Persistence of phytochrome-mediated germination control in lettuce seeds for 1 year following a single monochromatic light flash

1972 ◽  
Vol 50 (4) ◽  
pp. 687-689 ◽  
Author(s):  
William Vidaver ◽  
A. I-hsiung Hsiao
Keyword(s):  
Light Flash ◽  
Red Light ◽  
Monochromatic Light ◽  
Entire Period ◽  
Lettuce Seeds ◽  
Light Flashes

The effects of red or far-red light flashes on partially hydrated lettuce seeds were found to be undiminished by subsequent dry, dark storage for more than 1 year before germination. Upon rehydration of the seeds photoreversal of the latent response could be induced by a red or far-red light flash at any time during the entire period.

ACTION AND INTERACTION OF MONOCHROMATIC LIGHT ON PHOSPHATE METABOLISM OF GERMINATING LETTUCE SEEDS

1962 ◽  
Vol 40 (7) ◽  
pp. 965-974 ◽  
Author(s):  
Kenneth Surrey
Keyword(s):  
Energy Flow ◽  
Spectral Band ◽  
Red Light ◽  
Monochromatic Light ◽  
Lettuce Seed ◽  
Phosphate Metabolism ◽  
Lettuce Seeds ◽  
Phytochrome System ◽  
Lettuce Seed Germination ◽  
Partial Suppression

A previously described photoresponse of lettuce seed germination to red and far-red light is shown to be paralleled by a response of phosphate metabolic activity: (1) When seeds were continuously irradiated, red light accelerated and far-red suppressed their phosphate uptake and esterification. (2) The influence of monochromatic light on phosphate metabolism of seeds, determined after 36 and 64 hours of germination, respectively, indicated maximum potentiation between 550 and 650 mμ, maximum suppression beyond 700 mμ, and partial suppression at 475 mμ. Stimulation was encountered at 400 mμ, but with shorter wavelengths of the ultraviolet spectrum, suppression appeared again. (3) Photoactivation of phosphate metabolism in response to each of the three loci (550, 600, and 650 mμ, i.e., green, orange, and red light, respectively) of the potentiating spectral band was reversed by far-red (750 mμ) light. These activations and inhibitions could be reversed several times in an alternating sequence. Complete reversibility depended entirely upon the magnitudes of the radiant flux for the two counteracting wavelengths, and this was characteristic for each pair of antagonistic wavelengths. In view of the association of phytochrome with the isolated mitochondria and of the specific manner in which their phosphorylation activity is influenced by light, it is suggested that a part of the energy flow required for cellular development may be channeled through the mitochondrial–phytochrome system.

scholarly journals THE TIME DIFFERENCE IN EMISSION OF LIGHT AND PRESSURE PULSES FROM OSCILLATING BUBBLES

2018 ◽  
Vol 58 (5) ◽  
pp. 323
Author(s):  
Karel Vokurka
Keyword(s):  
Bubble Size ◽  
Light Flash ◽  
Time Difference ◽  
Intensity Maximum ◽  
Bubble Oscillation ◽  
Maximum Value ◽  
Oscillating Bubbles ◽  
Oscillation Intensity ◽  
Pressure Pulses ◽  
Light Flashes

Oscillations of spark-generated bubbles are studied experimentally. In this work, an attention is paid to the time difference in the radiation of light flashes and pressure pulses from a bubble at the final stages of the first bubble contraction and the early stages of the first bubble expansion. It is found that light and pressure pulses are not radiated synchronously. In some experiments, the light flashes are radiated before the pressure pulses by a few μs and in other experiments, the light flashes are radiated later than the pressure pulses by a few μs. The time difference in the radiation of the two pulses is examined in detail in relation with the bubble size, bubble oscillation intensity, maximum value of the light flash and the width of the light flash. It is shown that the magnitude of the time differences is very weakly correlated with the bubble size, intensity of oscillation and intensity of the light flashes and that the magnitude of the time differences is only moderately correlated with the light flashes widths.

Cyclic Electron Flow Around Photosystem II as Examined by Photosynthetic Oxygen Evolution Induced by Short Light Flashes

1997 ◽  
Vol 52 (3-4) ◽  
pp. 175-179 ◽  
Author(s):  
W. I. Gruszecki ◽  
K. Strzałka ◽  
A. Radunz ◽  
G. H. Schmid
Keyword(s):  
Photosystem Ii ◽  
Oxygen Evolution ◽  
Molecular Mechanisms ◽  
Electron Flow ◽  
Red Light ◽  
Cyclic Electron Flow ◽  
Photosynthetic Oxygen Evolution ◽  
Absorption Region ◽  
Photosynthetic Oxygen ◽  
Light Flashes

Abstract Photosynthetic oxygen evolution from photosystem II particles was analyzed as consequence of a train of short (5 μs) flashes of different light quality and different intensities to study cyclic electron flow around photosystem II. Damped oscillations of the amplitudes of O2-evolution corresponding to a flash sequence were fitted numerically and analyzed in terms of a nonhomogeneous distribution of misses, represented by the probability parameter αi. Application of red light, known to promote cyclic electron flow around photosystem II (Gruszecki et al., 1995) results in a considerable increase of all αi, indicating that at the molecular level the misses may be interpreted as resulting from a competition for the reduction of oxidized P680 between cyclic electron flow and the electron flow coming from the water splitting enzyme. In accordance with previous findings, application of light flashes of the spectrum covering the absorption region of carotenoids resulted in an inhibition of cyclic electron flow and a pronounced decrease of the level of the miss parameter. Possible molecular mechanisms for the activity control of this cyclic electron transport around photosystem II by carotenoids are discussed.

Effects of different monochromatic LED light colours on fear reactions and physiological responses in Mulard ducks

2017 ◽  
Vol 57 (6) ◽  
pp. 1128 ◽  
Author(s):  
Radi A. Mohamed ◽  
Usama A. Abou-Ismail ◽  
Mustafa Shukry
Keyword(s):  
Tonic Immobility ◽  
Leukocyte Count ◽  
Physiological Responses ◽  
Red Light ◽  
Monochromatic Light ◽  
Plasma Concentrations ◽  
Green Light ◽  
Total Leukocyte Count ◽  
Physiological Indicators ◽  
And Performance

Although the effects of monochromatic light on behaviour and performance of birds have been extensively studied, it is not known how rearing Mulard ducks in different monochromatic lights affects their fear reactions, physiological responses to stress and welfare. A total of 108 newly hatched Mulard ducks, representing three replicates, were housed in either blue light (BL), green light (GL), red light (RL) or white light (WL) for 12 weeks. Ducks were exposed to a light/dark schedule of 23 L/1 D, and food and water were provided ad libitum. At the beginning of the 13th week of the rearing period, behavioural measurements of fear were assessed by using a tonic immobility test, open field test and fear of man test. Physiological responses of the birds to stress such as heterophil : lymphocyte ratio, total leukocyte count and plasma concentrations of corticosterone were also assessed. Results demonstrated that birds exposed to both RL and WL displayed higher levels of behavioural indicators of fear including tonic immobility durations (P < 0.01), latency to first immobilisation (P < 0.001) and avoidance of man index (P < 0.001), and higher levels of physiological indicators of stress such as heterophil : lymphocyte ratios (P < 0.001) and plasmas concentrations of corticosterone (P < 0.001), and lower total leukocytic counts (P < 0.01) compared with birds exposed to either BL or GL. Rearing Mulard ducks in BL or GL appeared to reduce their fear reactions and physiological responses to stress and to enhance their ability to cope with the environment and may therefore improve their welfare.

scholarly journals An in vitro cell irradiation protocol for testing photopharmaceuticals and the effect of blue, green, and red light on human cancer cell lines

2016 ◽  
Vol 15 (5) ◽  
pp. 644-653 ◽  
Author(s):  
S. L. Hopkins ◽  
B. Siewert ◽  
S. H. C. Askes ◽  
P. Veldhuizen ◽  
R. Zwier ◽  
...  
Keyword(s):  
Cell Lines ◽  
Cancer Cell ◽  
Human Cancer ◽  
Red Light ◽  
Monochromatic Light ◽  
Cancer Cell Lines ◽  
Human Cancer Cell ◽  
Human Cancer Cell Lines ◽  
Cell Irradiation

A LED-based cell irradiation system was built that can irradiate a 96-well plate with monochromatic light at controlled temperature and with a built-in dark control. This system was used to study the response of six human cancer cell lines to blue, green, and red light.

The growth physics and water relations of red-light-induced germination in lettuce seeds

Planta ◽  
1971 ◽  
Vol 101 (1) ◽  
pp. 1-25 ◽  
Author(s):  
Murray W. Nabors ◽  
Anton Lang
Keyword(s):  
Water Relations ◽  
Red Light ◽  
Lettuce Seeds
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