A unique low light adaptation mechanism inRhodobacter azotoformans

Abstract Background: Liriope muscari (Decne.) L.H. Bailey is a valuable horticultural and medicinal plant that grows under a range of light intensities, from high to low, in the understories of shrubs. To understand how this species adapts to these various environments, we selected two groups of lilyturf growing under poplar trees at two different spacings. Each group was divided into three types, open field, forest edge and shaded forest with high, medium and low irradiance levels, respectively, and then we examined their photosynthetic characteristics, physiology and biomasses. Results: Light saturation point, light compensation point and in situ net photosynthetic rate ( P N ) were highest in lilyturf growing under high light. In contrast, lilyturf growing under low light had a higher apparent quantum yield and Chl a and b contents, indicating that they adapted to low light. Although the leaves of lilyturf growing under low light were small, their root tubers were heavier. Conclusions: The research demonstrates the eco-physiological basis of lilyturf’s shade adaptation mechanism as indicated by photosynthetic activity, chlorophyll fluorescence, Chl a, Chl b and Car contents when grown under different irradiances. We believe that lilyturf is a shade-tolerant plant suitable for planting in undergrowth, but attention should be paid to the canopy density of the forest when interplanting. The findings presented here advance our understanding of the photosynthetic characteristics of understory plants and may assist in the optimization of irradiances in the future.

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Light and dark adaptation in Phycomyces phototropism.

The Journal of General Physiology ◽

10.1085/jgp.84.1.101 ◽

1984 ◽

Vol 84 (1) ◽

pp. 101-118 ◽

Cited By ~ 36

Author(s):

P Galland ◽

V E Russo

Keyword(s):

Dark Adaptation ◽

Time Course ◽

Growth Response ◽

Light Adaptation ◽

Abnormal Behavior ◽

Adaptation Level ◽

Intensity Level ◽

Wild Type ◽

Adaptation Mechanism ◽

Intensity Range

Light and dark adaptation of the phototropism of Phycomyces sporangiophores were analyzed in the intensity range of 10(-7)-6 W X m-2. The experiments were designed to test the validity of the Delbrück-Reichardt model of adaptation (Delbrück, M., and W. Reichardt, 1956, Cellular Mechanisms in Differentiation and Growth, 3-44), and the kinetics were measured by the phototropic delay method. We found that their model describes adequately only changes of the adaptation level after small, relatively short intensity changes. For dark adaptation, we found a biphasic decay with two time constants of b1 = 1-2 min and b2 = 6.5-10 min. The model fails for light adaptation, in which the level of adaptation can overshoot the actual intensity level before it relaxes to the new intensity. The light adaptation kinetics depend critically on the height of the applied pulse as well as the intensity range. Both these features are incompatible with the Delbrück-Reichardt model and indicate that light and dark adaptation are regulated by different mechanisms. The comparison of the dark adaptation kinetics with the time course of the dark growth response shows that Phycomyces has two adaptation mechanisms: an input adaptation, which operates for the range adjustment, and an output adaptation, which directly modulates the growth response. The analysis of four different types of behavioral mutants permitted a partial genetic dissection of the adaptation mechanism. The hypertropic strain L82 and mutants with defects in the madA gene have qualitatively the same adaptation behavior as the wild type; however, the adaptation constants are altered in these strains. Mutation of the madB gene leads to loss of the fast component of the dark adaptation kinetics and to overshooting of the light adaptation under conditions where the wild type does not overshoot. Another mutant with a defect in the madC gene shows abnormal behavior after steps up in light intensity. Since the madB and madC mutants have been associated with the receptor pigment, we infer that at least part of the adaptation process is mediated by the receptor pigment.

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Nutrient-dependent low-light adaptation in the dinoflagellate Gonyaulax polyedra

Marine Biology ◽

10.1007/bf00413917 ◽

1983 ◽

Vol 74 (2) ◽

pp. 141-150 ◽

Cited By ~ 31

Author(s):

B. B. Pr�zelin ◽

H. A. Matlick

Keyword(s):

Light Adaptation ◽

Low Light ◽

Gonyaulax Polyedra

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CMOS photodetector with built-in light adaptation mechanism

Microelectronics Journal ◽

10.1016/0026-2692(93)90122-u ◽

1993 ◽

Vol 24 (5) ◽

pp. 547-553 ◽

Cited By ~ 16

Author(s):

Vivian Ward ◽

Marek Syrzycki ◽

Glenn Chapman

Keyword(s):

Light Adaptation ◽

Adaptation Mechanism

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A Mathematical Model to Characterize the Role of Light Adaptation in Mammalian Circadian Clock

Frontiers in Molecular Biosciences ◽

10.3389/fmolb.2021.681696 ◽

2021 ◽

Vol 8 ◽

Author(s):

Yuzeng Shi ◽

Yu Liu ◽

Ling Yang ◽

Jie Yan

Keyword(s):

Mathematical Model ◽

Circadian Clock ◽

Light Adaptation ◽

Light Stimulus ◽

Circadian System ◽

Jet Lag ◽

Short Term ◽

Adaptation Mechanism ◽

Role Of Light

In response to a light stimulus, the mammalian circadian clock first dramatically increases the expression of Per1 mRNA, and then drops to a baseline even when light persists. This phenomenon is known as light adaptation, which has been experimentally proven to be related to the CRTC1-SIK1 pathway in suprachiasmatic nucleus (SCN). However, the role of this light adaptation in the circadian rhythm remains to be elucidated. To reveal the in-depth function of light adaptation and the underlying dynamics, we proposed a mathematical model for the CRTC1-SIK1 network and coupled it to a mammalian circadian model. The simulation result proved that the light adaptation is achieved by the self-inhibition of the CRTC1/CREB complex. Also, consistently with experimental observations, this adaptation mechanism can limit the phase response to short-term light stimulus, and it also restricts the rate of the phase shift in a jet lag protocol to avoid overly rapid re-entrainment. More importantly, this light adaptation is predicted to prevent the singularity behavior in the cell population, which represents the abolishment of circadian rhythmicity due to desynchronization of oscillating cells. Furthermore, it has been shown to provide refractoriness to successive stimuli with short gap. Therefore, we concluded that the light adaptation generated by the CRTC1-SIK1 pathway in the SCN provides a robust mechanism, allowing the circadian system to maintain homeostasis in the presence of light perturbations. These results not only give new insights into the dynamics of light adaptation from a computational perspective but also lead us to formulate hypotheses about the related physiological significance.

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Effect of Light Intensity on the Morpho-physiological Traits and Grain Yield of Finger Millet

Current Journal of Applied Science and Technology ◽

10.9734/cjast/2020/v39i2230849 ◽

2020 ◽

pp. 105-113

Author(s):

Y. A. Nanja Reddy ◽

K. T. Krishne Gowda

Keyword(s):

Light Intensity ◽

Grain Yield ◽

Finger Millet ◽

Light Adaptation ◽

Monsoon Season ◽

Low Light ◽

Potential Yield ◽

Low Light Intensity ◽

Early Maturing ◽

Net Assimilation

The normal light intensity during monsoon season in rainfed finger millet cultivation regions in particular, Bangalore, is around 1200 uMm-2s-1; the effect of reduction in light intensity on physiological parameters and grain yield of finger millet was studied. The experiment was laid out in split plot design with four light intensity treatments and three varieties in three replications. Each replication had four lines of 1.5 m row length (1.5 m x 1.0 m). The crop was directly sown on 03-08-2007 with the spacing of 22.5 cm between rows and 10 cm between the hills, using three varieties namely, GPU-48 (early maturing variety, 100 days), GPU-28 (medium maturing variety, 110 days), and L-5 (late maturing variety, 120 days). Decreased light intensity at canopy level decreased the leaf area, specific leaf weight, net assimilation rate and biomass production, which resulted in decreased grain yield in all varieties. Mean grain yield decreased by 16.4, 34.7 and 55.7% respectively with 75, 50 and 25% light intensity. Low light intensity decreased the biomass, which is important in regional fodder security. Early maturing variety had lesser percent reduction in grain yield (1.68%) as compared to the medium (9.5%) and late maturing (29.0%) varieties at low light intensity of 75 % natural light. Therefore, the critical lower limit of light intensity could be nearly 1200 uMm-2s-1 for finger millet potential yield. The results obtained in this study also suggests that genotypic variability for low light adaptation of early maturing genotype (GPU-48) can be exploited for intercropping systems in rainfed mango plantations up to 4-5 years.

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THE VISUAL FUNCTIONS OF THE COMPLETE COLORBLIND

The Journal of General Physiology ◽

10.1085/jgp.31.6.459 ◽

1948 ◽

Vol 31 (6) ◽

pp. 459-472 ◽

Cited By ~ 59

Author(s):

Selig Hecht ◽

Simon Shlaer ◽

Emil L. Smith ◽

Charles Haig ◽

James C. Peskin

Keyword(s):

Continuous Function ◽

Dark Adaptation ◽

Light Adaptation ◽

The Other ◽

Intensity Discrimination ◽

Sharp Transition ◽

Low Light ◽

Fusion Frequency ◽

Visual Functions ◽

Critical Fusion Frequency

1. The visual functions of a completely colorblind individual are compared with those of the normal. The sensibility distribution in the spectrum has a maximum at 520 mµ at all brightnesses and thus corresponds to rod vision alone. This is confirmed by studies of dark adaptation which show final thresholds like those usually found for rod vision. Dark adaptation, measured both centrally and peripherally in the retina, is a single continuous function, and regardless of the brightness of the preceding light adaptation, is of the rapid type only, such as that found for the normal following low light adaptation. Visual acuity also shows a single continuous function like that for rod vision. 2. Both critical fusion frequency and intensity discrimination show two sections, one at low and the other at high intensities with a sharp transition from one to the other. Intensity discrimination is as good as for the normal eye, and covers much the same range. The maximal critical fusion frequency is only about 20 cycles per second as compared to 55 cycles for the normal. 3. The two sections shown by the colorblind eye for intensity discrimination and fusion frequency possess the spectral sensitivity of rod vision since the relative positions on the intensity scale are not influenced by using different parts of the spectrum.

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Photosynthetic performance and growth responses of Liriope muscari (Decne.) L.H. Bailey (Asparagaceae) planted within poplar forests having different canopy densities

10.21203/rs.2.18505/v3 ◽

2020 ◽

Author(s):

jiaojiao zhang ◽

Ling Zhu ◽

Xu Zhang ◽

Jian Zhou

Keyword(s):

Forest Edge ◽

Photosynthetic Performance ◽

Photosynthetic Characteristics ◽

Growth Responses ◽

Apparent Quantum Yield ◽

Low Light ◽

Adaptation Mechanism ◽

Physiological Basis ◽

Chl A ◽

Point Light

Abstract Background: Liriope muscari (Decne.) L.H. Bailey is a valuable horticultural and medicinal plant that grows under a range of light intensities, from high to low, in the understories of shrubs. To understand how this species adapts to these various environments, we selected two groups of lilyturf growing under poplar trees at two different spacings. Each group was divided into three types, open field, forest edge and shaded forest with high, medium and low irradiance levels, respectively, and then we examined their photosynthetic characteristics, physiology and biomasses. Results: Light saturation point, light compensation point and in situ net photosynthetic rate (PN) were highest in lilyturf growing under high light. In contrast, lilyturf growing under low light had a higher apparent quantum yield and Chl a and b contents, indicating that they adapted to low light. Although the leaves of lilyturf growing under low light were small, their root tubers were heavier. Conclusions: The research demonstrates the eco-physiological basis of lilyturf’s shade adaptation mechanism as indicated by photosynthetic activity, chlorophyll fluorescence, Chl a, Chl b and Car contents when grown under different irradiances. We believe that lilyturf is a shade-tolerant plant suitable for planting in undergrowth, but attention should be paid to the canopy density of the forest when interplanting. The findings presented here advance our understanding of the photosynthetic characteristics of understory plants and may assist in the optimization of irradiances in the future.

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Effects of high light on transcripts of stress-associated genes for the cyanobacteria Synechocystis sp. PCC 6803 and Prochlorococcus MED4 and MIT9313

Microbiology ◽

10.1099/mic.0.27014-0 ◽

2004 ◽

Vol 150 (5) ◽

pp. 1271-1281 ◽

Cited By ~ 29

Author(s):

Isabelle Mary ◽

Chao-Jung Tu ◽

Arthur Grossman ◽

Daniel Vaulot

Keyword(s):

Light Adaptation ◽

Critical Role ◽

High Light ◽

Ecological Niches ◽

Transcript Accumulation ◽

Low Light ◽

Strain Characteristic ◽

Associated Proteins ◽

Kinetics Of ◽

Pcc 6803

Cyanobacteria constitute an ancient, diverse and ecologically important bacterial group. The responses of these organisms to light and nutrient conditions are finely controlled, enabling the cells to survive a range of environmental conditions. In particular, it is important to understand how cyanobacteria acclimate to the absorption of excess excitation energy and how stress-associated transcripts accumulate following transfer of cells from low- to high-intensity light. In this study, quantitative RT-PCR was used to monitor changes in levels of transcripts encoding chaperones and stress-associated proteases in three cyanobacterial strains that inhabit different ecological niches: the freshwater strain Synechocystis sp. PCC 6803, the marine high-light-adapted strain Prochlorococcus MED4 and the marine low-light-adapted strain Prochlorococcus MIT9313. Levels of transcripts encoding stress-associated proteins were very sensitive to changes in light intensity in all of these organisms, although there were significant differences in the degree and kinetics of transcript accumulation. A specific set of genes that seemed to be associated with high-light adaptation (groEL/groES, dnaK2, dnaJ3, clpB1 and clpP1) could be targeted for more detailed studies in the future. Furthermore, the strongest responses were observed in Prochlorococcus MED4, a strain characteristic of the open ocean surface layer, where hsp genes could play a critical role in cell survival.

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