Faculty Opinions recommendation of The circadian clock coordinates plant development through specificity at the tissue and cellular level.

It is postulated that the changes in growth and metabolic activity that characterize many features of plant development are produced by the interaction between the hydraulic conductivity of the tissues and the influence of environmental factors, transpiration and osmotic gradients on the uptake, distribution, or loss of water. Mechanisms based on this concept are proposed for six aspects of development. These are (i) seed germination and stem elongation (water uptake), (ii) apical dominance and tropisms (water distribution), and (iii) leaf senescence and abscission (water loss). The postulated mechanisms are based on the hypothesis that water is the factor that normally limits the rate of growth and metabolic activity in the intact plant. The validity of the concept is supported by the unique capacity of water to perform three basic functions. These functions are (i) to mediate environmental effects on growth and metabolism, (ii) to correlate the growth of different parts of the plant, and (iii) to integrate growth and metabolic activity at the cellular level. It is also suggested that the responses induced by the application to plants of certain growth-regulating substances can be mainly attributed to the capacity of these substances to promote the uptake of water.

Download Full-text

Mechanism of Heat Stress and their Management Strategies in Wheat

Indian Journal of Pure & Applied Biosciences ◽

10.18782/2582-2845.8741 ◽

2021 ◽

Vol 9 (4) ◽

pp. 8-30

Author(s):

Ali Ammar ◽

Keyword(s):

Quantitative Trait Locus ◽

Heat Stress ◽

Plant Development ◽

Management Strategies ◽

Wheat Yield ◽

Cellular Level ◽

Seedling Development ◽

Cell Water ◽

Wheat Growth ◽

Trait Locus

Cumulative heat with resulting alterations to weather unfavorably disturb plant development, resultant in disastrous damage in wheat output. With one degree increase in temperature, wheat growth is projected to decrease by 6%. Comprehensive summary of morpho-physiological replies to wheat for temperature pressure might assist expressing suitable approaches in temperature pressure wheat yield development. Moreover, penetrating to conceivable managing approaches might elevate output and sustainability of rising wheat. Main conclusions after this review is follows: (1) temperature pressure meaningfully decreases kernel sprouting and seedling development, turgidness of the cell, water use competence of the plant; (2) During cellular level, temperature pressure interrupts cellular purposes over making unnecessary sensitive oxygen types, foremost towards oxidative pressure; (3) main replies to wheat for temperature pressure comprise improvement to senescence of leaf, decrease in photosynthesis, defusing of enzymes of photosynthesis, production of oxidative losses to chloroplasts; (4) temperature pressure too decreases number of grains and size via upsetting ounce setting, translocation of integrates and period and development proportion of grains; (5) actual methods to manage temperature pressure in wheat comprise screening accessible germplasm beneath field hearings and/or retaining marker aided assortment, claim to external protectants for seeds or plants, mapping quantitative trait locus discussing temperature confrontation and breeding; (6) Well combined genetic and agronomical organization choice might improve wheat acceptance for temperature. Though, achievement to apply numerous methods for temperature pressure organization needs better understanding of temperature acceptance topographies, molecular cloning, and description of genes. General achievement to multifaceted plant temperature pressure administration depends on intensive exertions to crop modelers, molecular biologists, and plant physiologists.

Download Full-text

The effects of altering extracellular potassium ion concentration on the membrane potential and circadian clock of Paramecium bursaria.

Journal of Experimental Biology ◽

10.1242/jeb.197.1.295 ◽

1994 ◽

Vol 197 (1) ◽

pp. 295-308

Author(s):

C H Johnson ◽

Y Nakaoka ◽

I Miwa

Keyword(s):

Membrane Potential ◽

Circadian Clock ◽

Biological Clock ◽

Cellular Level ◽

Ion Concentration ◽

Extracellular Potassium ◽

Extracellular Potassium Concentration ◽

Transmembrane Flux ◽

Circadian Organization ◽

The Impact

In some neural models of circadian rhythmicity, membrane potential and transmembrane flux of potassium and calcium ions appear to play important roles in the entrainment and central mechanisms of the biological clock. We wondered whether these cellular variables might be generally involved in circadian clocks, even non-neural clocks. Therefore, we tested the impact of changing extracellular potassium level on the circadian rhythm of photoaccumulation of Paramecium cells, whose membrane potential responds to changes of extracellular potassium in a manner similar to that of neurones. We found that pulse or step changes of extracellular potassium concentration did not phase-shift the circadian clock of P. bursaria cells in a phase-specific manner. Furthermore, modifying the extracellular concentration of calcium did not affect the magnitude of light-induced phase resetting. Therefore, while membrane potential and calcium fluxes may be crucial components of the circadian clock system in some organisms, especially in neural systems that involve intercellular communication, the P. bursaria data indicate that membrane potential changes are not necessarily an intrinsic component of circadian organization at the cellular level.

Download Full-text

Out of breath, out of time: interactions between HIF and circadian rhythms

AJP Cell Physiology ◽

10.1152/ajpcell.00305.2020 ◽

2020 ◽

Vol 319 (3) ◽

pp. C533-C540

Author(s):

Emma J. O’Connell ◽

Chloe-Anne Martinez ◽

Yichuan G. Liang ◽

Peter A. Cistulli ◽

Kristina M. Cook

Keyword(s):

Circadian Clock ◽

Feedback Loop ◽

Molecular Mechanisms ◽

Hypoxia Inducible Factor ◽

Cellular Level ◽

The Body ◽

Circadian Clocks ◽

Molecular Clocks ◽

Circadian Transcription ◽

New Strategies

Humans have internal circadian clocks that ensure that important physiological functions occur at specific times of the day. These molecular clocks are regulated at the genomic level and exist in most cells of the body. Multiple circadian resetting cues have been identified, including light, temperature, and food. Recently, oxygen has been identified as a resetting cue, and emerging science indicates that this occurs through interactions at the cellular level between the circadian transcription-translation feedback loop and the hypoxia-inducible pathway (hypoxia-inducible factor; subject of the 2019 Nobel Prize in Physiology or Medicine). This review will cover recently identified relationships between HIF and proteins of the circadian clock. Interactions between the circadian clock and hypoxia could have wide-reaching implications for human diseases, and understanding the molecular mechanisms regulating these overlapping pathways may open up new strategies for drug discovery.

Download Full-text

Nonlinear phenomena in models of the circadian clock

Journal of The Royal Society Interface ◽

10.1098/rsif.2020.0556 ◽

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.

Download Full-text

Correction to: Circadian clock during plant development

Journal of Plant Research ◽

10.1007/s10265-018-1015-z ◽

2018 ◽

Vol 131 (3) ◽

pp. 571-571

Author(s):

Keisuke Inoue ◽

Takashi Araki ◽

Motomu Endo

Keyword(s):

Circadian Clock ◽

Plant Development

Download Full-text

Interaction of light and gravity signals as a mechanism of counteracting alterations caused by simulated microgravity in proliferating plant cells

10.21203/rs.3.rs-29236/v1 ◽

2020 ◽

Author(s):

Aránzazu Manzano ◽

Veronica Pereda-Loth ◽

Anne de Bures ◽

Julio Sáez-Vásquez ◽

Raúl Herranz ◽

...

Keyword(s):

Plant Development ◽

Ribosome Biogenesis ◽

Simulated Microgravity ◽

Life Support ◽

Cellular Level ◽

Differential Sensitivity ◽

Molecular Alterations ◽

Gravitational Stress ◽

To Come ◽

Spaceflight Experiments

Abstract Background Light and gravity are fundamental cues for plant development on Earth. In space, understanding the effects of changing conditions affecting to these two stimuli is key for optimizing the life support systems to come with space exploration. Simulated microgravity is useful as a complement to real spaceflight experiments into refining our knowledge of early plant development adaptation to extraterrestrial environments. Results In wild type Arabidopsis and in mutants of the two genes of the essential nucleolar protein nucleolin (nuc1 and nuc2), the use of an extended toolbox of cell proliferation, cell growth and ribosome biogenesis markers, has allowed us to show that the incorporation of an illumination regime, in this case photoperiod, has been sufficient to attenuate or suppress the effects caused by gravitational stress at the cellular level in the root meristem. These results are consistent with other experiments carried out at real and simulated microgravity in which early plant development is nominal when the environmental conditions are optimal (nutrients, light, temperature, humidity). Conclusions Light signals may total or partially replace gravity signals significantly improving plant growth and development in microgravity. Despite that, molecular alterations are still compatible with the expected adaptation mechanisms that should be better understood. The differential sensitivity of nuc1 and nuc2 mutants to gravitational stress points to new strategies to produce more resilient plants to travel with humans in new extraterrestrial endeavors.

Download Full-text