scholarly journals The lateral posterior clock neurons (LPN) of Drosophila melanogaster express three neuropeptides and have multiple connections within the circadian clock network and beyond

2021 ◽  
Author(s):  
Nils Reinhard ◽  
Enrico Bertolini ◽  
Aika Saito ◽  
Manabu Sekiguchi ◽  
Taishi Yoshii ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Circadian Clock ◽  
Clock Network ◽  
Lateral Posterior

scholarly journals Peripheral Sensory Organs Contribute to Temperature Synchronization of the Circadian Clock in Drosophila melanogaster

2021 ◽  
Vol 12 ◽  
Author(s):  
Rebekah George ◽  
Ralf Stanewsky
Keyword(s):  
Gene Expression ◽  
Drosophila Melanogaster ◽  
Circadian Clock ◽  
Temperature Fluctuations ◽  
Fruit Fly ◽  
Circadian Clocks ◽  
Sensory Cells ◽  
Clock Gene Expression ◽  
External Time ◽  
Peripheral Sensory

Circadian clocks are cell-autonomous endogenous oscillators, generated and maintained by self-sustained 24-h rhythms of clock gene expression. In the fruit fly Drosophila melanogaster, these daily rhythms of gene expression regulate the activity of approximately 150 clock neurons in the fly brain, which are responsible for driving the daily rest/activity cycles of these insects. Despite their endogenous character, circadian clocks communicate with the environment in order to synchronize their self-sustained molecular oscillations and neuronal activity rhythms (internal time) with the daily changes of light and temperature dictated by the Earth’s rotation around its axis (external time). Light and temperature changes are reliable time cues (Zeitgeber) used by many organisms to synchronize their circadian clock to the external time. In Drosophila, both light and temperature fluctuations robustly synchronize the circadian clock in the absence of the other Zeitgeber. The complex mechanisms for synchronization to the daily light–dark cycles are understood with impressive detail. In contrast, our knowledge about how the daily temperature fluctuations synchronize the fly clock is rather limited. Whereas light synchronization relies on peripheral and clock-cell autonomous photoreceptors, temperature input to the clock appears to rely mainly on sensory cells located in the peripheral nervous system of the fly. Recent studies suggest that sensory structures located in body and head appendages are able to detect temperature fluctuations and to signal this information to the brain clock. This review will summarize these studies and their implications about the mechanisms underlying temperature synchronization.

Extra-retinal photoreceptors synchronise the circadian clock of Drosophila melanogaster.

2003 ◽  
Vol 2003 (Spring) ◽  
Author(s):  
Shobi Veleri ◽  
Charlotte Helfrich-Förster ◽  
Ralf Stanewsky
Keyword(s):  
Drosophila Melanogaster ◽  
Circadian Clock ◽  
Retinal Photoreceptors

scholarly journals Sympathetic Activation Induces Skeletal Fgf23 Expression in a Circadian Rhythm-dependent Manner

2013 ◽  
Vol 289 (3) ◽  
pp. 1457-1466 ◽  
Author(s):  
Masanobu Kawai ◽  
Saori Kinoshita ◽  
Shigeki Shimba ◽  
Keiichi Ozono ◽  
Toshimi Michigami
Keyword(s):  
Food Intake ◽  
Circadian Clock ◽  
Sympathetic Tone ◽  
Dark Phase ◽  
Dependent Manner ◽  
Phosphate Metabolism ◽  
Sympathetic Activation ◽  
Clock Network

The circadian clock network is well known to link food intake and metabolic outputs. Phosphorus is a pivotal nutritional factor involved in energy and skeletal metabolisms and possesses a circadian profile in the circulation; however, the precise mechanisms whereby phosphate metabolism is regulated by the circadian clock network remain largely unknown. Because sympathetic tone, which displays a circadian profile, is activated by food intake, we tested the hypothesis that phosphate metabolism was regulated by the circadian clock network through the modification of food intake-associated sympathetic activation. Skeletal Fgf23 expression showed higher expression during the dark phase (DP) associated with elevated circulating FGF23 levels and enhanced phosphate excretion in the urine. The peaks in skeletal Fgf23 expression and urine epinephrine levels, a marker for sympathetic tone, shifted from DP to the light phase (LP) when mice were fed during LP. Interestingly, β-adrenergic agonist, isoproterenol (ISO), induced skeletal Fgf23 expression when administered at ZT12, but this was not observed in Bmal1-deficient mice. In vitro reporter assays revealed that ISO trans-activated Fgf23 promoter through a cAMP responsive element in osteoblastic UMR-106 cells. The mechanism of circadian regulation of Fgf23 induction by ISO in vivo was partly explained by the suppressive effect of Cryptochrome1 (Cry1) on ISO signaling. These results indicate that the regulation of skeletal Fgf23 expression by sympathetic activity is dependent on the circadian clock system and may shed light on new regulatory networks of FGF23 that could be important for understanding the physiology of phosphate metabolism.

scholarly journals A spatial model of the plant circadian clock reveals design principles for coordinated timing under noisy environments

2020 ◽  
Author(s):  
Mark Greenwood ◽  
Isao T. Tokuda ◽  
James C.W. Locke
Keyword(s):  
Gene Expression ◽  
Circadian Clock ◽  
Genetic Network ◽  
Design Principles ◽  
Individual Plant ◽  
Coupling Mechanism ◽  
Mrna Levels ◽  
Cell Coupling ◽  
Noisy Environments ◽  
Clock Network

AbstractIndividual plant cells possess a genetic network, the circadian clock, that times internal processes to the day-night cycle. Mathematical models of the clock network have driven a mechanistic understanding of the clock in plants. However, these models are typically either ‘whole plant’ models that ignore tissue or cell type specific clock behavior, or ‘phase only’ models that do not include clock network components explicitly. It is increasingly clear that in order to reveal the design principles of the plant circadian clock, clock network models must address spatial differences. This is because complex spatial behaviours have been observed in tissues and cells in plants, including period and phase differences between cells and spatial waves of gene expression between organs. Here, we implement an up to date clock network model on a spatial template of the plant. In our model, the sensitivity to light inputs varies across the plant, and cells communicate their clock timing locally via the levels of core clock mRNA levels by cell-to-cell coupling. We found that differences in sensitivities to environmental input in the model can explain the experimentally observed differences in clock periods in different organs, and we show using the model that a plausible coupling mechanism can generate the experimentally observed waves in clock gene expression across the plant. We then examined what features of the plant circadian system allow it to keep time under noisy light-dark (LD) cycles. We found that differences in sensitivity to light can allow regional flexibility in phase even under LD cycles, whilst local cell-to-cell coupling minimized variability in clock rhythms in neighboring cells. Thus, local sensitivity to environmental inputs combined with cell-to-cell coupling allows for flexible yet robust circadian timing under noisy environments.

Sign in / Sign up

Export Citation Format

Share Document