Floral initiation in Lolium temulentum L.: the role of phytochrome in the responses to red and far-red light

Planta ◽  
1971 ◽  
Vol 98 (3) ◽  
pp. 232-243 ◽  
Author(s):  
R. W. K. Holland ◽  
Daphne Vince
Keyword(s):  
Red Light ◽  
Floral Initiation ◽  
Lolium Temulentum

scholarly journals Examining the role of red background in magnocellular contribution to face perception

2015 ◽  
Author(s):  
Bhuvanesh Awasthi ◽  
Mark A Williams ◽  
Jason Friedman
Keyword(s):  
Spatial Frequency ◽  
Face Perception ◽  
Red Light ◽  
Specific Property ◽  
High Spatial Frequency ◽  
Arm Movement ◽  
Frequency Component ◽  
Behavioral Evidence ◽  
Movement Curvature

This study examines the role of the magnocellular system in the early stages of face perception, in particular sex categorization. Utilizing the specific property of magnocellular suppression in red light, we investigated visually guided reaching to low and high spatial frequency hybrid faces against red and grey backgrounds. The arm movement curvature measure shows that reduced response of the magnocellular pathway interferes with the low spatial frequency component of face perception. This is the first definitive behavioral evidence for magnocellular contribution to face perception.

scholarly journals The Role of Various Regions of the Bean Hypocotyl on Red Light-induced Hook Opening

1971 ◽  
Vol 48 (2) ◽  
pp. 183-186 ◽  
Author(s):  
Bernard Rubinstein
Keyword(s):  
Red Light ◽  
Bean Hypocotyl

Role of red light in hair-whorl formation induced by blue light in Acetabularia mediterranea

Planta ◽  
1990 ◽  
Vol 181 (1) ◽  
Author(s):  
Rainer Schmid ◽  
Martin T�nnermann ◽  
Evi-Marion Idziak
Keyword(s):  
Blue Light ◽  
Red Light ◽  
Acetabularia Mediterranea

Drivers' Perceptions of Unsafe Driving Behaviors and Their Countermeasures: A Study in Saudi Arabia

2014 ◽  
Vol 70 (4) ◽  
Author(s):  
Tanweer Hasan ◽  
Ishtiaque Ahmed ◽  
Hamid O. Al-Bar
Keyword(s):  
Saudi Arabia ◽  
Police Officers ◽  
Time Pressure ◽  
Red Light ◽  
The United States ◽  
Aggressive Driving ◽  
Road Rage ◽  
Driving Behaviors ◽  
Wide Range

There is an increased public concern about the role of aggressive driving and "road rage" in crashes and traffic fatalities. There is no general agreement as to what constitutes aggressive driving. Consequently, the objective of the study was to survey of the perceptions on the specific unsafe driving acts. Perceptions and beliefs of drivers about unsafe and aggressive driving actions and their countermeasures are presented in this paper. The study primarily looked at the wide range of driver attitudes about speeding and other forms of unsafe driving behavior. The study was conducted in Jeddah, the second largest city of Saudi Arabia by interviewing a sample of 300 drivers. The results indicated that the drivers, in general, prefer to drive at higher speeds and could be considered as more aggressive compared to the drivers in the United States. The most dangerous reported driving act was "drive thru red light", followed by "racing another driver". Only 23% of the drivers thought that it was dangerous to drive over 30 km of the legal speed limits. The most often seen unsafe driving action was "speeding (70%), followed by "driving too closely (57%), "failing to use turn signals (53%), "drive inattentively (50%)", and "running red lights (43%)". The main causes of unsafe driving behaviors were "being in a hurry/time pressure (66%)", "aggressive behavior of others (52%)", and "refusing traffic rules (51%)". The countermeasure that was viewed to be the most effective in reducing unsafe driving behaviors was assigning more traffic police officers (66%). The study revealed that, more than half the drivers believed that more frequent ticketing (60%), doubling or tripling fines (54%), and doubling the length of imprisonment (53%) would be effective in reducing unsafe driving behaviors.

The Promoting Effect of Far-Red Light on Flowering in the Long Day Plant Lolium temulentum

1965 ◽  
Vol 18 (2) ◽  
pp. 474-482 ◽  
Author(s):  
Daphne Vince
Keyword(s):  
Red Light ◽  
Promoting Effect ◽  
Lolium Temulentum ◽  
Long Day

Asymmetric cell division and differentiation; fern spore germination as a model. II. Ultrastructural studies

1985 ◽  
Vol 86 ◽  
pp. 227-230
Author(s):  
Alix R. Bassel
Keyword(s):  
Cell Division ◽  
Metal Binding ◽  
Asymmetric Cell Division ◽  
Red Light ◽  
Nuclear Migration ◽  
Silver Stain ◽  
Metal Binding Sites ◽  
Ultrastructural Studies ◽  
Fern Spore Germination

SynopsisThe germination of Onoclea spores is a model system with many advantages for the study of asymmetric cell division and cellular differentiation. Our results suggest that both microtubules and a lipophilic site are important in the nuclear migration to one end of the spore prior to asymmetric cell division. A metalbinding region containing pore-like structures in the proximal face of the spore coat may be a source of the inherent polarity of the spore. The pattern of endogenous metal binding during germination has been characterised using a sulphide-silver stain. Metal-binding sites are described in a differentiating system in which polarity is imposed externally using polarised red light. The possibility of a role of ion gradients in determining the direction of nuclear migration is discussed.

scholarly journals Gibberellins and flowering in long day plants, with special reference to Lolium temulentum

1999 ◽  
Vol 26 (1) ◽  
pp. 1 ◽  
Author(s):  
L. T. Evans
Keyword(s):  
Environmental Control ◽  
Control Points ◽  
Subsequent Work ◽  
Feedback Effects ◽  
Factors Affecting ◽  
Lolium Temulentum ◽  
Long Day ◽  
Precise Role ◽  
Flowering Process

The relation between gibberellins (GAs) and flowering in some long day (LD) plants is reviewed, with particular emphasis on Lolium temulentum. Lang’s early experiments with rosette plants established the effectiveness of several GAs in replacing the need for LD. Subsequent work with mutants, especially of Arabidopsis, has clarified genetic and environmental control points in GA synthesis, various feedback effects and some of the factors affecting responsiveness to, as well as synthesis of, GAs in the flowering process. Further complexities are revealed in the experiments with Lolium temulentum, which have clearly shown that the structural requirements for effectiveness of GAs in the flowering process are quite different from those for elongation growth. The precise role of GAs in the long day induction of flowering remains unclear.

scholarly journals On the (un)coupling of the chromophore, tongue interactions, and overall conformation in a bacterial phytochrome

2018 ◽  
Vol 293 (21) ◽  
pp. 8161-8172 ◽  
Author(s):  
Heikki Takala ◽  
Heli K. Lehtivuori ◽  
Oskar Berntsson ◽  
Ashley Hughes ◽  
Rahul Nanekar ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Structural Changes ◽  
Deinococcus Radiodurans ◽  
Red Light ◽  
Light Responses ◽  
Structural Mechanism ◽  
Weakly Coupled ◽  
Activity State ◽  
Conserved Tyrosine

Phytochromes are photoreceptors in plants, fungi, and various microorganisms and cycle between metastable red light–absorbing (Pr) and far-red light–absorbing (Pfr) states. Their light responses are thought to follow a conserved structural mechanism that is triggered by isomerization of the chromophore. Downstream structural changes involve refolding of the so-called tongue extension of the phytochrome-specific GAF-related (PHY) domain of the photoreceptor. The tongue is connected to the chromophore by conserved DIP and PRXSF motifs and a conserved tyrosine, but the role of these residues in signal transduction is not clear. Here, we examine the tongue interactions and their interplay with the chromophore by substituting the conserved tyrosine (Tyr263) in the phytochrome from the extremophile bacterium Deinococcus radiodurans with phenylalanine. Using optical and FTIR spectroscopy, X-ray solution scattering, and crystallography of chromophore-binding domain (CBD) and CBD–PHY fragments, we show that the absence of the Tyr263 hydroxyl destabilizes the β-sheet conformation of the tongue. This allowed the phytochrome to adopt an α-helical tongue conformation regardless of the chromophore state, hence distorting the activity state of the protein. Our crystal structures further revealed that water interactions are missing in the Y263F mutant, correlating with a decrease of the photoconversion yield and underpinning the functional role of Tyr263 in phytochrome conformational changes. We propose a model in which isomerization of the chromophore, refolding of the tongue, and globular conformational changes are represented as weakly coupled equilibria. The results also suggest that the phytochromes have several redundant signaling routes.

scholarly journals Light-Dependent Regulation of Cyanobacterial Phytochrome Expression

2000 ◽  
Vol 182 (1) ◽  
pp. 38-44 ◽  
Author(s):  
M. García-Domínguez ◽  
M. I. Muro-Pastor ◽  
J. C. Reyes ◽  
F. J. Florencio
Keyword(s):  
Response Regulator ◽  
Electron Flow ◽  
Spectral Characteristics ◽  
Red Light ◽  
Mrna Levels ◽  
Two Component System ◽  
Dark Light ◽  
Transcript Stability ◽  
Normal Light

ABSTRACT A histidine kinase protein (Cph1) with sequence homology and spectral characteristics very similar to those of the plant phytochrome has been recently identified in the cyanobacteriumSynechocystis sp. strain PCC 6803. Cph1 together with Rcp1 (a protein homologue to the response regulator CheY) forms a light-regulated two-component system whose function is presently unknown. Levels of cph1 rcp1 mRNA increase in the dark and decrease upon reillumination. A dark-mediated increase in cph1 rcp1 mRNA levels was inhibited by the presence of glucose, but not by inhibition of the photosynthetic electron flow. The half-life ofcph1 rcp1 transcript in the light was about fourfold shorter than in the dark, indicating that control of cph1 rcp1 transcript stability is one of the mechanisms by which light regulates expression of the cyanobacterial phytochrome. After 15 min of darkness, 3-min pulses of red, blue, green, and far-red light were equally efficient in decreasing the cph1 rcp1 mRNA levels. Red light downregulation was not reversed by far-red light, suggesting that cph1 rcp1 mRNA levels are not controlled by a phytochrome-like photoreceptor. Furthermore, aSynechocystis strain containing an H538R Cph1 point mutation, unable to phosphorylate Rcp1, shows normal light-dark regulation of the cph1 rcp1 transcript levels. Our data suggest a role of cyanobacterial phytochrome in the control of processes required for adaptation in light-dark and dark-light transitions.

Maize AUXIN-BINDING PROTEIN 1 and AUXIN-BINDING PROTEIN 4 impact on leaf growth, elongation, and seedling responsiveness to auxin and light

Botany ◽  
2012 ◽  
Vol 90 (10) ◽  
pp. 990-1006 ◽  
Author(s):  
Dejana Jurišić-Knežev ◽  
Mária Čudejková ◽  
David Zalabák ◽  
Marta Hlobilová ◽  
Jakub Rolčík ◽  
...  
Keyword(s):  
Binding Protein ◽  
Leaf Growth ◽  
Red Light ◽  
Maize Seedlings ◽  
Exogenous Auxin ◽  
Auxin Binding ◽  
Auxin Binding Protein ◽  
Auxin Binding Proteins ◽  
The Relationship

In maize, at least five auxin-binding proteins (ABPs) have been identified, yet their functions remain unclear. The present study reports the use of maize abp1, abp4, and abp1abp4 mutants to investigate the role of ABPs during maize growth and development. Single and double abp mutant plants grown in a greenhouse differ from the wild type (WT) in their leaf declination and leaf blade growth. The effect of the dark (D), blue light (BL), red light (RL), and exogenous auxin on the development of mutant seedlings was also studied. Relative to WT, etiolated mutant seedlings were shorter and showed a reduced responsiveness to exogenous auxin. In BL or RL, the responsiveness of maize seedlings to auxin was distinctly less than in D. The reducing effect of light on seedling responsiveness to auxin is mediated at least by phytochromes. The suppression of ABP1 and (or) ABP4 led to a distinct accumulation of free indole-3-acetic acid (IAA) in etiolated and light-grown seedling organs. We concluded that ABP1 and ABP4 participate in the growth of maize seedlings, mediate seedling responses to auxin, and interact with light signaling pathway(s). We also deduce a functional interaction between ABP1 and ABP4, which is that the relationship between them is light-, organ- and response-dependent.

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