associated with altered lipid homeostasis and pathologies such as fatty liver and obesity. Concomitantly, emerging evidence suggest that lipids are embedded within the core clock circuitry and participate in circadian control. Recent advances in lipidomics methodologies and their application in chronobiology studies have shed new light on the cross talk between circadian clocks and lipid homeostasis. We review herein the latest literature related to the involvement of lipids in circadian clock's function and highlight the contribution of circadian lipidomics studies to our understanding of circadian rhythmicity and lipid homeostasis. This article is part of a Special Issue entitled Brain Lipids.

  3. C4 photosynthetic machinery: insights from maize chloroplast proteomics

    Directory of Open Access Journals (Sweden)

    Qi eZhao

    2013-04-01

    Full Text Available C4 plants exhibit much higher CO2 assimilation rates than C3 plants. The specialized differentiation of mesophyll cell (M and bundle sheath cell (BS type chloroplasts is unique to C4 plants and improves photosynthesis efficiency. Maize (Zea mays is an important crop and model with C4 photosynthetic machinery. Current high-throughput quantitative proteomics approaches (e.g., 2DE, iTRAQ, and shotgun proteomics have been employed to investigate maize chloroplast structure and function. These proteomic studies have provided valuable information on C4 chloroplast protein components, photosynthesis, and other metabolic mechanisms underlying chloroplast biogenesis, stromal and membrane differentiation, as well as response to salinity, high/low temperature, and light stress. This review presents an overview of proteomics advances in maize chloroplast biology.

  4. MULTIFUNCTIONAL NANO-BIO MATERIALS WITHIN CELLULAR MACHINERY.

    Science.gov (United States)

    Rozhkova, E A; Ulasov, I V; Kim, D-H; Dimitrijevic, N M; Novosad, V; Bader, S D; Lesniak, M S; Rajh, T

    2011-08-01

    Functional nanoscale materials that possess specific physical or chemical properties can leverage energy transduction in vivo. Once these materials integrate with biomolecules they combine physical properties of inorganic material and the biorecognition capabilities of bio-organic moieties. Such nano-bio hybrids can be interfaced with living cells, the elementary functional units of life. These nano-bio systems are capable of bio-manipulation or actuation via altering intracellular biochemical pathways. Thus, nano-bio conjugates are appealing for a wide range of applications from the life sciences and nanomedicine to catalysis and clean energy production. Here we highlight recent progress in our efforts to develop smart nano-bio hybrid materials, and to study their performance within cellular machinery under application of external stimuli, such as light or magnetic fields.

  5. ABOUT ETHICS IN PLANT, MACHINERY AND EQUIPMENT VALUATION DOMAIN

    Directory of Open Access Journals (Sweden)

    Sorin Adrian Achim

    2015-09-01

    Full Text Available In this paper we put in discussion some ethical aspects of plant, machinery and equipment valuation. After a presentation of the general issues of ethics in valuation domain, we analyze the application of the fundamental ethical principles in plant, machinery and equipment valuation domain. To support our conclusions we use some findings of a study that we conducted to identify the particularities of the plant, machinery and equipment valuation activity in Romania.

  6. Melanopsin resets circadian rhythms in cells by inducing clock gene Period1

    Science.gov (United States)

    Yamashita, Shuhei; Uehara, Tomoe; Matsuo, Minako; Kikuchi, Yo; Numano, Rika

    2014-02-01

    The biochemical, physiological and behavioral processes are under the control of internal clocks with the period of approximately 24 hr, circadian rhythms. The expression of clock gene Period1 (Per1) oscillates autonomously in cells and is induced immediately after a light pulse. Per1 is an indispensable member of the central clock system to maintain the autonomous oscillator and synchronize environmental light cycle. Per1 expression could be detected by Per1∷luc and Per1∷GFP plasmid DNA in which firefly luciferase and Green Fluorescence Protein were rhythmically expressed under the control of the mouse Per1 promoter in order to monitor mammalian circadian rhythms. Membrane protein, MELANOPSIN is activated by blue light in the morning on the retina and lead to signals transduction to induce Per1 expression and to reset the phase of circadian rhythms. In this report Per1 induction was measured by reporter signal assay in Per1∷luc and Per1∷GFP fibroblast cell at the input process of circadian rhythms. To the result all process to reset the rhythms by Melanopsin is completed in single cell like in the retina projected to the central clock in the brain. Moreover, the phase of circadian rhythm in Per1∷luc cells is synchronized by photo-activated Melanopsin, because the definite peak of luciferase activity in one dish was found one day after light illumination. That is an available means that physiological circadian rhythms could be real-time monitor as calculable reporter (bioluminescent and fluorescent) chronological signal in both single and groups of cells.

  7. Relationships between circadian rhythms and ethanol intake in mice

    OpenAIRE

    Trujillo, Jennifer L.

    2009-01-01

    This dissertation integrates methods from alcohol and circadian rhythms research to explore relationships between ethanol and circadian rhythms in mice. Ingesting alcohol at certain times of day differentially affects the body; circadian rhythms also impact preference for drinking alcohol at different times of day. The influence of circadian timing on development and maintenance of ethanol drinking patterns was studied in Chapter 2. This showed how establishing a history of ethanol exposure a...

  8. Circadian Regulation of Cortisol Release in Behaviorally Split Golden Hamsters

    OpenAIRE

    2011-01-01

    The master circadian clock located within the hypothalamic suprachiasmatic nucleus (SCN) is necessary for the circadian rhythm of glucocorticoid (GC) release. The pathways by which the SCN sustains rhythmic GC release remain unclear. We studied the circadian regulation of cortisol release in the behaviorally split golden hamster, in which the single bout of circadian locomotor activity splits into two bouts approximately12 h apart after exposing the animals to constant light conditions. We sh...

  9. Isochron-Based Phase Response Analysis of Circadian Rhythms

    OpenAIRE

    Gunawan, Rudiyanto; Doyle, Francis J.

    2006-01-01

    Circadian rhythms possess the ability to robustly entrain to the environmental cycles. This ability relies on the phase synchronization of circadian rhythm gene regulation to different environmental cues, of which light is the most obvious and important. The elucidation of the mechanism of circadian entrainment requires an understanding of circadian phase behavior. This article presents two phase analyses of oscillatory systems for infinitesimal and finite perturbations based on isochrons as ...

  10. Circadian clocks and cell division: What's the pacemaker?

    OpenAIRE

    Johnson, Carl Hirschie

    2010-01-01

    Evolution has selected a system of two intertwined cell cycles: the cell division cycle (CDC) and the daily (circadian) biological clock. The circadian clock keeps track of solar time and programs biological processes to occur at environmentally appropriate times. One of these processes is the CDC, which is often gated by the circadian clock. The intermeshing of these two cell cycles is probably responsible for the observation that disruption of the circadian system enhances susceptibility to...

  11. Acute and phase-shifting effects of ocular and extraocular light in human circadian physiology

    NARCIS (Netherlands)

    Ruger, M; Gordijn, MCM; Beersma, DGM; de Vries, B; Daan, S

    2003-01-01

    Light can influence physiology and performance of humans in two distinct ways. It can acutely change the level of physiological and behavioral parameters, and it can induce a phase shift in the circadian oscillators underlying variations in these levels. Until recently, both effects were thought to

  12. Synchrony and Desynchrony in Circadian Clocks: Impacts on Learning and Memory

    Science.gov (United States)

    Krishnan, Harini C.; Lyons, Lisa C.

    2015-01-01

    Circadian clocks evolved under conditions of environmental variation, primarily alternating light dark cycles, to enable organisms to anticipate daily environmental events and coordinate metabolic, physiological, and behavioral activities. However, modern lifestyle and advances in technology have increased the percentage of individuals working in…

  13. General Course of Failure Distributions at Complex Machineries

    Directory of Open Access Journals (Sweden)

    Naqib Daneshjo

    2017-02-01

    Full Text Available In the process of maintenance management of machinery and devices there is necessity to keep in the mind "construction technologicity” (ability of construction technology. This term is used in evaluating of machinery construction, their groups and components in terms of production. The aim of management and planning maintenance of machinery is the failure-free operation in the application process. The range of machinery maintenance machines from routine one and inspection to general repairs is important to organize in a way to prevent unplanned idle time and failures or very likely to accidents.

  14. Circadian and Wakefulness-Sleep Modulation of Cognition in Humans

    Directory of Open Access Journals (Sweden)

    Kenneth P Wright

    2012-04-01

    Full Text Available Cognitive and affective processes vary over the course of the 24 hour day. Time of day dependent changes in human cognition are modulated by an internal circadian timekeeping system with a near-24-hour period. The human circadian timekeeping system interacts with sleep-wakefulness regulatory processes to modulate brain arousal, neurocognitive and affective function. Brain arousal is regulated by ascending brain stem, basal forebrain and hypothalamic arousal systems and inhibition or disruption of these systems reduces brain arousal, impairs cognition, and promotes sleep. The internal circadian timekeeping system modulates cognition and affective function by projections from the master circadian clock, located in the hypothalamic suprachiasmatic nuclei, to arousal and sleep systems and via clock gene oscillations in brain tissues. Understanding the basic principles of circadian and wakefulness-sleep physiology can help to recognize how the circadian system modulates human cognition and influences learning, memory and emotion. Developmental changes in sleep and circadian processes and circadian misalignment in circadian rhythm sleep disorders have important implications for learning, memory and emotion. Overall, when wakefulness occurs at appropriate internal biological times, circadian clockwork benefits human cognitive and emotion function throughout the lifespan. Yet, when wakefulness occurs at inappropriate biological times because of environmental pressures (e.g., early school start times, long work hours that include work at night, shift work, jet lag or because of circadian rhythm sleep disorders, the resulting misalignment between circadian and wakefulness-sleep physiology leads to impaired cognitive performance, learning, emotion, and safety.

  15. Circadian timekeeping : from basic clock function to implications for health

    NARCIS (Netherlands)

    Lucassen, Eliane Alinda

    2016-01-01

    In modern society, circadian rhythms and sleep are often disturbed, which may negatively affect health. This thesis examines these associations and focuses on the basic functioning of sleep and the circadian system in mice and in humans. Circadian rhythms are orchestrated by ~20,000 neurons in the

  16. Circadian aspects of post-operative morbidity and mortality

    DEFF Research Database (Denmark)

    Kvaslerud, T.; Hansen, M.V.; Rosenberg, J.;

    2010-01-01

    concerning post-operative circadian disturbances. We also present the literature concerning circadian variation in post-operative morbidity and mortality. PubMed and the Cochrane database were searched for papers using a combination of 'circadian,' 'surgery,' 'post-operative,' 'mortality' and 'morbidity...

  17. Accessorizing the human mitochondrial transcription machinery.

    Science.gov (United States)

    Bestwick, Megan L; Shadel, Gerald S

    2013-06-01

    The human genome comprises large chromosomes in the nucleus and mitochondrial DNA (mtDNA) housed in the dynamic mitochondrial network. Human cells contain up to thousands of copies of the double-stranded, circular mtDNA molecule that encodes essential subunits of the oxidative phosphorylation complexes and the rRNAs and tRNAs needed to translate these in the organelle matrix. Transcription of human mtDNA is directed by a single-subunit RNA polymerase, POLRMT, which requires two primary transcription factors, TFB2M (transcription factor B2, mitochondrial) and TFAM (transcription factor A, mitochondrial), to achieve basal regulation of the system. Here, we review recent advances in understanding the structure and function of the primary human transcription machinery and the other factors that facilitate steps in transcription beyond initiation and provide more intricate control over the system. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. The SNARE machinery in mast cell secretion

    Directory of Open Access Journals (Sweden)

    Axel eLorentz

    2012-06-01

    Full Text Available Mast cells are known as inflammatory cells which exert their functions in allergic and anaphylactic reactions by secretion of numerous inflammatory mediators. During an allergic response, the high-affinity IgE receptor, FcεRI, becomes cross-linked by receptor-bound IgE and antigen resulting in immediate release of pre-synthesized mediators – stored in granules – as well as in de novo synthesis of various mediators like cytokines and chemokines. Soluble N-ethylmaleimide-Sensitive Factor (NSF Attachment Protein (SNAP Receptors (SNARE proteins were found to play a central role in regulating membrane fusion events during exocytosis. In addition, several accessory regulators like Munc13, Munc18, Rab GTPases, SCAMPs, complexins or synaptotagmins were found to be involved in membrane fusion. In this review we summarize our current knowledge about the SNARE machinery and its mechanism of action in mast cell secretion.

  19. Numerical Noise Prediction in Fluid Machinery

    Institute of Scientific and Technical Information of China (English)

    Iris PANTLE; Franco MAGAGNATO; Martin GABI

    2005-01-01

    Numerical methods successively became important in the design and optimization of fluid machinery. However,as noise emission is considered, one can hardly find standardized prediction methods combining flow and acoustical optimization. Several numerical field methods for sound calculations have been developed. Due to the complexity of the considered flow, approaches must be chosen to avoid exhaustive computing. In this contribution the noise of a simple propeller is investigated. The configurations of the calculations comply with an existing experimental setup chosen for evaluation. The used in-house CFD solver SPARC contains an acoustic module based on Ffowcs Williams-Hawkings Acoustic Analogy. From the flow results of the time dependent Large Eddy Simulation the time dependent acoustic sources are extracted and given to the acoustic module where relevant sound pressure levels are calculated. The difficulties, which arise while proceeding from open to closed rotors and from gas to liquid are discussed.

  20. Photoperiod sensitivity of the Arabidopsis circadian clock is tissue-specific.

    Science.gov (United States)

    Shimizu, Hanako; Araki, Takashi; Endo, Motomu

    2015-01-01

    Tissue-specific functions of the circadian clock in Arabidopsis have recently been revealed. The vasculature clock shows distinctive gene expression profiles compared to the clock in other tissues under light-dark cycles. However, it has not yet been established whether the vasculature clock also shows unique gene expression patterns that correlate with temperature cycles, another important environmental cue. Here, we detected diel phase of TIMING OF CAB EXPRESSION 1 (TOC1) expression in the vasculature and whole leaf under long-day light-dark cycles and temperature cycles. We found that the vasculature clock had advanced TOC1 phase under light-dark cycles but not under temperature cycles, suggesting that the vasculature clock has lower sensitivity against temperature signals. Furthermore, the phase advancement of TOC1 was seen only under long-day condition but not under short-day condition. These results support our previous conclusion that the circadian clock in vasculature preferentially senses photoperiodic signals.

  1. Questing for circadian dependence in ST-segment-elevation acute myocardial infarction: A multicentric and multiethnic study

    KAUST Repository

    Ammirati, Enrico

    2013-05-09

    Rationale: Four monocentric studies reported that circadian rhythms can affect left ventricular infarct size after ST-segment-elevation acute myocardial infarction (STEMI). Objective: To further validate the circadian dependence of infarct size after STEMI in a multicentric and multiethnic population. Methods and Results: We analyzed a prospective cohort of subjects with first STEMI from the First Acute Myocardial Infarction study that enrolled 1099 patients (ischemic time <6 hours) in Italy, Scotland, and China. We confirmed a circadian variation of STEMI incidence with an increased morning incidence (from 6:00 am till noon). We investigated the presence of circadian dependence of infarct size plotting the peak creatine kinase against time onset of ischemia. In addition, we studied the patients from the 3 countries separately, including 624 Italians; all patients were treated with percutaneous coronary intervention. We adopted several levels of analysis with different inclusion criteria consistent with previous studies. In all the analyses, we did not find a clear-cut circadian dependence of infarct size after STEMI. Conclusions: Although the circadian dependence of infarct size supported by previous studies poses an intriguing hypothesis, we were unable to converge toward their conclusions in a multicentric and multiethnic setting. Parameters that vary as a function of latitude could potentially obscure the circadian variations observed in monocentric studies. We believe that, to assess whether circadian rhythms can affect the infarct size, future study design should not only include larger samples but also aim to untangle the molecular time-dynamic mechanisms underlying such a relation. © 2013 American Heart Association, Inc.

  2. The Clock Gene Rev-Erbα Regulates Methamphetamine Actions on Circadian Timekeeping in the Mouse Brain.

    Science.gov (United States)

    Salaberry, Nora L; Mateo, Maria; Mendoza, Jorge

    2017-09-01

    Circadian rhythms are strongly affected by drugs. In rodents, chronic methamphetamine (METH) intake changes circadian activity rhythms, mainly by altering light synchronization that generates the expression of a free-running rhythm with a period longer than 24 h and a second behavioral component that is independent of the main suprachiasmatic (SCN) clock. Although a number of clock genes do not appear to be involved in the effects of METH on circadian behavior, the molecular clockwork controlling these changes is still unclear. Therefore, we investigated the role of the clock gene Rev-Erbα in METH-induced behavioral and molecular responses using knockout mice and their wild-type littermates. Chronic intake of METH alters period circadian behavior of wild-type mice. However, in mice lacking the clock gene Rev-Erbα METH had no effect on their behavioral rhythms. Furthermore, PER2 bioluminescence rhythms in two extra-SCN brain oscillators, the dorsomedial hypothalamus and the habenula, were altered by METH in wild type but not in KO mice. Together, the present results implicate Rev-Erbα in the modulation of the circadian responses to METH and may provide a better comprehension into the mechanisms underlying circadian alterations provoked by drug addiction.

  3. USP7 and TDP-43: Pleiotropic Regulation of Cryptochrome Protein Stability Paces the Oscillation of the Mammalian Circadian Clock.

    Directory of Open Access Journals (Sweden)

    Arisa Hirano

    Full Text Available Mammalian Cryptochromes, CRY1 and CRY2, function as principal regulators of a transcription-translation-based negative feedback loop underlying the mammalian circadian clockwork. An F-box protein, FBXL3, promotes ubiquitination and degradation of CRYs, while FBXL21, the closest paralog of FBXL3, ubiquitinates CRYs but leads to stabilization of CRYs. Fbxl3 knockout extremely lengthened the circadian period, and deletion of Fbxl21 gene in Fbxl3-deficient mice partially rescued the period-lengthening phenotype, suggesting a key role of CRY protein stability for maintenance of the circadian periodicity. Here, we employed a proteomics strategy to explore regulators for the protein stability of CRYs. We found that ubiquitin-specific protease 7 (USP7 also known as HAUSP associates with CRY1 and CRY2 and stabilizes CRYs through deubiquitination. Treatment with USP7-specific inhibitor or Usp7 knockdown shortened the circadian period of the cellular rhythm. We identified another CRYs-interacting protein, TAR DNA binding protein 43 (TDP-43, an RNA-binding protein. TDP-43 stabilized CRY1 and CRY2, and its knockdown also shortened the circadian period in cultured cells. The present study identified USP7 and TDP-43 as the regulators of CRY1 and CRY2, underscoring the significance of the stability control process of CRY proteins for period determination in the mammalian circadian clockwork.

  4. Mitogen-activated protein kinase is a functional component of the autonomous circadian system in the suprachiasmatic nucleus.

    Science.gov (United States)

    Akashi, Makoto; Hayasaka, Naoto; Yamazaki, Shin; Node, Koichi

    2008-04-30

    The suprachiasmatic nucleus (SCN) is the master circadian pacemaker driving behavioral and physiological rhythms in mammals. Circadian activation of mitogen-activated protein kinase [MAPK; also known as ERK (extracellular signal-regulated kinase)] is observed in vivo in the SCN under constant darkness, although the biological significance of this remains unclear. To elucidate this question, we first examined whether MAPK was autonomously activated in ex vivo SCN slices. Moreover, we investigated the effect of MAPK inhibition on circadian clock gene expression and neuronal firing rhythms using SCN-slice culture systems. We show herein that MAPK is autonomously activated in the SCN, and our data demonstrate that inhibition of the MAPK activity results in dampened rhythms and reduced basal levels in circadian clock gene expression at the SCN single-neuron level. Furthermore, MAPK inhibition attenuates autonomous circadian neuronal firing rhythms in the SCN. Thus, our data suggest that light-independent MAPK activity contributes to the robustness of the SCN autonomous circadian system.

  5. Optimal Implementations for Reliable Circadian Clocks

    Science.gov (United States)

    Hasegawa, Yoshihiko; Arita, Masanori

    2014-09-01

    Circadian rhythms are acquired through evolution to increase the chances for survival through synchronizing with the daylight cycle. Reliable synchronization is realized through two trade-off properties: regularity to keep time precisely, and entrainability to synchronize the internal time with daylight. We find by using a phase model with multiple inputs that achieving the maximal limit of regularity and entrainability entails many inherent features of the circadian mechanism. At the molecular level, we demonstrate the role sharing of two light inputs, phase advance and delay, as is well observed in mammals. At the behavioral level, the optimal phase-response curve inevitably contains a dead zone, a time during which light pulses neither advance nor delay the clock. We reproduce the results of phase-controlling experiments entrained by two types of periodic light pulses. Our results indicate that circadian clocks are designed optimally for reliable clockwork through evolution.

  6. Oxytocin in the circadian timing of birth.

    Directory of Open Access Journals (Sweden)

    Jeffrey Roizen

    Full Text Available BACKGROUND: The molecular components determining the timing for birth remain an incompletely characterized aspect of reproduction, with important conceptual and therapeutic ramifications for management of preterm, post-term and arrested labor. METHODOLOGY/PRINCIPAL FINDINGS: To test the hypothesis that oxytocin mediates circadian regulation of birth, we evaluated parturition timing following shifts in light cycles in oxytocin (OT-deficient mice. We find that, in contrast to wild type mice that do not shift the timing of birth following a 6-h advance or delay in the light cycle, OT-deficient mice delivered at random times of day. Moreover, shifts in the light-dark cycle of gravid wild type mice have little impact on the pattern of circadian oxytocin release. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate oxytocin plays a critical role in minimizing labor disruption due to circadian clock resetting.

  7. Circadian clocks and life-history related traits: is pupation height affected by circadian organization in Drosophila melanogaster?

    Indian Academy of Sciences (India)

    Dhanashree A. Paranjpe; D. Anitha; Vijay Kumar Sharma; Amitabh Joshi

    2004-04-01

    In D. melanogaster, the observation of greater pupation height under constant darkness than under constant light has been explained by the hypothesis that light has an inhibitory effect on larval wandering behaviour, preventing larvae from crawling higher up the walls of culture vials prior to pupation. If this is the only role of light in affecting pupation height, then various light : dark regimes would be predicted to yield pupation heights intermediate between those seen in constant light and constant darkness. We tested this hypothesis by measuring pupation height under various light : dark regimes in four laboratory populations of Drosophila melanogaster. Pupation height was the greatest in constant darkness, intermediate in constant light, and the least in a light / dark regime of LD 14:14 h. The results clearly suggest that there is more to light regime effects on pupation height than mere behavioural inhibition of wandering larvae, and that circadian organization may play some role in determining pupation height, although the details of this role are not yet clear. We briefly discuss these results in the context of the possible involvement of circadian clocks in life-history evolution.

  8. Mutual antagonism between circadian protein period 2 and hepatitis C virus replication in hepatocytes.

    Directory of Open Access Journals (Sweden)

    Giorgia Benegiamo

    Full Text Available BACKGROUND: Hepatitis C virus (HCV infects approximately 3% of the world population and is the leading cause of liver disease, impacting hepatocyte metabolism, depending on virus genotype. Hepatic metabolic functions show rhythmic fluctuations with 24-h periodicity (circadian, driven by molecular clockworks ticking through translational-transcriptional feedback loops, operated by a set of genes, called clock genes, encoding circadian proteins. Disruption of biologic clocks is implicated in a variety of disorders including fatty liver disease, obesity and diabetes. The relation between HCV replication and the circadian clock is unknown. METHODS: We investigated the relationship between HCV core infection and viral replication and the expression of clock genes (Rev-Erbα, Rorα, ARNTL, ARNTL2, CLOCK, PER1, PER2, PER3, CRY1 and CRY2 in two cellular models, the Huh-7 cells transiently expressing the HCV core protein genotypes 1b or 3a, and the OR6 cells stably harboring the full-length hepatitis C genotype 1b replicon, and in human liver biopsies, using qRT-PCR, immunoblotting, luciferase assays and immunohistochemistry. RESULTS: In Huh-7 cells expressing the HCV core protein genotype 1b, but not 3a, and in OR6 cells, transcript and protein levels of PER2 and CRY2 were downregulated. Overexpression of PER2 led to a consistent decrease in HCV RNA replicating levels and restoration of altered expression pattern of a subset of interferon stimulated genes (ISGs in OR6 cells. Furthermore, in liver biopsies from HCV genotype 1b infected patients, PER2 was markedly localized to the nucleus, consistent with an auto-inhibitory transcriptional feedback loop. CONCLUSIONS: HCV can modulate hepatic clock gene machinery, and the circadian protein PER2 counteracts viral replication. Further understanding of circadian regulation of HCV replication and rhythmic patterns of host-hosted relationship may improve the effectiveness of HCV antiviral therapy. This would

  9. Circadian polymorphisms in night owls, in bipolars, and in non-24-hour sleep cycles.

    Science.gov (United States)

    Kripke, Daniel F; Klimecki, Walter T; Nievergelt, Caroline M; Rex, Katharine M; Murray, Sarah S; Shekhtman, Tatyana; Tranah, Gregory J; Loving, Richard T; Lee, Heon-Jeong; Rhee, Min Kyu; Shadan, Farhad F; Poceta, J Steven; Jamil, Shazia M; Kline, Lawrence E; Kelsoe, John R

    2014-10-01

    People called night owls habitually have late bedtimes and late times of arising, sometimes suffering a heritable circadian disturbance called delayed sleep phase syndrome (DSPS). Those with DSPS, those with more severe progressively-late non-24-hour sleep-wake cycles, and those with bipolar disorder may share genetic tendencies for slowed or delayed circadian cycles. We searched for polymorphisms associated with DSPS in a case-control study of DSPS research participants and a separate study of Sleep Center patients undergoing polysomnography. In 45 participants, we resequenced portions of 15 circadian genes to identify unknown polymorphisms that might be associated with DSPS, non-24-hour rhythms, or bipolar comorbidities. We then genotyped single nucleotide polymorphisms (SNPs) in both larger samples, using Illumina Golden Gate assays. Associations of SNPs with the DSPS phenotype and with the morningness-eveningness parametric phenotype were computed for both samples, then combined for meta-analyses. Delayed sleep and "eveningness" were inversely associated with loci in circadian genes NFIL3 (rs2482705) and RORC (rs3828057). A group of haplotypes overlapping BHLHE40 was associated with non-24-hour sleep-wake cycles, and less robustly, with delayed sleep and bipolar disorder (e.g., rs34883305, rs34870629, rs74439275, and rs3750275 were associated with n=37, p=4.58E-09, Bonferroni p=2.95E-06). Bright light and melatonin can palliate circadian disorders, and genetics may clarify the underlying circadian photoperiodic mechanisms. After further replication and identification of the causal polymorphisms, these findings may point to future treatments for DSPS, non-24-hour rhythms, and possibly bipolar disorder or depression.

  10. Machinery failure analysis and troubleshooting practical machinery management for process plants

    CERN Document Server

    Bloch, Heinz P

    2012-01-01

    Solve the machinery failure problems costing you time and money with this classic, comprehensive guide to analysis and troubleshooting  Provides detailed, complete and accurate information on anticipating risk of component failure and avoiding equipment downtime Includes numerous photographs of failed parts to ensure you are familiar with the visual evidence you need to recognize Covers proven approaches to failure definition and offers failure identification and analysis methods that can be applied to virtually all problem situations Demonstr

  11. The circadian variation of premature atrial contractions

    DEFF Research Database (Denmark)

    Larsen, Bjørn Strøier; Kumarathurai, Preman; Nielsen, Olav W

    2016-01-01

    AIMS: The aim of the study was to assess a possible circadian variation of premature atrial contractions (PACs) in a community-based population and to determine if the daily variation could be used to assess a more vulnerable period of PACs in predicting later incidence of atrial fibrillation (AF...... variation in heart rate. After adjusting for relevant risk factors, the risk of AF was equal in all time intervals throughout the day. CONCLUSION: Premature atrial contractions showed a circadian variation in subjects with frequent PACs. No specific time interval of the day was more predictive of AF than...

  12. Plant circadian clocks increase photosynthesis, growth, survival, and competitive advantage.

    Science.gov (United States)

    Dodd, Antony N; Salathia, Neeraj; Hall, Anthony; Kévei, Eva; Tóth, Réka; Nagy, Ferenc; Hibberd, Julian M; Millar, Andrew J; Webb, Alex A R

    2005-07-22

    Circadian clocks are believed to confer an advantage to plants, but the nature of that advantage has been unknown. We show that a substantial photosynthetic advantage is conferred by correct matching of the circadian clock period with that of the external light-dark cycle. In wild type and in long- and short-circadian period mutants of Arabidopsis thaliana, plants with a clock period matched to the environment contain more chlorophyll, fix more carbon, grow faster, and survive better than plants with circadian periods differing from their environment. This explains why plants gain advantage from circadian control.

  13. Immunity's fourth dimension: approaching the circadian-immune connection.

    Science.gov (United States)

    Arjona, Alvaro; Silver, Adam C; Walker, Wendy E; Fikrig, Erol

    2012-12-01

    The circadian system ensures the generation and maintenance of self-sustained ~24-h rhythms in physiology that are linked to internal and environmental changes. In mammals, daily variations in light intensity and other cues are integrated by a hypothalamic master clock that conveys circadian information to peripheral molecular clocks that orchestrate physiology. Multiple immune parameters also vary throughout the day and disruption of circadian homeostasis is associated with immune-related disease. Here, we discuss the molecular links between the circadian and immune systems and examine their outputs and disease implications. Understanding the mechanisms that underlie circadian-immune crosstalk may prove valuable for devising novel prophylactic and therapeutic interventions.

  14. Modelling of intercellular synchronization in the Drosophila circadian clock

    Institute of Scientific and Technical Information of China (English)

    Wang Jun-Wei; Chen Ai-Min; Zhang Jia-Jun; Yuan Zhan-Jiang; Zhou Tian-Shou

    2009-01-01

    In circadian rhythm generation, intercellular signaling factors are shown to play a crucial role in both sustaining intrinsic cellular rhythmicity and acquiring collective behaviours across a population of circadian neurons. However, the physical mechanism behind their role remains to be fully understood. In this paper, we propose an indirectly coupled multicellular model for the synchronization of Drosophila circadian oscillators combining both intracellular and intercellular dynamics. By simulating different experimental conditions, we find that such an indirect coupling way can synchronize both heterogeneous self-sustained circadian neurons and heterogeneous mutational damped circadian neurons. Moreover, they can also be entrained to ambient light-dark (LD) cycles depending on intercellular signaling.

  15. Digital clocks: simple Boolean models can quantitatively describe circadian systems.

    Science.gov (United States)

    Akman, Ozgur E; Watterson, Steven; Parton, Andrew; Binns, Nigel; Millar, Andrew J; Ghazal, Peter

    2012-09-07

    The gene networks that comprise the circadian clock modulate biological function across a range of scales, from gene expression to performance and adaptive behaviour. The clock functions by generating endogenous rhythms that can be entrained to the external 24-h day-night cycle, enabling organisms to optimally time biochemical processes relative to dawn and dusk. In recent years, computational models based on differential equations have become useful tools for dissecting and quantifying the complex regulatory relationships underlying the clock's oscillatory dynamics. However, optimizing the large parameter sets characteristic of these models places intense demands on both computational and experimental resources, limiting the scope of in silico studies. Here, we develop an approach based on Boolean logic that dramatically reduces the parametrization, making the state and parameter spaces finite and tractable. We introduce efficient methods for fitting Boolean models to molecular data, successfully demonstrating their application to synthetic time courses generated by a number of established clock models, as well as experimental expression levels measured using luciferase imaging. Our results indicate that despite their relative simplicity, logic models can (i) simulate circadian oscillations with the correct, experimentally observed phase relationships among genes and (ii) flexibly entrain to light stimuli, reproducing the complex responses to variations in daylength generated by more detailed differential equation formulations. Our work also demonstrates that logic models have sufficient predictive power to identify optimal regulatory structures from experimental data. By presenting the first Boolean models of circadian circuits together with general techniques for their optimization, we hope to establish a new framework for the systematic modelling of more complex clocks, as well as other circuits with different qualitative dynamics. In particular, we anticipate

  16. Industrial Machinery Maintenance and Repair. Florida Vocational Program Guide.

    Science.gov (United States)

    University of South Florida, Tampa. Dept. of Adult and Vocational Education.

    This vocational program guide is intended to assist in the organization, operation, and evaluation of a program in industrial machinery maintenance and repair in school districts, area vocational centers, and community colleges. The following topics are covered: job duties of millwrights, maintenance mechanics, and machinery erectors; program…

  17. Stepwise evolution of the Sec machinery in Proteobacteria

    NARCIS (Netherlands)

    van der Sluis, EO; Driessen, AJM; Sluis, Eli O. van der

    2006-01-01

    The Sec machinery facilitates the translocation of proteins across and into biological membranes. In several of the Proteobacteria, this machinery contains accessory features that are not present in any other bacterial division. The genomic distribution of these features in the context of bacterial

  18. Recession Hits China’s Textile Machinery Markets

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    China’s textile machinery industry saw a continued decline intotaI profit and a hefty slump in imports and exports in the first twomonths this year.Analysts anticipated a continued weakening ofmomentum for China’s textile machinery markets owing to weakerconsumer spending and easing export growth.

  19. ITALIAN TEXTILE MACHINERY WORKSHOP IN SUZHOU(CHINA)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The Association of Italian Textile Machinery Manufacturers (ACIMIT)and the Italian Trade Commission(ICE)held a technical workshop on Italian textile machinery for the production of technical textiles and nonwovens in China.The workshop occurred in Suzhou(Juangsu Province),on May 24th-25th,2007.

  20. 46 CFR 282.23 - Hull and machinery insurance.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 8 2010-10-01 2010-10-01 false Hull and machinery insurance. 282.23 Section 282.23... COMMERCE OF THE UNITED STATES Calculation of Subsidy Rates § 282.23 Hull and machinery insurance. (a) Subsidy items. The fair and reasonable net premium costs (including stamp taxes) of hull and...

  1. 46 CFR 111.103-9 - Machinery stop stations.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Machinery stop stations. 111.103-9 Section 111.103-9 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Remote Stopping Systems § 111.103-9 Machinery stop stations. (a) Each forced...

  2. Occupational incidents with self-propelled machinery in Austrian agriculture.

    Science.gov (United States)

    Mayrhofer, Hannes; Quendler, Elisabeth; Boxberger, Josef

    2013-01-01

    Tractors, self-propelled harvesting machinery, and material handling machinery are the most commonly used self-propelled machineries in Austrian agriculture, and they have similarities in main accident scenarios. Statistical data of all occupational incidents with these machines reported between 2008 and 2010 were analyzed to obtain information about the circumstances of the incidents, and about the victims and their work environments. Criteria of recognized occupational incidents provided by the Austrian Social Insurance Institution for Farmers were analyzed according to machinery category by means of cross-tabulation and chi-square tests. The results were discussed and evaluated in the context of the literature. The results of the analysis of the databases show that 786 occupational incidents with tractors, self-propelled harvesting machinery, and material handling machinery occurred in Austrian agriculture between 2008 and 2010. There were 231 occupational incidents in 2008; the number rose to 268 in 2009 and to 286 in 2010. A total of 41 incidents were fatal. For the machinery categories analyzed, the majority of injured victims were male, older than 40 years, Austrian citizens, and managers of a mixed-agricultural farm. A large number of the incidents occurred in all machinery categories by loss of control during operating a vehicle.

  3. Evolution and diversification of the basal transcription machinery.

    Science.gov (United States)

    Duttke, Sascha H C

    2015-03-01

    Transcription initiation was once thought to be regulated primarily by sequence-specific transcription factors with the basal transcription machinery being largely invariant. Gradually it became apparent that the basal transcription machinery greatly diversified during evolution and new studies now demonstrate that diversification of the TATA-binding protein (TBP) family yielded specialized and largely independent transcription systems.

  4. 46 CFR 119.465 - Ventilation of spaces containing diesel machinery.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Ventilation of spaces containing diesel machinery. 119... MACHINERY INSTALLATION Specific Machinery Requirements § 119.465 Ventilation of spaces containing diesel machinery. (a) A space containing diesel machinery must be fitted with adequate means, such as...

  5. Dynamic organization of the mitochondrial protein import machinery.

    Science.gov (United States)

    Straub, Sebastian P; Stiller, Sebastian B; Wiedemann, Nils; Pfanner, Nikolaus

    2016-11-01

    Mitochondria contain elaborate machineries for the import of precursor proteins from the cytosol. The translocase of the outer mitochondrial membrane (TOM) performs the initial import of precursor proteins and transfers the precursors to downstream translocases, including the presequence translocase and the carrier translocase of the inner membrane, the mitochondrial import and assembly machinery of the intermembrane space, and the sorting and assembly machinery of the outer membrane. Although the protein translocases can function as separate entities in vitro, recent studies revealed a close and dynamic cooperation of the protein import machineries to facilitate efficient transfer of precursor proteins in vivo. In addition, protein translocases were found to transiently interact with distinct machineries that function in the respiratory chain or in the maintenance of mitochondrial membrane architecture. Mitochondrial protein import is embedded in a regulatory network that ensures protein biogenesis, membrane dynamics, bioenergetic activity and quality control.

  6. Light pulses administered during the circadian dark phase alter expression of cell cycle associated transcripts in mouse brain.

    Science.gov (United States)

    Ben-Shlomo, R; Kyriacou, C P

    2010-02-01

    The circadian mode of cell division has been known for more than a century, but the association between circadian rhythms and mitosis is not yet clear. Synchronization of circadian oscillators with the outside world is achieved because light, or other external temporal cues, have acute effects on the levels of the clock's molecular components. Thus, an important question is whether environmental signals also affect transcription levels of cell machinery genes in a similar manner? In a microarray analysis, we have tested the influence of light pulses on the expression of transcripts in the mouse brain. Light pulses consistently affect transcription levels of genes that are essential and directly control the cell cycle mechanism, as well as levels of genes that are associated with the various cell cycle checkpoints. The changes in the levels and the direction of these changes could possibly lead to cell cycle arrest. We also found consistent changes in transcription levels of genes that are associated with tumorigenesis and are directly implicated with enhanced proliferation and metastasis.

  7. Circadian and Circalunar Clock Interactions in a Marine Annelid

    Directory of Open Access Journals (Sweden)

    Juliane Zantke

    2013-10-01

    Full Text Available Life is controlled by multiple rhythms. Although the interaction of the daily (circadian clock with environmental stimuli, such as light, is well documented, its relationship to endogenous clocks with other periods is little understood. We establish that the marine worm Platynereis dumerilii possesses endogenous circadian and circalunar (monthly clocks and characterize their interactions. The RNAs of likely core circadian oscillator genes localize to a distinct nucleus of the worm’s forebrain. The worm’s forebrain also harbors a circalunar clock entrained by nocturnal light. This monthly clock regulates maturation and persists even when circadian clock oscillations are disrupted by the inhibition of casein kinase 1δ/ε. Both circadian and circalunar clocks converge on the regulation of transcript levels. Furthermore, the circalunar clock changes the period and power of circadian behavior, although the period length of the daily transcriptional oscillations remains unaltered. We conclude that a second endogenous noncircadian clock can influence circadian clock function.

  8. The Pentose Phosphate Pathway Regulates the Circadian Clock.

    Science.gov (United States)

    Rey, Guillaume; Valekunja, Utham K; Feeney, Kevin A; Wulund, Lisa; Milev, Nikolay B; Stangherlin, Alessandra; Ansel-Bollepalli, Laura; Velagapudi, Vidya; O'Neill, John S; Reddy, Akhilesh B

    2016-09-13

    The circadian clock is a ubiquitous timekeeping system that organizes the behavior and physiology of organisms over the day and night. Current models rely on transcriptional networks that coordinate circadian gene expression of thousands of transcripts. However, recent studies have uncovered phylogenetically conserved redox rhythms that can occur independently of transcriptional cycles. Here we identify the pentose phosphate pathway (PPP), a critical source of the redox cofactor NADPH, as an important regulator of redox and transcriptional oscillations. Our results show that genetic and pharmacological inhibition of the PPP prolongs the period of circadian rhythms in human cells, mouse tissues, and fruit flies. These metabolic manipulations also cause a remodeling of circadian gene expression programs that involves the circadian transcription factors BMAL1 and CLOCK, and the redox-sensitive transcription factor NRF2. Thus, the PPP regulates circadian rhythms via NADPH metabolism, suggesting a pivotal role for NADPH availability in circadian timekeeping.

  9. The interactions between the circadian clock and primary metabolism.

    Science.gov (United States)

    Farré, Eva M; Weise, Sean E

    2012-06-01

    Primary metabolism in plants is tightly regulated by environmental factors such as light and nutrient availability at multiple levels. The circadian clock is a self-sustained endogenous oscillator that enables organisms to predict daily and seasonal changes. The regulation of primary metabolism by the circadian clock has been proposed to explain the importance of circadian rhythms in plant growth and survival. Recent transcriptomic and metabolomic analyses indicate a wide spread circadian regulation of different metabolic processes. We review evidence of circadian regulation of pathways in primary metabolism, discuss the challenges faced for discerning the mechanisms regulating circadian metabolic oscillations and present recent evidence of regulation of the circadian clock by metabolites. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Regulation of behavioral circadian rhythms and clock protein PER1 by the deubiquitinating enzyme USP2

    Directory of Open Access Journals (Sweden)

    Yaoming Yang

    2012-06-01

    Endogenous 24-hour rhythms are generated by circadian clocks located in most tissues. The molecular clock mechanism is based on feedback loops involving clock genes and their protein products. Post-translational modifications, including ubiquitination, are important for regulating the clock feedback mechanism. Previous work has focused on the role of ubiquitin ligases in the clock mechanism. Here we show a role for the rhythmically-expressed deubiquitinating enzyme ubiquitin specific peptidase 2 (USP2 in clock function. Mice with a deletion of the Usp2 gene (Usp2 KO display a longer free-running period of locomotor activity rhythms and altered responses of the clock to light. This was associated with altered expression of clock genes in synchronized Usp2 KO mouse embryonic fibroblasts and increased levels of clock protein PERIOD1 (PER1. USP2 can be coimmunoprecipitated with several clock proteins but directly interacts specifically with PER1 and deubiquitinates it. Interestingly, this deubiquitination does not alter PER1 stability. Taken together, our results identify USP2 as a new core component of the clock machinery and demonstrate a role for deubiquitination in the regulation of the circadian clock, both at the level of the core pacemaker and its response to external cues.

  11. Characteristics and concepts of dynamic hub proteins in DNA processing machinery from studies of RPA.

    Science.gov (United States)

    Sugitani, Norie; Chazin, Walter J

    2015-03-01

    DNA replication, damage response and repair require the coordinated action of multi-domain proteins operating within dynamic multi-protein machines that act upon the DNA substrate. These modular proteins contain flexible linkers of various lengths, which enable changes in the spatial distribution of the globular domains (architecture) that harbor their essential biochemical functions. This mobile architecture is uniquely suited to follow the evolving substrate landscape present over the course of the specific process performed by the multi-protein machinery. A fundamental advance in understanding of protein machinery is the realization of the pervasive role of dynamics. Not only is the machine undergoing dynamic transformations, but the proteins themselves are flexible and constantly adapting to the progression through the steps of the overall process. Within this dynamic context the activity of the constituent proteins must be coordinated, a role typically played by hub proteins. A number of important characteristics of modular proteins and concepts about the operation of dynamic machinery have been discerned. These provide the underlying basis for the action of the machinery that reads DNA, and responds to and repairs DNA damage. Here, we introduce a number of key characteristics and concepts, including the modularity of the proteins, linkage of weak binding sites, direct competition between sites, and allostery, using the well recognized hub protein replication protein A (RPA).

  12. Effect of amyloids on the vesicular machinery: implications for somatic neurotransmission.

    Science.gov (United States)

    Das, Anand Kant; Pandit, Rucha; Maiti, Sudipta

    2015-07-01

    Certain neurodegenerative diseases are thought to be initiated by the aggregation of amyloidogenic proteins. However, the mechanism underlying toxicity remains obscure. Most of the suggested mechanisms are generic in nature and do not directly explain the neuron-type specific lesions observed in many of these diseases. Some recent reports suggest that the toxic aggregates impair the synaptic vesicular machinery. This may lead to an understanding of the neuron-type specificity observed in these diseases. A disruption of the vesicular machinery can also be deleterious for extra-synaptic, especially somatic, neurotransmission (common in serotonergic and dopaminergic systems which are specifically affected in Alzheimer's disease (AD) and Parkinson's disease (PD), respectively), though this relationship has remained unexplored. In this review, we discuss amyloid-induced damage to the neurotransmitter vesicular machinery, with an eye on the possible implications for somatic exocytosis. We argue that the larger size of the system, and the availability of multi-photon microscopy techniques for directly visualizing monoamines, make the somatic exocytosis machinery a more tractable model for understanding the effect of amyloids on all types of vesicular neurotransmission. Indeed, exploring this neglected connection may not just be important, it may be a more fruitful route for understanding AD and PD.

  13. The peroxisomal protein import machinery displays a preference for monomeric substrates.

    Science.gov (United States)

    Freitas, Marta O; Francisco, Tânia; Rodrigues, Tony A; Lismont, Celien; Domingues, Pedro; Pinto, Manuel P; Grou, Cláudia P; Fransen, Marc; Azevedo, Jorge E

    2015-04-01

    Peroxisomal matrix proteins are synthesized on cytosolic ribosomes and transported by the shuttling receptor PEX5 to the peroxisomal membrane docking/translocation machinery, where they are translocated into the organelle matrix. Under certain experimental conditions this protein import machinery has the remarkable capacity to accept already oligomerized proteins, a property that has heavily influenced current models on the mechanism of peroxisomal protein import. However, whether or not oligomeric proteins are really the best and most frequent clients of this machinery remain unclear. In this work, we present three lines of evidence suggesting that the peroxisomal import machinery displays a preference for monomeric proteins. First, in agreement with previous findings on catalase, we show that PEX5 binds newly synthesized (monomeric) acyl-CoA oxidase 1 (ACOX1) and urate oxidase (UOX), potently inhibiting their oligomerization. Second, in vitro import experiments suggest that monomeric ACOX1 and UOX are better peroxisomal import substrates than the corresponding oligomeric forms. Finally, we provide data strongly suggesting that although ACOX1 lacking a peroxisomal targeting signal can be imported into peroxisomes when co-expressed with ACOX1 containing its targeting signal, this import pathway is inefficient.

  14. Robustness of circadian clocks to daylight fluctuations: hints from the picoeucaryote Ostreococcus tauri.

    Directory of Open Access Journals (Sweden)

    Quentin Thommen

    Full Text Available The development of systemic approaches in biology has put emphasis on identifying genetic modules whose behavior can be modeled accurately so as to gain insight into their structure and function. However, most gene circuits in a cell are under control of external signals and thus, quantitative agreement between experimental data and a mathematical model is difficult. Circadian biology has been one notable exception: quantitative models of the internal clock that orchestrates biological processes over the 24-hour diurnal cycle have been constructed for a few organisms, from cyanobacteria to plants and mammals. In most cases, a complex architecture with interlocked feedback loops has been evidenced. Here we present the first modeling results for the circadian clock of the green unicellular alga Ostreococcus tauri. Two plant-like clock genes have been shown to play a central role in the Ostreococcus clock. We find that their expression time profiles can be accurately reproduced by a minimal model of a two-gene transcriptional feedback loop. Remarkably, best adjustment of data recorded under light/dark alternation is obtained when assuming that the oscillator is not coupled to the diurnal cycle. This suggests that coupling to light is confined to specific time intervals and has no dynamical effect when the oscillator is entrained by the diurnal cycle. This intriguing property may reflect a strategy to minimize the impact of fluctuations in daylight intensity on the core circadian oscillator, a type of perturbation that has been rarely considered when assessing the robustness of circadian clocks.

  15. Modeling two-oscillator circadian systems entrained by two environmental cycles.

    Science.gov (United States)

    Oda, Gisele A; Friesen, W Otto

    2011-01-01

    Several experimental studies have altered the phase relationship between photic and non-photic environmental, 24 h cycles (zeitgebers) in order to assess their role in the synchronization of circadian rhythms. To assist in the interpretation of the complex activity patterns that emerge from these "conflicting zeitgeber" protocols, we present computer simulations of coupled circadian oscillators forced by two independent zeitgebers. This circadian system configuration was first employed by Pittendrigh and Bruce (1959), to model their studies of the light and temperature entrainment of the eclosion oscillator in Drosophila. Whereas most of the recent experiments have restricted conflicting zeitgeber experiments to two experimental conditions, by comparing circadian oscillator phases under two distinct phase relationships between zeitgebers (usually 0 and 12 h), Pittendrigh and Bruce compared eclosion phase under 12 distinct phase relationships, spanning the 24 h interval. Our simulations using non-linear differential equations replicated complex non-linear phenomena, such as "phase jumps" and sudden switches in zeitgeber preferences, which had previously been difficult to interpret. Our simulations reveal that these phenomena generally arise when inter-oscillator coupling is high in relation to the zeitgeber strength. Manipulations in the structural symmetry of the model indicated that these results can be expected to apply to a wide range of system configurations. Finally, our studies recommend the use of the complete protocol employed by Pittendrigh and Bruce, because different system configurations can generate similar results when a "conflicting zeitgeber experiment" incorporates only two phase relationships between zeitgebers.

  16. Circadian desynchrony promotes metabolic disruption in a mouse model of shiftwork.

    Directory of Open Access Journals (Sweden)

    Johanna L Barclay

    Full Text Available Shiftwork is associated with adverse metabolic pathophysiology, and the rising incidence of shiftwork in modern societies is thought to contribute to the worldwide increase in obesity and metabolic syndrome. The underlying mechanisms are largely unknown, but may involve direct physiological effects of nocturnal light exposure, or indirect consequences of perturbed endogenous circadian clocks. This study employs a two-week paradigm in mice to model the early molecular and physiological effects of shiftwork. Two weeks of timed sleep restriction has moderate effects on diurnal activity patterns, feeding behavior, and clock gene regulation in the circadian pacemaker of the suprachiasmatic nucleus. In contrast, microarray analyses reveal global disruption of diurnal liver transcriptome rhythms, enriched for pathways involved in glucose and lipid metabolism and correlating with first indications of altered metabolism. Although altered food timing itself is not sufficient to provoke these effects, stabilizing peripheral clocks by timed food access can restore molecular rhythms and metabolic function under sleep restriction conditions. This study suggests that peripheral circadian desynchrony marks an early event in the metabolic disruption associated with chronic shiftwork. Thus, strengthening the peripheral circadian system by minimizing food intake during night shifts may counteract the adverse physiological consequences frequently observed in human shift workers.

  17. A software solution for recording circadian oscillator features in time-lapse live cell microscopy

    Directory of Open Access Journals (Sweden)

    Salmon Patrick

    2010-07-01

    Full Text Available Abstract Background Fluorescent and bioluminescent time-lapse microscopy approaches have been successfully used to investigate molecular mechanisms underlying the mammalian circadian oscillator at the single cell level. However, most of the available software and common methods based on intensity-threshold segmentation and frame-to-frame tracking are not applicable in these experiments. This is due to cell movement and dramatic changes in the fluorescent/bioluminescent reporter protein during the circadian cycle, with the lowest expression level very close to the background intensity. At present, the standard approach to analyze data sets obtained from time lapse microscopy is either manual tracking or application of generic image-processing software/dedicated tracking software. To our knowledge, these existing software solutions for manual and automatic tracking have strong limitations in tracking individual cells if their plane shifts. Results In an attempt to improve existing methodology of time-lapse tracking of a large number of moving cells, we have developed a semi-automatic software package. It extracts the trajectory of the cells by tracking theirs displacements, makes the delineation of cell nucleus or whole cell, and finally yields measurements of various features, like reporter protein expression level or cell displacement. As an example, we present here single cell circadian pattern and motility analysis of NIH3T3 mouse fibroblasts expressing a fluorescent circadian reporter protein. Using Circadian Gene Express plugin, we performed fast and nonbiased analysis of large fluorescent time lapse microscopy datasets. Conclusions Our software solution, Circadian Gene Express (CGE, is easy to use and allows precise and semi-automatic tracking of moving cells over longer period of time. In spite of significant circadian variations in protein expression with extremely low expression levels at the valley phase, CGE allows accurate and

  18. Circadian rhythm characteristics of oral squamous cell carcinoma growth in an orthotopic xenograft model

    Directory of Open Access Journals (Sweden)

    Zhao NB

    2013-01-01

    Full Text Available Ningbo Zhao,* Hong Tang,* Kai Yang, Dan Chen Department of Oral and Maxillofacial Surgery, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China*These authors contributed equally to this workBackground: Recent studies show that circadian rhythm changes are closely related to the occurrence and development of various tumors, such as breast, liver, and prostate. However, there are significant differences in circadian rhythm between different tumors. At present, the circadian rhythm characteristics of oral cancer remain unknown. The purpose of this study is to investigate the circadian rhythm characteristics of the in vivo growth of oral squamous cell carcinoma (OSCC.Materials and methods: Thirty-two nude mice were placed under 12-hour light/12-hour dark cycles. The human OSCC cell line BcaCD885 was inoculated in the cheek of nude mice. After 3 weeks, eight mice were sacrificed at four time points, including 4 hours after light onset (HALO, 10 HALO, 16 HALO, and 22 HALO, during a period of 24 hours. The volume of excised tumors was measured and the proliferative index (PI and apoptotic index (AI of tumor cells were determined by flow cytometry. A cosine analysis method was used to determine whether the tumor volume, PI, and AI obeyed a circadian rhythm.Results: There was a significant circadian rhythm in the tumor volume and PI of OSCC cells. For the tumor volume, there were significant differences between the four time points. The peak and trough values of the tumor volume appeared at 3.23 HALO and 15.23 HALO, whereas the peak and trough values of PI appeared at 6.60 HALO and 18.16 HALO, respectively. However, there was no circadian rhythm in the AI of tumor cells, despite significant differences between the four time points.Conclusion: This study demonstrates, for the first time, that the tumor volume and PI of in vivo growing OSCC undergo circadian rhythms. These results support the assertion that time factor should be

  19. Circadian systems biology: When time matters

    Directory of Open Access Journals (Sweden)

    Luise Fuhr

    2015-01-01

    In this manuscript we review the combination of experimental methodologies, bioinformatics and theoretical models that have been essential to explore this remarkable timing-system. Such an integrative and interdisciplinary approach may provide new strategies with regard to chronotherapeutic treatment and new insights concerning the restoration of the circadian timing in clock-associated diseases.

  20. Impact of nutrients on circadian rhythmicity

    NARCIS (Netherlands)

    Oosterman, Johanneke E; Kalsbeek, A.; la Fleur, Susanne E; Belsham, Denise D

    2015-01-01

    The suprachiasmatic nucleus (SCN) in the mammalian hypothalamus functions as an endogenous pacemaker that generates and maintains circadian rhythms throughout the body. Next to this central clock, peripheral oscillators exist in almost all mammalian tissues. Whereas the SCN is mainly entrained to th

  1. Circadian Variation in Coronary Stent Thrombosis

    NARCIS (Netherlands)

    Mahmoud, Karim D.; Lennon, Ryan J.; Ting, Henry H.; Rihal, Charanjit S.; Holmes, David R.

    2011-01-01

    Objectives We sought to determine the circadian, weekly, and seasonal variation of coronary stent thrombosis. Background Other adverse cardiovascular events such as acute myocardial infarction are known to have higher incidences during the early morning hours, Mondays, and winter months. Methods The

  2. [Circadian rhythm of human lymphocyte subpopulations].

    Science.gov (United States)

    Pasqualetti, P; Colantonio, D; Casale, R; Colangeli, S; Natali, G

    1988-01-01

    Circadian rhythm of lymphocyte subsets was investigated in four healthy subjects, males, aged 35-58 years old. After a period of ambiental synchronization, venous blood samples were taken during a span of a day at 0.00 a.m., 4.00 a.m., 8.00 a.m., noon, 4.00 p.m. and 8.00 p.m. Lymphocyte subsets (OKT3, OKT4, OKT8, OKB7, OKJa1) were determined by monoclonal antibodies method, and serum level of cortisol by radioimmunoassay method. The OKT4/OKT8 ratio was also calculated. Data were analyzed by chronograms (mean +/- 1SD) and by cosinor method. Results show a significant circadian rhythm for each lymphocyte subset and for serum cortisol levels. The lowest levels of all circulating subsets were seen between noon and 4.00 p.m. and the highest levels around midnight, inversely related with the circadian rhythm of serum cortisol. The OKT4/OKT8 ratio, on the contrary, was relatively constant during the day, without a significant circadian rhythm. These observations have laboratoristic, clinical, and therapeutic implications and should be considered in the course of immunological studies.

  3. Light and the human circadian clock

    NARCIS (Netherlands)

    Roenneberg, Till; Kantermann, Thomas; Juda, Myriam; Vetter, Céline; Allebrandt, Karla V

    2013-01-01

    The circadian clock can only reliably fulfil its function if it is stably entrained. Most clocks use the light-dark cycle as environmental signal (zeitgeber) for this active synchronisation. How we think about clock function and entrainment has been strongly influenced by the early concepts of the

  4. Circadian clocks - from genes to complex behaviour

    NARCIS (Netherlands)

    Roenneberg, Till; Merrow, Martha

    1999-01-01

    Circadian clocks control temporal structure in practically all organisms and on all levels of biology, from gene expression to complex behaviour and cognition. Over the last decades, research has begun to unravel the physiological and, more recently, molecular mechanisms that underlie this endogenou

  5. Circadian dysregulation disrupts bile acid homeostasis.

    Directory of Open Access Journals (Sweden)

    Ke Ma

    Full Text Available BACKGROUND: Bile acids are potentially toxic compounds and their levels of hepatic production, uptake and export are tightly regulated by many inputs, including circadian rhythm. We tested the impact of disrupting the peripheral circadian clock on integral steps of bile acid homeostasis. METHODOLOGY/PRINCIPAL FINDINGS: Both restricted feeding, which phase shifts peripheral clocks, and genetic ablation in Per1(-/-/Per2(-/- (PERDKO mice disrupted normal bile acid control and resulted in hepatic cholestasis. Restricted feeding caused a dramatic, transient elevation in hepatic bile acid levels that was associated with activation of the xenobiotic receptors CAR and PXR and elevated serum aspartate aminotransferase (AST, indicative of liver damage. In the PERDKO mice, serum bile acid levels were elevated and the circadian expression of key bile acid synthesis and transport genes, including Cyp7A1 and NTCP, was lost. This was associated with blunted expression of a primary clock output, the transcription factor DBP, which transactivates the promoters of both genes. CONCLUSIONS/SIGNIFICANCE: We conclude that disruption of the circadian clock results in dysregulation of bile acid homeostasis that mimics cholestatic disease.

  6. Light and the human circadian clock

    NARCIS (Netherlands)

    Roenneberg, Till; Kantermann, Thomas; Juda, Myriam; Vetter, Céline; Allebrandt, Karla V

    2013-01-01

    The circadian clock can only reliably fulfil its function if it is stably entrained. Most clocks use the light-dark cycle as environmental signal (zeitgeber) for this active synchronisation. How we think about clock function and entrainment has been strongly influenced by the early concepts of the f

  7. Temperature compensation and entrainment in circadian rhythms

    Science.gov (United States)

    Bodenstein, C.; Heiland, I.; Schuster, S.

    2012-06-01

    To anticipate daily variations in the environment and coordinate biological activities into a daily cycle many organisms possess a circadian clock. In the absence of external time cues the circadian rhythm persists with a period of approximately 24 h. The clock phase can be shifted by single pulses of light, darkness, chemicals, or temperature and this allows entrainment of the clock to exactly 24 h by cycles of these zeitgebers. On the other hand, the period of the circadian rhythm is kept relatively constant within a physiological range of constant temperatures, which means that the oscillator is temperature compensated. The mechanisms behind temperature compensation and temperature entrainment are not fully understood, neither biochemically nor mathematically. Here, we theoretically investigate the interplay of temperature compensation and entrainment in general oscillatory systems. We first give an analytical treatment for small temperature shifts and derive that every temperature-compensated oscillator is entrainable to external small-amplitude temperature cycles. Temperature compensation ensures that this entrainment region is always centered at the endogenous period regardless of possible seasonal temperature differences. Moreover, for small temperature cycles the entrainment region of the oscillator is potentially larger for rectangular pulses. For large temperature shifts we numerically analyze different circadian clock models proposed in the literature with respect to these properties. We observe that for such large temperature shifts sinusoidal or gradual temperature cycles allow a larger entrainment region than rectangular cycles.

  8. Daily changes in temperature, not the circadian clock, regulate growth rate in Brachypodium distachyon.

    Directory of Open Access Journals (Sweden)

    Dominick A Matos

    Full Text Available Plant growth is commonly regulated by external cues such as light, temperature, water availability, and internal cues generated by the circadian clock. Changes in the rate of growth within the course of a day have been observed in the leaves, stems, and roots of numerous species. However, the relative impact of the circadian clock on the growth of grasses has not been thoroughly characterized. We examined the influence of diurnal temperature and light changes, and that of the circadian clock on leaf length growth patterns in Brachypodium distachyon using high-resolution time-lapse imaging. Pronounced changes in growth rate were observed under combined photocyles and thermocycles or with thermocycles alone. A considerably more rapid growth rate was observed at 28°C than 12°C, irrespective of the presence or absence of light. In spite of clear circadian clock regulated gene expression, plants exhibited no change in growth rate under conditions of constant light and temperature, and little or no effect under photocycles alone. Therefore, temperature appears to be the primary cue influencing observed oscillations in growth rate and not the circadian clock or photoreceptor activity. Furthermore, the size of the leaf meristem and final cell length did not change in response to changes in temperature. Therefore, the nearly five-fold difference in growth rate observed across thermocycles can be attributed to proportionate changes in the rate of cell division and expansion. A better understanding of the growth cues in B. distachyon will further our ability to model metabolism and biomass accumulation in grasses.

  9. Daily changes in temperature, not the circadian clock, regulate growth rate in Brachypodium distachyon.

    Science.gov (United States)

    Matos, Dominick A; Cole, Benjamin J; Whitney, Ian P; MacKinnon, Kirk J-M; Kay, Steve A; Hazen, Samuel P

    2014-01-01

    Plant growth is commonly regulated by external cues such as light, temperature, water availability, and internal cues generated by the circadian clock. Changes in the rate of growth within the course of a day have been observed in the leaves, stems, and roots of numerous species. However, the relative impact of the circadian clock on the growth of grasses has not been thoroughly characterized. We examined the influence of diurnal temperature and light changes, and that of the circadian clock on leaf length growth patterns in Brachypodium distachyon using high-resolution time-lapse imaging. Pronounced changes in growth rate were observed under combined photocyles and thermocycles or with thermocycles alone. A considerably more rapid growth rate was observed at 28°C than 12°C, irrespective of the presence or absence of light. In spite of clear circadian clock regulated gene expression, plants exhibited no change in growth rate under conditions of constant light and temperature, and little or no effect under photocycles alone. Therefore, temperature appears to be the primary cue influencing observed oscillations in growth rate and not the circadian clock or photoreceptor activity. Furthermore, the size of the leaf meristem and final cell length did not change in response to changes in temperature. Therefore, the nearly five-fold difference in growth rate observed across thermocycles can be attributed to proportionate changes in the rate of cell division and expansion. A better understanding of the growth cues in B. distachyon will further our ability to model metabolism and biomass accumulation in grasses.

  10. Circadian polymorphisms associated with affective disorders

    Directory of Open Access Journals (Sweden)

    Shekhtman Tatyana

    2009-01-01

    Full Text Available Abstract Background Clinical symptoms of affective disorders, their response to light treatment, and sensitivity to other circadian interventions indicate that the circadian system has a role in mood disorders. Possibly the mechanisms involve circadian seasonal and photoperiodic mechanisms. Since genetic susceptibilities contribute a strong component to affective disorders, we explored whether circadian gene polymorphisms were associated with affective disorders in four complementary studies. Methods Four groups of subjects were recruited from several sources: 1 bipolar proband-parent trios or sib-pair-parent nuclear families, 2 unrelated bipolar participants who had completed the BALM morningness-eveningness questionnaire, 3 sib pairs from the GenRed Project having at least one sib with early-onset recurrent unipolar depression, and 4 a sleep clinic patient group who frequently suffered from depression. Working mainly with the SNPlex assay system, from 2 to 198 polymorphisms in genes related to circadian function were genotyped in the participant groups. Associations with affective disorders were examined with TDT statistics for within-family comparisons. Quantitative trait associations were examined within the unrelated samples. Results In NR1D1, rs2314339 was associated with bipolar disorder (P = 0.0005. Among the unrelated bipolar participants, 3 SNPs in PER3 and CSNK1E were associated with the BALM score. A PPARGC1B coding SNP, rs7732671, was associated with affective disorder with nominal significance in bipolar family groups and independently in unipolar sib pairs. In TEF, rs738499 was associated with unipolar depression; in a replication study, rs738499 was also associated with the QIDS-SR depression scale in the sleep clinic patient sample. Conclusion Along with anti-manic effects of lithium and the antidepressant effects of bright light, these findings suggest that perturbations of the circadian gene network at several levels may

  11. Probing entrainment of Ostreococcus tauri circadian clock by green and blue light through a mathematical modeling approach.

    Science.gov (United States)

    Thommen, Quentin; Pfeuty, Benjamin; Schatt, Philippe; Bijoux, Amandine; Bouget, François-Yves; Lefranc, Marc

    2015-01-01

    Most organisms anticipate daily environmental variations and orchestrate cellular functions thanks to a circadian clock which entrains robustly to the day/night cycle, despite fluctuations in light intensity due to weather or seasonal variations. Marine organisms are also subjected to fluctuations in light spectral composition as their depth varies, due to differential absorption of different wavelengths by sea water. Studying how light input pathways contribute to circadian clock robustness is therefore important. Ostreococcus tauri, a unicellular picoplanktonic marine green alga with low genomic complexity and simple cellular organization, has become a promising model organism for systems biology. Functional and modeling approaches have shown that a core circadian oscillator based on orthologs of Arabidopsis TOC1 and CCA1 clock genes accounts for most experimental data acquired under a wide range of conditions. Some evidence points at putative light input pathway(s) consisting of a two-component signaling system (TCS) controlled by the only two histidine kinases (HK) of O. tauri. LOV-HK is a blue light photoreceptor under circadian control, that is required for circadian clock function. An involvement of Rhodopsin-HK (Rhod-HK) is also conceivable since rhodopsin photoreceptors mediate blue to green light input in animal circadian clocks. Here, we probe the role of LOV-HK and Rhod-HK in mediating light input to the TOC1-CCA1 oscillator using a mathematical model incorporating the TCS hypothesis. This model agrees with clock gene expression time series representative of multiple environmental conditions in blue or green light, characterizing entrainment by light/dark cycles, free-running in constant light, and resetting. Experimental and theoretical results indicate that both blue and green light can reset O. tauri circadian clock. Moreover, our mathematical analysis suggests that Rhod-HK is a blue-green light receptor and drives the clock together with LOV-HK.

  12. period-1 encodes an ATP-dependent RNA helicase that influences nutritional compensation of the Neurospora circadian clock

    Energy Technology Data Exchange (ETDEWEB)

    Emerson, Jillian M.; Bartholomai, Bradley M.; Ringelberg, Carol; Baker, Scott E.; Loros, Jennifer J.; Dunlap, Jay C.

    2015-12-22

    Mutants in the period-1 (prd-1) gene, characterized by a recessive allele, display a reduced growth rate and period lengthening of the developmental cycle controlled by the circadian clock. We refined the genetic location of prd-1 and used whole genome sequencing to find the mutation defining it, confirming the identity of prd-1 by rescuing the mutant circadian phenotype via transformation. PRD-1 is an RNA helicase whose orthologs, DDX5 and DDX17 in humans and Dbp2p in yeast, are implicated in various processes including transcriptional regulation, elongation, and termination, 23 ribosome biogenesis, and RNA decay. Although prdi-1smutantssiois an ATP-dependent RNA helicase, member of a sub-family display a long period (~25 hrs) circadian developmental cycle, they interestingly display a wild type period when the core circadian oscillator is tracked using a frq-luciferase transcriptional fusion under conditions of limiting nutritional carbon; the core oscillator runs with a long period under glucose-sufficient conditions. Thus PRD-1 clearly impacts the circadian oscillator and is not only part of a metabolic oscillator ancillary to the core clock. PRD-1 is an essential protein and its expression is neither light-regulated nor clock-regulated. However, it is transiently induced by glucose; in the presence of sufficient glucose PRD-1 is in the nucleus until glucose runs out which elicits its disappearance from the nucleus. Because circadian period length is carbon concentration-dependent, prd­-1 may be formally viewed as clock mutant with defective nutritional compensation of circadian period length.

  13. Coupling of a core post-translational pacemaker to a slave transcription/translation feedback loop in a circadian system.

    Directory of Open Access Journals (Sweden)

    Ximing Qin

    Full Text Available Cyanobacteria are the only model circadian clock system in which a circadian oscillator can be reconstituted in vitro. The underlying circadian mechanism appears to comprise two subcomponents: a post-translational oscillator (PTO and a transcriptional/translational feedback loop (TTFL. The PTO and TTFL have been hypothesized to operate as dual oscillator systems in cyanobacteria. However, we find that they have a definite hierarchical interdependency-the PTO is the core pacemaker while the TTFL is a slave oscillator that quickly damps when the PTO stops. By analysis of overexpression experiments and mutant clock proteins, we find that the circadian system is dependent upon the PTO and that suppression of the PTO leads to damped TTFL-based oscillations whose temperature compensation is not stable under different metabolic conditions. Mathematical modeling indicates that the experimental data are compatible with a core PTO driving the TTFL; the combined PTO/TTFL system is resilient to noise. Moreover, the modeling indicates a mechanism by which the TTFL can feed into the PTO such that new synthesis of clock proteins can phase-shift or entrain the core PTO pacemaker. This prediction was experimentally tested and confirmed by entraining the in vivo circadian system with cycles of new clock protein synthesis that modulate the phosphorylation status of the clock proteins in the PTO. In cyanobacteria, the PTO is the self-sustained core pacemaker that can operate independently of the TTFL, but the TTFL damps when the phosphorylation status of the PTO is clamped. However, the TTFL can provide entraining input into the PTO. This study is the first to our knowledge to experimentally and theoretically investigate the dynamics of a circadian clock in which a PTO is coupled to a TTFL. These results have important implications for eukaryotic clock systems in that they can explain how a TTFL could appear to be a core circadian clockwork when in fact the true

  14. Structural characterization of the circadian clock protein complex composed of KaiB and KaiC by inverse contrast-matching small-angle neutron scattering

    Science.gov (United States)

    Sugiyama, Masaaki; Yagi, Hirokazu; Ishii, Kentaro; Porcar, Lionel; Martel, Anne; Oyama, Katsuaki; Noda, Masanori; Yunoki, Yasuhiro; Murakami, Reiko; Inoue, Rintaro; Sato, Nobuhiro; Oba, Yojiro; Terauchi, Kazuki; Uchiyama, Susumu; Kato, Koichi

    2016-01-01

    The molecular machinery of the cyanobacterial circadian clock consists of three proteins: KaiA, KaiB, and KaiC. Through interactions among the three Kai proteins, the phosphorylation states of KaiC generate circadian oscillations in vitro in the presence of ATP. Here, we characterized the complex formation between KaiB and KaiC using a phospho-mimicking mutant of KaiC, which had an aspartate substitution at the Ser431 phosphorylation site and exhibited optimal binding to KaiB. Mass-spectrometric titration data showed that the proteins formed a complex exclusively in a 6:6 stoichiometry, indicating that KaiB bound to the KaiC hexamer with strong positive cooperativity. The inverse contrast-matching technique of small-angle neutron scattering enabled selective observation of KaiB in complex with the KaiC mutant with partial deuteration. It revealed a disk-shaped arrangement of the KaiB subunits on the outer surface of the KaiC C1 ring, which also serves as the interaction site for SasA, a histidine kinase that operates as a clock-output protein in the regulation of circadian transcription. These data suggest that cooperatively binding KaiB competes with SasA with respect to interaction with KaiC, thereby promoting the synergistic release of this clock-output protein from the circadian oscillator complex. PMID:27752127

  15. Ribosome evolution: Emergence of peptide synthesis machinery

    Indian Academy of Sciences (India)

    Koji Tamura

    2011-12-01

    Proteins, the main players in current biological systems, are produced on ribosomes by sequential amide bond (peptide bond) formations between amino-acid-bearing tRNAs. The ribosome is an exquisite super-complex of RNA-proteins, containing more than 50 proteins and at least 3 kinds of RNAs. The combination of a variety of side chains of amino acids (typically 20 kinds with some exceptions) confers proteins with extraordinary structure and functions. The origin of peptide bond formation and the ribosome is crucial to the understanding of life itself. In this article, a possible evolutionary pathway to peptide bond formation machinery (proto-ribosome) will be discussed, with a special focus on the RNA minihelix (primordial form of modern tRNA) as a starting molecule. Combining the present data with recent experimental data, we can infer that the peptidyl transferase center (PTC) evolved from a primitive system in the RNA world comprising tRNA-like molecules formed by duplication of minihelix-like small RNA.

  16. Occupational Accidents with Agricultural Machinery in Austria.

    Science.gov (United States)

    Kogler, Robert; Quendler, Elisabeth; Boxberger, Josef

    2016-01-01

    The number of recognized accidents with fatalities during agricultural and forestry work, despite better technology and coordinated prevention and trainings, is still very high in Austria. The accident scenarios in which people are injured are very different on farms. The common causes of accidents in agriculture and forestry are the loss of control of machine, means of transport or handling equipment, hand-held tool, and object or animal, followed by slipping, stumbling and falling, breakage, bursting, splitting, slipping, fall, and collapse of material agent. In the literature, a number of studies of general (machine- and animal-related accidents) and specific (machine-related accidents) agricultural and forestry accident situations can be found that refer to different databases. From the database Data of the Austrian Workers Compensation Board (AUVA) about occupational accidents with different agricultural machinery over the period 2008-2010 in Austria, main characteristics of the accident, the victim, and the employer as well as variables on causes and circumstances by frequency and contexts of parameters were statistically analyzed by employing the chi-square test and odds ratio. The aim of the study was to determine the information content and quality of the European Statistics on Accidents at Work (ESAW) variables to evaluate safety gaps and risks as well as the accidental man-machine interaction.

  17. Circadian adaptations to meal timing: Neuroendocrine mechanisms

    Directory of Open Access Journals (Sweden)

    Danica F Patton

    2013-10-01

    Full Text Available Circadian rhythms of behavior and physiology are generated by central and peripheral circadian oscillators entrained by periodic environmental or physiological stimuli. A master circadian pacemaker in the hypothalamic suprachiasmatic nucleus is directly entrained by daily light-dark cycles, and coordinates the timing of other oscillators by direct and indirect neural, hormonal and behavioral outputs. The daily rhythm of food intake provides stimuli that entrain most peripheral and central oscillators, some of which can drive a daily rhythm of food anticipatory activity if food is restricted to one daily mealtime. The location of food-entrainable oscillators (FEOs that drive food anticipatory rhythms, and the food-related stimuli that entrain these oscillators, remain to be clarified. Here, we critically examine the role of peripheral metabolic hormones as potential internal entrainment stimuli or outputs for FEOs controlling food anticipatory rhythms in rats and mice. Hormones for which data are available include corticosterone, ghrelin, leptin, insulin, glucagon, and glucagon-like peptide 1. All of these hormones exhibit daily rhythms of synthesis and secretion that are synchronized by meal timing. There is some evidence that ghrelin and leptin modulate the expression of food anticipatory rhythms, but none of the hormones examined so far are necessary for entrainment. Ghrelin and leptin likely modulate food-entrained rhythms by actions in hypothalamic circuits utilizing melanocortin and orexin signaling, although again food-entrained behavioral rhythms can persist in lesion and gene knockout models in which these systems are disabled. Actions of these hormones on circadian oscillators in central reward circuits remain to be evaluated. Food-entrained activity rhythms are likely mediated by a distributed system of circadian oscillators sensitive to multiple feeding related inputs. Metabolic hormones appear to play a modulatory role within this

  18. Protecting the Melatonin Rhythm through Circadian Healthy Light Exposure

    Directory of Open Access Journals (Sweden)

    Maria Angeles Bonmati-Carrion

    2014-12-01

    Full Text Available Currently, in developed countries, nights are excessively illuminated (light at night, whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD, including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system.

  19. Protecting the Melatonin Rhythm through Circadian Healthy Light Exposure

    Science.gov (United States)

    Bonmati-Carrion, Maria Angeles; Arguelles-Prieto, Raquel; Martinez-Madrid, Maria Jose; Reiter, Russel; Hardeland, Ruediger; Rol, Maria Angeles; Madrid, Juan Antonio

    2014-01-01

    Currently, in developed countries, nights are excessively illuminated (light at night), whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD), including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs) and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system. PMID:25526564

  20. Time to flower: interplay between photoperiod and the circadian clock.

    Science.gov (United States)

    Johansson, Mikael; Staiger, Dorothee

    2015-02-01

    Plants precisely time the onset of flowering to ensure reproductive success. A major factor in seasonal control of flowering time is the photoperiod. The length of the daily light period is measured by the circadian clock in leaves, and a signal is conveyed to the shoot apex to initiate floral transition accordingly. In the last two decades, the molecular players in the photoperiodic pathway have been identified in Arabidopsis thaliana. Moreover, the intricate connections between the circadian clockwork and components of the photoperiodic pathway have been unravelled. In particular, the molecular basis of time-of-day-dependent sensitivity to floral stimuli, as predicted by Bünning and Pittendrigh, has been elucidated. This review covers recent insights into the molecular mechanisms underlying clock regulation of photoperiodic responses and the integration of the photoperiodic pathway into the flowering time network in Arabidopsis. Furthermore, examples of conservation and divergence in photoperiodic flower induction in other plant species are discussed. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  1. Diet-Induced Obesity and Circadian Disruption of Feeding Behavior

    Science.gov (United States)

    Blancas-Velazquez, Aurea; Mendoza, Jorge; Garcia, Alexandra N.; la Fleur, Susanne E.

    2017-01-01

    Feeding behavior shows a rhythmic daily pattern, which in nocturnal rodents is observed mainly during the dark period. This rhythmicity is under the influence of the hypothalamic suprachiasmatic nucleus (SCN), the main biological clock. Nevertheless, various studies have shown that in rodent models of obesity, using high-energy diets, the general locomotor activity and feeding rhythms can be disrupted. Here, we review the data on the effects of diet-induced obesity (DIO) on locomotor activity and feeding patterns, as well as the effect on the brain sites within the neural circuitry involved in metabolic and rewarding feeding behavior. In general, DIO may alter locomotor activity by decreasing total activity. On the other hand, DIO largely alters eating patterns, producing increased overall ingestion and number of eating bouts that can extend to the resting period. Furthermore, within the hypothalamic areas, little effect has been reported on the molecular circadian mechanism in DIO animals with ad libitum hypercaloric diets and little or no data exist so far on its effects on the reward system areas. We further discuss the possibility of an uncoupling of metabolic and reward systems in DIO and highlight a gap of circadian and metabolic research that may help to better understand the implications of obesity. PMID:28223912

  2. Circadian entrainment and its role in depression: a mechanistic review.

    Science.gov (United States)

    Lall, G S; Atkinson, L A; Corlett, S A; Broadbridge, P J; Bonsall, D R

    2012-10-01

    The natural rotation of the earth generates an environmental day-night cycle that repeats every 24 h. This daily transition from dawn to dusk provides one of the most important time cues to which the majority of organisms synchronise their activity. Under these conditions, natural light, a photic stimulus, provides the principal entraining cue. In mammals, an endogenous circadian pacemaker located within the suprachiasmatic nucleus (SCN) of the hypothalamus acts as a coordinating centre to align physiological activity with the environmental light-dark cycle. However, the SCN also receives regulatory input from a number of behavioural, non-photic, cues such as physical activity, social interactions and feeding routines. The unique ability of the SCN to integrate both photic and non-photic cues allows it to generate a rhythm that is tailored to the individual and entrained to the environment. Here, we review the key neurotransmitter systems involved in both photic and non-photic transmission to the SCN and their interactions that assist in generating an entrained output rhythm. We also consider the impact on health of a desynchronised circadian system with a focus on depressive affective disorders and current therapies aimed at manipulating the relationship between photic and non-photic SCN regulators.

  3. Integration of light signaling with photoperiodic flowering and circadian rhythm

    Institute of Scientific and Technical Information of China (English)

    Min NI

    2005-01-01

    Plants become photosynthetic through de-etiolation, a developmental process regulated by red/far-red light-absorbing phytochromes and blue/ultraviolet A light-absorbing cryptochromes. Genetic screens have identified in the last decade many far-red light signaling mutants and several red and blue light signaling mutants, suggesting the existence of distinct red, far-red, or blue light signaling pathways downstream of phytochromes and cryptochromes. However, genetic screens have also identified mutants with defective de-etiolation responses under multiple wavelengths. Thus, the optimal de-etiolation responses of a plant depend on coordination among the different light signaling pathways. This review intends to discuss several recently identified signaling components that have a potential role to integrate red, far-red, and blue light signalings. This review also highlights the recent discoveries on proteolytic degradation in the desensitization of light signal transmission, and the tight connection of light signaling with photoperiodic flowering and circadian rhythm. Studies on the controlling mechanisms of de-etiolation, photoperiodic flowering, and circadian rhythm have been the fascinating topics in Arabidopsis research. The knowledge obtained from Arabidopsis can be readily applied to food crops and ornamental species, and can be contributed to our general understanding of signal perception and transduction in all organisms.

  4. Condition Monitoring of Machinery in Non-Stationary Operations : Proceedings of the Second International Conference "Condition Monitoring of Machinery in Non-Stationnary Operations"

    CERN Document Server

    Bartelmus, Walter; Chaari, Fakher; Zimroz, Radoslaw; Haddar, Mohamed

    2012-01-01

    Condition monitoring of machines in non-stationary operations (CMMNO) can be seen as the major challenge for research in the field of machinery diagnostics. Condition monitoring of machines in non-stationary operations is the title of the presented book and the title of the Conference held in Hammamet - Tunisia March 26 – 28, 2012. It is the second conference under this title, first took place in Wroclaw - Poland , March 2011. The subject CMMNO comes directly from industry needs and observation of real objects. Most monitored and diagnosed objects used in industry works in non-stationary operations condition. The non-stationary operations come from fulfillment of machinery tasks, for which they are designed for. All machinery used in different kind of mines, transport systems, vehicles like: cars, buses etc, helicopters, ships and battleships and so on work in non-stationary operations. The papers included in the book are shaped by the organizing board of the conference and authors of the papers. The papers...

  5. Putative pacemakers in the eyestalk and brain of the crayfish Procambarus clarkii show circadian oscillations in levels of mRNA for crustacean hyperglycemic hormone.

    Directory of Open Access Journals (Sweden)

    Janikua Nelson-Mora

    Full Text Available Crustacean hyperglycemic hormone (CHH synthesizing cells in the optic lobe, one of the pacemakers of the circadian system, have been shown to be present in crayfish. However, the presence of CHH in the central brain, another putative pacemaker of the multi-oscillatory circadian system, of this decapod and its circadian transcription in the optic lobe and brain have yet to be explored. Therefore, using qualitative and quantitative PCR, we isolated and cloned a CHH mRNA fragment from two putative pacemakers of the multi-oscillatory circadian system of Procambarus clarkii, the optic lobe and the central brain. This CHH transcript synchronized to daily light-dark cycles and oscillated under dark, constant conditions demonstrating statistically significant daily and circadian rhythms in both structures. Furthermore, to investigate the presence of the peptide in the central brain of this decapod, we used immunohistochemical methods. Confocal microscopy revealed the presence of CHH-IR in fibers and cells of the protocerebral and tritocerebal clusters and neuropiles, particularly in some neurons located in clusters 6, 14, 15 and 17. The presence of CHH positive neurons in structures of P. clarkii where clock proteins have been reported suggests a relationship between the circadian clockwork and CHH. This work provides new insights into the circadian regulation of CHH, a pleiotropic hormone that regulates many physiological processes such as glucose metabolism and osmoregulatory responses to stress.

  6. Vibration Signal Forecasting on Rotating Machinery by means of Signal Decomposition and Neurofuzzy Modeling

    Directory of Open Access Journals (Sweden)

    Daniel Zurita-Millán

    2016-01-01

    Full Text Available Vibration monitoring plays a key role in the industrial machinery reliability since it allows enhancing the performance of the machinery under supervision through the detection of failure modes. Thus, vibration monitoring schemes that give information regarding future condition, that is, prognosis approaches, are of growing interest for the scientific and industrial communities. This work proposes a vibration signal prognosis methodology, applied to a rotating electromechanical system and its associated kinematic chain. The method combines the adaptability of neurofuzzy modeling with a signal decomposition strategy to model the patterns of the vibrations signal under different fault scenarios. The model tuning is performed by means of Genetic Algorithms along with a correlation based interval selection procedure. The performance and effectiveness of the proposed method are validated experimentally with an electromechanical test bench containing a kinematic chain. The results of the study indicate the suitability of the method for vibration forecasting in complex electromechanical systems and their associated kinematic chains.

  7. Carcinogenic effects of circadian disruption: an epigenetic viewpoint.

    Science.gov (United States)

    Salavaty, Abbas

    2015-08-08

    Circadian rhythms refer to the endogenous rhythms that are generated to synchronize physiology and behavior with 24-h environmental cues. These rhythms are regulated by both external cues and molecular clock mechanisms in almost all cells. Disruption of circadian rhythms, which is called circadian disruption, affects many biological processes within the body and results in different long-term diseases, including cancer. Circadian regulatory pathways result in rhythmic epigenetic modifications and the formation of circadian epigenomes. Aberrant epigenetic modifications, such as hypermethylation, due to circadian disruption may be involved in the transformation of normal cells into cancer cells. Several studies have indicated an epigenetic basis for the carcinogenic effects of circadian disruption. In this review, I first discuss some of the circadian genes and regulatory proteins. Then, I summarize the current evidence related to the epigenetic modifications that result in circadian disruption. In addition, I explain the carcinogenic effects of circadian disruption and highlight its potential role in different human cancers using an epigenetic viewpoint. Finally, the importance of chronotherapy in cancer treatment is highlighted.

  8. China's Textile Machinery Industry:Where to Go?

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    China's textile machinery especially cotton-spinning machinery, after several decades of development, has been relatively mature and closer to the foreign advanced level day by day; however, there are still many problems. Since China's entry into WTO, domestic textile enterprises have seized this excellent opportunity to obtain fast development and progress. Currently, accelerating the pace of technological innovation for the development of series of products, vigorously implementing the export strategy to seek new ways for technical upgrade, and exploring the new R&D mode for China's textile machinery are hanging over the enterprises' heads.

  9. Safe design and construction of machinery regulation, practice and performance

    CERN Document Server

    Bluff, Elizabeth

    2015-01-01

    The origin of this book is the compelling evidence that a high proportion of machinery-related deaths and injuries are attributable to genuine and serious risks originating within machine design and construction. This trend continues despite significant legal obligations, notably the European regulatory regime giving effect to the Machinery Directive (among others), and a substantial body of specialist knowledge originating in the disciplines of human factors and safety engineering. Grounded in empirical research with machinery manufacturers, this book aims to elucidate the factors and process

  10. Development and improvement: Status of Textile Machinery Manufacturing in China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The past over 20 years of reform & open-door practices has witnessed an amazingly rapid development in China’s textile machinery manufacturing.1. The change in the production scale: the number oftextile machinery manufacturers grew from over 150 plants listed exceptionally in the category of textile industrial system in the old traditional planned economy to the over 500 plants that come from all sectors of industries engaged in textile machinery manufacturing in the new socialist market-driven economy. The production output value grew from 870 million RMB(Chinese Yuan) in 1987 to 14.7 billion RMB, 18

  11. The ESCRT machinery: new roles at new holes.

    Science.gov (United States)

    Olmos, Y; Carlton, J G

    2016-02-01

    The ESCRT machinery drives a diverse collection of membrane remodeling events, including multivesicular body biogenesis, release of enveloped retroviruses and both reformation of the nuclear envelope and cytokinetic abscission during mitotic exit. These events share the requirement for a topologically equivalent membrane remodeling for their completion and the cells deployment of the ESCRT machinery in these different contexts highlights its functionality as a transposable membrane-fission machinery. Here, we will examine recent data describing ESCRT-III dependent membrane remodeling and explore new roles for the ESCRT-III complex at the nuclear envelope.

  12. Complementary approaches to understanding the plant circadian clock

    CERN Document Server

    Akman, Ozgur E; Loewe, Laurence; Troein, Carl; 10.4204/EPTCS.19.1

    2010-01-01

    Circadian clocks are oscillatory genetic networks that help organisms adapt to the 24-hour day/night cycle. The clock of the green alga Ostreococcus tauri is the simplest plant clock discovered so far. Its many advantages as an experimental system facilitate the testing of computational predictions. We present a model of the Ostreococcus clock in the stochastic process algebra Bio-PEPA and exploit its mapping to different analysis techniques, such as ordinary differential equations, stochastic simulation algorithms and model-checking. The small number of molecules reported for this system tests the limits of the continuous approximation underlying differential equations. We investigate the difference between continuous-deterministic and discrete-stochastic approaches. Stochastic simulation and model-checking allow us to formulate new hypotheses on the system behaviour, such as the presence of self-sustained oscillations in single cells under constant light conditions. We investigate how to model the timing of...

  13. Natural Populations of Drosophila melanogaster Reveal Features of an Uncharacterized Circadian Property: The Lower Temperature Limit of Rhythmicity.

    Science.gov (United States)

    Maguire, Sarah E; Schmidt, Paul S; Sehgal, Amita

    2014-06-01

    Most cyclic biological processes are under control of a circadian molecular timing system that synchronizes these phenomena to the 24-h day. One generic property of circadian-controlled processes is that they operate within a specific temperature range, below which the manifestation of rhythm ceases. Little is known about the evolutionary relevance of the lower temperature limit of rhythmicity or about the mechanism underlying the loss of overt circadian behavior below this lower limit, especially in one model organism of chronobiology, Drosophila melanogaster. Natural populations of Drosophila are evolving under divergent selection pressures and so provide a source of diversity necessary to address these issues. Using lines derived from African populations, we find that there is natural variation in the expression of rhythmic behavior under low-temperature conditions. We found evidence that this variability is evolutionarily relevant at extremely low temperature (12 °C) because high-altitude populations exhibit selection for locally adapted genomes that contribute to rhythmic behavior. Lines resistant to 15 °C show an additional layer of diversity in their response to temperature extremes because some lines are resistant to low temperature (15 °C) only, whereas others are cross-resistant to high and low temperature (15 °C and 30 °C). Genetic analysis of one cold-resistant circadian line at 15 °C reveals that the phenotype maps to the X-chromosome but not to the core clock genes, per and sgg. Analysis of the central clock cells of this line reveals that maintenance of rhythm is associated with robust clock function, which is compromised in a standard laboratory strain. These data indicate that the cold-resistant circadian phenotype is clock based. This study highlights the importance of using natural populations to inform us of the basic features of circadian traits, especially those that might be under temperature-based selection.

  14. Pink1 regulates mitochondrial dynamics through interaction with the fission/fusion machinery

    OpenAIRE

    Yang, Yufeng; Ouyang, Yingshi; Yang, Lichuan; Beal, M. Flint; McQuibban, Angus; Vogel, Hannes; Lu, Bingwei

    2008-01-01

    Mitochondria form dynamic tubular networks that undergo frequent morphological changes through fission and fusion, the imbalance of which can affect cell survival in general and impact synaptic transmission and plasticity in neurons in particular. Some core components of the mitochondrial fission/fusion machinery, including the dynamin-like GTPases Drp1, Mitofusin, Opa1, and the Drp1-interacting protein Fis1, have been identified. How the fission and fusion processes are regulated under norma...

  15. Soil penetration resistance in a rhodic eutrudox affected by machinery traffic and soil water content.

    OpenAIRE

    Moraes,Moacir T. de; Debiasi,Henrique; Julio C. Franchini; Silva,Vanderlei R. da

    2013-01-01

    Soil compaction caused by machinery traffic reduces crop yields. This study aimed to evaluate the effects of intensive traffic, and the soil water content, on the soil penetration resistance (PR) of a Rhodic Eutrudox (Distroferric Red Latosol, Brazilian Classification), managed under no-tillage (NT). The experiment consisted of six treatments: NT with recent chiseling, NT without additional compaction, and NT with additional compaction by 4, 8, 10 and 20 passes of a harvester with a weight of...

  16. Metabolic Profiling of Intact Arabidopsis thaliana Leaves during Circadian Cycle Using 1H High Resolution Magic Angle Spinning NMR

    Science.gov (United States)

    van Schadewijk, R.; de Groot, H. J. M.; Alia, A.

    2016-01-01

    Arabidopsis thaliana is the most widely used model organism for research in plant biology. While significant advances in understanding plant growth and development have been made by focusing on the molecular genetics of Arabidopsis, extracting and understanding the functional framework of metabolism is challenging, both from a technical perspective due to losses and modification during extraction of metabolites from the leaves, and from the biological perspective, due to random variation obscuring how well the function is performed. The purpose of this work is to establish the in vivo metabolic profile directly from the Arabidopsis thaliana leaves without metabolite extraction, to reduce the complexity of the results by multivariate analysis, and to unravel the mitigation of cellular complexity by predominant functional periodicity. To achieve this, we use the circadian cycle that strongly influences metabolic and physiological processes and exerts control over the photosynthetic machinery. High resolution-magic angle spinning nuclear magnetic resonance (HR-MAS NMR) was applied to obtain the metabolic profile directly from intact Arabidopsis leaves. Combining one- and two-dimensional 1H HR-MAS NMR allowed the identification of several metabolites including sugars and amino acids in intact leaves. Multivariate analysis on HR-MAS NMR spectra of leaves throughout the circadian cycle revealed modules of primary metabolites with significant and consistent variations of their molecular components at different time points of the circadian cycle. Since robust photosynthetic performance in plants relies on the functional periodicity of the circadian rhythm, our results show that HR-MAS NMR promises to be an important non-invasive method that can be used for metabolomics of the Arabidopsis thaliana mutants with altered physiology and photosynthetic efficiency. PMID:27662620

  17. Circadian clock genes Per1 and Per2 regulate the response of metabolism-associated transcripts to sleep disruption.

    Directory of Open Access Journals (Sweden)

    Jana Husse

    Full Text Available Human and animal studies demonstrate that short sleep or poor sleep quality, e.g. in night shift workers, promote the development of obesity and diabetes. Effects of sleep disruption on glucose homeostasis and liver physiology are well documented. However, changes in adipokine levels after sleep disruption suggest that adipocytes might be another important peripheral target of sleep. Circadian clocks regulate metabolic homeostasis and clock disruption can result in obesity and the metabolic syndrome. The finding that sleep and clock disruption have very similar metabolic effects prompted us to ask whether the circadian clock machinery may mediate the metabolic consequences of sleep disruption. To test this we analyzed energy homeostasis and adipocyte transcriptome regulation in a mouse model of shift work, in which we prevented mice from sleeping during the first six hours of their normal inactive phase for five consecutive days (timed sleep restriction--TSR. We compared the effects of TSR between wild-type and Per1/2 double mutant mice with the prediction that the absence of a circadian clock in Per1/2 mutants would result in a blunted metabolic response to TSR. In wild-types, TSR induces significant transcriptional reprogramming of white adipose tissue, suggestive of increased lipogenesis, together with increased secretion of the adipokine leptin and increased food intake, hallmarks of obesity and associated leptin resistance. Some of these changes persist for at least one week after the end of TSR, indicating that even short episodes of sleep disruption can induce prolonged physiological impairments. In contrast, Per1/2 deficient mice show blunted effects of TSR on food intake, leptin levels and adipose transcription. We conclude that the absence of a functional clock in Per1/2 double mutants protects these mice from TSR-induced metabolic reprogramming, suggesting a role of the circadian timing system in regulating the physiological effects

  18. Metabolic Profiling of Intact Arabidopsis thaliana Leaves during Circadian Cycle Using 1H High Resolution Magic Angle Spinning NMR.

    Science.gov (United States)

    Augustijn, D; Roy, U; van Schadewijk, R; de Groot, H J M; Alia, A

    Arabidopsis thaliana is the most widely used model organism for research in plant biology. While significant advances in understanding plant growth and development have been made by focusing on the molecular genetics of Arabidopsis, extracting and understanding the functional framework of metabolism is challenging, both from a technical perspective due to losses and modification during extraction of metabolites from the leaves, and from the biological perspective, due to random variation obscuring how well the function is performed. The purpose of this work is to establish the in vivo metabolic profile directly from the Arabidopsis thaliana leaves without metabolite extraction, to reduce the complexity of the results by multivariate analysis, and to unravel the mitigation of cellular complexity by predominant functional periodicity. To achieve this, we use the circadian cycle that strongly influences metabolic and physiological processes and exerts control over the photosynthetic machinery. High resolution-magic angle spinning nuclear magnetic resonance (HR-MAS NMR) was applied to obtain the metabolic profile directly from intact Arabidopsis leaves. Combining one- and two-dimensional 1H HR-MAS NMR allowed the identification of several metabolites including sugars and amino acids in intact leaves. Multivariate analysis on HR-MAS NMR spectra of leaves throughout the circadian cycle revealed modules of primary metabolites with significant and consistent variations of their molecular components at different time points of the circadian cycle. Since robust photosynthetic performance in plants relies on the functional periodicity of the circadian rhythm, our results show that HR-MAS NMR promises to be an important non-invasive method that can be used for metabolomics of the Arabidopsis thaliana mutants with altered physiology and photosynthetic efficiency.

  19. Circadian and Light Regulated Expression of CBFs and their Upstream Signalling Genes in Barley

    Science.gov (United States)

    Novák, Aliz; Ahres, Mohamed; Gulyás, Zsolt; Monostori, István; Galiba, Gábor; Vágújfalvi, Attila

    2017-01-01

    CBF (C-repeat binding factor) transcription factors show high expression levels in response to cold; moreover, they play a key regulatory role in cold acclimation processes. Recently, however, more and more information has led to the conclusion that, apart from cold, light—including its spectra—also has a crucial role in regulating CBF expression. Earlier, studies established that the expression patterns of some of these regulatory genes follow circadian rhythms. To understand more of this complex acclimation process, we studied the expression patterns of the signal transducing pathways, including signal perception, the circadian clock and phospholipid signalling pathways, upstream of the CBF gene regulatory hub. To exclude the confounding effect of cold, experiments were carried out at 22 °C. Our results show that the expression of genes implicated in the phospholipid signalling pathway follow a circadian rhythm. We demonstrated that, from among the tested CBF genes expressed in Hordeum vulgare (Hv) under our conditions, only the members of the HvCBF4-phylogenetic subgroup showed a circadian pattern. We found that the HvCBF4-subgroup genes were expressed late in the afternoon or early in the night. We also determined the expression changes under supplemental far-red illumination and established that the transcript accumulation had appeared four hours earlier and more intensely in several cases. Based on our results, we propose a model to illustrate the effect of the circadian clock and the quality of the light on the elements of signalling pathways upstream of the HvCBFs, thus integrating the complex regulation of the early cellular responses, which finally lead to an elevated abiotic stress tolerance. PMID:28829375

  20. Dissociation of circadian and light inhibition of melatonin release through forced desynchronization in the rat.

    Science.gov (United States)

    Schwartz, Michael D; Wotus, Cheryl; Liu, Tiecheng; Friesen, W Otto; Borjigin, Jimo; Oda, Gisele A; de la Iglesia, Horacio O

    2009-10-13

    Pineal melatonin release exhibits a circadian rhythm with a tight nocturnal pattern. Melatonin synthesis is regulated by the master circadian clock within the hypothalamic suprachiasmatic nucleus (SCN) and is also directly inhibited by light. The SCN is necessary for both circadian regulation and light inhibition of melatonin synthesis and thus it has been difficult to isolate these two regulatory limbs to define the output pathways by which the SCN conveys circadian and light phase information to the pineal. A 22-h light-dark (LD) cycle forced desynchrony protocol leads to the stable dissociation of rhythmic clock gene expression within the ventrolateral SCN (vlSCN) and the dorsomedial SCN (dmSCN). In the present study, we have used this protocol to assess the pattern of melatonin release under forced desynchronization of these SCN subregions. In light of our reported patterns of clock gene expression in the forced desynchronized rat, we propose that the vlSCN oscillator entrains to the 22-h LD cycle whereas the dmSCN shows relative coordination to the light-entrained vlSCN, and that this dual-oscillator configuration accounts for the pattern of melatonin release. We present a simple mathematical model in which the relative coordination of a single oscillator within the dmSCN to a single light-entrained oscillator within the vlSCN faithfully portrays the circadian phase, duration and amplitude of melatonin release under forced desynchronization. Our results underscore the importance of the SCN's subregional organization to both photic input processing and rhythmic output control.