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https://www.readbyqxmd.com/read/28559328/photoactivation-mechanism-of-a-carotenoid-based-photoreceptor
#1
Sepalika Bandara, Zhong Ren, Lu Lu, Xiaoli Zeng, Heewhan Shin, Kai-Hong Zhao, Xiaojing Yang
Photoprotection is essential for efficient photosynthesis. Cyanobacteria have evolved a unique photoprotective mechanism mediated by a water-soluble carotenoid-based photoreceptor known as orange carotenoid protein (OCP). OCP undergoes large conformational changes in response to intense blue light, and the photoactivated OCP facilitates dissipation of excess energy via direct interaction with allophycocyanins at the phycobilisome core. However, the structural events leading up to the OCP photoactivation remain elusive at the molecular level...
May 30, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28487255/disruption-of-adolescents-circadian-clock-the-vicious-circle-of-media-use-exposure-to-light-at-night-sleep-loss-and-risk-behaviors
#2
Yvan Touitou, David Touitou, Alain Reinberg
Although sleep is a key element in adolescent development, teens are spending increasing amounts of time online with health risks related to excessive use of electronic media (computers, smartphones, tablets, consoles…) negatively associated with daytime functioning and sleep outcomes. Adolescent sleep becomes irregular, shortened and delayed in relation with later sleep onset and early waking time due to early school starting times on weekdays which results in rhythm desynchronization and sleep loss. In addition, exposure of adolescents to the numerous electronic devices prior to bedtime has become a great concern because LEDs emit much more blue light than white incandescent bulbs and compact fluorescent bulbs and have therefore a greater impact on the biological clock...
May 12, 2017: Journal of Physiology, Paris
https://www.readbyqxmd.com/read/28472717/photoreceptor-dependent-regulation-of-photoprotection
#3
REVIEW
Guillaume Allorent, Dimitris Petroutsos
In photosynthetic organisms, proteins in the light-harvesting complex (LHC) harvest light energy to fuel photosynthesis, whereas photoreceptor proteins are activated by the different wavelengths of the light spectrum to regulate cellular functions. Under conditions of excess light, blue-light photoreceptors activate chloroplast avoidance movements in sessile plants, and blue- and green-light photoreceptors cause motile algae to swim away from intense light. Simultaneously, LHCs switch from light-harvesting mode to energy-dissipation mode, which was thought to be independent of photoreceptor-signaling up until recently...
May 1, 2017: Current Opinion in Plant Biology
https://www.readbyqxmd.com/read/28419325/dissecting-molecular-and-physiological-response-mechanisms-to-high-solar-radiation-in-cyanic-and-acyanic-leaves-a-case-study-on-red-and-green-basil
#4
Massimiliano Tattini, Federico Sebastiani, Cecilia Brunetti, Alessio Fini, Sara Torre, Antonella Gori, Mauro Centritto, Francesco Ferrini, Marco Landi, Lucia Guidi
Photosynthetic performance and the expression of genes involved in light signaling and the biosynthesis of isoprenoids and phenylpropanoids were analysed in green ('Tigullio', TIG) and red ('Red Rubin', RR) basil. The aim was to detect the physiological and molecular response mechanisms to high sunlight. The attenuation of blue-green light by epidermal anthocyanins was shown to evoke shade-avoidance responses with consequential effects on leaf morpho-anatomical traits and gas exchange performance. Red basil had a lower mesophyll conductance, partially compensated by the less effective control of stomatal movements, in comparison with TIG...
April 1, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28392641/low-level-light-therapy-with-410-nm-light-emitting-diode-suppresses-collagen-synthesis-in-human-keloid-fibroblasts-an-in-vitro-study
#5
Hyun Soo Lee, Soo-Eun Jung, Sue Kyung Kim, You-Sun Kim, Seonghyang Sohn, You Chan Kim
BACKGROUND: Keloids are characterized by excessive collagen deposition in the dermis, in which transforming growth factor β (TGF-β)/Smad signaling plays an important role. Low-level light therapy (LLLT) is reported as effective in preventing keloids in clinical reports, recently. To date, studies investigating the effect of LLLT on keloid fibroblasts are extremely rare. OBJECTIVE: We investigated the effect of LLLT with blue (410 nm), red (630 nm), and infrared (830 nm) light on the collagen synthesis in keloid fibroblasts...
April 2017: Annals of Dermatology
https://www.readbyqxmd.com/read/28391046/structure-and-functions-of-orange-carotenoid-protein-homologs-in-cyanobacteria
#6
REVIEW
Han Bao, Matthew R Melnicki, Cheryl A Kerfeld
Rapidly-induced photoprotection in cyanobacteria involves thermal dissipation of excess energy absorbed by the phycobilisome (PBS), the primary light-harvesting antenna. This process is called non-photochemical quenching (NPQ), and is mediated by a water-soluble photoactive protein, the Orange Carotenoid Protein (OCP). The OCP is structurally and functionally modular, consisting of a sensor domain, an effector domain, and a carotenoid. Blue-green light induces a structural transition of the OCP from the orange inactive form, OCP(o), to the red active form, OCP(R)...
April 5, 2017: Current Opinion in Plant Biology
https://www.readbyqxmd.com/read/28325907/photosensitization-of-tio2-nanofibers-by-ag2s-with-the-synergistic-effect-of-excess-surface-ti-3-states-for-enhanced-photocatalytic-activity-under-simulated-sunlight
#7
Samina Ghafoor, Sadia Ata, Nasir Mahmood, Salman Noshear Arshad
TiO2 nanofibers, with mean diameter ~200 nm, were fabricated by electrospinning and successfully photosensitized with low bandgap Ag2S nanoparticles of 11, 17, 23 and 40 nm mean sizes, with corresponding loading of 4, 10, 18 and 29 wt.% Ag2S, respectively. 17 nm Ag2S@TiO2 nanofibers exhibited optimal activity in the photodegradation of methylene blue under simulated sunlight with pseudo-first order rate constant of 0.019 min(-1) compared to 0.009 min(-1) for pure TiO2 nanofibers. In spite of greater visible-light absorption and reduced bandgap, larger than 17 nm Ag2S nanoparticles exhibited sluggish photodegradation kinetics probably due to less photo-induced carriers generation in TiO2 and reduced electron injection rates from the larger sized Ag2S into TiO2...
March 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28317022/water-dispersible-silica-coated-upconverting-liposomes-can-a-thin-silica-layer-protect-tta-uc-against-oxygen-quenching
#8
Sven H C Askes, Vincent C Leeuwenburgh, Wim Pomp, Hadi Arjmandi-Tash, Stefania Tanase, Thomas Schmidt, Sylvestre Bonnet
Light upconversion by triplet-triplet annihilation (TTA-UC) in nanoparticles has received considerable attention for bioimaging and light activation of prodrugs. However, the mechanism of TTA-UC is inherently sensitive for quenching by molecular oxygen. A potential oxygen protection strategy is the coating of TTA-UC nanoparticles with a layer of oxygen-impermeable material. In this work, we explore if (organo)silica can fulfill this protecting role. Three synthesis routes are described for preparing water-dispersible (organo)silica-coated red-to-blue upconverting liposomes...
March 13, 2017: ACS Biomaterials Science & Engineering
https://www.readbyqxmd.com/read/28240871/photoinduced-stark-effects-and-mechanism-of-ion-displacement-in-perovskite-solar-cell-materials
#9
Meysam Pazoki, T Jesper Jacobsson, Jolla Kullgren, Erik M J Johansson, Anders Hagfeldt, Gerrit Boschloo, Tomas Edvinsson
Organometallic halide perovskites (OMHPs) have recently emerged as a promising class of materials in photovoltaic technology. Here, we present an in-depth investigation of the physics in these systems by measuring the photoinduced absorption (PIA) in OMHPs as a function of materials composition, excitation wavelength, and modulation frequency. We report a photoinduced Stark effect that depends on the excitation wavelength and on the dipole strength of the monovalent cations in the A position of the ABX3 perovskite...
March 28, 2017: ACS Nano
https://www.readbyqxmd.com/read/28236074/interaction-of-the-signaling-state-analog-and-the-apoprotein-form-of-the-orange-carotenoid-protein-with-the-fluorescence-recovery-protein
#10
Marcus Moldenhauer, Nikolai N Sluchanko, Neslihan N Tavraz, Cornelia Junghans, David Buhrke, Mario Willoweit, Leonardo Chiappisi, Franz-Josef Schmitt, Vladana Vukojević, Evgeny A Shirshin, Vladimir Y Ponomarev, Vladimir Z Paschenko, Michael Gradzielski, Eugene G Maksimov, Thomas Friedrich
Photoprotection in cyanobacteria relies on the interplay between the orange carotenoid protein (OCP) and the fluorescence recovery protein (FRP) in a process termed non-photochemical quenching, NPQ. Illumination with blue-green light converts OCP from the basic orange state (OCP(O)) into the red-shifted, active state (OCP(R)) that quenches phycobilisome (PBs) fluorescence to avoid excessive energy flow to the photosynthetic reaction centers. Upon binding of FRP, OCP(R) is converted to OCP(O) and dissociates from PBs; however, the mode and site of OCP(R)/FRP interactions remain elusive...
February 24, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28192917/simple-reagentless-quantification-of-total-bilirubin-in-blood-via-microfluidic-phototreatment-and-image-analysis
#11
Brandon L Thompson, Sarah L Wyckoff, Doris M Haverstick, James P Landers
Total bilirubin (T-Bil) is an important clinical diagnostic marker that is measured frequently by physicians to assist in the diagnosis, treatment, and monitoring of multiple medical conditions. The work demonstrated here utilizes the 48-year-old mechanism of phototherapy that is commonly implemented in the treatment of infants with exaggerated physiologic and pathologic jaundice but adapts it to the microfluidic level for the ultimate purpose of total bilirubin quantitation. After acquisition of a small volume of blood (<10 μL) and through subsequent separation (plasma + red blood cells), a 3 μL plasma sample was imaged by a portable scanner and analyzed through a custom algorithm for color intensity...
February 13, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28188273/the-ropgef2-rop7-rop2-pathway-activated-by-phyb-suppresses-red-light-induced-stomatal-opening
#12
Wei Wang, Zhao Liu, Li-Juan Bao, Sha-Sha Zhang, Chun-Guang Zhang, Xin Li, Hai-Xia Li, Xiao-Lu Zhang, Atle Magnar Bones, Zhen-Biao Yang, Yu-Ling Chen
Circadian rhythm of stomatal aperture is mainly regulated by light/darkness. Blue and red light induce stomatal opening through different mechanisms that are mediated by special receptors. ROP2, a member of Rho GTPase family in Arabidopsis (Arabidopsisthaliana), has been found to negatively regulate light-induced stomatal opening. However, the upstream guanine nucleotide exchange factor (GEF) RopGEFs have not been revealed, and it is unclear which photoreceptor is required for the action of RopGEFs-ROPs. Here, we showed that RopGEF2 acted as a negative regulator in phytochrome B (phyB)-mediated red light-induced stomatal opening...
June 2017: Plant Physiology
https://www.readbyqxmd.com/read/28063778/violet-light-exposure-can-be-a-preventive-strategy-against-myopia-progression
#13
Hidemasa Torii, Toshihide Kurihara, Yuko Seko, Kazuno Negishi, Kazuhiko Ohnuma, Takaaki Inaba, Motoko Kawashima, Xiaoyan Jiang, Shinichiro Kondo, Maki Miyauchi, Yukihiro Miwa, Yusaku Katada, Kiwako Mori, Keiichi Kato, Kinya Tsubota, Hiroshi Goto, Mayumi Oda, Megumi Hatori, Kazuo Tsubota
Prevalence of myopia is increasing worldwide. Outdoor activity is one of the most important environmental factors for myopia control. Here we show that violet light (VL, 360-400nm wavelength) suppresses myopia progression. First, we confirmed that VL suppressed the axial length (AL) elongation in the chick myopia model. Expression microarray analyses revealed that myopia suppressive gene EGR1 was upregulated by VL exposure. VL exposure induced significantly higher upregulation of EGR1 in chick chorioretinal tissues than blue light under the same conditions...
February 2017: EBioMedicine
https://www.readbyqxmd.com/read/28018376/polychromatic-supplemental-lighting-from-underneath-canopy-is-more-effective-to-enhance-tomato-plant-development-by-improving-leaf-photosynthesis-and-stomatal-regulation
#14
Yu Song, Chengyao Jiang, Lihong Gao
Light insufficient stress caused by canopy interception and mutual shading is a major factor limiting plant growth and development in intensive crop cultivation. Supplemental lighting can be used to give light to the lower canopy leaves and is considered to be an effective method to cope with low irradiation stress. Leaf photosynthesis, stomatal regulation, and plant growth and development of young tomato plants were examined to estimate the effects of supplemental lighting with various composite spectra and different light orientations...
2016: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28003770/advances-in-the-management-of-erythropoietic-protoporphyria-role-of-afamelanotide
#15
REVIEW
Ashley M Lane, Jerome T McKay, Herbert L Bonkovsky
Erythropoietic protoporphyria (EPP) and the phenotypically similar disease X-linked protoporphyria (XLPP) are inherited cutaneous porphyrias characterized clinically by acute non-blistering photosensitivity, intolerance to sunlight, and significantly reduced quality of life. They are due to marked overproduction of protoporphyrin (PP) chiefly by erythroblasts and reticulocytes. In EPP, the underlying genetic defect is in the ferrochelatase gene, which encodes the final enzyme in the heme synthetic pathway. In XLPP, the genetic defect is a gain-of-function mutation, usually a four-base deletion, in the gene that encodes the enzyme 5-aminolevulinic acid synthase-2, the first and rate-controlling enzyme of heme synthesis in developing red blood cells...
2016: Application of Clinical Genetics
https://www.readbyqxmd.com/read/27849028/evidences-for-cooperative-resonance-assisted-hydrogen-bonds-in-protein-secondary-structure-analogs
#16
Yu Zhou, Geng Deng, Yan-Zhen Zheng, Jing Xu, Hamad Ashraf, Zhi-Wu Yu
Cooperative behaviors of the hydrogen bonding networks in proteins have been discovered for a long time. The structural origin of this cooperativity, however, is still under debate. Here we report a new investigation combining excess infrared spectroscopy and density functional theory calculation on peptide analogs, represented by N-methylformamide (NMF) and N-methylacetamide (NMA). Interestingly, addition of the strong hydrogen bond acceptor, dimethyl sulfoxide, to the pure analogs caused opposite effects, namely red- and blue-shift of the N-H stretching infrared absorption in NMF and NMA, respectively...
November 16, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27662784/mechanisms-of-phosphene-generation-in-ocular-proton-therapy-as-related-to-space-radiation-exposure
#17
D Chuard, V Anthonipillai, R Dendale, C Nauraye, E Khan, C Mabit, L De Marzi, L Narici
Particle therapy provides an opportunity to study the human response to space radiation in ground-based facilities. On this basis, a study of light flashes analogous to astronauts' phosphenes reported by patients undergoing ocular proton therapy has been undertaken. The influence of treatment parameters on phosphene generation was investigated for 430 patients treated for a choroidal melanoma at the proton therapy centre of the Institut Curie (ICPO) in Orsay, France, between 2008 and 2011. 60% of them report light flashes, which are predominantly (74%) blue...
August 2016: Life Sciences in Space Research
https://www.readbyqxmd.com/read/27626383/a-blue-light-photoreceptor-mediates-the-feedback-regulation-of-photosynthesis
#18
Dimitris Petroutsos, Ryutaro Tokutsu, Shinichiro Maruyama, Serena Flori, Andre Greiner, Leonardo Magneschi, Loic Cusant, Tilman Kottke, Maria Mittag, Peter Hegemann, Giovanni Finazzi, Jun Minagawa
In plants and algae, light serves both as the energy source for photosynthesis and a biological signal that triggers cellular responses via specific sensory photoreceptors. Red light is perceived by bilin-containing phytochromes and blue light by the flavin-containing cryptochromes and/or phototropins (PHOTs), the latter containing two photosensory light, oxygen, or voltage (LOV) domains. Photoperception spans several orders of light intensity, ranging from far below the threshold for photosynthesis to values beyond the capacity of photosynthetic CO2 assimilation...
September 22, 2016: Nature
https://www.readbyqxmd.com/read/27607687/leaky-mode-waveguide-modulators-with-high-deflection-angle-for-use-in-holographic-video-displays
#19
Kamran Qaderi, Daniel E Smalley
Film display holograms typically diffract light over a wide enough view-angle to be viewed, directly, without intervening optics. However, all holographic video displays (with the exception of eye-tracked systems) must use optics beyond the hologram surface to overcome the challenges of small display extent and low diffraction angle by using some form of demagnification and derotation (i.e. angle magnification and optical multiplexing). We report a leaky mode waveguide spatial light modulator with sufficiently high angular diffraction to obviate the need for demagnification in scanned aperture systems...
September 5, 2016: Optics Express
https://www.readbyqxmd.com/read/27594835/flash-and-freeze-coordinating-optogenetic-stimulation-with-rapid-freezing-to-visualize-membrane-dynamics-at-synapses-with-millisecond-resolution
#20
Shigeki Watanabe
Electron microscopy depicts subcellular structures at synapses exquisitely but only captures static images. To visualize membrane dynamics, we have developed a novel technique, called flash-and-freeze, which induces neuronal activity with a flash of light and captures the membrane dynamics by rapid freezing. For characterizing membrane movements during synaptic transmission, a light-sensitive cation channel, channelrhodopsin, is heterologously expressed in mouse hippocampal neurons or in Caenorhabditis elegans motor neurons...
2016: Frontiers in Synaptic Neuroscience
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