Faculty Opinions recommendation of Daily rhythms of food-anticipatory behavioral activity do not require the known circadian clock.

2009 ◽  
Author(s):  
Ralph Mistlberger
Keyword(s):  
Circadian Clock ◽  
Behavioral Activity ◽  
Daily Rhythms

scholarly journals The circadian clock uses different environmental time cues to synchronize emergence and locomotion of the solitary bee Osmia bicornis

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Katharina Beer ◽  
Mariela Schenk ◽  
Charlotte Helfrich-Förster ◽  
Andrea Holzschuh
Keyword(s):  
Circadian Clock ◽  
Circadian System ◽  
Evolutionary Adaptation ◽  
Solitary Bee ◽  
Daily Rhythms ◽  
Osmia Bicornis ◽  
Cavity Nesting ◽  
Impact On Survival ◽  
Life On Earth ◽  
And Behavior

AbstractLife on earth adapted to the daily reoccurring changes in environment by evolving an endogenous circadian clock. Although the circadian clock has a crucial impact on survival and behavior of solitary bees, many aspects of solitary bee clock mechanisms remain unknown. Our study is the first to show that the circadian clock governs emergence in Osmia bicornis, a bee species which overwinters as adult inside its cocoon. Therefore, its eclosion from the pupal case is separated by an interjacent diapause from its emergence in spring. We show that this bee species synchronizes its emergence to the morning. The daily rhythms of emergence are triggered by temperature cycles but not by light cycles. In contrast to this, the bee’s daily rhythms in locomotion are synchronized by light cycles. Thus, we show that the circadian clock of O. bicornis is set by either temperature or light, depending on what activity is timed. Light is a valuable cue for setting the circadian clock when bees have left the nest. However, for pre-emerged bees, temperature is the most important cue, which may represent an evolutionary adaptation of the circadian system to the cavity-nesting life style of O. bicornis.

scholarly journals Daily rhythms in gene expression of the human parasite Schistosoma mansoni

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Kate A. Rawlinson ◽  
Adam J. Reid ◽  
Zhigang Lu ◽  
Patrick Driguez ◽  
Anna Wawer ◽  
...  
Keyword(s):  
Gene Expression ◽  
Schistosoma Mansoni ◽  
Circadian Clock ◽  
Drug Targets ◽  
Clock Genes ◽  
Biological Rhythms ◽  
Active Phase ◽  
Egg Laying ◽  
Daily Rhythms ◽  
Metazoan Parasites

Abstract Background The consequences of the earth’s daily rotation have led to 24-h biological rhythms in most organisms. Even some parasites are known to have daily rhythms, which, when in synchrony with host rhythms, can optimise their fitness. Understanding these rhythms may enable the development of control strategies that take advantage of rhythmic vulnerabilities. Recent work on protozoan parasites has revealed 24-h rhythms in gene expression, drug sensitivity and the presence of an intrinsic circadian clock; however, similar studies on metazoan parasites are lacking. To address this, we investigated if a metazoan parasite has daily molecular oscillations, whether they reveal how these longer-lived organisms can survive host daily cycles over a lifespan of many years and if animal circadian clock genes are present and rhythmic. We addressed these questions using the human blood fluke Schistosoma mansoni that lives in the vasculature for decades and causes the tropical disease schistosomiasis. Results Using round-the-clock transcriptomics of male and female adult worms collected from experimentally infected mice, we discovered that ~ 2% of its genes followed a daily pattern of expression. Rhythmic processes included a stress response during the host’s active phase and a ‘peak in metabolic activity’ during the host’s resting phase. Transcriptional profiles in the female reproductive system were mirrored by daily patterns in egg laying (eggs are the main drivers of the host pathology). Genes cycling with the highest amplitudes include predicted drug targets and a vaccine candidate. These 24-h rhythms may be driven by host rhythms and/or generated by a circadian clock; however, orthologs of core clock genes are missing and secondary clock genes show no 24-h rhythmicity. Conclusions There are daily rhythms in the transcriptomes of adult S. mansoni, but they appear less pronounced than in other organisms. The rhythms reveal temporally compartmentalised internal processes and host interactions relevant to within-host survival and between-host transmission. Our findings suggest that if these daily rhythms are generated by an intrinsic circadian clock then the oscillatory mechanism must be distinct from that in other animals. We have shown which transcripts oscillate at this temporal scale and this will benefit the development and delivery of treatments against schistosomiasis.

scholarly journals The Circadian Clock, the Brain, and COVID-19: The Cases of Olfaction and the Timing of Sleep

2021 ◽  
pp. 074873042110312
Author(s):  
Rachel S. Herz ◽  
Erik D. Herzog ◽  
Martha Merrow ◽  
Sara B. Noya
Keyword(s):  
Ischemic Stroke ◽  
Cognitive Function ◽  
Human Brain ◽  
Circadian Clock ◽  
Clinical Data ◽  
Circadian Clocks ◽  
Olfactory Sensitivity ◽  
Daily Rhythms ◽  
Sense Of Smell ◽  
The Brain

Daily rhythms of behavior and neurophysiology are integral to the circadian clocks of all animals. Examples of circadian clock regulation in the human brain include daily rhythms in sleep-wake, cognitive function, olfactory sensitivity, and risk for ischemic stroke, all of which overlap with symptoms displayed by many COVID-19 patients. Motivated by the relatively unexplored, yet pervasive, overlap between circadian functions and COVID-19 neurological symptoms, this perspective piece uses daily variations in the sense of smell and the timing of sleep and wakefulness as illustrative examples. We propose that time-stamping clinical data and testing may expand and refine diagnosis and treatment of COVID-19.

scholarly journals The opposing Chloride Cotransporters KCC and NKCC control locomotor activity in constant light and during long days

2021 ◽  
Author(s):  
Anna Katharina Eick ◽  
Maite Ogueta ◽  
Edgar Buhl ◽  
James J. L. Hodge ◽  
Ralf Stanewsky
Keyword(s):  
Locomotor Activity ◽  
Circadian Clock ◽  
Opposite Effect ◽  
Neuronal Response ◽  
Reversal Potential ◽  
Ion Concentration ◽  
Day Length ◽  
Constant Light ◽  
Behavioral Activity ◽  
Dependent Manner

AbstractCation Chloride Cotransporters (CCC’s) regulate intracellular chloride ion concentration ([Cl−]i) within neurons, which can reverse the direction of the neuronal response to the neurotransmitter GABA. Na+ K+ Cl− (NKCC) and K+ Cl− (KCC) cotransporters transport Cl− into or out of the cell, respectively. When NKCC activity dominates, the resulting high [Cl−]i can lead to an excitatory and depolarizing response of the neuron upon GABAA receptor opening, while KCC dominance has the opposite effect. This inhibitory-to-excitatory GABA switch has been linked to seasonal adaption of circadian clock function to changing day length, and its dysregulation is associated with neurodevelopmental disorders such as epilepsy. Constant light normally disrupts circadian clock function and leads to arrhythmic behavior. Here, we demonstrate a function for KCC in regulating Drosophila locomotor activity and GABA responses in circadian clock neurons because alteration of KCC expression in circadian clock neurons elicits rhythmic behavior in constant light. We observed the same effects after downregulation of the Wnk and Fray kinases, which modulate CCC activity in a [Cl−]i-dependent manner. Patch-clamp recordings from clock neurons show that downregulation of KCC results in a more positive GABA reversal potential, while KCC overexpression has the opposite effect. Finally, KCC downregulation represses morning behavioral activity during long photoperiods, while downregulation of NKCC promotes morning activity. In summary, our results support a model in which the regulation of [Cl−]i by a KCC/NKCC/Wnk/Fray feedback loop determines the response of clock neurons to GABA, which is important for adjusting behavioral activity to constant light and long-day conditions.

scholarly journals The Circadian Clock, Light, and Cryptochrome Regulate Feeding and Metabolism in Drosophila

2011 ◽  
Vol 26 (6) ◽  
pp. 497-506 ◽  
Author(s):  
Daniel J. Seay ◽  
Carl S. Thummel
Keyword(s):  
Circadian Clock ◽  
Feeding Behavior ◽  
Critical Role ◽  
Fruit Fly ◽  
Lipid Homeostasis ◽  
Dependent Manner ◽  
Daily Rhythms ◽  
Circadian Control ◽  
Carbohydrate Levels ◽  
Feeding Bout

Recent studies in mammals have demonstrated a central role for the circadian clock in maintaining metabolic homeostasis. In spite of these advances, however, little is known about how these complex pathways are coordinated. Here, we show that fundamental aspects of the circadian control of metabolism are conserved in the fruit fly Drosophila. We assay feeding behavior and basic metabolite levels in individual flies and show that, like mammals, Drosophila display a rapid increase in circulating sugar following a meal, which is subsequently stored in the form of glycogen. These daily rhythms in carbohydrate levels are disrupted in clock mutants, demonstrating a critical role for the circadian clock in the postprandial response to feeding. We also show that basic metabolite levels are coordinated in a clock-dependent manner and that clock function is required to maintain lipid homeostasis. By examining feeding behavior, we show that flies feed primarily during the first 4 hours of the day and that light suppresses a late day feeding bout through the cryptochrome photoreceptor. These studies demonstrate that central aspects of feeding and metabolism are dependent on the circadian clock in Drosophila. Our work also uncovers novel roles for light and cryptochrome on both feeding behavior and metabolism.

scholarly journals Resynchronization Dynamics Reveal that the Ventral Entrains the Dorsal Suprachiasmatic Nucleus

2016 ◽  
Vol 32 (1) ◽  
pp. 35-47 ◽  
Author(s):  
Stephanie R. Taylor ◽  
Thomas J. Wang ◽  
Daniel Granados-Fuentes ◽  
Erik D. Herzog
Keyword(s):  
Circadian Clock ◽  
Computational Model ◽  
Suprachiasmatic Nucleus ◽  
Computational Methods ◽  
Direct Evidence ◽  
Cell Communication ◽  
Experimental Results ◽  
Daily Rhythms ◽  
Phase Amplitude ◽  
Cell Cell

Although the suprachiasmatic nucleus (SCN) has long been considered the master circadian clock in mammals, the topology of the connections that synchronize daily rhythms among SCN cells is not well understood. We combined experimental and computational methods to infer the directed interactions that mediate circadian synchrony between regions of the SCN. We analyzed PERIOD2 (PER2) expression from SCN slices during and after treatment with tetrodotoxin, allowing us to map connections as cells resynchronized their daily cycling following blockade and restoration of cell-cell communication. Using automated analyses, we found that cells in the dorsal SCN stabilized their periods slower than those in the ventral SCN. A phase-amplitude computational model of the SCN revealed that, to reproduce the experimental results: (1) the ventral SCN had to be more densely connected than the dorsal SCN and (2) the ventral SCN needed strong connections to the dorsal SCN. Taken together, these results provide direct evidence that the ventral SCN entrains the dorsal SCN in constant conditions.

scholarly journals Circadian rhythm and neurodegenerative disorders

2020 ◽  
Vol 6 (2) ◽  
pp. 71-80
Author(s):  
Michelle Werdann ◽  
Yong Zhang
Keyword(s):  
Circadian Rhythm ◽  
Early Intervention ◽  
Circadian Rhythms ◽  
Neurodegenerative Diseases ◽  
Circadian Clock ◽  
Neurodegenerative Disorders ◽  
Circadian Clocks ◽  
Daily Rhythms ◽  
Animal Physiology ◽  
And Behavior

The circadian clock controls daily rhythms in animal physiology, metabolism, and behavior, such as the sleep‐wake cycle. Disruption of circadian rhythms has been revealed in many diseases including neurodegenerative disorders. Interestingly, patients with many neurodegenerative diseases often show problems with circadian clocks even years before other symptoms develop. Here we review the recent studies identifying the association between circadian rhythms and several major neurodegenerative disorders. Early intervention of circadian rhythms may benefit the treatment of neurodegeneration.

scholarly journals Ticking over: Circadian systems across the kingdoms of life

2011 ◽  
Vol 33 (1) ◽  
pp. 12-15
Author(s):  
Neil Dalchau ◽  
Alex A.R. Webb
Keyword(s):  
Circadian Clock ◽  
Model Organisms ◽  
Molecular Architecture ◽  
General Phenomenon ◽  
Daily Rhythms ◽  
Fitness Benefits ◽  
Multidisciplinary Studies ◽  
The Many

The ability to anticipate the day–night cycle and direct physiology accordingly has proven to be a general phenomenon across all kingdoms of life. Considerable fitness benefits are conferred by an internal 24hour clock, which is known as a circadian clock. Extensive multidisciplinary studies in a range of model organisms have elucidated many of the components involved in generating and sustaining daily rhythms. When comparing the circadian systems across the kingdoms, it is fascinating to observe the commonalities and differences in their molecular architecture, and the many adaptations which have evolved to deal with organismspecific requirements of biological timing.

Sign in / Sign up

Export Citation Format

Share Document