scholarly journals EYES ABSENT and TIMELESS integrate photoperiodic and temperature cues to regulate seasonal physiology in Drosophila

2020 ◽  
Author(s):  
Antoine Abrieux ◽  
Yongbo Xue ◽  
Yao Cai ◽  
Kyle M. Lewald ◽  
Hoang Nhu Nguyen ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Molecular Mechanisms ◽  
Environmental Changes ◽  
Physiological Responses ◽  
Day Length ◽  
Short Photoperiod ◽  
Eyes Absent ◽  
Winter Conditions ◽  
Clock Protein

AbstractOrganisms possess photoperiodic timing mechanisms to anticipate variations in day length and temperature as the seasons progress. The nature of the molecular mechanisms interpreting and signaling these environmental changes to elicit downstream neuroendocrine and physiological responses are just starting to emerge. Here, we demonstrate that in Drosophila melanogaster, EYES ABSENT (EYA) acts as a seasonal sensor by interpreting photoperiodic and temperature changes to trigger appropriate physiological responses. We observed that tissue-specific genetic manipulation of eya expression is sufficient to disrupt the ability of flies to sense seasonal cues, thereby altering the extent of female reproductive dormancy. Specifically we observed that EYA proteins, which peak at night in short photoperiod and accumulate at higher levels in the cold, promote reproductive dormancy in female D. melanogaster. Furthermore, we provide evidence indicating that the role of EYA in photoperiodism and temperature sensing is aided by the stabilizing action of the light-sensitive circadian clock protein TIMELESS (TIM). We postulate that increased stability and level of TIM at night under short photoperiod together with the production of cold-induced and light-insensitive TIM isoforms facilitate EYA accumulation in winter conditions. This is supported by our observations that tim null mutants exhibit reduced incidence of reproductive dormancy in simulated winter conditions, while flies overexpressing tim show an increased incidence of reproductive dormancy even in long photoperiod.Significance StatementExtracting information on calendar time from seasonal changes in photoperiod and temperature is critical for organisms to maintain circannual cycles in physiology and behavior. Here we found that in flies, EYES ABSENT (EYA) protein act as a seasonal sensor by adjusting its abundance and circadian phase in response to changes in photoperiod and temperature. We show that the manipulation of EYA levels is sufficient to impair the ability of female Drosophila to regulate seasonal variation in reproductive dormancy. Finally, our results suggest an important role of the circadian clock protein TIMELESS (TIM) in modulating EYA level through its ability to measure night length, linking the circadian clock to seasonal timing.

scholarly journals EYES ABSENT and TIMELESS integrate photoperiodic and temperature cues to regulate seasonal physiology inDrosophila

2020 ◽  
Vol 117 (26) ◽  
pp. 15293-15304 ◽  
Author(s):  
Antoine Abrieux ◽  
Yongbo Xue ◽  
Yao Cai ◽  
Kyle M. Lewald ◽  
Hoang Nhu Nguyen ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Environmental Changes ◽  
Genetic Manipulation ◽  
Physiological Responses ◽  
Day Length ◽  
Short Photoperiod ◽  
Eyes Absent ◽  
Temperature Changes ◽  
Winter Conditions ◽  
Timing Mechanisms

Organisms possess photoperiodic timing mechanisms to detect variations in day length and temperature as the seasons progress. The nature of the molecular mechanisms interpreting and signaling these environmental changes to elicit downstream neuroendocrine and physiological responses are just starting to emerge. Here, we demonstrate that, inDrosophila melanogaster, EYES ABSENT (EYA) acts as a seasonal sensor by interpreting photoperiodic and temperature changes to trigger appropriate physiological responses. We observed that tissue-specific genetic manipulation ofeyaexpression is sufficient to disrupt the ability of flies to sense seasonal cues, thereby altering the extent of female reproductive dormancy. Specifically, we observed that EYA proteins, which peak at night in short photoperiod and accumulate at higher levels in the cold, promote reproductive dormancy in femaleD. melanogaster. Furthermore, we provide evidence indicating that the role of EYA in photoperiodism and temperature sensing is aided by the stabilizing action of the light-sensitive circadian clock protein TIMELESS (TIM). We postulate that increased stability and level of TIM at night under short photoperiod together with the production of cold-induced and light-insensitive TIM isoforms facilitate EYA accumulation in winter conditions. This is supported by our observations thattimnull mutants exhibit reduced incidence of reproductive dormancy in simulated winter conditions, while flies overexpressingtimshow an increased incidence of reproductive dormancy even in long photoperiod.

scholarly journals The Role of Light and Circadian Clock in Regulation of Leaf Senescence

2021 ◽  
Vol 12 ◽  
Author(s):  
Juhyeon Lee ◽  
Myeong Hoon Kang ◽  
Jung Yeon Kim ◽  
Pyung Ok Lim
Keyword(s):  
Circadian Clock ◽  
Leaf Senescence ◽  
Regulatory Networks ◽  
Molecular Mechanisms ◽  
Environmental Changes ◽  
Control Plant ◽  
Structural Features ◽  
Clock Period ◽  
Environmental Signals

Leaf senescence is an integrated response of the cells to develop age information and various environmental signals. Thus, some of the genes involved in the response to environmental changes are expected to regulate leaf senescence. Light acts not only as the primary source of energy for photosynthesis but also as an essential environmental cue that directly control plant growth and development including leaf senescence. The molecular mechanisms linking light signaling to leaf senescence have recently emerged, exploring the role of Phytochrome-Interacting Factors (PIFs) as a central player leading to diverse senescence responses, senescence-promoting gene regulatory networks (GRNs) involving PIFs, and structural features of transcription modules in GRNs. The circadian clock is an endogenous time-keeping system for the adaptation of organisms to changing environmental signals and coordinates developmental events throughout the life of the plant. Circadian rhythms can be reset by environmental signals, such as light-dark or temperature cycles, to match the environmental cycle. Research advances have led to the discovery of the role of core clock components as senescence regulators and their underlying signaling pathways, as well as the age-dependent shortening of the circadian clock period. These discoveries highlight the close relationship between the circadian system and leaf senescence. Key issues remain to be elucidated, including the effect of light on leaf senescence in relation to the circadian clock, and the identification of key molecules linking aging, light, and the circadian clock, and integration mechanisms of various senescence-affecting signals at the multi-regulation levels in dynamics point of view.

scholarly journals Genome-wide fitness assessment during diurnal growth reveals an expanded role of the cyanobacterial circadian clock protein KaiA

2018 ◽  
Author(s):  
David G. Welkie ◽  
Benjamin E. Rubin ◽  
Yong-Gang Chang ◽  
Spencer Diamond ◽  
Scott A. Rifkin ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Environmental Changes ◽  
Time Of Day ◽  
Negative Regulator ◽  
Starvation Period ◽  
Night Time ◽  
Photosynthetic Organisms ◽  
Genetic Components ◽  
Clock Protein

AbstractThe recurrent pattern of light and darkness generated by Earth’s axial rotation has profoundly influenced the evolution of organisms, selecting for both biological mechanisms that respond acutely to environmental changes and circadian clocks that program physiology in anticipation of daily variations. The necessity to integrate environmental responsiveness and circadian programming is exemplified in photosynthetic organisms such as cyanobacteria, which depend on light-driven photochemical processes. The cyanobacterium Synechococcus elongatus PCC 7942 is an excellent model system for dissecting these entwined mechanisms. Its core circadian oscillator, consisting of three proteins KaiA, KaiB, and KaiC, transmits time-of-day signals to clock-output proteins, which reciprocally regulate global transcription. Research performed under constant light facilitates analysis of intrinsic cycles separately from direct environmental responses, but does not provide insight into how these regulatory systems are integrated during light-dark cycles. Thus, we sought to identify genes that are specifically necessary in a day-night environment. We screened a dense bar-coded transposon library in both continuous light and daily cycling conditions and compared the fitness consequences of loss of each nonessential gene in the genome. Although the clock itself is not essential for viability in light-dark cycles, the most detrimental mutations revealed by the screen were those that disrupt KaiA. The screen broadened our understanding of light-dark survival in photosynthetic organisms, identified unforeseen clock-protein interaction dynamics, and reinforced the role of the clock as a negative regulator of a night-time metabolic program that is essential for S. elongatus to survive in the dark.SignificanceUnderstanding how photosynthetic bacteria respond to and anticipate natural light–dark cycles is necessary for predictive modeling, bioengineering, and elucidating metabolic strategies for diurnal growth. Here, we identify the genetic components that are important specifically under light-dark cycling conditions and determine how a properly functioning circadian clock prepares metabolism for darkness, a starvation period for photoautotrophs. This study establishes that the core circadian clock protein KaiA is necessary to enable rhythmic de-repression of a night-time circadian program.

scholarly journals Genome-wide fitness assessment during diurnal growth reveals an expanded role of the cyanobacterial circadian clock protein KaiA

2018 ◽  
Vol 115 (30) ◽  
pp. E7174-E7183 ◽  
Author(s):  
David G. Welkie ◽  
Benjamin E. Rubin ◽  
Yong-Gang Chang ◽  
Spencer Diamond ◽  
Scott A. Rifkin ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Continuous Light ◽  
Axial Rotation ◽  
Time Of Day ◽  
Negative Regulator ◽  
Photosynthetic Organisms ◽  
Environmental Responsiveness ◽  
Environmental Responses ◽  
Clock Protein

The recurrent pattern of light and darkness generated by Earth’s axial rotation has profoundly influenced the evolution of organisms, selecting for both biological mechanisms that respond acutely to environmental changes and circadian clocks that program physiology in anticipation of daily variations. The necessity to integrate environmental responsiveness and circadian programming is exemplified in photosynthetic organisms such as cyanobacteria, which depend on light-driven photochemical processes. The cyanobacterium Synechococcus elongatus PCC 7942 is an excellent model system for dissecting these entwined mechanisms. Its core circadian oscillator, consisting of three proteins, KaiA, KaiB, and KaiC, transmits time-of-day signals to clock-output proteins, which reciprocally regulate global transcription. Research performed under constant light facilitates analysis of intrinsic cycles separately from direct environmental responses but does not provide insight into how these regulatory systems are integrated during light–dark cycles. Thus, we sought to identify genes that are specifically necessary in a day–night environment. We screened a dense bar-coded transposon library in both continuous light and daily cycling conditions and compared the fitness consequences of loss of each nonessential gene in the genome. Although the clock itself is not essential for viability in light–dark cycles, the most detrimental mutations revealed by the screen were those that disrupt KaiA. The screen broadened our understanding of light–dark survival in photosynthetic organisms, identified unforeseen clock–protein interaction dynamics, and reinforced the role of the clock as a negative regulator of a nighttime metabolic program that is essential for S. elongatus to survive in the dark.

scholarly journals CREB mediates the C. elegans dauer polyphenism through direct and cell-autonomous regulation of TGF-β expression

PLoS Genetics ◽  
2021 ◽  
Vol 17 (7) ◽  
pp. e1009678
Author(s):  
JiSoo Park ◽  
Hyekyoung Oh ◽  
Do-Young Kim ◽  
YongJin Cheon ◽  
Yeon-Ji Park ◽  
...  
Keyword(s):  
Developmental Plasticity ◽  
Molecular Mechanisms ◽  
Environmental Changes ◽  
Marker Gene ◽  
Camp Response Element Binding ◽  
Camp Response Element ◽  
Developmental Programs ◽  
C Elegans ◽  
Element Binding Protein

Animals can adapt to dynamic environmental conditions by modulating their developmental programs. Understanding the genetic architecture and molecular mechanisms underlying developmental plasticity in response to changing environments is an important and emerging area of research. Here, we show a novel role of cAMP response element binding protein (CREB)-encoding crh-1 gene in developmental polyphenism of C. elegans. Under conditions that promote normal development in wild-type animals, crh-1 mutants inappropriately form transient pre-dauer (L2d) larva and express the L2d marker gene. L2d formation in crh-1 mutants is specifically induced by the ascaroside pheromone ascr#5 (asc-ωC3; C3), and crh-1 functions autonomously in the ascr#5-sensing ASI neurons to inhibit L2d formation. Moreover, we find that CRH-1 directly binds upstream of the daf-7 TGF-β locus and promotes its expression in the ASI neurons. Taken together, these results provide new insight into how animals alter their developmental programs in response to environmental changes.

Role of medicinal plants against neurodegenerative diseases

2021 ◽  
Vol 22 ◽  
Author(s):  
Ritika Luthra ◽  
Arpita Roy
Keyword(s):  
Medicinal Plants ◽  
Neurodegenerative Diseases ◽  
Molecular Mechanisms ◽  
Environmental Changes ◽  
Inflammatory Responses ◽  
Vital Role ◽  
Significant Loss ◽  
Therapeutic Interventions ◽  
Inflammatory Stress

: Diseases with a significant loss of neurons, structurally and functionally are termed as neurodegenerative diseases. Due to the present therapeutic interventions and progressive nature of diseases, a variety of side effects have risen up, thus leading the patients to go for an alternative medication. The role of medicinal plants in such cases has been beneficial because of their exhibition via different cellular and molecular mechanisms. Alleviation in inflammatory responses, suppression of the functionary aspect of pro-inflammatory cytokines like a tumor, improvement in antioxidative properties is among few neuroprotective mechanisms of traditional plants. Variation in transcription and transduction pathways play a vital role in the preventive measures of plants in such diseases. Neurodegenerative diseases are generally caused by depletion of proteins, oxidative and inflammatory stress, environmental changes and so on, with aging being the most important cause. Natural compounds can be used in order to treat neurodegenerative diseases Medicinal plants such as Ginseng, Withania somnifera, Bacopa monnieri, Ginkgo biloba, etc. are some of the medicinal plants for prevention of neurological symptoms. This review deals with the use of different medicinal plants for the prevention of neurodegenerative diseases.

scholarly journals Physiological and Genetic Bases of the Circadian Clock in Plants and Their Relationship with Herbicides Efficacy

2016 ◽  
Vol 34 (1) ◽  
pp. 191-198
Author(s):  
G. DALAZEN ◽  
A. MEROTTO JR.
Keyword(s):  
Circadian Clock ◽  
Environmental Changes ◽  
Crop Yields ◽  
Light Availability ◽  
Leaf Angle ◽  
Time Of Application ◽  
Genetic Mechanisms ◽  
Relationship Of ◽  
The Relationship

In order to adapt to daily environmental changes, especially in relation to light availability, many organisms, such as plants, developed a vital mechanism that controls time-dependent biological events: the circadian clock. The circadian clock is responsible for predicting the changes that occur in the period of approximately 24 hours, preparing the plants for the following phases of the cycle. Some of these adaptations can influence the response of weeds to the herbicide application. Thus, the objectives of this review are to describe the physiological and genetic mechanisms of the circadian clock in plants, as well as to demonstrate the relationship of this phenomenon with the effectiveness of herbicides for weed control. Relationships are described between the circadian clock and the time of application of herbicides, leaf angle and herbicide interception, as well as photosynthetic activity in response to the circadian clock and herbicide efficiency. Further, it is discussed the role of phytochrome B (phyB) in the sensitivity of plants to glyphosate herbicide. The greater understanding of the circadian clock in plants is essential to achieve greater efficiency of herbicides and hence greater control of weeds and higher crop yields.

scholarly journals Temporal Regulation of Cytokines by the Circadian Clock

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Atsuhito Nakao
Keyword(s):  
Immune System ◽  
Immune Responses ◽  
Circadian Clock ◽  
Molecular Mechanisms ◽  
Host Immune System ◽  
Temporal Regulation ◽  
Cytokine Induction ◽  
Clock Proteins ◽  
New Strategies

Several parameters of the immune system exhibit oscillations with a period of approximately 24 hours that refers to “circadian rhythms.” Such daily variations in host immune system status might evolve to maximize immune reactions at times when encounters with pathogens are most likely to occur. However, the mechanisms behind circadian immunity have not been fully understood. Recent studies reveal that the internal time keeping system “circadian clock” plays a key role in driving the daily rhythms evident in the immune system. Importantly, several studies unveil molecular mechanisms of how certain clock proteins (e.g., BMAL1 and CLOCK) temporally regulate expression of cytokines. Since cytokines are crucial mediators for shaping immune responses, this review mainly summarizes the new knowledge that highlights an emerging role of the circadian clock as a novel regulator of cytokines. A greater understanding of circadian regulation of cytokines will be important to exploit new strategies to protect host against infection by efficient cytokine induction or to treat autoimmunity and allergy by ameliorating excessive activity of cytokines.

scholarly journals The Arabidopsis Circadian Clock and Metabolic Energy: A Question of Time

2021 ◽  
Vol 12 ◽  
Author(s):  
Luis Cervela-Cardona ◽  
Benjamin Alary ◽  
Paloma Mas
Keyword(s):  
Circadian Clock ◽  
Molecular Mechanisms ◽  
Environmental Changes ◽  
Building Blocks ◽  
Fundamental Principle ◽  
Metabolic Energy ◽  
Mitochondrial Activity ◽  
Cellular Processes ◽  
Control Growth ◽  
External Time

A fundamental principle shared by all organisms is the metabolic conversion of nutrients into energy for cellular processes and structural building blocks. A highly precise spatiotemporal programming is required to couple metabolic capacity with energy allocation. Cellular metabolism is also able to adapt to the external time, and the mechanisms governing such an adaptation rely on the circadian clock. Virtually all photosensitive organisms have evolved a self-sustained timekeeping mechanism or circadian clock that anticipates and responds to the 24-h environmental changes that occur during the day and night cycle. This endogenous timing mechanism works in resonance with the environment to control growth, development, responses to stress, and also metabolism. Here, we briefly describe the prevalent role for the circadian clock controlling the timing of mitochondrial activity and cellular energy in Arabidopsis thaliana. Evidence that metabolic signals can in turn feedback to the clock place the spotlight onto the molecular mechanisms and components linking the circadian function with metabolic homeostasis and energy.

scholarly journals Nonlinear phenomena in models of the circadian clock

2020 ◽  
Vol 17 (170) ◽  
pp. 20200556
Author(s):  
Inge van Soest ◽  
Marta del Olmo ◽  
Christoph Schmal ◽  
Hanspeter Herzel
Keyword(s):  
Circadian Clock ◽  
Molecular Mechanisms ◽  
Clock Genes ◽  
Period Doubling ◽  
Tissue Level ◽  
Cellular Level ◽  
Nonlinear Phenomena ◽  
Degradation Rates ◽  
Emergence Of Chaos

The mammalian circadian clock is well-known to be important for our sleep–wake cycles, as well as other daily rhythms such as temperature regulation, hormone release or feeding–fasting cycles. Under normal conditions, these daily cyclic events follow 24 h limit cycle oscillations, but under some circumstances, more complex nonlinear phenomena, such as the emergence of chaos, or the splitting of physiological dynamics into oscillations with two different periods, can be observed. These nonlinear events have been described at the organismic and tissue level, but whether they occur at the cellular level is still unknown. Our results show that period-doubling, chaos and splitting appear in different models of the mammalian circadian clock with interlocked feedback loops and in the absence of external forcing. We find that changes in the degradation of clock genes and proteins greatly alter the dynamics of the system and can induce complex nonlinear events. Our findings highlight the role of degradation rates in determining the oscillatory behaviour of clock components, and can contribute to the understanding of molecular mechanisms of circadian dysregulation.

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