scholarly journals A clock in mouse cones contributes to the retinal oscillator network and to synchronization of the circadian system

2020 ◽  
Author(s):  
Cristina Sandu ◽  
Prapimpun Wongchitrat ◽  
Nadia Mazzaro ◽  
Catherine Jaeger ◽  
Hugo Calligaro ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Circadian System ◽  
Mouse Retina ◽  
Cone Photoreceptor ◽  
Light Entrainment ◽  
Circadian Organization ◽  
Rhythmic Gene ◽  
Central Clock ◽  
Oscillator Network ◽  
Photic Input

AbstractMultiple circadian clocks dynamically regulate mammalian physiology. In retina, rhythmic gene expression serves to align vision and tissue homeostasis with daily light changes. Photic input is relayed to the suprachiasmatic nucleus to entrain the master clock, which matches behaviour to environmental changes. Circadian organization of the mouse retina involves coordinated, layer-specific oscillators, but so far little is known about the cone photoreceptor clock and its role in the circadian system. Using the cone-only Nrl-/- mouse model we show that cones contain a functional self-sustained molecular clockwork. By bioluminescence-combined imaging we also show that cones provide substantial input to the retinal clock network. Furthermore, we found that light entrainment and negative masking in cone-only mice are subtly altered and that constant light displayed profound effects on their central clock. Thus, our study demonstrates the contribution of cones to retinal circadian organisation and their role in finely tuning behaviour to environmental conditions.

scholarly journals Genome-wide correlation analysis to identify amplitude regulators of circadian transcriptome output

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Evan S. Littleton ◽  
Madison L. Childress ◽  
Michaela L. Gosting ◽  
Ayana N. Jackson ◽  
Shihoko Kojima
Keyword(s):  
Clock Genes ◽  
Circadian System ◽  
Average Level ◽  
Relative Amplitude ◽  
Critical Component ◽  
Period 2 ◽  
Genome Wide ◽  
Mouse Tissues ◽  
Rhythmic Gene ◽  
Insight Into

AbstractCell-autonomous circadian system, consisting of core clock genes, generates near 24-h rhythms and regulates the downstream rhythmic gene expression. While it has become clear that the percentage of rhythmic genes varies among mouse tissues, it remains unclear how this variation can be generated, particularly when the clock machinery is nearly identical in all tissues. In this study, we sought to characterize circadian transcriptome datasets that are publicly available and identify the critical component(s) involved in creating this variation. We found that the relative amplitude of 13 genes and the average level of 197 genes correlated with the percentage of cycling genes. Of those, the correlation of Rorc in both relative amplitude and the average level was one of the strongest. In addition, the level of Per2AS, a novel non-coding transcript that is expressed at the Period 2 locus, was also linearly correlated, although with a much lesser degree compared to Rorc. Overall, our study provides insight into how the variation in the percentage of clock-controlled genes can be generated in mouse tissues and suggests that Rorc and potentially Per2AS are involved in regulating the amplitude of circadian transcriptome output.

scholarly journals Chronothyroidology: Chronobiological Aspects in Thyroid Function and Diseases

Life ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 426
Author(s):  
Giuseppe Bellastella ◽  
Maria Ida Maiorino ◽  
Lorenzo Scappaticcio ◽  
Annamaria De Bellis ◽  
Silvia Mercadante ◽  
...  
Keyword(s):  
Thyroid Function ◽  
Biological Rhythms ◽  
Cellular Level ◽  
Scientific Discipline ◽  
Biological Phenomena ◽  
Pituitary Thyroid Axis ◽  
Circadian Organization ◽  
Thyroid Axis ◽  
Central Clock ◽  
Thyroid Dysfunctions

Chronobiology is the scientific discipline which considers biological phenomena in relation to time, which assumes itself biological identity. Many physiological processes are cyclically regulated by intrinsic clocks and many pathological events show a circadian time-related occurrence. Even the pituitary–thyroid axis is under the control of a central clock, and the hormones of the pituitary–thyroid axis exhibit circadian, ultradian and circannual rhythmicity. This review, after describing briefly the essential principles of chronobiology, will be focused on the results of personal experiences and of other studies on this issue, paying particular attention to those regarding the thyroid implications, appearing in the literature as reviews, metanalyses, original and observational studies until 28 February 2021 and acquired from two databases (Scopus and PubMed). The first input to biological rhythms is given by a central clock located in the suprachiasmatic nucleus (SCN), which dictates the timing from its hypothalamic site to satellite clocks that contribute in a hierarchical way to regulate the physiological rhythmicity. Disruption of the rhythmic organization can favor the onset of important disorders, including thyroid diseases. Several studies on the interrelationship between thyroid function and circadian rhythmicity demonstrated that thyroid dysfunctions may affect negatively circadian organization, disrupting TSH rhythm. Conversely, alterations of clock machinery may cause important perturbations at the cellular level, which may favor thyroid dysfunctions and also cancer.

scholarly journals A QTL on Chromosome 10 Modulates Cone Photoreceptor Number in the Mouse Retina

2011 ◽  
Vol 52 (6) ◽  
pp. 3228 ◽  
Author(s):  
Irene E. Whitney ◽  
Mary A. Raven ◽  
Lu Lu ◽  
Robert W. Williams ◽  
Benjamin E. Reese
Keyword(s):  
Mouse Retina ◽  
Cone Photoreceptor ◽  
Chromosome 10

Functioning of the rat circadian system is modified by light applied in critical postnatal days

2001 ◽  
Vol 280 (4) ◽  
pp. R1023-R1030 ◽  
Author(s):  
M. M. Canal-Corretger ◽  
J. Vilaplana ◽  
T. Cambras ◽  
A. Díez-Noguera
Keyword(s):  
Light Pulse ◽  
Critical Period ◽  
Decisive Role ◽  
Circadian System ◽  
Constant Darkness ◽  
Biological Clocks ◽  
Critical Window ◽  
Lighting Conditions ◽  
Lactation Stage ◽  
Circadian Organization

Lighting conditions influence biological clocks. The present experiment was designed to test the presence of a critical window of days during the lactation stage of the rat in which light has a decisive role on the development of the circadian system. Rats were exposed to 4, 8, or 12 days of constant light (LL) during the first days of life. Their circadian rhythm was later studied under LL and constant darkness. The response to a light pulse was also examined. Results show that the greater the number of LL days during lactation, the stronger the rhythm under LL and the smaller the phase shift due to the light pulse. These responses are enhanced when rats are exposed to LL days around postnatal day 12. A mathematical model was built to explain the responses of the circadian system with respect to the timing of LL during lactation, and we deduced that between postnatal days 10 to 20there is a critical period of sensitivity to light; consequently, exposure to LL during this time modifies the circadian organization of the motor activity.

scholarly journals Local signals in mouse horizontal cell dendrites

2017 ◽  
Author(s):  
Camille A. Chapot ◽  
Christian Behrens ◽  
Luke E. Rogerson ◽  
Tom Baden ◽  
Sinziana Pop ◽  
...  
Keyword(s):  
Glutamate Release ◽  
Horizontal Cell ◽  
Horizontal Cells ◽  
Single Type ◽  
Mouse Retina ◽  
Gabaergic Interneuron ◽  
List Type ◽  
Cone Photoreceptor ◽  
Cone Photoreceptors ◽  
Temporal Properties

SummaryThe mouse retina contains a single type of horizontal cell, a GABAergic interneuron that samples from all cone photoreceptors within reach and modulates their glutamatergic output via parallel feedback mechanisms. Because horizontal cells form an electrically-coupled network, they have been implicated in global signal processing, such as large scale contrast enhancement. Recently, it has been proposed that horizontal cells can also act locally at the level of individual cone photoreceptors. To test this possibility physiologically, we used two-photon microscopy to record light stimulus-evoked Ca2+signals in cone axon terminals and horizontal cell dendrites as well as glutamate release in the outer plexiform layer. By selectively stimulating the two mouse cone opsins with green and UV light, we assessed whether signals from individual cones remain “isolated” within horizontal cell dendritic tips, or whether they spread across the dendritic arbour. Consistent with the mouse‘s opsin expression gradient, we found that the Ca2+signals recorded from dendrites of dorsal horizontal cells were dominated by M- and those of ventral horizontal cells by S-opsin activation. The signals measured in neighbouring horizontal cell dendritic tips varied markedly in their chromatic preference, arguing against global processing. Rather, our experimental data and results from biophysically realistic modelling support the idea that horizontal cells can process cone input locally, extending the “classical” view of horizontal cells function. Pharmacologically removing horizontal cells from the circuitry reduced the sensitivity of the cone signal to low frequencies, suggesting that local horizontal cell feedback shapes the temporal properties of cone output.HighlightsLight-evoked Ca2+signals in horizontal cell dendrites reflect opsin gradientChromatic preferences in neighbouring dendritic tips vary markedlyMouse horizontal cells process cone photoreceptor input locallyLocal horizontal cell feedback shapes the temporal properties of cone outputeTOC BlurbChapot et al. show that local light responses in mouse horizontal cell dendrites inherit properties, including chromatic preference, from the presynaptic cone photoreceptor, suggesting that their dendrites can provide “private” feedback to cones, for instance, to shape the temporal filtering properties of the cone synapse.

scholarly journals Adaptive diversification in the cellular circadian behavior of Arabidopsis leaf- and root-derived cells

2021 ◽  
Author(s):  
Shunji Nakamura ◽  
Tokitaka Oyama
Keyword(s):  
Environmental Changes ◽  
Cell Types ◽  
Cellular Level ◽  
Circadian System ◽  
Circadian Clocks ◽  
Intrinsic Properties ◽  
Adaptive Diversification ◽  
Local Environments ◽  
Fluctuating Environments ◽  
Circadian Behavior

The plant circadian system is based on self-sustained cellular oscillations and is utilized to adapt to daily and seasonal environmental changes. The cellular circadian clocks in the above- and belowground plant organs are subjected to diverse local environments. Individual cellular clocks are affected by other cells/tissues in plants, and the intrinsic properties of cellular clocks remain to be elucidated. In this study, we showed the circadian properties of leaf- and root-derived cells of a CCA1::LUC Arabidopsis transgenic plant and demonstrated that the cells in total isolation from other cells harbor a genuine circadian clock. Quantitative and statistical analyses for individual cellular bioluminescence rhythms revealed a difference in amplitude and precision of light/dark entrainment between the two cell-types, suggesting that leaf-derived cells have a clock with a stronger persistence against fluctuating environments. Circadian systems in the leaves and roots are diversified to adapt to their local environments at the cellular level.

scholarly journals Circadian immune circuits

2020 ◽  
Vol 218 (2) ◽  
Author(s):  
Miguel Palomino-Segura ◽  
Andrés Hidalgo
Keyword(s):  
Immune Responses ◽  
Immune Cells ◽  
Environmental Changes ◽  
Fundamental Property ◽  
Structural Elements ◽  
Host Immune Responses ◽  
Physiological Processes ◽  
Specific Antigens ◽  
Specific Receptors ◽  
Central Clock

Immune responses are gated to protect the host against specific antigens and microbes, a task that is achieved through antigen- and pattern-specific receptors. Less appreciated is that in order to optimize responses and to avoid collateral damage to the host, immune responses must be additionally gated in intensity and time. An evolutionary solution to this challenge is provided by the circadian clock, an ancient time-keeping mechanism that anticipates environmental changes and represents a fundamental property of immunity. Immune responses, however, are not exclusive to immune cells and demand the coordinated action of nonhematopoietic cells interspersed within the architecture of tissues. Here, we review the circadian features of innate immunity as they encompass effector immune cells as well as structural cells that orchestrate their responses in space and time. We finally propose models in which the central clock, structural elements, and immune cells establish multidirectional circadian circuits that may shape the efficacy and strength of immune responses and other physiological processes.

The neural circadian system of mammals

2011 ◽  
Vol 49 ◽  
pp. 1-17 ◽  
Author(s):  
Hugh D. Piggins ◽  
Clare Guilding
Keyword(s):  
Circadian Rhythms ◽  
Circadian System ◽  
Daily Activities ◽  
Suprachiasmatic Nuclei ◽  
Dark Cycle ◽  
Environmental Light ◽  
Endogenous Clock ◽  
Central Clock

Humans and other mammals exhibit a remarkable array of cyclical changes in physiology and behaviour. These are often synchronized to the changing environmental light–dark cycle and persist in constant conditions. Such circadian rhythms are controlled by an endogenous clock, located in the suprachiasmatic nuclei of the hypothalamus. This structure and its cells have unique properties, and some of these are reviewed to highlight how this central clock controls and sculpts our daily activities.

scholarly journals Evidences of Polymorphism Associated with Circadian System and Risk of Pathologies: A Review of the Literature

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
F. J. Valenzuela ◽  
J. Vera ◽  
C. Venegas ◽  
S. Muñoz ◽  
S. Oyarce ◽  
...  
Keyword(s):  
Cellular Proliferation ◽  
Metabolic Diseases ◽  
Environmental Changes ◽  
Clock Genes ◽  
Genetic Interaction ◽  
Circadian System ◽  
Feeding Time ◽  
Genetic Components ◽  
Molecular Components ◽  
Risk Of Cancer

The circadian system is a supraphysiological system that modulates different biological functions such as metabolism, sleep-wake, cellular proliferation, and body temperature. Different chronodisruptors have been identified, such as shift work, feeding time, long days, and stress. The environmental changes and our modern lifestyle can alter the circadian system and increase the risk of developing pathologies such as cancer, preeclampsia, diabetes, and mood disorder. This system is organized by transcriptional/tranductional feedback loops of clock genesClock,Bmal1,Per1–3,andCry1-2. How molecular components of the clock are able to influence the development of diseases and their risk relation with genetic components of polymorphism of clock genes is unknown. This research describes different genetic variations in the population and how these are associated with risk of cancer, metabolic diseases such as diabetes, obesity, and dyslipidemias, and also mood disorders such as depression, bipolar disease, excessive alcohol intake, and infertility. Finally, these findings will need to be implemented and evaluated at the level of genetic interaction and how the environment factors trigger the expression of these pathologies will be examined.

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