Synchronizing the Neurospora crassa circadian clock with the rhythmic environment

2005 ◽  
Vol 33 (5) ◽  
pp. 949-952 ◽  
Author(s):  
N. Price-Lloyd ◽  
M. Elvin ◽  
C. Heintzen
Keyword(s):  
Light Intensity ◽  
Circadian Clock ◽  
Neurospora Crassa ◽  
Model Organism ◽  
Circadian Clocks ◽  
Current Understanding ◽  
Signalling Pathways ◽  
Selection Pressures ◽  
The Earth ◽  
Natural Cycles

The metronomic predictability of the environment has elicited strong selection pressures for the evolution of endogenous circadian clocks. Circadian clocks drive molecular and behavioural rhythms that approximate the 24 h periodicity of our environment. Found almost ubiquitously among phyla, circadian clocks allow preadaptation to rhythms concomitant with the natural cycles of the Earth. Cycles in light intensity and temperature for example act as important cues that couple circadian clocks to the environment via a process called entrainment. This review summarizes our current understanding of the general and molecular principles of entrainment in the model organism Neurospora crassa, a simple eukaryote that has one of the best-studied circadian systems and light-signalling pathways.

scholarly journals Mechanisms Underlying the Complex Dynamics of Temperature Entrainment by a Circadian Clock

2021 ◽  
Author(s):  
Philipp Burt ◽  
Saskia Grabe ◽  
Cornelia Madeti ◽  
Abhishek Upadhyay ◽  
Martha Merrow ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Circadian Clock ◽  
Neurospora Crassa ◽  
Seasonal Variations ◽  
Complex Dynamics ◽  
Model Organism ◽  
Period Doubling ◽  
Circadian Clocks ◽  
Nonlinear Phenomena ◽  
Temperature Rhythms

AbstractAutonomously oscillating circadian clocks resonate with daily environmental (zeitgeber) rhythms to organize physiology around the solar day. While entrainment properties and mechanisms have been studied widely and in great detail for light-dark cycles, entrainment to daily temperature rhythms remains poorly understood despite that they are potent zeitgebers.Here we investigate the entrainment of the chronobiological model organism Neurospora crassa, subject to thermocycles of different periods and fractions of warm versus cold phases, mimicking seasonal variations. Depending on the properties of these thermocycles, regularly entrained rhythms, period-doubling (frequency demultiplication) but also irregular aperiodic behavior occurs. We demonstrate that the complex nonlinear phenomena of experimentally observed entrainment dynamics can be understood by molecular mathematical modeling.Abstract Figure

scholarly journals Cellular signalling and the complexity of biological timing: insights from the ultradian clock of Schizosaccharomyces pombe

2001 ◽  
Vol 356 (1415) ◽  
pp. 1725-1733 ◽  
Author(s):  
Fred Kippert
Keyword(s):  
Protein Kinase ◽  
Schizosaccharomyces Pombe ◽  
Model Organism ◽  
Circadian Clocks ◽  
Mitogen Activated Protein Kinase ◽  
Signalling Pathways ◽  
Cellular Signalling ◽  
Short Period ◽  
Mitogen Activated Protein ◽  
Cellular Signalling Pathways

The molecular bases of circadian clocks are complex and cannot be sufficiently explained by the relatively simple feedback loops, based on transcription and translation, of current models. The existence of additional oscillators has been demonstrated experimentally, but their mechanism(s) have so far resisted elucidation and any universally conserved clock components have yet to be identified. The fission yeast, Schizosaccharomyces pombe , as a simple and well–characterized eukaryote, is a useful model organism in the investigation of many aspects of cell regulation. In fast–growing cells of the yeast an ultradian clock operates, which can serve as a model system to analyse clock complexity. This clock shares strict period homeostasis and efficient entrainment with circadian clocks but, because of its short period of 30 min, mechanisms other than a transcription/translation–based feedback loop must be working. An initial systematic screen involving over 200 deletion mutants has shown that major cellular signalling pathways (calcium/phosphoinositide, mitogen–activated protein kinase and cAMP/protein kinase A) are crucial for the normal functioning of this ultradian clock. A comparative examination of the role of cellular signalling pathways in the S.pombe ultradian clock and in the circadian timekeeping of different eukaryotes may indicate common principles in biological timing processes that are universally conserved amongst eukaryotes.

scholarly journals The Resonance and Adaptation of Neurospora crassa Circadian and Conidiation Rhyth ms to Short Light-Dark Cycles

2021 ◽  
Vol 8 (1) ◽  
pp. 27
Author(s):  
Huan Ma ◽  
Luyao Li ◽  
Jie Yan ◽  
Yin Zhang ◽  
Xiaohong Ma ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Neurospora Crassa ◽  
Circadian Clocks ◽  
Extreme Conditions ◽  
Behavioral Rhythms ◽  
The Core ◽  
Regulatory Aspects ◽  
Ubiquitin E3 Ligase ◽  
Modeling And Experiments ◽  
Clock Protein

Circadian clocks control the physiological and behavioral rhythms to adapt to the environment with a period of ~24 h. However, the influences and mechanisms of the extreme light/dark cycles on the circadian clock remain unclear. We showed that, in Neurospora crassa, both the growth and the microconidia production contribute to adaptation in LD12:12 (12 h light/12 h dark, periodically). Mathematical modeling and experiments demonstrate that in short LD cycles, the expression of the core clock protein FREQUENCY was entrained to the LD cycles when LD > 3:3 while it free ran when T ≤ LD3:3. The conidial rhythmicity can resonate with a series of different LD conditions. Moreover, we demonstrate that the existence of unknown blue light photoreceptor(s) and the circadian clock might promote the conidiation rhythms that resonate with the environment. The ubiquitin E3 ligase FWD-1 and the previously described CRY-dependent oscillator system were implicated in regulating conidiation under short LD conditions. These findings shed new light on the resonance of Neurospora circadian clock and conidiation rhythms to short LD cycles, which may benefit the understandings of both the basic regulatory aspects of circadian clock and the adaptation of physiological rhythms to the extreme conditions.

scholarly journals How to Live on Mars With a Proper Circadian Clock?

2022 ◽  
Vol 8 ◽  
Author(s):  
Rujia Luo ◽  
Yutao Huang ◽  
Huan Ma ◽  
Jinhu Guo
Keyword(s):  
Circadian Rhythms ◽  
Circadian Clock ◽  
The Self ◽  
Circadian Clocks ◽  
Environmental Cues ◽  
Circadian Misalignment ◽  
The Earth ◽  
Adaptive Challenges ◽  
Rotation Of The Earth ◽  
And Behavior

Intrinsic circadian clocks generate circadian rhythms of physiology and behavior, which provide the capabilities to adapt to cycling environmental cues that result from the self-rotation of the Earth. Circadian misalignment leads to deleterious impacts on adaptation and health in different organisms. The environmental cues on the interplanetary journey to and on Mars dramatically differ from those on Earth. These differences impose numerous adaptive challenges, including challenges for humans’ circadian clock. Thus, adaptation of circadian rhythms to the Martian environment is a prerequisite for future landing and dwelling on Mars. Here, we review the progress of studies associated with the influence of the Martian environment on circadian rhythms and propose directions for further study and potential strategies to improve the adaptation of the circadian clock for future Mars missions.

scholarly journals RNAseq shows an all-pervasive day-night rhythm in the transcriptome of the pacemaker of the heart

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yanwen Wang ◽  
Cali Anderson ◽  
Halina Dobrzynski ◽  
George Hart ◽  
Alicia D’Souza ◽  
...  
Keyword(s):  
Heart Rate ◽  
Nervous System ◽  
Circadian Clock ◽  
Sick Sinus Syndrome ◽  
Sinus Node ◽  
Signalling Pathways ◽  
Resting Heart Rate ◽  
Ion Channel Regulation ◽  
Channel Regulation ◽  
Physiological Systems

AbstractPhysiological systems vary in a day-night manner anticipating increased demand at a particular time. Heart is no exception. Cardiac output is primarily determined by heart rate and unsurprisingly this varies in a day-night manner and is higher during the day in the human (anticipating increased day-time demand). Although this is attributed to a day-night rhythm in post-translational ion channel regulation in the heart’s pacemaker, the sinus node, by the autonomic nervous system, we investigated whether there is a day-night rhythm in transcription. RNAseq revealed that ~ 44% of the sinus node transcriptome (7134 of 16,387 transcripts) has a significant day-night rhythm. The data revealed the oscillating components of an intrinsic circadian clock. Presumably this clock (or perhaps the master circadian clock in the suprachiasmatic nucleus) is responsible for the rhythm observed in the transcriptional machinery, which in turn is responsible for the rhythm observed in the transcriptome. For example, there is a rhythm in transcripts responsible for the two principal pacemaker mechanisms (membrane and Ca2+ clocks), transcripts responsible for receptors and signalling pathways known to control pacemaking, transcripts from genes identified by GWAS as determinants of resting heart rate, and transcripts from genes responsible for familial and acquired sick sinus syndrome.

scholarly journals COMPLEMENTATION ANALYSIS OF LINKED CIRCADIAN CLOCK MUTANTS OF NEUROSPORA CRASSA

Genetics ◽  
1976 ◽  
Vol 82 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Jerry F Feldman ◽  
Marian N Hoyle
Keyword(s):  
Linkage Group ◽  
Circadian Clock ◽  
Neurospora Crassa ◽  
Period Length ◽  
Complementation Analysis ◽  
Wild Type ◽  
The Right

ABSTRACT A fourth mutant of Neurospora crassa, designated frq-4, has been isolated in which the period length of the circadian conidiation rhythm is shortened to 19.3 ± 0.3 hours. This mutant is tightly linked to the three previously isolated frq mutants, and all four map to the right arm of linkage group VII about 10 map units from the centromere. Complementation tests suggest, but do not prove, that all four mutations are allelic, since each of the four mutants is co-dominant with the frq  + allele—i.e., heterokaryons have period lengths intermediate between the mutant and wild-type—and since heterokaryons between pairs of mutants also have period lengths intermediate between those of the two mutants.

scholarly journals Epistatic and Synergistic Interactions Between Circadian Clock Mutations in Neurospora crassa

Genetics ◽  
2001 ◽  
Vol 159 (2) ◽  
pp. 537-543
Author(s):  
Louis W Morgan ◽  
Jerry F Feldman
Keyword(s):  
Circadian Clock ◽  
Neurospora Crassa ◽  
Mutant Strain ◽  
Temperature Compensation ◽  
Double Mutant ◽  
Synergistic Interactions ◽  
Long Period ◽  
Double Mutant Strain ◽  
Short Period ◽  
Compensation Mechanisms

Abstract We identified a series of epistatic and synergistic interactions among the circadian clock mutations of Neurospora crassa that indicate possible physical interactions among the various clock components encoded by these genes. The period-6 (prd-6) mutation, a short-period temperature-sensitive clock mutation, is epistatic to both the prd-2 and prd-3 mutations. The prd-2 and prd-3 long-period mutations show a synergistic interaction in that the period length of the double mutant strain is considerably longer than predicted. In addition, the prd-2 prd-3 double mutant strain also exhibits overcompensation to changes in ambient temperature, suggesting a role in the temperature compensation machinery of the clock. The prd-2, prd-3, and prd-6 mutations also show significant interactions with the frq7 long-period mutation. These results suggest that the gene products of prd-2, prd-3, and prd-6 play an important role in both the timing and temperature compensation mechanisms of the circadian clock and may interact with the FRQ protein.

scholarly journals A Functional Connection between the Circadian Clock and Hormonal Timing in Arabidopsis

Genes ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 567 ◽  
Author(s):  
Manjul Singh ◽  
Paloma Mas
Keyword(s):  
Circadian Clock ◽  
Biological Significance ◽  
Feedback Regulation ◽  
Environmental Cues ◽  
Hormone Signaling ◽  
Functional Connection ◽  
The Earth ◽  
Exogenous Cues ◽  
Rotation Of The Earth ◽  
Molecular Components

The rotation of the Earth entails changes in environmental conditions that pervasively influence an organism’s physiology and metabolism. An internal cellular mechanism known as the circadian clock acts as an internal timekeeper that is able to perceive the changes in environmental cues to generate 24-h rhythms in synchronization with daily and seasonal fluctuations. In plants, the circadian clock function is particularly important and regulates nearly every aspect of plant growth and development as well as proper responses to stresses. The circadian clock does not function in isolation but rather interconnects with an intricate network of different pathways, including those of phytohormones. Here, we describe the interplay of the circadian clock with a subset of hormones in Arabidopsis. The molecular components directly connecting the circadian and hormone pathways are described, highlighting the biological significance of such connections in the control of growth, development, fitness, and survival. We focus on the overlapping as well as contrasting circadian and hormonal functions that together provide a glimpse on how the Arabidopsis circadian system regulates hormone function in response to endogenous and exogenous cues. Examples of feedback regulation from hormone signaling to the clock are also discussed.

scholarly journals 1.3.5 On the Visibility of the Libration Clouds

1976 ◽  
Vol 31 ◽  
pp. 124-129
Author(s):  
S. Röser
Keyword(s):  
Light Intensity ◽  
Satellite Observations ◽  
Libration Points ◽  
Angular Diameter ◽  
Schmidt Telescope ◽  
Zodiacal Light ◽  
Average Brightness ◽  
Upper Limit ◽  
The Earth

In recent years satellite observations of the region of the Earth-Moon libration points L4 and L5 became available, which showed different results. Roach (1975) has measured perturbations of the Zodiacal Light intensity near the libration points L4 and L5 with a photometer on board the OSO-6 satellite. He interpreted the results as counterglow of a cloud of particles, having an angular diameter of 6 degrees and an average brightness of 20 S10v, whereas observations by Burnett et al. (1974) set an upper limit of 10 S10 blue. Earth bound observations made by Bruman (1969) with the 48-inch Palomar Schmidt telescope gave no indication for discrete objects nor for clouds.

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