scholarly journals In a plant's own sweet time: Sugar and circadian rhythms

2014 ◽  
Vol 36 (2) ◽  
pp. 8-11
Author(s):  
Antony N. Dodd ◽  
Alex A.R. Webb
Keyword(s):  
Circadian Rhythms ◽  
Agronomic Traits ◽  
Time Of Day ◽  
Biological Adaptation ◽  
Model Plant Arabidopsis Thaliana ◽  
Rotation Of The Earth ◽  
Molecular Bases ◽  
Crucial Part ◽  
Daily Changes ◽  
Increase Plant Productivity

Rotation of the Earth on its axis causes 24-h cycles in many features of the environment. Circadian rhythms generate a cellular measure of the time of day, providing a biological adaptation to daily changes in the environment. Plants need light to power photosynthesis in order to grow and reproduce, yet sunlight is only available for part of the 24-h day. It may therefore come as no surprise that circadian rhythms are extraordinarily important for plants. Experiments with the model plant Arabidopsis thaliana demonstrated that circadian rhythms increase plant productivity and photosynthesis1. Extension to other plant species is revealing how circadian rhythms are crucial for, and can be used to manipulate, agronomic traits of crops. Understanding and controlling the molecular bases for circadian regulation is therefore a crucial part of developing more productive crops for the next century.

296 Sex differences in sleep and wakefulness of police officers working shifts: evidence from a field study

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A118-A118
Author(s):  
Gabriela Caetano ◽  
Laura Kervezee ◽  
Fernando Gonzales-Aste ◽  
Philippe Boudreau ◽  
Diane Boivin
Keyword(s):  
Sex Differences ◽  
Circadian Rhythms ◽  
Shift Work ◽  
Police Officers ◽  
Field Studies ◽  
Time Of Day ◽  
Cycle Phase ◽  
Shift Workers ◽  
Work Related ◽  
Time Awake

Abstract Introduction National reports of work-related injuries found the excess risk of work injury attributed to shift work to be significantly higher among women. The Working Time Society (WTS) concluded that male sex is one of the few factors that is “consistently associated with perceived or actual shift work tolerance”. However, it is unclear if physiological parameters are involved. Laboratory-controlled studies report sex differences in circadian rhythms (body temperature, melatonin). In sleep deprivation protocols, alertness and cognitive performances were affected by sex, menstrual cycle phase and hormonal contraceptives [HC] use. Nevertheless, field studies that compare male and female shift workers are scarce. Methods An observational study including 76 police officers working on patrol: 56 males and 20 females (11 using [HC], 6 not using [non-HC] and 3 with unknown use of hormonal contraception) aged 32.0 ± 5.3 years. Participants were followed throughout a month-long work cycle (1,457 morning, evening, night, or other shifts, plus rest days). They filled out time-stamped questionnaires (Samn-Perelli, KSS, Visual Analogue Scales, ~5/day; sleep and work-related information, ~1–2/day), completed 5-min Psychomotor Vigilance Tasks (PVT, ~2/day), and wore an actigraph to collect activity data. Linear mixed-effects models were used to analyze the effects of group, time awake and time-of-day on fatigue, sleepiness, alertness, mood and PVT measures. Results Self-reported measures and psychomotor performance significantly varied with time awake and time-of-day. Fatigue and sleepiness levels were significantly higher among female compared to male police officers, both with time awake and across the 24-h day. These variations were similar between non-HC females and the other groups. Compared to males, HC females were more fatigued and less alert, both with time awake and across the 24-h day, and sleepier with time awake. Having children at home did not explain these differences. Conclusion The results of this study expand our knowledge on the sex differences in the sleep and circadian physiology and demonstrate a critical effect of HC on women fatigue, sleepiness and alertness when working shifts. Sex and hormonal parameters must be considered in occupational medicine as well as in future laboratory and field studies on shift workers and circadian rhythms. Support (if any) IRSST, FRQS.

Does Chronotype explain Daily Timing of Music Behaviors?

2021 ◽  
Author(s):  
Shannon Wright ◽  
Caroline Palmer
Keyword(s):  
Social Interaction ◽  
Daily Activity ◽  
Music Performance ◽  
Sleep Onset ◽  
Time Of Day ◽  
Sleep Diary ◽  
Sleep Habits ◽  
Sleep Timing ◽  
Music Making ◽  
Daily Changes

We addressed how circadian rhythms influence daily musical activities of performing musicians, who exhibit fine temporal control. Music performances often occur in the evening and late at night; evidence suggests that composing musicians tend to be later chronotypes than non-composing musicians. However, chronotype and daily music-making in performing musicians have yet to be investigated. The current study examined chronotype in actively practicing and/or performing musicians and non-musicians, and whether it was related to the daily timing of music performance. To test influences of daily changes due to the global COVID-19 pandemic, disruptions to musical, athletic, social, and sleep habits were also measured. Performing musicians, active (practicing but non-performing) musicians, inactive musicians, and non-musicians, residing in Canada, completed a 7-day online daily activity and sleep diary in Summer 2020. There were more evening chronotypes than morning chronotypes in the sample. Active/performing musicians tended to be earlier chronotypes than all other groups. Musicians' chronotype, but not nightly sleep timing, predicted the time of day that musicians made music: Late chronotypes made music later in the day and early chronotypes made music earlier in the day. Music performance and practice amount decreased during the COVID-19 period, but the daily timing of these activities did not change. All participants reported later sleep onset during the COVID-19 period; the amount of social interaction decreased during the COVID-19 period, while exercise increased for some and decreased for others. No changes in the daily timing of exercise, social interaction, or morning wake-up were reported. These findings suggest that performing musicians may be slightly earlier chronotypes than non-performing musicians and non-musicians, despite music performances often occurring in the evening. Chronotype was related to the time of day of music-making independent of nightly sleep timing, suggesting that times of day for making music reflect an individual's circadian rhythm.

scholarly journals Time-of-day-dependent responses of cyanobacterial cellular viability against oxidative stress

2019 ◽  
Author(s):  
Kenya Tanaka ◽  
Ginga Shimakawa ◽  
Shuji Nakanishi
Keyword(s):  
Oxidative Stress ◽  
Circadian Rhythms ◽  
Cell Viability ◽  
Circadian Clock ◽  
Stress Tolerance ◽  
Time Of Day ◽  
Circadian Oscillation ◽  
Subjective Time ◽  
Rhythmic Pattern ◽  
Oxidative Stress Tolerance

AbstractAs an adaptation to periodic fluctuations of environmental light, photosynthetic organisms have evolved a circadian clock. Control by the circadian clock of many cellular physiological functions, including antioxidant enzymes, metabolism and the cell cycle, has attracted attention in the context of oxidative stress tolerance. However, since each physiological function works in an integrated manner to deal with oxidative stress, whether or not cell responses to oxidative stress are under circadian control remains an open question. In fact, circadian rhythms of oxidative stress tolerance have not yet been experimentally demonstrated. In the present work, we applied an assay using methyl viologen (MV), which generates reactive oxygen species (ROS) under light irradiation, and experimentally verified the circadian rhythms of oxidative stress tolerance in photosynthetic cells of the cyanobacterium Synechococcus elongatus PCC7942, a standard model species for investigation of the circadian clock. Here, we report that ROS generated by MV treatment causes damage to stroma components and not to the photosynthetic electron transportation chain, leading to reduced cell viability. The degree of decrease in cell viability was dependent on the subjective time at which oxidative stress was applied. Thus, oxidative stress tolerance was shown to exhibit circadian rhythms. In addition, the rhythmic pattern of oxidative stress tolerance disappeared in mutant cells lacking the essential clock genes. Notably, ROS levels changed periodically, independent of the MV treatment. Thus, we demonstrate for the first time that in cyanobacterial cells, oxidative stress tolerance shows circadian oscillation.

scholarly journals Free-running circadian breathing rhythms are eliminated by suprachiasmatic nucleus lesion

2020 ◽  
Vol 129 (1) ◽  
pp. 49-57
Author(s):  
Benton S. Purnell ◽  
Gordon F. Buchanan
Keyword(s):  
Sleep Apnea ◽  
Circadian Rhythms ◽  
Suprachiasmatic Nucleus ◽  
Time Of Day ◽  
Sudden Unexpected Death ◽  
Constant Darkness ◽  
Unexpected Death ◽  
Treatment And Prevention ◽  
Free Running

It has long been appreciated that breathing is altered by time of day. This study demonstrates that rhythmicity in breathing persists in constant darkness but is dependent on the suprachiasmatic nucleus in the hypothalamus. Understanding circadian rhythms in breathing may be important for the treatment and prevention of diseases such as sleep apnea and sudden unexpected death in epilepsy.

scholarly journals INTEREST GROUP SESSION—SLEEP, CIRCADIAN RHYTHMS AND AGING INTEREST GROUP: SLEEP, PHYSICAL ACTIVITY, AND BRAIN AGING

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S402-S403
Author(s):  
Christopher N Kaufmann ◽  
Katie L Stone
Keyword(s):  
Circadian Rhythms ◽  
Sleep Disturbance ◽  
Interest Group ◽  
Cognitive Aging ◽  
Brain Aging ◽  
Disease Risk ◽  
Activity Patterns ◽  
Time Of Day ◽  
Daytime Activity ◽  
Dementia Prevention

Abstract As the US population ages, the prevalence of Alzheimer’s Disease (AD) and related dementias is expected to increase, making dementia prevention efforts a major public health priority. Impaired sleep and circadian rhythms, along with other lifestyle factors, have emerged as important modifiable disease risk factors—recent studies demonstrate the importance of sleep in preventing the development of key biomarkers for AD/dementia pathology. In this symposium, we will highlight findings on the associations of sleep, circadian rhythm disruptions, and daytime activity patterns on development of cognitive decline and dementia, exploring not only the mechanisms driving these associations, but the potential impact of sleep and lifestyle interventions in promoting healthy brain aging. The symposium consists of four presentations which use data from large national cohort studies. First, we will present analyses on patterns of 24-hour (circadian) activity rhythms (e.g., usual time of day for peak activity, regularity of circadian patterns) and incident dementia risk. The second presentation will present findings pertaining to understanding the link between sleep disturbance and inflammation (a substantial contributor to cognitive aging). The third will examine whether detailed daytime activity patterns associate with imaging-based brain volumes, independent of sleep disturbance. The final presentation will explore whether initiation of sleep disorder treatments may have the potential to change trajectories of cognitive performance as individuals age. Overall, the symposium will highlight the importance of sleep and activity patterns to brain health and stimulate discussion about improving sleep and circadian disruption as a target for dementia prevention efforts.

scholarly journals Circadian Control of Kisspeptin and a Gated GnRH Response Mediate the Preovulatory Luteinizing Hormone Surge

Endocrinology ◽  
2010 ◽  
Vol 152 (2) ◽  
pp. 595-606 ◽  
Author(s):  
Wilbur P. Williams ◽  
Stephan G. Jarjisian ◽  
Jens D. Mikkelsen ◽  
Lance J. Kriegsfeld
Keyword(s):  
Neural Circuit ◽  
Time Of Day ◽  
Circadian System ◽  
Cellular Activity ◽  
Lh Surge ◽  
Gating Mechanism ◽  
Circadian Control ◽  
Maximal Sensitivity ◽  
Luteinizing Hormone Surge ◽  
Daily Changes

Abstract In spontaneously ovulating rodents, the preovulatory LH surge is initiated on the day of proestrus by a timed, stimulatory signal originating from the circadian clock in the suprachiasmatic nucleus (SCN). The present studies explored whether kisspeptin is part of the essential neural circuit linking the SCN to the GnRH system to stimulate ovulation in Syrian hamsters (Mesocricetus auratus). Kisspeptin neurons exhibit an estrogen-dependent, daily pattern of cellular activity consistent with a role in the circadian control of the LH surge. The SCN targets kisspeptin neurons via vasopressinergic (AVP), but not vasoactive intestinal polypeptide-ergic, projections. Because AVP administration can only stimulate the LH surge during a restricted time of day, we examined the possibility that the response to AVP is gated at the level of kisspeptin and/or GnRH neurons. Kisspeptin and GnRH activation were assessed after the administration of AVP during the morning (when AVP is incapable of initiating the LH surge) and the afternoon (when AVP injections stimulate the LH surge). Kisspeptin, but not GnRH, cellular activity was up-regulated after morning injections of AVP, suggesting that time-dependent sensitivity to SCN signaling is gated within GnRH but not kisspeptin neurons. In support of this possibility, we found that the GnRH system exhibits pronounced daily changes in sensitivity to kisspeptin stimulation, with maximal sensitivity in the afternoon. Together these studies reveal a novel mechanism of ovulatory control with interactions among the circadian system, kisspeptin signaling, and a GnRH gating mechanism of control.

scholarly journals Day to Day Variability and Reliability of Blood Oxidative Stress Markers within a Four-Week Period in Healthy Young Men

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
A. H. Goldfarb ◽  
R. S. Garten ◽  
J. Waller ◽  
J. D. Labban
Keyword(s):  
Oxidative Stress ◽  
Xanthine Oxidase ◽  
Time Of Day ◽  
Protein Carbonyls ◽  
Young Cohort ◽  
Oxidative Stress Markers ◽  
Stress Markers ◽  
Intraclass Correlations ◽  
Daily Changes ◽  
Apparently Healthy

The present study aimed to determine the day to day variability and reliability of several blood oxidative stress markers at rest in a healthy young cohort over a four-week period. Twelve apparently healthy resistance trained males (24.6 ± 3.0 yrs) were tested over 7 visits within 4 weeks with at least 72 hrs between visits at the same time of day. Subjects rested 30 minutes prior to blood being obtained by vacutainer. Results. The highest IntraClass correlations (ICC’s) were obtained for protein carbonyls (PC) and oxygen radical absorbance capacity (ORAC) (PC = 0.785 and ORAC = 0.780). Cronbach’s α reliability score for PC was 0.967 and for ORAC was 0.961. The ICC’s for GSH, GSSG, and the GSSG/TGH ratio ICC were 0.600, 0.573, and 0.570, respectively, with Cronbach’s α being 0.913, 0.904, and 0.903, respectively. Xanthine oxidase ICC was 0.163 and Cronbach’s α was 0.538. Conclusions. PC and ORAC demonstrated good to excellent reliability while glutathione factors had poor to excellent reliability. Xanthine oxidase showed poor reliability and high variability. These results suggest that the PC and ORAC markers were the most stable and reliable oxidative stress markers in blood and that daily changes across visits should be considered when interpreting resting blood oxidative stress markers.

scholarly journals Physiological responses to food intake throughout the day

2014 ◽  
Vol 27 (1) ◽  
pp. 107-118 ◽  
Author(s):  
Jonathan D. Johnston
Keyword(s):  
Circadian Rhythms ◽  
Unmet Need ◽  
Time Of Day ◽  
Research Field ◽  
Biological Data ◽  
Model Systems ◽  
Physiological Processes ◽  
Circadian Timing System ◽  
Glucose Profiles ◽  
Molecular Components

Circadian rhythms act to optimise many aspects of our biology and thereby ensure that physiological processes are occurring at the most appropriate time. The importance of this temporal control is demonstrated by the strong associations between circadian disruption, morbidity and disease pathology. There is now a wealth of evidence linking the circadian timing system to metabolic physiology and nutrition. Relationships between these processes are often reciprocal, such that the circadian system drives temporal changes in metabolic pathways and changes in metabolic/nutritional status alter core molecular components of circadian rhythms. Examples of metabolic rhythms include daily changes in glucose homeostasis, insulin sensitivity and postprandial response. Time of day alters lipid and glucose profiles following individual meals whereas, over a longer time scale, meal timing regulates adiposity and body weight; these changes may occur via the ability of timed feeding to synchronise local circadian rhythms in metabolically active tissues. Much of the work in this research field has utilised animal and cellular model systems. Although these studies are highly informative and persuasive, there is a largely unmet need to translate basic biological data to humans. The results of such translational studies may open up possibilities for using timed dietary manipulations to help restore circadian synchrony and downstream physiology. Given the large number of individuals with disrupted rhythms due to, for example, shift work, jet-lag, sleep disorders and blindness, such dietary manipulations could provide widespread improvements in health and also economic performance.

scholarly journals Circadian Clock and The Cardiometabolic Risk

2010 ◽  
Vol 2 (2) ◽  
pp. 16
Author(s):  
Anna Meiliana ◽  
Andi Wijaya
Keyword(s):  
Circadian Rhythms ◽  
Cardiometabolic Risk ◽  
Clock Genes ◽  
Epidemiological Data ◽  
Circadian System ◽  
Temporal Organization ◽  
Liver Fat ◽  
Peripheral Tissues ◽  
The Central Nervous System ◽  
Rotation Of The Earth

BACKGROUND: Epidemiological data reveal parallel trends of decreasing sleep duration and increases in metabolic disorders such as obesity, diabetes and hypertension. There is growing evidence that these trends are mechanistically related.CONTENT: The circadian system orchestrates the temporal organization of many aspects of physiology, including metabolism, in synchrony with the 24 hours rotation of the Earth. The circadian system is a complex feedback network that involves interactions between the central nervous system and peripheral tissues. Circadian regulation is intimately linked to metabolic homeostasis and that dysregulation of circadian rhythms can contribute to disease. Conversely, metabolic signals also feed back into the circadian system, modulating circadian gene expression and behavior.SUMMARY: Both inter- and intraorgan desynchrony may be involved in the pathogenesis of cardiometabolic disease attributable to effects in brain and multiple metabolic tissues including heart, liver, fat, muscle, pancreas and gut. Efforts to dissect the molecular mediators that coordinate circadian, metabolic, and cardiovascular systems may ultimately lead to both improved therapeutics and preventive interventions.KEYWORDS: circadian rhythms, clock genes, nuclear receptor, sleep, obesity, cardiometabolic risk

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