scholarly journals The absence of attenuating effect of red light exposure on pre-existing melanopsin-driven post-illumination pupil response

2016 ◽  
Vol 124 ◽  
pp. 59-65 ◽  
Author(s):  
Shaobo Lei ◽  
Herbert C. Goltz ◽  
Jaime C. Sklar ◽  
Agnes M.F. Wong
Keyword(s):  
Light Exposure ◽  
Red Light ◽  
Pupil Response

scholarly journals Artificial complementary chromatic acclimation gene expression system in Escherichia coli

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Dwi Ariyanti ◽  
Kazunori Ikebukuro ◽  
Koji Sode
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Light Exposure ◽  
Expression System ◽  
Red Light ◽  
Green Light ◽  
Light Illumination ◽  
Multiple Gene ◽  
Gene Expression System ◽  
Chromatic Acclimation

Abstract Background The development of multiple gene expression systems, especially those based on the physical signals, such as multiple color light irradiations, is challenging. Complementary chromatic acclimation (CCA), a photoreversible process that facilitates the control of cellular expression using light of different wavelengths in cyanobacteria, is one example. In this study, an artificial CCA systems, inspired by type III CCA light-regulated gene expression, was designed by employing a single photosensor system, the CcaS/CcaR green light gene expression system derived from Synechocystis sp. PCC6803, combined with G-box (the regulator recognized by activated CcaR), the cognate cpcG2 promoter, and the constitutively transcribed promoter, the PtrcΔLacO promoter. Results One G-box was inserted upstream of the cpcG2 promoter and a reporter gene, the rfp gene (green light-induced gene expression), and the other G-box was inserted between the PtrcΔLacO promoter and a reporter gene, the bfp gene (red light-induced gene expression). The Escherichia coli transformants with plasmid-encoded genes were evaluated at the transcriptional and translational levels under red or green light illumination. Under green light illumination, the transcription and translation of the rfp gene were observed, whereas the expression of the bfp gene was repressed. Under red light illumination, the transcription and translation of the bfp gene were observed, whereas the expression of the rfp gene was repressed. During the red and green light exposure cycles at every 6 h, BFP expression increased under red light exposure while RFP expression was repressed, and RFP expression increased under green light exposure while BFP expression was repressed. Conclusion An artificial CCA system was developed to realize a multiple gene expression system, which was regulated by two colors, red and green lights, using a single photosensor system, the CcaS/CcaR system derived from Synechocystis sp. PCC6803, in E. coli. The artificial CCA system functioned repeatedly during red and green light exposure cycles. These results demonstrate the potential application of this CCA gene expression system for the production of multiple metabolites in a variety of microorganisms, such as cyanobacteria.

Use of A GAS Jet Technique to Prepare Microcrystalline Silicon Based Solar Cells at High I-Layer Deposition Rates

1999 ◽  
Vol 557 ◽  
Author(s):  
S.J. Jones ◽  
R. Crucet ◽  
X. Deng ◽  
J. Doehler ◽  
R. Kopf ◽  
...  
Keyword(s):  
Solar Cells ◽  
Peak Power ◽  
Light Exposure ◽  
Red Light ◽  
Gas Jet ◽  
Scale Production ◽  
Microcrystalline Silicon ◽  
Deposition Rates ◽  
Layer Deposition ◽  
Power Outputs

AbstractUsing a Gas Jet thin film deposition technique, microcrystalline silicon (μc-Si) materials were prepared at rates as high as 15-20 Å/s. The technique involves the use of a gas jet flow that is subjected to a high intensity microwave source. The quality of the material has been optimized through the variation of a number of deposition conditions including the substrate temperature, the gas flows, and the applied microwave power. The best films were made using deposition rates near 16 Å/s. These materials have been used as i-layers for red light absorbing, nip single-junction solar cells. Using a 610nm cutoff filter which only allows red light to strike the device, pre-light soaked currents as high as 10 mA/cm2 and 2.2-2.3% red-light pre-light soaked peak power outputs have been obtained for cells with i-layer thicknesses near 1 micron. This compares with currents of 10-11 mA/cm2 and 4% initial red-light peak power outputs obtained for high efficiency amorphous silicon germanium alloy (a-SiGe:H) devices. The AM1.5 white light efficiencies for these microcrystalline cells are 5.9-6.0%. While the efficiencies for the a-SiGe:H cells degrade by 15-20% after long term light exposure, the efficiencies for the microcrystalline cells before and after prolonged light exposure are similar, within measurement error. Considering these results, the Gas Jet deposition method is a promising technique for the deposition of μc-Si solar cells due to the ability to achieve reasonable stable efficiencies for cells at i-layer deposition rates (16 Å/s) which make large-scale production economically feasible.

Prior Light Exposure Enhances the Pupil Response to Subsequent Short Wavelength (Blue) Light

2011 ◽  
Vol 02 (05) ◽  
Author(s):  
Michael Stormly Hansen ◽  
Birgit Sander ◽  
Aki Kawasaki ◽  
Adam Elias Brøndsted ◽  
Claus Nissen
Keyword(s):  
Blue Light ◽  
Short Wavelength ◽  
Light Exposure ◽  
Pupil Response

scholarly journals The Role of Leaves in Photocontrol of Flower Bud Abscission in Hibiscus rosa-sinensis L. `Nairobi'

2000 ◽  
Vol 125 (1) ◽  
pp. 31-35 ◽  
Author(s):  
Uulke van Meeteren ◽  
Annie van Gelder
Keyword(s):  
Light Quality ◽  
Light Exposure ◽  
Red Light ◽  
Light Conditions ◽  
Flower Bud ◽  
Light Emitting ◽  
Hibiscus Rosa Sinensis ◽  
Number Of Leaves ◽  
Whole Plants

When compared with exposure to darkness, exposing Hibiscus rosa-sinensis L. `Nairobi' plants to red light (635 to 685 nm, 2.9 μmol·m-2·s-1) delayed flower bud abscission, while exposure to far-red light (705 to 755 nm, 1.7 μmol·m-2·s-1) accelerated this process. Flower bud abscission in response to light quality appears to be controlled partly by the presence of leaves. The delay of bud abscission was positively correlated to the number of leaves being exposed to red light. Excluding the flower buds from exposure to red or far-red light, while exposing the remaining parts of the plants to these light conditions, did not influence the effects of the light exposure on bud abscission. Exposing only the buds to red light by the use of red light-emitting diodes (0.8 μmol·m-2·s-1) did not prevent dark-induced flower bud abscission. Exposing the whole plants, darkness or far-red light could only induce flower bud abscission when leaves were present; bud abscission was totally absent when all leaves were removed. To prevent flower bud abscission, leaves had to be removed before, or at the start of, the far-red light treatment. These results suggest that in darkness or far-red light, a flower bud abscission-promoting signal from the leaves may be involved.

Changes in Light and Dark Adapted Planarian Photoreceptors

1972 ◽  
Vol 30 ◽  
pp. 42-43
Author(s):  
Kay S. Carpenter ◽  
Michio Morita
Keyword(s):  
Experimental Animal ◽  
Photoreceptor Cell ◽  
Receptor Cell ◽  
Light Exposure ◽  
Red Light ◽  
Natural Light ◽  
Light Cycle ◽  
Dugesia Dorotocephala

The planarian Dugesia dorotocephala was used as the experimental animal to study the ultrastructure in the photoreceptor cell under different light parameters. The experimental groups studied were nine days dark adapted (DA), nine days natural light cycle (LA), and nine days dark adapted followed by ten minutes light exposure (DA + LE). A red light was used for feeding and cleaning the dark adapted animals. Fixation was in 2.5% glutaraldehyde followed by 1% OsO4.The most noticeable changes occured in the stalk area of the receptor cell located directly below the rhabdomeric microvilli. The mitochondria in light adapted animals were observed to exist in both swollen and contracted conditions.

scholarly journals Sustained effects of prior red light on pupil diameter and vigilance during subsequent darkness

2018 ◽  
Vol 285 (1883) ◽  
pp. 20180989 ◽  
Author(s):  
Wisse P. van der Meijden ◽  
Bart H. W. te Lindert ◽  
Jennifer R. Ramautar ◽  
Yishul Wei ◽  
Joris E. Coppens ◽  
...  
Keyword(s):  
Heart Rate ◽  
Light Exposure ◽  
Red Light ◽  
Sleep Onset ◽  
Response Speed ◽  
Vigilance Task ◽  
Environmental Light ◽  
Sustained Effects ◽  
And Performance ◽  
Wavelength Light

Environmental light can exert potent effects on physiology and behaviour, including pupil size, vigilance and sleep. Previous work showed that these non-image forming effects can last long beyond discontinuation of short -wavelength light exposure. The possible functional effects after switching off long -wavelength light, however, have been insufficiently characterized. In a series of controlled experiments in healthy adult volunteers, we evaluated the effects of five minutes of intense red light on physiology and performance during subsequent darkness. As compared to prior darkness, prior red light induced a subsequent sustained pupil dilation. Prior red light also increased subsequent heart rate and heart rate variability when subjects were asked to perform a sustained vigilance task during the dark exposure. While these changes suggest an increase in the mental effort required for the task, it could not prevent a post-red slowing of response speed. The suggestion that exposure to intense red light affects vigilance during subsequent darkness, was confirmed in a controlled polysomnographic study that indeed showed a post-red facilitation of sleep onset. Our findings suggest the possibility of using red light as a nightcap.

Photoinduced changes in amorphous selenium

2014 ◽  
Vol 92 (7/8) ◽  
pp. 663-666 ◽  
Author(s):  
F. Djefaflia ◽  
C. Mebarkia ◽  
A. Hafdallah ◽  
M.L. Benkhedir ◽  
A. Belfedal
Keyword(s):  
Thin Films ◽  
White Light ◽  
Room Temperature ◽  
Light Exposure ◽  
Red Light ◽  
Amorphous Selenium ◽  
Corning Glass ◽  
Visible Transmittance ◽  
Photoinduced Changes ◽  
Photoinduced Phenomena

Photoinduced phenomena in thin films of amorphous selenium (a-Se) have been a subject of intensive researches so far. Thin films of a-Se were deposited on corning glass by thermal evaporation, with several thicknesses. The influence of light exposure, with different colors (blue or red or natural white light), on the optical and structural properties of a-Se thin films was carried out by using ultraviolet–visible transmittance spectroscopy. It was found that the gap of the samples illuminated with blue and natural white light at room temperature shifts to lower energies. This photodarkening is stable at room temperature and is irreversible even after several days. On the other hand the photodarkening in the samples illuminated with red light is much smaller than that for samples illuminated with blue and natural white light. The photodarkening is accompanied by an increase in the refractive index. These results are discussed with results, previously obtained, about the photoinduced changes of the negative-U centers in, T– and T+, studied using time-of-flight (TOF) traces recorded on samples prepared in the same conditions. These TOF measurements show that the defect level T– at 0.4 eV above the valence band edge shifts to 0.5 eV under illumination with white light at room temperature. This effect is not seen if the illumination is done at 35 °C. These phenomena are attributed to nanocrystallization in the a-Se films.

Photodynamic Therapy for Head and Neck Cancer Xenografts in Athymic Mice

1986 ◽  
Vol 95 (5) ◽  
pp. 602-606 ◽  
Author(s):  
James H. Hill ◽  
Randall L. Plant ◽  
David M. Harris ◽  
Randal C. Paniello
Keyword(s):  
Photodynamic Therapy ◽  
Light Intensity ◽  
Head And Neck ◽  
Treatment Time ◽  
Light Exposure ◽  
Red Light ◽  
Human Head ◽  
Athymic Mice ◽  
Squamous Cancer ◽  
Argon Dye Laser

This study examines efficacy and optimal treatment variables of photodynamic therapy (PDT) for human head and neck squamous cancer (HNSC) xenografts in athymic mice. Two and four days after injection of hematoporphyrin derivative (HPD), tumors were illuminated with red light from an argon-dye laser. Sixty-three tumors were treated. With HPD dose and light intensity constant at 7.5 mg/kg and 100 mW/cm2, respectively, the extent of tumor necrosis was strongly dependent on duration of light exposure. There was no substantial difference in results for 30- and 60-minute treatment durations between animals injected with HPD 2 and 4 days before treatment. After 30 minutes treatment time, responses were seen in 8 of 10 mice (2 days post-HPD) and 11 of 12 mice (4 days post-HPD). After 60 minutes treatment time, toxicity was high. We conclude that, in this model, PDT is effective in selective killing of HNSC. For future comparison studies in this model, if the indicated HPD dose and light intensity are used we recommend a 2-day delay after HPD injection and a light exposure duration of 30 minutes

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