WorldWideScience

Sample records for human blue-light photoreceptor

  1. Nrf2 protects photoreceptor cells from photo-oxidative stress induced by blue light.

    Science.gov (United States)

    Chen, Wan-Ju; Wu, Caiying; Xu, Zhenhua; Kuse, Yoshiki; Hara, Hideaki; Duh, Elia J

    2017-01-01

    Oxidative stress plays a key role in age-related macular degeneration and hereditary retinal degenerations. Light damage in rodents has been used extensively to model oxidative stress-induced photoreceptor degeneration, and photo-oxidative injury from blue light is particularly damaging to photoreceptors. The endogenous factors protecting photoreceptors from oxidative stress, including photo-oxidative stress, are continuing to be elucidated. In this study, we evaluated the effect of blue light exposure on photoreceptors and its relationship to Nrf2 using cultured murine photoreceptor (661W) cells. 661W cells were exposed to blue light at 2500 lux. Exposure to blue light for 6-24 h resulted in a significant increase in intracellular reactive oxygen species (ROS) and death of 661W cells in a time-dependent fashion. Blue light exposure resulted in activation of Nrf2, as indicated by an increase in nuclear translocation of Nrf2. This was associated with a significant induction of expression of Nrf2 as well as an array of Nrf2 target genes, including antioxidant genes, as indicated by quantitative reverse transcription PCR (qRT-PCR). In order to determine the functional role of Nrf2, siRNA-mediated knockdown studies were performed. Nrf2-knockdown in 661W cells resulted in significant exacerbation of blue light-induced reactive oxygen species levels as well as cell death. Taken together, these findings indicate that Nrf2 is an important endogenous protective factor against oxidative stress in photoreceptor cells. This suggests that drugs targeting Nrf2 could be considered as a neuroprotective strategy for photoreceptors in AMD and other retinal conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Knockout of Ccr2 alleviates photoreceptor cell death in rodent retina exposed to chronic blue light.

    Science.gov (United States)

    Hu, Zizhong; Zhang, Yi; Wang, Junling; Mao, Pingan; Lv, Xuehua; Yuan, Songtao; Huang, Zhengru; Ding, Yuzhi; Xie, Ping; Liu, Qinghuai

    2016-11-10

    Age-related macular degeneration (AMD), the leading cause of visual loss after the age of 60 years, is a degenerative retinal disease involving a variety of environmental and hereditary factors. Although it has been implicated that immune system is involved in the disease progression, the exact role that microglia has is still unclear. Here we demonstrated that knockout of Ccr2 gene could alleviate photoreceptor cell death in mice retinas exposed to chronic blue light. In Ccr2(-/-) mice, a damaged microglia recruitment was shown in retina and this could protect the visual function in electroretinogram and alleviate the photoreceptor apoptosis, which thus helped attenuate the blue light-induced retinopathy. We further found an increased co-location of NLRP3, Iba-1, and IL-1β in fluorescence and a concomitant increased protein expression of NLRP3, caspase-1, and IL-1β in western blotting in chronic blue light-induced retinopathy. Moreover, the activation of microglia and their cellular NLRP3 inflammasomes occurred as an earlier step before the structural and functional damage of the mice retinas, which collectively supported that microglial NLRP3 inflammasome might be the key to the chronic blue light-induced retinopathy.

  3. A blue-light photoreceptor mediates the feedback regulation of photosynthesis.

    Science.gov (United States)

    Petroutsos, Dimitris; Tokutsu, Ryutaro; Maruyama, Shinichiro; Flori, Serena; Greiner, Andre; Magneschi, Leonardo; Cusant, Loic; Kottke, Tilman; Mittag, Maria; Hegemann, Peter; Finazzi, Giovanni; Minagawa, Jun

    2016-09-22

    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. Excess light may cause oxidative damage and cell death, processes prevented by enhanced thermal dissipation via high-energy quenching (qE), a key photoprotective response. Here we show the existence of a molecular link between photoreception, photosynthesis, and photoprotection in the green alga Chlamydomonas reinhardtii. We show that PHOT controls qE by inducing the expression of the qE effector protein LHCSR3 (light-harvesting complex stress-related protein 3) in high light intensities. This control requires blue-light perception by LOV domains on PHOT, LHCSR3 induction through PHOT kinase, and light dissipation in photosystem II via LHCSR3. Mutants deficient in the PHOT gene display severely reduced fitness under excessive light conditions, indicating that the sensing, utilization, and dissipation of light is a concerted process that plays a vital role in microalgal acclimation to environments of variable light intensities.

  4. Damage of photoreceptor-derived cells in culture induced by light emitting diode-derived blue light.

    Science.gov (United States)

    Kuse, Yoshiki; Ogawa, Kenjiro; Tsuruma, Kazuhiro; Shimazawa, Masamitsu; Hara, Hideaki

    2014-06-09

    Our eyes are increasingly exposed to light from the emitting diode (LED) light of video display terminals (VDT) which contain much blue light. VDTs are equipped with televisions, personal computers, and smart phones. The present study aims to clarify the mechanism underlying blue LED light-induced photoreceptor cell damage. Murine cone photoreceptor-derived cells (661 W) were exposed to blue, white, or green LED light (0.38 mW/cm(2)). In the present study, blue LED light increased reactive oxygen species (ROS) production, altered the protein expression level, induced the aggregation of short-wavelength opsins (S-opsin), resulting in severe cell damage. While, blue LED light damaged the primary retinal cells and the damage was photoreceptor specific. N-Acetylcysteine (NAC), an antioxidant, protected against the cellular damage induced by blue LED light. Overall, the LED light induced cell damage was wavelength-, but not energy-dependent and may cause more severe retinal photoreceptor cell damage than the other LED light.

  5. Absorption and fluorescence spectroscopic characterisation of the circadian blue-light photoreceptor cryptochrome from Drosophila melanogaster (dCry)

    Science.gov (United States)

    Shirdel, J.; Zirak, P.; Penzkofer, A.; Breitkreuz, H.; Wolf, E.

    2008-09-01

    The absorption and fluorescence behaviour of the circadian blue-light photoreceptor cryptochrome from Drosophila melanogaster (dCry) in a pH 8 aqueous buffer solution is studied. The flavin adenine dinucleotide (FAD) cofactor of dCry is identified to be present in its oxidized form (FAD ox), and the 5,10-methenyltetrahydrofolate (MTHF) cofactor is found to be hydrolyzed and oxidized to 10-formyldihydrofolate (10-FDHF). The absorption and the fluorescence behaviour of dCry is investigated in the dark-adapted (receptor) state, the light-adapted (signalling) state, and under long-time violet light exposure. Photo-excitation of FAD ox in dCry causes a reductive electron transfer to the formation of anionic FAD semiquinone (FAD rad - ), and photo-excitation of the generated FAD rad - causes an oxidative electron transfer to the back formation of FAD ox. In light adapted dCry a photo-induced equilibrium between FAD ox and FAD rad - exists. The photo-cycle dynamics of signalling state formation and recovery is discussed. Quantum yields of photo-induced signalling state formation of about 0.2 and of photo-induced back-conversion of about 0.2 are determined. A recovery of FAD rad - to FAD ox in the dark with a time constant of 1.6 min at room temperature is found.

  6. The Phycomyces madA gene encodes a blue-light photoreceptor for phototropism and other light responses.

    Science.gov (United States)

    Idnurm, Alexander; Rodríguez-Romero, Julio; Corrochano, Luis M; Sanz, Catalina; Iturriaga, Enrique A; Eslava, Arturo P; Heitman, Joseph

    2006-03-21

    Phycomyces blakesleeanus is a filamentous zygomycete fungus that produces striking elongated single cells that extend up to 10 cm into the air, with each such sporangiophore supporting a sphere containing the spores for dispersal. This organism has served as a model for the detection of environmental signals as diverse as light, chemicals, touch, wind, gravity, and adjacent objects. In particular, sporangiophore growth is regulated by light, and it exhibits phototropism by bending toward near-UV and blue wavelengths and away from far-UV wavelengths in a manner that is physiologically similar to plant phototropic responses. The Phycomyces madA mutants were first isolated more than 40 years ago, and they exhibit reduced sensitivity to light. Here, we identify two (duplicated) homologs in the White Collar 1 family of blue-light photoreceptors in Phycomyces. We describe that the madA mutant strains contain point mutations in one of these genes and that these mutations cosegregate with a defect in phototropism after genetic crosses. Thus, the phototropic responses of fungi through madA and plants through phototropin rely on diverse proteins; however, these proteins share a conserved flavin-binding domain for photon detection.

  7. Chlamydomonas reinhardtii strain CC-124 is highly sensitive to blue light in addition to green and red light in resetting its circadian clock, with the blue-light photoreceptor plant cryptochrome likely acting as negative modulator.

    Science.gov (United States)

    Forbes-Stovall, Jennifer; Howton, Jonathan; Young, Matthew; Davis, Gavin; Chandler, Todd; Kessler, Bruce; Rinehart, Claire A; Jacobshagen, Sigrid

    2014-02-01

    The unicellular green alga Chlamydomonas reinhardtii has long served as model organism for studies on the circadian clock. This clock is present in all eukaryotes and some prokaryotes allowing them to anticipate and take advantage of the daily oscillations in the environment. Although much is known about the circadian clock in C. reinhardtii, the photoreceptors mediating entrainment of the clock to the daily changes of light remain obscure. Based on its circadian rhythm of phototaxis as a reporter of the clock's phase, we show here that C. reinhardtii strain CC-124 is highly sensitive to blue light of 440 nm when resetting its circadian clock upon light pulses. Thus, CC-124 differs in this respect from what was previously reported for a cell wall-deficient strain. An action spectrum analysis revealed that CC-124 also responds with high sensitivity to green (540 nm), red (640-660 nm), and possibly UV-A (≤400 nm) light, and therefore shows similarities as well to what has been reported for the cell wall-deficient strain. We also investigated two RNA interference strains with reductions in the level of the blue light photoreceptor plant cryptochrome (CPH1). One of them, the strain with the greater reduction, surprisingly showed an increased sensitivity in clock resetting upon blue light pulses of 440 nm. This increase in sensitivity reverted to wild-type levels when the RNA interference strain reverted to wild-type protein levels. It suggests that plant cryptochrome in C. reinhardtii could function as negative rather than positive modulator of circadian clock resetting. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  8. Establishment of a blue light damage model of human retinal pigment epithelial cells in vitro.

    Science.gov (United States)

    Su, G; Cai, S J; Gong, X; Wang, L L; Li, H H; Wang, L M

    2016-06-24

    To establish a blue-light damage model of human retinal pigment epithelium (RPE). Fourth-generation human RPE cells were randomly divided into two groups. In group A, cells were exposed to blue light (2000 ± 500 lux) for 0 (control), 3, 6, 9, and 12 h, and cell culture was stopped after 12 h. In group B, cells were exposed to blue light at the same intensity and time periods, but cell culture was stopped after 24 h. TdT-mediated dUTP nick-end labeling (TUNEL) assay was performed to determine the most suitable illuminating time with apoptotic index. Flow cytometry was used to determine apoptotic ratio of RPEs. In group A, the apoptotic index of cells that received 6, 9 and 12 h of blue light was higher than that of control. The apoptotic index of cells receiving 9 and 12 h was higher than that of 6 h (P = 0.000). In group B, the apoptotic index and RPE cell apoptosis ratio of cells exposed to 6, 9 and 12 h of blue light were higher than that of 3 h (P = 0.000); and cells receiving 9 and 12 h had higher values than that of 6 h. This study demonstrated that the best conditions to establish a blue light damage model of human retinal pigment epithelial cells in vitro are 2000 ± 500 lux light intensity for 6 h, with 24 h of cell culture post-exposure.

  9. Photoperiodic Responses and Characterization of the Cmvvd Gene Encoding a Blue Light Photoreceptor from the Medicinal Caterpillar Fungus Cordyceps militaris (Ascomycetes).

    Science.gov (United States)

    Zhang, Xin; Dong, Xiaoming; Song, Xinhua; Wang, Fen; Dong, Caihong

    2017-01-01

    Light is a necessary environmental factor for production of conidia and pigment, formation of stroma, and development of Cordyceps militaris, a well-known edible and medicinal mushroom. In this study, an obvious rhythm loop was observed in certain strains of C. militaris under conditions of alternating 12-hour intervals of dark and light. A possibly related gene, Cmvvd, the homologue of the blue-light photoreceptor of Neurospora crassa, was cloned from the genome of C. militaris. The protein CmVVD is predicted to be 203 amino acids in length and is characterized by the presence of a light, oxygen, or voltage domain. Analysis of the CmVVD sensor domain (light, oxygen, or voltage) suggested that it is a blue-light receptor. Cysteine 108 is essential for the in vivo function of VIVID (VVD) in N. crassa photoadaptation. However, proline is in this position instead in all of the tested CmVVD proteins, suggesting that CmVVD may have a different function or may function in ways different from VVD in N. crassa. Genetic variation analysis of CmVVD in 6 representative strains indicated that 3 informative sites exist. Cmvvd messenger RNA was able to be induced by light, and the expression level increased over 10 times after irradiation and was maintained at high levels in the nascent fruiting body. The light-induced expression of Cmvvd was abolished in Cmwc-1 mutants, suggesting that the expression of Cmvvd is dependent on the photoreceptor CmWC-1 or on a functional CmWC-1/WC-2 complex. This article will help to open the still-unexplored field of circadian rhythms for this fungus.

  10. Protective effects of bilberry and lingonberry extracts against blue light-emitting diode light-induced retinal photoreceptor cell damage in vitro.

    Science.gov (United States)

    Ogawa, Kenjirou; Kuse, Yoshiki; Tsuruma, Kazuhiro; Kobayashi, Saori; Shimazawa, Masamitsu; Hara, Hideaki

    2014-04-02

    Blue light is a high-energy or short-wavelength visible light, which induces retinal diseases such as age-related macular degeneration and retinitis pigmentosa. Bilberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea) contain high amounts of polyphenols (anthocyanins, resveratrol, and proanthocyanidins) and thus confer health benefits. This study aimed to determine the protective effects and mechanism of action of bilberry extract (B-ext) and lingonberry extract (L-ext) and their active components against blue light-emitting diode (LED) light-induced retinal photoreceptor cell damage. Cultured murine photoreceptor (661 W) cells were exposed to blue LED light following treatment with B-ext, L-ext, or their constituents (cyanidin, delphinidin, malvidin, trans-resveratrol, and procyanidin B2). 661 W cell viability was assessed using a tetrazolium salt (WST-8) assay and Hoechst 33342 nuclear staining, and intracellular reactive oxygen species (ROS) production was determined using CM-H2DCFDA after blue LED light exposure. Activation of p38 mitogen-activated protein kinase (p38 MAPK), nuclear factor-kappa B (NF-κB), and LC3, an ubiquitin-like protein that is necessary for the formation of autophagosomes, were analyzed using Western blotting. Caspase-3/7 activation caused by blue LED light exposure in 661 W cells was determined using a caspase-3/7 assay kit. B-ext, L-ext, NAC, and their active components improved the viability of 661 W cells and inhibited the generation of intracellular ROS induced by blue LED light irradiation. Furthermore, B-ext and L-ext inhibited the activation of p38 MAPK and NF-κB induced by blue LED light exposure. Finally, B-ext, L-ext, and NAC inhibited caspase-3/7 activation and autophagy. These findings suggest that B-ext and L-ext containing high amounts of polyphenols exert protective effects against blue LED light-induced retinal photoreceptor cell damage mainly through inhibition of ROS production and activation of

  11. Photodynamics of blue-light-regulated phosphodiesterase BlrP1 protein from Klebsiella pneumoniae and its photoreceptor BLUF domain

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, A. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany); Penzkofer, A. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany)], E-mail: alfons.penzkofer@physik.uni-regensburg.de; Griese, J.; Schlichting, I. [Max-Planck-Institut fuer medizinische Forschung, Abteilung Biomolekulare Mechanismen, Jahnstrasse 29, D-69120 Heidelberg (Germany); Kirienko, Natalia V.; Gomelsky, Mark [Department of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071 (United States)

    2008-12-10

    The BlrP1 protein from the enteric bacterium Klebsiella pneumoniae consists of a BLUF and an EAL domain and may activate c-di-GMP phosphodiesterase by blue-light. The full-length protein, BlrP1, and its BLUF domain, BlrP1{sub B}LUF, are characterized by optical absorption and emission spectroscopy. The cofactor FAD in its oxidized redox state (FAD{sub ox}) is brought from the dark-adapted receptor state to the 10-nm red-shifted putative signalling state by violet light exposure. The recovery to the receptor state occurs with a time constant of about 1 min. The quantum yield of signalling state formation is about 0.17 for BlrP1{sub B}LUF and about 0.08 for BlrP1. The fluorescence efficiency of the FAD{sub ox} cofactor is small due to photo-induced reductive electron transfer. Prolonged light exposure converts FAD{sub ox} in the signalling state to the fully reduced hydroquinone form FAD{sub red}H{sup -} and causes low-efficient chromophore release with subsequent photo-degradation. The photo-cycle and photo-reduction dynamics in the receptor state and in the signalling state are discussed.

  12. Photodynamics of blue-light-regulated phosphodiesterase BlrP1 protein from Klebsiella pneumoniae and its photoreceptor BLUF domain

    Science.gov (United States)

    Tyagi, A.; Penzkofer, A.; Griese, J.; Schlichting, I.; Kirienko, Natalia V.; Gomelsky, Mark

    2008-12-01

    The BlrP1 protein from the enteric bacterium Klebsiella pneumoniae consists of a BLUF and an EAL domain and may activate c-di-GMP phosphodiesterase by blue-light. The full-length protein, BlrP1, and its BLUF domain, BlrP1_BLUF, are characterized by optical absorption and emission spectroscopy. The cofactor FAD in its oxidized redox state (FAD ox) is brought from the dark-adapted receptor state to the 10-nm red-shifted putative signalling state by violet light exposure. The recovery to the receptor state occurs with a time constant of about 1 min. The quantum yield of signalling state formation is about 0.17 for BlrP1_BLUF and about 0.08 for BlrP1. The fluorescence efficiency of the FAD ox cofactor is small due to photo-induced reductive electron transfer. Prolonged light exposure converts FAD ox in the signalling state to the fully reduced hydroquinone form FAD redH - and causes low-efficient chromophore release with subsequent photo-degradation. The photo-cycle and photo-reduction dynamics in the receptor state and in the signalling state are discussed.

  13. Indirect blue light does not suppress nocturnal salivary melatonin in humans in an automobile setting.

    Science.gov (United States)

    Lerchl, Alexander; Schindler, Carina; Eichhorn, Karsten; Kley, Franziska; Erren, Thomas C

    2009-09-01

    In 2007, the International Agency for Research on Cancer (IARC) classified shift work that involves circadian disruption as being probably carcinogenic to humans (Group 2A). In this context, light exposure during the night plays a key role because it can suppress nocturnal melatonin levels when exposures exceed a certain threshold. Blue light around 464 nm is most effective in suppressing melatonin because of the spectral sensitivity of melanopsin, a recently discovered photopigment in retinal ganglion cells; the axons of these cells project to the suprachiasmatic nucleus, a circadian master clock in the brain. Due to advances in light technologies, normal tungsten light bulbs are being replaced by light-emitting diodes which produce quasi-monochromatic or white light. The objective of this study was to assess whether the light-melanopsin-melatonin axis might be affected in automobiles at night which employ the new generation diodes. To this end, we have tested in an experimental automobile setting whether indirect blue light (lambda(max) = 465 nm) at an intensity of 0.22 or 1.25 lx can suppress salivary melatonin levels in 12 male volunteers (age range 17-27 years) who served as their own controls. Daytime levels were low (2.7 +/- 0.5 pg/mL), and night-time levels without light exposure were high (14.5 +/- 1.1 pg/mL), as expected. Low-intensity light exposures had no significant effect on melatonin levels (0.22 lx: 17.2 +/- 2.8 pg/mL; P > 0.05; 1.25 lx: 12.6 +/- 2.0 pg/mL; P > 0.05). It is concluded that indirect blue light exposures in automobiles up to 1.25 lx do not cause unintentional chronodisruption via melatonin suppression.

  14. Human Lens Transmission of Blue Light: A Comparison of Autofluorescence-Based and Direct Spectral Transmission Determination

    DEFF Research Database (Denmark)

    Broendsted, Adam Elias; Stormly Hansen, Michael; Lund-Andersen, Henrik

    2011-01-01

    Purpose: Direct measurement of the transmission of light through the human lens is not possible in vivo unless invasive techniques are used. In the current study, a reliable in vivo estimate of the transmission of blue light through the lens was assessed by comparing an indirect and noninvasive...... method based on autofluorescence measurements with a direct method. Methods: Total transmission of blue light was measured in human donor lenses using a direct method applicable only in vitro and compared with transmittance estimates made by an in vivo applicable autofluorescence technique. Results......: Human lens transmission of blue light decreases with age by 0.7-0.8% per year at 480 nm. The comparison of methods showed that the autofluorescence-based method correlated significantly with the direct measurements (R = 0.83, p

  15. A comparison of blue light and caffeine effects on cognitive function and alertness in humans.

    Directory of Open Access Journals (Sweden)

    C Martyn Beaven

    Full Text Available The alerting effects of both caffeine and short wavelength (blue light have been consistently reported. The ability of blue light to enhance alertness and cognitive function via non-image forming neuropathways have been suggested as a non-pharmacological countermeasure for drowsiness across a range of occupational settings. Here we compare and contrast the alerting and psychomotor effects of 240 mg of caffeine and a 1-h dose of ~40 lx blue light in a non-athletic population. Twenty-one healthy subjects performed a computer-based psychomotor vigilance test before and after each of four randomly assigned trial conditions performed on different days: white light/placebo; white light/240 mg caffeine; blue light/placebo; blue light/240 mg caffeine. The Karolinska Sleepiness Scale was used to assess subjective measures of alertness. Both the caffeine only and blue light only conditions enhanced accuracy in a visual reaction test requiring a decision and an additive effect was observed with respect to the fastest reaction times. However, in a test of executive function, where a distraction was included, caffeine exerted a negative effect on accuracy. Furthermore, the blue light only condition consistently outperformed caffeine when both congruent and incongruent distractions were presented. The visual reactions in the absence of a decision or distraction were also enhanced in the blue light only condition and this effect was most prominent in the blue-eyed participants. Overall, blue light and caffeine demonstrated distinct effects on aspects of psychomotor function and have the potential to positively influence a range of settings where cognitive function and alertness are important. Specifically, despite the widespread use of caffeine in competitive sporting environments, the possible impact of blue light has received no research attention.

  16. A comparison of blue light and caffeine effects on cognitive function and alertness in humans.

    Science.gov (United States)

    Beaven, C Martyn; Ekström, Johan

    2013-01-01

    The alerting effects of both caffeine and short wavelength (blue) light have been consistently reported. The ability of blue light to enhance alertness and cognitive function via non-image forming neuropathways have been suggested as a non-pharmacological countermeasure for drowsiness across a range of occupational settings. Here we compare and contrast the alerting and psychomotor effects of 240 mg of caffeine and a 1-h dose of ~40 lx blue light in a non-athletic population. Twenty-one healthy subjects performed a computer-based psychomotor vigilance test before and after each of four randomly assigned trial conditions performed on different days: white light/placebo; white light/240 mg caffeine; blue light/placebo; blue light/240 mg caffeine. The Karolinska Sleepiness Scale was used to assess subjective measures of alertness. Both the caffeine only and blue light only conditions enhanced accuracy in a visual reaction test requiring a decision and an additive effect was observed with respect to the fastest reaction times. However, in a test of executive function, where a distraction was included, caffeine exerted a negative effect on accuracy. Furthermore, the blue light only condition consistently outperformed caffeine when both congruent and incongruent distractions were presented. The visual reactions in the absence of a decision or distraction were also enhanced in the blue light only condition and this effect was most prominent in the blue-eyed participants. Overall, blue light and caffeine demonstrated distinct effects on aspects of psychomotor function and have the potential to positively influence a range of settings where cognitive function and alertness are important. Specifically, despite the widespread use of caffeine in competitive sporting environments, the possible impact of blue light has received no research attention.

  17. Brain responses to violet, blue, and green monochromatic light exposures in humans: prominent role of blue light and the brainstem.

    Directory of Open Access Journals (Sweden)

    Gilles Vandewalle

    Full Text Available BACKGROUND: Relatively long duration retinal light exposure elicits nonvisual responses in humans, including modulation of alertness and cognition. These responses are thought to be mediated in part by melanopsin-expressing retinal ganglion cells which are more sensitive to blue light than violet or green light. The contribution of the melanopsin system and the brain mechanisms involved in the establishment of such responses to light remain to be established. METHODOLOGY/PRINCIPAL FINDINGS: We exposed 15 participants to short duration (50 s monochromatic violet (430 nm, blue (473 nm, and green (527 nm light exposures of equal photon flux (10(13ph/cm(2/s while they were performing a working memory task in fMRI. At light onset, blue light, as compared to green light, increased activity in the left hippocampus, left thalamus, and right amygdala. During the task, blue light, as compared to violet light, increased activity in the left middle frontal gyrus, left thalamus and a bilateral area of the brainstem consistent with activation of the locus coeruleus. CONCLUSION/SIGNIFICANCE: These results support a prominent contribution of melanopsin-expressing retinal ganglion cells to brain responses to light within the very first seconds of an exposure. The results also demonstrate the implication of the brainstem in mediating these responses in humans and speak for a broad involvement of light in the regulation of brain function.

  18. PHH1, a novel gene from Arabidopsis thaliana that encodes a protein similar to plant blue-light photoreceptors and microbial photolyases.

    Science.gov (United States)

    Hoffman, P D; Batschauer, A; Hays, J B

    1996-11-27

    A cDNA from Arabidopsis thaliana similar to microbial photolyase genes, and designated AT-PHH1, was isolated using a photolyase-like cDNA from Sinapsis alba (SA-PHR1) as a probe. Multiple isolations yielded only PHH1 cDNAs, and a few blue-light-receptor CRY1 (HY4) cDNAs (also similar to microbial photolyase genes), suggesting the absence of any other highly similar Arabidopsis genes. The AT-PHH1 and SA-PHR1 cDNA sequences predict 89% identity at the protein level, except for an AT-PHH1 C-terminal extension (111 amino acids), also not seen in microbial photolyases. AT-PHH1 and CRY1 show less similarity (54% p4erein identity), including respective C-terminal extensions that are themselves mostly dissimilar. Analysis of fifteen AT-PHH1 genomic isolates reveals a single gene, with three introns in the coding sequence and one in the 5'-untranslated leader. Full-length AT-PHH1, and both AT-PHH1 and AT-PHH1 delta C-513 (truncated to be approximately the size of microbial photolyase genes) cDNAs, were overexpressed, respectively, in yeast and Escherichia coli mutants hypersensitive to ultraviolet light. The absence of significant effects on resistance suggests either that any putative AT-PHH1 DNA repair activity requires cofactors/chromophores not present in yeast or E. coli, or that AT-PHH1 encodes a blue-light/ultraviolet-A receptor rather than a DNA repair protein.

  19. Combatant Eye Protection: An Introduction to the Blue Light Hazard

    Science.gov (United States)

    2015-12-01

    energy distribution curves are becoming increasingly relevant to our daily lives, as a result of their use in mobile phones, modern televisions ...input for various nonvisual 7 behavior and physiological functions. The nonvisual photoreceptor melanopsin absorbs blue light and triggers the...Sekharan, Wei, and Batista, 2012; Berson, Dunn, and Takao, 2002; Wolf, 2002). Consequently, it is possible that blue light filters may disrupt sleep

  20. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder

    NARCIS (Netherlands)

    Meesters, Ybe; Winthorst, Wim H.; Duijzer, Wianne; Bos, Elisabeth; V, Hommes,

    2016-01-01

    Background The discovery of a novel photoreceptor in the retinal ganglion cells with a highest sensitivity of 470-490 nm blue light has led to research on the effects of short-wavelength light in humans. Several studies have explored the efficacy of monochromatic blue or blue-enriched light in the

  1. A train of blue light pulses delivered through closed eyelids suppresses melatonin and phase shifts the human circadian system

    Directory of Open Access Journals (Sweden)

    Figueiro MG

    2013-10-01

    basic understanding of circadian phototransduction and broaden the technical foundations for delivering light through closed eyelids during sleep for treating circadian sleep disorders.Keywords: melatonin, dim light melatonin onset, eyelids, flashing blue light, circadian rhythms, sleep

  2. Visual transduction in human rod photoreceptors.

    Science.gov (United States)

    Kraft, T W; Schneeweis, D M; Schnapf, J L

    1993-05-01

    1. Photocurrents were recorded with suction electrodes from rod photoreceptors of seven humans. 2. Brief flashes of light evoked transient outward currents of up to 20 pA. With increasing light intensity the peak response amplitude increased along an exponential saturation function. A half-saturating peak response was evoked by approximately sixty-five photoisomerizations. 3. Responses to brief dim flashes rose to a peak in about 200 ms. The waveform was roughly like the impulse response of a series of four to five low-pass filters. 4. The rising phases of the responses to flashes of increasing strength were found to fit with a biochemical model of phototransduction with an 'effective delay time' and 'characteristic time' of about 2 and 800 ms, respectively. 5. Spectral sensitivities were obtained over a wavelength range from 380 to 760 nm. The action spectrum, which peaked at 495 nm, followed the template described for photoreceptors in the macaque retina. Variation between rods in the position of the spectrum on the wavelength axis was small. 6. The scotopic luminosity function derived from human psychophysical experiments was found to agree well with the measured rod action spectrum after adjustments were made for lens absorption and photopigment self-screening in the intact eye. 7. Responses to steps of light rose monotonically to a maintained level, showing little or no relaxation. Nevertheless, the relationship between light intensity and steady-state response amplitude was shallower than that expected from simple response saturation. This is consistent with an adaptation mechanism acting on a rapid time scale. 8. Flash sensitivity fell with increasing intensities of background light according to Weber's law. Sensitivity was reduced twofold by lights evoking about 120 photoisomerizations per second. Background lights decreased the time to peak and the integration time of the flash response by up to 20%.

  3. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder

    OpenAIRE

    Meesters, Ybe; Winthorst, Wim H; Duijzer, Wianne B.; Hommes, Vanja

    2016-01-01

    Background The discovery of a novel photoreceptor in the retinal ganglion cells with a highest sensitivity of 470-490 nm blue light has led to research on the effects of short-wavelength light in humans. Several studies have explored the efficacy of monochromatic blue or blue-enriched light in the treatment of SAD. In this study, a comparison has been made between the effects of broad-wavelength light without ultraviolet (UV) wavelengths compared to narrow-band blue light in the treatment of ...

  4. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder

    OpenAIRE

    Meesters, Ybe; Winthorst, Wim H; Duijzer, Wianne; Bos, Elisabeth; V, Hommes,

    2016-01-01

    Background The discovery of a novel photoreceptor in the retinal ganglion cells with a highest sensitivity of 470-490 nm blue light has led to research on the effects of short-wavelength light in humans. Several studies have explored the efficacy of monochromatic blue or blue-enriched light in the treatment of SAD. In this study, a comparison has been made between the effects of broad-wavelength light without ultraviolet (UV) wavelengths compared to narrow-band blue light in the treatment of ...

  5. [The dangers of blue light: True story!].

    Science.gov (United States)

    Renard, G; Leid, J

    2016-05-01

    The dangers of the blue light are the object of numerous publications, for both the scientific community and the general public. The new prolific development of light sources emitting potentially toxic blue light (415-455nm) ranges from LED (Light Emitting Diodes) lamps for interior lighting to television screens, computers, digital tablets and smartphones using OLED (Organic Light Emitting Diode) or AMOLED (Active-Matrix Organic Light Emitting Diode) technology. First we will review some technical terms and the main characteristics of light perceived by the human eye. Then we will discuss scientific proof of the toxicity of blue light to the eye, which may cause cataract or macular degeneration. Analysis of the light spectra of several light sources, from natural light to LED lamps, will allow us to specify even better the dangers related to each light source. LED lamps, whether used as components for interior lighting or screens, are of concern if they are used for extended viewing times and at short distance. While we can protect ourselves from natural blue light by wearing colored glasses which filter out, on both front and back surfaces, the toxic wavelengths, it is more difficult to protect oneself from LED lamps in internal lighting, the use of which should be restricted to "white warmth" lamps (2700K). As far as OLED or AMOLED screens are concerned, the only effective protection consists of using them occasionally and only for a short period of time. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  6. Blue light inhibits proliferation of melanoma cells

    Science.gov (United States)

    Becker, Anja; Distler, Elisabeth; Klapczynski, Anna; Arpino, Fabiola; Kuch, Natalia; Simon-Keller, Katja; Sticht, Carsten; van Abeelen, Frank A.; Gretz, Norbert; Oversluizen, Gerrit

    2016-03-01

    Photobiomodulation with blue light is used for several treatment paradigms such as neonatal jaundice, psoriasis and back pain. However, little is known about possible side effects concerning melanoma cells in the skin. The aim of this study was to assess the safety of blue LED irradiation with respect to proliferation of melanoma cells. For that purpose we used the human malignant melanoma cell line SK-MEL28. Cell proliferation was decreased in blue light irradiated cells where the effect size depended on light irradiation dosage. Furthermore, with a repeated irradiation of the melanoma cells on two consecutive days the effect could be intensified. Fluorescence-activated cell sorting with Annexin V and Propidium iodide labeling did not show a higher number of dead cells after blue light irradiation compared to non-irradiated cells. Gene expression analysis revealed down-regulated genes in pathways connected to anti-inflammatory response, like B cell signaling and phagosome. Most prominent pathways with up-regulation of genes were cytochrome P450, steroid hormone biosynthesis. Furthermore, even though cells showed a decrease in proliferation, genes connected to the cell cycle were up-regulated after 24h. This result is concordant with XTT test 48h after irradiation, where irradiated cells showed the same proliferation as the no light negative control. In summary, proliferation of melanoma cells can be decreased using blue light irradiation. Nevertheless, the gene expression analysis has to be further evaluated and more studies, such as in-vivo experiments, are warranted to further assess the safety of blue light treatment.

  7. Phototropins and chloroplast activity in plant blue light signaling

    OpenAIRE

    Goh, Chang-Hyo

    2009-01-01

    In plants, phototropins 1 (phot1) and 2 (phot2) mediate chloroplast movement to blue light (BL). A recent report showed that phototropins (phot) are required for the expression of chloroplast genes in rice. The light-induced responses of phot1a rice mutants result in H2O2-mediated damage to chloroplast photosystems, indicating that phot-regulated responses might be associated with the other photoreceptor, such as cryptochrome (cry) BL receptor. This suggests diversification and specialization...

  8. From Plant Infectivity to Growth Patterns: The Role of Blue-Light Sensing in the Prokaryotic World

    Directory of Open Access Journals (Sweden)

    Aba Losi

    2014-01-01

    Full Text Available Flavin-based photoreceptor proteins of the LOV (Light, Oxygen, and Voltage and BLUF (Blue Light sensing Using Flavins superfamilies are ubiquitous among the three life domains and are essential blue-light sensing systems, not only in plants and algae, but also in prokaryotes. Here we review their biological roles in the prokaryotic world and their evolution pathways. An unexpected large number of bacterial species possess flavin-based photosensors, amongst which are important human and plant pathogens. Still, few cases are reported where the activity of blue-light sensors could be correlated to infectivity and/or has been shown to be involved in the activation of specific genes, resulting in selective growth patterns. Metagenomics and bio-informatic analysis have only recently been initiated, but signatures are beginning to emerge that allow definition of a bona fide LOV or BLUF domain, aiming at better selection criteria for novel blue-light sensors. We also present here, for the first time, the phylogenetic tree for archaeal LOV domains that have reached a statistically significant number but have not at all been investigated thus far.

  9. Human neural progenitor cells promote photoreceptor survival in retinal explants.

    Science.gov (United States)

    Englund-Johansson, Ulrica; Mohlin, Camilla; Liljekvist-Soltic, Ingela; Ekström, Per; Johansson, Kjell

    2010-02-01

    Different types of progenitor and stem cells have been shown to provide neuroprotection in animal models of photoreceptor degeneration. The present study was conducted to investigate whether human neural progenitor cells (HNPCs) have neuroprotective properties on retinal explants models with calpain- and caspase-3-dependent photoreceptor cell death. In the first experiments, HNPCs in a feeder layer were co-cultured for 6 days either with postnatal rd1 mouse or normal rat retinas. Retinal histological sections were used to determine outer nuclear layer (ONL) thickness, and to detect the number of photoreceptors with labeling for calpain activity, cleaved caspase-3 and TUNEL. The ONL thickness of co-cultured rat and rd1 retinas was found to be almost 10% and 40% thicker, respectively, compared to controls. Cell counts of calpain activity, cleaved caspase-3 and TUNEL labeled photoreceptors in both models revealed a 30-50% decrease when co-cultured with HNPCs. The results represent significant increases of photoreceptor survival in the co-cultured retinas. In the second experiments, for an identification of putative survival factors, or a combination of them, a growth factor profile was performed on conditioned medium. The relative levels of various growth factors were analyzed by densitometric measurements of growth factor array membranes. Following growth factors were identified as most potential survival factors; granulocyte colony stimulating factor (G-CSF), granulocyte-macrophage colony stimulating factor (GMCSF), insulin-like growth factor II (IGF-II), neurotrophic factor 3 (NT-3), placental growth factor (PIGF), transforming growth factors (TGF-beta1 and TGF-beta2) and vascular endothelial growth factor (VEGF-D). HNPCs protect both against calpain- and caspase-3-dependent photoreceptor cell death in the rd1 mouse and against caspase-3-dependent photoreceptor cell death in normal rat retinas in vitro. The protective effect is possibly achieved by a variety of

  10. Anti-apoptotic effects of Curcuma longa L. extract and its curcuminoids against blue light-induced cytotoxicity in A2E-laden human retinal pigment epithelial cells.

    Science.gov (United States)

    Park, Sang-Il; Lee, Eun Hye; Kim, So Ra; Jang, Young Pyo

    2017-03-01

    The purpose of the study was to investigate the protective effect of the Curcuma longa L. extract (CLE) and its curcuminoids against blue light-induced cytotoxicity in human retinal pigment epithelial (RPE) cells laded with A2E. A2E has been concerned in age-related macular degeneration (AMD). To perform this study, A2E-accumulated ARPE-19 cells were exposed to blue light to induce cytotoxicity. The cytotoxicity and apoptotic gene expression levels were evaluated using a lactate dehydrogenase (LDH) assay and real-time PCR analysis, respectively. Curcuma longa L. extract was found to exert a protective effect in a dose-dependent manner. At a concentration of 15 μm, curcumin, demethoxycurcumin and bisdemethoxycurcumin exerted significant protective effects against blue light-induced cytotoxicity. Treatment with CLE and curcuminoids meaningfully reduced the mRNA levels of c-Abl and p53, which was known to be augmented in apoptotic RPE cells. Demethoxycurcumin and bisdemethoxycurcumin were found to inhibit p38 expression, which is increased in blue light-irradiated A2E-accumulated RPE cells. Curcuma longa L. extract and its curcuminoids provided significant protection against photooxidative damage and apoptosis in the RPE cells. Our results suggest that curcuminoids may show potential in the treatment of AMD. © 2017 Royal Pharmaceutical Society.

  11. Antimicrobial blue light therapy for Candida albicans burn infection in mice

    Science.gov (United States)

    Zhang, Yunsong; Wang, Yucheng; Murray, Clinton K.; Hamblin, Michael R.; Gu, Ying; Dai, Tianhong

    2015-05-01

    In this preclinical study, we investigated the utility of antimicrobial blue light therapy for Candida albicans infection in acutely burned mice. A bioluminescent strain of C. albicans was used. The susceptibilities to blue light inactivation were compared between C. albicans and human keratinocyte. In vitro serial passaging of C. albicans on blue light exposure was performed to evaluate the potential development of resistance to blue light inactivation. A mouse model of acute thermal burn injury infected with the bioluminescent strain of C. albicans was developed. Blue light (415 nm) was delivered to mouse burns for decolonization of C. albicans. Bioluminescence imaging was used to monitor in real time the extent of fungal infection in mouse burns. Experimental results showed that C. albicans was approximately 42-fold more susceptible to blue light inactivation in vitro than human keratinocyte (P=0.0022). Serial passaging of C. albicans on blue light exposure implied a tendency for the fungal susceptibility to blue light inactivation to decrease with the numbers of passages. Blue light reduced fungal burden by over 4-log10 (99.99%) in acute mouse burns infected with C. albicans in comparison to infected mouse burns without blue light therapy (P=0.015).

  12. UV-A/Blue-Light responses in algae

    Science.gov (United States)

    Senger, Horst; Hermsmeier, Dieter

    1994-01-01

    All life on earth depends on light. A variety of photoreceptors capture the light for a wide range of reactions. Photosynthetic organisms absorb the light necessary for energy transformation and charge separation facilitating photosynthesis. In addition to the bulk pigments there is a great diversity of photoreceptors present in minute concentrations that control development, metabolism and orientation of plants and microorganisms. Based on its spectral absorbance, the well-studied phytochrome system acts in the RL (red light) region as well as in the UV-A/BL (blue light) region where the above mentioned reactions are mediated by a variety of photoreceptors whose natures are largely unknown. Phyllogenetically the UV-A/BL photoreceptors seem to be more ancient pigments that eventually were replaced by the phytochrome system. However, there are many reports that suggest a coaction between the UV-A/BL receptors and the phytochrome system. In several cases the UV-A/BL activation is the prerequisite for the phytochrome reaction. Historically it was the German botanist Julius Sachs who first discovered in 1864 that phototropism in plants was due to BL reactions. It took over 70 years until Bunning (1937) and Galston and Baker (1949) rediscovered the BL response. Since then, an ever-increasing attention has been paid to this effect. In this contribution, the general aspect of UV-A/BL responses and especially the responsiveness of algae will be covered.

  13. Transcriptome sequencing and comparative analysis of Saccharina japonica (Laminariales, Phaeophyceae under blue light induction.

    Directory of Open Access Journals (Sweden)

    Yunyan Deng

    Full Text Available BACKGROUND: Light has significant effect on the growth and development of Saccharina japonica, but there are limited reports on blue light mediated physiological responses and molecular mechanism. In this study, high-throughput paired-end RNA-sequencing (RNA-Seq technology was applied to transcriptomes of S. japonica exposed to blue light and darkness, respectively. Comparative analysis of gene expression was designed to correlate the effect of blue light and physiological mechanisms on the molecular level. PRINCIPAL FINDINGS: RNA-seq analysis yielded 70,497 non-redundant unigenes with an average length of 538 bp. 28,358 (40.2% functional transcripts encoding regions were identified. Annotation through Swissprot, Nr, GO, KEGG, and COG databases showed 25,924 unigenes compared well (E-value <10(-5 with known gene sequences, and 43 unigenes were putative BL photoreceptor. 10,440 unigenes were classified into Gene Ontology, and 8,476 unigenes were involved in 114 known pathways. Based on RPKM values, 11,660 (16.5% differentially expressed unigenes were detected between blue light and dark exposed treatments, including 7,808 upregulated and 3,852 downregulated unigenes, suggesting S. japonica had undergone extensive transcriptome re-orchestration during BL exposure. The BL-specific responsive genes were indentified to function in processes of circadian rhythm, flavonoid biosynthesis, photoreactivation and photomorphogenesis. SIGNIFICANCE: Transcriptome profiling of S. japonica provides clues to potential genes identification and future functional genomics study. The global survey of expression changes under blue light will enhance our understanding of molecular mechanisms underlying blue light induced responses in lower plants as well as facilitate future blue light photoreceptor identification and specific responsive pathways analysis.

  14. Identifying photoreceptors in blind eyes caused by RPE65 mutations: Prerequisite for human gene therapy success.

    Science.gov (United States)

    Jacobson, Samuel G; Aleman, Tomas S; Cideciyan, Artur V; Sumaroka, Alexander; Schwartz, Sharon B; Windsor, Elizabeth A M; Traboulsi, Elias I; Heon, Elise; Pittler, Steven J; Milam, Ann H; Maguire, Albert M; Palczewski, Krzysztof; Stone, Edwin M; Bennett, Jean

    2005-04-26

    Mutations in RPE65, a gene essential to normal operation of the visual (retinoid) cycle, cause the childhood blindness known as Leber congenital amaurosis (LCA). Retinal gene therapy restores vision to blind canine and murine models of LCA. Gene therapy in blind humans with LCA from RPE65 mutations may also have potential for success but only if the retinal photoreceptor layer is intact, as in the early-disease stage-treated animals. Here, we use high-resolution in vivo microscopy to quantify photoreceptor layer thickness in the human disease to define the relationship of retinal structure to vision and determine the potential for gene therapy success. The normally cone photoreceptor-rich central retina and rod-rich regions were studied. Despite severely reduced cone vision, many RPE65-mutant retinas had near-normal central microstructure. Absent rod vision was associated with a detectable but thinned photoreceptor layer. We asked whether abnormally thinned RPE65-mutant retina with photoreceptor loss would respond to treatment. Gene therapy in Rpe65(-/-) mice at advanced-disease stages, a more faithful mimic of the humans we studied, showed success but only in animals with better-preserved photoreceptor structure. The results indicate that identifying and then targeting retinal locations with retained photoreceptors will be a prerequisite for successful gene therapy in humans with RPE65 mutations and in other retinal degenerative disorders now moving from proof-of-concept studies toward clinical trials.

  15. Generation, purification and transplantation of photoreceptors derived from human induced pluripotent stem cells.

    Directory of Open Access Journals (Sweden)

    Deepak A Lamba

    Full Text Available BACKGROUND: Inherited and acquired retinal degenerations are frequent causes of visual impairment and photoreceptor cell replacement therapy may restore visual function to these individuals. To provide a source of new retinal neurons for cell based therapies, we developed methods to derive retinal progenitors from human ES cells. METHODOLOGY/PHYSICAL FINDINGS: In this report we have used a similar method to direct induced pluripotent stem cells (iPS from human fibroblasts to a retinal progenitor fate, competent to generate photoreceptors. We also found we could purify the photoreceptors derived from the iPS cells using fluorescence activated cell sorting (FACS after labeling photoreceptors with a lentivirus driving GFP from the IRBP cis-regulatory sequences. Moreover, we found that when we transplanted the FACS purified iPSC derived photoreceptors, they were able to integrate into a normal mouse retina and express photoreceptor markers. CONCLUSIONS: This report provides evidence that enriched populations of human photoreceptors can be derived from iPS cells.

  16. The effect of blue light exposure in an ocular melanoma animal model

    Directory of Open Access Journals (Sweden)

    Odashiro Alexandre N

    2009-04-01

    Full Text Available Abstract Background Uveal melanoma (UM cell lines, when exposed to blue light in vitro, show a significant increase in proliferation. In order to determine if similar effects could be seen in vivo, we investigated the effect of blue light exposure in a xenograft animal model of UM. Methods Twenty New Zealand albino rabbits were injected with 1.0 × 106 human UM cells (92.1 in the suprachoroidal space of the right eye. Animals were equally divided into two groups; the experimental group was exposed to blue light, while the control group was protected from blue light exposure. The eyes were enucleated after sacrifice and the proliferation rates of the re-cultured tumor cells were assessed using a Sulforhodamine-B assay. Cells were re-cultured for 1 passage only in order to maintain any in vivo cellular changes. Furthermore, Proliferating Cell Nuclear Antigen (PCNA protein expression was used to ascertain differences in cellular proliferation between both groups in formalin-fixed, paraffin-embedded eyes (FFPE. Results Blue light exposure led to a statistically significant increase in proliferation for cell lines derived from intraocular tumors (p Conclusion There is an increasing amount of data suggesting that blue light exposure may influence the progression of UM. Our results support this notion and warrant further studies to evaluate the ability of blue light filtering lenses to slow disease progression in UM patients.

  17. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder.

    Science.gov (United States)

    Meesters, Ybe; Winthorst, Wim H; Duijzer, Wianne B; Hommes, Vanja

    2016-02-18

    The discovery of a novel photoreceptor in the retinal ganglion cells with a highest sensitivity of 470-490 nm blue light has led to research on the effects of short-wavelength light in humans. Several studies have explored the efficacy of monochromatic blue or blue-enriched light in the treatment of SAD. In this study, a comparison has been made between the effects of broad-wavelength light without ultraviolet (UV) wavelengths compared to narrow-band blue light in the treatment of sub-syndromal seasonal affective disorder (Sub-SAD). In a 15-day design, 48 participants suffering from Sub-SAD completed 20-minute sessions of light treatment on five consecutive days. 22 participants were given bright white-light treatment (BLT, broad-wavelength light without UV 10 000 lux, irradiance 31.7 Watt/m(2)) and 26 participants received narrow-band blue light (BLUE, 100 lux, irradiance 1.0 Watt/m(2)). All participants completed daily and weekly questionnaires concerning mood, activation, sleep quality, sleepiness and energy. Also, mood and energy levels were assessed by means of the SIGH-SAD, the primary outcome measure. On day 15, SIGH-SAD ratings were significantly lower than on day 1 (BLT 54.8 %, effect size 1.7 and BLUE 50.7 %, effect size 1.9). No statistically significant differences were found on the main outcome measures. Light treatment is an effective treatment for Sub-SAD. The use of narrow-band blue-light treatment is equally effective as bright white-light treatment. This study was registered in the Dutch Trial Register (Nederlands Trial Register TC =  4342 ) (20-12-2013).

  18. Cellular detection of 50 Hz magnetic fields and weak blue light: effects on superoxide levels and genotoxicity.

    Science.gov (United States)

    Höytö, Anne; Herrala, Mikko; Luukkonen, Jukka; Juutilainen, Jukka; Naarala, Jonne

    2017-06-01

    We tested the hypothesis that the effects of 50 Hz magnetic fields (MFs) on superoxide levels and genotoxicity depend on the presence of blue light. Human SH-SY5Y neuroblastoma cells were exposed to a 50 Hz, 100 μT MF with or without non-phototoxic level of blue light for 24 h. We also studied whether these treatments alter responses to menadione, an agent that induces mitochondrial superoxide (O2(• -)) production and DNA damage. Micronuclei, proliferation, viability, cytosolic and mitochondrial O2(• -) levels were assessed. MF (without blue light) increased cytosolic O2(• -) production and blue light suppressed this effect. Mitochondrial O2(• -) production was reduced by both MF and blue light, but these effects were not additive. Micronucleus frequency was not affected by blue light or MF alone, but blue light (significantly when combined with MF) enhanced menadione-induced micronuclei. The original simple hypothesis (blue light is needed for MF effects) was not supported, but interaction of MF and blue light was nevertheless observed. The results are consistent with MF effects on light-independent radical reactions.

  19. HFR1 is crucial for transcriptome regulation in the cryptochrome 1-mediated early response to blue light in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Xiao-Ning Zhang

    Full Text Available Cryptochromes are blue light photoreceptors involved in development and circadian clock regulation. They are found in both eukaryotes and prokaryotes as light sensors. Long Hypocotyl in Far-Red 1 (HFR1 has been identified as a positive regulator and a possible transcription factor in both blue and far-red light signaling in plants. However, the gene targets that are regulated by HFR1 in cryptochrome 1 (cry1-mediated blue light signaling have not been globally addressed. We examined the transcriptome profiles in a cry1- and HFR1-dependent manner in response to 1 hour of blue light. Strikingly, more than 70% of the genes induced by blue light in an HFR1-dependent manner were dependent on cry1, and vice versa. High overrepresentation of W-boxes and OCS elements were found in these genes, indicating that this strong cry1 and HFR1 co-regulation on gene expression is possibly through these two cis-elements. We also found that cry1 was required for maintaining the HFR1 protein level in blue light, and that the HFR1 protein level is strongly correlated with the global gene expression pattern. In summary, HFR1, which is fine-tuned by cry1, is crucial for regulating global gene expression in cry1-mediated early blue light signaling, especially for the function of genes containing W-boxes and OCS elements.

  20. Root phototropism: from dogma to the mechanism of blue light perception.

    Science.gov (United States)

    Kutschera, Ulrich; Briggs, Winslow R

    2012-03-01

    In roots, the "hidden half" of all land plants, gravity is an important signal that determines the direction of growth in the soil. Hence, positive gravitropism has been studied in detail. However, since the 19th century, the response of roots toward unilateral light has also been analyzed. Based on studies on white mustard (Sinapis alba) seedlings, botanists have concluded that all roots are negatively phototropic. This "Sinapis-dogma" was refuted in a seminal study on root phototropism published a century ago, where it was shown that less then half of the 166 plant species investigated behave like S. alba, whereas 53% displayed no phototropic response at all. Here we summarize the history of research on root phototropism, discuss this phenomenon with reference to unpublished data on garden cress (Lepidium sativum) seedlings, and describe the effects of blue light on the negative bending response in Thale cress (Arabidopsis thaliana). The ecological significance of root phototropism is discussed and the relationships between gravi- and phototropism are outlined, with respect to the starch-statolith-theory of gravity perception. Finally, we present an integrative model of gravi- and blue light perception in the root tip of Arabidopsis seedlings. This hypothesis is based on our current view of the starch-statolith-concept and light sensing via the cytoplasmic red/blue light photoreceptor phytochrome A and the plasma membrane-associated blue light receptor phototropin-1. Open questions and possible research agendas for the future are summarized.

  1. Sleep disturbances are related to decreased transmission of blue light to the retina caused by lens yellowing

    DEFF Research Database (Denmark)

    Kessel, Line; Siganos, Galatios; Jørgensen, Torben

    2011-01-01

    Sleep pattern and circadian rhythms are regulated via the retinohypothalamic tract in response to stimulation of a subset of retinal ganglion cells, predominantly by blue light (450-490 nm). With age, the transmission of blue light to the retina is reduced because of the aging process of the human...

  2. In vivo optical imaging of physiological responses to photostimulation in human photoreceptors

    CERN Document Server

    Hillmann, Dierck; Pfäffle, Clara; Sudkamp, Helge; Franke, Gesa; Hüttmann, Gereon

    2016-01-01

    Non-invasive functional imaging of molecular and cellular processes of vision is expected to have immense impact on research and clinical diagnostics. Although suitable intrinsic optical signals (IOS) have been observed ex vivo and in immobilized animals in vivo, it was so far not possible to obtain convincing IOS of photoreceptor activity in humans in vivo. Here, we observed spatially and temporally clearly resolved changes in the optical path length of the photoreceptor outer segment as response to an optical stimulus in living human. To obtain these changes, we evaluated phase data of a parallelized and computationally aberration-corrected optical coherence tomography (OCT) system. The non-invasive detection of optical path length changes shows the neuronal photoreceptor activity of single cones in living human retina, and, more importantly, it provides a new diagnostic option in ophthalmology and neurology and could give new insights into visual phototransduction in humans.

  3. Blue light does not inhibit nodulation in Sesbania rostrata.

    Science.gov (United States)

    Shimomura, Aya; Arima, Susumu; Hayashi, Makoto; Maymon, Maskit; Hirsch, Ann M; Suzuki, Akihiro

    2017-01-02

    Earlier, we reported that root nodulation was inhibited by blue light irradiation of Lotus japonicus. Because some legumes do not establish nodules exclusively on underground roots, we investigated whether nodule formation in Sesbania rostrata, which forms both root and "stem" nodules following inoculation with Azorhizobium caulinodans, is inhibited by blue light as are L. japonicus nodules. We found that neither S. rostrata nodulation nor nitrogen fixation was inhibited by blue light exposure. Moreover, although A. caulinodans proliferation was not affected by blue light irradiation, bacterial survival was decreased. Therefore, blue light appears to impose different responses depending on the legume-rhizobial symbiosis.

  4. In vitro transdifferentiation of human peripheral blood mononuclear cells to photoreceptor-like cells

    Directory of Open Access Journals (Sweden)

    Yukari Komuta

    2016-06-01

    Full Text Available Direct reprogramming is a promising, simple and low-cost approach to generate target cells from somatic cells without using induced pluripotent stem cells. Recently, peripheral blood mononuclear cells (PBMCs have attracted considerable attention as a somatic cell source for reprogramming. As a cell source, PBMCs have an advantage over dermal fibroblasts with respect to the ease of collecting tissues. Based on our studies involving generation of photosensitive photoreceptor cells from human iris cells and human dermal fibroblasts by transduction of photoreceptor-related transcription factors via retrovirus vectors, we transduced these transcription factors into PBMCs via Sendai virus vectors. We found that retinal disease-related genes were efficiently detected in CRX-transduced cells, most of which are crucial to photoreceptor functions. In functional studies, a light-induced inward current was detected in some CRX-transduced cells. Moreover, by modification of the culture conditions including additional transduction of RAX1 and NEUROD1, we found a greater variety of retinal disease-related genes than that observed in CRX-transduced PBMCs. These data suggest that CRX acts as a master control gene for reprogramming PBMCs into photoreceptor-like cells and that our induced photoreceptor-like cells might contribute to individualized drug screening and disease modeling of inherited retinal degeneration.

  5. Effects of Ranibizumab and Aflibercept on Human Müller Cells and Photoreceptors under Stress Conditions

    Science.gov (United States)

    Shen, Weiyong; Yau, Belinda; Lee, So-Ra; Zhu, Ling; Yam, Michelle; Gillies, Mark C.

    2017-01-01

    Anti-vascular endothelial growth factor (VEGF) therapy has revolutionized the treatment of retinal vascular diseases. However, constitutive VEGF also acts as a trophic factor on retinal non-vascular cells. We have studied the effects of aflibercept and ranibizumab on human Müller cells and photoreceptors exposed to starvation media containing various concentrations of glucose, with or without CoCl2-induced hypoxia. Cell survival was assessed by calcein-AM cell viability assays. Expression of heat shock proteins (Hsp) and redox proteins thioredoxin 1 and 2 (TRX1, TRX2) was studied by Western blots. The production of neurotrophic factors in Müller cells and interphotoreceptor retinoid-binding protein (IRBP) in photoreceptors was measured by enzyme-linked immunosorbent assays. Aflibercept and ranibizumab did not affect the viability of both types of cells. Neither aflibercept nor ranibizumab affected the production of neurotrophic factors or expression of Hsp60 and Hsp90 in Müller cells. However, aflibercept but not ranibizumab affected the expression of Hsp60, Hsp9, TRX1 and TRX2 in photoreceptors. Aflibercept and ranibizumab both inhibited the production of IRBP in photoreceptors, aflibercept more so than ranibizumab. Our data indicates that the potential influence of aflibercept and ranibizumab on photoreceptors should be specifically monitored in clinical studies. PMID:28257068

  6. Blue light does not impair wound healing in vitro.

    Science.gov (United States)

    Masson-Meyers, Daniela Santos; Bumah, Violet Vakunseh; Enwemeka, Chukuka Samuel

    2016-07-01

    Irradiation with red or near infrared light promotes tissue repair, while treatment with blue light is known to be antimicrobial. Consequently, it is thought that infected wounds could benefit more from combined blue and red/infrared light therapy; but there is a concern that blue light may slow healing. We investigated the effect of blue 470nm light on wound healing, in terms of wound closure, total protein and collagen synthesis, growth factor and cytokines expression, in an in vitro scratch wound model. Human dermal fibroblasts were cultured for 48h until confluent. Then a linear scratch wound was created and irradiated with 3, 5, 10 or 55J/cm(2). Control plates were not irradiated. Following 24h of incubation, cells were fixed and stained for migration and fluorescence analyses and the supernatant collected for quantification of total protein, hydroxyproline, bFGF, IL-6 and IL-10. The results showed that wound closure was similar for groups treated with 3, 5 and 10J/cm(2), with a slight improvement with the 5J/cm(2) dose, and slower closure with 55J/cm(2) plight at low fluence does not impair in vitro wound healing. The significant decrease in IL-6 suggests that 470nm light is anti-inflammatory.

  7. Damage threshold in adult rabbit eyes after scleral cross-linking by riboflavin/blue light application.

    Science.gov (United States)

    Iseli, Hans Peter; Körber, Nicole; Karl, Anett; Koch, Christian; Schuldt, Carsten; Penk, Anja; Liu, Qing; Huster, Daniel; Käs, Josef; Reichenbach, Andreas; Wiedemann, Peter; Francke, Mike

    2015-10-01

    Several scleral cross-linking (SXL) methods were suggested to increase the biomechanical stiffness of scleral tissue and therefore, to inhibit axial eye elongation in progressive myopia. In addition to scleral cross-linking and biomechanical effects caused by riboflavin and light irradiation such a treatment might induce tissue damage, dependent on the light intensity used. Therefore, we characterized the damage threshold and mechanical stiffening effect in rabbit eyes after application of riboflavin combined with various blue light intensities. Adult pigmented and albino rabbits were treated with riboflavin (0.5 %) and varying blue light (450 ± 50 nm) dosages from 18 to 780 J/cm(2) (15 to 650 mW/cm(2) for 20 min). Scleral, choroidal and retinal tissue alterations were detected by means of light microscopy, electron microscopy and immunohistochemistry. Biomechanical changes were measured by shear rheology. Blue light dosages of 480 J/cm(2) (400 mW/cm(2)) and beyond induced pathological changes in ocular tissues; the damage threshold was defined by the light intensities which induced cellular degeneration and/or massive collagen structure changes. At such high dosages, we observed alterations of the collagen structure in scleral tissue, as well as pigment aggregation, internal hemorrhages, and collapsed blood vessels. Additionally, photoreceptor degenerations associated with microglia activation and macroglia cell reactivity in the retina were detected. These pathological alterations were locally restricted to the treated areas. Pigmentation of rabbit eyes did not change the damage threshold after a treatment with riboflavin and blue light but seems to influence the vulnerability for blue light irradiations. Increased biomechanical stiffness of scleral tissue could be achieved with blue light intensities below the characterized damage threshold. We conclude that riboflavin and blue light application increased the biomechanical stiffness of scleral tissue at

  8. A molecular movie at 1.8 A resolution displays the photocycle of photoactive yellow protein, a eubacterial blue-light receptor, from nanoseconds to seconds.

    NARCIS (Netherlands)

    Ren, Z.; Perman, B.; Srajer, V.; Teng, T.Y.; Pradervand, C.; Bourgeois, D.; Schotte, F.; Ursby, T.; Kort, R.

    2001-01-01

    The photocycle of the bacterial blue-light photoreceptor, photoactive yellow protein, was stimulated by illumination of single crystals by a 7 ns laser pulse. The molecular events were recorded at high resolution by time-resolved X-ray Laue diffraction as they evolved in real time, from 1 ns to seco

  9. Antimicrobial blue light therapy for multidrug-resistant Acinetobacter baumannii infection in a mouse burn model: implications for prophylaxis and treatment of combat-related wound infections.

    Science.gov (United States)

    Zhang, Yunsong; Zhu, Yingbo; Gupta, Asheesh; Huang, Yingying; Murray, Clinton K; Vrahas, Mark S; Sherwood, Margaret E; Baer, David G; Hamblin, Michael R; Dai, Tianhong

    2014-06-15

    In this study, we investigated the utility of antimicrobial blue light therapy for multidrug-resistant Acinetobacter baumannii infection in a mouse burn model. A bioluminescent clinical isolate of multidrug-resistant A. baumannii was obtained. The susceptibility of A. baumannii to blue light (415 nm)-inactivation was compared in vitro to that of human keratinocytes. Repeated cycles of sublethal inactivation of bacterial by blue light were performed to investigate the potential resistance development of A. baumannii to blue light. A mouse model of third degree burn infected with A. baumannii was developed. A single exposure of blue light was initiated 30 minutes after bacterial inoculation to inactivate A. baumannii in mouse burns. It was found that the multidrug-resistant A. baumannii strain was significantly more susceptible than keratinocytes to blue light inactivation. Transmission electron microscopy revealed blue light-induced ultrastructural damage in A. baumannii cells. Fluorescence spectroscopy suggested that endogenous porphyrins exist in A. baumannii cells. Blue light at an exposure of 55.8 J/cm(2) significantly reduced the bacterial burden in mouse burns. No resistance development to blue light inactivation was observed in A. baumannii after 10 cycles of sublethal inactivation of bacteria. No significant DNA damage was detected in mouse skin by means of a skin TUNEL assay after a blue light exposure of 195 J/cm(2).

  10. Dark therapy for bipolar disorder using amber lenses for blue light blockade.

    Science.gov (United States)

    Phelps, James

    2008-01-01

    "Dark Therapy", in which complete darkness is used as a mood stabilizer in bipolar disorder, roughly the converse of light therapy for depression, has support in several preliminary studies. Although data are limited, darkness itself appears to organize and stabilize circadian rhythms. Yet insuring complete darkness from 6 p.m. to 8 a.m. the following morning, as used in several studies thus far, is highly impractical and not accepted by patients. However, recent data on the physiology of human circadian rhythm suggests that "virtual darkness" may be achievable by blocking blue wavelengths of light. A recently discovered retinal photoreceptor, whose fibers connect only to the biological clock region of the hypothalamus, has been shown to respond only to a narrow band of wavelengths around 450 nm. Amber-tinted safety glasses, which block transmission of these wavelengths, have already been shown to preserve normal nocturnal melatonin levels in a light environment which otherwise completely suppresses melatonin production. Therefore it may be possible to influence human circadian rhythms by using these lenses at night to blunt the impact of electrical light, particularly the blue light of ubiquitous television screens, by creating a "virtual darkness". One way to investigate this would be to provide the lenses to patients with severe sleep disturbance of probable circadian origin. A preliminary case series herein demonstrates that some patients with bipolar disorder experience reduced sleep-onset latency with this approach, suggesting a circadian effect. If amber lenses can effectively simulate darkness, a broad range of conditions might respond to this inexpensive therapeutic tool: common forms of insomnia; sleep deprivation in nursing mothers; circadian rhythm disruption in shift workers; and perhaps even rapid cycling bipolar disorder, a difficult- to -treat variation of a common illness.

  11. Blue-light-induced rapid chloroplast de-anchoring in Vallisneria epidermal cells

    Institute of Scientific and Technical Information of China (English)

    Yuuki Sakai; Shin-Ichiro Inoue; Akiko Harada; Ken-Ichiro Shimazaki; Shingo Takagi

    2015-01-01

    In the outer periclinal cytoplasm of leaf epidermal cells of an aquatic angiosperm Vallisneria, blue light induces “chloroplast de‐anchoring”, a rapid decline in the resistance of chloroplasts against centrifugal force. Chloroplast deanchoring is known induced within 1 min of irradiation with high‐fluence‐rate blue light specifically, preceding the commencement of chloroplasts migration toward the anticlinal cytoplasm. However, its regulatory mechanism has remained elusive, although pharmacological analysis suggested that a calcium release from intracellular calcium stores is necessary for the response. In search of the responsible photoreceptors, immunoblotting analysis using antibodies against phototropins demonstrated that cross‐reactive polypeptides of 120‐kDa exist in the plasma‐membrane fraction prepared from the leaves. In vitro phosphorylation analysis revealed that 120‐kDa polypeptides were phosphorylated by exposure to blue light in a fluence‐dependent manner. The blue‐light‐induced phosphorylation activity was sensitive to a Ser/Thr kinase inhibitor, staurosporine, and unusually was retained at a high level for a long time in darkness. Furthermore, phototropin gene homologs (Vallisneria PHOTOTROPIN1 and PHOTOTROPIN2) expressed in leaves were isolated. We propose that calciumregulated chloroplast de‐anchoring, possibly mediated by phototropins, is an initial process of the blue‐light‐induced avoidance response of chloroplasts in Vallisneria.

  12. Dental resin curing blue light induced oxidative stress with reactive oxygen species production.

    Science.gov (United States)

    Yoshino, Fumihiko; Yoshida, Ayaka; Okada, Eizo; Okada, Yasue; Maehata, Yojiro; Miyamoto, Chihiro; Kishimoto, Sachi; Otsuka, Takero; Nishimura, Tomoko; Lee, Masaichi Chang-il

    2012-09-01

    Dental resin curing blue light has been used in the treatment of tooth bleaching and to restore teeth with resin-based composite fillings. However, there has been little consideration of its effect on oral tissues such as dental pulp and oral mucosa. The aim of this study was to investigate whether dental resin curing blue light irradiation affects the dental pulp, especially the blood vessels that are known as the first target of reactive oxygen species (ROS), which play an important role in vascular reactivity. We found that blue light irradiation increased the level of lipid peroxidation in isolated rat aorta blood vessels by measuring malondialdehyde. Furthermore, cell proliferative activity was decreased in a time-dependent manner and apoptosis of human aorta vascular smooth muscle cells (VSMCs) was induced. These results indicated that (ROS) such as hydrogen peroxide and hydroxyl radicals were generated in VSMCs by irradiation with blue light, and they induced cytotoxicity associated with oxidative stress, which increased lipid peroxidation and apoptosis. In addition, N-acetyl-l-cysteine, which is a typical intracellular antioxidant, protected VSMCs against cytotoxicity associated with oxidative stress. These findings suggested that antioxidants may be used to prevent oxidative stress in dental pulp by repeated and/or multiple treatments with blue light irradiation in future dental treatments.

  13. Evaluation of blue light exposure to beta brainwaves on simulated night driving

    Science.gov (United States)

    Purawijaya, Dandri Aly; Fitri, Lulu Lusianti; Suprijanto

    2015-09-01

    Numbers of night driving accident in Indonesia since 2010 are exponentially rising each year with total of loss more than 50 billion rupiah. One of the causes that contribute to night driving accident is drowsiness. Drowsiness is affected by circadian rhythm resulted from the difference of blue light quality and quantity between night and day. Blue light may effect on human physiology through non-visual pathway by suppressing melatonin hormone suppression that influence drowsiness. Meanwhile, the production of hormones and other activities in brain generate bioelectrical activity such as brainwaves and can be recorded using Electroencephalograph (EEG). Therefore, this research objective is to evaluate the effect of blue light exposure to beta brainwave emergence during night driving simulation to a driver. This research was conducted to 4 male subjects who are able to drive and have a legitimate car driving license. The driving simulator was done using SCANIA Truck Driving Simulator on freeform driving mode in dark environment. Subjects drove for total 32 minutes. The data collections were taken in 2 days with 16 minutes for each day. The 16 minutes were divided again into 8 minutes adaptation in dark and 8 minutes for driving either in blue light exposure or in total darkness. While driving the simulation, subjects' brainwaves were recorded using EEG EMOTIV 14 Channels, exposed by LED monochromatic blue light with 160 Lux from source and angle 45o and sat 1 m in front of the screen. Channels used on this research were for visual (O1; O2), cognition (F3; F4; P7; P8), and motor (FC5; FC6). EEG brainwave result was filtered with EEGLab to obtain beta waves at 13 - 30 Hz frequencies. Results showed that beta waves response to blue light varied for each subject. Blue light exposure either increased or decreased beta waves in 2 minutes pattern and maintaining beta waves on cognition and motor area in 3 out of 4 subjects. Meanwhile, blue light exposure did not maintain

  14. Microsecond light-induced proton transfer to flavin in the blue light sensor plant cryptochrome.

    Science.gov (United States)

    Langenbacher, Thomas; Immeln, Dominik; Dick, Bernhard; Kottke, Tilman

    2009-10-14

    Plant cryptochromes are blue light photoreceptors that regulate key responses in growth and daily rhythm of plants and might be involved in magnetoreception. They show structural homology to the DNA repair enzyme photolyase and bind flavin adenine dinucleotide as chromophore. Blue light absorption initiates the photoreduction from the oxidized dark state of flavin to the flavin neutral radical, which is the signaling state of the sensor. Previous time-resolved studies of the photoreduction process have been limited to observation of the decay of the radical in the millisecond time domain. We monitored faster, light-induced changes in absorption of an algal cryptochrome covering a spectral range of 375-750 nm with a streak camera setup. Electron transfer from tryptophan to flavin is completed before 100 ns under formation of the flavin anion radical. Proton transfer takes place with a time constant of 1.7 micros leading to the flavin neutral radical. Finally, the flavin radical and a tryptophan neutral radical decay with a time constant >200 micros in the millisecond and second time domain. The microsecond proton transfer has not been observed in animal cryptochromes from insects or photolyases. Furthermore, the strict separation in time of electron and proton transfer is novel in the field of flavin-containing photoreceptors. The reaction rate implies that the proton donor is not in hydrogen bonding distance to the flavin N5. Potential candidates for the proton donor and the involvement of the tryptophan triad are discussed.

  15. Genetics of the Blue Light-Dependent Signal Cascade That Controls Phototaxis in the Cyanobacterium Synechocystis sp. PCC6803.

    Science.gov (United States)

    Sugimoto, Yuki; Nakamura, Hiroshi; Ren, Shukun; Hori, Koichi; Masuda, Shinji

    2017-03-01

    The Synechocystis sp. PCC6803 can move on a solid surface in response to light, a phenomenon called phototaxis. Although many of the photoreceptors involved in phototaxis have been identified, the mechanisms that regulate directional motility of Synechocystis are not well understood. Previous studies showed that a mutant lacking the blue light-using flavin (BLUF) photoreceptor PixD exhibits negative phototaxis under conditions where the wild type responds positively. PixD interacts with the pseudo-response regulator-like protein PixE in a light-dependent manner, suggesting that this intermolecular interaction is important for phototaxis regulation, although genetic evidence has been lacking. To gain further insight into phototaxis regulation by PixD-PixE signaling, we constructed the deletion mutants ΔPixE and ΔPixD-ΔPixE, and characterized their phenotypes, which matched those of the wild type (positive phototaxis). Because ΔPixD exhibited negative phototaxis, PixE must function downstream of PixD. Under intense blue light (>100 μmol m-2 s-1; 470 nm) the wild type exhibited negative phototaxis, but ΔPixD-PixE exhibited positive phototaxis toward low-intensity blue light (∼0.8 μmol m-2 s-1; 470 nm). These results suggest that an unknown light-sensing system(s), that is necessary for directional cell movement, can be activated by low-intensity blue light; on the other hand, PixD needs high-intensity blue light to be activated. We also isolated spontaneous mutants that compensated for the pixE deletion. Genome-wide sequencing of the mutants revealed that the uncharacterized gene sll2003 regulates positive and negative phototaxis in response to light intensity. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  16. Staring at the cold sun: blue light regulation is distributed within the genus Acinetobacter.

    Directory of Open Access Journals (Sweden)

    Adrián Golic

    Full Text Available We previously showed that the opportunistic nosocomial pathogen Acinetobacter baumannii is able to sense and respond to light via BlsA, a BLUF (Blue-Light-sensing Using FAD-domain photoreceptor protein. Here, we extend our previous studies showing that light regulation is not restricted to A. baumannii, but rather widespread within the genus Acinetobacter. First, we found that blue light modulates motility and biofilm formation in many species of the genus, including members of the Acinetobacter calcoaceticus-A. baumannii complex. In many of these species blue light acts as a key factor guiding the decision between motility or sessility at 24°C, whereas in A. baumannii, light inhibits both motility and biofilm formation. We also show that light regulation of motility occurred not only at 24°C but also at 37°C in non-A. baumannii species, contrasting the situation of A. baumannii which only shows photoregulation at 24°C. Second, we show that Acinetobacter baylyi (strain ADP1 BLUF-photoreceptors can functionally replace in vivo the A. baumannii 17978 BlsA protein and that the pathways leading to biofilm formation are inversely regulated at 24°C between these two microorganisms. Finally, we found the presence of predicted genes coding BLUF-containing proteins in all Acinetobacter sequenced genomes, even though the copy number is variable among them. Phylogenetic analysis suggests a common origin for all BLUF domains present in members of this genus, and could distinguish well-differentiated clusters that group together BLUF homologs from different species, a situation particularly clear for members of the ACB complex. Despite a role played by these BLUF domain-containing proteins in the photoregulation observed in the members of the genus Acinetobacter is a likely scenario given our findings in A. baumannii and A. baylyi, further research will contribute to confirm this possibility.

  17. Gene therapy rescues photoreceptor blindness in dogs and paves the way for treating human X-linked retinitis pigmentosa.

    Science.gov (United States)

    Beltran, William A; Cideciyan, Artur V; Lewin, Alfred S; Iwabe, Simone; Khanna, Hemant; Sumaroka, Alexander; Chiodo, Vince A; Fajardo, Diego S; Román, Alejandro J; Deng, Wen-Tao; Swider, Malgorzata; Alemán, Tomas S; Boye, Sanford L; Genini, Sem; Swaroop, Anand; Hauswirth, William W; Jacobson, Samuel G; Aguirre, Gustavo D

    2012-02-07

    Hereditary retinal blindness is caused by mutations in genes expressed in photoreceptors or retinal pigment epithelium. Gene therapy in mouse and dog models of a primary retinal pigment epithelium disease has already been translated to human clinical trials with encouraging results. Treatment for common primary photoreceptor blindness, however, has not yet moved from proof of concept to the clinic. We evaluated gene augmentation therapy in two blinding canine photoreceptor diseases that model the common X-linked form of retinitis pigmentosa caused by mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene, which encodes a photoreceptor ciliary protein, and provide evidence that the therapy is effective. After subretinal injections of adeno-associated virus-2/5-vectored human RPGR with human IRBP or GRK1 promoters, in vivo imaging showed preserved photoreceptor nuclei and inner/outer segments that were limited to treated areas. Both rod and cone photoreceptor function were greater in treated (three of four) than in control eyes. Histopathology indicated normal photoreceptor structure and reversal of opsin mislocalization in treated areas expressing human RPGR protein in rods and cones. Postreceptoral remodeling was also corrected: there was reversal of bipolar cell dendrite retraction evident with bipolar cell markers and preservation of outer plexiform layer thickness. Efficacy of gene therapy in these large animal models of X-linked retinitis pigmentosa provides a path for translation to human treatment.

  18. Distribution and phylogeny of light-oxygen-voltage-blue-light-signaling proteins in the three kingdoms of life.

    Science.gov (United States)

    Krauss, Ulrich; Minh, Bui Quang; Losi, Aba; Gärtner, Wolfgang; Eggert, Thorsten; von Haeseler, Arndt; Jaeger, Karl-Erich

    2009-12-01

    Plants and fungi respond to environmental light stimuli via the action of different photoreceptor modules. One such class, responding to the blue region of light, is constituted by photoreceptors containing so-called light-oxygen-voltage (LOV) domains as sensor modules. Four major LOV families are currently identified in eukaryotes: (i) the plant phototropins, regulating various physiological effects such as phototropism, chloroplast relocation, and stomatal opening; (ii) the aureochromes, mediating photomorphogenesis in photosynthetic stramenopile algae; (iii) the plant circadian photoreceptors of the zeitlupe (ZTL)/adagio (ADO)/flavin-binding Kelch repeat F-box protein 1 (FKF1) family; and (iv) the fungal circadian photoreceptors white-collar 1 (WC-1). Blue-light-sensitive LOV signaling modules are also widespread throughout the prokaryotic world, and physiological responses mediated by bacterial LOV photoreceptors were recently reported. Thus, the question arises as to the evolutionary relationship between the pro- and eukaryotic LOV photoreceptor systems. We used Bayesian and maximum-likelihood tree reconstruction methods to infer evolutionary scenarios that might have led to the widespread appearance of LOV domains among the pro- and eukaryotes. The phylogenetic study presented here suggests a bacterial origin for the LOV domains of the four major eukaryotic LOV photoreceptor families, whereas the LOV sensor domains were most likely recruited from the bacteria in the course of plastid and mitochondrial endosymbiosis.

  19. Blue light effects on rose photosynthesis and photomorphogenesis.

    Science.gov (United States)

    Abidi, F; Girault, T; Douillet, O; Guillemain, G; Sintes, G; Laffaire, M; Ben Ahmed, H; Smiti, S; Huché-Thélier, L; Leduc, N

    2013-01-01

    Through its impact on photosynthesis and morphogenesis, light is the environmental factor that most affects plant architecture. Using light rather than chemicals to manage plant architecture could reduce the impact on the environment. However, the understanding of how light modulates plant architecture is still poor and further research is needed. To address this question, we examined the development of two rose cultivars, Rosa hybrida'Radrazz' and Rosa chinensis'Old Blush', cultivated under two light qualities. Plants were grown from one-node cuttings for 6 weeks under white or blue light at equal photosynthetic efficiencies. While plant development was totally inhibited in darkness, blue light could sustain full development from bud burst until flowering. Blue light reduced the net CO(2) assimilation rate of fully expanded leaves in both cultivars, despite increasing stomatal conductance and intercellular CO(2) concentrations. In 'Radrazz', the reduction in CO(2) assimilation under blue light was related to a decrease in photosynthetic pigment content, while in both cultivars, the chl a/b ratio increased. Surprisingly, blue light could induce the same organogenetic activity of the shoot apical meristem, growth of the metamers and flower development as white light. The normal development of rose plants under blue light reveals the strong adaptive properties of rose plants to their light environment. It also indicates that photomorphogenetic processes can all be triggered by blue wavelengths and that despite a lower assimilation rate, blue light can provide sufficient energy via photosynthesis to sustain normal growth and development in roses.

  20. Overexpressed or intraperitoneally injected human transferrin prevents photoreceptor degeneration in rd10 mice.

    Science.gov (United States)

    Picard, Emilie; Jonet, Laurent; Sergeant, Claire; Vesvres, Marie-Hélène; Behar-Cohen, Francine; Courtois, Yves; Jeanny, Jean-Claude

    2010-12-08

    Retinal degeneration has been associated with iron accumulation in age-related macular degeneration (AMD), and in several rodent models that had one or several iron regulating protein impairments. We investigated the iron concentration and the protective role of human transferrin (hTf) in rd10 mice, a model of retinal degeneration. The proton-induced X-ray emission (PIXE) method was used to quantify iron in rd10 mice 2, 3, and 4 weeks after birth. We generated mice with the β-phosphodiesterase mutation and hTf expression by crossbreeding rd10 mice with TghTf mice (rd10/hTf mice). The photoreceptor loss and apoptosis were evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling in 3-week-old rd10/hTf mice and compared with 3-week-old rd10 mice. The neuroprotective effect of hTf was analyzed in 5-day-old rd10 mice treated by intraperitoneal administration with hTf for up to 25 days. The retinal hTf concentrations and the thickness of the outer nuclear layer were quantified in all treated mice at 25 days postnatally. PIXE analysis demonstrated an age-dependent iron accumulation in the photoreceptors of rd10 mice. The rd10/hTf mice had the rd10 mutation, expressed high levels of hTf, and showed a significant decrease in photoreceptor death. In addition, rd10 mice intraperitoneally treated with hTf resulted in the retinal presence of hTf and a dose-dependent reduction in photoreceptor degeneration. Our results suggest that iron accumulation in the retinas of rd10 mutant mice is associated with photoreceptor degeneration. For the first time, the enhanced survival of cones and rods in the retina of this model has been demonstrated through overexpression or systemic administration of hTf. This study highlights the therapeutic potential of Tf to inhibit iron-induced photoreceptor cell death observed in degenerative diseases such as retinitis pigmentosa and age-related macular degeneration.

  1. After Stroke, 'Blue' Light May Help Beat the Blues

    Science.gov (United States)

    ... https://medlineplus.gov/news/fullstory_163731.html After Stroke, 'Blue' Light May Help Beat the Blues Akin ... a danger for people recovering from a debilitating stroke. But new research suggests that tweaking a rehabilitation ...

  2. The effect of blue light on periodontal biofilm growth in vitro.

    Science.gov (United States)

    Fontana, Carla R; Song, Xiaoqing; Polymeri, Angeliki; Goodson, J Max; Wang, Xiaoshan; Soukos, Nikolaos S

    2015-11-01

    We have previously shown that blue light eliminates the black-pigmented oral bacteria Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, and Prevotella melaninogenica. In the present study, the in vitro photosensitivity of the above black-pigmented microorganisms and four Fusobacteria species (Fusobacterium nucleatum ss. nucleatum, F. nucleatum ss. vincentii, F. nucleatum ss. polymorphum, Fusobacterium periodonticum) was investigated in pure cultures and human dental plaque suspensions. We also tested the hypothesis that phototargeting the above eight key periodontopathogens in plaque-derived biofilms in vitro would control growth within the dental biofilm environment. Cultures of the eight bacteria were exposed to blue light at 455 nm with power density of 80 mW/cm2 and energy fluence of 4.8 J/cm2. High-performance liquid chromatography (HPLC) analysis of bacteria was performed to demonstrate the presence and amounts of porphyrin molecules within microorganisms. Suspensions of human dental plaque bacteria were also exposed once to blue light at 455 nm with power density of 50 mW/cm2 and energy fluence of 12 J/cm2. Microbial biofilms developed from the same plaque were exposed to 455 nm blue light at 50 mW/cm2 once daily for 4 min (12 J/cm2) over a period of 3 days (4 exposures) in order to investigate the cumulative action of phototherapy on the eight photosensitive pathogens as well as on biofilm growth. Bacterial growth was evaluated using the colony-forming unit (CFU) assay. The selective phototargeting of pathogens was studied using whole genomic probes in the checkerboard DNA-DNA format. In cultures, all eight species showed significant growth reduction (p biofilms, respectively, (p biofilms. The cumulative blue light treatment suppressed biofilm growth in vitro. This may introduce a new avenue of prophylactic treatment for periodontal diseases.

  3. Blue light-dependent changes in loosely bound calcium in Arabidopsis mesophyll cells: an X-ray microanalysis study.

    Science.gov (United States)

    Łabuz, Justyna; Samardakiewicz, Sławomir; Hermanowicz, Paweł; Wyroba, Elżbieta; Pilarska, Maria; Gabryś, Halina

    2016-06-01

    Calcium is involved in the signal transduction pathway from phototropins, the blue light photoreceptor kinases which mediate chloroplast movements. The chloroplast accumulation response in low light is controlled by both phot1 and phot2, while only phot2 is involved in avoidance movement induced by strong light. Phototropins elevate cytosolic Ca(2+) after activation by blue light. In higher plants, both types of chloroplast responses depend on Ca(2+), and internal calcium stores seem to be crucial for these processes. Yet, the calcium signatures generated after the perception of blue light by phototropins are not well understood. To characterize the localization of calcium in Arabidopsis mesophyll cells, loosely bound (exchangeable) Ca(2+) was precipitated with potassium pyroantimonate and analyzed by transmission electron microscopy followed by energy-dispersive X-ray microanalysis. In dark-adapted wild-type Arabidopsis leaves, calcium precipitates were observed at the cell wall, where they formed spherical structures. After strong blue light irradiation, calcium at the apoplast prevailed, and bigger, multilayer precipitates were found. Spherical calcium precipitates were also detected at the tonoplast. After red light treatment as a control, the precipitates at the cell wall were smaller and less numerous. In the phot2 and phot1phot2 mutants, calcium patterns were different from those of wild-type plants. In both mutants, no elevation of calcium after blue light treatment was observed at the cell periphery (including the cell wall and a fragment of cytoplasm). This result confirms the involvement of phototropin2 in the regulation of Ca(2+) homeostasis in mesophyll cells.

  4. Leaf Positioning of Arabidopsis in Response to Blue Light

    Institute of Scientific and Technical Information of China (English)

    Shin-ichiro Inoue; Toshinori Kinoshita; Atsushi Takemiya; Michio Doi; Ken-ichiro Shimazaki

    2008-01-01

    Appropriate leaf positioning is essential for optimizing photosynthesis and plant growth. However, it has not been elucidated how green leaves reach and maintain their position for capturing light. We show here the regulation of leaf positioning under blue light stimuli. When 1-week-old Arabidopsis seedlings grown under white light were transferred to red light (25 μmol m-2s-t) for 5 d, new petioles that appeared were almost horizontal and their leaves were curled and slanted downward. However, when a weak blue light from above (0.1 μmol m-2s-1) was superimposed on red light, the new petioles grew obliquely upward and the leaves were flat and horizontal. The leaf positioning required both phototropin1 (phot1) and nonphototropic hypocotyl 3 (NPH3), and resulted in enhanced plant growth. In an nph3 mutant, neither optimal leaf positioning nor leaf flattening by blue light was found, and blue light-induced growth enhancement was drastically reduced. When blue light was increased from 0.1 to 5 μmol m-2s-1, normal leaf positioning and leaf flattening were induced in both phot1 and nph3 mutants, suggesting that phot2 signaling became functional and that the signaling was independent of phot1 and NPH3 in these responses. When plants were irradiated with blue light (0.1 μmol m-2s-1) from the side and red light from above, the new leaves became oriented toward the source of blue light. When we transferred these plants to both blue light and red light from above, the leaf surface changed its orientation to the new blue light source within a few hours, whereas the petioles initially were unchanged but then gradually rotated, suggesting the plasticity of leaf positioning in response to blue light. We showed the tissue expression of NPH3 and its plasma membrane localization via the coiled-coil domain and the C-terminal region. We conclude that NPH3-mediated phototropin signaling optimizes the efficiency of light perception by inducing both optimal leaf positioning and leaf

  5. Transcriptomic analysis of human retinal detachment reveals both inflammatory response and photoreceptor death.

    Directory of Open Access Journals (Sweden)

    Marie-Noëlle Delyfer

    Full Text Available BACKGROUND: Retinal detachment often leads to a severe and permanent loss of vision and its therapeutic management remains to this day exclusively surgical. We have used surgical specimens to perform a differential analysis of the transcriptome of human retinal tissues following detachment in order to identify new potential pharmacological targets that could be used in combination with surgery to further improve final outcome. METHODOLOGY/PRINCIPAL FINDINGS: Statistical analysis reveals major involvement of the immune response in the disease. Interestingly, using a novel approach relying on coordinated expression, the interindividual variation was monitored to unravel a second crucial aspect of the pathological process: the death of photoreceptor cells. Within the genes identified, the expression of the major histocompatibility complex I gene HLA-C enables diagnosis of the disease, while PKD2L1 and SLCO4A1 -which are both down-regulated- act synergistically to provide an estimate of the duration of the retinal detachment process. Our analysis thus reveals the two complementary cellular and molecular aspects linked to retinal detachment: an immune response and the degeneration of photoreceptor cells. We also reveal that the human specimens have a higher clinical value as compared to artificial models that point to IL6 and oxidative stress, not implicated in the surgical specimens studied here. CONCLUSIONS/SIGNIFICANCE: This systematic analysis confirmed the occurrence of both neurodegeneration and inflammation during retinal detachment, and further identifies precisely the modification of expression of the different genes implicated in these two phenomena. Our data henceforth give a new insight into the disease process and provide a rationale for therapeutic strategies aimed at limiting inflammation and photoreceptor damage associated with retinal detachment and, in turn, improving visual prognosis after retinal surgery.

  6. Blue light-mediated inactivation of Enterococcus faecalis in vitro.

    Science.gov (United States)

    Pileggi, Giorgio; Wataha, John C; Girard, Myriam; Grad, Iwona; Schrenzel, Jacques; Lange, Norbert; Bouillaguet, Serge

    2013-05-01

    In dentistry, residual infection remains a major cause of failure after endodontic treatment; many of these infections involve Enterococcus faecalis. In the current study, we explored the possibility that blue light activated photosensitizers could be used, in principle, to inactivate this microbe as an adjunct disinfection strategy for endodontic therapy. Three blue light absorbing photosensitizers, eosin-Y, rose bengal, and curcumin, were tested on E. faecalis grown in planktonic suspensions or biofilms. Photosensitizers were incubated for 30 min with bacteria then exposed to blue light (450-500 nm) for 240 s. Sodium hypochlorite (3%) was used as a control. After 48 h, the viability of E. faecalis was estimated by measuring colony-forming units post-exposure vs. untreated controls (CFU/mL). Blue light irradiation alone did not alter E. faecalis viability. For planktonic cultures, blue light activated eosin-Y (5 μM), rose bengal (1 μM), or curcumin (5 μM) significantly (pfaecalis viability compared to exposure to the unirradiated photochemicals. For biofilm cultures, concentrations of light-activated eosin-Y, rose bengal, and curcumin of 100, 10, and 10 μM respectively, completely suppressed E. faecalis viability (pendodontic treatment.

  7. Effects of blue light on pigment biosynthesis of Monascus.

    Science.gov (United States)

    Chen, Di; Xue, Chunmao; Chen, Mianhua; Wu, Shufen; Li, Zhenjing; Wang, Changlu

    2016-04-01

    The influence of different illumination levels of blue light on the growth and intracellular pigment yields of Monascus strain M9 was investigated. Compared with darkness, constant exposure to blue light of 100 lux reduced the yields of six pigments, namely, rubropunctatamine (RUM), monascorubramine (MOM), rubropunctatin (RUN), monascorubrin (MON), monascin (MS), and ankaflavin (AK). However, exposure to varying levels of blue light had different effects on pigment production. Exposure to 100 lux of blue light once for 30 min/day and to 100 lux of blue light once and twice for 15 min/day could enhance RUM, MOM, MS, and AK production and reduce RUN and MON compared with non-exposure. Exposure to 100 lux twice for 30 min/day and to 200 lux once for 45 min/day decreased the RUM, MOM, MS, and AK yields and increased the RUN and MON. Meanwhile, the expression levels of pigment biosynthetic genes were analyzed by real-time quantitative PCR. Results indicated that gene MpPKS5, mppR1, mppA, mppB, mmpC, mppD, MpFasA, MpFasB, and mppF were positively correlated with the yields of RUN and MON, whereas mppE and mppR2 were associated with RUM, MOM, MS, and AK production.

  8. Replacement gene therapy with a human RPGRIP1 sequence slows photoreceptor degeneration in a murine model of Leber congenital amaurosis.

    Science.gov (United States)

    Pawlyk, Basil S; Bulgakov, Oleg V; Liu, Xiaoqing; Xu, Xiaoyun; Adamian, Michael; Sun, Xun; Khani, Shahrokh C; Berson, Eliot L; Sandberg, Michael A; Li, Tiansen

    2010-08-01

    RPGR-interacting protein-1 (RPGRIP1) is localized in the photoreceptor-connecting cilium, where it anchors the RPGR (retinitis pigmentosa GTPase regulator) protein, and its function is essential for photoreceptor maintenance. Genetic defect in RPGRIP1 is a known cause of Leber congenital amaurosis (LCA), a severe, early-onset form of retinal degeneration. We evaluated the efficacy of replacement gene therapy in a murine model of LCA carrying a targeted disruption of RPGRIP1. The replacement construct, packaged in an adeno-associated virus serotype 8 (AAV8) vector, used a rhodopsin kinase gene promoter to drive RPGRIP1 expression. Both promoter and transgene were of human origin. After subretinal delivery of the replacement gene in the mutant mice, human RPGRIP1 was expressed specifically in photoreceptors, localized correctly in the connecting cilia, and restored the normal localization of RPGR. Electroretinogram and histological examinations showed better preservation of rod and cone photoreceptor function and improved photoreceptor survival in the treated eyes. This study demonstrates the efficacy of human gene replacement therapy and validates a gene therapy design for future clinical trials in patients afflicted with this condition. Our results also have therapeutic implications for other forms of retinal degenerations attributable to a ciliary defect.

  9. Optical imaging of human cone photoreceptors directly following the capture of light.

    Directory of Open Access Journals (Sweden)

    Phillip Bedggood

    Full Text Available Capture of light in the photoreceptor outer segment initiates a cascade of chemical events that inhibit neurotransmitter release, ultimately resulting in vision. The massed response of the photoreceptor population can be measured non-invasively by electrical recordings, but responses from individual cells cannot be measured without dissecting the retina. Here we used optical imaging to observe individual human cones in the living eye as they underwent bleaching of photopigment and associated phototransduction. The retina was simultaneously stimulated and observed with high intensity visible light at 1 kHz, using adaptive optics. There was marked variability between individual cones in both photosensitivity and pigment optical density, challenging the conventional assumption that photoreceptors act as identical subunits (coefficient of variation in rate of photoisomerization = 23%. There was also a pronounced inverse correlation between these two parameters (p<10(-7; the temporal evolution of image statistics revealed this to be a dynamic relationship, with cone waveguiding efficiency beginning a dramatic increase within 3 ms of light onset. Beginning as early as 2 ms after light onset and including half of cells by ∼7 ms, cone intensity showed reversals characteristic of interference phenomena, with greater delays in reversal corresponding to cones with more photopigment (p<10(-3. The timing of these changes is argued to best correspond with either the cessation of dark current, or to related events such as changes in intracellular cGMP. Cone intensity also showed fluctuations of high frequency (332±25 Hz and low amplitude (3.0±0.85%. Other groups have shown similar fluctuations that were directly evoked by light; if this corresponds to the same phenomenon, we propose that the amplitude of fluctuation may be increased by the use of a bright flash followed by a brief pause, to allow recovery of cone circulating current.

  10. Identification of intracellular phospholipases A2 in the human eye: involvement in phagocytosis of photoreceptor outer segments

    DEFF Research Database (Denmark)

    Kolko, Miriam; Wang, Jinmei; Zhan, Chen

    2007-01-01

    PURPOSE: To identify intracellular phospholipases A(2) (PLA(2)) in the human retina and to explore the role of these enzymes in human retinal pigment epithelium (RPE) phagocytosis of photoreceptor outer segments (POS). METHODS: PCR amplification and Western blot analysis were used to identify mRN...

  11. Blue-Light Filtering Spectacle Lenses: Optical and Clinical Performances.

    Science.gov (United States)

    Leung, Tsz Wing; Li, Roger Wing-Hong; Kee, Chea-Su

    2017-01-01

    To evaluate the optical performance of blue-light filtering spectacle lenses and investigate whether a reduction in blue light transmission affects visual performance and sleep quality. Experiment 1: The relative changes in phototoxicity, scotopic sensitivity, and melatonin suppression of five blue-light filtering plano spectacle lenses were calculated based on their spectral transmittances measured by a spectrophotometer. Experiment 2: A pseudo-randomized controlled study was conducted to evaluate the clinical performance of two blue-light filtering spectacle lenses (BF: blue-filtering anti-reflection coating; BT: brown-tinted) with a regular clear lens (AR) serving as a control. A total of eighty computer users were recruited from two age cohorts (young adults: 18-30 yrs, middle-aged adults: 40-55 yrs). Contrast sensitivity under standard and glare conditions, and colour discrimination were measured using standard clinical tests. After one month of lens wear, subjective ratings of lens performance were collected by questionnaire. All tested blue-light filtering spectacle lenses theoretically reduced the calculated phototoxicity by 10.6% to 23.6%. Although use of the blue-light filters also decreased scotopic sensitivity by 2.4% to 9.6%, and melatonin suppression by 5.8% to 15.0%, over 70% of the participants could not detect these optical changes. Our clinical tests revealed no significant decrease in contrast sensitivity either with (95% confidence intervals [CI]: AR-BT [-0.05, 0.05]; AR-BF [-0.05, 0.06]; BT-BF [-0.06, 0.06]) or without glare (95% CI: AR-BT [-0.01, 0.03]; AR-BF [-0.01, 0.03]; BT-BF [-0.02, 0.02]) and colour discrimination (95% CI: AR-BT [-9.07, 1.02]; AR-BF [-7.06, 4.46]; BT-BF [-3.12, 8.57]). Blue-light filtering spectacle lenses can partially filter high-energy short-wavelength light without substantially degrading visual performance and sleep quality. These lenses may serve as a supplementary option for protecting the retina from potential

  12. Blue-light emitting triazolopyridinium and triazoloquinolinium salts

    KAUST Repository

    Carboni, Valentina

    2017-01-27

    Compounds that emit blue light are of interest for applications that include optoelectronic devices and chemo/biosensing and imaging. The design and synthesis of small organic molecules that can act as high-efficiency deep-blue-light emitters in the solid state and can be easily processed from solutions represents a significant challenge. Herein we present the preparation and photophysical, photochemical and electrochemical properties of a series of triazolopyridinium and triazoloquinolinium compounds. The compounds are soluble in water or polar organic solvents and exhibit photoluminescence in the blue region of the spectrum in fluid solution, in the solid state and in a frozen matrix.

  13. Blue light dosage affects carotenoids and tocopherols in microgreens.

    Science.gov (United States)

    Samuolienė, Giedrė; Viršilė, Akvilė; Brazaitytė, Aušra; Jankauskienė, Julė; Sakalauskienė, Sandra; Vaštakaitė, Viktorija; Novičkovas, Algirdas; Viškelienė, Alina; Sasnauskas, Audrius; Duchovskis, Pavelas

    2017-08-01

    Mustard, beet and parsley were grown to harvest time under selected LEDs: 638+660+731+0% 445nm; 638+660+731+8% 445nm; 638+660+731+16% 445nm; 638+660+731+25% 445nm; 638+660+731+33% 445nm. From 1.2 to 4.3 times higher concentrations of chlorophylls a and b, carotenoids, α- and β-carotenes, lutein, violaxanthin and zeaxanthin was found under blue 33% treatment in comparison to lower blue light dosages. Meanwhile, the accumulation of metabolites, which were not directly connected with light reactions, such as tocopherols, was more influenced by lower (16%) blue light dosage, increasing about 1.3 times. Thus, microgreen enrichment of carotenoid and xanthophyll pigments may be achieved using higher (16-33%) blue light intensities. Changes in metabolite quantities were not the result of changes of other carotenoid concentration, but were more influenced by light treatment and depended on the species. Significant quantitative changes in response to blue light percentage were obtained for both directly and not directly light-dependent metabolite groups. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Blue light inhibits the growth of B16 melanoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Ohara, Masayuki; Katoh, Osamu; Watanabe, Hiromitsu [Hiroshima Univ. (Japan). Research Inst. for Radiation Biology and Medicine; Kawashima, Yuzo [Otsuka Pharmaceutical Factory, Inc., Naruto, Tokushima (Japan)

    2002-05-01

    Although a number of studies have been carried out to examine the biological effects of radiation and ultraviolet radiation (UV), little is known concerning the effects of visible light. In the present study, exposure of B16 melanoma cells to blue light (wavelength 470 nm, irradiance 5.7 mW/cm{sup 2}) from a light-emitting diode (LED) inhibited cell growth in proportion to the period of exposure, with no increase observed in the number of dead cells. The number of B16 melanoma colonies that formed after exposure to blue light for 20 min was only slightly less than that in non-exposed controls, but the colony size as assessed by the area covered by colonies and cell counts per colony were markedly decreased. The percentages of G0/G1 and G2/M phase cells were markedly increased, with a reduction in S phase cells as determined by flow cytometry after exposure to blue light. Furthermore, analysis of the incorporation of 5-bromo-2'-deoxyuridine (BrdU) into DNA also showed a reduction in the percentage of S phase cells after exposure. These results indicate that blue light exerts cytostatic effects, but not a cytocidal action, on B16 melanoma cells. (author)

  15. The Subcellular Localization and Blue-Light-Induced Movement of Phototropin 1-GFP in Etiolated Seedlings of Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    Ying-Lang Wan; William Eisinger; David Ehrhardt; Ulrich Kubitscheck; Frantisek Baluska; Winslow Briggs

    2008-01-01

    Phototropin 1 (phot1) is a photoreceptor for phototropism, chloroplast movement, stomatal opening, leaf expansion, and solar tracking in response to blue light. Following earlier work with PHOT1::GFP (Sakamoto and Briggs,2002), we investigated the pattern of cellular and subcellular localization of phot1 in 3-4 d old etiolated seedlings of Arabidopsis thalinana. As expressed from native upstream sequences, the PHOT1::GFP fusion protein is expressed strongly in the abaxial tissues of the cotyledons and in the elongating regions of the hypocotyl. It is moderately expressed in the shoot/root transition zone and in cells near the root apex. A fluorescence signal is undetectable in the root epidermis, root cap, and root apical meristem itself. The plasma membranes of mesophyll cells near the cotyledon margin appear labeled uniformly but cross-walls created by recent cell divisions are more strongly labeled. The pattern of labeling of individual cell types varies with cell type and developmental stage. Blue-light treatment causes PHOT1::GFP, initially relatively evenly distributed at the plasma membrane, to become reorganized into a distinct mosaic with strongly labeled punctate areas and other areas completely devoid of fluorescence-a phenomenon best observed in cortical cells in the hypocotyl elongation region. Concomitant with or following this reorganization, PHOT1::GFP moves into the cytoplasm in all cell types investigated except for guard cells. It disappears from the cytoplasm by an unidentified mechanism after several hours in darkness. Neither its appearance in the cytoplasm nor its eventual disappearance in darkness is prevented by the translation inhibitor cycloheximide, although the latter process is retarded. We hypothesize that blue-light-induced phot1 relocalization modulates blue-light-activated signal transduction.

  16. LED 蓝光危害研究%Research of LED Blue Light Hazard

    Institute of Scientific and Technical Information of China (English)

    赵介军; 乔波; 过峰

    2015-01-01

    随着人们对于照明产品光生物效应的关注, LED照明产品的光生物辐射安全问题,尤其是视网膜蓝光危害已成为人们对于LED产品望而却步的一个重要原因。通过研究LED的蓝光危害,分析了LED蓝光危害产生的原因和可能对人体造成的伤害。并通过实验调研市场上LED照明产品的蓝光危害现状,阐述了如何正确的使用LED产品,从而有效避免蓝光辐射危害。%LED lighting products with its beneficial characteristics, such as energy saving, environmental protection, long life, small size, and etc, have gradually entered people’s life.People started to care about the photobiological effects of lighting products.The photobiological radiation safety of LED lighting products, especially the retinal blue light hazard has become an important reason why people do not choose LED products. This paper analyzed the reasons and their possible harms to the human body which may be caused by LED blue light hazard.And by performing research on current situation of LED lighting products blue light hazard in market, it described how to properly use LED products so as to effectively prevent blue light hazards.

  17. Antimicrobial activity and cytotoxicity of 3 photosensitizers activated with blue light.

    Science.gov (United States)

    Bulit, Florence; Grad, Iwona; Manoil, Daniel; Simon, Stéphane; Wataha, John C; Filieri, Anna; Feki, Anis; Schrenzel, Jacques; Lange, Norbert; Bouillaguet, Serge

    2014-03-01

    Pulp repair is less likely to occur when dentin or pulpal tissue remains infected after caries excavation. Yet there are currently few options to kill residual bacteria without damaging resident cells. The current study has evaluated the effect of 3 blue light-activated chemicals on the viability of lactobacilli, odontoblast-like cells (MDPC-23), undifferentiated pulp cells (OD21), and human embryonic stem cells (hESC H1). Bacteria were incubated for 15 minutes with curcumin, eosin Y, or rose bengal and then irradiated with blue light (240 seconds). Bacteria were labeled with LIVE/DEAD BacLight Bacterial Viability kit, and viability was assessed by fluorescence-activated cell sorting. Cytotoxicity assays were performed on MDPC-23 cells, OD21, and hESC H1 cells grown in 24-well plates and exposed to the same photosensitizer-light combination. After 24 hours, cellular response was measured by using the methyl-thiazol-diphenyl-tetrazolium assay. Results were statistically analyzed by using one-way analysis of variance and Tukey multiple comparison intervals (α = 0.05). Bacterial viability was significantly reduced after exposure to different combinations of light and photosensitizers; mitochondrial activity of cultured cells remained unaffected when exposed to the same conditions, suggesting a good therapeutic index in vitro. Blue light-mediated disinfection is promising for the development of new treatment strategies designed to promote pulp repair after carious exposure. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  18. Interphotoreceptor matrix-poly(ϵ-caprolactone composite scaffolds for human photoreceptor differentiation

    Directory of Open Access Journals (Sweden)

    Petr Baranov

    2014-10-01

    Full Text Available Tissue engineering has been widely applied in different areas of regenerative medicine, including retinal regeneration. Typically, artificial biopolymers require additional surface modification (e.g. with arginine–glycine–aspartate-containing peptides or adsorption of protein, such as fibronectin, before cell seeding. Here, we describe an alternative approach for scaffold design: the manufacture of hybrid interphotoreceptor matrix-poly (ϵ-caprolactone scaffolds, in which the insoluble extracellular matrix of the retina is incorporated into a biodegradable polymer well suited for transplantation. The incorporation of interphotoreceptor matrix did not change the topography of polycaprolactone film, although it led to a slight increase in hydrophilic properties (water contact angle measurements. This hybrid scaffold provided sufficient stimuli for human retinal progenitor cell adhesion and inhibited proliferation, leading to differentiation toward photoreceptor cells (expression of Crx, Nrl, rhodopsin, ROM1. This scaffold may be used for transplantation of retinal progenitor cells and their progeny to treat retinal degenerative disorders.

  19. The Trichoderma atroviride cryptochrome/photolyase genes regulate the expression of blr1-independent genes both in red and blue light.

    Science.gov (United States)

    García-Esquivel, Mónica; Esquivel-Naranjo, Edgardo U; Hernández-Oñate, Miguel A; Ibarra-Laclette, Enrique; Herrera-Estrella, Alfredo

    2016-04-01

    Quantitative transcriptome analysis led to the identification of 331 transcripts regulated by white light. Evaluation of the response to white light in mutants affected in the previously characterized blue-light receptor Blr1, demonstrated the existence of both Blr1-dependent and independent responses. Functional categorization of the light responsive genes indicated the effect of light on regulation of various transcription factors, regulators of chromatin structure, signaling pathways, genes related to different kinds of stress, metabolism, redox adjustment, and cell cycle among others. In order to establish the participation of other photoreceptors, gene expression was validated in response to different wavelengths. Gene regulation by blue and red light suggests the involvement of several photoreceptors in integrating light signals of different wavelengths in Trichoderma atroviride. Functional analysis of potential blue light photoreceptors suggests that several perception systems for different wavelengths are involved in the response to light. Deletion of cry1, one of the potential photoreceptors, resulted in severe reduction in the photoreactivation capacity of the fungus, as well as a change in gene expression under blue and red light.

  20. Phototropins and Their LOV Domains: Versatile Plant Blue-Light Receptors

    Institute of Scientific and Technical Information of China (English)

    Winslow R. Briggs; Tong-Seung Tseng; Hae-Young Cho; Trevor E. Swartz; Stuart Sullivan; Roberto A. Bogomolni; Eirini Kaiserli; John M. Christie

    2007-01-01

    The phototropins phot1 and phot2 are plant blue-light receptors that mediate phototropism, chloroplast movements, stomatal opening, leaf expansion, the rapid inhibition of hypocotyl growth in etiolated seedlings,and possibly solar tracking by leaves in those species in which it occurs. The phototropins are plasma membrane-associated hydrophilic proteins with two chromophore domains (designated LOV1 and LOV2for their resemblance to domains in other signaling proteins that detect light, oxygen, or voltage) in their Nterminal half and a classic serine/threonine kinase domain in their C-terminal half. Both chromophore domains bind flavin mononucleotide (FMN) and both undergo light-activated formation of a covalent bond between a nearby cysteine and the C(4a) carbon of the FMN to form the signaling state. LOV2-cysteinyl adduct formation leads to the release downstream of a tightly bound amphipathic α-helix, a step required for activation of the kinase function. This cysteinyl adduct then slowly decays over a matter of seconds or minutes to return the photoreceptor chromophore modules to their ground state. Functional LOV2 is required for light-activated phosphorylation and for various blue-light responses mediated by the phototropins. The function of LOV1 is still unknown, although it may serve to modulate the signal generated by LOV2. The LOV domain is an ancient chromophore module found in a wide range of otherwise unrelated proteins in fungi and prokaryotes, the latter including cyanobacteria, eubacteria, and archaea.Further general reviews on the phototropins are those by Celaya and Liscum (2005) and Christie and Briggs(2005).

  1. Photoreceptor engineering

    Directory of Open Access Journals (Sweden)

    Thea eZiegler

    2015-06-01

    Full Text Available Sensory photoreceptors not only control diverse adaptive responses in Nature, but as light-regulated actuators they also provide the foundation for optogenetics, the non-invasive and spatiotemporally precise manipulation of cellular events by light. Novel photoreceptors have been engineered that establish control by light over manifold biological processes previously inaccessible to optogenetic intervention. Recently, photoreceptor engineering has witnessed a rapid development, and light-regulated actuators for the perturbation of a plethora of cellular events are now available. Here, we review fundamental principles of photoreceptors and light-regulated allostery. Photoreceptors dichotomize into associating receptors that alter their oligomeric state as part of light-regulated allostery and non-associating receptors that do not. A survey of engineered photoreceptors pinpoints light-regulated association reactions and order-disorder transitions as particularly powerful and versatile design principles. Photochromic photoreceptors that are bidirectionally toggled by two light colors augur enhanced spatiotemporal resolution and use as photoactivatable fluorophores. By identifying desirable traits in engineered photoreceptors, we provide pointers for the design of future, light-regulated actuators.

  2. Blue-light mediated accumulation of nuclear-encoded transcripts coding for proteins of the thylakoid membrane is absent in the phytochrome-deficient aurea mutant of tomato.

    Science.gov (United States)

    Oelmüller, R; Kendrick, R E; Briggs, W R

    1989-08-01

    Polyclonal antibodies against pea phytochrome detect 2 protein bands (about 116 and 120 kDa) on blots of crude protein extracts and protein of microsomal preparations of dark-grown tomato seedlings. Both protein bands are undetectable in Western blots of the aurea mutant extracts. Neither protein band is detectable after isogenic wild-type seedlings are illuminated with 3 h of red light, either in the crude extract or in the membrane fraction of the irradiated seedlings; this result is consistent with the hypothesis that both bands are phytochrome. When dark-grown wild-type seedlings are illuminated with 3 h of red light or blue light against a red light background, the transcript levels for chlorophyll a/b-binding proteins of photosystem I and II, plastocyanin, and the subunit II of photosystem I increase. In all cases, the same fluence rate of blue light is much more effective than red light alone, a result that indicates the involvement of a blue/UV-A light photoreceptor in addition to the involvement of the far-red-absorbing form of phytochrome, Pfr. The aurea mutant responds neither to red light nor to blue light. Thus, no Pfr-independent induction of the four transcripts by a blue/UV-A light photoreceptor can be measured in the aurea mutant.

  3. Effects of blue light on gametophyte development of Laminaria japonica (Laminariales, Phaeophyta)

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Laminaria gametophyte was greatly influenced by light in its growth and development. Using light-emitting diodes (LED) as blue and red light sources, we analyzed the light effect on gametophytes development of Laminaria japonica Aresch. The gametophytes were obtained from zoospores collected in April, May,July, 2003 and September, 2004. We found that the growth of gametophytes was stimulated by increasing intensity of blue light (BL) and red light (RL) illumination, of which BL was obviously stronger than that of RL. The fertilization of gametophytes depended largely on BL, and only sufficient BL illumination could take the reproductive effect. In addition, we noticed that there was a significant difference in light responses for gametophytes developed from zoospore collected in different times. For zoospores released in April, under BL1 (73.90 μmol sperms respectively, and further developed towards sporophytes. However, for gametophytes developed in May,July or September, they became multi-cellular and never formed oogonia or antheridia. It is believed that the Laminaria sporangium maturation stage could affect the gametophytes reaction to BL under laboratory culture conditions. Therefore, cryptochrome- or phototropin-like BL photoreceptors is probably involved in BL-induced development of Laminaria gametophytes.

  4. Autophosphorylation, electrophoretic mobility and immunoreaction of oat phototropin 1 under UV and blue Light.

    Science.gov (United States)

    Knieb, Elke; Salomon, Michael; Rüdiger, Wolfhart

    2005-01-01

    Phototropins are UV-A/blue light photoreceptors containing two flavin mononucleotide (FMN)-binding domains, light, oxygen and voltage (LOV)1 and LOV2, of which LOV2 is more sensitive toward light and more important for the physiological response compared with LOV1. Some physiological responses are plant phototropism, chloroplast migration and stomatal opening. Oat phototropin 1 together with light-dependent autophosphorylation shows a reduced electrophoretic mobility and reduced immunoreaction against a heterologous antiserum; both effects were suggested to be caused by phosphorylation at the same sites (M. Salomon, E. Knieb, T. von Zeppelin and W. Rudiger [2003] Biochemistry 42, 4217-4225). In this study, we show that both effects can be separated from each other: at low temperature, reduced immunoreaction preceded the mobility shift, and irradiation with UV-C light led to the mobility shift without the loss of immunoreactivity. We demonstrated that UV-C light at 280 nm, which does not match any absorption maximum of FMN, leads to autophosphorylation of phototropin. It is hypothesized that UV-C light causes differential activation of the LOV domains via energy transfer from aromatic amino acids.

  5. Anthocyanin Accumulation Mediated by Blue Light and Cytokinin in Arabidopsis Seedlings

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    It has been reported that pigmentation in plants is stimulated by light and cytokinin (CTK); however, the signaling pathways and the relationship between light and CTK involved in the regulation of anthocyanin accumulation remain to be elucidated. We investigated (i) the role of blue light (BL) and CTK in anthocyanin accumulation; and (ii) the relationship between BL and CTK in wild type (WT) and hy4 mutants of Arabidopsis thaliana. Two-d-old seedlings grown on medium with or without kinetin (KT) or zeatin (ZT) in darkness were irradiated using BL at different fluence rates for 3 d before the anthocyanin content was determined using a spectrophotometric method. Anthocyanin accumulation was strongly induced by BL in WT seedlings but not in hy4 seedlings, which demonstrated that CRY1 is the main photoreceptor for BL. Both KT and ZT enhanced the response of the WT seedlings to BL in a dose-dependent manner, whereas they were not sufficient to promote anthocyanin accumulation in darkness. In addition, data from experiments using the hy4 mutant showed that the CTK effect of BL was also CRY1-dependent. The results from experiments with three different treatment programs showed that the relationship between BL and KT in anthocyanin accumulation of Arabidopsis seedlings seems neither multiplicative nor additive coaction, but rather interaction. BL is necessary for anthocyanin accumulation, and KT might be involved in the BL signaling pathway.

  6. A plant-specific protein essential for blue-light-induced chloroplast movements.

    Science.gov (United States)

    DeBlasio, Stacy L; Luesse, Darron L; Hangarter, Roger P

    2005-09-01

    In Arabidopsis (Arabidopsis thaliana), light-dependent chloroplast movements are induced by blue light. When exposed to low fluence rates of light, chloroplasts accumulate in periclinal layers perpendicular to the direction of light, presumably to optimize light absorption by exposing more chloroplast area to the light. Under high light conditions, chloroplasts become positioned parallel to the incoming light in a response that can reduce exposure to light intensities that may damage the photosynthetic machinery. To identify components of the pathway downstream of the photoreceptors that mediate chloroplast movements (i.e. phototropins), we conducted a mutant screen that has led to the isolation of several Arabidopsis mutants displaying altered chloroplast movements. The plastid movement impaired1 (pmi1) mutant exhibits severely attenuated chloroplast movements under all tested fluence rates of light, suggesting that it is a necessary component for both the low- and high-light-dependant chloroplast movement responses. Analysis of pmi1 leaf cross sections revealed that regardless of the light condition, chloroplasts are more evenly distributed in leaf mesophyll cells than in the wild type. The pmi1-1 mutant was found to contain a single nonsense mutation within the open reading frame of At1g42550. This gene encodes a plant-specific protein of unknown function that appears to be conserved among angiosperms. Sequence analysis of the protein suggests that it may be involved in calcium-mediated signal transduction, possibly through protein-protein interactions.

  7. New roles of flavoproteins in molecular cell biology: blue-light active flavoproteins studied by electron paramagnetic resonance.

    Science.gov (United States)

    Schleicher, Erik; Bittl, Robert; Weber, Stefan

    2009-08-01

    Exploring enzymatic mechanisms at a molecular level is one of the major challenges in modern biophysics. Based on enzyme structure data, as obtained by X-ray crystallography or NMR spectroscopy, one can suggest how substrates and products bind for catalysis. However, from the 3D structure alone it is very rarely possible to identify how intermediates are formed and how they are interconverted. Molecular spectroscopy can provide such information and thus supplement our knowledge on the specific enzymatic reaction under consideration. In the case of enzymatic processes in which paramagnetic molecules play a role, EPR and related methods such as electron-nuclear double resonance (ENDOR) are powerful techniques to unravel important details, e.g. the electronic structure or the protonation state of the intermediate(s) carrying (the) unpaired electron spin(s). Here, we review recent EPR/ENDOR studies of blue-light active flavoproteins with emphasis on photolyases that catalyze the enzymatic repair of UV damaged DNA, and on cryptochrome blue-light photoreceptors that act in several species as central components of the circadian clock.

  8. Primary photophysics of the FMN binding LOV2 domain of the plant blue light receptor phototropin of Avena sativa

    Science.gov (United States)

    Schüttrigkeit, Tanja A.; Kompa, Christian K.; Salomon, Michael; Rüdiger, Wolfhart; Michel-Beyerle, Maria E.

    2003-11-01

    The temporal evolution of the initially excited singlet state of flavine mononucleotide, which is the cofactor in the LOV2 domain of the blue photoreceptor phototropin, has been studied in picosecond time-resolved fluorescence and femtosecond time-resolved absorption experiments. In the LOV2-WT protein of Avena sativa singlet-triplet intersystem crossing proceeding within 2.3 ns is the primary process which increases the triplet yield by a factor of 1.23 as compared to a mutant where cysteine 39 is replaced by alanine. This flavin triplet state is responsible for the formation of a cysteinyl-flavin adduct which triggers the unique photocycle of the LOV2 domain and thus the sensoric function of the blue light receptor phototropin.

  9. Blue light-induced immunosuppression in Bactrocera dorsalis adults, as a carryover effect of larval exposure.

    Science.gov (United States)

    Tariq, K; Noor, M; Hori, M; Ali, A; Hussain, A; Peng, W; Chang, C-J; Zhang, H

    2017-05-09

    Detrimental effects of ultraviolet (UV) light on living organisms are well understood, little is known about the effects of blue light irradiation. Although a recent study revealed that blue light caused more harmful effects on insects than UV light and blue light irradiation killed insect pests of various orders including Diptera, the effects of blue light on physiology of insects are still largely unknown. Here we studied the effects of blue light irradiation on cuticular melanin in larval and the immune response in adult stage of Bactrocera dorsalis. We also evaluated the effects of blue light exposure in larval stage on various age and mass at metamorphosis and the mediatory role of cuticular melanin in carryover effects of larval stressors across metamorphosis. We found that larvae exposed to blue light decreased melanin contents in their exoskeleton with smaller mass and delayed metamorphosis than insects reared without blue light exposure. Across metamorphosis, lower melanotic encapsulation response and higher susceptibility to Beauveria bassiana was detected in adults that had been exposed to blue light at their larval stage, thereby constituting the first evidence that blue light impaired adult immune function in B. dorsalis as a carryover effect of larval exposure.

  10. Effects and Mechanism of Blue Light on Monascus in Liquid Fermentation

    Directory of Open Access Journals (Sweden)

    Xiaowei Zhang

    2017-03-01

    Full Text Available The effect of light on Monascus and the underlying mechanism have received a great deal of interest for the industrial application of Monascus pigments. In this study, we have examined the effects of blue light on the culture morphology, mycelium growth, pigments, and citrinin yield of Monascus in liquid-state and oscillation fermentation, and explored the mechanism at a physiological level. It was found that blue light affected the colony morphology, the composition (chitin content, and permeability of the Monascus mycelium cell wall in static liquid culture, which indicates blue light benefits pigments secreting from aerial mycelium to culture medium. In liquid oscillation fermentation, the yields of Monascus pigments in fermentation broth (darkness 1741 U/g, blue light 2206 U/g and mycelium (darkness 2442 U/g, blue light 1900 U/g cultured under blue light and darkness are different. The total pigments produced per gram of Monascus mycelium under blue light was also higher (4663 U/g than that in darkness (4352 U/g. However, the production of citrinin (88 μg/g under blue light was evidently lower than that in darkness (150 μg/g. According to the degradation of citrinin caused by blue light and hydrogen peroxide, it can be concluded that blue light could degrade citrinin and inhibit the catalase activity of Monascus mycelium, subsequently suppressing the decomposition of hydrogen peroxide, which is the active species that degrades citrinin.

  11. Effects and Mechanism of Blue Light on Monascus in Liquid Fermentation.

    Science.gov (United States)

    Zhang, Xiaowei; Liu, Wenqing; Chen, Xiying; Cai, Junhui; Wang, Changlu; He, Weiwei

    2017-03-01

    The effect of light on Monascus and the underlying mechanism have received a great deal of interest for the industrial application of Monascus pigments. In this study, we have examined the effects of blue light on the culture morphology, mycelium growth, pigments, and citrinin yield of Monascus in liquid-state and oscillation fermentation, and explored the mechanism at a physiological level. It was found that blue light affected the colony morphology, the composition (chitin content), and permeability of the Monascus mycelium cell wall in static liquid culture, which indicates blue light benefits pigments secreting from aerial mycelium to culture medium. In liquid oscillation fermentation, the yields of Monascus pigments in fermentation broth (darkness 1741 U/g, blue light 2206 U/g) and mycelium (darkness 2442 U/g, blue light 1900 U/g) cultured under blue light and darkness are different. The total pigments produced per gram of Monascus mycelium under blue light was also higher (4663 U/g) than that in darkness (4352 U/g). However, the production of citrinin (88 μg/g) under blue light was evidently lower than that in darkness (150 μg/g). According to the degradation of citrinin caused by blue light and hydrogen peroxide, it can be concluded that blue light could degrade citrinin and inhibit the catalase activity of Monascus mycelium, subsequently suppressing the decomposition of hydrogen peroxide, which is the active species that degrades citrinin.

  12. Nuclear kinesis, neurite sprouting and abnormal axonal projections of cone photoreceptors in the aged and AMD-afflicted human retina.

    Science.gov (United States)

    Pow, David V; Sullivan, Robert K P

    2007-05-01

    Tissues often respond to damage by recapitulating developmental programs. We have investigated whether anatomical signs of developmental recapitulation are evident in cone photoreceptors of the aged and AMD-afflicted human retina. Radial migration of cell nuclei mediated by microtubules is a characteristic feature of cells in the developing retina. Similarly, neurite outgrowth is a feature of developing neurons. We have examined whether nuclear kinesis and neurite outgrowth from cone photoreceptors is evident. Calbindin-positive cone photoreceptor nuclei are normally positioned as a single layer of somata at the outer border of the outer nuclear layer. In AMD-afflicted retinae, many nuclei are translocated, with some somata abutting the outer plexiform layer (OPL) and others outside the outer limiting membrane whilst many nuclei are present at intermediate levels. The axonal processes of many cones were also aberrant, displaying tortuous pathways as they projected to the OPL, with occasional evidence for bifurcation at points where the axon changed direction. We suggest that tangential extension of collateral neurites and the rapid retraction of the original process may give rise to the tortuous axonal projections observed. Since microtubules are key mediators of both neurite extension and nuclear kinesis we examined expression of microtubule associated protein 2 (MAP2) which is an important regulator of neurite extension. The strong expression of MAP2 observed in those cells with aberrant morphologies supports the notion that abnormal microtubule-mediated remodelling events are present in the AMD retina and to a lesser extent in normal aged retinas, allowing cone photoreceptors to recapitulate two key features of development.

  13. Human retinal disease from AIPL1 gene mutations: foveal cone loss with minimal macular photoreceptors and rod function remaining.

    Science.gov (United States)

    Jacobson, Samuel G; Cideciyan, Artur V; Aleman, Tomas S; Sumaroka, Alexander; Roman, Alejandro J; Swider, Malgorzata; Schwartz, Sharon B; Banin, Eyal; Stone, Edwin M

    2011-01-05

    To determine the human retinal phenotype caused by mutations in the gene encoding AIPL1 (Aryl hydrocarbon receptor-interacting protein-like 1) now that there are proof-of-concept results for gene therapy success in Aipl1-deficient mice. Leber congenital amaurosis (LCA) patients (n = 10) and one patient with a later-onset retinal degeneration (RD) and AIPL1 mutations were studied by ocular examination, retinal imaging, perimetry, full-field sensitivity testing, and pupillometry. The LCA patients had severe visual acuity loss early in life, nondetectable electroretinograms (ERGs), and little or no detectable visual fields. Hallmarks of retinal degeneration were present in a wide region, including the macula and midperiphery; there was some apparent peripheral retinal sparing. Cross-sectional imaging showed foveal cone photoreceptor loss with a ring of minimally preserved paracentral photoreceptor nuclear layer. Features of retinal remodeling were present eccentric to the region of detectable photoreceptors. Full-field sensitivity was reduced by at least 2 log units, and chromatic stimuli, by psychophysics and pupillometry, revealed retained but impaired rod function. The RD patient, examined serially over two decades (ages, 45-67 years), retained an ERG in the fifth decade of life with abnormal rod and cone signals; and there was progressive loss of central and peripheral function. AIPL1-LCA, unlike some other forms of LCA with equally severe visual disturbance, shows profound loss of foveal as well as extrafoveal photoreceptors. The more unusual late-onset and slower form of AIPL1 disease may be better suited to gene augmentation therapy and is worthy of detection and further study.

  14. Inactivation of Salmonella on tainted foods: using blue light to disinfect cucumbers and processed meat products.

    Science.gov (United States)

    Guffey, J Stephen; Payne, William C; Motts, Susan D; Towery, Pam; Hobson, Todd; Harrell, Grafton; Meurer, Logan; Lancaster, Kristoffer

    2016-11-01

    Foodborne illness resulting from infectious organisms occurring in vegetables and processed meat is a serious health concern in the United States. Improved and cost-effective techniques for disinfection are needed. Visible light in the blue range (405 nm) was administered to processed meat that had been inoculated with Escherichia coli. One application of light energy at doses of 10, 30, 60, and 100 J/cm(2) was applied, in vitro. In the case of vegetables contaminated with Salmonella (cucumbers), 464 nm light was used at 6, 12, and 18 J/cm(2). In both cases, after 20 hours of incubation, colony-forming units were counted and compared to controls to determine whether the light energy inhibited growth of E. coli or Salmonella. E. coli - 405 nm light at doses of 30, 60, and 100 J/cm(2) were all effective inhibitors of the organism. Kill rates of 75.61 - 96.34% were achieved. Salmonella - 464 nm light at doses of 6, 12, and 18 J/cm(2) produced significant inactivation of the organism. Kill rates of 80.23-100% were obtained. Blue light, delivered in the wavelength/dose combinations used in this study is an effective inhibitor of both E. coli and Salmonella on actual foodstuffs. Blue light should be considered as a potentially effective tool in the effort to protect humans from foodborne illnesses.

  15. Synthesis of quinoline based heterocyclic compounds for blue lighting application

    Science.gov (United States)

    Kumar, Vinod; Gohain, Mukut; Van Tonder, Johannes H.; Ponra, S.; Bezuindenhoudt, B. C. B.; Ntwaeaborwa, O. M.; Swart, H. C.

    2015-12-01

    2,4-Diphenylquinoline (DPQ), derivatives 6-chloro-2,4-diphenylquinoline (DPQ-Cl) and 4‧,6-dichloro-2,4-diphenylquinoline (DPQ-Cl2) were synthesized using a three-component domino reaction. The DPQ, DPQ-Cl and DPQ-Cl2 were characterized by nuclear magnetic resonance spectroscopy, scanning electron microscopy, thermogravimetric analysis (TGA). Fourier transformed infra-red spectroscopy, X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible (UV-vis) spectroscopy and photoluminescence spectroscopy. The TGA results showed that the DPQ was more thermally stable with respect to the DPQ-Cl and DPQ-Cl2. The synthesized organic phosphors showed bright emission in the blue region under an UV excitation wavelength of 325 nm with the power of 18 mW. These organic phosphors were found to be efficient candidate and may be used in organic blue light emitting devices.

  16. [Cataract extraction and blue light--impact on the retina].

    Science.gov (United States)

    Engelmann, K; Funk, R H

    2009-10-01

    This review focuses on the scientific background for the use of "yellow artificial lenses". We will address the fact that numerous basic scientific publications point to a rationale for this practice although it is often difficult to derive clear-cut evidence from clinical epidemiological studies for the preventive use of yellow artificial lenses. In the first part we refer to studies showing that especially the shortwave part of the visible spectrum of light can be harmful for the retina and optic nerve. For this, we have screened the literature for the major sources of radical production and for the targets of oxidative stress after impingement of "blue light" on the retina. Furthermore, we can show that many studies in cell and molecular biology, animal experiments and first clinical trials point to a preferential use of yellow-tinted lenses especially in the elderly and AMD patients.

  17. Blue light emission of porous silicon subjected to RTP treatments

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yi; YANG Deren; LIN Lei; QUE Duanlin

    2006-01-01

    Porous silicon samples were treated with the rapid thermal process (RTP) under different circumstances (N2, Ar, O2 and Air). Before and after treatments, the samples were checked by means of photoluminescence (PL) spectroscopy and Fourier transform infrared spectroscopy (FTIR). Four blue light emission peaks were found in the PL spectra of porous silicon samples subjected to the RTP treatments at temperatures above 400℃. The peak positions were found not to vary with the circumstances and temperatures of RTP treatments. It is considered that due to oxidation during the RTP treatments, the pole size of Si crystal in porous silicon decreased,resulting in the blue shift of light emission. Correlated with the Si crystal sizes discontinuous hypothesis and previous researchers' theory calculation, the PL peak positions did not vary with the RTP temperature and circumstances.

  18. Unequal allocation of excitation energy between photosystem II and I reduces cyanolichen photosynthesis in blue light.

    Science.gov (United States)

    Solhaug, Knut Asbjørn; Xie, Li; Gauslaa, Yngvar

    2014-08-01

    Photosynthesis was compared in two cyanobacterial lichens (Lobaria hallii and Peltigera praetextata) and two green algal lichens (Lobaria pulmonaria and Peltigera leucophlebia) exposed to red, green or blue light. Cyanolichens had substantially lower photosynthetic CO(2) uptake and O(2) evolution than the green algal lichens in blue light, but slightly higher photosynthesis in red and green light. The effective quantum yield of photosystem (PS) II (Φ(PSII)) decreased with increasing red and green light for all species, but in blue light this response occurred in green algal lichens only. Cyanolichen Φ(PSII) increased with increasing blue light at low irradiances, but decreased at stronger exposures. However, after adding red light the efficiency of blue light for photosynthetic O(2) evolution increased by 2.4 times. Because phycobilisomes associated with PSII have a low blue light absorption, our results are consistent with blue light absorption mainly by Chl in PSI. Thereby, unequal allocation of excitation energy between PSII and PSI results in low cyanolichen photosynthesis under blue light. This is new knowledge in the science of lichenology with important implications for e.g. the reliability of using Chl fluorometers with blue light for cyanolichens.

  19. Effects of the cryptochrome CryB from Rhodobacter sphaeroides on global gene expression in the dark or blue light or in the presence of singlet oxygen.

    Science.gov (United States)

    Frühwirth, Sebastian; Teich, Kristin; Klug, Gabriele

    2012-01-01

    Several regulators are controlling the formation of the photosynthetic apparatus in the facultatively photosynthetic bacterium Rhodobacter sphaeroides. Among the proteins affecting photosynthesis gene expression is the blue light photoreceptor cryptochrome CryB. This study addresses the effect of CryB on global gene expression. The data reveal that CryB does not only influence photosynthesis gene expression but also genes for the non-photosynthetic energy metabolism like citric acid cycle and oxidative phosphorylation. In addition several genes involved in RNA processing and in transcriptional regulation are affected by a cryB deletion. Although CryB was shown to undergo a photocycle it does not only affect gene expression in response to blue light illumination but also in response to singlet oxygen stress conditions. While there is a large overlap in these responses, some CryB-dependent effects are specific for blue-light or photooxidative stress. In addition to protein-coding genes some genes for sRNAs show CryB-dependent expression. These findings give new insight into the function of bacterial cryptochromes and demonstrate for the first time a function in the oxidative stress response.

  20. Effects of the cryptochrome CryB from Rhodobacter sphaeroides on global gene expression in the dark or blue light or in the presence of singlet oxygen.

    Directory of Open Access Journals (Sweden)

    Sebastian Frühwirth

    Full Text Available Several regulators are controlling the formation of the photosynthetic apparatus in the facultatively photosynthetic bacterium Rhodobacter sphaeroides. Among the proteins affecting photosynthesis gene expression is the blue light photoreceptor cryptochrome CryB. This study addresses the effect of CryB on global gene expression. The data reveal that CryB does not only influence photosynthesis gene expression but also genes for the non-photosynthetic energy metabolism like citric acid cycle and oxidative phosphorylation. In addition several genes involved in RNA processing and in transcriptional regulation are affected by a cryB deletion. Although CryB was shown to undergo a photocycle it does not only affect gene expression in response to blue light illumination but also in response to singlet oxygen stress conditions. While there is a large overlap in these responses, some CryB-dependent effects are specific for blue-light or photooxidative stress. In addition to protein-coding genes some genes for sRNAs show CryB-dependent expression. These findings give new insight into the function of bacterial cryptochromes and demonstrate for the first time a function in the oxidative stress response.

  1. Early changes in gene expression induced by blue light irradiation of A2E-laden retinal pigment epithelial cells

    DEFF Research Database (Denmark)

    van der Burght, Barbro W; Hansen, Morten; Olsen, Jørgen;

    2013-01-01

    Purpose:  Accumulation of bisretinoids as lipofuscin in retinal pigment epithelial (RPE) cells is implicated in the pathogenesis of some blinding diseases including age-related macular degeneration (AMD). To identify genes whose expression may change under conditions of bisretinoid accumulation, we...... investigated the differential gene expression in RPE cells that had accumulated the lipofuscin fluorophore A2E and were exposed to blue light (430 nm). Methods:  A2E-laden RPE cells were exposed to blue light (A2E/430 nm) at various time intervals. Cell death was quantified using Dead Red staining, and RNA...... levels for the entire genome was determined using DNA microarrays (Affymetrix GeneChip Human Genome 2.0 Plus). Array results for selected genes were confirmed by real-time reverse-transcriptase polymerase chain reaction. Results:  Principal component analysis revealed that the A2E-laden RPE cells...

  2. Stimulatory effects of blue light on the growth, monascin and ankaflavin production in Monascus.

    Science.gov (United States)

    Wang, Changlu; Chen, Di; Chen, Mianhua; Wang, Yurong; Li, Zhenjing; Li, Fengjuan

    2015-05-01

    Light is an important signal for fungi. We analyzed the influence of blue light of various intensities and illumination times on growth, monascin (MS) and ankaflavin (AK) biosyntheses in Monascus strain M9. Blue light changed the color of colonies. The colonies grown in the dark were orange, but turned pale when exposed to continuous blue light. MS production increased by 12.5, 27, and 14.5 % under blue light of 100 lux for 15 min/day, 100 lux for 30 min/day, and 200 lux for 15 min/day, respectively, compared to growth in the dark. AK production increased by 14.4, 22, and 13 % under the same condition. MS and AK production decreased when exposed to blue light of 300 and 450 lux. The expression of pigment biosynthetic genes were analyzed by real-time quantitative PCR and correlated with phenotypic production of MS and AK.

  3. Transcriptome Dynamics of Developing Photoreceptors in Three-Dimensional Retina Cultures Recapitulates Temporal Sequence of Human Cone and Rod Differentiation Revealing Cell Surface Markers and Gene Networks.

    Science.gov (United States)

    Kaewkhaw, Rossukon; Kaya, Koray Dogan; Brooks, Matthew; Homma, Kohei; Zou, Jizhong; Chaitankar, Vijender; Rao, Mahendra; Swaroop, Anand

    2015-12-01

    The derivation of three-dimensional (3D) stratified neural retina from pluripotent stem cells has permitted investigations of human photoreceptors. We have generated a H9 human embryonic stem cell subclone that carries a green fluorescent protein (GFP) reporter under the control of the promoter of cone-rod homeobox (CRX), an established marker of postmitotic photoreceptor precursors. The CRXp-GFP reporter replicates endogenous CRX expression in vitro when the H9 subclone is induced to form self-organizing 3D retina-like tissue. At day 37, CRX+ photoreceptors appear in the basal or middle part of neural retina and migrate to apical side by day 67. Temporal and spatial patterns of retinal cell type markers recapitulate the predicted sequence of development. Cone gene expression is concomitant with CRX, whereas rod differentiation factor neural retina leucine zipper protein (NRL) is first observed at day 67. At day 90, robust expression of NRL and its target nuclear receptor NR2E3 is evident in many CRX+ cells, while minimal S-opsin and no rhodopsin or L/M-opsin is present. The transcriptome profile, by RNA-seq, of developing human photoreceptors is remarkably concordant with mRNA and immunohistochemistry data available for human fetal retina although many targets of CRX, including phototransduction genes, exhibit a significant delay in expression. We report on temporal changes in gene signatures, including expression of cell surface markers and transcription factors; these expression changes should assist in isolation of photoreceptors at distinct stages of differentiation and in delineating coexpression networks. Our studies establish the first global expression database of developing human photoreceptors, providing a reference map for functional studies in retinal cultures.

  4. Stomatal Blue Light Response Is Present in Early Vascular Plants.

    Science.gov (United States)

    Doi, Michio; Kitagawa, Yuki; Shimazaki, Ken-ichiro

    2015-10-01

    Light is a major environmental factor required for stomatal opening. Blue light (BL) induces stomatal opening in higher plants as a signal under the photosynthetic active radiation. The stomatal BL response is not present in the fern species of Polypodiopsida. The acquisition of a stomatal BL response might provide competitive advantages in both the uptake of CO2 and prevention of water loss with the ability to rapidly open and close stomata. We surveyed the stomatal opening in response to strong red light (RL) and weak BL under the RL with gas exchange technique in a diverse selection of plant species from euphyllophytes, including spermatophytes and monilophytes, to lycophytes. We showed the presence of RL-induced stomatal opening in most of these species and found that the BL responses operated in all euphyllophytes except Polypodiopsida. We also confirmed that the stomatal opening in lycophytes, the early vascular plants, is driven by plasma membrane proton-translocating adenosine triphosphatase and K(+) accumulation in guard cells, which is the same mechanism operating in stomata of angiosperms. These results suggest that the early vascular plants respond to both RL and BL and actively regulate stomatal aperture. We also found three plant species that absolutely require BL for both stomatal opening and photosynthetic CO2 fixation, including a gymnosperm, C. revoluta, and the ferns Equisetum hyemale and Psilotum nudum.

  5. Blue light curing units--a dermatological hazard?

    Science.gov (United States)

    Chadwick, R G; Traynor, N; Moseley, H; Gibbs, N

    1994-01-08

    The setting reactions of a large number of dental materials are activated upon exposure to visible blue light emitted from a curing unit. Although the wavelength (lambda) from such devices is principally in the visible spectrum (lambda > 400 nm) a small amount of ultraviolet radiation (UV) is also present. Little attention has been paid to the consequences of such exposure upon the skin of dental surgeons' fingers. This investigation studied the level of UVA I (lambda = 340-400 nm) emitted by three commonly used polymerisation sources and assessed the level of protection afforded by six brands of surgical glove. The integrated irradiances of the Translux, Topaz T100 and Heliomat units in the UVA I range were 15861, 3611 and 305 mW/m2 respectively. For all gloves the mean % transmission, at lambda = 400 nm, was less than 4% with the exception of one brand where, in the stretched state, the level of transmission was 7%. It is concluded that the risk of initiating adverse dermatological consequences as a result of exposure to UVA I, emitted by light polymerisation units, is minimal in normal usage. The combined effects of exposure to radiation of this type and contamination of the fingers with quantities of irritant chemicals, such as found in many dental materials, are unknown. Due to the ability of the gloves to shield the skin from both chemicals and UVA I it is recommended that gloves are routinely worn for all light curing procedures.

  6. Antimicrobial blue light inactivation of Methicillin-resistant Staphylococcus aureus

    Science.gov (United States)

    Wang, Yucheng; Dai, Tianhong; Gu, Ying

    2016-10-01

    Background: With the increasing emergence of multidrug-resistant (MDR) bacterial strains, there is a pressing need for the development of alternative treatment for infections. Antimicrobial blue light (aBL) has provided a simple and effective approach. Methods: We first investigated the effectiveness of aBL (415 nm) inactivation of USA300 LAClux (a communityacquired Methicillin-resistant Staphylococcus aureus strain) both in the planktonic and biofilm forms. The survival of the bacteria in suspensions was determined by serial dilution and that of the biofilm-embedded bacteria was determined by bioluminescence quantification. Using a mouse model of thermal burn infected with USA300 LAClux, we further assessed the effectiveness of aBL for treating localized infections. Bioluminescence imaging was performed to monitor in real time bacterial viability in vivo. Results: In vitro study showed that, for the planktonic counterpart of the bacteria or the 24-h-old biofilms, an irradiance of 55 mW/cm2 for 60 min resulted in a 4.61 log10 or 2.56 log10 inactivation, respectively. In vivo study using infected mouse burns demonstrated that a 2.56-log10 inactivation was achieved after 100-mW/cm2 irradiation for 62 min. Conclusions: aBL is a potential alternative approach for treating Methicillin-resistant Staphylococcus aureus infections.

  7. Blue Light Phototherapy Kills Methycillin Resistant Staphylococcus Aureus (MRSA)

    Science.gov (United States)

    Enwemeka, Chukuka S.; Williams, Debora; Enwemeka, Sombiri K.; Hollosi, Steve; Yens, David

    2010-05-01

    Background: Methycillin resistant staphylococcus aureus (MRSA) bacteria continue to defy most available antibiotics. As a result infections with MRSA remain a growing public health concern. As a paradigm shift and a significant departure from the on-going trend to develop stronger drug-based therapies, we studied the effect of 405 nm and 470 nm wavelengths of blue light on two strains of MRSA—US-300 strain of CA-MRSA and the IS853 strain of HA-MRSA—in vitro. Methods: We cultured and plated each strain, following which bacteria colonies were irradiated with 0, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 25, 30, 35, 40, 45, 50, 55, or 60 Jcm-2 energy densities—just once. Specimens were incubated at 35° C for 24 h. Then, digital images obtained were quantified to obtain colony counts and the aggregate area occupied by bacteria colonies. Results: Each wavelength produced a statistically significant dose-dependent reduction in both the number and the aggregate area of colonies formed by each bacteria strain (PMRSA and CA-MRSA in vitro; raising the prospect that phototherapy may be an effective clinical tool in the on-going effort to stem MRSA infections.

  8. Enhanced functional integration of human photoreceptor precursors into human and rodent retina in an ex vivo retinal explant model system.

    Science.gov (United States)

    Yanai, Anat; Laver, Christopher R J; Gregory-Evans, Cheryl Y; Liu, Ran R; Gregory-Evans, Kevin

    2015-06-01

    Retinal disease is the major cause of irreversible blindness in developed countries. Transplantation of photoreceptor precursor cells (PPCs) derived from human embryonic stem cells (hESCs) is a promising and widely applicable approach for the treatment of these blinding conditions. Previously, it has been shown that after transplantation into the degenerating retina, the percentage of PPCs that undergo functional integration is low. The factors that inhibit PPC engraftment remain largely unknown, in part, because so many adverse factors could be at play during in vivo experiments. To advance our knowledge in overcoming potential adverse effects and optimize PPC transplantation, we have developed a novel ex vivo system. Harvested neural retina was placed directly on top of cultured retinal pigment epithelial (RPE) cells from a number of different sources. To mimic PPC transplantation into the subretinal space, hESC-derived PPCs were inserted between the retinal explant and underlying RPE. Explants cocultured with hESC-derived RPE maintained normal gross morphology and viability for up to 2 weeks, whereas the explants cultured on ARPE19 and RPE-J failed by 7 days. Furthermore, the proportion of PPCs expressing ribbon synapse-specific proteins BASSOON and RIBEYE was significantly higher when cocultured with hESC-derived RPE (20% and 10%, respectively), than when cocultured with ARPE19 (only 6% and 2%, respectively). In the presence of the synaptogenic factor thrombospondin-1 (TSP-1), the proportion of BASSOON-positive and RIBEYE-positive PPCs cocultured with hESC-derived RPE increased to ∼30% and 15%, respectively. These data demonstrate the utility of an ex vivo model system to define factors, such as TSP-1, which could influence integration efficiency in future in vivo experiments in models of retinal degeneration.

  9. Anion channels and the stimulation of anthocyanin accumulation by blue light in Arabidopsis seedlings

    Science.gov (United States)

    Noh, B.; Spalding, E. P.; Evans, M. H. (Principal Investigator)

    1998-01-01

    Activation of anion channels by blue light begins within seconds of irradiation in seedlings and is related to the ensuing growth inhibition. 5-Nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) is a potent, selective, and reversible blocker of these anion channels in Arabidopsis thaliana. Here we show that 20 microM NPPB blocked 72% of the blue-light-induced accumulation of anthocyanin pigments in seedlings. Feeding biosynthetic intermediates to wild-type and tt5 seedlings provided evidence that NPPB prevented blue light from up-regulating one or more steps between and including phenylalanine ammonia lyase and chalcone isomerase. NPPB was found to have no significant effect on the blue-light-induced increase in transcript levels of PAL1, CHS, CHI, or DFR, which are genes that encode anthocyanin-biosynthetic enzymes. Immunoblots revealed that NPPB also did not inhibit the accumulation of the chalcone synthase, chalcone isomerase, or flavanone-3-hydroxylase proteins. This is in contrast to the reduced anthocyanin accumulation displayed by a mutant lacking the HY4 blue-light receptor, as hy4 displayed reduced expression of the above enzymes. Taken together, the data indicate that blue light acting through HY4 leads to an increase in the amount of biosynthetic enzymes but blue light must also act through a separate, anion-channel-dependent system to create a fully functional biosynthetic pathway.

  10. Lutein: more than just a filter for blue light.

    Science.gov (United States)

    Kijlstra, Aize; Tian, Yuan; Kelly, Elton R; Berendschot, Tos T J M

    2012-07-01

    Lutein is concentrated in the primate retina, where together with zeaxanthin it forms the macular pigment. Traditionally lutein is characterized by its blue light filtering and anti-oxidant properties. Eliminating lutein from the diet of experimental animals results in early degenerative signs in the retina while patients with an acquired condition of macular pigment loss (Macular Telangiectasia) show serious visual handicap indicating the importance of macular pigment. Whether lutein intake reduces the risk of age related macular degeneration (AMD) or cataract formation is currently a strong matter of debate and abundant research is carried out to unravel the biological properties of the lutein molecule. SR-B1 has recently been identified as a lutein binding protein in the retina and this same receptor plays a role in the selective uptake in the gut. In the blood lutein is transported via high-density lipoproteins (HDL). Genes controlling SR-B1 and HDL levels predispose to AMD which supports the involvement of cholesterol/lutein transport pathways. Apart from beneficial effects of lutein intake on various visual function tests, recent findings show that lutein can affect immune responses and inflammation. Lutein diminishes the expression of various ocular inflammation models including endotoxin induced uveitis, laser induced choroidal neovascularization, streptozotocin induced diabetes and experimental retinal ischemia and reperfusion. In vitro studies show that lutein suppresses NF kappa-B activation as well as the expression of iNOS and COX-2. Since AMD has features of a chronic low-grade systemic inflammatory response, attention to the exact role of lutein in this disease has shifted from a local effect in the eye towards a possible systemic anti-inflammatory function.

  11. Blue Light and Ultraviolet Radiation Exposure from Infant Phototherapy Equipment.

    Science.gov (United States)

    Pinto, Iole; Bogi, Andrea; Picciolo, Francesco; Stacchini, Nicola; Buonocore, Giuseppe; Bellieni, Carlo V

    2015-01-01

    Phototherapy is the use of light for reducing the concentration of bilirubin in the body of infants. Although it has become a mainstay since its introduction in 1958, a better understanding of the efficacy and safety of phototherapy applications seems to be necessary for improved clinical practices and outcomes. This study was initiated to evaluate workers' exposure to Optical Radiation from different types of phototherapy devices in clinical use in Italy. During infant phototherapy the staff monitors babies periodically for around 10 min every hour, and fixation of the phototherapy beam light frequently occurs: almost all operators work within 30 cm of the phototherapy source during monitoring procedures, with most of them commonly working at ≤25 cm from the direct or reflected radiation beam. The results of this study suggest that there is a great variability in the spectral emission of equipments investigated, depending on the types of lamps used and some phototherapy equipment exposes operators to blue light photochemical retinal hazard. Some of the equipment investigated presents relevant spectral emission also in the UVA region. Taking into account that the exposure to UV in childhood has been established as an important contributing factor for melanoma risk in adults and considering the high susceptibility to UV-induced skin damage of the newborn, related to his pigmentary traits, the UV exposure of the infant during phototherapy should be "as low as reasonably achievable," considering that it is unnecessary to the therapy. It is recommended that special safety training be provided for the affected employees: in particular, protective eyewear can be necessary during newborn assistance activities carried out in proximity of some sources. The engineering design of phototherapy equipment can be optimized. Specific requirements for photobiological safety of lamps used in the phototherapy equipment should be defined in the safety product standard for such

  12. The effect of blue light on L-type calcium channel subunit mRNA expression of human retinal pigment epithelial cells cultured in vitro%蓝光照射对人视网膜色素上皮细胞L-型钙通道mRNA表达的影响

    Institute of Scientific and Technical Information of China (English)

    宫鑫; 蔡善君; 李海辉; 吕建平; 伍志鹏; 宿罡; 谢兵

    2013-01-01

    effect of blue light on mRNA expression of L-type calcium channel subtypes of human retinal pigment epithelial (RPE) cells in vitro.Methods The fourth-generation of human RPE cells were randomly divided into four groups including control group (no light group),light group,light + nifedipine group,and light + (-) BayK8644 group.The cells were exposed to blue light (2000± 500) lux for 6 hours,and then cultured for another 24 hours.Reverse transcription polymerase chain reaction real time (RT-PCR) and fluorescence quantitative PCR technologies were used to analyze mRNA expression of L-type calcium channel subunit of cardiac subtype (1C or CaV1.2),neuroendocrine subtype (1D or CaV1.3) and retinal subtypes (1F or CaV1.4) in each group.Results The length of PCR product of 1C,1D,1F subunit and-actin was 68,157,125 and 186 base pairs respectively.(1) 1C mRNA expression in light,light + nifedipine and light + (-) BayK8644 group was higher than that in control group,the difference was statistically significant (P<0.05).1C mRNA expression in light + nifedipine group and light + (-) BayK8644 group was higher than in light group (P<0.05).1C mRNA expression in light + (-) BayK8644 group was higher than that in light + nifedipine group (P< 0.05).(2)Comparing with control group,1D mRNA expression was higher in light,light +nifedipine and light +(-) BayK8644 group,the difference was statistically significant (P<0.05).Light + (-) BayK8644 group was higher than light group and light + nifedipine group (P<0.05),light group and the light +nifedipine group was not statistically significant (P>0.05).(3) 1F mRNA expression in light,light +nifedipine and light + (-) BayK8644 group was higher than those in control group,there was statistically significant (P<0.05),light +nifedipine group and light + (-) BayK8644 group was higher than light group (P<0.05),light + nifedipine group and the light + (-) BayK8644 group was not statistically significant (P>0.05).Conclusions The human

  13. Directional migration of cancer cells induced by a blue light intensity gradient.

    Science.gov (United States)

    Lan, Chien-Chih; Lu, Eugene Youjhen; Pan, Huei-Jyuan; Lee, Chau-Hwang

    2015-07-01

    We used a spatial light modulator to project an optical micropattern of 473 nm light with a quartic intensity gradient on a single lung cancer cell. We observed that the intracellular amounts of reactive oxygen species (ROS) of the cancer cells were proportional to the intensity of the blue light, and the blue light intensity gradients could drive directional cell migration. This optically induced directional cell migration was inhibited by a ROS scavenger in the culture medium in a dose-dependent manner. In contrast, the ROS levels in fibroblasts were saturated by the blue light at low intensity and therefore the fibroblasts did not exhibit directional migration in the intensity gradient.

  14. Programming Retinal Stem Cells into Cone Photoreceptors

    Science.gov (United States)

    2015-12-01

    this grant, we sought to investigate the mechanisms that regulate the earliest events in cone photoreceptor development and to exploit this knowledge...the mRNA for three transcription factors promoted cone photoreceptor formation in retinal stem cells derived from human embryonic stem cells. These...reverse vision loss. 15. SUBJECT TERMS Cone photoreceptor, retina, retinal stem cell, Otx2, Onecut1, Blimp1, RNA-seq., transcription factors, and

  15. Probing entrainment of Ostreococcus tauri circadian clock by green and blue light through a mathematical modeling approach.

    Science.gov (United States)

    Thommen, Quentin; Pfeuty, Benjamin; Schatt, Philippe; Bijoux, Amandine; Bouget, François-Yves; Lefranc, Marc

    2015-01-01

    Most organisms anticipate daily environmental variations and orchestrate cellular functions thanks to a circadian clock which entrains robustly to the day/night cycle, despite fluctuations in light intensity due to weather or seasonal variations. Marine organisms are also subjected to fluctuations in light spectral composition as their depth varies, due to differential absorption of different wavelengths by sea water. Studying how light input pathways contribute to circadian clock robustness is therefore important. Ostreococcus tauri, a unicellular picoplanktonic marine green alga with low genomic complexity and simple cellular organization, has become a promising model organism for systems biology. Functional and modeling approaches have shown that a core circadian oscillator based on orthologs of Arabidopsis TOC1 and CCA1 clock genes accounts for most experimental data acquired under a wide range of conditions. Some evidence points at putative light input pathway(s) consisting of a two-component signaling system (TCS) controlled by the only two histidine kinases (HK) of O. tauri. LOV-HK is a blue light photoreceptor under circadian control, that is required for circadian clock function. An involvement of Rhodopsin-HK (Rhod-HK) is also conceivable since rhodopsin photoreceptors mediate blue to green light input in animal circadian clocks. Here, we probe the role of LOV-HK and Rhod-HK in mediating light input to the TOC1-CCA1 oscillator using a mathematical model incorporating the TCS hypothesis. This model agrees with clock gene expression time series representative of multiple environmental conditions in blue or green light, characterizing entrainment by light/dark cycles, free-running in constant light, and resetting. Experimental and theoretical results indicate that both blue and green light can reset O. tauri circadian clock. Moreover, our mathematical analysis suggests that Rhod-HK is a blue-green light receptor and drives the clock together with LOV-HK.

  16. Primary events in the blue light sensor plant cryptochrome: intraprotein electron and proton transfer revealed by femtosecond spectroscopy.

    Science.gov (United States)

    Immeln, Dominik; Weigel, Alexander; Kottke, Tilman; Pérez Lustres, J Luis

    2012-08-01

    Photoreceptors are chromoproteins that undergo fast conversion from dark to signaling states upon light absorption by the chromophore. The signaling state starts signal transduction in vivo and elicits a biological response. Therefore, photoreceptors are ideally suited for analysis of protein activation by time-resolved spectroscopy. We focus on plant cryptochromes which are blue light sensors regulating the development and daily rhythm of plants. The signaling state of these flavoproteins is the neutral radical of the flavin chromophore. It forms on the microsecond time scale after light absorption by the oxidized state. We apply here femtosecond broad-band transient absorption to early stages of signaling-state formation in a plant cryptochrome from the green alga Chlamydomonas reinhardtii. Transient spectra show (i) subpicosecond decay of flavin-stimulated emission and (ii) further decay of signal until 100 ps delay with nearly constant spectral shape. The first decay (i) monitors electron transfer from a nearby tryptophan to the flavin and occurs with a time constant of τ(ET) = 0.4 ps. The second decay (ii) is analyzed by spectral decomposition and occurs with a characteristic time constant τ(1) = 31 ps. We reason that hole transport through a tryptophan triad to the protein surface and partial deprotonation of tryptophan cation radical hide behind τ(1). These processes are probably governed by vibrational cooling. Spectral decomposition is used together with anisotropy to obtain the relative orientation of flavin and the final electron donor. This narrows the number of possible electron donors down to two tryptophans. Structural analysis suggests that a set of histidines surrounding the terminal tryptophan may act as proton acceptor and thereby stabilize the radical pair on a 100 ps time scale.

  17. A Dynamic Model for Prediction of Psoriasis Management by Blue Light Irradiation

    Science.gov (United States)

    Félix Garza, Zandra C.; Liebmann, Joerg; Born, Matthias; Hilbers, Peter A. J.; van Riel, Natal A. W.

    2017-01-01

    Clinical investigations prove that blue light irradiation reduces the severity of psoriasis vulgaris. Nevertheless, the mechanisms involved in the management of this condition remain poorly defined. Despite the encouraging results of the clinical studies, no clear guidelines are specified in the literature for the irradiation scheme regime of blue light-based therapy for psoriasis. We investigated the underlying mechanism of blue light irradiation of psoriatic skin, and tested the hypothesis that regulation of proliferation is a key process. We implemented a mechanistic model of cellular epidermal dynamics to analyze whether a temporary decrease of keratinocytes hyper-proliferation can explain the outcome of phototherapy with blue light. Our results suggest that the main effect of blue light on keratinocytes impacts the proliferative cells. They show that the decrease in the keratinocytes proliferative capacity is sufficient to induce a transient decrease in the severity of psoriasis. To study the impact of the therapeutic regime on the efficacy of psoriasis treatment, we performed simulations for different combinations of the treatment parameters, i.e., length of treatment, fluence (also referred to as dose), and intensity. These simulations indicate that high efficacy is achieved by regimes with long duration and high fluence levels, regardless of the chosen intensity. Our modeling approach constitutes a framework for testing diverse hypotheses on the underlying mechanism of blue light-based phototherapy, and for designing effective strategies for the treatment of psoriasis. PMID:28184200

  18. Downregulation of the Canonical WNT Signaling Pathway by TGFβ1 Inhibits Photoreceptor Differentiation of Adult Human Müller Glia with Stem Cell Characteristics

    Science.gov (United States)

    Angbohang, Angshumonik; Wu, Na; Charalambous, Thalis; Eastlake, Karen; Lei, Yuan; Kim, Yung Su; Sun, Xinghuai H.

    2016-01-01

    Müller glia are responsible for the retina regeneration observed in zebrafish. Although the human retina harbors Müller glia with stem cell characteristics, there is no evidence that they regenerate the retina after disease or injury. Transforming growth factor-β (TGFβ) and Wnt signaling regulate retinal neurogenesis and inflammation, but their roles in the neural differentiation of human Müller stem cells (hMSC) are not known. We examined hMSC lines in vitro for the expression of various Wnt signaling components and for their modulation by TGFβ1, as well as the effect of this cytokine on the photoreceptor differentiation of these cells. Culture of hMSC with a combination of factors that induce photoreceptor differentiation of hMSC (FGF2, taurine, retinoic acid, and insulin-like growth factor type1; FTRI), markedly upregulated the expression of components of the canonical Wnt signaling pathway, including WNT2B, DKK1, and active β-CATENIN. Although FTRI did not modify mRNA expression of WNT5B, a component of the noncanonical/planar cell polarity Wnt pathway, it upregulated its secretion. Furthermore, TGFβ1 not only decreased WNT2B expression, but also inhibited FTRI-induced photoreceptor differentiation of hMSC, as determined by expression of the photoreceptor markers NR2E3, RHODOPSIN, and RECOVERIN. Inhibition of TGFβ1 signaling by an ALK5 inhibitor prevented TGFβ1-induced changes in the expression of the two Wnt ligands examined. More importantly, inhibition of the canonical WNT signaling by XAV-939 prevented FTRI-induced photoreceptor differentiation. These observations suggest that TGFβ may play a key role in preventing neural differentiation of hMSC and may constitute a potential target for induction of endogenous regeneration of the human retina. PMID:26456050

  19. Blue light dose–responses of leaf photosynthesis, morphology, and chemical composition of Cucumis sativus grown under different combinations of red and blue light

    NARCIS (Netherlands)

    Hogewoning, S.W.; Trouwborst, G.; Maljaars, H.; Poorter, H.; Ieperen, van W.; Harbinson, J.

    2010-01-01

    The blue part of the light spectrum has been associated with leaf characteristics which also develop under high irradiances. In this study blue light dose–response curves were made for the photosynthetic properties and related developmental characteristics of cucumber leaves that were grown at an eq

  20. Different blue-light requirement for the accumulation of transcripts from nuclear genes for thylakoid proteins in Nicotiana tabacum and Lycopersicon esculentum.

    Science.gov (United States)

    Palomares, R; Herrmann, R G; Oelmüller, R

    1991-11-01

    We have isolated recombinant lambda gt11 phages which carry cDNA clones for the major light-harvesting chlorophyll a/b-binding proteins of photosystem I (LHCPI) and II (LHCPII), subunit II of photosystem I, a chlorophyll a/b-binding protein of photosystem II (CP24), the Rieske iron-sulphur protein of the cytochrome b6/f complex, and the 33, 23 and 16 kDa proteins of the water-oxidizing complex of photosystem II from Nicotiana tabacum. The nucleotide sequences of cDNA clones encoding the precursors for LHCPI and the FeS protein are presented. If tobacco or tomato seedlings, or seedlings of a phytochrome-deficient aurea mutant of tomato which lacks more than 95% of the phytochrome of the isogenic wild type, are kept in blue light, the transcript level of each of these genes is higher than in seedlings grown in red light suggesting the involvement of a blue-UVA-light photoreceptor. In the case of LHCPI, a 1 min blue-light pulse applied to red-light-grown seedlings is sufficient to increase the transcript levels to those present in blue-light-grown seedlings, whereas almost no increase is observed for transcripts encoding the FeS and 33 kDa proteins. If dark-grown tomato seedlings receive a single far-red-light pulse, significant stimulation is detected for LHCPI transcripts, whereas transcripts encoding the FeS and 33 kDa proteins are not stimulated. It is concluded that the lower light requirement for the increase in the LHCPI transcript level is not specific for one of the light-dependent signal transduction chains.

  1. Photo Inactivation of Streptococcus mutans Biofilm by Violet-Blue light.

    Science.gov (United States)

    Gomez, Grace F; Huang, Ruijie; MacPherson, Meoghan; Ferreira Zandona, Andrea G; Gregory, Richard L

    2016-09-01

    Among various preventive approaches, non-invasive phototherapy/photodynamic therapy is one of the methods used to control oral biofilm. Studies indicate that light at specific wavelengths has a potent antibacterial effect. The objective of this study was to determine the effectiveness of violet-blue light at 380-440 nm to inhibit biofilm formation of Streptococcus mutans or kill S. mutans. S. mutans UA159 biofilm cells were grown for 12-16 h in 96-well flat-bottom microtiter plates using tryptic soy broth (TSB) or TSB with 1 % sucrose (TSBS). Biofilm was irradiated with violet-blue light for 5 min. After exposure, plates were re-incubated at 37 °C for either 2 or 6 h to allow the bacteria to recover. A crystal violet biofilm assay was used to determine relative densities of the biofilm cells grown in TSB, but not in TSBS, exposed to violet-blue light. The results indicated a statistically significant (P < 0.05) decrease compared to the non-treated groups after the 2 or 6 h recovery period. Growth rates of planktonic and biofilm cells indicated a significant reduction in the growth rate of the violet-blue light-treated groups grown in TSB and TSBS. Biofilm viability assays confirmed a statistically significant difference between violet-blue light-treated and non-treated groups in TSB and TSBS. Visible violet-blue light of the electromagnetic spectrum has the ability to inhibit S. mutans growth and reduce the formation of S. mutans biofilm. This in vitro study demonstrated that violet-blue light has the capacity to inhibit S. mutans biofilm formation. Potential clinical applications of light therapy in the future remain bright in preventing the development and progression of dental caries.

  2. Inhibitory effect of blue light emitting diode on migration and invasion of cancer cells.

    Science.gov (United States)

    Oh, Phil-Sun; Kim, Hyun-Soo; Kim, Eun-Mi; Hwang, Hyosook; Ryu, Hyang Hwa; Lim, SeokTae; Sohn, Myung-Hee; Jeong, Hwan-Jeong

    2017-12-01

    The aim of this study was to determine the effects and molecular mechanism of blue light emitting diode (LED) in tumor cells. A migration and invasion assay for the metastatic behavior of mouse colon cancer CT-26 and human fibrosarcoma HT-1080 cells was performed. Cancer cell migration-related proteins were identified by obtaining a 2-dimensional gel electrophoresis (2-DE) in total cellular protein profile of blue LED-irradiated cancer cells, followed by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis of proteins. Protein levels were examined by immunoblotting. Irradiation with blue LED inhibited CT-26 and HT-1080 cell migration and invasion. The anti-metastatic effects of blue LED irradiation were associated with inhibition of matrix metalloproteinase (MMP)-2 and MMP-9 expression. P38 MAPK phosphorylation was increased in blue LED-irradiated CT-26 and HT-1080 cells, but was inhibited after pretreatment with SB203580, a specific inhibitor of p38 MAPK. Inhibition of p38 MAPK phosphorylation by SB203580 treatment increased number of migratory cancer cells in CT-26 and HT-1080 cells, indicating that blue LED irradiation inhibited cancer cell migration via phosphorylation of p38 MAPK. Additionally blue LED irradiation of mice injected with CT-26 cells expressing luciferase decreased early stage lung metastasis compared to untreated control mice. These results indicate that blue LED irradiation inhibits cancer cell migration and invasion in vitro and in vivo. © 2017 Wiley Periodicals, Inc.

  3. Intracellular reactive oxygen species in monocytes generated by photosensitive chromophores activated with blue light.

    Science.gov (United States)

    Bouillaguet, Serge; Owen, Brandi; Wataha, John C; Campo, Marino A; Lange, Norbert; Schrenzel, Jacques

    2008-08-01

    Disinfection of the tooth pulp-canal system is imperative to successful endodontic therapy. Yet, studies suggest that 30-50% of current endodontic treatments fail from residual bacterial infection. Photodynamic therapy using red-light chromophores (630 nm) to induce antimicrobial death mediated by generated reactive oxygen species (ROS) has been reported, but red-light also may thermally damage resident tissues. In the current study, we tested the hypothesis that several blue light chromophores (380-500 nm) generate intracellular reactive oxygen species but are not cytotoxic to mammalian cells. THP1 monocytes were exposed to 10 microM of four chromophores (chlorin e6, pheophorbide-a, pheophorbide-a-PLL, and riboflavin) for 30 min before activation with blue light (27J/cm(2), 60s). After activation, intracellular ROS were measured using a dihydrofluorescein diacetate technique, and cytotoxicity was determined by measuring mitochondrial activity with the MTT method. All photosensitizers produced intracellular ROS levels that were dependent on both the presence of the photosensitizer and blue light exposure. Riboflavin and pheophorbide-a-PLL produced the highest levels of ROS. Photosensitizers except riboflavin exhibited cytotoxicity above 10 microM, and all except pheophorbide-a-PLL were more cytotoxic after blue light irradiation. The current study demonstrated the possible utility of blue light chromophores as producers of ROS that would be useful for endodontic disinfection.

  4. Mechanism of rapid suppression of cell expansion in cucumber hypocotyls after blue-light irradiation

    Science.gov (United States)

    Cosgrove, D. J.

    1988-01-01

    Rapid suppression of hypocotyl elongation by blue light in cucumber (Cucumis sativus L.) was studied to examine possible hydraulic and wall changes responsible for diminished growth. Cell-sap osmotic pressure, measured by vapor-pressure osmometry, was not decreased by blue light; turgor pressure, measured by the pressure-probe technique, remained constant during the growth inhibition; and stem hydraulic conductance, measured by dynamic and static methods, was likewise unaffected by blue light. Wall yielding properties were assessed by the pressure-block technique for in-vivo stress relaxation. Blue light reduced the initial rate of relaxation by 77%, but had little effect on the final amount of relaxation. The results demonstrate that blue irradiation acts to decrease the wall yielding coefficient, but not the yield threshold. Stress-strain (Instron) analysis showed that irradiation of the seedlings had little effect on the mechanical extensibilities of the isolated wall. The results indicate that blue light can reduce cell-wall loosening without affecting bulk viscoelastic properties, and indicate a chemorheological mechanism of cell-wall expansion.

  5. Commercial preslaughter blue light ambience for controlling broiler stress and meat qualities

    Directory of Open Access Journals (Sweden)

    Claudia Freitas Barbosa

    2013-10-01

    Full Text Available The objective of this work was to study the effect of blue light diffuser on the broiler stress control by measuring the occurrence of PSE meat just before slaughtering. Birds were divided into the following two groups before slaughter at the point of being hung on shackles: broiler group under low intensity blue light ambience (475, 17-20 lx and control group under white light (550-650nm, 321-332 lx. Birds' stressful conditions were measured by the occurrence of PSE meat. Breast fillets were classified as PSE meat based on pH ( 53.0. The fillet samples in the control group had the following characteristics: pHu=5.77, L* = 54.26 and b*= 6.27. The fillet samples from birds under blue light ambience had the following characteristics: pHu=5.81, L* = 52.86 and b* = 5.22 (p < 0.05. These results revealed that the treatment of blue light ambience just before slaughtering contributed to the alleviation of ante mortem stress of the birds, which was observed by a 14% decrease in the occurrence of PSE meat. Exposure to blue light just before slaughtering was shown to have potential to be used in modern slaughterhouses to offer a comfortable atmosphere, thereby maintaining breast meat quality.

  6. Modulatory Effect of Monochromatic Blue Light on Heat Stress Response in Commercial Broilers

    Science.gov (United States)

    Abdo, Safaa E.; Mahmoud, Shawky

    2017-01-01

    In a novel approach, monochromatic blue light was used to investigate its modulatory effect on heat stress biomarkers in two commercial broiler strains (Ross 308 and Cobb 500). At 21 days old, birds were divided into four groups including one group housed in white light, a second group exposed to blue light, a 3rd group exposed to white light + heat stress, and a 4th group exposed to blue light + heat stress. Heat treatment at 33°C lasted for five h for four successive days. Exposure to blue light during heat stress reduced MDA concentration and enhanced SOD and CAT enzyme activities as well as modulated their gene expression. Blue light also reduced the degenerative changes that occurred in the liver tissue as a result of heat stress. It regulated, though variably, liver HSP70, HSP90, HSF1, and HSF3 gene expression among Ross and Cobb chickens. Moreover, the Cobb strain showed better performance than Ross manifested by a significant reduction of rectal temperature in the case of H + B. Furthermore, a significant linear relationship was found between the lowered rectal temperature and the expression of all HSP genes. Generally, the performance of both strains by most assessed parameters under heat stress is improved when using blue light. PMID:28698764

  7. Direct cell fate conversion of human somatic stem cells into cone and rod photoreceptor-like cells by inhibition of microRNA-203

    OpenAIRE

    Choi, Soon Won; Shin, Ji-Hee; Kim, Jae-Jun; Shin, Tae-Hoon; Seo, Yoojin; Kim, Hyung-Sik; Kang, Kyung-Sun

    2016-01-01

    Stem cell-based photoreceptor differentiation strategies have been the recent focus of therapies for retinal degenerative diseases. Previous studies utilized embryonic stem (ES) cells and neural retina differentiation cocktails, including DKK1 and Noggin. Here, we show a novel microRNA-mediated strategy of retina differentiation from somatic stem cells, which are potential allogeneic cell sources. Human amniotic epithelial stem cells (AESCs) and umbilical cord blood-derived mesenchymal stem c...

  8. Treatment of actinic cheilitis by photodynamic therapy with 5-aminolevulinic acid and blue light activation.

    Science.gov (United States)

    Zaiac, Martin; Clement, Annabelle

    2011-11-01

    Actinic cheilitis (AC), a common disorder of the lower lip, should be treated early to prevent progression to invasive squamous cell carcinoma. This study evaluated the safety and efficacy of photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) activated by blue light for the treatment of AC. Fifteen patients with clinically evident or biopsy-proven AC received two treatments with ALA PDT with blue light activation. Treatments were spaced three to five weeks apart. Most patients achieved 65% to 75% clearance three to five weeks after the first treatment and all achieved more than 75% clearance one month after the second treatment. Three patients achieved complete clearance. Pain and burning during irradiation were absent or mild. All patients said they would repeat the procedure. ALA PDT with 417 nm blue light is a promising option for the treatment of AC of the lower lip.

  9. Blue light-dependent nuclear positioning in Arabidopsis thaliana leaf cells.

    Science.gov (United States)

    Iwabuchi, Kosei; Sakai, Tatsuya; Takagi, Shingo

    2007-09-01

    The plant nucleus changes its intracellular position not only upon cell division and cell growth but also in response to environmental stimuli such as light. We found that the nucleus takes different intracellular positions depending on blue light in Arabidopsis thaliana leaf cells. Under dark conditions, nuclei in mesophyll cells were positioned at the center of the bottom of cells (dark position). Under blue light at 100 mumol m(-2) s(-1), in contrast, nuclei were located along the anticlinal walls (light position). The nuclear positioning from the dark position to the light position was fully induced within a few hours of blue light illumination, and it was a reversible response. The response was also observed in epidermal cells, which have no chloroplasts, suggesting that the nucleus has the potential actively to change its position without chloroplasts. Light-dependent nuclear positioning was induced specifically by blue light at >50 mumol m(-2) s(-1). Furthermore, the response to blue light was induced in phot1 but not in phot2 and phot1phot2 mutants. Unexpectedly, we also found that nuclei as well as chloroplasts in phot2 and phot1phot2 mutants took unusual intracellular positions under both dark and light conditions. The lack of the response and the unusual positioning of nuclei and chloroplasts in the phot2 mutant were recovered by externally introducing the PHOT2 gene into the mutant. These results indicate that phot2 mediates the blue light-dependent nuclear positioning and the proper positioning of nuclei and chloroplasts. This is the first characterization of light-dependent nuclear positioning in spermatophytes.

  10. Clinical Efficacy of Self-applied Blue Light Therapy for Mild-to-Moderate Facial Acne.

    Science.gov (United States)

    Gold, Michael H; Andriessen, Anneke; Biron, Julie; Andriessen, Hinke

    2009-03-01

    This study was an evaluation of the performance of self-applied, blue light, light-emitting diode therapy in the treatment of mild-to-moderate inflammatory acne on the face, concerning: 1) time to improvement and/or resolution of the number of blemishes and lesions on the face; 2) quality of skin condition; 3) occurrence and count of the number of new blemishes and lesions; and 4) ease of product use; patient comfort, wellbeing, and satisfaction during the treatment period; and safety of treatment. Subjects (N=21) were included according to the inclusion/exclusion criteria and after they had given informed consent. The blue light treatment was conducted over an eight-week period. For study data management and analysis, SPSS 16.0 statistical software was used. Data management and analysis was performed independently using, where appropriate, ANOVA, student t-test, and Mann-Whitney test for N=20. Tests were carried out at the five-percent significance level. The confidence interval was 95 percent. Twenty-one subjects concluded the study (18/21 were female and 3/21 were male). Upon the first outbreak of acne, subjects had a mean age of 15 years (range 8-28 years), and 19 subjects had mild-to-moderate acne for a mean duration of 13.1 years. During the study period with self-applied blue light treatment, the total number of comedones on the face had significantly reduced for the assessment at Day 7 (pconfidence in using the self-applied blue light without the supervision of a doctor. Regarding previous treatments, subjects expressed dissatisfaction and considered self-applied blue light treatment to be better for their condition. Self-applied blue light treatment was reported to be easy and safe to use.

  11. Discussion on Photoreceptor for Negative Phototropism in Rice Roots

    Institute of Scientific and Technical Information of China (English)

    WANG Yue-xia; WANG Zhong; SUO Biao; GU Yun-jie; WANG Hui-hui; CHEN Yong-hui; DAI Yun-xia

    2007-01-01

    To properly explore the photoreceptor for the negative phototropism in rice (Oryza sativa L.) root, lights with different wavelengths were applied to investigate the effect of light quality on phototropic bending. The phototropic bending could be induced prominently by blue/ultraviolet light, whereas not by red or far-red light. The absorption spectrum of the extracted solution from rice root cap had two peaks at 350 nm and 450 nm, respectively, and the molecular weight of the 120 kD protein in the root cap under unilateral light was larger than that under the dark. It suggested that the blue light receptor might be the photoreceptor for the negative phototropism in rice root.

  12. Discussion on Photoreceptor for Negative Phototropism in Rice Roots

    Directory of Open Access Journals (Sweden)

    Yue-xia WANG

    2007-12-01

    Full Text Available To properly explore the photoreceptor for the negative phototropism in rice (Oryza sativa L. root, lights with different wavelengths were applied to investigate the effect of light quality on phototropic bending. The phototropic bending could be induced prominently by blue/ultraviolet light, whereas not by red or far-red light. The absorption spectrum of the extracted solution from rice root cap had two peaks at 350 nm and 450 nm, respectively, and the molecular weight of the 120 kD protein in the root cap under unilateral light was larger than that under the dark. It suggested that the blue light receptor might be the photoreceptor for the negative phototropism in rice root.

  13. Effects of smartphone use with and without blue light at night in healthy adults: A randomized, double-blind, cross-over, placebo-controlled comparison.

    Science.gov (United States)

    Heo, Jung-Yoon; Kim, Kiwon; Fava, Maurizio; Mischoulon, David; Papakostas, George I; Kim, Min-Ji; Kim, Dong Jun; Chang, Kyung-Ah Judy; Oh, Yunhye; Yu, Bum-Hee; Jeon, Hong Jin

    2017-04-01

    Smartphones deliver light to users through Light Emitting Diode (LED) displays. Blue light is the most potent wavelength for sleep and mood. This study investigated the immediate effects of smartphone blue light LED on humans at night. We investigated changes in serum melatonin levels, cortisol levels, body temperature, and psychiatric measures with a randomized, double-blind, cross-over, placebo-controlled design of two 3-day admissions. Each subject played smartphone games with either conventional LED or suppressed blue light from 7:30 to 10:00PM (150 min). Then, they were readmitted and conducted the same procedure with the other type of smartphone. Serum melatonin levels were measured in 60-min intervals before, during and after use of the smartphones. Serum cortisol levels and body temperature were monitored every 120 min. The Profile of Mood States (POMS), Epworth Sleepiness Scale (ESS), Fatigue Severity Scale (FSS), and auditory and visual Continuous Performance Tests (CPTs) were administered. Among the 22 participants who were each admitted twice, use of blue light smartphones was associated with significantly decreased sleepiness (Cohen's d = 0.49, Z = 43.50, p = 0.04) and confusion-bewilderment (Cohen's d = 0.53, Z = 39.00, p = 0.02), and increased commission error (Cohen's d = -0.59, t = -2.64, p = 0.02). Also, users of blue light smartphones experienced a longer time to reach dim light melatonin onset 50% (2.94 vs. 2.70 h) and had increases in body temperature, serum melatonin levels, and cortisol levels, although these changes were not statistically significant. Use of blue light LED smartphones at night may negatively influence sleep and commission errors, while it may not be enough to lead to significant changes in serum melatonin and cortisol levels. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. RNA-Seq reveals changes in the Staphylococcus aureus transcriptome following blue light illumination.

    Science.gov (United States)

    Adair, Tamarah L; Drum, Bayless E

    2016-09-01

    In an effort to better understand the mechanism by which blue light inhibits the growth of Staphylococcus aureus in culture, a whole transcriptome analysis of S. aureus isolate BUSA2288 was performed using RNA-Seq to analyze the differential gene expression in response to blue light exposure. RNA was extracted from S. aureus cultures pooled from 24 1 ml well samples that were each illuminated with a dose of 250 J/cm(2) of 465 nm blue light and from control cultures grown in the dark. Complementary DNA libraries were generated from enriched mRNA samples and sequenced using the Illumina MiSeq Next Generation Sequencer. Here we report one type of analysis that identified 32 candidate genes for further investigation. Blue light has been shown to be bactericidal against S. aureus and is a potential alternative therapy for antibiotic resistant organisms. The mechanism for the inactivation of bacteria is hypothesized to involve reactive oxygen species. These RNA-Seq results provide data that may be used to test this hypothesis. The RNA-Seq data generated by these experiments is deposited in Gene Expression Omnibus (Gene accession GSE62055) and may be found at NCBI (http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE62055).

  15. Charge transport and recombination in polyspirobifluorene blue light-emitting diodes

    NARCIS (Netherlands)

    Nicolai, H.T.; Hof, A.; Oosthoek, J.L.M.; Blom, P.W.M.

    2011-01-01

    The charge transport in blue light-emitting polyspirobifluorene is investigated by both steady-state current-voltage measurements and transient electroluminescence. Both measurement techniques yield consistent results and show that the hole transport is space-charge limited. The electron current is

  16. Characterisation of blue-light stimulated luminescence components in different quartz samples: Implications for dose measurement

    DEFF Research Database (Denmark)

    Jain, M.; Murray, A.S.; Bøtter-Jensen, L.

    2003-01-01

    results from measurement of (a) sensitisation, (b) thermal stability, (c) recuperation, and (d) infrared response as a function of stimulation temperature from 3 different samples of sedimentary quartz selected on the basis of relative OSL contribution from different blue light stimulated linearly...

  17. Evidence of a Light-Sensing Role for Folate in Arabidopsis Cryptochrome Blue-Light Receptors

    Institute of Scientific and Technical Information of China (English)

    Nathalie Hoang; Jean-Pierre Bouly; Margaret Ahmad

    2008-01-01

    Arabidopsis cryptochromes cry1 and cry2 are blue-light signalling molecules with significant structural similarity to photolyases-a class of blue-light-sensing DNA repair enzymes. Like photolyases, purified plant cryptochromes have been shown to bind both flavin and pterin chromophores. The flavin functions as a light sensor and undergoes reduction in response to blue light that initiates the signalling cascade. However, the role of the pterin in plant cryptochromes has until now been unknown. Here, we show that the action spectrum for light-dependent degradation of cry2 has a significant peak of activity at 380 nm, consistent with absorption by a pterin cofactor. We further show that cry1 protein expressed in living insect cells responds with greater sensitivity to 380 nm light than to 450 nm, consistent with a light-harvesting antenna pigment that transfers excitation energy to the oxidized flavin of cry1. The pterin biosynthesis inhibitor DHAP selectively reduces cryptochrome responsivity at 380 nm but not 450 nm blue light in these cell cultures, indicating that the antenna pigment is a folate cofactor similar to that of photolyases.

  18. Reconsidering the effects of blue-light installation for prevention of railway suicides.

    Science.gov (United States)

    Ichikawa, Masao; Inada, Haruhiko; Kumeji, Minae

    2014-01-01

    A recent preliminary communication suggested that the calming effect of blue lights installed at the ends of railway platforms in Japan reduced suicides by 84%. This estimate is potentially misleading from an epidemiological point of view and is reconsidered in the present study. Governmental data listing all railway suicide attempts in Japan from April 2002 to March 2012 were used to investigate the proportion of suicide attempts within station premises, where blue lights are potentially installed, and at night, when they would be lit. For those suicide attempts within station premises, we also estimated the proportion that occurred at the ends of the platforms at night. Of 5841 total reported suicide attempts, 43% occurred within the station premises, 43% occurred at night (from 18:00 to 05:59), and 14% occurred both within the station premises and at night. Of the 2535 attempts within station premises, 32% occurred at night and 28% at most were at the end of a platform at night. The exact proportion of nighttime suicide attempts at the ends of railway platforms was not calculable. Nonetheless, the proportion of suicide attempts that is potentially preventable by blue lights should be less than our conservative estimate. The installation of blue lights on platforms, even were they to have some effect in preventing railway suicides at night, would have a much smaller impact than previously estimated. © 2013 Published by Elsevier B.V.

  19. Clinical efficacy of blue light full body irradiation as treatment option for severe atopic dermatitis.

    Directory of Open Access Journals (Sweden)

    Detlef Becker

    Full Text Available BACKGROUND: Therapy of atopic dermatitis (AD relies on immunosuppression and/or UV irradiation. Here, we assessed clinical efficacy and histopathological alterations induced by blue light-treatment of AD within an observational, non-interventional study. METHODOLOGY/PRINCIPAL FINDINGS: 36 patients with severe, chronic AD resisting long term disease control with local corticosteroids were included. Treatment consisted of one cycle of 5 consecutive blue light-irradiations (28.9 J/cm(2. Patients were instructed to ask for treatment upon disease exacerbation despite interval therapy with topical corticosteroids. The majority of patients noted first improvements after 2-3 cycles. The EASI score was improved by 41% and 54% after 3 and 6 months, respectively (p≤0.005, and p≤0.002. Significant improvement of pruritus, sleep and life quality was noted especially after 6 months. Also, frequency and intensity of disease exacerbations and the usage of topical corticosteroids was reduced. Finally, immunohistochemistry of skin biopsies obtained at baseline and after 5 and 15 days revealed that, unlike UV light, blue light-treatment did not induce Langerhans cell or T cell depletion from skin. CONCLUSIONS/SIGNIFICANCE: Blue light-irradiation may represent a suitable treatment option for AD providing long term control of disease. Future studies with larger patient cohorts within a randomized, placebo-controlled clinical trial are required to confirm this observation.

  20. The blue-light receptor CmWC-1 mediates fruit body development and secondary metabolism in Cordyceps militaris.

    Science.gov (United States)

    Yang, Tao; Guo, Mingmin; Yang, Huaijun; Guo, Suping; Dong, Caihong

    2016-01-01

    Light is an essential factor for pigment formation and fruit body development in Cordyceps militaris, a well-known edible and medicinal fungus. Cmwc-1, a homolog of the blue-light receptor gene white collar-1 (wc-1) in Neurospora crassa, was cloned from the C. militaris genome in our previous study. Here, Cmwc-1 gene inactivation results in thicker aerial hyphae, disordered fruit body development, a significant reduction in conidial formation, and carotenoid and cordycepin production. These characteristics were restored when the ΔCmwc-1 strains were hybridized with wild-type strains of the opposite mating type. A genome-wide expression analysis revealed that there were 1042 light-responsive genes in the wild-type strain and only 458 in the ΔCmwc-1 strain. Among five putative photoreceptors identified, Vivid, cryptochrome-1, and cyclobutane pyrimidine dimer photolyase are strongly induced by light in a Cmwc-1-dependent manner, while phytochrome and cryptochrome-2 were not induced. The transcription factors involved in the fungal light reaction were mainly of the Zn2Cys6 type. CmWC-1 regulates adenylosuccinate synthase, an important enzyme for adenosine de novo synthesis, which could explain the reduction in cordycepin production. Some G protein-coupled receptors that control fungal fruit body formation and the sexual cycle were regulated by CmWC-1, and the cAMP pathway involved in light signal transduction in N. crassa was not critical for the photoreaction in the fungus here. A transcriptional analysis indicated that steroid biosynthesis was more active in the ΔCmwc-1 strain, suggesting that CmWC-1 might switch the vegetative growth state to primordia differentiation by suppressing the expression of related genes.

  1. Chloroplasts continuously monitor photoreceptor signals during accumulation movement.

    Science.gov (United States)

    Tsuboi, Hidenori; Wada, Masamitsu

    2013-07-01

    Under low light conditions, chloroplasts gather at a cell surface to maximize light absorption for efficient photosynthesis, which is called the accumulation response. Phototropin1 (phot1) and phototropin2 (phot2) were identified as blue light photoreceptors in the accumulation response that occurs in Arabidopsis thaliana and Adiantum capillus-veneris with neochrome1 (neo1) as a red light photoreceptor in A. capillus-veneris. However, the signal molecule that is emitted from the photoreceptors and transmitted to the chloroplasts is not known. To investigate this topic, the accumulation response was induced by partial cell irradiation with a microbeam of red, blue and far-red light in A. capillus-veneris gametophyte cells. Chloroplasts moved towards the irradiated region and were able to sense the signal as long as its signal flowed. The signal from neo1 had a longer life than the signal that came from phototropins. When two microbeams with the same wavelength and the same fluence rate were placed 20 μm apart from each other and were applied to a dark-adapted cell, chloroplasts at an equidistant position always moved towards the center (midpoint) of the two microbeams, but not towards either one. This result indicates that chloroplasts are detecting the concentration of the signal but not the direction of signal flow. Chloroplasts repeatedly move and stop at roughly 10 s intervals during the accumulation response, suggesting that they monitor the intermittent signal waves from photoreceptors.

  2. In-car nocturnal blue light exposure improves motorway driving: a randomized controlled trial.

    Directory of Open Access Journals (Sweden)

    Jacques Taillard

    Full Text Available Prolonged wakefulness greatly decreases nocturnal driving performance. The development of in-car countermeasures is a future challenge to prevent sleep-related accidents. The aim of this study is to determine whether continuous exposure to monochromatic light in the short wavelengths (blue light, placed on the dashboard, improves night-time driving performance. In this randomized, double-blind, placebo-controlled, cross-over study, 48 healthy male participants (aged 20-50 years drove 400 km (250 miles on motorway during night-time. They randomly and consecutively received either continuous blue light exposure (GOLite, Philips, 468 nm during driving or 2*200 mg of caffeine or placebo of caffeine before and during the break. Treatments were separated by at least 1 week. The outcomes were number of inappropriate line crossings (ILC and mean standard deviation of the lateral position (SDLP. Eight participants (17% complained about dazzle during blue light exposure and were removed from the analysis. Results from the 40 remaining participants (mean age ± SD: 32.9±11.1 showed that countermeasures reduced the number of inappropriate line crossings (ILC (F(2,91.11 = 6.64; p<0.05. Indeed, ILC were lower with coffee (12.51 [95% CI, 5.86 to 19.66], p = 0.001 and blue light (14.58 [CI, 8.75 to 22.58], p = 0.003 than with placebo (26.42 [CI, 19.90 to 33.71]. Similar results were found for SDLP. Treatments did not modify the quality, quantity and timing of 3 subsequent nocturnal sleep episodes. Despite a lesser tolerance, a non-inferior efficacy of continuous nocturnal blue light exposure compared with caffeine suggests that this in-car countermeasure, used occasionally, could be used to fight nocturnal sleepiness at the wheel in blue light-tolerant drivers, whatever their age. More studies are needed to determine the reproducibility of data and to verify if it can be generalized to women.ClinicalTrials.gov NCT01070004.

  3. OsHAL3, a Blue Light-Responsive Protein, Interacts with the Floral Regulator Hd1 to Activate Flowering in Rice.

    Science.gov (United States)

    Su, Lei; Shan, Jun-Xiang; Gao, Ji-Ping; Lin, Hong-Xuan

    2016-02-01

    In flowering plants, photoperiodic flowering is controlled by a complicated network. Light is one of the most important environmental stimuli that control the timing of the transition from vegetative growth to reproductive development. Several photoreceptors, including PHYA, PHYB, CRY2, and FKF1 in Arabidopsis and their homologs (OsPHYA, OsPHYB, OsPHYC, and OsCRY2) in rice, have been identified to be related to flowering. Our previous study suggests that OsHAL3, a flavin mononucleotide-binding protein, may function as a blue-light sensor. Here, we report the identification of OsHAL3 as a positive regulator of flowering in rice. OsHAL3 overexpression lines exhibited an early flowering phenotype, whereas downregulation of OsHAL3 expression by RNA interference delayed flowering under an inductive photoperiod (short-day conditions). The change in flowering time was not accompanied by altered Hd1 expression but rather by reduced accumulation of Hd3a and MADS14 transcripts. OsHAL3 and Hd1 colocalized in the nucleus and physically interacted in vivo under the dark, whereas their interaction was inhibited by white or blue light. Moreover, OsHAL3 directly bound to the promoter of Hd3a, especially before dawn. We conclude that OsHAL3, a novel light-responsive protein, plays an essential role in photoperiodic control of flowering time in rice, which is probably mediated by forming a complex with Hd1. Our findings open up new perspectives on the photoperiodic flowering pathway.

  4. Direct cell fate conversion of human somatic stem cells into cone and rod photoreceptor-like cells by inhibition of microRNA-203.

    Science.gov (United States)

    Choi, Soon Won; Shin, Ji-Hee; Kim, Jae-Jun; Shin, Tae-Hoon; Seo, Yoojin; Kim, Hyung-Sik; Kang, Kyung-Sun

    2016-07-05

    Stem cell-based photoreceptor differentiation strategies have been the recent focus of therapies for retinal degenerative diseases. Previous studies utilized embryonic stem (ES) cells and neural retina differentiation cocktails, including DKK1 and Noggin. Here, we show a novel microRNA-mediated strategy of retina differentiation from somatic stem cells, which are potential allogeneic cell sources. Human amniotic epithelial stem cells (AESCs) and umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) treated with a retina differentiation cocktail induced gene expressions of retina development-relevant genes. Furthermore, microRNA-203 (miR-203) is abundantly expressed in human AESCs and human UCB-MSCs. This miR-203 is predicted to target multiple retina development-relevant genes, particularly DKK1, CRX, RORβ, NEUROD1, NRL and THRB. The inhibition of miR-203 induced a retina differentiation of AESCs and UCB-MSCs. Moreover, successive treatments of anti-miR-203 led to the expression of both mature photoreceptor (PR) markers, rhodopsin and opsin. In addition, we determined that CRX, NRL and DKK1 are direct targets of miR-203 using a luciferase assay. Thus, the work presented here suggests that somatic stem cells can potentially differentiate into neural retina cell types when treated with anti-miR-203. They may prove to be a source of both PR subtypes for future allogeneic stem cell-based therapies of non-regenerative retina diseases.

  5. Blue light emitting diodes for optical stimulation of quartz in retrospective dosimetry and dating

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Duller, G.A.T.; Murray, A.S.

    1999-01-01

    (470 nm) gives order of magnitude greater rate of stimulation in quartz than that from conventional blue-green light filtered from a halogen lamp. A practical blue LED OSL configuration is described. From comparisons of OSL decay curves produced by green and blue light sources, and by examination......Recently developed blue light emitting diodes (LEDs) for the optical stimulation of quartz for use in routine optically stimulated luminescence (OSL) dating and retrospective dosimetry have been tested. For similar power densities, it was found that the higher energy light provided by the blue LEDs...... of the dependence of the blue LED OSL on preheat temperature, it is deduced that there is no evidence that the blue LEDs stimulate deep traps in a different manner from broadband filtered light. It is concluded that blue LEDs offer a practical alternative to existing stimulation sources. They have the significant...

  6. A modern perspective on the history of semiconductor nitride blue light sources

    Science.gov (United States)

    Maruska, Herbert Paul; Rhines, Walden Clark

    2015-09-01

    In this paper we shall discuss the development of blue light-emitting (LED) and laser diodes (LD), starting early in the 20th century. Various materials systems were investigated, but in the end, the nitrides of aluminum, gallium and indium proved to be the most effective. Single crystal thin films of GaN first emerged in 1968. Blue light-emitting diodes were first reported in 1971. Devices grown in the 1970s were prepared by the halide transport method, and were never efficient enough for commercial products due to contamination. Devices created by metal-organic vapor-phase epitaxy gave far superior performance. Actual true blue LEDs based on direct band-to-band transitions, free of recombination through deep levels, were finally developed in 1994, leading to a breakthrough in LED performance, as well as nitride based laser diodes in 1996. In 2014, the scientists who achieved these critical results were awarded the Nobel Prize in Physics.

  7. Ultraviolet radiation and blue-light emissions from spotlights incorporating tungsten halogen lamps

    CERN Document Server

    MacKinlay, Alistair F; Whillock, M J

    1989-01-01

    This report summarises measurements of the ultraviolet radiation and blue-light emissions from eleven 'desk-top' tungsten halogen (quartz) lamps and one 'floor-standing' tungsten halogen (quartz) lamp available in the UK. Values of occupational hazard weighted and erythemally weighted ultraviolet radiation irradiance and measurements and relevant calculations of blue-light hazards are presented. It is concluded that the safety design of some desk-top tungsten halogen lamps is inadequate to prevent unnecessary exposure of the skin to potentially harmful ultraviolet radiation. It is recommended that all tungsten halogen lamps should have sufficient filtration to reduce their ultraviolet emissions to an acceptably low level. As long as the comfort aversion responses of the eye are respected, direct viewing of the lamps examined should not constitute a retinal hazard.

  8. Output blue light evaluation for phosphor based smart white LED wafer level packages.

    Science.gov (United States)

    Kolahdouz, Zahra; Rostamian, Ali; Kolahdouz, Mohammadreza; Ma, Teng; van Zeijl, Henk; Zhang, Kouchi

    2016-02-22

    This study presents a blue light detector for evaluating the output light of phosphor based white LED package. It is composed of a silicon stripe-shaped photodiode designed and implemented in a 2 μm BiCMOS process which can be used for wafer level integration of different passive and active devices all in just 5 lithography steps. The final device shows a high selectivity to blue light. The maximum responsivity at 480 nm is matched with the target blue LED illumination. The designed structure have better responsivity compared to simple photodiode structure due to reducing the effect of dead layer formation close to the surface because of implantation. It has also a two-fold increase in the responsivity and quantum efficiency compared to previously similar published sensors.

  9. High-efficiency blue light generation at 426 nm in low pump regime

    Science.gov (United States)

    Tian, Jianfeng; Yang, Chen; Xue, Jia; Zhang, Yuchi; Li, Gang; Zhang, Tiancai

    2016-05-01

    We report high-efficiency Ti:sapphire-laser-based frequency doubling at the cesium D2 line 852 nm using a 20 mm-long periodically-poled potassium titanyl phosphate crystal in a bow-tie four-mirror ring enhancement cavity. The relatively complete cavity design procedure is presented. Focusing that is over twice as loose as optimal focusing is used, and both the fundamental frequency wave and second harmonic beam absorption-induced thermal lensing effects are weakened. Blue light of 210 mW at 426 nm, where absorption is severe, was obtained with 310 mW mode-matched fundamental light, corresponding to conversion efficiency of up to 67%. The blue light beam power showed 1.5% RMS fluctuation over 40 min.

  10. Novel blue-light-emitting hybrid materials based on oligothiophene acids and ZnO

    Science.gov (United States)

    Jiu, Tonggang; Liu, Huibiao; Fu, Liming; He, Xiaorong; Wang, Ning; Li, Yuliang; Ai, Xicheng; Zhu, Daoben

    2004-11-01

    Novel blue-light-emitting materials based on ZnO and 2,2'-bithiophene-5,5'-dicarboxylic acid (DTDA), 4',3″-dipentyl-5,2': 5',2″: 5″,2‴-quaterthiophene-2,5‴-dicarboxylic acid (QTDA) have been prepared. The hybrid materials show that the PL λmax are at 450 and 425 nm for DTDA-ZnO and QTDA-ZnO, respectively.

  11. Gap state related blue light emitting boron-carbon core shell structures

    Science.gov (United States)

    Singh, Paviter; Kaur, Manpreet; Singh, Bikramjeet; Kaur, Gurpreet; Singh, Kulwinder; Kumar, Manjeet; Bala, Rajni; Thakur, Anup; Kumar, Akshay

    2016-05-01

    Boron- carbon core shell structures have been synthesized by solvo-thermal synthesis route. The synthesized material is highly pure. X-ray diffraction analysis confirms the reduction of reactants in to boron and carbon. Scanning Electron Microscopy (SEM) analysis showed that the shell is uniform with average thickness of 340 nm. Photo luminescence studies showed that the material is blue light emitting with CIE color coordinates: x=0.16085, y=0.07554.

  12. Impairment of extramitochondrial oxidative phosphorylation in mouse rod outer segments by blue light irradiation.

    Science.gov (United States)

    Calzia, Daniela; Panfoli, Isabella; Heinig, Nora; Schumann, Ulrike; Ader, Marius; Traverso, Carlo Enrico; Funk, Richard H W; Roehlecke, Cora

    2016-06-01

    Exposure to short wavelength light causes increased reactive oxygen intermediates production in the outer retina, particularly in the rod Outer Segments (OS). Consistently, the OS were shown to conduct aerobic ATP production through the ectopic expression of the electron transfer chain complexes I-IV and F1Fo-ATP synthase. These facts prompted us to verify if the oxidative phosphorylation in the OS is implied in the oxidative damage of the blue-light (BL) treated OS, in an organotypic model of mouse retina. Whole mouse eyeball cultures were treated with short wavelength BL (peak at 405 nm, output power 1 mW/cm(2)) for 6 h. Immunogold transmission electron microscopy confirmed the expression of Complex I and F1Fo-ATP synthase in the OS. In situ histochemical assays on unfixed sections showed impairment of respiratory Complexes I and II after BL exposure, both in the OS and IS, utilized as a control. Basal O2 consumption and ATP synthesis were impaired in the OS purified from blue-light irradiated eyeball cultures. Electron transfer capacity between Complex I and II as well as activity of Complexes I and II was decreased in blue-light irradiated purified OS. The severe malfunctioning of the OS aerobic respiratory capacity after 6 h BL treatment may be the consequence of a self-induced damage. BL exposure would cause an initial over-functioning of both the phototransduction and respiratory chain, with reactive oxygen species production. In a self-renewal vicious cycle, membrane and protein oxidative damage, proton leakage and uncoupling, would impair redox chains, perpetuating the damage and causing hypo-metabolism with eventual apoptosis of the rod. Data may shed new light on the rod-driven retinopathies such as Age Related Macular Degeneration, of which blue-light irradiated retina represents a model.

  13. Amber lenses to block blue light and improve sleep: a randomized trial.

    Science.gov (United States)

    Burkhart, Kimberly; Phelps, James R

    2009-12-01

    All light is not equal: blue wavelengths are the most potent portion of the visible electromagnetic spectrum for circadian regulation. Therefore, blocking blue light could create a form of physiologic darkness. Because the timing and quantity of light and darkness both affect sleep, evening use of amber lenses to block blue light might affect sleep quality. Mood is also affected by light and sleep; therefore, mood might be affected by blue light blockade. In this study, 20 adult volunteers were randomized to wear either blue-blocking (amber) or yellow-tinted (blocking ultraviolet only) safety glasses for 3 h prior to sleep. Participants completed sleep diaries during a one-week baseline assessment and two weeks' use of glasses. Outcome measures were subjective: change in overall sleep quality and positive/negative affect. Results demonstrated that sleep quality at study outset was poorer in the amber lens than the control group. Two- by three-way ANOVA revealed significant (p sleep over the three weeks and experimental condition. At the end of the study, the amber lens group experienced significant (p improvement in sleep quality relative to the control group and positive affect (p = .005). Mood also improved significantly relative to controls. A replication with more detailed data on the subjects' circadian baseline and objective outcome measures is warranted.

  14. Effect of LED Blue Light on Penicillium digitatum and Penicillium italicum Strains.

    Science.gov (United States)

    Lafuente, María T; Alférez, Fernando

    2015-11-01

    Studies on the antimicrobial properties of light have considerably increased due in part to the development of resistance to actual control methods. This study investigates the potential of light-emitting diodes (LED) blue light for controlling Penicillium digitatum and Penicillium italicum. These fungi are the most devastating postharvest pathogens of citrus fruit and cause important losses due to contaminations and the development of resistant strains against fungicides. The effect of different periods and quantum fluxes, delaying light application on the growth and morphology of P. digitatum strains resistant and sensitive to fungicides, and P. italicum cultured at 20°C was examined. Results showed that blue light controls the growth of all strains and that its efficacy increases with the quantum flux. Spore germination was always avoided by exposing the cultures to high quantum flux (700 μmol m(-2) s(-1) ) for 18 h. Continuous light had an important impact on the fungus morphology and a fungicidal effect when applied at a lower quantum flux (120 μmol m(-2) s(-1) ) to a growing fungus. Sensitivity to light increased with mycelium age. Results show that blue light may be a tool for P. digitatum and P. italicum infection prevention during handling of citrus fruits.

  15. Phototropin 2 is involved in blue light-induced anthocyanin accumulation in Fragaria x ananassa fruits.

    Science.gov (United States)

    Kadomura-Ishikawa, Yasuko; Miyawaki, Katsuyuki; Noji, Sumihare; Takahashi, Akira

    2013-11-01

    Anthocyanins are widespread, essential secondary metabolites in higher plants during color development in certain flowers and fruits. In strawberries, anthocyanins are also key contributors to fruit antioxidant capacity and nutritional value. However, the effects of different light qualities on anthocyanin accumulation in strawberry (Fragaria x ananassa, cv. Sachinoka) fruits remain elusive. In the present study, we showed the most efficient increase in anthocyanin content occurred by blue light irradiation. Light sensing at the molecular level was investigated by isolation of two phototropin (FaPHOT1 and FaPHOT2), two cryptochrome (FaCRY1 and FaCRY2), and two phytochrome (FaPHYA and FaPHYB) homologs. Expression analysis revealed only FaPHOT2 transcripts markedly increased depending on fruit developmental stage, and a corresponding increase in anthocyanin content was detected. FaPHOT2 knockdown resulted in decreased anthocyanin content; however, overexpression increased anthocyanin content. These findings suggested blue light induced anthocyanin accumulation, and FaPHOT2 may play a role in sensing blue light, and mediating anthocyanin biosynthesis in strawberry fruits. This is the first report to find a relationship between visible light sensing, and color development in strawberry fruits.

  16. Light emitting diode-generated blue light modulates fibrosis characteristics: fibroblast proliferation, migration speed, and reactive oxygen species generation.

    Science.gov (United States)

    Mamalis, Andrew; Garcha, Manveer; Jagdeo, Jared

    2015-02-01

    Blue light is part of the visible light spectrum that does not generate harmful DNA adducts associated with skin cancer and photoaging, and may represent a safer therapeutic modality for treatment of keloid scars and other fibrotic skin diseases. Our laboratory previously demonstrated that light-emitting diode (LED) red and infrared light inhibits proliferation of skin fibroblasts. Moreover, different wavelengths of light can produce different biological effects. Furthermore, the effects of LED blue light (LED-BL) on human skin fibroblasts are not well characterized. This study investigated the effects of LED-BL on human skin fibroblast proliferation, viability, migration speed, and reactive oxygen-species (ROS) generation. Irradiation of adult human skin fibroblasts using commercially-available LED-BL panels was performed in vitro, and modulation of proliferation and viability was quantified using the trypan blue dye exclusion assay, migratory speed was assessed using time-lapse video microscopy, and intracellular ROS generation was measured using the dihydrorhodamine flow cytometry assay. Statistical differences between groups were determined by ANOVA and Student's t-test. Human skin fibroblasts treated with LED-BL fluences of 5, 10, 15, 30, and 80 J/cm(2) demonstrated statistically significant dose-dependent decreases in relative proliferation of 8.4%, 29.1%, 33.8%, 51.7%, and 55.1%, respectively, compared to temperature and environment matched bench control plates, respectively. LED-BL fluences of 5, 30, 45, and 80 J/cm(2) decreased fibroblast migration speed to 95 ± 7.0% (P = 0.64), 81.3 ± 5.5% (P = 0.021), 48.5 ± 2.7% (P < 0.0001), and 32.3 ± 1.9% (P < 0.0001), respectively, relative to matched controls. LED fluences of 5, 10, 30, and 80 J/cm(2) resulted in statistically significant increases in reactive oxygen species of 110.4%, 116.6%, 127.5%, and 130%, respectively, relative to bench controls. At the fluences

  17. The Effect of Different Doses of Blue Light on the Biometric Traits and Photosynthesis of Dill Plants

    Directory of Open Access Journals (Sweden)

    Barbara FRĄSZCZAK

    2016-06-01

    Full Text Available The supplementation of blue light to red light enhanced plant growth compared with the use of red alone. The aim of the study was to determine the effect of different doses of blue light on the biometric traits and photosynthesis of dill plants. The plants were grown in pots in a growth chamber. They were grown in red light (100 μmol m-2 s-1 and blue light (from 10 to 50 μmol m-2 s-1 in five combinations. Light emitting diode modules were the source of light. The plants were evaluated every 7 days during vegetation, for the first time - seven days after germination and later on the 14th, 21st and 28th day after germination. The share of blue light in the spectrum significantly influenced the biometric traits of the dill plants. It significantly inhibited the elongation growth of the plants and negatively affected the increase in fresh weight. A small dose of blue light (20% had positive effect on the plants’ area. The research did not reveal a simple relationship between the amount of blue light and dry weight yield. The value of physiological indexes depended both on the combination and measurement time. The plants from the combination with 30% blue light were characterised by the greatest photosynthesis intensity. An effective share of blue light in the spectrum may range from 10 to 30% in relation to red light and depends on the plant’s development phase and on the result we want to achieve in the cultivation of plants.

  18. The Blue Light-Dependent Polyubiquitination and Degradation of Arabidopsis Cryptochrome2 Requires Multiple E3 Ubiquitin Ligases.

    Science.gov (United States)

    Liu, Qing; Wang, Qin; Liu, Bin; Wang, Wei; Wang, Xu; Park, Joon; Yang, Zhenming; Du, Xinglin; Bian, Mingdi; Lin, Chentao

    2016-10-01

    Cryptochromes are blue light receptors regulated by light-dependent ubiquitination and degradation in both plant and animal lineages. The Arabidopsis genome encodes two cryptochromes, CRY1 and CRY2, of which CRY2 undergoes blue light-dependent ubiquitination and 26S proteasome-dependent degradation. The molecular mechanism regulating blue light-dependent proteolysis of CRY2 is still not fully understood. We found that the F-box proteins ZEITLUPE (ZTL) and Lov Kelch Protein2 (LKP2), which mediate blue light suppression of degradation of the CRY2 signaling partner CIB1, are not required for the blue light-dependent CRY2 degradation. We further showed that the previously reported function of the COP1-SPA1 protein complex in blue light-dependent CRY2 degradation is more likely to be attributable to its cullin 4 (CUL4)-based E3 ubiquitin ligase activity than its activity as the cryptochrome signaling partner. However, the blue light-dependent CRY2 degradation is only partially impaired in the cul4 mutant, the cop1-5 null mutant and the spa1234 quadruple mutant, suggesting a possible involvement of additional E3 ubiquitin ligases in the regulation of CRY2. Consistent with this hypothesis, we demonstrated that the blue light-dependent CRY2 degradation is significantly impaired in the temperature-sensitive cul1 mutant allele (axr6-3), especially under the non-permissive temperature. Based on these and other results presented, we propose that photoexcited CRY2 undergoes Lys48-linked polyubiquitination catalyzed by the CUL4- and CUL1-based E3 ubiquitin ligases.

  19. Modelling the optical response of human retinal photoreceptors to plane wave illumination with the finite integration technique

    Science.gov (United States)

    Akhlagh Moayed, Alireza; Dang, Shannon; Ramahi, Omar M.; Bizheva, Kostadinka K.

    2009-02-01

    The early stages of ocular diseases such as Diabetic Retinopathy are manifested by morphological changes in retinal tissue occurring on cellular level. Therefore, a number of ophthalmic diseases can be diagnosed at an early stage by detecting spatial and temporal variations in the scattering profile of retinal tissue. It was recently demonstrated that, OCT can be used to probe the functional response of retinal photoreceptors to external light stimulation [1]-[3]. fUHROCT measures localized differential changes in the retina reflectivity over time resulting from external light stimulation of the retina. Currently the origins of the observed reflectivity changes are not well understood. However, due to the complex nature of retinal physiology using purely experimental approaches in this case is problematic. For example fUHROCT is sensitive to small changes in the refractive index of biological tissue which as demonstrated previously, can result from a number of processes such as membrane hyperpolarization, osmotic swelling, metabolic changes, etc. In this paper, we present a computational model of interaction between photoreceptor cells and optical plane wave based on the Finite Integration Technique (FIT).

  20. Blue-Light-Independent Activity of Arabidopsis Cryptochromes in the Regulation of Steady-State Levels of Protein and mRNA Expression

    Institute of Scientific and Technical Information of China (English)

    Yue-Jun Yang; Xuan-Ming Liu; Chen-Tao Lin; Ze-Cheng Zuo; Xiao-Ying Zhao; Xu Li; John Klejnot; Yan Li; Ping Chen; Song-Ping Liang; Xu-Hong Yu

    2008-01-01

    Cryptochromes are blue-light receptors that mediate blue-light inhibition of hypocotyl elongation and bluelight stimulation of floral initiation in Arabidopsis. In addition to their blue-light-dependent functions, cryptochromes are also involved in blue-light-independent regulation of the circadian clock, cotyledon unfolding, and hypocotyl inhibition.However, the molecular mechanism associated with the blue-light-independent function of cryptochromes remains unclear. We reported here a comparative proteomics study of the light regulation of protein expression. We showed that, as expected, the protein expression of many metabolic enzymes changed in response to both blue light and red light. Surprisingly, some light-regulated protein expression changes are impaired in the cry1cry2 mutant in both blue light and red light. This result suggests that, in addition to mediating blue-light-dependent regulation of protein expression, cryptochromes are also involved in the blue-light-independent regulation of gene expression. Consistent with this hypothesis,the cry1cry2 mutant exhibited reduced changes of mRNA expression in response to not only blue light, but also red light,although the cryptochrome effects on the red-light-dependent gene expression changes are generally less pronounced.These results support a hypothesis that, in addition to their blue-light-specific functions, cryptochromes also play roles in the control of gene expression mediated by the red/far-red-light receptor phytochromes.

  1. Choice of tracks, microtubules and/or actin filaments for chloroplast photo-movement is differentially controlled by phytochrome and a blue light receptor.

    Science.gov (United States)

    Sato, Y; Wada, M; Kadota, A

    2001-01-01

    Light induced chloroplast movement has been studied as a model system for photoreception and actin microfilament (MF)-based intracellular motilities in plants. Chloroplast photo-accumulation and -avoidance movement is mediated by phytochrome as well as blue light (BL) receptor in the moss Physcomitrella patens. Here we report the discovery of an involvement of a microtubule (MT)-based system in addition to an MF-based system in photorelocation of chloroplasts in this moss. In the dark, MTs provided tracks for rapid movement of chloroplasts in a longitudinal direction and MFs contributed the tracks for slow movement in any direction. We found that phytochrome responses utilized only the MT-based system, while BL responses had an alternative way of moving, either along MTs or MFs. MT-based systems were mediated by both photoreceptors, but chloroplasts showed movements with different velocity and pattern between them. No apparent difference in the behavior of chloroplast movement between the accumulation and avoidance movement was detected in phytochrome responses or BL responses, except for the direction of the movement. The results presented here demonstrate that chloroplasts use both MTs and MFs for motility and that phytochrome and a BL receptor control directional photo-movement of chloroplasts through the differential regulation of these motile systems.

  2. Flow cytometric assessment of Streptococcus mutans viability after exposure to blue light-activated curcumin.

    Science.gov (United States)

    Manoil, Daniel; Filieri, Anna; Gameiro, Cécile; Lange, Norbert; Schrenzel, Jacques; Wataha, John C; Bouillaguet, Serge

    2014-09-01

    Streptococcus mutans biofilms are considered as primary causative agents of dental caries. Photodynamic antimicrobial chemotherapy (PACT) has been recently proposed as a strategy for inactivating dental biofilms. This study aimed to investigate the effect of blue light-activated curcumin on S. mutans viability and to explore its potential as a new anti-caries therapeutic agent. The effect of different concentrations and incubation times of photo-activated curcumin on the survival of S. mutans in planktonic and biofilm models of growth was assessed by flow cytometry. Streptococcus mutans in planktonic suspensions or biofilms formed on hydroxyapatite disks were incubated for 5 or 10min with curcumin prior to blue light activation. Bacteria were labeled with SYTO 9 and propidium iodide before viability was assessed by flow cytometry. Results were statistically analyzed using one-way ANOVA and Tukey multiple comparison intervals (α=0.05). For planktonic cultures, 0.2μM of light-activated curcumin significantly reduced S. mutans viability (p<0.05). For biofilm cultures, light-activated curcumin at concentration of 40-60μM only suppressed viability by 50% (p<0.05). Independently of the mode of growth, incubation time has no significant effect on PACT efficiency. This study indicates that blue light-activated curcumin can efficiently inactivate planktonic cultures of S. mutans whereas biofilms were more resistant to treatment. Flow cytometry allowed the detection of bacteria with damaged membranes that were unable to replicate and grow after cell sorting. Further studies seem warranted to optimize the efficacy of light-activated curcumin against S. mutans biofilms. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Suppression of vagal cardiac modulation by blue light in healthy subjects.

    Science.gov (United States)

    Yuda, Emi; Ogasawara, Hiroki; Yoshida, Yutaka; Hayano, Junichiro

    2016-10-05

    In the contemporary life environments, our body is increasingly exposed to various sources of colored light, which may affect our physiological functions as non-image-forming effects. We examined the impacts of colored lights on the autonomic functions by the analysis of heart rate variability (HRV). A lighting device consisting of four organic light-emitting diode (OLED) modules (55 × 55 mm(2)) with adjustable red-green-blue color was secured 24 cm above the eyes of subject lying supine in a light-shielded laboratory. Following a 15-min supine rest, electrocardiogram and respiration were measured continuously during 3-min darkness, 6-min colored OLED illumination, and 3-min darkness under paced breathing (15 breath/min). The measurements were repeated at a 45-min interval for red, green, and blue lights with melanopsin-stimulating photon flux density (MSPFD) of 0.00, 0.10, and 0.20 μmol/m(2)/s, respectively, in 12 healthy subjects (23 ± 2 years, two females). Additionally, the effects of blue lights with 0.20, 0.10, and 0.04 μmol/m(2)/s MSPFD were examined in four healthy subjects (25-39 years, two females). HRV was analyzed for low-frequency (LF, 0.04-0.15 Hz) and high-frequency (HF, 0.20-0.30 Hz) power and LF-to-HF ratio (LF/HF). Compared to darkness before lighting, HF power decreased (P lighting on average of all color lights, whereas HF power showed a greater decrease with blue light than with red and green lights (P lighting (P light with 0.20 μmol/m(2)/s MSPFD (P light in healthy subjects most likely through melanopsin-dependent non-image-forming effect.

  4. Blue light emitting diodes for optical stimulation of quartz in retrospective dosimetry and dating

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Duller, G.A.T.; Murray, A.S.

    1999-01-01

    (470 nm) gives order of magnitude greater rate of stimulation in quartz than that from conventional blue-green light filtered from a halogen lamp. A practical blue LED OSL configuration is described. From comparisons of OSL decay curves produced by green and blue light sources, and by examination...... advantages that the life-time is indefinite, and the output can be controlled electronically; this allows the power to be readily controlled by software. Unlike a filtered light source, there are no electromechanical parts, and the switch on/off times are about 10 times faster than a shutter. Finally...

  5. Soybean stem growth under high-pressure sodium with supplemental blue lighting

    Science.gov (United States)

    Wheeler, R. M.; Mackowiak, C. L.; Sager, J. C.

    1991-01-01

    To study high-pressure sodium (HPS) lamps used for plant lighting because of their high energy conversion efficiencies, 'McCall' soybean plants were grown for 28 days in growth chambers utilizing HPS lamps, with/without supplemental light from blue phosphor fluorescent lamps. Total photosynthetic photon flux levels, including blue fluorescent, were maintained near 300 or 500 micromol/sq m s. Results indicate that employment of HPS or other blue-deficient sources for lighting at low to moderate photosynthetic photon flux levels may cause abnormal stem elongation, but this can be prevented by the addition of a small amount of supplemental blue light.

  6. Origin and Characteristics of Blue Light Emission in Solid State Cathodoluminescence of MEH-PPV

    Institute of Scientific and Technical Information of China (English)

    QU Chong; XU Zheng; TENG Feng; QIAN Lei; YU Wen-Ge; QUAN Shan-Yu; XU Xu-Rong

    2004-01-01

    Based on our previous study [Chin. Phys. Lett. 20 (2003) 1144] on the solid-state cathodoluminescence from organic luminescent materials, here we study the origin and characteristics of blue light emission in solid-state cathodoluminescence of Poly [(2-methoxy-5-(2′-ethyl-hexyloxy)phenylene vinyene] (MEH-PPV) and the dependence of each spectral peak on electric field strength. The results demonstrate that the blue spectral shift benefits from field ionization of excitons, and three regions of electric field are found, in which there are pure exciton emission, coexistence of exciton emission and radiative recombination, and pure radiative recombination.

  7. Photocatalyst-Free and Blue Light-Induced RAFT Polymerization of Vinyl Acetate at Ambient Temperature.

    Science.gov (United States)

    Ding, Chunlai; Fan, Caiwei; Jiang, Ganquan; Pan, Xiangqiang; Zhang, Zhengbiao; Zhu, Jian; Zhu, Xiulin

    2015-12-01

    Vinyl acetate is polymerized in the living way under the irradiation of blue light-emitting diodes (LEDs) or sunlight without photocatalyst at ambient temperature. 2-(Ethoxycarbonothioyl)sulfanyl propanoate is exclusively added and acts as initiator and chain transfer agent simultaneously in the current system. Poly(vinyl acetate) with well-regulated molecular weight and narrow molecular weight distribution (Đ < 1.30) is synthesized. Near quantitative end group fidelity of polymer is demonstrated by nuclear magnetic resonance (NMR) and matrix-assisteed laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).

  8. Association of flavin adenine dinucleotide with the Arabidopsis blue light receptor CRY1

    Energy Technology Data Exchange (ETDEWEB)

    Lin, C.; Robertson, D.E.; Ahmad, M. [Univ. of Pennsylvania, Philadelphia, PA (United States)] [and others

    1995-08-18

    The Arabidopsis thaliana HY4 gene encodes CRY1, a 75-kilodalton flavoprotein mediating blue light-dependent regulation of seedling development. CRY1 is demonstrated here to noncovalently bind stoichiometric amounts of flavin adenine dinucleotide (FAD). The redox properties of FAD bound by CRY1 include an unexpected stability of the neutral radical flavosemiquinone (FADH{center_dot}). The absorption properties of this flavosemiquinone provide a likely explanation for the additional sensitivity exhibited by CRY1-mediated responses in the green region of the visible spectrum. Despite the sequence homology to microbial DNA photolyases, CRY1 was found to have no detectable photolyase activity. 27 refs., 4 figs.

  9. Red Light Combined with Blue Light Irradiation Regulates Proliferation and Apoptosis in Skin Keratinocytes in Combination with Low Concentrations of Curcumin.

    Directory of Open Access Journals (Sweden)

    Tianhui Niu

    Full Text Available Curcumin is a widely known natural phytochemical from plant Curcuma longa. In recent years, curcumin has received increasing attention because of its capability to induce apoptosis and inhibit cell proliferation as well as its anti-inflammatory properties in different cancer cells. However, the therapeutic benefits of curcumin are severely hampered due to its particularly low absorption via trans-dermal or oral bioavailability. Phototherapy with visible light is gaining more and more support in dermatological therapy. Red light is part of the visible light spectrum, which is able to deeply penetrate the skin to about 6 mm, and directly affect the fibroblast of the skin dermis. Blue light is UV-free irradiation which is fit for treating chronic inflammation diseases. In this study, we show that curcumin at low concentrations (1.25-3.12 μM has a strong anti-proliferative effect on TNF-α-induced psoriasis-like inflammation when applied in combination with light-emitting-diode devices. The treatment was especially effective when LED blue light at 405 nm was combined with red light at 630 or 660 nm, which markedly amplified the anti-proliferative and apoptosis-inducing effects of curcumin. The experimental results demonstrated that this treatment reduced the viability of human skin keratinocytes, decreased cell proliferation, induced apoptosis, inhibited NF-κB activity and activated caspase-8 and caspase-9 while preserving the cell membrane integrity. Moreover, the combined treatment also down-regulated the phosphorylation level of Akt and ERK. Taken together, our results indicated that the combination of curcumin with LED blue light united red light irradiation can attain a higher efficiency of regulating proliferation and apoptosis in skin keratinocytes.

  10. Red Light Combined with Blue Light Irradiation Regulates Proliferation and Apoptosis in Skin Keratinocytes in Combination with Low Concentrations of Curcumin

    Science.gov (United States)

    Cai, Qing; Ren, Qu; Wei, Lizhao

    2015-01-01

    Curcumin is a widely known natural phytochemical from plant Curcuma longa. In recent years, curcumin has received increasing attention because of its capability to induce apoptosis and inhibit cell proliferation as well as its anti-inflammatory properties in different cancer cells. However, the therapeutic benefits of curcumin are severely hampered due to its particularly low absorption via trans-dermal or oral bioavailability. Phototherapy with visible light is gaining more and more support in dermatological therapy. Red light is part of the visible light spectrum, which is able to deeply penetrate the skin to about 6 mm, and directly affect the fibroblast of the skin dermis. Blue light is UV-free irradiation which is fit for treating chronic inflammation diseases. In this study, we show that curcumin at low concentrations (1.25–3.12 μM) has a strong anti-proliferative effect on TNF-α-induced psoriasis-like inflammation when applied in combination with light-emitting-diode devices. The treatment was especially effective when LED blue light at 405 nm was combined with red light at 630 or 660 nm, which markedly amplified the anti-proliferative and apoptosis-inducing effects of curcumin. The experimental results demonstrated that this treatment reduced the viability of human skin keratinocytes, decreased cell proliferation, induced apoptosis, inhibited NF-κB activity and activated caspase-8 and caspase-9 while preserving the cell membrane integrity. Moreover, the combined treatment also down-regulated the phosphorylation level of Akt and ERK. Taken together, our results indicated that the combination of curcumin with LED blue light united red light irradiation can attain a higher efficiency of regulating proliferation and apoptosis in skin keratinocytes. PMID:26382065

  11. Hydrogen peroxide generated by NADPH oxidase is involved in high blue-light-induced chloroplast avoidance movements in Arabidopsis

    Science.gov (United States)

    Wen, Feng; Xing, Da; Zhang, Lingrui

    2009-08-01

    One of the most important functions of blue light is to induce chloroplast movements by reducing the damage to photosynthetic machinery under excess light. Hydrogen peroxide (H2O2), generated by various environmental stimuli, can act as a signaling molecule that regulates a number of developmental processes and environmental responses. To investigate whether H2O2 is involved in high blue light-induced chloroplast avoidance movements, we use luminescence spectrometer to observe H2O2 generation with the assistance of the fluorescence probe dichlorofluorescin diacetate (H2DCF-DA). After treatment with high blue light, a large quantity of H2O2 indicated by the fluorescence intensity of DCF is produced in a dose-dependent manner in leaf strip of Arabidopsis. Enzymatic assay shows that the activity of NADPH oxidase, which is a major site for H2O2 generation, also rapidly increases in treated strips. Exogenously applied H2O2 can promote the high blue light-induced chloroplast movements. Moreover, high blue light-induced H2O2 generation can be abolished completely by addition of exogenous catalase (CAT), and partly by diphenylene iodonium (DPI) and dichlorophenyl dimethylurea (DCMU), which are an NADPH oxidase inhibitor and a blocker of electron transport chain. And subsequent chloroplast movements can be abolished by CAT and DPI, but not by DCMU. These results presented here suggested that high blue light can induce oxidative burst, and NADPH oxidase as a major producer for H2O2 is involved in blue light-induced chloroplast avoidance movements.

  12. Green-light supplementation for enhanced lettuce growth under red- and blue-light-emitting diodes

    Science.gov (United States)

    Kim, Hyeon-Hye; Goins, Gregory D.; Wheeler, Raymond M.; Sager, John C.

    2004-01-01

    Plants will be an important component of future long-term space missions. Lighting systems for growing plants will need to be lightweight, reliable, and durable, and light-emitting diodes (LEDs) have these characteristics. Previous studies demonstrated that the combination of red and blue light was an effective light source for several crops. Yet the appearance of plants under red and blue lighting is purplish gray making visual assessment of any problems difficult. The addition of green light would make the plant leave appear green and normal similar to a natural setting under white light and may also offer a psychological benefit to the crew. Green supplemental lighting could also offer benefits, since green light can better penetrate the plant canopy and potentially increase plant growth by increasing photosynthesis from the leaves in the lower canopy. In this study, four light sources were tested: 1) red and blue LEDs (RB), 2) red and blue LEDs with green fluorescent lamps (RGB), 3) green fluorescent lamps (GF), and 4) cool-white fluorescent lamps (CWF), that provided 0%, 24%, 86%, and 51% of the total PPF in the green region of the spectrum, respectively. The addition of 24% green light (500 to 600 nm) to red and blue LEDs (RGB treatment) enhanced plant growth. The RGB treatment plants produced more biomass than the plants grown under the cool-white fluorescent lamps (CWF treatment), a commonly tested light source used as a broad-spectrum control.

  13. Kinetic separation of phototropism from blue-light inhibition of stem elongation

    Science.gov (United States)

    Cosgrove, D. J.

    1985-01-01

    These experiments tested the hypothesis that phototropic bending arises when a light gradient across the stem differentially inhibits cell elongation because of direct inhibition of cell elongation by light (the Blaauw hypothesis). Continuous irradiation of dark-grown cucumber seedlings (Cucumis sativus L.) with unilateral blue light inhibited hypocotyl elongation within 30 s, but did not induce phototropic curvature until 4.5 h after the start of irradiation. Marking experiments showed that curvature began simultaneously at the top and bottom of the growing region. In situ measurements of the light gradient across the stem with a glass fiber optic indicated that a 5- to 6-fold difference in fluence rate was established on the two sides of the stem. The light gradient established at the start of irradiation was the same as that after 6 h of irradiation. Changes in gravitropic responsiveness during this period were also ruled out. Calculations show that the light gradient should have caused curvature which would be detectable within 30 to 60 min and which would extrapolate to the start of irradiation--if the Blaauw hypothesis were correct. The long lag for phototropism in this case indicates that rapid inhibition of cell elongation by blue light does not cause the asymmetrical growth of phototropism. Rather, phototropism is superimposed upon this separate light growth response.

  14. Cross Talk between a Fungal Blue-Light Perception System and the Cyclic AMP Signaling Pathway

    Science.gov (United States)

    Casas-Flores, Sergio; Rios-Momberg, Mauricio; Rosales-Saavedra, Teresa; Martínez-Hernández, Pedro; Olmedo-Monfil, Vianey; Herrera-Estrella, Alfredo

    2006-01-01

    Blue light regulates many physiological and developmental processes in fungi. In Trichoderma atroviride the complex formed by the BLR-1 and BLR-2 proteins appears to play an essential role as a sensor and transcriptional regulator in photoconidiation. Here we demonstrate that the BLR proteins are necessary for carbon deprivation induced conidiation, even in the absence of light, pointing to the existence of an unprecedented cross talk between light and carbon sensing. Further, in contrast to what has been found in all other fungal systems, clear BLR-independent blue-light responses, including the activation of protein kinase A (PKA) and the regulation of gene expression, were found. Expression of an antisense version of the pkr-1 gene, encoding the regulatory subunit of PKA, resulted in a nonsporulating phenotype, whereas overexpression of the gene produced colonies that conidiate even in the dark. In addition, overexpression of pkr-1 blocked the induction of early light response genes. Thus, our data demonstrate that PKA plays an important role in the regulation of light responses in Trichoderma. Together, these observations suggest that the BLR complex plays a general role in sensing environmental cues that trigger conidiation and that such a role can be separated from its function as a transcription factor. PMID:16524905

  15. Repeatability and reproducibility of individual abutment impression, assessed with a blue light scanner

    Science.gov (United States)

    Kim, Dong-Yeon; Lee, Jae-Jun; Kim, Ji-Hwan

    2016-01-01

    PURPOSE We assessed the repeatability and reproducibility of abutment teeth dental impressions, digitized with a blue light scanner, by comparing the discrepancies in repeatability and reproducibility values for different types of abutment teeth. MATERIALS AND METHODS To evaluate repeatability, impressions of the canine, first premolar, and first molar, prepared for ceramic crowns, were repeatedly scanned to acquire 5 sets of 3-dimensional data via stereolithography (STL) files. Point clouds were compared and the error sizes were measured (n=10, per type). To evaluate reproducibility, the impressions were rotated by 10-20° on the table and scanned. These data were compared to the first STL data and the error sizes were measured (n=5, per type). One-way analysis of variance was used to assess the repeatability and reproducibility of the 3 types of teeth, and Tukey honest significant differences (HSD) multiple comparison test was used for post hoc comparisons (α=.05). RESULTS The differences with regard to repeatability were 4.5, 2.7, and 3.1 µm for the canine, premolar, and molar, indicating the poorest repeatability for the canine (P<.001). For reproducibility, the differences were 6.6, 5.8, and 11.0 µm indicating the poorest reproducibility for the molar (P=.007). CONCLUSION Our results indicated that impressions of individual abutment teeth, digitized with a blue light scanner, had good repeatability and reproducibility. PMID:27350856

  16. Transcriptome Analysis Reveals that Red and Blue Light Regulate Growth and Phytohormone Metabolism in Norway Spruce [Picea abies (L. Karst].

    Directory of Open Access Journals (Sweden)

    Fangqun OuYang

    Full Text Available The mechanisms by which different light spectra regulate plant shoot elongation vary, and phytohormones respond differently to such spectrum-associated regulatory effects. Light supplementation can effectively control seedling growth in Norway spruce. However, knowledge of the effective spectrum for promoting growth and phytohormone metabolism in this species is lacking. In this study, 3-year-old Norway spruce clones were illuminated for 12 h after sunset under blue or red light-emitting diode (LED light for 90 d, and stem increments and other growth traits were determined. Endogenous hormone levels and transcriptome differences in the current needles were assessed to identify genes related to the red and blue light regulatory responses. The results showed that the stem increment and gibberellin (GA levels of the seedlings illuminated by red light were 8.6% and 29.0% higher, respectively, than those of the seedlings illuminated by blue light. The indoleacetic acid (IAA level of the seedlings illuminated by red light was 54.6% lower than that of the seedlings illuminated by blue light, and there were no significant differences in abscisic acid (ABA or zeatin riboside [ZR] between the two groups of seedlings. The transcriptome results revealed 58,736,166 and 60,555,192 clean reads for the blue-light- and red-light-illuminated samples, respectively. Illumina sequencing revealed 21,923 unigenes, and 2744 (approximately 93.8% out of 2926 differentially expressed genes (DEGs were found to be upregulated under blue light. The main KEGG classifications of the DEGs were metabolic pathway (29%, biosynthesis of secondary metabolites (20.49% and hormone signal transduction (8.39%. With regard to hormone signal transduction, AUXIN-RESISTANT1 (AUX1, AUX/IAA genes, auxin-inducible genes, and early auxin-responsive genes [(auxin response factor (ARF and small auxin-up RNA (SAUR] were all upregulated under blue light compared with red light, which might have

  17. Direct involvement of hydrogen peroxide in curvature of wheat coleoptile in blue-light-treated and dark-grown coleoptiles.

    Science.gov (United States)

    Chandrakuntal, Kumar; Kumar, Pradeep G; Laloraya, Malini; Laloraya, Manmohan M

    2004-07-09

    Blue-light-induced photomorphogenesis is the sum total of a sequence of phenomena involving absorption of light by specific receptors, generation of a signal, processing transmembrane transport of signal, and the activation of a cascade of reactions in the cell interior. Though four blue-light receptors cryptochrome1, cryptochrome2, phototropin1, and phototropin2 have been identified, the signal transduction events associated with blue-light receptor activation are not understood. In this report, we demonstrate the generation and spatiotemporal distribution of H(2)O(2) in wheat coleoptile in response to blue light. Interception of the free-radical generation pathways dithiothreitol and propyl gallate rendered wheat coleoptile tips phototropically non-responsive. Unilateral application of H(2)O(2) onto the sub-apical region of a growing coleoptile brought about curvature in dark. Blue light also caused lipid peroxidation and augmented membrane rigidity of coleoptile cell membranes. We conclude that H(2)O(2) can act as a translocating second messenger that could bring about coleoptile curvature, and the signaling events may trigger Ca(2+) signaling cascades, changes in gene expression, and protein modifications.

  18. Blue light hazard optimization for white light-emitting diode sources with high luminous efficacy of radiation and high color rendering index

    Science.gov (United States)

    Zhang, Jingjing; Guo, Weihong; Xie, Bin; Yu, Xingjian; Luo, Xiaobing; Zhang, Tao; Yu, Zhihua; Wang, Hong; Jin, Xing

    2017-09-01

    Blue light hazard of white light-emitting diodes (LED) is a hidden risk for human's photobiological safety. Recent spectral optimization methods focus on maximizing luminous efficacy and improving color performances of LEDs, but few of them take blue hazard into account. Therefore, for healthy lighting, it's urgent to propose a spectral optimization method for white LED source to exhibit low blue light hazard, high luminous efficacy of radiation (LER) and high color performances. In this study, a genetic algorithm with penalty functions was proposed for realizing white spectra with low blue hazard, maximal LER and high color rendering index (CRI) values. By simulations, white spectra from LEDs with low blue hazard, high LER (≥297 lm/W) and high CRI (≥90) were achieved at different correlated color temperatures (CCTs) from 2013 K to 7845 K. Thus, the spectral optimization method can be used for guiding the fabrication of LED sources in line with photobiological safety. It is also found that the maximum permissible exposure duration of the optimized spectra increases by 14.9% than that of bichromatic phosphor-converted LEDs with equal CCT.

  19. Non-invasive plant growth measurements for detection of blue-light dose response of stem elongation in Chrysanthemum morifolium

    DEFF Research Database (Denmark)

    Kjær, Katrine Heinsvig

    2012-01-01

    . In the present study a non-invasive plant growth sensor (PlantEye, Phenospex B.V, Heerlen, NL) was tested in analysing changes in diurnal stem elongation patterns and plant height in response to the spectral quality of the light environment. Plants were grown in four different LED supplemental lighting...... treatments with 0%, 12.5%, 18.5% and 22.5% blue light under greenhouse conditions in winter (18 h day/4 h night). The non-invasive measurements were carried out automatically every four hour with three repetitions, and supported by manual measurements of plant height every third day. A strong linear relation...... between the non-invasive measurements and manual measurements of plant height was achieved, and a blue-light dose-response showing a decrease in plant height in relation to an increase in blue light was demonstrated. However, the non-invasive plant growth sensor was not able to distinguish between diurnal...

  20. Photocatalytic activity of tungsten-doped TiO2 with hydrothermal treatment under blue light irradiation.

    Science.gov (United States)

    Putta, Thapanan; Lu, Ming-Chun; Anotai, Jin

    2011-09-01

    Tungsten doping and hydrothermal treatment were found to significantly improve the visible-light photoactivity of TiO(2) synthesized by the sol-gel method. It was observed that TiO(2) doped with a 0.5% W:Ti mole ratio and treated with 4 h of hydrothermal curing showed photoactivity under blue light irradiation equal to 74% of the commercial Degussa P-25 under UV irradiation, i.e., 0.01 mM 2-chlorophenol was completely removed in 120 and 90 min, respectively. Light absorptivity and photocatalytic activity under blue light irradiation were not dependent on the crystallite structure of the TiO(2). The oxidation kinetics under blue light irradiation can be effectively explained by the Langmuir-Hinshelwood model with an apparent reaction rate constant and a Langmuir constant of 3.60 × 10(-4) mM min(-1) and 206.53 mM(-1), respectively.

  1. Therapeutic effect of turquoise versus blue light with equal irradiance in preterm infants with jaundice

    DEFF Research Database (Denmark)

    Ebbesen, Finn; Madsen, Poul; Støvring, Søren

    2007-01-01

    (OSRAM L18W/860 fluorescent lamps) or blue light (Philips TL20W/52 fluorescent lamps). The concentrations of serum total bilirubin and bilirubin isomers were measured by the Vitros routine method and by HPLC, respectively. RESULTS: The decrease in serum concentrations of total bilirubin, total bilirubin...... irradiance, expressed both by serum total bilirubin, total bilirubin isomers and Z,Z-bilirubin, i.e. the turquoise spectral range is more efficient than the blue. This is in accordance with deeper penetration into the skin, lower production of the Z,E-bilirubin and greater production of E......AIM: To compare the efficiency of turquoise light with that of TL52 blue in treatment of preterm infants with jaundice at the same level of body irradiance. METHODS: Infants with gestational age 28-37 weeks and non-haemolytic hyperbilirubinemia were treated for 24 h with either turquoise light...

  2. Substituent effect to prevent autoxidation and improve spectral stability in blue light-emitting polyfluorenes.

    Science.gov (United States)

    Li, Jiu Yan; Ziegler, Andreas; Wegner, Gerhard

    2005-07-18

    A group of fluorene-based polymers, PF-1SOR and PF-2SOR, were synthesized and characterized as blue light-emitting materials. PF-1SOR and PF-2SOR displayed nematic liquid crystalline mesophase in films cast from solution. Compared with conventional polyfluorene, PF-1SOR and PF-2SOR display blue-shifted UV absorption and structureless blue fluorescence. The photoluminescence spectra of PF-1SOR and PF-2SOR were found insensitive against thermal treatment in air up to 200 degrees C and the blue electroluminescence in their light-emitting devices was independent of the driving voltage. Compared to the conventional polyfluorenes, the improved spectral stability of these polymers is attributed to the anti-oxidization effect of (3,5-di(tert-butyl)phenoxy)sulfonyl side groups attached to the backbone.

  3. High-Power Blue Light Generation by External Frequency Doubling of an Optical Parametric Oscillator

    Institute of Scientific and Technical Information of China (English)

    毕勇; 张鸿博; 孙志培; 包照日格图; 李惠清; 孔宇鹏; 林学春; 王桂玲; 张杰; 侯玮; 李瑞宁; 崔大复; 许祖彦; 宋立维; 章萍; 崔建峰; 樊仲维

    2003-01-01

    We report on an all-solid-state high-power quasi-continuous blue light source by the frequency doubling of a signal wave from an optical parametric oscillator(OPO).A 50-mm-long LiB3O5(LBO)crystal is used for the OPO,which is pumped by a diode-pumped Nd:YAG green laser(10kHz,50ns).Tunable blue emission in a new nonlinear crystal BiB3O6(BiBO)is obtained with a wavelength range from 450 to 495 nm.The average power of the signal output is as high as 9.3 W from 924 to 970nm.The maximum output of the blue laser with the second harmonic walk-off compensation is 1.3 W average power at 470nm for 6.2 W of OPO signal light at 940nm.

  4. A New Distyrylarylene Derivative Used as Blue Light Emitter in Organic Electroluminescent Device

    Institute of Scientific and Technical Information of China (English)

    郑新友; 朱文清; 等

    2002-01-01

    A new blue electroluminescent material,distyrylarylene(DSA)derivative,4,4'-bis[2,2-(1-naphthyl,phenyl)vinyl]-1,1-biphenyl(NPVBi)is designed and synthesized.The DSA derivative shows better thermal stability because of its high glass transition temperature.A blue organic light emitting diode(OLED0with the structure ITO/TPD/NPVBi/Alq/LiF/Al is studied.The electroluminescent(EL0spectrum of the OLED exhibits that light emission originates from NPVBi with a peak at 460nm,its Commission Internationale de l'Eclairage(CIE)color coordinates are x=0.16,y=0.15,and showing independence of CIE color coordinates on current density.The new DSA derivative is expectable as a new candidate for blue light emitter in OLEDs.

  5. Evidence for the Role of Blue Light in the Development of Uveal Melanoma

    Directory of Open Access Journals (Sweden)

    Patrick Logan

    2015-01-01

    Full Text Available Uveal melanoma is the most common malignancy of the adult eye. Although it is a relatively infrequent tumor, clinical prognosis is often poor owing to a high incidence of aggressive metastatic disease, for which there are limited treatment options. Little is known about the etiology of this condition, although several risk factors have been identified. Unlike cutaneous melanoma, however, ultraviolet radiation does not figure prominently among these risk factors. In this review, we focus on an associated form of visible electromagnetic radiation, high-energy short-wave (blue light, a causative agent in various forms of age-related retina damage, as a previously overlooked risk factor in uveal melanoma development and progression. Finally, we discuss the impact of these data on contemporary ocular therapy, particularly the debate surrounding the filtering capabilities of intraocular lenses used to replace dysfunctional crystalline lenses during cataract surgery.

  6. Red and Blue Light Generation in an LiTaO3 Crystal with a Double Grating Domain Structure

    Institute of Scientific and Technical Information of China (English)

    LIU Zhao-Wei; ZHU Shi-Ning; ZHU Yong-Yuan; WANG Hui-Tian; LUO Guo-Zhen; LIU Hui; MIN Nai-Ben; LIANG Xiao-Yan; XU Zu-Yan

    2001-01-01

    Simultaneous red and blue light generation in an LiTaOs crystal with a double grating structure is reported for the first time. The double grating consists of two separate domain reversal sequences (superlattices) in seriesand is fabricated by the field poling technique at room temperature. Using a picosecond 532 nm laser as a pump source, the red light at 631 nm and blue light at 460nm are generated at the same time. A possible applicationof the superlattice crystal is presented. X

  7. Highly-Efficient Blue-Light Generation by Intracavity Frequency Doubling with LiB3O5

    Institute of Scientific and Technical Information of China (English)

    林学春; 李瑞宁; 崔大复; 姚爱云; 冯衍; 毕勇; 许祖彦

    2002-01-01

    We have investigated the generation of highly-efficient blue light in critically type-I phase-matched LiBsO5(LBO) with intracavity frequency doubling of diode-pumped Nd: YA G laser. A maximum output power of 502 m W at 473nm blue light was obtained and the overall optical-to-optical efficiency is up to 11.2%. To the best of our knowledge, this is the highest conversion efficiency for 473 nm output using a diode pumped Nd:YAG laser through LBO.

  8. Photoactivation mechanisms of flavin-binding photoreceptors revealed through ultrafast spectroscopy and global analysis methods.

    Science.gov (United States)

    Mathes, Tilo; van Stokkum, Ivo H M; Kennis, John T M

    2014-01-01

    Flavin-binding photoreceptor proteins use the isoalloxazine moiety of flavin cofactors to absorb light in the blue/UV-A wavelength region and subsequently translate it into biological information. The underlying photochemical reactions and protein structural dynamics are delicately tuned by the protein environment and represent fundamental reactions in biology and chemistry. Due to their photo-switchable nature, these proteins can be studied efficiently with laser-flash induced transient absorption and emission spectroscopy with temporal precision down to the femtosecond time domain. Here, we describe the application of both visible and mid-IR ultrafast transient absorption and time-resolved fluorescence methods in combination with sophisticated global analysis procedures to elucidate the photochemistry and signal transduction of BLUF (Blue light receptors using FAD) and LOV (Light oxygen voltage) photoreceptor domains.

  9. LED蓝光泄露安全性研究%Study on the Safety of Blue Light Leak of LED

    Institute of Scientific and Technical Information of China (English)

    申崇渝; 徐征; 赵谡玲; 黄清雨

    2014-01-01

    研究了L ED照明器件的蓝光特性。针对我国的L ED照明现状,通过测试L ED照明器件的光谱成分,根据现行国内外标准GB/T 20145-2006/CIE S009/E:2002和IEC62471:2006,以及CTL-0744_2009-laser决议,分析了L ED光生物安全性,给L ED照明灯具制造和相关安全性标准、法律制定提供参考。L ED中蓝光的辐亮度值低于100W·m -2·Sr-1时对人眼属于无危害类型,正常使用情况下不会对人眼造成伤害,但是应该注意对特殊人群(小孩)的保护,避免长时间直视光源。灯具富蓝化也会影响人的作息规律,因此色温4000 K以下,显色指数80的L ED灯具适合在室内使用,同时还要根据不同的使用距离选择不同的参数的灯具。%In this paper ,the blue light properties of LED illumination devices have been investigated .Against the status quo of China’s LED lighting ,we measured the spectrum component of LED lamps and analyzed the photobiological safety under the current domestic and international standards GB/T 20145-2006/CIE S009/E:2002 and IEC62471 :2006 standards as well as CTL-0744_2009-laser resolution ,which provides the reference to the manufacture of LED lighting lamps as well as related safety standards and laws .If the radiance intensity of blue light in LED is lower than 100 W · m -2 · Sr-1 ,there is no harm to human eyes .LEDs will not cause harm to human eyes under normal use ,but we should pay attention to the protection of special popula-tions (children) ,and make sure that they avoid looking at a light source for a long time .The research has found that the blue-rich lamps can affect the human rule of work and rest ,and therefore ,the LED lamps with color temperature below 4 000 K and color rendering index of 80 are suitable for indoor use .At the same time ,the lamps with different parameters should be selected according to the different distances .

  10. Photochemical Reactions of the LOV and LOV-Linker Domains of the Blue Light Sensor Protein YtvA

    NARCIS (Netherlands)

    Choi, S.; Nakasone, Y.; Hellingwerf, K.J.; Terazima, M.

    2016-01-01

    YtvA is a blue light sensor protein composed of an N-terminal LOV (light-oxygen-voltage) domain, a linker helix, and the C-terminal sulfate transporter and anti-sigma factor antagonist domain. YtvA is believed to act as a positive regulator for light and salt stress responses by regulating the

  11. The avoidance and aggregative movements of mesophyll chloroplasts in C(4) monocots in response to blue light and abscisic acid.

    Science.gov (United States)

    Maai, Eri; Shimada, Shouu; Yamada, Masahiro; Sugiyama, Tatsuo; Miyake, Hiroshi; Taniguchi, Mitsutaka

    2011-05-01

    In C(4) plants, mesophyll (M) chloroplasts are randomly distributed along the cell walls, whereas bundle sheath chloroplasts are located in either a centripetal or centrifugal position. It was reported previously that only M chloroplasts aggregatively redistribute to the bundle sheath side in response to extremely strong light or environmental stresses. The aggregative movement of M chloroplasts is also induced in a light-dependent fashion upon incubation with abscisic acid (ABA). The involvement of reactive oxygen species (ROS) and red/blue light in the aggregative movement of M chloroplasts are examined here in two distinct subtypes of C(4) plants, finger millet and maize. Exogenously applied hydrogen peroxide or ROS scavengers could not change the response patterns of M chloroplast movement to light and ABA. Blue light irradiation essentially induced the rearrangement of M chloroplasts along the sides of anticlinal walls, parallel to the direction of the incident light, which is analogous to the avoidance movement of C(3) chloroplasts. In the presence of ABA, most of the M chloroplasts showed the aggregative movement in response to blue light but not red light. Together these results suggest that ROS are not involved in signal transduction for the aggregative movement, and ABA can shift the blue light-induced avoidance movement of C(4)-M chloroplasts to the aggregative movement.

  12. Blue Light Emitting Diodes based on a partially conjugated Si-containing PPV-copolymer in a multilayer configuration

    NARCIS (Netherlands)

    Garten, F; Hilberer, A; Cacialli, F.; Esselink, F.J; van Dam, Y.; Schlatmann, A.R.; Friend, R.H.; Klapwijk, T.M; Hadziioannou, G

    1997-01-01

    Efficient blue Light Emitting Diodes (LEDs) based on a novel partially conjugated co-polymer (SiPPV) have been realized by a combination of techniques known to enhance the quantum efficiency of organic devices. The copolymer is homogeneously blended in a PVK-matrix to reduce the number of non-radiat

  13. Repeated exposures to blue light-activated eosin Y enhance inactivation of E. faecalis biofilms, in vitro.

    Science.gov (United States)

    Marinic, Karlo; Manoil, Daniel; Filieri, Anna; Wataha, John C; Schrenzel, Jacques; Lange, Norbert; Bouillaguet, Serge

    2015-09-01

    In dentistry, antibacterial photodynamic therapy (a-PDT) has shown promising results for inactivating bacterial biofilms causing carious, endodontic and periodontal diseases. In the current study, we assessed the ability of eosin Y exposed to 3 irradiation protocols at inactivating Enterococcus faecalis biofilms, in vitro. E. faecalis biofilms formed on hydroxyapatite disks were incubated with eosin Y (10-80μM), then activated with blue light using different irradiation protocols. Biofilms exposed to continuous exposure were incubated for 40min before being light-activated for 960 s. For the intermittent exposure, biofilms were exposed 4 times to the light/photosensitizer combination (960 s total) without renewing the photosensitizer. For repeated a-PDT, the same light dose was delivered in a series of 4 irradiation periods separated by dark periods; fresh photosensitizer was added between each light irradiation. After treatment, bacteria were immediately labeled with LIVE/DEAD BacLight Bacterial Viability kit and viability was assessed by flow cytometry (FCM). Results were statistically analyzed using one-way ANOVA and Tukey multiple comparison intervals (α=0.05). The viability of E. faecalis biofilms exposed to 10μM eosin Y, was significantly reduced compared to controls (light only-eosin Y only). After a second exposure to blue light-activated eosin Y, viability significantly decreased from 58% to 12% whereas 6.5% of the bacterial biofilm remained live after a third exposure (p<0.05). Only 3.5% of the bacterial population survived after the fourth exposure. The results of this study indicate that blue light-activated eosin Y can photoinactivate E. faecalis biofilms grown on hydroxyapatite disks. Also, repeated exposures to blue light-activated eosin Y were shown to significantly improve efficacy. Further studies seem warranted to optimize the antibacterial activity of blue light-activated eosin Y on major oral pathogens. Copyright © 2015 Elsevier B.V. All

  14. Pulsing blue light through closed eyelids: effects on acute melatonin suppression and phase shifting of dim light melatonin onset

    Directory of Open Access Journals (Sweden)

    Figueiro MG

    2014-12-01

    Full Text Available Mariana G Figueiro, Barbara Plitnick, Mark S Rea Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USA Abstract: Circadian rhythm disturbances parallel the increased prevalence of sleep disorders in older adults. Light therapies that specifically target regulation of the circadian system in principle could be used to treat sleep disorders in this population. Current recommendations for light treatment require the patients to sit in front of a bright light box for at least 1 hour daily, perhaps limiting their willingness to comply. Light applied through closed eyelids during sleep might not only be efficacious for changing circadian phase but also lead to better compliance because patients would receive light treatment while sleeping. Reported here are the results of two studies investigating the impact of a train of 480 nm (blue light pulses presented to the retina through closed eyelids on melatonin suppression (laboratory study and on delaying circadian phase (field study. Both studies employed a sleep mask that provided narrowband blue light pulses of 2-second duration every 30 seconds from arrays of light-emitting diodes. The results of the laboratory study demonstrated that the blue light pulses significantly suppressed melatonin by an amount similar to that previously shown in the same protocol at half the frequency (ie, one 2-second pulse every minute for 1 hour. The results of the field study demonstrated that blue light pulses given early in the sleep episode significantly delayed circadian phase in older adults; these results are the first to demonstrate the efficacy and practicality of light treatment by a sleep mask aimed at adjusting circadian phase in a home setting. Keywords: circadian phase, dim light melatonin onset, light through closed eyelids, blue light, sleep

  15. Psychophysical Measurements of Luminance Contrast Sensitivity and Color Discrimination with Transparent and Blue-Light Filter Intraocular Lenses.

    Science.gov (United States)

    da Costa, Marcelo Fernandes; Júnior, Augusto Paranhos; Lottenberg, Claudio Luiz; Castro, Leonardo Cunha; Ventura, Dora Fix

    2017-08-09

    The purpose of this study was to measure luminance contrast sensitivity and color vision thresholdfs in normal subjects using a blue light filter lens and transparent intraocular lens material. Monocular luminance grating contrast sensitivity was measured with Psycho for Windows (version 2.36; Cambridge Research Systems) at 3.0, 6.0, 12.0, 20.0, and 30.0 cycles per degree of visual angle (cpd) in 15 normal subjects (eight female), with a mean age of 21.6 years (SD = 3.8 years). Chromatic discrimination was assessed with the Cambridge colour test (CCT) along the protan, deutan, and tritan color confusion axes. Both tests were performed in a darkened room under two situations: with a transparent lens and with blue light filter lens. Subjective impressions were taken by subjects regarding their visual experience under both conditions. No difference was found between the luminance contrast sensitivity measured with transparent and blue light filter. However, 13/15 (87%) of the subjects reported more comfortable vision with the blue filter. In the color vision test, tritan thresholds were significantly higher for the blue filter compared with the transparent filter (p = 0.003). For protan and deutan thresholds no differences were found. Blue-yellow color vision is impaired with the blue light filter, and no impairment occurs with the transparent filter. No significant differences in thresholds were found in the luminance contrast sensitivity comparing the blue light and transparent filters. The impact of short wavelength light filtering on intrinsically photosensitive retinal ganglion cells is also discussed.

  16. Blue-light dependent inhibition of twitching motility in Acinetobacter baylyi ADP1: Additive involvement of three BLUF domain-containing proteins

    NARCIS (Netherlands)

    Bitrian, M.; Gonzalez, R.H.; Paris, G.; Hellingwerf, K.J.; Nudel, C.B.

    2013-01-01

    Twitching motility in Acinetobacter baylyi ADP1 is inhibited by moderate intensities of blue light in a temperature-dependent manner (maximally at 20 degrees C. We analyzed the involvement of four predicted blue-light-sensing-using flavin (BLUF) domain-containing proteins encoded in the genome of th

  17. Effects of continuous white light and 12h white-12h blue light-cycles on the expression of clock genes in diencephalon, liver, and skeletal muscle in chicks.

    Science.gov (United States)

    Honda, Kazuhisa; Kondo, Makoto; Hiramoto, Daichi; Saneyasu, Takaoki; Kamisoyama, Hiroshi

    2017-05-01

    The core circadian clock mechanism relies on a feedback loop comprised of clock genes, such as the brain and muscle Arnt-like 1 (Bmal1), chriptochrome 1 (Cry1), and period 3 (Per3). Exposure to the light-dark cycle synchronizes the master circadian clock in the brain, and which then synchronizes circadian clocks in peripheral tissues. Birds have long been used as a model for the investigation of circadian rhythm in human neurobiology. In the present study, we examined the effects of continuous light and the combination of white and blue light on the expression of clock genes (Bmal1, Cry1, and Per3) in the central and peripheral tissues in chicks. Seventy two day-old male chicks were weighed, allocated to three groups and maintained under three light schedules: 12h white light-12h dark-cycles group (control); 24h white light group (WW group); 12h white light-12h blue light-cycles group (WB group). The mRNA levels of clock genes in the diencephalon were significantly different between the control and WW groups. On the other hand, the alteration in the mRNA levels of clock genes was similar between the control and WB groups. Similar phenomena were observed in the liver and skeletal muscle (biceps femoris). These results suggest that 12h white-12h blue light-cycles did not disrupt the circadian rhythm of clock gene expression in chicks. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Stomatal Blue Light Response Is Present in Early Vascular Plants1[OPEN

    Science.gov (United States)

    Doi, Michio; Kitagawa, Yuki; Shimazaki, Ken-ichiro

    2015-01-01

    Light is a major environmental factor required for stomatal opening. Blue light (BL) induces stomatal opening in higher plants as a signal under the photosynthetic active radiation. The stomatal BL response is not present in the fern species of Polypodiopsida. The acquisition of a stomatal BL response might provide competitive advantages in both the uptake of CO2 and prevention of water loss with the ability to rapidly open and close stomata. We surveyed the stomatal opening in response to strong red light (RL) and weak BL under the RL with gas exchange technique in a diverse selection of plant species from euphyllophytes, including spermatophytes and monilophytes, to lycophytes. We showed the presence of RL-induced stomatal opening in most of these species and found that the BL responses operated in all euphyllophytes except Polypodiopsida. We also confirmed that the stomatal opening in lycophytes, the early vascular plants, is driven by plasma membrane proton-translocating adenosine triphosphatase and K+ accumulation in guard cells, which is the same mechanism operating in stomata of angiosperms. These results suggest that the early vascular plants respond to both RL and BL and actively regulate stomatal aperture. We also found three plant species that absolutely require BL for both stomatal opening and photosynthetic CO2 fixation, including a gymnosperm, C. revoluta, and the ferns Equisetum hyemale and Psilotum nudum. PMID:26307440

  19. Violet and blue light-induced green fluorescence emissions from dental caries.

    Science.gov (United States)

    Shakibaie, F; Walsh, L J

    2016-12-01

    The objective of this laboratory study was to compare violet and visible blue LED light-elicited green fluorescence emissions from enamel and dentine in healthy or carious states. Microscopic digital photography was undertaken using violet and blue LED illumination (405 nm and 455 nm wavelengths) of tooth surfaces, which were photographed through a custom-made stack of green compensating filters which removed the excitation light and allowed green fluorescence emissions to pass. Green channel pixel data were analysed. Dry sound enamel and sound root surfaces showed strong green fluorescence when excited by violet or blue lights. Regions of cavitated dental caries gave lower green fluorescence, and this was similar whether the dentine in the lesions was the same colour as normal dentine or was darkly coloured. The presence of saliva on the surface did not significantly change the green fluorescence, while the presence of blood diluted in saliva depressed green fluorescence. Using violet or blue illumination in combination with green compensating filters could potentially aid in the assessment of areas of mineral loss. © 2016 Australian Dental Association.

  20. Mechanism of blue-light-induced plasma-membrane depolarization in etiolated cucumber hypocotyls

    Science.gov (United States)

    Spalding, E. P.; Cosgrove, D. J.

    1992-01-01

    A large, transient depolarization of the plasma membrane precedes the rapid blue-light (BL)-induced growth suppression in etiolated seedlings of Cucumis sativus L. The mechanism of this voltage transient was investigated by applying inhibitors of ion channels and the plasma-membrane H(+)-ATPase, by manipulating extracellular ion concentrations, and by measuring cell input resistance and ATP levels. The depolarizing phase was not affected by Ca(2+)-channel blockers (verapamil, La3+) or by reducing extracellular free Ca2+ by treatment with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). However, these treatments did reduce the rate of repolarization, indicating an inward movement of Ca2+ is involved. No effects of the K(+)-channel blocker tetraethylammonium (TEA+) were detected. Vanadate and KCN, used to inhibit the H(+)-ATPase, reduced or completely inhibited the BL-induced depolarization. Levels of ATP increased by 11-26% after 1-2 min of BL. Input resistance of trichrome cells, measured with double-barreled microelectrodes, remained constant during the onset of the depolarization but decreased as the membrane voltage became more positive than -90 mV. The results indicate that the depolarization mechanism initially involves inactivation of the H(+)-ATPase with subsequent transient activation of one or more types of ion channels.

  1. Large plasma-membrane depolarization precedes rapid blue-light-induced growth inhibition in cucumber

    Science.gov (United States)

    Spalding, E. P.; Cosgrove, D. J.

    1989-01-01

    Blue-light (BL)-induced suppression of elongation of etiolated Cucumis sativus L. hypocotyls began after a 30-s lag time, which was halved by increasing the fluence rate from 10 to 100 micromoles m-2 s-1. Prior to the growth suppression, the plasma-membrane of the irradiated cells depolarized by as much as 100 mV, then returned within 2-3 min to near its initial value. The potential difference measured with surface electrodes changed with an identical time course but opposite polarity. The lag time for the change in surface potential showed an inverse dependence on fluence rate, similar to the lag for the growth inhibition. Green light and red light caused neither the electrical response nor the rapid inhibition of growth. The depolarization by BL did not propagate to nonirradiated regions and exhibited a refractory period of about 10 min following a BL pulse. Fluence-response relationships for the electrical and growth responses provide correlational evidence that the plasma-membrane depolarization reflects an event in the transduction chain of this light-growth response.

  2. Ultraviolet Laser SQUID Microscope for GaN Blue Light Emitting Diode Testing

    Energy Technology Data Exchange (ETDEWEB)

    Daibo, M [Department of Electrical and Electronic Engineering, Faculty of Engineering, Iwate University, Morioka 020-8551 (Japan); Kamiwano, D [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan); Kurosawa, T [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan); Yoshizawa, M [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan); Tayama, N [Department of Electrical and Electronic Engineering, Faculty of Engineering, Iwate University, Morioka 020-8551 (Japan)

    2006-06-01

    We carried out non-contacting measurements of photocurrent distributions in GaN blue light emitting diode (LED) chips using our newly developed ultraviolet (UV) laser SQUID microscope. The UV light generates the photocurrent, and then the photocurrent induces small magnetic fields around the chip. An off-axis arranged HTS-SQUID magnetometer is employed to detect a vector magnetic field whose typical amplitude is several hundred femto-tesla. Generally, it is difficult to obtain Ohmic contacts for p-type GaN because of the low hole concentration in the p-type epitaxial layer and the lack of any available metal with a higher work function compared with the p-type GaN. Therefore, a traditional probecontacted electrical test is difficult to conduct for wide band gap semiconductors without an adequately annealed electrode. Using the UV-laser SQUID microscope, the photocurrent can be measured without any electrical contact. We show the photocurrent vector map which was reconstructed from measured magnetic fields data. We also demonstrate how we found the position of a defect of the electrical short circuits in the LED chip.

  3. Enhanced algae growth in both phototrophic and mixotrophic culture under blue light.

    Science.gov (United States)

    Das, Probir; Lei, Wang; Aziz, Siti Sarah; Obbard, Jeffrey Philip

    2011-02-01

    Biomass productivity and fatty acid methyl esters (FAME) derived from intracellular lipid of a Nannochloropsis sp. isolated from Singapore's coastal waters were studied under different light wavelengths and intensities. Nannochloropsis sp., was grown in both phototrophic and mixotrophic (glycerol as the carbon source) culture conditions in three primary monochromatic light wavelengths, i.e., red, green and blue LEDs, and also in white LED. The maximum specific growth rate (μ) for LEDs was blue>white>green>red. Nannochloropsis sp. achieved a μ of 0.64 and 0.66 d(-1) in phototrophic and mixotrophic cultures under blue lighting, respectively. The intracellular fatty acid composition of Nannochloropsis sp. varied between cultures exposed to different wavelengths, although the absolute fatty acid content did differ significantly. Maximum FAME yield from Nannochloropsis sp. was 20.45% and 15.11% of dry biomass weight equivalent under photo- and mixotrophic culture conditions respectively for cultures exposed to green LED (550 nm). However, maximum volumetric FAME yield was achieved for phototrophic and mixotrophic cultures (i.e., 55.13 and 111.96 mg/l, respectively) upon cell exposure to blue LED (470 nm) due to highest biomass productivity. It was calculated that incremental exposure of light intensity over the cell growth cycle saves almost 20% of the energy input relative to continuous illumination for a given light intensity.

  4. Spontaneous mutation 7B-1 in tomato impairs blue light-induced stomatal opening.

    Science.gov (United States)

    Hlavinka, Jan; Nauš, Jan; Fellner, Martin

    2013-08-01

    It was reported earlier that 7B-1 mutant in tomato (Solanum lycopersicum L.), an ABA overproducer, is defective in blue light (BL) signaling leading to BL-specific resistance to abiotic and biotic stresses. In this work, we examine responses of stomata to blue, red and white lights, fusicoccin, anion channel blockers (anthracene-9-carboxylic acid; 9-AC and niflumic acid; NIF) and ABA. Our results showed that the aperture of 7B-1 stomata does not increase in BL, suggesting that 7B-1 mutation impairs an element of BL signaling pathway involved in stomatal opening. Similar stomatal responses of 7B-1 and wild type (WT) to fusicoccin or 9-AC points out that activity of H(+)-ATPase and 9-AC-sensitive anion channels per se is not likely affected by the mutation. Since 9-AC restored stomatal opening of 7B-1 in BL, it seems that 9-AC and BL could block similar type of anion channels. The stomata of both genotypes did not respond to NIF neither in darkness nor in any light conditions tested. In light, 9-AC but not NIF restored stomatal opening inhibited by ABA in WT and 7B-1. We suggest that in comparison to WT, the activity of S-type anion channels in 7B-1 is more promoted by increased ABA content, and less reduced by BL, because of the mutant resistance to BL.

  5. Role of L-arginine in the biological effects of blue light

    Science.gov (United States)

    Makela, Anu M.

    2005-11-01

    Arginine, a semi-essential amino acid, and metabolites of arginine exert multiple biological effects. It has been known that arginine causes the release of various hormones such as insulin, glucagon, growth hormone, prolactin, and adrenal catecholamines. Arginine infusion also produces vasodilation, and in the kidney increased plasma flow accompanied by increases in glomerular filtration rate (GFR). Recent studies have showed that blue and red light irradiation in vitro and in vivo can increase production of nitric oxide (NO), superoxide anion, and related reactive oxygen species (ROS). These then can modulate the production and secretion of several cytokines and other mediators and play an important role as regulatory mediators in signaling processes which can then modulate the production, mobilization and homing of stem cells. It is proposed that some of the therapeutic effects of light can be considered to be due to the changes in the metabolism of L-arginine. The regulation of L-arginine turnover by the use of light at blue wavelengths between 400nm and 510nm can be the explanation for some of the observed effects of blue light: lowering of blood pressure, pain killing effect, regulating insulin production, anti-inflammatory action, and possible effects on the release and homing of stem cells.

  6. Evidence for Tautomerisation of Glutamine in BLUF Blue Light Receptors by Vibrational Spectroscopy and Computational Chemistry.

    Science.gov (United States)

    Domratcheva, Tatiana; Hartmann, Elisabeth; Schlichting, Ilme; Kottke, Tilman

    2016-03-07

    BLUF (blue light sensor using flavin) domains regulate the activity of various enzymatic effector domains in bacteria and euglenids. BLUF features a unique photoactivation through restructuring of the hydrogen-bonding network as opposed to a redox reaction or an isomerization of the chromophore. A conserved glutamine residue close to the flavin chromophore plays a central role in the light response, but the underlying modification is still unclear. We labelled this glutamine with (15)N in two representative BLUF domains and performed time-resolved infrared double difference spectroscopy. The assignment of the signals was conducted by extensive quantum chemical calculations on large models with 187 atoms reproducing the UV-vis and infrared signatures of BLUF photoactivation. In the dark state, the comparatively low frequency of 1,667 cm(-1) is assigned to the glutamine C=O accepting a hydrogen bond from tyrosine. In the light state, the signature of a tautomerised glutamine was extracted with the C=N stretch at ~1,691 cm(-1) exhibiting the characteristic strong downshift by (15)N labelling. Moreover, an indirect isotope effect on the flavin C4=O stretch was found. We conclude that photoactivation of the BLUF receptor does not only involve a rearrangement of hydrogen bonds but includes a change in covalent bonds of the protein.

  7. Blue-light digital communication in underwater environments utilizing orbital angular momentum

    Science.gov (United States)

    Baghdady, Joshua; Miller, Keith; Osler, Sean; Morgan, Kaitlyn; Li, Wenzhe; Johnson, Eric; Cochenour, Brandon

    2016-05-01

    Underwater optical communication has recently become the topic of much investigation as the demands for underwater data transmission have rapidly grown in recent years. The need for reliable, high-speed, secure underwater communication has turned increasingly to blue-light optical solutions. The blue-green visible wavelength window provides an attractive solution to the problem of underwater data transmission thanks to its low attenuation, where traditional RF solutions used in free-space communications collapse. Beginning with GaN laser diodes as the optical source, this work explores the encoding and transmission of digital data across underwater environments of varying turbidities. Given the challenges present in an underwater environment, such as the mechanical and optical turbulences that make proper alignment difficult to maintain, it is desirable to achieve extremely high data rates in order to allow the time window of alignment between the transmitter and receiver to be as small as possible. In this paper, work is done to increase underwater data rates through the use of orbital angular momentum. Results are shown for a range of data rates across a variety of channel types ranging in turbidity from that of a clear ocean to a dirty harbor.

  8. Guard cell chloroplasts are essential for blue light-dependent stomatal opening in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Noriyuki Suetsugu

    Full Text Available Blue light (BL induces stomatal opening through the activation of H+-ATPases with subsequent ion accumulation in guard cells. In most plant species, red light (RL enhances BL-dependent stomatal opening. This RL effect is attributable to the chloroplasts of guard cell, the only cells in the epidermis possessing this organelle. To clarify the role of chloroplasts in stomatal regulation, we investigated the effects of RL on BL-dependent stomatal opening in isolated epidermis, guard cell protoplasts, and intact leaves of Arabidopsis thaliana. In isolated epidermal tissues and intact leaves, weak BL superimposed on RL enhanced stomatal opening while BL alone was less effective. In guard cell protoplasts, RL enhanced BL-dependent H+-pumping and DCMU, a photosynthetic electron transport inhibitor, eliminated this effect. RL enhanced phosphorylation levels of the H+-ATPase in response to BL, but this RL effect was not suppressed by DCMU. Furthermore, DCMU inhibited both RL-induced and BL-dependent stomatal opening in intact leaves. The photosynthetic rate in leaves correlated positively with BL-dependent stomatal opening in the presence of DCMU. We conclude that guard cell chloroplasts provide ATP and/or reducing equivalents that fuel BL-dependent stomatal opening, and that they indirectly monitor photosynthetic CO2 fixation in mesophyll chloroplasts by absorbing PAR in the epidermis.

  9. Characterisation of blue-light stimulated luminescence components in different quartz samples: implications for dose measurement

    Energy Technology Data Exchange (ETDEWEB)

    Jain, M. E-mail: mayank.jain@risoe.dk; Murray, A.S.; Boetter-Jensen, L

    2003-10-01

    Over the last few years, we have become increasingly confident that quartz is a reliable natural dosimeter for sediment dating. Nevertheless, there is only a limited understanding of the behaviour of the different components of optically stimulated luminescence (OSL) from quartz. Recent single-aliquot dose-evaluation protocols seem to be relatively free of complications when applied to quartz dominated by the fast OSL component coming from 325 deg. C TL region, but this may not be true for quartz in which other components are more significant. An adequate understanding of how different OSL components behave during various measurement cycles is critical to ensuring that our dose evaluation protocols are robust and it is also important to our interpretation of the variation of apparent dose with optical stimulation time for identification of partial bleaching. We report here the principal results from measurement of (a) sensitisation, (b) thermal stability, (c) recuperation, and (d) infrared response as a function of stimulation temperature from 3 different samples of sedimentary quartz selected on the basis of relative OSL contribution from different blue light stimulated linearly modulated (LM-OSL) components. We then discuss the implications of these characteristics for dose assessment using the single aliquot regeneration dose protocol.

  10. Evidence for Tautomerisation of Glutamine in BLUF Blue Light Receptors by Vibrational Spectroscopy and Computational Chemistry

    Science.gov (United States)

    Domratcheva, Tatiana; Hartmann, Elisabeth; Schlichting, Ilme; Kottke, Tilman

    2016-01-01

    BLUF (blue light sensor using flavin) domains regulate the activity of various enzymatic effector domains in bacteria and euglenids. BLUF features a unique photoactivation through restructuring of the hydrogen-bonding network as opposed to a redox reaction or an isomerization of the chromophore. A conserved glutamine residue close to the flavin chromophore plays a central role in the light response, but the underlying modification is still unclear. We labelled this glutamine with 15N in two representative BLUF domains and performed time-resolved infrared double difference spectroscopy. The assignment of the signals was conducted by extensive quantum chemical calculations on large models with 187 atoms reproducing the UV-vis and infrared signatures of BLUF photoactivation. In the dark state, the comparatively low frequency of 1,667 cm−1 is assigned to the glutamine C=O accepting a hydrogen bond from tyrosine. In the light state, the signature of a tautomerised glutamine was extracted with the C=N stretch at ~1,691 cm−1 exhibiting the characteristic strong downshift by 15N labelling. Moreover, an indirect isotope effect on the flavin C4=O stretch was found. We conclude that photoactivation of the BLUF receptor does not only involve a rearrangement of hydrogen bonds but includes a change in covalent bonds of the protein. PMID:26947391

  11. Evidence for Tautomerisation of Glutamine in BLUF Blue Light Receptors by Vibrational Spectroscopy and Computational Chemistry

    Science.gov (United States)

    Domratcheva, Tatiana; Hartmann, Elisabeth; Schlichting, Ilme; Kottke, Tilman

    2016-03-01

    BLUF (blue light sensor using flavin) domains regulate the activity of various enzymatic effector domains in bacteria and euglenids. BLUF features a unique photoactivation through restructuring of the hydrogen-bonding network as opposed to a redox reaction or an isomerization of the chromophore. A conserved glutamine residue close to the flavin chromophore plays a central role in the light response, but the underlying modification is still unclear. We labelled this glutamine with 15N in two representative BLUF domains and performed time-resolved infrared double difference spectroscopy. The assignment of the signals was conducted by extensive quantum chemical calculations on large models with 187 atoms reproducing the UV-vis and infrared signatures of BLUF photoactivation. In the dark state, the comparatively low frequency of 1,667 cm-1 is assigned to the glutamine C=O accepting a hydrogen bond from tyrosine. In the light state, the signature of a tautomerised glutamine was extracted with the C=N stretch at ~1,691 cm-1 exhibiting the characteristic strong downshift by 15N labelling. Moreover, an indirect isotope effect on the flavin C4=O stretch was found. We conclude that photoactivation of the BLUF receptor does not only involve a rearrangement of hydrogen bonds but includes a change in covalent bonds of the protein.

  12. LOW-POTENTIAL ELECTROSYNTHESIS OF CONDUCTING AND ELECTROACTIVE OLIGOCATECHOLBORANE WITH BLUE LIGHT-EMITTING PROPERTIES

    Institute of Scientific and Technical Information of China (English)

    Bao-yang Lu; Shuai Chen; Lei-qiang Qin; Yao Huang; Jing-kun Xu

    2013-01-01

    Novel conducting oligocatecholborane (OCOB) with electrical conductivity of 3.73 × 10-2 S cm-1 was successfully synthesized by low-potential electropolymerization of catecholborane (COB) in boron trifluoride diethyl etherate at 0.70 V versus Ag/AgC1.FT-IR and 1H-NMR spectra,together with the computational results,proved that COB was polymerized through the coupling at C(4) and C(5) positions and the reactive B-H bond was stable during the electrochemical polymerization.The resulting product was mainly composed of oligomers with short chain lengths by GPC and mass spectral results.The as-formed OCOB film showed good electrochemistry in monomer-free electrolytes with the electrochromic property from opaque blue to sap green.Fluorescence studies indicated that soluble OCOB can emit bright blue light under excitation of 365 nm UV light with the maximum emission at 396 nm and a fluorescence quantum yield of 0.21.The deposited OCOB also exhibited favorable thermal stability and smooth and compact morphology even at high magnifications.

  13. Light based anti-infectives: ultraviolet C irradiation, photodynamic therapy, blue light, and beyond

    Science.gov (United States)

    Yin, Rui; Dai, Tianhong; Avci, Pinar; Jorge, Ana Elisa Serafim; de Melo, Wanessa CMA; Vecchio, Daniela; Huang, Ying-Ying; Gupta, Asheesh; Hamblin, Michael R

    2013-01-01

    Owing to the worldwide increase in antibiotic resistance, researchers are investigating alternative anti-infective strategies to which it is supposed microorganisms will be unable to develop resistance. Prominent among these strategies, is a group of approaches which rely on light to deliver the killing blow. As is well known, ultraviolet light, particularly UVC (200–280nm), is germicidal, but it has not been much developed as an anti-infective approach until recently, when it was realized that the possible adverse effects to host tissue were relatively minor compared to its high activity in killing pathogens. Photodynamic therapy is the combination of non-toxic photosensitizing dyes with harmless visible light that together produce abundant destructive reactive oxygen species (ROS). Certain cationic dyes or photosensitizers have good specificity for binding to microbial cells while sparing host mammalian cells and can be used for treating many localized infections, both superficial and even deep-seated by using fiber optic delivered light. Many microbial cells are highly sensitive to killing by blue light (400–470 nm) due to accumulation of naturally occurring photosensitizers such as porphyrins and flavins. Near infrared light has also been shown to have antimicrobial effects against certain species. Clinical applications of these technologies include skin, dental, wound, stomach, nasal, toenail and other infections which are amenable to effective light delivery. PMID:24060701

  14. Analysis of Pigeon (Columba) Ovary Transcriptomes to Identify Genes Involved in Blue Light Regulation.

    Science.gov (United States)

    Wang, Ying; Ding, Jia-Tong; Yang, Hai-Ming; Yan, Zheng-Jie; Cao, Wei; Li, Yang-Bai

    2015-01-01

    Monochromatic light is widely applied to promote poultry reproductive performance, yet little is currently known regarding the mechanism by which light wavelengths affect pigeon reproduction. Recently, high-throughput sequencing technologies have been used to provide genomic information for solving this problem. In this study, we employed Illumina Hiseq 2000 to identify differentially expressed genes in ovary tissue from pigeons under blue and white light conditions and de novo transcriptome assembly to construct a comprehensive sequence database containing information on the mechanisms of follicle development. A total of 157,774 unigenes (mean length: 790 bp) were obtained by the Trinity program, and 35.83% of these unigenes were matched to genes in a non-redundant protein database. Gene description, gene ontology, and the clustering of orthologous group terms were performed to annotate the transcriptome assembly. Differentially expressed genes between blue and white light conditions included those related to oocyte maturation, hormone biosynthesis, and circadian rhythm. Furthermore, 17,574 SSRs and 533,887 potential SNPs were identified in this transcriptome assembly. This work is the first transcriptome analysis of the Columba ovary using Illumina technology, and the resulting transcriptome and differentially expressed gene data can facilitate further investigations into the molecular mechanism of the effect of blue light on follicle development and reproduction in pigeons and other bird species.

  15. Analysis of Pigeon (Columba Ovary Transcriptomes to Identify Genes Involved in Blue Light Regulation.

    Directory of Open Access Journals (Sweden)

    Ying Wang

    Full Text Available Monochromatic light is widely applied to promote poultry reproductive performance, yet little is currently known regarding the mechanism by which light wavelengths affect pigeon reproduction. Recently, high-throughput sequencing technologies have been used to provide genomic information for solving this problem. In this study, we employed Illumina Hiseq 2000 to identify differentially expressed genes in ovary tissue from pigeons under blue and white light conditions and de novo transcriptome assembly to construct a comprehensive sequence database containing information on the mechanisms of follicle development. A total of 157,774 unigenes (mean length: 790 bp were obtained by the Trinity program, and 35.83% of these unigenes were matched to genes in a non-redundant protein database. Gene description, gene ontology, and the clustering of orthologous group terms were performed to annotate the transcriptome assembly. Differentially expressed genes between blue and white light conditions included those related to oocyte maturation, hormone biosynthesis, and circadian rhythm. Furthermore, 17,574 SSRs and 533,887 potential SNPs were identified in this transcriptome assembly. This work is the first transcriptome analysis of the Columba ovary using Illumina technology, and the resulting transcriptome and differentially expressed gene data can facilitate further investigations into the molecular mechanism of the effect of blue light on follicle development and reproduction in pigeons and other bird species.

  16. Short Blue Light Pulses (30 Min) in the Morning Support a Sleep-Advancing Protocol in a Home Setting.

    Science.gov (United States)

    Geerdink, Moniek; Walbeek, Thijs J; Beersma, Domien G M; Hommes, Vanja; Gordijn, Marijke C M

    2016-10-01

    Many people in our modern civilized society sleep later on free days compared to work days. This discrepancy in sleep timing will lead to so-called 'social jetlag' on work days with negative consequences for performance and health. Light therapy in the morning is often proposed as the most effective method to advance the circadian rhythm and sleep phase. However, most studies focus on direct effects on the circadian system and not on posttreatment effects on sleep phase and sleep integrity. In this placebo-controlled home study we investigated if blue light, rather than amber light therapy, can phase shift the sleep phase along with the circadian rhythm with preservation of sleep integrity and performance. We selected 42 participants who suffered from 'social jetlag' on workdays. Participants were randomly assigned to either high-intensity blue light exposure or amber light exposure (placebo) with similar photopic illuminance. The protocol consisted of 14 baseline days without sleep restrictions, 9 treatment days with either 30-min blue light pulses or 30-min amber light pulses in the morning along with a sleep advancing scheme and 7 posttreatment days without sleep restrictions. Melatonin samples were taken at days 1, 7, 14 (baseline), day 23 (effect treatment), and day 30 (posttreatment). Light exposure was recorded continuously. Sleep was monitored through actigraphy. Performance was measured with a reaction time task. As expected, the phase advance of the melatonin rhythm from day 14 to day 23 was significantly larger in the blue light exposure group, compared to the amber light group (84 min ± 51 (SD) and 48 min ± 47 (SD) respectively; t36 = 2.23, p light group compared to slightly later in the amber light group (-21 min ± 33 (SD) and +12 min ± 33 (SD) respectively; F1,35 = 9.20, p light group compared to the blue light group during sleep in the treatment period (F1,32 = 4.40, p light treatment (F1,13 = 17.1, p light condition (F1

  17. The role of mislocalized phototransduction in photoreceptor cell death of retinitis pigmentosa.

    Directory of Open Access Journals (Sweden)

    Takeshi Nakao

    Full Text Available Most of inherited retinal diseases such as retinitis pigmentosa (RP cause photoreceptor cell death resulting in blindness. RP is a large family of diseases in which the photoreceptor cell death can be caused by a number of pathways. Among them, light exposure has been reported to induce photoreceptor cell death. However, the detailed mechanism by which photoreceptor cell death is caused by light exposure is unclear. In this study, we have shown that even a mild light exposure can induce ectopic phototransduction and result in the acceleration of rod photoreceptor cell death in some vertebrate models. In ovl, a zebrafish model of outer segment deficiency, photoreceptor cell death is associated with light exposure. The ovl larvae show ectopic accumulation of rhodopsin and knockdown of ectopic rhodopsin and transducin rescue rod photoreceptor cell death. However, knockdown of phosphodiesterase, the enzyme that mediates the next step of phototransduction, does not. So, ectopic phototransduction activated by light exposure, which leads to rod photoreceptor cell death, is through the action of transducin. Furthermore, we have demonstrated that forced activation of adenylyl cyclase in the inner segment leads to rod photoreceptor cell death. For further confirmation, we have also generated a transgenic fish which possesses a human rhodopsin mutation, Q344X. This fish and rd10 model mice show photoreceptor cell death caused by adenylyl cyclase. In short, our study indicates that in some RP, adenylyl cyclase is involved in photoreceptor cell death pathway; its inhibition is potentially a logical approach for a novel RP therapy.

  18. Germafluorene conjugated copolymer——synthesis and applications in blue-light-emitting diodes and host materials

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A germafluorene-fluorene copolymer was successfully obtained via Suzuki polymerization.The ger-manium containing copolymer has an efficient blue light emission under the ultraviolet irradiation and its single layer EL device showed the highest brightness of 2630 cd/m2 at 7.8 V and the highest effi-ciency of 0.301 lm/W at 6.2 V.The copolymer can also serve as the host material for phosphorescent metal complexes with the maximum brightness of 15600 cd/m2 and the quantum efficiency of 8.5%.The results are quite promising and promise that as its analogs of fluorene and silafluorene,germafluorene is an excellent building block for blue light-emitting polymers and host materials.

  19. Germafluorene conjugated copolymer——synthesis and applications in blue-light-emitting diodes and host materials

    Institute of Scientific and Technical Information of China (English)

    CHEN RunFeng; ZHU Rui; ZHENG Chao; LIU ShuJuan; FAN QuLi; HUANG Wei

    2009-01-01

    A germafluorene-fluorene copolymer was successfully obtained via Suzuki polymerization. The ger-manium containing copolymer has an efficient blue light emission under the ultraviolet irradiation and its single layer EL device showed the highest brightness of 2630 cd/m2 at 7.8 V and the highest effi-ciency of 0.301 Im/W at 6.2 V. The copolymer can also serve as the host material for phosphorescent metal complexes with the maximum brightness of 15600 cd/m2 and the quantum efficiency of 8.5%. The results are quite promising and promise that as its analogs of fluorene and silafluorene, germafluorene is an excellent building block for blue light-emitting polymers and host materials.

  20. Blue light is required for survival of the tomato phytochrome-deficient aurea mutant and the expression of four nuclear genes coding for plastidic proteins.

    Science.gov (United States)

    Oelmüller, R; Kendrick, R E

    1991-02-01

    When dark-grown aurea mutant tomato seedlings which lack more than 95% of the phytochrome present in isogenic wild-type seedlings are kept in white or blue light, four nuclear-encoded transcripts coding for plastidic proteins (the light-harvesting chlorophyll a/b-binding protein of photosystem I and II [cab-PSII], plastocyanin and subunit 2 of photosystem I) are present in comparable amounts. These transcript levels in red light are strongly reduced in aurea seedlings when compared with those of wild type. Thus, blue light is required for normal expression of these genes in the mutant, while red light alone is not sufficient. Red light-grown aurea seedlings are very sensitive to blue light, even 10 minutes of blue light every day suffices to cause a measurable increase in cab-PSII transcript level. The action of blue light on the expression of cab-PSII in the mutant is under phytochrome control. After 8 days of blue light, phytochrome is almost as effective in inducing cab-PSII mRNA as in the isogenic wild type, whereas after 8 days of red light, only a small phytochrome response was observed in the mutant. It is concluded that blue light sensitizes the mutant to the residual phytochrome which allows normal gene expression and survival of the mutant under daylight conditions.

  1. Cone photoreceptors are the main targets for gene therapy of NPHP5 (IQCB1) or NPHP6 (CEP290) blindness: generation of an all-cone Nphp6 hypomorph mouse that mimics the human retinal ciliopathy.

    Science.gov (United States)

    Cideciyan, Artur V; Rachel, Rivka A; Aleman, Tomas S; Swider, Malgorzata; Schwartz, Sharon B; Sumaroka, Alexander; Roman, Alejandro J; Stone, Edwin M; Jacobson, Samuel G; Swaroop, Anand

    2011-04-01

    Leber congenital amaurosis (LCA), a severe autosomal recessive childhood blindness, is caused by mutations in at least 15 genes. The most common molecular form is a ciliopathy due to NPHP6 (CEP290) mutations and subjects have profound loss of vision. A similarly severe phenotype occurs in the related ciliopathy NPHP5 (IQCB1)-LCA. Recent success of retinal gene therapy in one form of LCA prompted the question whether we know enough about human NPHP5 and NPHP6 disease to plan such treatment. We determined that there was early-onset rapid degeneration of rod photoreceptors in young subjects with these ciliopathies. Rod outer segment (OS) lamination, when detectable, was disorganized. Retinal pigment epithelium lipofuscin accumulation indicated that rods had existed in the past in most subjects. In contrast to early rod losses, the all-cone human fovea in NPHP5- and NPHP6-LCA of all ages retained cone nuclei, albeit with abnormal inner segments and OS. The rd16 mouse, carrying a hypomorphic Nphp6 allele, was a good model of the rod-dominant human extra-foveal retina. Rd16 mice showed normal genesis of photoreceptors, including the formation of cilia, followed by abnormal elaboration of OS and rapid degeneration. To produce a model of the all-cone human fovea in NPHP6-LCA, we generated rd16;Nrl-/- double-mutant mice. They showed substantially retained cone photoreceptors with disproportionate cone function loss, such as in the human disease. NPHP5- and NPHP6-LCA across a wide age spectrum are thus excellent candidates for cone-directed gene augmentation therapy, and the rd16;Nrl-/- mouse is an appropriate model for pre-clinical proof-of-concept studies.

  2. Liquid-Crystalline Star-Shaped Supergelator Exhibiting Aggregation-Induced Blue Light Emission.

    Science.gov (United States)

    Pathak, Suraj Kumar; Pradhan, Balaram; Gupta, Monika; Pal, Santanu Kumar; Sudhakar, Achalkumar Ammathnadu

    2016-09-13

    A family of closely related star-shaped stilbene-based molecules containing an amide linkage are synthesized, and their self-assembly in liquid-crystalline and gel states was investigated. The number and position of the peripheral alkyl tails were systematically varied to understand the structure-property relation. Interestingly, one of the molecules with seven peripheral chains was bimesomorphic, exhibiting columnar hexagonal and columnar rectangular phases, whereas the rest of them stabilized the room-temperature columnar hexagonal phase. The self-assembly of these molecules in liquid-crystalline and organogel states is extremely sensitive to the position and number of alkoxy tails in the periphery. Two of the compounds with six and seven peripheral tails exhibited supergelation behavior in long-chain hydrocarbon solvents. One of these compounds with seven alkyl chains was investigated further, and it has shown higher stability and moldability in the gel state. The xerogel of the same compound was characterized with the help of extensive microscopic and X-ray diffraction studies. The nanofibers in the xerogel are found to consist of molecules arranged in a lamellar fashion. Furthermore, this compound shows very weak emission in solution but an aggregation-induced emission property in the gel state. Considering the dearth of solid-state blue-light-emitting organic materials, this molecular design is promising where the self-assembly and emission in the aggregated state can be preserved. The nonsymmetric design lowers the phase-transition temperatures.The presence of an amide bond helps to stabilize columnar packing over a long range because of its polarity and intermolecular hydrogen bonding in addition to promoting organogelation.

  3. Influence of Light Emitting Diode-Derived Blue Light Overexposure on Mouse Ocular Surface.

    Science.gov (United States)

    Lee, Hyo Seok; Cui, Lian; Li, Ying; Choi, Ji Suk; Choi, Joo-Hee; Li, Zhengri; Kim, Ga Eon; Choi, Won; Yoon, Kyung Chul

    2016-01-01

    To investigate the influence of overexposure to light emitting diode (LED)-derived light with various wavelengths on mouse ocular surface. LEDs with various wavelengths were used to irradiate C57BL/6 mice at an energy dose of 50 J/cm2, twice a day, for 10 consecutive days. The red, green, and blue groups represented wavelengths of 630 nm, 525 nm, and 410 nm, respectively. The untouched group (UT) was not exposed to LED light and served as the untreated control. Tear volume, tear film break-up time (TBUT), and corneal fluorescein staining scores were measured on days 1, 3, 5, 7, and 10. Levels of interferon (IFN)-γ, interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α were measured in the cornea and conjunctiva using a multiplex immunobead assay at day 10. Levels of malondialdehyde (MDA) were measured with an enzyme-linked immunosorbent assay. Flow cytometry, 2'7'-dichlorofluorescein diacetate (DCF-DA) assay, histologic analysis, immunohistochemistry with 4-hydroxynonenal, and terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL) staining were also performed. TBUT of the blue group showed significant decreases at days 7 and 10, compared with the UT and red groups. Corneal fluorescein staining scores significantly increased in the blue group when compared with UT, red, and green groups at days 5, 7, and 10. A significant increase in the corneal levels of IL-1β and IL-6 was observed in the blue group, compared with the other groups. The blue group showed significantly increased reactive oxygen species production in the DCF-DA assay and increased inflammatory T cells in the flow cytometry. A significantly increased TUNEL positive cells was identified in the blue group. Overexposure to blue light with short wavelengths can induce oxidative damage and apoptosis to the cornea, which may manifest as increased ocular surface inflammation and resultant dry eye.

  4. Sugar and organic acid accumulation in guard cells of Vicia faba in response to red and blue light

    Energy Technology Data Exchange (ETDEWEB)

    Talbott, L.D.; Zeiger, E. (Univ. of California, Los Angeles, CA (United States))

    1993-08-01

    Changes in neutral sugar and organic acid content of guard cells were quantitated by high-performance liquid chromatography during stomatal opening in different light qualities. Sonicated Vicia faba epidermal peels were irradiated with 10 [mu]mol m[sup [minus]2] s[sup [minus]1] of blue light, a fluence rate insufficient for the activation of guard cell photosynthesis, or 125 [mu]mol m[sup [minus]2] s[sup [minus]1] of red light, in the presence of 1mM KCl, 0.1 mM CaCl[sub 2]. The low-fluence-rate blue light stimulated an average net stomatal opening of 4.7 [mu]m in 2 h, whereas the saturating fluence rate of red light stimulated an average net opening of 3.8 [mu]m in 2 h. Under blue light, the malate content of guard cells increased to 173% of the initial level during the first 30 min of opening and declined as opening continued. Sucrose levels continuously rose throughout the blue light-stimulated opening, reaching 215% of the initial level after 2 h. The starch hydrolysis products maltose and maltotriose remained elevated at all times. Under red light, guard cells showed very little increase in organic acid or maltose levels, whereas sucrose levels increased to 208% of the initial level after 2 h. Total measured organic metabolite concentrations were correlated with stomatal apertures in all cases except where substantial malate increases occurred. These results support the hypothesis that light quality modulates alternative mechanisms of osmotic accumulation guard cells, including potassium uptake, photosynthetic sugar production, and starch breakdown. 29 refs., 5 figs., 2 tab.

  5. High-efficiency pyrene-based blue light emitting diodes: Aggregation suppression using a calixarene 3D-scaffold

    KAUST Repository

    Chan, Khaileok

    2012-01-01

    An efficient blue light emitting diode based on solution processable pyrene-1,3-alt-calix[4]arene is demonstrated, providing a record current efficiency of 10.5 cd A -1 in a simple non-doped OLED configuration. Complete suppression of pyrene aggregation in the solid state is achieved by controlling chromophore dispersion using the 1,3-alt-calix[4]arene scaffold. © 2012 The Royal Society of Chemistry.

  6. Nrl is required for rod photoreceptor development.

    Science.gov (United States)

    Mears, A J; Kondo, M; Swain, P K; Takada, Y; Bush, R A; Saunders, T L; Sieving, P A; Swaroop, A

    2001-12-01

    The protein neural retina leucine zipper (Nrl) is a basic motif-leucine zipper transcription factor that is preferentially expressed in rod photoreceptors. It acts synergistically with Crx to regulate rhodopsin transcription. Missense mutations in human NRL have been associated with autosomal dominant retinitis pigmentosa. Here we report that deletion of Nrl in mice results in the complete loss of rod function and super-normal cone function, mediated by S cones. The photoreceptors in the Nrl-/- retina have cone-like nuclear morphology and short, sparse outer segments with abnormal disks. Analysis of retinal gene expression confirms the apparent functional transformation of rods into S cones in the Nrl-/- retina. On the basis of these findings, we postulate that Nrl acts as a 'molecular switch' during rod-cell development by directly modulating rod-specific genes while simultaneously inhibiting the S-cone pathway through the activation of Nr2e3.

  7. Analysis of the effects of blue light on morphofunctional status of in vitro cultured blastocysts from mice carrying gene of enhanced green fluorescent protein (EGFP).

    Science.gov (United States)

    Sakharova, N Yu; Mezhevikina, L M; Smirnov, A A; Vikhlyantseva, E F

    2014-05-01

    We studied the effect of blue light (440-490 nm) on the development of late blastocysts of mice carrying the gene of enhanced green fluorescent protein (EGFP). Exposure to blue light for 20 min reduced adhesive properties of blastocysts and their capacity to form primary colonies consisting of the cells of inner cell mass, trophoblast, and extraembryonic endoderm. The negative effects of blue light manifested in morphological changes in the primary colonies and impairment of differentiation and migration of cells of the trophoblast and extraembryonic endoderm. The problems of cell-cell interaction and inductive influences of the inner cell mass on other cell subpopulations are discussed. EGFP blastocysts were proposed as the model for evaluation of the mechanisms underlying the effects of blue light as the major negative factor of visible light used in in vitro experiments on mammalian embryos.

  8. Spectroscopic analysis of the dark relaxation process of a photocycle in a sensor of blue light using FAD (BLUF) protein Slr1694 of the cyanobacterium Synechocystis sp. PCC6803.

    Science.gov (United States)

    Hasegawa, Koji; Masuda, Shinji; Ono, Taka-Aki

    2005-01-01

    Slr1694 is a BLUF (sensor of blue light using flavin adenine dinucleotide) protein and a putative photoreceptor in the cyanobacterium Synechocystis sp. PCC6803. Illumination of Slr1694 induced a signaling light state concurrent with a red shift in the UV-visible absorption of flavin, and formation of the bands from flavin and apo-protein in the light-minus-dark Fourier transform infrared (FTIR) difference spectrum. Replacement of Tyr8 with phenylalanine abolished these changes. The light state relaxed to the ground dark state, during which the FTIR bands decayed monophasically. These bands were classifiable into three groups according to their decay rates. The C4=O stretching bands of a flavin isoalloxazine ring had the highest decay rate, which corresponded to that of the absorption red shift. The result indicated that the hydrogen bonding at C4=O is responsible for the UV-visible red shift, consistent with the results of density functional calculation. All FTIR bands and the red shift decayed at the same slower rate in deuterated Slr1694. These results indicated that the dark relaxation from the light state is limited by proton transfer. In contrast, a constrained light state formed under dehydrated conditions decayed much more slowly with no deuteration effects. A photocycle mechanism involving the proton transfer was proposed.

  9. In vitro and in vivo antimicrobial activity of combined therapy of silver nanoparticles and visible blue light against Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Nour El Din S

    2016-04-01

    Full Text Available Suzanne Nour El Din,1 Tarek A El-Tayeb,2 Khaled Abou-Aisha,1 Mohamed El-Azizi1 1Department of Microbiology, Immunology and Biotechnology, Faculty of Pharmacy and Biotechnology, German University in Cairo, 2National Institute for Laser Enhanced Sciences, Cairo University, Cairo, Egypt Abstract: Silver nanoparticles (AgNPs have been used as potential antimicrobial agents against resistant pathogens. We investigated the possible therapeutic use of AgNPs in combination with visible blue light against a multidrug resistant clinical isolate of Pseudomonas aeruginosa in vitro and in vivo. The antibacterial activity of AgNPs against P. aeruginosa (1×105 colony forming unit/mL was investigated at its minimal inhibitory concentration (MIC and sub-MIC, alone and in combination with blue light at 460 nm and 250 mW for 2 hours. The effect of this combined therapy on the treated bacteria was then visualized using transmission electron microscope. The therapy was also assessed in the prevention of biofilm formation by P. aeruginosa on AgNP-impregnated gelatin biopolymer discs. Further, in vivo investigations were performed to evaluate the efficacy of the combined therapy to prevent burn-wound colonization and sepsis in mice and, finally, to treat a real infected horse with antibiotic-unresponsive chronic wound. The antimicrobial activity of AgNPs and visible blue light was significantly enhanced (P<0.001 when both agents were combined compared to each agent alone when AgNPs were tested at MIC, 1/2, or 1/4 MIC. Transmission electron microscope showed significant damage to the cells that were treated with the combined therapy compared to other cells that received either the AgNPs or blue light. In addition, the combined treatment significantly (P<0.001 inhibited biofilm formation by P. aeruginosa on gelatin discs compared to each agent individually. Finally, the combined therapy effectively treated a horse suffering from a chronic wound caused by mixed

  10. Phototransferred thermoluminescence from alpha-Al sub 2 O sub 3 :C using blue light emitting diodes

    CERN Document Server

    Bulur, E

    1999-01-01

    Phototransferred thermoluminescence (PTTL) from alpha-Al sub 2 O sub 3 :C single crystals was studied using a blue light emitting diode (LED) for phototransfer of charges from deep traps to the main dosimetry trap. The dose response was found to be linear in the region from approx 5 mGy to approx 5 Gy. It was observed that the corresponding deep traps were located near 500 deg. C and heating to temperatures >600 deg. C removes the PTTL effect induced by the light from the blue LED. The thermal activation energy of the source traps involved in the PTTL production was calculated as 3.23 eV.

  11. Electrosynthesis of Chirality Conducting Poly[N-(9-fluorenylmethoxycarbonyl)-L-phenylalanine] with Good Blue Light-Emitting Properties

    Institute of Scientific and Technical Information of China (English)

    来存远; 郭文娟; 唐新德; 裴梅山

    2012-01-01

    Poly[N-(9-fluorenylmethoxycarbonyl)-L-phenylalanine] (PN9FPA) films with good fluorescence properties and chirality were prepared electrochemically by direct anodic oxidation of N-(9-fluorenylmethoxycarbonyl)- L-phenylalanine (N9FPA) in boron trifluoride diethyletherate (BFEE). Fourier transform infrared spectroscopy measurement showed that the polymerization of N9FPA occurred mainly at the C(2) and C(7) positions. The fluo- rescence spectra indicated that PN9FPA films were blue-light emitters. In addition, the structures and properties of the monomer and the polymers were characterized and evaluated with CV, UV, TGA and SEM.

  12. Inhibition of blue-light-dependent binding of 14-3-3 proteins to phototropins by hydrogen peroxide

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao; SHIMAZAKI Kenichiro

    2005-01-01

    @@ Phototropins, following the discovery of phytochromes[1,2] and cryptochromes[3,4], are the most recently characterized blue-light (BL) receptors in plants. The N- terminal regions of the proteins contain two light oxygen and voltage (LOV)――LOV1 and LOV2, which belong to PAS domain involved in protein-protein interaction and ligand binding, possessing non-covalent binding sites for the chromophore FMN[5]. The C-terminal regions contain Ser/Thr kinase domains[6].

  13. Ciliary photoreceptors in the cerebral eyes of a protostome larva

    Directory of Open Access Journals (Sweden)

    Passamaneck Yale J

    2011-03-01

    Full Text Available Abstract Background Eyes in bilaterian metazoans have been described as being composed of either ciliary or rhabdomeric photoreceptors. Phylogenetic distribution, as well as distinct morphologies and characteristic deployment of different photopigments (ciliary vs. rhabdomeric opsins and transduction pathways argue for the co-existence of both of these two photoreceptor types in the last common bilaterian ancestor. Both receptor types exist throughout the Bilateria, but only vertebrates are thought to use ciliary photoreceptors for directional light detection in cerebral eyes, while all other invertebrate bilaterians studied utilize rhabdomeric photoreceptors for this purpose. In protostomes, ciliary photoreceptors that express c-opsin have been described only from a non-visual deep-brain photoreceptor. Their homology with vertebrate rods and cones of the human eye has been hypothesized to represent a unique functional transition from non-visual to visual roles in the vertebrate lineage. Results To test the hypothesis that protostome cerebral eyes employ exclusively rhabdomeric photoreceptors, we investigated the ultrastructure of the larval eyes in the brachiopod Terebratalia transversa. We show that these pigment-cup eyes consist of a lens cell and a shading pigment cell, both of which are putative photoreceptors, deploying a modified, enlarged cilium for light perception, and have axonal connections to the larval brain. Our investigation of the gene expression patterns of c-opsin, Pax6 and otx in these eyes confirms that the larval eye spots of brachiopods are cerebral eyes that deploy ciliary type photoreceptors for directional light detection. Interestingly, c-opsin is also expressed during early embryogenesis in all potential apical neural cells, becoming restricted to the anterior neuroectoderm, before expression is initiated in the photoreceptor cells of the eyes. Coincident with the expression of c-opsin in the presumptive neuroectoderm

  14. A New Proof of Concept in Bacterial Reduction: Antimicrobial Action of Violet-Blue Light (405 nm in Ex Vivo Stored Plasma

    Directory of Open Access Journals (Sweden)

    Michelle Maclean

    2016-01-01

    Full Text Available Bacterial contamination of injectable stored biological fluids such as blood plasma and platelet concentrates preserved in plasma at room temperature is a major health risk. Current pathogen reduction technologies (PRT rely on the use of chemicals and/or ultraviolet light, which affects product quality and can be associated with adverse events in recipients. 405 nm violet-blue light is antibacterial without the use of photosensitizers and can be applied at levels safe for human exposure, making it of potential interest for decontamination of biological fluids such as plasma. As a pilot study to test whether 405 nm light is capable of inactivating bacteria in biological fluids, rabbit plasma and human plasma were seeded with bacteria and treated with a 405 nm light emitting diode (LED exposure system (patent pending. Inactivation was achieved in all tested samples, ranging from low volumes to prebagged plasma. 99.9% reduction of low density bacterial populations (≤103 CFU mL−1, selected to represent typical “natural” contamination levels, was achieved using doses of 144 Jcm−2. The penetrability of 405 nm light, permitting decontamination of prebagged plasma, and the nonrequirement for photosensitizing agents provide a new proof of concept in bacterial reduction in biological fluids, especially injectable fluids relevant to transfusion medicine.

  15. A New Proof of Concept in Bacterial Reduction: Antimicrobial Action of Violet-Blue Light (405 nm) in Ex Vivo Stored Plasma

    Science.gov (United States)

    Maclean, Michelle; Anderson, John G.; MacGregor, Scott J.; White, Tracy

    2016-01-01

    Bacterial contamination of injectable stored biological fluids such as blood plasma and platelet concentrates preserved in plasma at room temperature is a major health risk. Current pathogen reduction technologies (PRT) rely on the use of chemicals and/or ultraviolet light, which affects product quality and can be associated with adverse events in recipients. 405 nm violet-blue light is antibacterial without the use of photosensitizers and can be applied at levels safe for human exposure, making it of potential interest for decontamination of biological fluids such as plasma. As a pilot study to test whether 405 nm light is capable of inactivating bacteria in biological fluids, rabbit plasma and human plasma were seeded with bacteria and treated with a 405 nm light emitting diode (LED) exposure system (patent pending). Inactivation was achieved in all tested samples, ranging from low volumes to prebagged plasma. 99.9% reduction of low density bacterial populations (≤103 CFU mL−1), selected to represent typical “natural” contamination levels, was achieved using doses of 144 Jcm−2. The penetrability of 405 nm light, permitting decontamination of prebagged plasma, and the nonrequirement for photosensitizing agents provide a new proof of concept in bacterial reduction in biological fluids, especially injectable fluids relevant to transfusion medicine. PMID:27774337

  16. How can EPR spectroscopy help to unravel molecular mechanisms of flavin-dependent photoreceptors?

    Directory of Open Access Journals (Sweden)

    Daniel eNohr

    2015-09-01

    Full Text Available Electron paramagnetic resonance (EPR spectroscopy is a well-established spectroscopic method for the examination of paramagnetic molecules. Proteins can contain paramagnetic moieties in form of stable cofactors, transiently formed intermediates, or spin labels artificially introduced to cysteine sites. The focus of this review is to evaluate potential scopes of application of EPR to the emerging field of optogenetics. The main objective for EPR spectroscopy in this context is to unravel the complex mechanisms of light-active proteins, from their primary photoreaction to downstream signal transduction. An overview of recent results from the family of flavin-containing, blue-light dependent photoreceptors is given. In detail, mechanistic similarities and differences are condensed from the three classes of flavoproteins, the cryptochromes, LOV (Light-oxygen-voltage, and BLUF (blue-light using FAD domains. Additionally, a concept that includes spin-labeled proteins and examination using modern pulsed EPR is introduced, which allows for a precise mapping of light-induced conformational changes.

  17. Efficient Generation of Red and Blue Light in a Dual-Structure Periodically Poled LiTaO3 Crystal

    Institute of Scientific and Technical Information of China (English)

    何京良; 胡小鹏; 祝世宁; 朱永元; 闵乃本

    2003-01-01

    We demonstrate the efficient generation of red light at 671 nm and blue light at 447nm from a diode-pumped Q-switched 1342 nm Nd:YVO4 laser together with a periodically poled LiTaO3 (PPLT) crystal. The sample used in this experiment is a dual-structure PPLT crystal with the period of 14.9 μm for the second harmonic generation and that of 4.9μm for the third harmonic generation. The red and blue light, with the respective average power of 752 m W and 153 m W were obtained in a single path under an average fundamental power of 1.74 W, corresponding to the conversion efficiencies of 43.2% and 8.8%, respectively. These results indicate that the dual-structure PPLT can be used to construct a compact and efficient all-solid-state red-and-blue dual-wavelength laser.

  18. Neonates with sickle cell disease are vulnerable to blue light phototherapy-induced oxidative stress and proinflammatory cytokine elevations.

    Science.gov (United States)

    Chaudhari, Hemakshi; Goyal, Sameer; Patil, Chandragouda

    2016-11-01

    Sickle cell disease is a frequent genetic anomaly characterized by altered molecular structure of hemoglobin resulting into crescent-like deformation of the red blood corpuscles. Neonatal jaundice is a frequent co-morbidity in sickle cell disease. Phototherapy induces isomerization of bilirubin rendering it extractable through urine and hence it is used as a routine treatment of neonatal jaundice. An exposure to light phototherapy as a treatment of neonatal jaundice induces oxidative stress. It is hypothesized that such exposure of neonates with sickle cell disease to the blue light phototherapy as a treatment of neonatal jaundice induces severe oxidative stress and increases the levels of proinflammatory cytokines. This hypothesis is supported with two case studies of sickle cell disease suffering neonates who were exposed to blue light phototherapy to treat jaundice. In both these cases, exposure to phototherapy induced oxidative stress (increased lipid peroxidation and superoxide dismutase, slight change in activity of catalase and GSH) and elevated the levels of proinflammatory cytokine (TNFα, IL-1, and IL-6) in the sickle cell disease suffering neonates. These observations warrant further investigations to determine the consequences and clinical significance of the blue phototherapy-induced oxidative and proinflammatory stress in Sickle cell disease suffering neonates exposed to phototherapy as a treatment of jaundice.

  19. Plastid movement impaired 2, a new gene involved in normal blue-light-induced chloroplast movements in Arabidopsis.

    Science.gov (United States)

    Luesse, Darron R; DeBlasio, Stacy L; Hangarter, Roger P

    2006-08-01

    Chloroplasts move in a light-dependent manner that can modulate the photosynthetic potential of plant cells. Identification of genes required for light-induced chloroplast movement is beginning to define the molecular machinery that controls these movements. In this work, we describe plastid movement impaired 2 (pmi2), a mutant in Arabidopsis (Arabidopsis thaliana) that displays attenuated chloroplast movements under intermediate and high light intensities while maintaining a normal movement response under low light intensities. In wild-type plants, fluence rates below 20 micromol m(-2) s(-1) of blue light lead to chloroplast accumulation on the periclinal cell walls, whereas light intensities over 20 micromol m(-2) s(-1) caused chloroplasts to move toward the anticlinal cell walls (avoidance response). However, at light intensities below 75 micromol m(-2) s(-1), chloroplasts in pmi2 leaves move to the periclinal walls; 100 micromol m(-2) s(-1) of blue light is required for chloroplasts in pmi2 to move to the anticlinal cell walls, indicating a shift in the light threshold for the avoidance response in the mutant. The pmi2 mutation has been mapped to a gene that encodes a protein of unknown function with a large coiled-coil domain in the N terminus and a putative P loop. PMI2 shares sequence and structural similarity with PMI15, another unknown protein in Arabidopsis that, when mutated, causes a defect in chloroplast avoidance under high-light intensities.

  20. Determination of blue-light-induced infrared absorption based on mode-matching efficiency in an optical parametric oscillator

    Science.gov (United States)

    Wang, Yajun; Yang, Wenhai; Li, Zhixiu; Zheng, Yaohui

    2017-02-01

    Non-classical squeezed states of light at a compatible atomic wavelength have a potential application in quantum information protocols for quantum states delaying or storaging. An optical parametric oscillator (OPO) with periodically poled potassium titanyl phosphate (PPKTP) is the most effective method for generating this squeezed state. However, it is a challege for the nonlinear interaction in PPKTP crystal at the D1 line of rubidium atomic, due to a strong blue-light-induced infrared absorption (BLIIRA). In this paper, we report an indirect measurement method for the BLIIRA through measuring the mode-matching efficiency in an optical parametric oscillator. In contrast to previous works, our method is not limited by the absolute power variation induced from the change of frequency conversion loss and the impedance matching originated from the change of absorption loss. Therefore, the measurement process is performed at the phase-matching condition. The measured results show that BLIIRA coefficient is quadratic dependence of blue light intensity below 1 kW per square centimeter in our PPKTP device, which will provide important basis for optimizing squeezed state generation at 795 nm.

  1. Understanding Cone Photoreceptor Cell Death in Achromatopsia.

    Science.gov (United States)

    Carvalho, Livia S; Vandenberghe, Luk H

    2016-01-01

    Colour vision is only achieved in the presence of healthy and functional cone photoreceptors found in the retina. It is an essential component of human vision and usually the first complaint patients undergoing vision degeneration have is the loss of daylight colour vision. Therefore, an understanding of the biology and basic mechanisms behind cone death under the degenerative state of retinal dystrophies and how the activation of the apoptotic pathway is triggered will provide valuable knowledge. It will also have broader applications for a spectrum of visual disorders and will be critical for future advances in translational research.

  2. The 7B-1 mutation in tomato (Solanum lycopersicum L.) confers a blue light-specific lower sensitivity to coronatine, a toxin produced by Pseudomonas syringae pv. tomato.

    Science.gov (United States)

    Bergougnoux, Véronique; Hlavácková, Vladimíra; Plotzová, Renáta; Novák, Ondrej; Fellner, Martin

    2009-01-01

    The spontaneous mutant 7B-1 in tomato (Solanum lycopersicum=Lycopersicon esculentum) is a photoperiod-dependent male-sterile mutant previously reported as resistant to various abiotic stresses specifically under blue light. Since this finding improved the potential of 7B-1's use in breeding programmes, its susceptibility to stress induced by coronatine (COR), the phytotoxine produced by several Pseudomonas syringae strains, was assessed in this study. The 7B-1 mutant was found to be less sensitive than the corresponding wild type (WT) to COR treatment in a blue light-dependent manner. Treatment of WT and 7B-1 plants with COR induced a strong accumulation of salicylic acid (SA), jasmonic acid (JA), and abscisic acid (ABA) in hypocotyls. Interestingly, accumulation of ABA and SA in the 7B-1 mutant was distinctly greater than in WT, especially in blue light. Based on the cross-talk between SA- and JA-signalling pathways, expression analysis of NPR1 and COI1 genes, respectively involved in these pathways, was investigated in COR-stressed plants. The blue light-specific lower sensitivity of 7B-1 plants to COR was found to be associated with blue light-specific overexpression of the NPR1 gene. These data suggest that the SA-dependent NPR1-dependent pathway could be involved in the lower sensitivity of the 7B-1 mutant to COR. The role of anthocyanins and ABA accumulation during the response to COR is also discussed in the present study.

  3. Effects of UV-B radiation on tetraspores of Chondrus ocellatus Holm (Rhodophyta), and effects of red and blue light on repair of UV-B-induced damage

    Science.gov (United States)

    Ju, Qing; Xiao, Hui; Wang, You; Tang, Xuexi

    2015-05-01

    We evaluated the effects of red and blue light on the repair of UV-B radiation-induced damage in tetraspores of Chondrus ocellatus Holm. Tetraspores of C. ocellatus were treated with different UV-B radiation levels (0, 36, 72, 108, 144 and 180 J/m2), and thereafter subjected to PAR, darkness, or red or blue light during a 2-h repair stage, each day for 48 days. The diameters and cellular contents of cyclobutane pyrimidine dimmers (CPDs), chlorophyll a (Chl a), phycoerythrin, and UV-B-absorbing mycosporinelike amino acids (MAAs) contents of the tetraspores were determined. Our results show that low doses of UV-B radiation (36 and 72 J/m2) promoted the growth of C. ocellatus; however, increased UV-B radiation gradually reduced the C. ocellatus growth (greater than 72 J/m2). The MAAs (palythine and asterina-330) in C. ocellatus were detected and analyzed by LC/MS. Our results suggest that moderate red light could induce the growth of this alga in aquaculture. In addition, photorepair was inhibited by red light, so there may be some other DNA repair mechanism activated by red light. Blue light promoted the activity of DNA photolyase, greatly improving remediation efficiency. Red and blue lights were found to reduce the capacity of C. ocellatus to form MAAs. Therefore, PAR, red light, and blue light play different roles during the repair processes for damage induced by UV-B radiation.

  4. Augmentation of macular pigment following implantation of blue light-filtering intraocular lenses at the time of cataract surgery.

    Science.gov (United States)

    Nolan, John M; O'Reilly, Philip; Loughman, James; Stack, Jim; Loane, Edward; Connolly, Eithne; Beatty, Stephen

    2009-10-01

    (Photo)-oxidative stress is believed to play a role in the pathogenesis of age-related macular degeneration (AMD), with the threshold for retinal damage being lowest for short-wavelength (blue) light. Macular pigment (MP), consisting of the carotenoids lutein (L), zeaxanthin (Z) and meso-Z, has a maximum absorption at 460 nm and protects the retina from (photo)-oxidative injury. This study was designed to investigate whether the blue light-filtering properties of the Alcon AcrySof Natural intraocular lens (ANIOL) implanted during cataract surgery affects MP optical density (MPOD). Forty-two patients scheduled for cataract surgery were recruited for the study. These patients all had a preoperative best corrected visual acuity rating (BCVAR) of at least 0.5 (logMAR) in the study eye. The patients were randomized to have either the standard Alcon AcrySof three-piece acrylic intraocular lens (AIOL) (controls) or the ANIOL implanted at the time of cataract surgery. The spatial profile of MPOD (i.e., at 0.25 degrees, 0.5 degrees, 1.0 degrees, and 1.75 degrees eccentricity) was measured with customized heterochromatic flicker photometry (cHFP) 1 week before and 1 week after surgery, and at 3, 6, and 12 months after surgery. Serum concentrations of L and Z were also measured at each study visit. There was a highly significant and positive correlation between all MPODs (e.g., at 0.25 degrees) recorded 1 week before and after surgery in eyes with an AIOL implant (r = 0.915, P 0.05). There were no significant time or lens effects observed for serum L over the study period (P > 0.05). There was a significant time effect for serum Z over the study period (P 0.05). Customized HFP can reliably measure the MPOD spatial profile in the presence of lens opacity, and cataract surgery does not artifactually alter MPOD readings. This study also provides evidence that implanting an IOL that filters blue light is associated with augmentation of MPOD in the absence of raised serum

  5. PHOTORECEPTOR DEGENERATION IN A MOUNTAIN LION CUB (PUMA CONCOLOR).

    Science.gov (United States)

    DiSalvo, Andrew R; Reilly, Christopher M; Wiggans, K Tomo; Woods, Leslie W; Wack, Ray F; Clifford, Deana L

    2016-12-01

    An orphaned 4-mo-old female mountain lion cub ( Puma concolor ) was captured along the coastline in Montaña de Oro State Park in Los Osos, California, USA. Following suspicion that the cub was visually impaired, ophthalmic examination revealed diffuse bilateral retinal atrophy. Due to a poor prognosis, humane euthanasia was elected. Necropsy and histopathological findings were consistent with photoreceptor degeneration. Based on the cub's signalment, history, and histopathology, a genetic or nutritional etiology was suspected, with the former etiology more strongly supported. To the authors' knowledge, this is the first report of photoreceptor degeneration in a wild felid and should be considered in cases of blindness.

  6. Sputtering of ZnO buffer layer on Si for GaN blue light emitting materials

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The preparation of high quality ZnO/Si substrates for the growth of GaN blue light emitting materials is considered. ZnO thin films have been deposited on Si(100) and Si(111) substrates by conventional magnetron sputtering. Morphology, crystallinity and c-axis preferred orientation of ZnO thin films have been investigated by transmitting electron microscopy (TEM), X-ray diffraction (XRD) and X-ray rocking curve (XRC). It is proved that the ZnO thin films have perfect structure. The full-width-at-half-maximum (FWHM) of the ZnO(002) XRC of these films is about 1°, while the minimum is 0.353°. This result is better than the minimum FWHM (about 2°) reported by other research groups. Moreover, comparison and discussion are given on film structure of ZnO/Si(100) and ZnO/Si(111)

  7. Sputtering of ZnO buffer layer on Si for GaN blue light emitting materials

    Institute of Scientific and Technical Information of China (English)

    贺洪波; 范正修; 姚振钰; 汤兆胜

    2000-01-01

    The preparation of high quality ZnO/Si substrates for the growth of GaN blue light emitting materials is considered. ZnO thin films have been deposited on Si (100) and Si (111) substrates by conventional magnetron sputtering. Morphology, crystallinity and c-axis preferred orientation of ZnO thin films have been investigated by transmitting electron microscopy (TEM), X-ray diffraction (XRD) and X-ray rocking curve (XRC). It is proved that the ZnO thin films have perfect structure. The full-width-at-half-maximum (FWHM) of the ZnO(002) XRC of these films is about 1°, while the minimum is 0.353°. This result is better than the minimum FWHM (about 2°) reported by other research groups. Moreover, comparison and discussion are given on film structure of ZnO/Si(100) and ZnO/Si(111).

  8. Chemical magnetoreception: bird cryptochrome 1a is excited by blue light and forms long-lived radical-pairs.

    Directory of Open Access Journals (Sweden)

    Miriam Liedvogel

    Full Text Available Cryptochromes (Cry have been suggested to form the basis of light-dependent magnetic compass orientation in birds. However, to function as magnetic compass sensors, the cryptochromes of migratory birds must possess a number of key biophysical characteristics. Most importantly, absorption of blue light must produce radical pairs with lifetimes longer than about a microsecond. Cryptochrome 1a (gwCry1a and the photolyase-homology-region of Cry1 (gwCry1-PHR from the migratory garden warbler were recombinantly expressed and purified from a baculovirus/Sf9 cell expression system. Transient absorption measurements show that these flavoproteins are indeed excited by light in the blue spectral range leading to the formation of radicals with millisecond lifetimes. These biophysical characteristics suggest that gwCry1a is ideally suited as a primary light-mediated, radical-pair-based magnetic compass receptor.

  9. Comparative Study of Lettuce and Radish Grown Under Red and Blue Light-Emitting Diodes (LEDs) and White Fluorescent Lamps

    Science.gov (United States)

    Mickens, Matthew A.

    2012-01-01

    Growing vegetable crops in space will be an essential part of sustaining astronauts during long-term missions. To drive photosynthesis, red and blue light-emitting diodes (LEDs) have attracted attention because of their efficiency, longevity, small size, and safety. In efforts to optimize crop production, there have also been recent interests in analyzing the subtle effects of green light on plant growth, and to determine if it serves as a source of growth enhancement or suppression. A comparative study was performed on two short cycle crops of lettuce (Outredgeous) and radish (Cherry Bomb) grown under two light treatments. The first treatment being red and blue LEDs, and the second treatment consisting of white fluorescent lamps which contain a portion of green light. In addition to comparing biomass production, physiological characterizations were conducted on how the light treatments influence morphology, water use, chlorophyll content, and the production of A TP within plant tissues.

  10. Increasing the extraction efficiency of blue light emitting diodes via laser patterned Ga-polar p-GaN surface

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Zhiyuan; Liu, Duo; Zhang, Baitao; He, Jingliang; Liu, Hong; Xu, Xiangang [State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100 (China)

    2011-09-15

    We report here the laser patterned Ga-polar p-GaN surface to improve the light extraction efficiency of GaN based blue light emitting diodes (LEDs) by using a pulsed UV laser in combination with a mirror scanner. The patterns created on p-GaN are confirmed to be suitable for light extraction and a 34.9% enhancement of the electroluminescent (EL) emission intensity has been obtained. Detailed discussions on the effects of laser on LEDs and the angular dependence of the emission profile are also provided. This method could be extended to other III-V LEDs and LEDs on SiC for fabricating highly efficient LEDs. The schematic of laser fabrication equipment, SEM image of patterned p-GaN surface and guided-modes extraction photograph of patterned GaN epilayer. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Electrical and Optical Properties of InGaN/AIGaN Double Heterostructure Blue Light-Emitting Diodes

    Institute of Scientific and Technical Information of China (English)

    SHEN Bo; SHI Hong-Tao; ZHANG Rong; CHEN Zhi-Zhong; ZHENG You-Dou

    2001-01-01

    Electrical and optical properties of InGaN/AlGaN double heterostructure blue light-emitting diodes were inves tigated. Measurement of the forward bias current-voltage behaviour of the device demonstrated a departure from the Shockley model of a p-n diode, and it was observed that the dominant mechanism of carrier transport across the junction is associated with carrier tunnelling. Electroluminescence experiments indicated that there was a main emission band around 2.80eV and a relatively weaker peak at 3.2eV. A significant blueshift of the optical emission band was observed, which was consistent with the tunnelling character of electrical characteris tics. Furthermore, the degradation in I - V characteristics and the low resistance ohmic short of the device were observed.

  12. Performance improvement of InGaN blue light-emitting diodes with several kinds of electron-blocking layers

    Institute of Scientific and Technical Information of China (English)

    Chen Jun; Fan Guang-Han; Zhang Yun-Yan; Pang Wei; Zheng Shu-Wen; Yao Guang-Rui

    2012-01-01

    The performance of lnGaN blue light-emitting diodes(LEDs)with different kinds of electron-blocking layers is investigated numerically.We compare the simulated emission spectra,electron and hole concentrations,euergy band diagrams,electrostatic fields,and internal quantum efficiencies of the LEDs.The LED using A1GaN with gradually increasing Al content from 0% to 20% as the electron-blocking layer(EBL)has a strong spectrum intensity,mitigates efficiency droop,and possesses higher output power compared with the LEDs with the other three types of EBLs.These advantages could be because of the lower electron leakage current and more effective hole injection.The optical performance of the specifically designed LED is also improved in the case of large injection current.

  13. On Dispersion in Visual Photoreceptors

    NARCIS (Netherlands)

    Stavenga, D.G.; Barneveld, H.H. van

    1975-01-01

    An idealized visual pigment absorbance spectrum is used together with a Kramers-Kronig dispersion relation to calculate the contribution of the visual pigment to the refractive index of the fly photoreceptor. It appears that an absorption coefficient of 0.010 µm-1 results in a refractive index varia

  14. Photoreceptors: unconventional ways of seeing

    OpenAIRE

    Diaz, Naryttza N.; Sprecher, Simon G.

    2011-01-01

    Animals perceive light typically by photoreceptor neurons assembled in eyes, but some also use non-eye photosensory neurons. Multidendritic neurons in the body wall of Drosophila larvae have now been shown to use an unconventional phototransduction mechanism to sense light.

  15. Photoreceptor proteins from purple bacteria

    NARCIS (Netherlands)

    Hendriks, J.; van der Horst, M.A.; Chua, T.K.; Ávila Pérez, M.; van Wilderen, L.J.; Alexandre, M.T.A.; Groot, M.-L.; Kennis, J.T.M.; Hellingwerf, K.J.; Hunter, C.N.; Daldal, F.; Thurnauer, M.C.; Beatty, J.T.

    2009-01-01

    Purple bacteria contain representatives of four of the six main families of photoreceptor proteins: phytochromes, BLUF domain containing proteins, xanthopsins (i.e., photoactive yellow proteins), and phototropins (containing one or more light, oxygen, or voltage (LOV) domains). Most of them have a

  16. Predawn and high intensity application of supplemental blue light decreases the quantum yield of PSII and enhances the amount of phenolic acids, flavonoids, and pigments in Lactuca sativa.

    Science.gov (United States)

    Ouzounis, Theoharis; Razi Parjikolaei, Behnaz; Fretté, Xavier; Rosenqvist, Eva; Ottosen, Carl-Otto

    2015-01-01

    To evaluate the effect of blue light intensity and timing, two cultivars of lettuce [Lactuca sativa cv. "Batavia" (green) and cv. "Lollo Rossa" (red)] were grown in a greenhouse compartment in late winter under natural light and supplemental high pressure sodium (SON-T) lamps yielding 90 (±10) μmol m(-2) s(-1) for up to 20 h, but never between 17:00 and 21:00. The temperature in the greenhouse compartments was 22/11°C day/night, respectively. The five light-emitting diode (LED) light treatments were Control (no blue addition), 1B 06-08 (Blue light at 45 μmol m(-2) s(-1) from 06:00 to 08:00), 1B 21-08 (Blue light at 45 μmol m(-2) s(-1) from 21:00 to 08:00), 2B 17-19 (Blue at 80 μmol m(-2) s(-1) from 17:00 to 19:00), and 1B 17-19 (Blue at 45 μmol m(-2) s(-1) from 17:00 to 19:00). Total fresh and dry weight was not affected with additional blue light; however, plants treated with additional blue light were more compact. The stomatal conductance in the green lettuce cultivar was higher for all treatments with blue light compared to the Control. Photosynthetic yields measured with chlorophyll fluorescence showed different response between the cultivars; in red lettuce, the quantum yield of PSII decreased and the yield of non-photochemical quenching increased with increasing blue light, whereas in green lettuce no difference was observed. Quantification of secondary metabolites showed that all four treatments with additional blue light had higher amount of pigments, phenolic acids, and flavonoids compared to the Control. The effect was more prominent in red lettuce, highlighting that the results vary among treatments and compounds. Our results indicate that not only high light level triggers photoprotective heat dissipation in the plant, but also the specific spectral composition of the light itself at low intensities. However, these plant responses to light are cultivar dependent.

  17. Occupational exposure of welders to ultraviolet and "blue light" radiation emitted during TIG and MMA welding based on field measuremants

    Directory of Open Access Journals (Sweden)

    Agnieszka Wolska

    2013-02-01

    Full Text Available Background: The aim of the study was to present the results of welders' occupational exposure to "blue light" and UV radiation carried out at industrial workstations during TIG and MMA welding. Materials and methods: Measurements were performed at 13 workstations (TIG welding: 6; MMA welding: 7, at which different welding parameters and materials were used. The radiation level was measured using a wide-range radiometer and a set of detectors, whose spectral responses were adequately fit to particular hazard under study. The measurement points corresponded with the location of eye and hand. Results: The highest values of eye irradiance were found for aluminum TIG welding. Effective irradiance of actinic UV was within the range Es = 7.79-37.6 W/m2; UVA total irradiance, EUVA = 18-53.1 W/m2 and effective blue-light irradiance EB = 35-67 W/m2. The maximum allowance time ranged from 1.7 to 75 s, which means that in some cases even unintentional very short eye exposure can exceed MPE. Conclusions: The influence of welded material and the type of electrode coating on the measured radiation level were evidenced. The exceeded value of MPE for photochemical hazard arising for the eyes and skin was found at all measured workstations. Welders should use appropriately the eye and face protective equipment and avoid direct staring at welding arc when starting an arcwelding operation. Besides, the lack of head and neck skin protection can induce acute and chronic harmful health effects. Therefore, an appropriate wear of personal protective equipment is essential for welders' health. Med Pr 2013;64(1:69–82

  18. Photocurrent response of B12As2 crystals to blue light, and its temperature- dependent electrical characterizations

    Directory of Open Access Journals (Sweden)

    R. Gul

    2016-02-01

    Full Text Available With the global shortage of 3He gas, researchers worldwide are looking for alternative materials for detecting neutrons. Among the candidate materials, semiconductors are attractive because of their light weight and ease in handling. Currently, we are looking into the suitability of boron arsenide (B12As2 for this specific application. As the first step in evaluating the material qualitatively, the photo-response of B12As2 bulk crystals to light with different wavelengths was examined. The crystals showed photocurrent response to a band of 407- and 470- nm blue light. The maximum measured photoresponsivity and the photocurrent density at 0.7 V for 470 nm blue light at room temperature were 0.25 A ⋅ W−1 and 2.47 mA ⋅ cm−2, respectively. In addition to photo current measurements, the electrical properties as a function of temperature (range: 50-320 K were measured. Reliable data were obtained for the low-temperature I-V characteristics, the temperature dependence of dark current and its density, and the resistivity variations with temperature in B12As2 bulk crystals. The experiments showed an exponential dependence on temperature for the dark current, current density, and resistivity; these three electrical parameters, respectively, had a variation of a few nA to μA, 1-100 μA ⋅ cm−2 and 7.6x105-7.7x103 Ω ⋅ cm, for temperature increasing from 50 K to 320 K. The results from this study reported the first photoresponse and demonstrated that B12As2 is a potential candidate for thermal-neutron detectors.

  19. RED AND BLUE LIGHT-STIMULATED PROTON EFFLUX BY EPIDERMAL LEAF-CELLS OF THE ARGENTEUM MUTANT OF PISUM-SATIVUM

    NARCIS (Netherlands)

    STAAL, M; ELZENGA, JTM; VANELK, AG; PRINS, HBA; VANVOLKENBURGH, E

    1994-01-01

    Light stimulates leaf expansion in dicotyledons by increasing apoplastic acidification, cell wall loosening and solute accumulation for turgor maintenance. Red and blue light enhance growth via different photosystems, but the cellular location and modes of action of these systems is not known. Here,

  20. Hexaminolevulinate blue-light cystoscopy in non-muscle-invasive bladder cancer: review of the clinical evidence and consensus statement on appropriate use in the USA

    NARCIS (Netherlands)

    Daneshmand, S.; Schuckman, A.K.; Bochner, B.H.; Cookson, M.S.; Downs, T.M.; Gomella, L.G.; Grossman, H.B.; Kamat, A.M.; Konety, B.R.; Lee, C.T.; Pohar, K.S.; Pruthi, R.S.; Resnick, M.J.; Smith, N.D.; Witjes, J.A.; Schoenberg, M.P.; Steinberg, G.D.

    2014-01-01

    Hexaminolevulinate (HAL) is a tumour photosensitizer that is used in combination with blue-light cystoscopy (BLC) as an adjunct to white-light cystoscopy (WLC) in the diagnosis and management of non-muscle-invasive bladder cancer (NMIBC). Since being licensed in Europe in 2005, HAL has been used in

  1. Fluorescent blue lights, injecting drug use and related health risk in public conveniences: findings from a qualitative study of micro-injecting environments.

    Science.gov (United States)

    Parkin, Stephen; Coomber, Ross

    2010-07-01

    This paper presents findings relating to injecting drug users' experiences and opinions of public toilets illuminated with fluorescent blue lights and presents an empirical assessment of the intended deterrent effect of such installations. Data analysis identified that blue lights deterred less than half the sample interviewed. Furthermore over half (18/31) of the sample were prepared to inject in conditions specifically designed to deter injecting practice. Of these, 11 respondents were completely undeterred and 7 individuals were only partially deterred by blue light environments. These findings are discussed within the interpretative frameworks of Pierre Bourdieu's theory of habitus and symbolic violence. The authors conclude that fluorescent blue lights contribute towards the development of situated resistance by injecting drug users within a public injecting habitus; a resistance that produces and reproduces drug-related harm and is a behaviour that opposes the symbolic violence of harm reduction intervention. The paper concludes with suggestions for theory-driven practical intervention that may seek to disrupt the harmful elements of the public injecting habitus. 2010 Elsevier Ltd. All rights reserved.

  2. 100 mW of blue light at 405 nm from intracavity doubling of CW Ti:Sapphire laser utilising BiBO-crystal

    DEFF Research Database (Denmark)

    Thorhauge, Morten; Mortensen, Jesper Liltorp; Tidemand-Lichtenberg, Peter

    2006-01-01

    100 mW of coherent blue light with a wavelength of 405 nm was generated utilising a BiB3O6 (BiBO) nonlinear crystal to frequency double a Ti:Sapphire laser. Phase match curves as well as sensitivity to angular misalignment was calculated. The BiBO crystal was found to be excellent for this applic...

  3. Dose response of hydrazine - Deproteinated tooth enamel under blue light stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Yuece, Ulkue Rabia, E-mail: ulkuyuce@hotmail.co [Ankara University, Faculty of Engineering, Department of Engineering Physics, 06100, Tandogan - Ankara (Turkey); Meric, Niyazi, E-mail: meric@ankara.edu.t [Ankara University, Faculty of Engineering, Department of Engineering Physics, 06100, Tandogan - Ankara (Turkey); Atakol, Orhan, E-mail: atakol@science.ankara.edu.t [Ankara University, Science Faculty, Department of Chemistry, 06100, Tandogan - Ankara (Turkey); Yasar, Fusun, E-mail: ab121310@adalet.gov.t [Council of Forensic Medicine, Ankara Branch, Ankara (Turkey)

    2010-08-15

    The beta dose response and Optically Stimulated Luminescence (OSL) signal stability characteristics of human tooth enamel deproteinated by hydrazine reagent under blue photon stimulation are reported. Removal of the protein organic component of tooth enamel resulted in a higher OSL sensitivity and slower fading of OSL signals. The effect of chemical sample preparation on the enamel sample sensitivity is discussed and further steps to make this deproteinization treatment suitable for in vitro dose reconstruction studies are suggested.

  4. Dose-dependent collagen cross-linking of rabbit scleral tissue by blue light and riboflavin treatment probed by dynamic shear rheology.

    Science.gov (United States)

    Schuldt, Carsten; Karl, Anett; Körber, Nicole; Koch, Christian; Liu, Qing; Fritsch, Anatol W; Reichenbach, Andreas; Wiedemann, Peter; Käs, Josef A; Francke, Mike; Iseli, Hans Peter

    2015-08-01

    To determine the visco-elastic properties of isolated rabbit scleral tissue and dose-dependent biomechanical and morphological changes after collagen cross-linking by riboflavin/blue light treatment. Scleral patches from 87 adult albino rabbit eyes were examined by dynamic shear rheology. Scleral patches were treated by riboflavin and different intensities of blue light (450 nm), and the impact on the visco-elastic properties was determined by various rheological test regimes. The relative elastic modulus was calculated from non-treated and corresponding treated scleral patches, and treatments with different blue light intensities were compared. Shear rheology enables us to study the material properties of scleral tissue within physiological relevant parameters. Cross-linking treatment increased the viscous as well as the elastic modulus and changed the ratio of the elastic versus viscous proportion in scleral tissue. Constant riboflavin application combined with different blue light intensities from 12 mW/cm(2) up to 100 mW/cm(2) increased the relative elastic modulus of scleral tissue by factors up to 1.8. Further enhancement of the applied light intensity caused a decline of the relative elastic modulus. This might be due to destructive changes of the collagen bundle structure at larger light intensities, as observed by histological examination. Collagen cross-linking by riboflavin/blue light application increases the biomechanical stiffness of the sclera in a dose-dependent manner up to certain light intensities. Therefore, this treatment might be a suitable therapeutic approach to stabilize the biomechanical properties of scleral tissue in cases of pathological eye expansion. © 2014 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  5. Exploring the active site structure of photoreceptor proteins by Raman optical activity

    Science.gov (United States)

    Unno, Masashi

    2015-03-01

    Understanding protein function at the atomic level is a major challenge in a field of biophysics and requires the combined efforts of structural and functional methods. We use photoreceptor proteins as a model system to understand in atomic detail how a chromophore and a protein interact to sense light and send a biological signal. A potential technique for investigating molecular structures is Raman optical activity (ROA), which is a spectroscopic method with a high sensitivity to the structural details of chiral molecules. However, its application to photoreceptor proteins has not been reported. Thus we have constructed ROA spectrometer using near-infrared (NIR) laser excitation at 785 nm. The NIR excitation enables us to measure ROA spectra for a variety of biological samples, including photoreceptor proteins, without fluorescence from the samples. In the present study, we have applied the NIR-ROA to bacteriorhodopsin (BR) and photoactive yellow protein (PYP). BR is a light-driven proton pump and contains a protonated Schiff base of retinal as a chromophore. PYP is a blue light receptor, and this protein has the 4-hydroxycinnamyl chromophore, which is covalently linked to Cys69 through a thiolester bond. We have successfully obtained the ROA spectra of the chromophore within a protein environment. Furthermore, calculations of the ROA spectra utilizing density functional theory provide detailed structural information, such as data on out-of-plane distortions of the chromophore. The structural information obtained from the ROA spectra includes the positions of hydrogen atoms, which are usually not detected in the crystal structures of biological samples.

  6. Phycomyces MADB interacts with MADA to form the primary photoreceptor complex for fungal phototropism.

    Science.gov (United States)

    Sanz, Catalina; Rodríguez-Romero, Julio; Idnurm, Alexander; Christie, John M; Heitman, Joseph; Corrochano, Luis M; Eslava, Arturo P

    2009-04-28

    The fungus Phycomyces blakesleeanus reacts to environmental signals, including light, gravity, touch, and the presence of nearby objects, by changing the speed and direction of growth of its fruiting body (sporangiophore). Phototropism, growth toward light, shares many features in fungi and plants but the molecular mechanisms remain to be fully elucidated. Phycomyces mutants with altered phototropism were isolated approximately 40 years ago and found to have mutations in the mad genes. All of the responses to light in Phycomyces require the products of the madA and madB genes. We showed that madA encodes a protein similar to the Neurospora blue-light photoreceptor, zinc-finger protein WC-1. We show here that madB encodes a protein similar to the Neurospora zinc-finger protein WC-2. MADA and MADB interact to form a complex in yeast 2-hybrid assays and when coexpressed in E. coli, providing evidence that phototropism and other responses to light are mediated by a photoresponsive transcription factor complex. The Phycomyces genome contains 3 genes similar to wc-1, and 4 genes similar to wc-2, many of which are regulated by light in a madA or madB dependent manner. We did not detect any interactions between additional WC proteins in yeast 2-hybrid assays, which suggest that MADA and MADB form the major photoreceptor complex in Phycomyces. However, the presence of multiple wc genes in Phycomyces may enable perception across a broad range of light intensities, and may provide specialized photoreceptors for distinct photoresponses.

  7. Dlic1 deficiency impairs ciliogenesis of photoreceptors by destabilizing dynein

    Institute of Scientific and Technical Information of China (English)

    Shanshan Kong; Xinrong Du; Chao Peng; Yiming Wu; Huirong Li; Xi Jin; Ling Hou

    2013-01-01

    Cytoplasmic dynein 1 is fundamentally important for transporting a variety of essential cargoes along microtubules within eukaryotic cells.However,in mammals,few mutants are available for studying the effects of defects in dynein-controlled processes in the context of the whole organism.Here,we deleted mouse Dlic1 gene encoding DLIC1,a subunit of the dynein complex.Dlic1-/-mice are viable,but display severe photoreceptor degeneration.Ablation of Dlic1 results in ectopic accumulation of outer segment (OS) proteins,and impairs OS growth and ciliogenesis of photoreceptors by interfering with Rabll-vesicle trafficking and blocking efficient OS protein transport from Golgi to the basal body.Our studies show that Dlic1 deficiency partially blocks vesicle export from endoplasmic reticulum (ER),but seems not to affect vesicle transport from the ER to Golgi.Further mechanistic study reveals that lack of Dlic1 destabilizes dynein subunits and alters the normal subcellular distribution of dynein in photoreceptors,probably due to the impaired transport function of dynein.Our results demonstrate that Dlic1 plays important roles in ciliogenesis and protein transport to the OS,and is required for photoreceptor development and survival.The Dlic1-/-mice also provide a new mouse model to study human retinal degeneration.

  8. Photoreceptor damage following exposure to excess riboflavin.

    Science.gov (United States)

    Eckhert, C D; Hsu, M H; Pang, N

    1993-12-15

    Flavins generate oxidants during metabolism and when exposed to light. Here we report that the photoreceptor layer of retinas from black-eyed rats is reduced in size by a dietary regime containing excess riboflavin. The effect of excess riboflavin was dose-dependent and was manifested by a decrease in photoreceptor length. This decrease was due in part to a reduction in the thickness of the outer nuclear layer, a structure formed from stacked photoreceptor nuclei. These changes were accompanied by an increase in photoreceptor outer segment autofluorescence following illumination at 328 nm, a wavelength that corresponds to the excitation maxima of oxidized lipopigments of the retinal pigment epithelium.

  9. The cis-regulatory logic of the mammalian photoreceptor transcriptional network.

    Directory of Open Access Journals (Sweden)

    Timothy H-C Hsiau

    Full Text Available The photoreceptor cells of the retina are subject to a greater number of genetic diseases than any other cell type in the human body. The majority of more than 120 cloned human blindness genes are highly expressed in photoreceptors. In order to establish an integrative framework in which to understand these diseases, we have undertaken an experimental and computational analysis of the network controlled by the mammalian photoreceptor transcription factors, Crx, Nrl, and Nr2e3. Using microarray and in situ hybridization datasets we have produced a model of this network which contains over 600 genes, including numerous retinal disease loci as well as previously uncharacterized photoreceptor transcription factors. To elucidate the connectivity of this network, we devised a computational algorithm to identify the photoreceptor-specific cis-regulatory elements (CREs mediating the interactions between these transcription factors and their target genes. In vivo validation of our computational predictions resulted in the discovery of 19 novel photoreceptor-specific CREs near retinal disease genes. Examination of these CREs permitted the definition of a simple cis-regulatory grammar rule associated with high-level expression. To test the generality of this rule, we used an expanded form of it as a selection filter to evolve photoreceptor CREs from random DNA sequences in silico. When fused to fluorescent reporters, these evolved CREs drove strong, photoreceptor-specific expression in vivo. This study represents the first systematic identification and in vivo validation of CREs in a mammalian neuronal cell type and lays the groundwork for a systems biology of photoreceptor transcriptional regulation.

  10. Analysis of circadian properties and healthy levels of blue light from smartphones at night.

    Science.gov (United States)

    Oh, Ji Hye; Yoo, Heeyeon; Park, Hoo Keun; Do, Young Rag

    2015-06-18

    This study proposes representative figures of merit for circadian and vision performance for healthy and efficient use of smartphone displays. The recently developed figures of merit for circadian luminous efficacy of radiation (CER) and circadian illuminance (CIL) related to human health and circadian rhythm were measured to compare three kinds of commercial smartphone displays. The CIL values for social network service (SNS) messenger screens from all three displays were higher than 41.3 biolux (blx) in a dark room at night, and the highest CIL value reached 50.9 blx. These CIL values corresponded to melatonin suppression values (MSVs) of 7.3% and 11.4%, respectively. Moreover, smartphone use in a bright room at night had much higher CIL and MSV values (58.7 ~ 105.2 blx and 15.4 ~ 36.1%, respectively). This study also analyzed the nonvisual and visual optical properties of the three smartphone displays while varying the distance between the screen and eye and controlling the brightness setting. Finally, a method to possibly attenuate the unhealthy effects of smartphone displays was proposed and investigated by decreasing the emitting wavelength of blue LEDs in a smartphone LCD backlight and subsequently reducing the circadian effect of the display.

  11. Analysis of circadian properties and healthy levels of blue light from smartphones at night

    Science.gov (United States)

    Oh, Ji Hye; Yoo, Heeyeon; Park, Hoo Keun; Do, Young Rag

    2015-06-01

    This study proposes representative figures of merit for circadian and vision performance for healthy and efficient use of smartphone displays. The recently developed figures of merit for circadian luminous efficacy of radiation (CER) and circadian illuminance (CIL) related to human health and circadian rhythm were measured to compare three kinds of commercial smartphone displays. The CIL values for social network service (SNS) messenger screens from all three displays were higher than 41.3 biolux (blx) in a dark room at night, and the highest CIL value reached 50.9 blx. These CIL values corresponded to melatonin suppression values (MSVs) of 7.3% and 11.4%, respectively. Moreover, smartphone use in a bright room at night had much higher CIL and MSV values (58.7 ~ 105.2 blx and 15.4 ~ 36.1%, respectively). This study also analyzed the nonvisual and visual optical properties of the three smartphone displays while varying the distance between the screen and eye and controlling the brightness setting. Finally, a method to possibly attenuate the unhealthy effects of smartphone displays was proposed and investigated by decreasing the emitting wavelength of blue LEDs in a smartphone LCD backlight and subsequently reducing the circadian effect of the display.

  12. Blue Light Hazard and Risk Group Classification of 8 W LED Tubes, Replacing Fluorescent Tubes, through Optical Radiation Measurements

    Directory of Open Access Journals (Sweden)

    Francesco Leccese

    2015-09-01

    Full Text Available In this paper, the authors discuss the results of a measurement survey of artificial optical radiation emitted by 8 W LED tubes suitable for the substitution of 18 W fluorescent lamps used for general lighting. For both types of lamps, three different color temperatures were chosen, 3000 K, 4000 K, and 6000 K. These measurements were performed to evaluate the photobiological safety of the sources. The radiance and irradiance values have been measured in a wide range of wavelengths (180–3000 nm. The measurement results obtained for the LED tubes have been compared to those of similar measurements obtained for fluorescent lamps. The analysis has been focused on the range of wavelengths 300–700 nm, the blue light range, which turned out to be defining for the risk groups of the lamps. This classification is a function of the maximum permissible exposure time as indicated in the European Standard EN 62471 on the photobiological safety of lamps and lamp systems.

  13. Structural Insights into the HWE Histidine Kinase Family: The Brucella Blue Light-Activated Histidine Kinase Domain.

    Science.gov (United States)

    Rinaldi, Jimena; Arrar, Mehrnoosh; Sycz, Gabriela; Cerutti, María Laura; Berguer, Paula M; Paris, Gastón; Estrín, Darío Ariel; Martí, Marcelo Adrián; Klinke, Sebastián; Goldbaum, Fernando Alberto

    2016-03-27

    In response to light, as part of a two-component system, the Brucella blue light-activated histidine kinase (LOV-HK) increases its autophosphorylation, modulating the virulence of this microorganism. The Brucella histidine kinase (HK) domain belongs to the HWE family, for which there is no structural information. The HWE family is exclusively present in proteobacteria and usually coupled to a wide diversity of light sensor domains. This work reports the crystal structure of the Brucella HK domain, which presents two different dimeric assemblies in the asymmetric unit: one similar to the already described canonical parallel homodimers (C) and the other, an antiparallel non-canonical (NC) dimer, each with distinct relative subdomain orientations and dimerization interfaces. Contrary to these crystallographic structures and unlike other HKs, in solution, the Brucella HK domain is monomeric and still active, showing an astonishing instability of the dimeric interface. Despite this instability, using cross-linking experiments, we show that the C dimer is the functionally relevant species. Mutational analysis demonstrates that the autophosphorylation activity occurs in cis. The different relative subdomain orientations observed for the NC and C states highlight the large conformational flexibility of the HK domain. Through the analysis of these alternative conformations by means of molecular dynamics simulations, we also propose a catalytic mechanism for Brucella LOV-HK.

  14. Sodium cholate-templated blue light-emitting Ag subnanoclusters: in vivo toxicity and imaging in zebrafish embryos.

    Science.gov (United States)

    Chandirasekar, Shanmugam; Chandrasekaran, Chandramouli; Muthukumarasamyvel, Thangavel; Sudhandiran, Ganapasam; Rajendiran, Nagappan

    2015-01-28

    We report a novel green chemical approach for the synthesis of blue light-emitting and water-soluble Ag subnanoclusters, using sodium cholate (NaC) as a template at a concentration higher than the critical micelle concentration (CMC) at room temperature. However, under photochemical irradiation, small anisotropic and spherically shaped Ag nanoparticles (3-11 nm) were obtained upon changing the concentration of NaC from below to above the CMC. The matrix-assisted laser desorption ionization time-of-flight and electrospray ionization mass spectra showed that the cluster sample was composed of Ag4 and Ag6. The optical properties of the clusters were studied by UV-visible and luminescence spectroscopy. The lifetime of the synthesized fluorescent Ag nanoclusters (AgNCs) was measured using a time-correlated single-photon counting technique. High-resolution transmission electron microscopy was used to assess the size of clusters and nanoparticles. A protocol for transferring nanoclusters to organic solvents is also described. Toxicity and bioimaging studies of NaC templated AgNCs were conducted using developmental stage zebrafish embryos. From the survival and hatching experiment, no significant toxic effect was observed at AgNC concentrations of up to 200 μL/mL, and the NC-stained embryos exhibited blue fluorescence with high intensity for a long period of time, which shows that AgNCs are more stable in living system.

  15. BLUE LIGHT-EMITTING COIL-ROD-COIL BLOCK OLIGOMERS WITH RIGID p-HEXAPHENYL AS CHROMOPHORE

    Institute of Scientific and Technical Information of China (English)

    Jiang-feng Fan; Hai-feng He; Xin-hua Wan; Xiao-fang Chen; Qi-feng Zhou

    2006-01-01

    The synthesis and characterization of coil-rod-coil triblock oligomers, poly(ethylene oxide)-b-p-hexaphenyl-b-poly(ethylene oxide), are described. The number of repeating ethylene oxide units in each flexible block are 3 (EO3-PHP-EO3), 8 (EO8-PHP-EO8), 13 (EO13-PHP-EO13), and 17 (EO17-PHP-EO17), respectively. The structures of these oligomers are confirmed by 1H-NMR, 13C-NMR, EA, and MALDI-TOF mass spectrometry. The introduction of soluble poly(ethylene oxide) coils to the rigid p-hexaphenyl segment significantly improves the solubility of the oligomers, so they can form smooth thin films by spin-coating from their solutions. The oligomers are quite thermally stable and have 1% weight loss temperatures at above 340℃ under nitrogen. They can emit strong blue light in both solution and film state, and have fluorescence quantum yields of about 40% in chloroform. They are expected to have potential applications in optoelectronic devices.

  16. Highly efficient multilayer organic pure blue light emitting diodes with substituted carbazoles compounds in the emitting layer

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, A [Laboratoire de Physique des Lasers (LPL, CNRS), Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Chenais, S [Laboratoire de Physique des Lasers (LPL, CNRS), Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Forget, S [Laboratoire de Physique des Lasers (LPL, CNRS), Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Castex, M-C [Laboratoire de Physique des Lasers (LPL, CNRS), Institut Galilee, Universite Paris 13, 93430 Villetaneuse (France); Ades, D [Biomateriaux et Polymeres de Specialite (BPS/B2OA, CNRS), Institut Galilee, Universite Paris 13, Villetaneuse/Faculte de Medecine Lariboisiere-St Louis, Universite Paris 7, 75010 Paris (France); Siove, A [Biomateriaux et Polymeres de Specialite (BPS/B2OA, CNRS), Institut Galilee, Universite Paris 13, Villetaneuse/Faculte de Medecine Lariboisiere-St Louis, Universite Paris 7, 75010 Paris (France); Denis, C [Laboratoire Cellules et Composants, CEA/LITEN/DSEN, CEA Saclay, 91191 Gif-sur-Yvette (France); Maisse, P [Laboratoire Cellules et Composants, CEA/LITEN/DSEN, CEA Saclay, 91191 Gif-sur-Yvette (France); Geffroy, B [Laboratoire Cellules et Composants, CEA/LITEN/DSEN, CEA Saclay, 91191 Gif-sur-Yvette (France)

    2006-03-07

    Bright blue organic light-emitting diodes (OLEDs) based on 1, 4, 5, 8, N-pentamethylcarbazole (PMC) and on dimer of N-ethylcarbazole (N, N'-diethyl-3, 3'-bicarbazyl) (DEC) as emitting layers or as dopants in a 4, 4'-bis(2, 2'-diphenylvinyl)-1, 1'-biphenyl (DPVBi) matrix are described. Pure blue light with the CIE coordinates (x = 0.153, y = 0.100), electroluminescence efficiency {eta}{sub EL} of 0.4 cd A{sup -1}, external quantum efficiency {eta}{sub ext} of 0.6% and luminance L of 236 cd m{sup -2} (at 60 mA cm{sup -2}) were obtained with PMC as an emitter and the 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenantroline (BCP) as a hole-blocking material in five-layer emitting devices. The highest efficiencies {eta}{sub EL} of 4.7 cd A{sup -1} and {eta}{sub ext} = 3.3% were obtained with a four-layer structure and a DPVBi DEC-doped active layer (CIE coordinates x = 0.158, y = 0.169, {lambda}{sub peak} = 456 nm). The {eta}{sub ext} value is one the highest reported at this wavelength for blue OLEDs and is related to an internal quantum efficiency up to 20%.

  17. Highly efficient multilayer organic pure blue light emitting diodes with substituted carbazoles compounds in the emitting layer

    Science.gov (United States)

    Fischer, A.; Chénais, S.; Forget, S.; Castex, M.-C.; Adès, D.; Siove, A.; Denis, C.; Maisse, P.; Geffroy, B.

    2006-03-01

    Bright blue organic light-emitting diodes (OLEDs) based on 1, 4, 5, 8, N-pentamethylcarbazole (PMC) and on dimer of N-ethylcarbazole (N, N'-diethyl-3, 3'-bicarbazyl) (DEC) as emitting layers or as dopants in a 4, 4'-bis(2, 2'-diphenylvinyl)-1, 1'-biphenyl (DPVBi) matrix are described. Pure blue light with the CIE coordinates (x = 0.153, y = 0.100), electroluminescence efficiency ηEL of 0.4 cd A-1, external quantum efficiency ηext of 0.6% and luminance L of 236 cd m-2 (at 60 mA cm-2) were obtained with PMC as an emitter and the 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenantroline (BCP) as a hole-blocking material in five-layer emitting devices. The highest efficiencies ηEL of 4.7 cd A-1 and ηext = 3.3% were obtained with a four-layer structure and a DPVBi DEC-doped active layer (CIE coordinates x = 0.158, y = 0.169, λpeak = 456 nm). The ηext value is one the highest reported at this wavelength for blue OLEDs and is related to an internal quantum efficiency up to 20%.

  18. Highly efficient multilayer organic pure-blue-light emitting diodes with substituted carbazoles compounds in the emitting layer

    CERN Document Server

    Fischer, A; Chenais, S; Castex, M C; Siove, A; Ades, D; Geffroy, B; Denis, C; Maisse, P; Fischer, Alexis; Forget, Sebastien; Chenais, Sebastien; Castex, Marie-Claude; Siove, Alain; Ades, Dominique; Geffroy, Bernard; Denis, Christine; Maisse, Pascal

    2006-01-01

    Bright blue organic light-emitting diodes (OLEDs) based on 1,4,5,8,N-pentamethylcarbazole (PMC) and on dimer of N-ethylcarbazole (N,N'-diethyl-3,3'-bicarbazyl) (DEC) as emitting layers or as dopants in a 4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl (DPVBi) matrix are described. Pure blue-light with the C.I.E. coordinates x = 0.153 y = 0.100, electroluminescence efficiency \\eta_{EL} of 0.4 cd/A, external quantum efficiency \\eta_{ext.} of 0.6% and luminance L of 236 cd/m2 (at 60 mA/cm2) were obtained with PMC as an emitter and the 2,9-dimethyl-4,7-diphenyl-1,10-phenantroline (BCP) as a hole-blocking material in five-layer emitting devices. The highest efficiencies \\eta_{EL.} of 4.7 cd/A, and \\eta_{ext} = 3.3% were obtained with a four-layer structure and a DPVBi DEC-doped active layer (CIE coordinates x = 0.158, y=0.169, \\lambda_{peak} = 456 nm). The \\eta_{ext.} value is one the highest reported at this wavelength for blue OLEDs and is related to an internal quantum efficiency up to 20%.

  19. Adjunctive dental therapy via tooth plaque reduction and gingivitis treatment by blue light-emitting diodes tooth brushing

    Science.gov (United States)

    Genina, Elina A.; Titorenko, Vladimir A.; Belikov, Andrey V.; Bashkatov, Alexey N.; Tuchin, Valery V.

    2015-12-01

    The efficacy of blue light-emitting toothbrushes (B-LETBs) (405 to 420 nm, power density 2 mW/cm2) for reduction of dental plaques and gingival inflammation has been evaluated. Microbiological study has shown the multifactor therapeutic action of the B-LETBs on oral pathological microflora: in addition to partial mechanical removal of bacteria, photodynamic action suppresses them up to 97.5%. In the pilot clinical studies, subjects with mild to moderate gingivitis have been randomly divided into two groups: a treatment group that used the B-LETBs and a control group that used standard toothbrushes. Indices of plaque, gingival bleeding, and inflammation have been evaluated. A significant improvement of all dental indices in comparison with the baseline (by 59%, 66%, and 82% for plaque, gingival bleeding, and inflammation, respectively) has been found. The treatment group has demonstrated up to 50% improvement relative to the control group. We have proposed the B-LETBs to serve for prevention of gingivitis or as an alternative to conventional antibiotic treatment of this disease due to their effectiveness and the absence of drug side effects and bacterial resistance.

  20. Using electroretinograms and multi-model inference to identify spectral classes of photoreceptors and relative opsin expression levels

    Directory of Open Access Journals (Sweden)

    Nicolas Lessios

    2017-07-01

    Full Text Available Understanding how individual photoreceptor cells factor in the spectral sensitivity of a visual system is essential to explain how they contribute to the visual ecology of the animal in question. Existing methods that model the absorption of visual pigments use templates which correspond closely to data from thin cross-sections of photoreceptor cells. However, few modeling approaches use a single framework to incorporate physical parameters of real photoreceptors, which can be fused, and can form vertical tiers. Akaike’s information criterion (AICc was used here to select absorptance models of multiple classes of photoreceptor cells that maximize information, given visual system spectral sensitivity data obtained using extracellular electroretinograms and structural parameters obtained by histological methods. This framework was first used to select among alternative hypotheses of photoreceptor number. It identified spectral classes from a range of dark-adapted visual systems which have between one and four spectral photoreceptor classes. These were the velvet worm, Principapillatus hitoyensis, the branchiopod water flea, Daphnia magna, normal humans, and humans with enhanced S-cone syndrome, a condition in which S-cone frequency is increased due to mutations in a transcription factor that controls photoreceptor expression. Data from the Asian swallowtail, Papilio xuthus, which has at least five main spectral photoreceptor classes in its compound eyes, were included to illustrate potential effects of model over-simplification on multi-model inference. The multi-model framework was then used with parameters of spectral photoreceptor classes and the structural photoreceptor array kept constant. The goal was to map relative opsin expression to visual pigment concentration. It identified relative opsin expression differences for two populations of the bluefin killifish, Lucania goodei. The modeling approach presented here will be useful in

  1. ApcD is required for state transition but not involved in blue-light induced quenching in the cyanobacterium Anabaena sp. PCC7120

    Institute of Scientific and Technical Information of China (English)

    DONG ChunXia; ZHAO JinDong

    2008-01-01

    Pbycobilisomes (PBS) are able to transfer absorbed energy to photosystem Ⅰ and Ⅱ, and the distribution of light energy between two photosystems is regulated by state transitions. In this study we show that energy transfer from PBS to photosystem Ⅰ (PSI) requires ApcD. Cells were unable to perform state transitions in the absence of ApcD. The apcD mutant grows more slowly in light mainly absorbed by PBS, indicating that ApcD-dependent energy transfer to PSI is required for optimal growth under this condition. The apoD mutant showed normal blue-light induced quenching, suggesting that ApcD is not required for this process and state transitions are independent of blue-light induced quenching. Under nitrogen fixing condition, the growth rates of the wild type and the mutant were the same, indicating that energy transfer from PBS to PSI in heterocysta was not required for nitrogen fixation.

  2. Efficiency droop alleviation in blue light emitting diodes using the InGaN/GaN triangular-shaped quantum well

    Institute of Scientific and Technical Information of China (English)

    Chen Zhao; Hu Chen Wei-Hua; Xiao-Dong; Yang Wei; Liu Lei; Wan Cheng-Hao; Li Lei; He Yong-Fa; Liu Ning-Yang; Wang Lei; Li Din

    2012-01-01

    The InGaN/GaN blue light emitting diode (LED) is numerically investigated using a triangular-shaped quantum well model,which involves analysis on its energy band,carrier concentration,overlap of electron and hole wave functions,radiative recombination rate,and internal quantum efficiency.The simulation results reveal that the InGaN/GaN blue light emitting diode with triangular quantum wells exhibits a higher radiative recombination rate than the conventional light emitting diode with rectangular quantum wells due to the enhanced overlap of electron and hole wave functions (above 90%) under the polarization field.Consequently,the efficiency droop is only 18% in the light emitting diode with triangular-shaped quantum wells,which is three times lower than that in a conventional LED.

  3. Epidermal UV-A absorbance and whole-leaf flavonoid composition in pea respond more to solar blue light than to solar UV radiation.

    Science.gov (United States)

    Siipola, Sari M; Kotilainen, Titta; Sipari, Nina; Morales, Luis O; Lindfors, Anders V; Robson, T Matthew; Aphalo, Pedro J

    2015-05-01

    Plants synthesize phenolic compounds in response to certain environmental signals or stresses. One large group of phenolics, flavonoids, is considered particularly responsive to ultraviolet (UV) radiation. However, here we demonstrate that solar blue light stimulates flavonoid biosynthesis in the absence of UV-A and UV-B radiation. We grew pea plants (Pisum sativum cv. Meteor) outdoors, in Finland during the summer, under five types of filters differing in their spectral transmittance. These filters were used to (1) attenuate UV-B; (2) attenuate UV-B and UV-A radiation signals that extend into the visible region of the solar spectrum. Furthermore, solar blue light instead of solar UV-B radiation can be the main regulator of phenolic compound accumulation in plants that germinate and develop outdoors.

  4. Photophysical study of blue-light excitable ternary Eu(III) complexes and their encapsulation into polystyrene nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Räsänen, Markus, E-mail: mpvras@utu.fi [Department of Chemistry, University of Turku, FIN-20014 Turku (Finland); Takalo, Harri [DHR Finland Oy, Innotrac Diagnostics, Biolinja 12, FIN-20750 Turku (Finland); Soukka, Tero [Department of Biochemistry/Biotechnology, University of Turku, FIN-20014 Turku (Finland); Haapakka, Keijo; Kankare, Jouko [Department of Chemistry, University of Turku, FIN-20014 Turku (Finland)

    2015-04-15

    In this work, 14 ternary Eu(III) complexes were studied by means of spectroscopy. The studied Eu(III) complexes consisted of Lewis bases (4′-(4-diethylaminophenyl)-2,2′:6′,2″-terpyridine (L{sup 8}) or 1,10-phenanthroline (L{sup 9})) and differently substituted β-diketones. The ternary complexes with L{sup 8} show the excitation peak at 405 nm and the quantum yield even 76%. The brightest ternary complex at the 405 nm excitation was Eu(L{sup 3}){sub 3}L{sup 8} while Eu(L{sup 7}){sub 3}L{sup 8} (HL{sup 3}=4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, HL{sup 7}=1-(9-ethyl-9H-carbazol-3-yl)-4,4,5,5,5-pentafluoro-1,3-pentanedione) was found to be the brightest at the ligand-centred excitation maximum. The ternary complexes were studied mainly in toluene as the model environment for the polystyrene nanoparticle cavities. The complexes were successfully loaded into the polystyrene nanoparticles enabling their bioanalytical application in aqueous environment. The encapsulation of the complexes preserved, or even enhanced, their good photophysical features. - Highlights: • Ternary Eu{sup 3+} complexes with some β-diketone and substituted terpyridine were studied. • Ternary complexes with substituted terpyridine showed blue-light excitability. • Ternary complexes were successfully loaded into the polystyrene nanoparticles. • Encapsulation of the complexes preserved their good photophysical features.

  5. Inhibition of Blue Light-Dependent H+ Pumping by Abscisic Acid in Vicia Guard-Cell Protoplasts.

    Science.gov (United States)

    Goh, C. H.; Kinoshita, T.; Oku, T.; Shimazaki, Ki.

    1996-06-01

    Blue-light (BL)-dependent H+ pumping in guard-cell protoplasts (GCPs) from Vicia faba was inhibited by 65% in the presence of abscisic acid (ABA). The inhibition increased with the time after application of ABA and was concentration dependent with a saturating concentration of 1 [mu]M at pH 6.2. The inhibition was nearly independent of the pH of the medium in the range 5.4 to 7.2 when ABA was applied at 10 [mu]M, whereas it was dependent on pH when the ABA concentration was decreased. The protonated form of ABA was saturating at 40 nM in inhibiting BL-dependent H+ pumping under various experimental conditions, whereas the dissociated form at 500 nM had no inhibitory effect on the pumping, suggesting that the protonated form of ABA is the form active in inhibiting the pumping. Fusicoccin (10 [mu]M), an activator of plasma membrane H+-ATPase, induced H+ pumping from GCPs, and the rate of H+ pumping was decreased to 70% by ABA. In contrast, ABA did not inhibit H+ pumping in isolated microsome vesicles from GCPs. These results suggest that the inhibition of BL-dependent H+ pumping by ABA in GCPs may be due to indirect inactivation of plasma membrane H+-ATPase and/or inhibition of the BL-signaling pathway. The pump inhibition by ABA causes membrane depolarization and can be an initial step to induce stomatal closure and reduces the transpirational water loss under drought stress in the daytime.

  6. Photochemical Reactions of the LOV and LOV-Linker Domains of the Blue Light Sensor Protein YtvA.

    Science.gov (United States)

    Choi, Seokwoo; Nakasone, Yusuke; Hellingwerf, Klaas J; Terazima, Masahide

    2016-06-07

    YtvA is a blue light sensor protein composed of an N-terminal LOV (light-oxygen-voltage) domain, a linker helix, and the C-terminal sulfate transporter and anti-σ factor antagonist domain. YtvA is believed to act as a positive regulator for light and salt stress responses by regulating the σB transcription factor. Although its biological function has been studied, the reaction dynamics and molecular mechanism underlying the function are not well understood. To improve our understanding of the signaling mechanism, we studied the reaction of the LOV domain (YLOV, amino acids 26-127), the LOV domain with its N-terminal extension (N-YLOV, amino acids 1-127), the LOV domain with its C-terminal linker helix (YLOV-linker, amino acids 26-147), and the YLOV domain with the N-terminal extension and the C-terminal linker helix (N-YLOV-linker, amino acids 1-147) using the transient grating method. The signals of all constructs showed adduct formation, thermal diffusion, and molecular diffusion. YLOV showed no change in the diffusion coefficient (D), while the other three constructs showed a significant decrease in D within ∼70 μs of photoexcitation. This indicates that conformational changes in both the N- and C-terminal helices of the YLOV domain indeed do occur. The time constant in the YtvA derivatives was much faster than the corresponding dynamics of phototropins. Interestingly, an additional reaction was observed as a volume expansion as well as a slight increase in D only when both helices were included. These findings suggest that although the rearrangement of the N- and C-terminal helices occurs independently on the fast time scale, this change induces an additional conformational change only when both helices are present.

  7. Cystic acne improved by photodynamic therapy with short-contact 5-aminolevulinic acid and sequential combination of intense pulsed light and blue light activation.

    Science.gov (United States)

    Melnick, Stuart

    2005-01-01

    Photodynamic therapy with short-contact 5-aminolevulinic acid (Levulan Kerastick, Dusa Pharmaceuticals, Inc.) and activation by intense pulsed light in an initial treatment and blue light in 3 subsequent treatments has resulted in significant improvement in severity of acne, reduction in the number of lesions, improvement in skin texture, and smoothing of scar edges in an Asian patient with severe (class 4) facial cystic acne and scarring.

  8. A novel strategy for selective gene delivery by using the inhibitory effect of blue light on jetPRIME-mediated transfection.

    Science.gov (United States)

    Dateki, Minori; Imamura, Osamu; Arai, Masaaki; Shimizu, Hidehisa; Takishima, Kunio

    2016-07-01

    Photodynamic control of gene delivery is a new technology with growing applications in gene therapy and basic cell research. Main approaches of light-selective gene delivery rely on the light-dependent enhancement of transfection efficiency. Studies focused on light-stimulated inhibitory regulation of transfection have rarely been reported. Here, we tried to establish a novel procedure of light-dependent inhibition of transfection. Our experiments, conducted with several types of commercial transfection reagents, revealed that jetPRIME-mediated transfection was strongly inhibited by blue light. Although the uptake of reagent-DNA complex was drastically reduced, preliminary exposure of cells or reagent-DNA complex to blue light had no inhibitory effect on the transfection efficiency. The inhibitory effect was wavelength-dependent and mediated by reactive oxygen species. Partial exposure of a culture vessel to blue light resulted in selective gene delivery into cells grown on the unexposed area of the vessel. By using this approach, different types of plasmid DNA were delivered into different areas in the culture vessel. This novel approach to the inhibitory control of transfection provides practical options for research and therapeutics. Biotechnol. Bioeng. 2016;113: 1560-1567. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  9. Essential role of the A'α/Aβ gap in the N-terminal upstream of LOV2 for the blue light signaling from LOV2 to kinase in Arabidopsis photototropin1, a plant blue light receptor.

    Directory of Open Access Journals (Sweden)

    Sachiko Kashojiya

    Full Text Available Phototropin (phot is a blue light (BL receptor in plants and is involved in phototropism, chloroplast movement, stomata opening, etc. A phot molecule has two photo-receptive domains named LOV (Light-Oxygen-Voltage 1 and 2 in its N-terminal region and a serine/threonine kinase (STK in its C-terminal region. STK activity is regulated mainly by LOV2, which has a cyclic photoreaction, including the transient formation of a flavin mononucleotide (FMN-cysteinyl adduct (S390. One of the key events for the propagation of the BL signal from LOV2 to STK is conformational changes in a Jα-helix residing downstream of the LOV2 C-terminus. In contrast, we focused on the role of the A'α-helix, which is located upstream of the LOV2 N-terminus and interacts with the Jα-helix. Using LOV2-STK polypeptides from Arabidopsis thaliana phot1, we found that truncation of the A'α-helix and amino acid substitutions at Glu474 and Lys475 in the gap between the A'α and the Aβ strand of LOV2 (A'α/Aβ gap to Ala impaired the BL-induced activation of the STK, although they did not affect S390 formation. Trypsin digested the LOV2-STK at Lys603 and Lys475 in a light-dependent manner indicating BL-induced structural changes in both the Jα-helix and the gap. The digestion at Lys603 is faster than at Lys475. These BL-induced structural changes were observed with the Glu474Ala and the Lys475Ala substitutes, indicating that the BL signal reached the Jα-helix as well as the A'α/Aβ gap but could not activate STK. The amino acid residues, Glu474 and Lys475, in the gap are conserved among the phots of higher plants and may act as a joint to connect the structural changes in the Jα-helix with the activation of STK.

  10. Effects of 630 nm Red and 460 nm Blue Light Emitting Diode Irradiation on Healing of the Skin Wound in Japanese Big-ear White Rabbit.

    Science.gov (United States)

    Li, Yanhong; Zhang, Jigang; Xu, Yanfeng; Han, Yunlin; Jiang, Binbin; Huang, Lan; Zhu, Hua; Xu, Yuhuan; Yang, Weiling; Qin, Chuan

    2017-06-20

    Objective To observe the effects of 630 nm red light and 460 nm blue light emitting diode irradiation on the healing of skin wounds in Japanese big-ear white rabbits. Methods The skin wound model was established with 8 Japanese big-ear white rabbits. Three parts of vulnus in each rabbit were used:two parts of vulnus were irradiated vertically by red and blue LED light,respectively(15 min/time),and the distance between lights and wounds was 15 cm;the 3(rd) part of the wound was used as a control. On the 21(st) day of the wounds exposure to light,the number of healing wounds and the percentage of healing area were recorded and the treatment effect of these two light sources was compared. HE staining was used to analyze the newborn tissue structure. Masson staining was used to observe the proliferation of skin collagen fibers. Immuohistochemical staining was used to analyze fibroblast growth factor(FGF),epidermal growth factor(EGF),endothelial growth factor(CD31),proliferating cell nuclear antigen(Ki-67),and inflammatory cytokines(CD68)infiltration in the skin. Results The healing rate in the red light,blue light,and control groups was 50.0%(4/8),25.0%(2/8),and 12.5%(1/8),respectively. Since the 12(th) day after modeling,the healing area percentage in the red light group was significantly higher than those in the blue light and control groups(Plight group was(2.95±0.34)mm,which was significantly higher than that in control group [(2.52±0.42)mm;F=3.182,P=0.016)]. The average optical density of collagen fibers was 0.15±0.03 in red light group,which was significantly higher than that of the blue light group(0.09±0.01;F=7.316,P=0.012)and control(0.07±0.01;F=7.316,P=0.003). The results of immunohistochemistry showed the expression levels of EGF,FGF,CD31 antigen,and Ki-67 in the red light group were significantly higher than those in the blue light and control groups,whereas the CD68 expression was significantly lower(Plight irradiation can promote the healing of skin

  11. Photocontrol of the Functional Coupling between Photosynthesis and Stomatal Conductance in the Intact Leaf : Blue Light and Par-Dependent Photosystems in Guard Cells.

    Science.gov (United States)

    Zeiger, E; Field, C

    1982-08-01

    The photocontrol of the functional coupling between photosynthesis and stomatal conductance in the leaf was investigated in gas exchange experiments using monochromatic light provided by lasers. Net photosynthesis and stomatal conductance were measured in attached leaves of Malva parviflora L. as a function of photon irradiance at 457.9 and 640.0 nanometers.Photosynthetic rates and quantum yields of photosynthesis were higher under red light than under blue, on an absorbed or incident basis.Stomatal conductance was higher under blue than under red light at all intensities. Based on a calculated apparent photon efficiency of conductance, blue and red light had similar effects on conductance at intensities higher than 0.02 millimoles per square meter per second, but blue light was several-fold more efficient at very low photon irradiances. Red light had no effect on conductance at photon irradiances below 0.02 millimoles per square meter per second. These observations support the hypothesis that stomatal conductance is modulated by two photosystems: a blue light-dependent one, driving stomatal opening at low light intensities and a photosynthetically active radiation (PAR)-dependent one operating at higher irradiances.When low intensity blue light was used to illuminate a leaf already irradiated with high intensity, 640 nanometers light, the leaf exhibited substantial increases in stomatal conductance. Net photosynthesis changed only slightly. Additional far-red light increased net photosynthesis without affecting stomatal conductance. These observations indicate that under conditions where the PAR-dependent system is driven by high intensity red light, the blue light-dependent system has an additive effect on stomatal conductance.The wavelength dependence of photosynthesis and stomatal conductance demonstrates that these processes are not obligatorily coupled and can be controlled by light, independent of prevailing levels of intercellular CO(2). The blue light

  12. Role of spectraplakin in Drosophila photoreceptor morphogenesis.

    Directory of Open Access Journals (Sweden)

    Uyen Ngoc Mui

    Full Text Available BACKGROUND: Crumbs (Crb, a cell polarity gene, has been shown to provide a positional cue for the apical membrane domain and adherens junction during Drosophila photoreceptor morphogenesis. It has recently been found that stable microtubules in developing Drosophila photoreceptors were linked to Crb localization. Coordinated interactions between microtubule and actin cytoskeletons are involved in many polarized cellular processes. Since Spectraplakin is able to bind both microtubule and actin cytoskeletons, the role of Spectraplakin was analyzed in the regulations of apical Crb domain in developing Drosophila photoreceptors. METHODOLOGY/PRINCIPAL FINDINGS: The localization pattern of Spectraplakin in developing pupal photoreceptors showed a unique intracellular distribution. Spectraplakin localized at rhabdomere terminal web which is at the basal side of the apical Crb or rhabdomere, and in between the adherens junctions. The spectraplakin mutant photoreceptors showed dramatic mislocalizations of Crb, adherens junctions, and the stable microtubules. This role of Spectraplakin in Crb and adherens junction regulation was further supported by spectraplakin's gain-of-function phenotype. Spectraplakin overexpression in photoreceptors caused a cell polarity defect including dramatic mislocalization of Crb, adherens junctions and the stable microtubules in the developing photoreceptors. Furthermore, a strong genetic interaction between spectraplakin and crb was found using a genetic modifier test. CONCLUSIONS/SIGNIFICANCE: In summary, we found a unique localization of Spectraplakin in photoreceptors, and identified the role of spectraplakin in the regulation of the apical Crb domain and adherens junctions through genetic mutational analysis. Our data suggest that Spectraplakin, an actin-microtubule cross-linker, is essential in the apical and adherens junction controls during the photoreceptors morphogenesis.

  13. Arap1 Deficiency Causes Photoreceptor Degeneration in Mice

    Science.gov (United States)

    Moshiri, Ala; Humpal, Devin; Leonard, Brian C.; Imai, Denise M.; Tham, Addy; Bower, Lynette; Clary, Dave; Glaser, Thomas M.; Lloyd, K. C. Kent; Murphy, Christopher J.

    2017-01-01

    Purpose Small guanosine triphosphatase (GTPase) ADP-ribosylation factors (Arfs) regulate membrane traffic and actin reorganization under the control of GTPase-activating proteins (GAPs). Arap1 is an Arf-directed GAP that inhibits the trafficking of epidermal growth factor receptor (EGFR) to the early endosome, but the diversity of its functions is incompletely understood. The aim of this study was to determine the role of Arap1 in the mammalian retina. Methods Genetically engineered Arap1 knockout mice were screened for ocular abnormalities in the National Institutes of Health Knockout Mouse Production and Phenotyping (KOMP2) Project. Arap1 knockout and wild-type eyes were imaged using optical coherence tomography and fundus photography, and analyzed by immunohistochemistry. Results Arap1−/− mice develop a normal appearing retina, but undergo photoreceptor degeneration starting at 4 weeks postnatal age. The fundus appearance of mutants is notable for pigmentary changes, optic nerve pallor, vascular attenuation, and outer retinal thinning, reminiscent of retinitis pigmentosa in humans. Immunohistochemical studies suggest the cell death is predominantly in the outer nuclear layer. Functional evaluation of the retina by electroretinography reveals amplitudes are reduced. Arap1 is detected most notably in Müller glia, and not in photoreceptors, implicating a role for Müller glia in photoreceptor survival. Conclusions Arap1 is necessary for normal photoreceptor survival in mice, and may be a novel gene relevant to human retinal degenerative processes, although its mechanism is unknown. Further studies in this mouse model of retinal degeneration will give insights into the cellular functions and signaling pathways in which Arap1 participates. PMID:28324111

  14. Retinoic acid regulates the expression of photoreceptor transcription factor NRL.

    Science.gov (United States)

    Khanna, Hemant; Akimoto, Masayuki; Siffroi-Fernandez, Sandrine; Friedman, James S; Hicks, David; Swaroop, Anand

    2006-09-15

    NRL (neural retina leucine zipper) is a key basic motif-leucine zipper (bZIP) transcription factor, which orchestrates rod photoreceptor differentiation by activating the expression of rod-specific genes. The deletion of Nrl in mice results in functional cones that are derived from rod precursors. However, signaling pathways modulating the expression or activity of NRL have not been elucidated. Here, we show that retinoic acid (RA), a diffusible factor implicated in rod development, activates the expression of NRL in serum-deprived Y79 human retinoblastoma cells and in primary cultures of rat and porcine photoreceptors. The effect of RA is mimicked by TTNPB, a RA receptor agonist, and requires new protein synthesis. DNaseI footprinting and electrophoretic mobility shift assays (EMSA) using bovine retinal nuclear extract demonstrate that RA response elements (RAREs) identified within the Nrl promoter bind to RA receptors. Furthermore, in transiently transfected Y79 and HEK293 cells the activity of Nrl-promoter driving a luciferase reporter gene is induced by RA, and this activation is mediated by RAREs. Our data suggest that signaling by RA via RA receptors regulates the expression of NRL, providing a framework for delineating early steps in photoreceptor cell fate determination.

  15. Leaf Morphology, Photosynthetic Performance, Chlorophyll Fluorescence, Stomatal Development of Lettuce (Lactuca sativa L.) Exposed to Different Ratios of Red Light to Blue Light.

    Science.gov (United States)

    Wang, Jun; Lu, Wei; Tong, Yuxin; Yang, Qichang

    2016-01-01

    Red and blue light are both vital factors for plant growth and development. We examined how different ratios of red light to blue light (R/B) provided by light-emitting diodes affected photosynthetic performance by investigating parameters related to photosynthesis, including leaf morphology, photosynthetic rate, chlorophyll fluorescence, stomatal development, light response curve, and nitrogen content. In this study, lettuce plants (Lactuca sativa L.) were exposed to 200 μmol⋅m(-2)⋅s(-1) irradiance for a 16 h⋅d(-1) photoperiod under the following six treatments: monochromatic red light (R), monochromatic blue light (B) and the mixture of R and B with different R/B ratios of 12, 8, 4, and 1. Leaf photosynthetic capacity (A max) and photosynthetic rate (P n) increased with decreasing R/B ratio until 1, associated with increased stomatal conductance, along with significant increase in stomatal density and slight decrease in stomatal size. P n and A max under B treatment had 7.6 and 11.8% reduction in comparison with those under R/B = 1 treatment, respectively. The effective quantum yield of PSII and the efficiency of excitation captured by open PSII center were also significantly lower under B treatment than those under the other treatments. However, shoot dry weight increased with increasing R/B ratio with the greatest value under R/B = 12 treatment. The increase of shoot dry weight was mainly caused by increasing leaf area and leaf number, but no significant difference was observed between R and R/B = 12 treatments. Based on the above results, we conclude that quantitative B could promote photosynthetic performance or growth by stimulating morphological and physiological responses, yet there was no positive correlation between P n and shoot dry weight accumulation.

  16. Chemical-Induced Inhibition of Blue Light-Mediated Seedling Development Caused by Disruption of Upstream Signal Transduction Involving Cryptochromes in Arabidopsis thaliana.

    Science.gov (United States)

    Ong, Wen-Dee; Okubo-Kurihara, Emiko; Kurihara, Yukio; Shimada, Setsuko; Makita, Yuko; Kawashima, Mika; Honda, Kaori; Kondoh, Yasumitsu; Watanabe, Nobumoto; Osada, Hiroyuki; Cutler, Sean R; Sudesh, Kumar; Matsui, Minami

    2017-01-01

    Plants have a remarkable ability to perceive and respond to various wavelengths of light and initiate regulation of different cascades of light signaling and molecular components. While the perception of red light and the mechanisms of its signaling involving phytochromes are largely known, knowledge of the mechanisms of blue light signaling is still limited. Chemical genetics involves the use of diverse small active or synthetic molecules to evaluate biological processes. By combining chemicals and analyzing the effects they have on plant morphology, we identified a chemical, 3-bromo-7-nitroindazole (3B7N), that promotes hypocotyl elongation of wild-type Arabidopsis only under continuous blue light. Further evaluation with loss-of-function mutants confirmed that 3B7N inhibits photomorphogenesis through cryptochrome-mediated light signaling. Microarray analysis demonstrated that the effect of 3B7N treatment on gene expression in cry1cry2 is considerably smaller than that in the wild type, indicating that 3B7N specifically interrupts cryptochrome function in the control of seedling development in a light-dependent manner. We demonstrated that 3B7N directly binds to CRY1 protein using an in vitro binding assay. These results suggest that 3B7N is a novel chemical that directly inhibits plant cryptochrome function by physical binding. The application of 3B7N can be used on other plants to study further the blue light mechanism and the genetic control of cryptochromes in the growth and development of plant species. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  17. 红蓝光照射治疗痤疮110例%Red Light and Blue Light Therapy in Treating Patients with Ache: 110 Cases

    Institute of Scientific and Technical Information of China (English)

    邵燕磊; 王蕾

    2012-01-01

    Objective To investigate the clinical efficacy and safety of the red light and blue light therapy on 110 cases of acne patients. Methods Subjects were treated by the red light and blue light therapy alternatively with a total of eight serial biweekly treatment sessions. They were assessed and compared with the reduced rates of acne lesions in patients before and after treatment. Results The total effective rate was 83.09%. The average reduced rates of the non-inflammatory lesions and inflammatory lesions were 52.36% and 69.47% respectively (P<0.05). After three months follow-up, the total effective rate had no significant statistical difference compare to the end of treatment sessions. Conclusion The treatment of acne patients with the red light and blue light is effective in acne. And it has low recurrence rate and fewer side effects.%目的 观察红蓝光照射治疗痤疮的临床疗效和安全性.方法 联合红蓝光治疗110例痤疮患者,每周2次,共8次,计数患者炎性病损及非炎性病损及皮损总数来比较改善率.结果 治疗结束时有效率为83.09%;非炎性皮损及炎性皮损平均改善率分别为52.36%和69.47%,P<0.05;随访3个月,有效率与治疗结束时比较差异无统计学意义.结论 红蓝光治疗痤疮疗效显著、复发率低、不良反应少.

  18. Cryptochrome 1 in Retinal Cone Photoreceptors Suggests a Novel Functional Role in Mammals.

    Science.gov (United States)

    Nießner, Christine; Denzau, Susanne; Malkemper, Erich Pascal; Gross, Julia Christina; Burda, Hynek; Winklhofer, Michael; Peichl, Leo

    2016-02-22

    Cryptochromes are a ubiquitous group of blue-light absorbing flavoproteins that in the mammalian retina have an important role in the circadian clock. In birds, cryptochrome 1a (Cry1a), localized in the UV/violet-sensitive S1 cone photoreceptors, is proposed to be the retinal receptor molecule of the light-dependent magnetic compass. The retinal localization of mammalian Cry1, homologue to avian Cry1a, is unknown, and it is open whether mammalian Cry1 is also involved in magnetic field sensing. To constrain the possible role of retinal Cry1, we immunohistochemically analysed 90 mammalian species across 48 families in 16 orders, using an antiserum against the Cry1 C-terminus that in birds labels only the photo-activated conformation. In the Carnivora families Canidae, Mustelidae and Ursidae, and in some Primates, Cry1 was consistently labeled in the outer segment of the shortwave-sensitive S1 cones. This finding would be compatible with a magnetoreceptive function of Cry1 in these taxa. In all other taxa, Cry1 was not detected by the antiserum that likely also in mammals labels the photo-activated conformation, although Western blots showed Cry1 in mouse retinal cell nuclei. We speculate that in the mouse and the other negative-tested mammals Cry1 is involved in circadian functions as a non-light-responsive protein.

  19. The dark recovery rate in the photocycle of the bacterial photoreceptor YtvA is affected by the cellular environment and by hydration.

    Directory of Open Access Journals (Sweden)

    Francesca Pennacchietti

    Full Text Available We report thermal recovery kinetics of the lit state into the parental dark state, measured for the blue light-sensing photoreceptor YtvA inside overexpressing E. coli and B. subtilis bacterial cells, performed for the wild type and several mutated proteins. Recovery was followed as a recovery of the fluorescence, as this property is only found for the parental but not for the photochemically generated lit state. When cells were deposited onto a microscope glass plate, the observed thermal recovery rate in the photocycle was found ca. ten times faster in comparison to purified YtvA in solution. When the E. coli or B. subtilis colonies were soaked in an isotonic buffer, the dark relaxation became again much slower and was very similar to that observed for YtvA in solution. The observed effects show that rate constants can be tuned by the cellular environment through factors such as hydration.

  20. Optical properties of photoreceptor and retinal pigment epithelium cells investigated with adaptive optics optical coherence tomography

    Science.gov (United States)

    Liu, Zhuolin

    Human vision starts when photoreceptors collect and respond to light. Photoreceptors do not function in isolation though, but share close interdependence with neighboring photoreceptors and underlying retinal pigment epithelium (RPE) cells. These cellular interactions are essential for normal function of the photoreceptor-RPE complex, but methods to assess these in the living human eye are limited. One approach that has gained increased promise is high-resolution retinal imaging that has undergone tremendous technological advances over the last two decades to probe the living retina at the cellular level. Pivotal in these advances has been adaptive optics (AO) and optical coherence tomography (OCT) that together allow unprecedented spatial resolution of retinal structures in all three dimensions. Using these high-resolution systems, cone photoreceptor are now routinely imaged in healthy and diseased retina enabling fundamental structural properties of cones to be studied such as cell spacing, packing arrangement, and alignment. Other important cell properties, however, have remained elusive to investigation as even better imaging performance is required and thus has resulted in an incomplete understanding of how cells in the photoreceptor-RPE complex interact with light. To address this technical bottleneck, we expanded the imaging capability of AO-OCT to detect and quantify more accurately and completely the optical properties of cone photoreceptor and RPE cells at the cellular level in the living human retina. The first objective of this thesis was development of a new AO-OCT method that is more precise and sensitive, thus enabling a more detailed view of the 3D optical signature of the photoreceptor-RPE complex than was previously possible (Chapter 2). Using this new system, the second objective was quantifying the waveguide properties of individual cone photoreceptor inner and outer segments across the macula (Chapter 3). The third objective extended the AO

  1. Roles for blue light, jasmonate and nitric oxide in the regulation of dormancy and germination in wheat grain (Triticum aestivum L.).

    Science.gov (United States)

    Jacobsen, John V; Barrero, Jose M; Hughes, Trijntje; Julkowska, Magdalena; Taylor, Jennifer M; Xu, Qian; Gubler, Frank

    2013-07-01

    Abscisic acid (ABA) plays a central role in seed dormancy and transcriptional regulation of genes coding for ABA biosynthetic and degradation enzymes is responsible for control of ABA content. However, little is known about signalling both before and after ABA regulation, in particular, how environmental signals are perceived and transduced. We are interested in these processes in cereal grains, particularly in relation to the development of strategies for controlling pre-harvest sprouting in barley and wheat. Our previous studies have indicated possible components of dormancy control and here we present evidence that blue light, nitric oxide (NO) and jasmonate are major controlling elements in wheat grain. Using microarray and pharmacological studies, we have found that blue light inhibits germination in dormant grain and that methyl jasmonate (MJ) and NO counteract this effect by reducing dormancy. We also present evidence that NO and jasmonate play roles in dormancy control in vivo. ABA was reduced by MJ and this was accompanied by reduced levels of expression of TaNCED1 and increased expression of TaABA8'OH-1 compared with dormant grain. Similar changes were caused by after-ripening. Analysis of global gene expression showed that although jasmonate and after-ripening caused important changes in gene expression, the changes were very different. While breaking dormancy, MJ had only a small number of target genes including gene(s) encoding beta-glucosidase. Our evidence indicates that NO and MJ act interdependently in controlling reduction of ABA and thus the demise of dormancy.

  2. Bestrophinopathy: An RPE-photoreceptor interface disease.

    Science.gov (United States)

    Guziewicz, Karina E; Sinha, Divya; Gómez, Néstor M; Zorych, Kathryn; Dutrow, Emily V; Dhingra, Anuradha; Mullins, Robert F; Stone, Edwin M; Gamm, David M; Boesze-Battaglia, Kathleen; Aguirre, Gustavo D

    2017-01-19

    Bestrophinopathies, one of the most common forms of inherited macular degenerations, are caused by mutations in the BEST1 gene expressed in the retinal pigment epithelium (RPE). Both human and canine BEST1-linked maculopathies are characterized by abnormal accumulation of autofluorescent material within RPE cells and bilateral macular or multifocal lesions; however, the specific mechanism leading to the formation of these lesions remains unclear. We now provide an overview of the current state of knowledge on the molecular pathology of bestrophinopathies, and explore factors promoting formation of RPE-neuroretinal separations, using the first spontaneous animal model of BEST1-associated retinopathies, canine Best (cBest). Here, we characterize the nature of the autofluorescent RPE cell inclusions and report matching spectral signatures of RPE-associated fluorophores between human and canine retinae, indicating an analogous composition of endogenous RPE deposits in Best Vitelliform Macular Dystrophy (BVMD) patients and its canine disease model. This study also exposes a range of biochemical and structural abnormalities at the RPE-photoreceptor interface related to the impaired cone-associated microvillar ensheathment and compromised insoluble interphotoreceptor matrix (IPM), the major pathological culprits responsible for weakening of the RPE-neuroretina interactions, and consequently, formation of vitelliform lesions. These salient alterations detected at the RPE apical domain in cBest as well as in BVMD- and ARB-hiPSC-RPE model systems provide novel insights into the pathological mechanism of BEST1-linked disorders that will allow for development of critical outcome measures guiding therapeutic strategies for bestrophinopathies.

  3. Hydrogen bond switching among flavin and amino acid side chains in the BLUF photoreceptor observed by ultrafast infrared spectroscopy.

    Science.gov (United States)

    Bonetti, Cosimo; Mathes, Tilo; van Stokkum, Ivo H M; Mullen, Katharine M; Groot, Marie-Louise; van Grondelle, Rienk; Hegemann, Peter; Kennis, John T M

    2008-11-15

    BLUF domains constitute a recently discovered class of photoreceptor proteins found in bacteria and eukaryotic algae. BLUF domains are blue-light sensitive through a FAD cofactor that is involved in an extensive hydrogen-bond network with nearby amino acid side chains, including a highly conserved tyrosine and glutamine. The participation of particular amino acid side chains in the ultrafast hydrogen-bond switching reaction with FAD that underlies photoactivation of BLUF domains is assessed by means of ultrafast infrared spectroscopy. Blue-light absorption by FAD results in formation of FAD(*-) and a bleach of the tyrosine ring vibrational mode on a picosecond timescale, showing that electron transfer from tyrosine to FAD constitutes the primary photochemistry. This interpretation is supported by the absence of a kinetic isotope effect on the fluorescence decay on H/D exchange. Subsequent protonation of FAD(*-) to result in FADH(*) on a picosecond timescale is evidenced by the appearance of a N-H bending mode at the FAD N5 protonation site and of a FADH(*) C=N stretch marker mode, with tyrosine as the likely proton donor. FADH(*) is reoxidized in 67 ps (180 ps in D(2)O) to result in a long-lived hydrogen-bond switched network around FAD. This hydrogen-bond switch shows infrared signatures from the C-OH stretch of tyrosine and the FAD C4=O and C=N stretches, which indicate increased hydrogen-bond strength at all these sites. The results support a previously hypothesized rotation of glutamine by approximately 180 degrees through a light-driven radical-pair mechanism as the determinant of the hydrogen-bond switch.

  4. Photoreceptor Mediated Plant Growth Responses: Implications for Photoreceptor Engineering toward Improved Performance in Crops

    Directory of Open Access Journals (Sweden)

    Ophilia I. L. Mawphlang

    2017-07-01

    Full Text Available Rising temperatures during growing seasons coupled with altered precipitation rates presents a challenging task of improving crop productivity for overcoming such altered weather patterns and cater to a growing population. Light is a critical environmental factor that exerts a powerful influence on plant growth and development ranging from seed germination to flowering and fruiting. Higher plants utilize a suite of complex photoreceptor proteins to perceive surrounding red/far-red (phytochromes, blue/UV-A (cryptochromes, phototropins, ZTL/FKF1/LKP2, and UV-B light (UVR8. While genomic studies have also shown that light induces extensive reprogramming of gene expression patterns in plants, molecular genetic studies have shown that manipulation of one or more photoreceptors can result in modification of agronomically beneficial traits. Such information can assist researchers to engineer photoreceptors via genome editing technologies to alter expression or even sensitivity thresholds of native photoreceptors for targeting aspects of plant growth that can confer superior agronomic value to the engineered crops. Here we summarize the agronomically important plant growth processes influenced by photoreceptors in crop species, alongwith the functional interactions between different photoreceptors and phytohormones in regulating these responses. We also discuss the potential utility of synthetic biology approaches in photobiology for improving agronomically beneficial traits of crop plants by engineering designer photoreceptors.

  5. Photoreceptor cell dysplasia in two Tippler pigeons.

    Science.gov (United States)

    Moore, P A; Munnell, J F; Martin, C L; Prasse, K W; Carmichael, K P

    2004-01-01

    Two 12-week-old Tippler pigeons were evaluated for ocular abnormalities associated with congenital blindness. The pigeons were emaciated and blind. Biomicroscopy and direct and indirect ophthalmoscopy findings of the Tippler pigeons were normal with the exception of partially dilated pupils at rest. Scotopic (blue stimuli) and photopic monocular electroretinograms were extinguished in the blind Tippler pigeons. Histological and electron microscopy studies revealed reduced numbers of rods and cones, and an absence of the double cone complex. The photoreceptor cells' outer segments were absent, and the inner segments were short and broad. The number of cell nuclei in the outer and inner nuclear layers was decreased, and the internal and external plexiform layers were reduced in width. Photoreceptor cell endfeet with developing synaptic ribbons were present in the external plexiform layer. Inflammatory cell and subretinal debris was not seen. The electroretinographic, histopathological, and ultrastructural findings of the blind Tippler pigeons support the diagnosis of a photoreceptor cell dysplasia.

  6. Ciliopathy-associated IQCB1/NPHP5 protein is required for mouse photoreceptor outer segment formation.

    Science.gov (United States)

    Ronquillo, Cecinio C; Hanke-Gogokhia, Christin; Revelo, Monica P; Frederick, Jeanne M; Jiang, Li; Baehr, Wolfgang

    2016-10-01

    Null mutations in the human IQCB1/NPHP5 (nephrocystin-5) gene that encodes NPHP5 are the most frequent cause of Senior-Løken syndrome, a ciliopathy that is characterized by Leber congenital amaurosis and nephronophthisis. We generated germline Nphp5-knockout mice by placing a β-Geo gene trap in intron 4, thereby truncating NPHP5 at Leu87 and removing all known functional domains. At eye opening, Nphp5(-/-) mice exhibited absence of scotopic and photopic electroretinogram responses, a phenotype that resembles Leber congenital amaurosis. Outer segment transmembrane protein accumulation in Nphp5(-/-) endoplasmic reticulum was evident as early as postnatal day (P)6. EGFP-CETN2, a centrosome and transition zone marker, identified basal bodies in Nphp5(-/-) photoreceptors, but without fully developed transition zones. Ultrastructure of P6 and 10 Nphp5(-/-) photoreceptors revealed aberrant transition zones of reduced diameter. Nphp5(-/-) photoreceptor degeneration was complete at 1 mo of age but was delayed significantly in Nphp5(-/-);Nrl(-/-) (cone only) retina. Nphp5(-/-) mouse embryonic fibroblast developed normal cilia, and Nphp5(-/-) kidney histology at 1 yr of age showed no significant pathology. Results establish that nephrocystin-5 is essential for photoreceptor outer segment formation but is dispensable for kidney and mouse embryonic fibroblast ciliary formation.-Ronquillo, C. C., Hanke-Gogokhia, C., Revelo, M. P., Frederick, J. M., Jiang, L., Baehr, W. Ciliopathy-associated IQCB1/NPHP5 protein is required for mouse photoreceptor outer segment formation. © FASEB.

  7. Use of Hydrogen as a Novel Therapeutic Strategy Against Photoreceptor Degeneration in Retinitis Pigmentosa Patients.

    Science.gov (United States)

    Tao, Ye; Geng, Lei; Wang, Liqiang; Xu, Weiwei; Qin, Limin; Peng, Guanghua; Huang, Yi Fei; Yang, Ji xue

    2016-03-08

    Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal dystrophies characterized by progressive photoreceptor apoptosis. Reactive oxygen species (ROS) have been recognized as critical initiators of the photoreceptor apoptosis in RP. Photoreceptor survival in RP mutants will not only require the inhibition of effectors of apoptotic machinery, but also the elimination of the initiating upstream signals, such as ROS. These cytotoxic ROS should be neutralized by the antioxidant defense system, otherwise they would interact with the macromolecules essential for photoreceptor survival. Hydrogen is a promising gaseous agent that has come to the forefront of therapeutic research over the last few years. It has been verified that hydrogen is capable of neutralizing the cytotoxic ROS selectively, rectifying abnormities in the apoptotic cascades, and attenuating the related inflammatory response. Hydrogen is so mild that it does not disturb the metabolic oxidation-reduction reactions or disrupt the physiologic ROS involved in cell signaling. Based on these findings, we hypothesize that hydrogen might be an effective therapeutic agent to slow or prevent photoreceptor degeneration in RP retinas. It is a logical step to test hydrogen for therapeutic use in multiple RP animal models, and ultimately in human RP patients.

  8. The Histopathological Investigation of Red and Blue Light Emitting Diode on Treating Skin Wounds in Japanese Big-Ear White Rabbit.

    Directory of Open Access Journals (Sweden)

    Yanhong Li

    Full Text Available The biological effects of different wavelengths of light emitting diode (LED light tend to vary from each other. Research into use of photobiomodulation for treatment of skin wounds and the underlying mechanisms has been largely lacking. We explored the histopathological basis of the therapeutic effect of photobiomodulation and the relation between duration of exposure and photobiomodulation effect of different wavelengths of LED in a Japanese big-ear white rabbit skin-wound model. Skin wound model was established in 16 rabbits (three wounds per rabbit: one served as control, the other two wounds were irradiated by red and blue LED lights, respectively. Rabbits were then divided into 2 equal groups based on the duration of exposure to LED lights (15 and 30 min/exposure. The number of wounds that showed healing and the percentage of healed wound area were recorded. Histopathological examination and skin expression levels of fibroblast growth factor (FGF, epidermal growth factor (EGF, endothelial marker (CD31, proliferating cell nuclear antigen (Ki67 and macrophagocyte (CD68 infiltration, and the proliferation of skin collagen fibers was assessed. On days 16 and 17 of irradiation, the healing rates in red (15 min and 30 min and blue (15 min and 30 min groups were 50%, 37.5%, 25% and 37.5%, respectively, while the healing rate in the control group was 12.5%. The percentage healed area in the red light groups was significantly higher than those in other groups. Collagen fiber and skin thickness were significantly increased in both red light groups; expression of EGF, FGF, CD31 and Ki67 in the red light groups was significantly higher than those in other groups; the expression of FGF in red (30 min group was not significantly different from that in the blue light and control groups. The effect of blue light on wound healing was poorer than that of red light. Red light appeared to hasten wound healing by promoting fibrous tissue, epidermal and

  9. Estimating photoreceptor excitations from spectral outputs of a personal light exposure measurement device.

    Science.gov (United States)

    Cao, Dingcai; Barrionuevo, Pablo A

    2015-03-01

    The intrinsic circadian clock requires photoentrainment to synchronize the 24-hour solar day. Therefore, light stimulation is an important component of chronobiological research. Currently, the chronobiological research field overwhelmingly uses photopic illuminance that is based on the luminous efficiency function, V(λ), to quantify light levels. However, recent discovery of intrinsically photosensitive retinal ganglion cells (ipRGCs), which are activated by self-contained melanopsin photopigment and also by inputs from rods and cones, makes light specification using a one-dimensional unit inadequate. Since the current understanding of how different photoreceptor inputs contribute to the circadian system through ipRGCs is limited, it is recommended to specify light in terms of the excitations of five photoreceptors (S-, M-, L-cones, rods and ipRGCs; Lucas et al., 2014). In the current study, we assessed whether the spectral outputs from a commercially available spectral watch (i.e. Actiwatch Spectrum) could be used to estimate photoreceptor excitations. Based on the color sensor spectral sensitivity functions from a previously published work, as well as from our measurements, we computed spectral outputs in the long-wavelength range (R), middle-wavelength range (G), short-wavelength range (B) and broadband range (W) under 52 CIE illuminants (25 daylight illuminants, 27 fluorescent lights). We also computed the photoreceptor excitations for each illuminant using human photoreceptor spectral sensitivity functions. Linear regression analyses indicated that the Actiwatch spectral outputs could predict photoreceptor excitations reliably, under the assumption of linear responses of the Actiwatch color sensors. In addition, R, G, B outputs could classify illuminant types (fluorescent versus daylight illuminants) satisfactorily. However, the assessment of actual Actiwatch recording under several testing light sources showed that the spectral outputs were subject to

  10. Changes in cAMP and cGMP concentration birefringent fibrils and contractile activity accompanying UV and blue light photoavoidance in plasmodia of an albino strain of Physarum polycephalum

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Tetsuo; Mori Yoshihito; Nakagaki, Toshiyuki; Kobatake, Yonosuke

    1988-02-01

    Photoavoidance by plasmodia of an albino strain of Physarum polycephalum was studied. When the organism was irradiated locally, the protoplasm moved away from the irradiated region. The action spectrum for this avoidance showed three peaks at about 260, 370 and 460 nm. The organism was about one hundred times as sensitive to far UV as to near UV and blue light, and high intensity far-UV caused the gelation of the protoplasm. Irradiation with UV or blue light increased the mean level or the amplitude of oscillation in intracellular cAMP and cGMP concentrations. Upon UV irradiation, birefringent fibrils, presumably microfilaments of F-actin, became thick and numerous, and the plasmodial strand generated a strong tensile force. It is postulated that UV or blue light brings about an increased concentration of cyclic nucleotides which leads to an enhanced local development of contractile fibrils which squeeze protoplasmic sol from the area, resulting in photoavoidance.

  11. Overlap of abnormal photoreceptor development and progressive degeneration in Leber congenital amaurosis caused by NPHP5 mutation.

    Science.gov (United States)

    Downs, Louise M; Scott, Erin M; Cideciyan, Artur V; Iwabe, Simone; Dufour, Valerie; Gardiner, Kristin L; Genini, Sem; Marinho, Luis Felipe; Sumaroka, Alexander; Kosyk, Mychajlo S; Swider, Malgorzata; Aguirre, Geoffrey K; Jacobson, Samuel G; Beltran, William A; Aguirre, Gustavo D

    2016-10-01

    Ciliary defects can result in severe disorders called ciliopathies. Mutations in NPHP5 cause a ciliopathy characterized by severe childhood onset retinal blindness, Leber congenital amaurosis (LCA), and renal disease. Using the canine NPHP5-LCA model we compared human and canine retinal phenotypes, and examined the early stages of photoreceptor development and degeneration, the kinetics of photoreceptor loss, the progression of degeneration and the expression profiles of selected genes. NPHP5-mutant dogs recapitulate the human phenotype of very early loss of rods, and relative retention of the central retinal cone photoreceptors that lack function. In mutant dogs, rod and cone photoreceptors have a sensory cilium, but develop and function abnormally and then rapidly degenerate; L/M cones are more severely affected than S-cones. The lack of outer segments in mutant cones indicates a ciliary dysfunction. Genes expressed in mutant rod or both rod and cone photoreceptors show significant downregulation, while those expressed only in cones are unchanged. Many genes in cell-death and -survival pathways also are downregulated. The canine disease is a non-syndromic LCA-ciliopathy, with normal renal structures and no CNS abnormalities. Our results identify the critical time points in the pathogenesis of the photoreceptor disease, and bring us closer to defining a potential time window for testing novel therapies for translation to patients.

  12. MAS NMR study of the photoreceptor phytochrome

    NARCIS (Netherlands)

    Rohmer, Thierry

    2009-01-01

    Plants, algae and bacteria respond to light in various manners. The effect of light on the growth of plants is called photomorphogenesis and is regulated by the photoreceptor protein named phytochrome. Phytochrome is formed in the dark in its inactive red-absorbing (Pr) state and transformed upon ab

  13. Calcium homeostasis in fly photoreceptor cells

    NARCIS (Netherlands)

    Oberwinkler, J

    2002-01-01

    In fly photoreceptor cells, two processes dominate the Ca2+ homeostasis: light-induced Ca2+ influx through members of the TRP family of ion channels, and Ca2+ extrusion by Na+/Ca2+ exchange.Ca2+ release from intracellular stores is quantitatively insignificant. Both, the light-activated channels and

  14. LED蓝光治疗痤疮的临床观察%Clinical Observation of LED Blue Light in the Treatment of Acne

    Institute of Scientific and Technical Information of China (English)

    邓景航; 王菲; 高东好

    2014-01-01

    目的:探索研究LED蓝光治疗痤疮的临床效果。方法:观察组使用LED蓝光疗法与克林霉素凝胶共同治疗,对照组使用克林霉素凝胶进行治疗,观察两组的治疗效果。结果:通过对使用LED蓝光与克林霉素凝胶的观察组和使用克林霉素凝胶的对照组进行一个疗程的治疗,在使用LED蓝光与克林霉素凝胶的观察组的39例患者中,完全治愈的有19例,有效的为19例,无效的有1例,总有效率97.43%,在使用克林霉素凝胶的对照组的39例患者中,完全治愈的有11例,有效的为22例,无效的有6例,总有效率84.61%,两组在显效率及总有效率两方面比较差异显著(P<0.05),具有统计学意义,可以得出有LED蓝光治疗的观察组治疗效果比观察组好。结论:LED蓝光治疗痤疮值得临床推广。%Objective:To explore the clinical effects of LED blue light in the treatment of acne. Methods:the observation group using the LED Blu ray therapy and Ciprofloxacin Hydrochloride Cream treatment, control group using Ciprofloxacin Hydrochloride Cream treatment, observe the treatment effect of the two groups. Results:Through the observation of the use LED blue light and clindamycin gel group and control group use clindamycin gel for a course of treatment, in the use of LED blue and clindamycin gel group of 39 cases, completely cured in 19 cases, effective for 19 cases, ineffective in 1 case, the total effective rate was 97.43%; In the use of clindamycin gel with a control group of 39 cases, completely cured in 11 cases, effective in 22 cases, ineffective in 6 cases, total effective rate 84.61%, two groups in the two aspects of efficiency and total effective rate was significant difference (P<0.05), statistically significant, can draw has LED blue light treatment group therapy effect is better than the observation group. Conclusion:LED blue light in the treatment of acne is worth the clinical promotion.

  15. Performance improvement of blue light-emitting diodes with an AlInN/GaN superlattice electron-blocking layer

    Institute of Scientific and Technical Information of China (English)

    Zhao Fang; Yao Guang-Rui; Song Jing-Jing; Ding Bin-Bin; Xiong Jian-Yong; Su Chen; Zheng Shu-Wen

    2013-01-01

    The characteristics of a blue light-emitting diode (LED) with an AlInN/GaN superlattice (SL) electron-blocking layer (EBL) are analyzed numerically.The cartier concentrations in the quantum wells,energy band diagrams,electrostatic fields,and internal quantum efficiency are investigated.The results suggest that the LED with an AlInN/GaN SL EBL has better hole injection efficiency,lower electron leakage,and smaller electrostatic fields in the active region than the LED with a conventional rectangular AlGaN EBL or a A1GaN/GaN SL EBL.The results also indicate that the efficiency droop is markedly improved when an AlInN/GaN SL EBL is used.

  16. LED Blue Light-induced changes in phenolics and ethylene in citrus fruit: Implication in elicited resistance against Penicillium digitatum infection.

    Science.gov (United States)

    Ballester, Ana-Rosa; Lafuente, María T

    2017-03-01

    The objective was to investigate whether LED Blue Light (LBL) induces changes in phenolics and ethylene production of sweet oranges, and whether they participate in LBL-elicited resistance against the most important postharvest pathogen (Penicillium digitatum) of citrus fruit. The expression of relevant genes of the phenylpropanoid and ethylene biosynthetic pathways during elicitation of resistance was also determined. Different LBL (wavelength 450nm) quantum fluxes were used within the 60-630μmolm(-2)s(-1) range. The HPLC analysis showed that the most relevant increase in phenylpropanoids occurred in scoparone, which markedly increased 3days after exposing fruits to a very high quantum flux (630μmolm(-2)s(-1)) for 18h. However, phenylpropanoids, including scoparone, were not critical factors in LBL-induced resistance. The genes involved in ethylene biosynthesis were differentially regulated by LBL. Ethylene is not involved in elicited resistance, although high LBL levels increased ethylene production in only 1h.

  17. Determination of eye safety filter protection factors associated with retinal thermal hazard and blue light photochemical hazard for intense pulsed light sources

    Energy Technology Data Exchange (ETDEWEB)

    Clarkson, D McG [Department of Clinical Physics and Bioengineering, Arden Cancer Centre, Walsgrave Hospital, UHCW NHS Trust, Coventry, CV2 2DX (United Kingdom)

    2006-02-21

    An assessment is provided of protection factors afforded for retinal thermal hazard and blue light photochemical hazard for a range of filters used with intense pulsed light sources (IPLs). A characteristic IPL spectrum based on black body radiation at 5000 K with a low cut filter at 515 nm was identified as suitable for such estimations. Specific filters assessed included types with idealized transmission properties and also a range of types whose transmission characteristics were measured by means of a Bentham DMc150 spectroradiometer. Predicted behaviour based on these spectra is outlined which describes both the effectiveness of protection and the level of luminous transmittance afforded. The analysis showed it was possible to describe a figure of merit for a particular filter material relating the degree of protection provided and corresponding value of luminous transmittance. This consideration is important for providing users of IPL equipment with safety eyewear with adequate level of visual transmittance. (note)

  18. Single-wavelength-controlled in situ dynamic super-resolution fluorescence imaging for block copolymer nanostructures via blue-light-switchable FRAP.

    Science.gov (United States)

    Gong, Wen-Liang; Yan, Jie; Zhao, Ling-Xi; Li, Chong; Huang, Zhen-Li; Tang, Ben Zhong; Zhu, Ming-Qiang

    2016-11-02

    Photoswitchable fluorophores are promising in single-molecule optical devices and super-resolution fluorescence imaging, especially in single-molecule photo-activated localization microscopy (PALM) or stochastic optical reconstruction microscopy (STORM). However, the scarcity of current photoswitchable fluorophores stimulates researchers to develop complicated optical systems and processing software, in accordance with the limited photoswitchable fluorescent proteins and organic fluorophores. Previous efforts to develop synthetic photoswitchable fluorophores have exhibited their promising potential in super-resolution fluorescence imaging. Here, we have designed and synthesized a fluorescence molecular switch with reversible green emission, a napthalimide-hexaarylbiimidazole conjugate (NI-N-HABI), which exhibits strong fluorescence in the emissive state, with fast thermal fading of the photochromism and spontaneous fluorescence recovery after photobleaching (FRAP) induced by blue-light. The photoswitchable fluorophore enables the red-edge wavelength of the optical response to red-shift from the initial near-UV region at less than 400 nm, to 500 nm. The relatively fast fading speed of NI-N-HABI and its sensitivity to longer blue-light irradiation (400-500 nm) have allowed simplification of the optical microscopic system from a two-wavelength laser source to a single-wavelength laser. We applied NI-N-HABI in single-wavelength-controlled in situ dynamic super-resolution fluorescence imaging for the self-assembly and solvent annealing of amphiphilic block polymers, with 50 nm of optical resolution. Single-wavelength-controlled dynamic super-resolution fluorescence imaging facilitates nanoscale optical visualization for the dynamic physical and chemical fluctuation processes of stimuli-responsive nanostructures.

  19. Photocurrent response of B{sub 12}As{sub 2} crystals to blue light, and its temperature- dependent electrical characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Gul, R., E-mail: rubi786@yahoo.com [Brookhaven National Laboratory, Upton, NY, 11973 (United States); Alabama A& M University, Normal AL, 35762 (United States); Cui, Y.; Bolotnikov, A. E.; Camarda, G. S.; Hossain, A.; Roy, U. N.; Yang, G.; James, R. B. [Brookhaven National Laboratory, Upton, NY, 11973 (United States); Egarievwe, S. U. [Alabama A& M University, Normal AL, 35762 (United States); Edgar, J. H.; Nwagwu, U. [Kansas State University, Manhattan, KS, 66506 (United States)

    2016-02-15

    With the global shortage of {sup 3}He gas, researchers worldwide are looking for alternative materials for detecting neutrons. Among the candidate materials, semiconductors are attractive because of their light weight and ease in handling. Currently, we are looking into the suitability of boron arsenide (B{sub 12}As{sub 2}) for this specific application. As the first step in evaluating the material qualitatively, the photo-response of B{sub 12}As{sub 2} bulk crystals to light with different wavelengths was examined. The crystals showed photocurrent response to a band of 407- and 470- nm blue light. The maximum measured photoresponsivity and the photocurrent density at 0.7 V for 470 nm blue light at room temperature were 0.25 A ⋅ W{sup −1} and 2.47 mA ⋅ cm{sup −2}, respectively. In addition to photo current measurements, the electrical properties as a function of temperature (range: 50-320 K) were measured. Reliable data were obtained for the low-temperature I-V characteristics, the temperature dependence of dark current and its density, and the resistivity variations with temperature in B{sub 12}As{sub 2} bulk crystals. The experiments showed an exponential dependence on temperature for the dark current, current density, and resistivity; these three electrical parameters, respectively, had a variation of a few nA to μA, 1-100 μA ⋅ cm{sup −2} and 7.6x10{sup 5}-7.7x10{sup 3} Ω ⋅ cm, for temperature increasing from 50 K to 320 K. The results from this study reported the first photoresponse and demonstrated that B{sub 12}As{sub 2} is a potential candidate for thermal-neutron detectors.

  20. Synthesis, characterization and properties of novel blue light emitting discrete π-functional polymer consisting of carbazole and anthracene units and their applications in polymer light emitting diodes

    Science.gov (United States)

    Gopal, Ram; Huang, Yi-Chiang; Lee, Hsu-Feng; Chang, Ming-Sien; Huang, Wen-Yao

    2017-03-01

    A new novel blue light emitting polymer containing carbazole and anthracene derivatives has been successfully synthesized via polycondensation chemical reaction of diol and difluoro monomers. An effort has been made to raise the band gap of blue light emitter by lowering the conjugation extent in the backbone. The synthesized blue polymer exhibits decent solubility, good process ability, high thermal stability, high glass transition temperature (272 °C) and the decomposition temperature of 358 °C. The UV-vis absorption spectra and photoluminescence spectra depict that the light emission lies in blue region. The solid state photoluminescence (PL) spectra of the polymer (λPL=456 nm) shows red shift (Δλ = 37 nm) as compared with the corresponding solution PL spectra, presumably due to lower intermolecular distance in solid state. The multi-layered polymer light emitting diode was fabricated, using blue polymer with ITO/PEDOT: PSS/BP/LiF/Al architecture. The luminance-voltage (L-V) and current density-voltage (J-V) curves show a maximum luminance of 7544 cd m-2, a maximum emission efficiency of 4.2 cd A-1, a maximum current density of 453 mA cm-2 at a turn-on voltage of 4.5 V. Moreover, the PLED instigate pure blue EL emission, stable at 436 nm with outstanding CIE coordinates of (x = 0.15, y = 0.08), which is close to the pure NTSC blue coordinates of (0.14, 0.08). [Figure not available: see fulltext.

  1. Rare-earth-free red-emitting K2Ge4O9:Mn(4+) phosphor excited by blue light for warm white LEDs.

    Science.gov (United States)

    Ding, Xin; Wang, Qian; Wang, Yuhua

    2016-03-21

    A series of novel K2Ge4O9:Mn(4+) phosphors with red emission under blue light excitation have been synthesized successfully by traditional high-temperature solid-state reaction. The structure of K2Ge4O9 has been investigated by high-resolution transmission electron microscopy, scanning electron microscopy and X-ray powder diffraction with Rietveld refinement. The PL properties have been investigated by measuring diffuse reflection spectra, emission spectra, excitation spectra, decay curves and temperature-dependent spectra. The KGO:0.1% Mn(4+) phosphor can emit red light peaking at 663 nm under UV or blue light excitation. The critical quenching concentration of Mn(4+) was about 0.1 mol%. The concentration quenching mechanism could be a d-d interaction for the Mn(4+) center. The CIE chromaticity coordinates and FWHM are (0.702, 0.296) and 20 nm, which demonstrated that the K2Ge4O9:Mn(4+) has a high color purity. By tuning the weight ratio of yellow and red phosphors, the fabricated white LEDs, using a 455 nm InGaN blue chip combined with a blend of the yellow phosphor YAG:Ce(3+) and the red-emitting KGO:Mn(4+) phosphor driven by a 40 mA current, can get white light with chromaticity coordinates (0.405, 0.356) and CCT 3119 K. These results indicated that K2Ge4O9:Mn(4+) is a potential red phosphor to match blue LED chips to get warm white light.

  2. Integrated role of ROS and Ca(+2) in blue light-induced chloroplast avoidance movement in leaves of Hydrilla verticillata (L.f.) Royle.

    Science.gov (United States)

    Majumdar, Arkajo; Kar, Rup Kumar

    2016-11-01

    Directional chloroplast photorelocation is a major physio-biochemical mechanism that allows these organelles to realign themselves intracellularly in response to the intensity of the incident light as an adaptive response. Signaling processes involved in blue light (BL)-dependent chloroplast movements were investigated in Hydrilla verticillata (L.f.) Royle leaves. Treatments with antagonists of actin filaments [2,3,5-triiodobenzoic acid (TIBA)] and microtubules (oryzalin) revealed that actin filaments, but not microtubules, play a pivotal role in chloroplast movement. Involvement of reactive oxygen species (ROS) in controlling chloroplast avoidance movement has been demonstrated, as exogenous H2O2 not only accelerated chloroplast avoidance but also could induce chloroplast avoidance even in weak blue light (WBL). Further support came from experiments with different ROS scavengers, i.e., dimethylthiourea (DMTU), KI, and CuCl2, which inhibited chloroplast avoidance, and from ROS localization using specific stains. Such avoidance was also partially inhibited by ZnCl2, an inhibitor of NADPH oxidase (NOX) as well as 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), a photosynthetic electron transport chain (ETC) inhibitor at PS II. However, methyl viologen (MV), a PS I ETC inhibitor, rather accelerated avoidance response. Exogenous calcium (Ca(+2)) induced avoidance even in WBL while inhibited chloroplast accumulation partially. On the other hand, chloroplast movements (both accumulation and avoidance) were blocked by Ca(+2) antagonists, La(3+) (inhibitor of plasma membrane Ca(+2) channel) and ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA, Ca(+2) chelator) while LiCl that affects Ca(+2) release from endosomal compartments did not show any effect. A model on integrated role of ROS and Ca(+2) (influx from apolastic space) in actin-mediated chloroplast avoidance has been proposed.

  3. Photobiomodulation of distinct lineages of human dermal fibroblasts: a rational approach towards the selection of effective light parameters for skin rejuvenation and wound healing

    Science.gov (United States)

    Mignon, Charles; Uzunbajakava, Natallia E.; Raafs, Bianca; Moolenaar, Mitchel; Botchkareva, Natalia V.; Tobin, Desmond J.

    2016-03-01

    Distinct lineages of human dermal fibroblasts play complementary roles in skin rejuvenation and wound healing, which makes them a target of phototherapy. However, knowledge about differential responses of specific cell lineages to different light parameters and moreover the actual molecular targets remain to be unravelled. The goal of this study was to investigate the impact of a range of parameters of light on the metabolic activity, collagen production, and cell migration of distinct lineages of human dermal fibroblasts. A rational approach was used to identify parameters with high therapeutic potential. Fibroblasts exhibited both inhibitory and cytotoxic change when exposed to a high dose of blue and cyan light in tissue culture medium containing photo-reactive species, but were stimulated by high dose red and near infrared light. Cytotoxic effects were eliminated by refreshing the medium after light exposure by removing potential ROS formed by extracellular photo-reactive species. Importantly, distinct lineages of fibroblasts demonstrated opposite responses to low dose blue light treatment when refreshing the medium after exposure. Low dose blue light treatment also significantly increased collagen production by papillary fibroblasts; high dose significantly retarded closure of the scratch wound without signs of cytotoxicity, and this is likely to have involved effects on both cell migration and proliferation. We recommend careful selection of fibroblast subpopulations and their culture conditions, a systematic approach in choosing and translating treatment parameters, and pursuit of fundamental research on identification of photoreceptors and triggered molecular pathways, while seeking effective parameters to address different stages of skin rejuvenation and wound healing.

  4. Short-term psychosocial stress protects photoreceptors from damage via corticosterone-mediated activation of the AKT pathway.

    Science.gov (United States)

    Forkwa, Tembei K; Neumann, Inga D; Tamm, Ernst R; Ohlmann, Andreas; Reber, Stefan O

    2014-02-01

    Apoptotic death of photoreceptors in hereditary retinal degenerations can be prevented by neuroprotective molecules. Here, we report that adrenal glucocorticoids (GC) released during psychosocial stress protect photoreceptors from apoptosis after light damage. Psychosocial stress is known to be the main type of stressor humans are exposed to and was induced here in mice by 10h of chronic subordinate colony housing (CSC). Photoreceptor damage was generated by subsequent exposure to white light. Short-term psychosocial stress prior to illumination significantly reduced the number of apoptotic photoreceptors, an effect that was absent in adrenalectomized (ADX) mice. The neuroprotective effect was completely restored in ADX mice substituted with GC. Moreover, phosphorylation of retinal AKT increased following CSC or exogenous GC treatment, an effect that was again absent in ADX mice exposed to CSC. Finally, inhibition of AKT signaling with triciribine blocked the stress- and GC-mediated neuroprotective effects on photoreceptors. In summary, we provide evidence that 1) short-term psychosocial stress protects photoreceptors from light-induced damage and 2) the protective effect is most likely mediated by GC-induced activation of the AKT signaling pathway.

  5. Distinct and atypical intrinsic and extrinsic cell death pathways between photoreceptor cell types upon specific ablation of Ranbp2 in cone photoreceptors.

    Directory of Open Access Journals (Sweden)

    Kyoung-In Cho

    2013-06-01

    Full Text Available Non-autonomous cell-death is a cardinal feature of the disintegration of neural networks in neurodegenerative diseases, but the molecular bases of this process are poorly understood. The neural retina comprises a mosaic of rod and cone photoreceptors. Cone and rod photoreceptors degenerate upon rod-specific expression of heterogeneous mutations in functionally distinct genes, whereas cone-specific mutations are thought to cause only cone demise. Here we show that conditional ablation in cone photoreceptors of Ran-binding protein-2 (Ranbp2, a cell context-dependent pleiotropic protein linked to neuroprotection, familial necrotic encephalopathies, acute transverse myelitis and tumor-suppression, promotes early electrophysiological deficits, subcellular erosive destruction and non-apoptotic death of cones, whereas rod photoreceptors undergo cone-dependent non-autonomous apoptosis. Cone-specific Ranbp2 ablation causes the temporal activation of a cone-intrinsic molecular cascade highlighted by the early activation of metalloproteinase 11/stromelysin-3 and up-regulation of Crx and CoREST, followed by the down-modulation of cone-specific phototransduction genes, transient up-regulation of regulatory/survival genes and activation of caspase-7 without apoptosis. Conversely, PARP1+ -apoptotic rods develop upon sequential activation of caspase-9 and caspase-3 and loss of membrane permeability. Rod photoreceptor demise ceases upon cone degeneration. These findings reveal novel roles of Ranbp2 in the modulation of intrinsic and extrinsic cell death mechanisms and pathways. They also unveil a novel spatiotemporal paradigm of progression of neurodegeneration upon cell-specific genetic damage whereby a cone to rod non-autonomous death pathway with intrinsically distinct cell-type death manifestations is triggered by cell-specific loss of Ranbp2. Finally, this study casts new light onto cell-death mechanisms that may be shared by human dystrophies with distinct

  6. Insect photoreceptor adaptations to night vision.

    Science.gov (United States)

    Honkanen, Anna; Immonen, Esa-Ville; Salmela, Iikka; Heimonen, Kyösti; Weckström, Matti

    2017-04-05

    Night vision is ultimately about extracting information from a noisy visual input. Several species of nocturnal insects exhibit complex visually guided behaviour in conditions where most animals are practically blind. The compound eyes of nocturnal insects produce strong responses to single photons and process them into meaningful neural signals, which are amplified by specialized neuroanatomical structures. While a lot is known about the light responses and the anatomical structures that promote pooling of responses to increase sensitivity, there is still a dearth of knowledge on the physiology of night vision. Retinal photoreceptors form the first bottleneck for the transfer of visual information. In this review, we cover the basics of what is known about physiological adaptations of insect photoreceptors for low-light vision. We will also discuss major enigmas of some of the functional properties of nocturnal photoreceptors, and describe recent advances in methodologies that may help to solve them and broaden the field of insect vision research to new model animals.This article is part of the themed issue 'Vision in dim light'.

  7. Acute Zonal Cone Photoreceptor Outer Segment Loss.

    Science.gov (United States)

    Aleman, Tomas S; Sandhu, Harpal S; Serrano, Leona W; Traband, Anastasia; Lau, Marisa K; Adamus, Grazyna; Avery, Robert A

    2017-05-01

    The diagnostic path presented narrows down the cause of acute vision loss to the cone photoreceptor outer segment and will refocus the search for the cause of similar currently idiopathic conditions. To describe the structural and functional associations found in a patient with acute zonal occult photoreceptor loss. A case report of an adolescent boy with acute visual field loss despite a normal fundus examination performed at a university teaching hospital. Results of a complete ophthalmic examination, full-field flash electroretinography (ERG) and multifocal ERG, light-adapted achromatic and 2-color dark-adapted perimetry, and microperimetry. Imaging was performed with spectral-domain optical coherence tomography (SD-OCT), near-infrared (NIR) and short-wavelength (SW) fundus autofluorescence (FAF), and NIR reflectance (REF). The patient was evaluated within a week of the onset of a scotoma in the nasal field of his left eye. Visual acuity was 20/20 OU, and color vision was normal in both eyes. Results of the fundus examination and of SW-FAF and NIR-FAF imaging were normal in both eyes, whereas NIR-REF imaging showed a region of hyporeflectance temporal to the fovea that corresponded with a dense relative scotoma noted on light-adapted static perimetry in the left eye. Loss in the photoreceptor outer segment detected by SD-OCT co-localized with an area of dense cone dysfunction detected on light-adapted perimetry and multifocal ERG but with near-normal rod-mediated vision according to results of 2-color dark-adapted perimetry. Full-field flash ERG findings were normal in both eyes. The outer nuclear layer and inner retinal thicknesses were normal. Localized, isolated cone dysfunction may represent the earliest photoreceptor abnormality or a distinct entity within the acute zonal occult outer retinopathy complex. Acute zonal occult outer retinopathy should be considered in patients with acute vision loss and abnormalities on NIR-REF imaging, especially if

  8. Impaired Mitochondrial Energy Production Causes Light-Induced Photoreceptor Degeneration Independent of Oxidative Stress.

    Directory of Open Access Journals (Sweden)

    Manish Jaiswal

    2015-07-01

    Full Text Available Two insults often underlie a variety of eye diseases including glaucoma, optic atrophy, and retinal degeneration--defects in mitochondrial function and aberrant Rhodopsin trafficking. Although mitochondrial defects are often associated with oxidative stress, they have not been linked to Rhodopsin trafficking. In an unbiased forward genetic screen designed to isolate mutations that cause photoreceptor degeneration, we identified mutations in a nuclear-encoded mitochondrial gene, ppr, a homolog of human LRPPRC. We found that ppr is required for protection against light-induced degeneration. Its function is essential to maintain membrane depolarization of the photoreceptors upon repetitive light exposure, and an impaired phototransduction cascade in ppr mutants results in excessive Rhodopsin1 endocytosis. Moreover, loss of ppr results in a reduction in mitochondrial RNAs, reduced electron transport chain activity, and reduced ATP levels. Oxidative stress, however, is not induced. We propose that the reduced ATP level in ppr mutants underlies the phototransduction defect, leading to increased Rhodopsin1 endocytosis during light exposure, causing photoreceptor degeneration independent of oxidative stress. This hypothesis is bolstered by characterization of two other genes isolated in the screen, pyruvate dehydrogenase and citrate synthase. Their loss also causes a light-induced degeneration, excessive Rhodopsin1 endocytosis and reduced ATP without concurrent oxidative stress, unlike many other mutations in mitochondrial genes that are associated with elevated oxidative stress and light-independent photoreceptor demise.

  9. Rpr- and hid-driven cell death in Drosophila photoreceptors.

    Science.gov (United States)

    Hsu, Cheng Da; Adams, Sheila M; O'Tousa, Joseph E

    2002-02-01

    The reaper (rpr) and head involution defective (hid) genes mediate programmed cell death (PCD) during Drosophila development. We show that expression of either rpr or hid under control of a rhodopsin promoter induces rapid cell death of adult photoreceptor cells. Ultrastructural analysis revealed that the dying photoreceptor cells share morphological features with other cells undergoing PCD. The anti-apoptotic baculoviral P35 protein acts downstream of hid activity to suppress the photoreceptor cell death driven by rpr and hid. These results establish that the Drosophila photoreceptors are sensitive to the rpr- and hid-driven cell death pathways.

  10. Ultrafast Structural Dynamics of BlsA, a Photoreceptor from the Pathogenic Bacterium Acinetobacter baumannii

    Science.gov (United States)

    2013-01-01

    Acinetobacter baumannii is an important human pathogen that can form biofilms and persist under harsh environmental conditions. Biofilm formation and virulence are modulated by blue light, which is thought to be regulated by a BLUF protein, BlsA. To understand the molecular mechanism of light sensing, we have used steady-state and ultrafast vibrational spectroscopy to compare the photoactivation mechanism of BlsA to the BLUF photosensor AppA from Rhodobacter sphaeroides. Although similar photocycles are observed, vibrational data together with homology modeling identify significant differences in the β5 strand in BlsA caused by photoactivation, which are proposed to be directly linked to downstream signaling. PMID:24723998

  11. A dual-blue light-emitting diode based on strain-compensated InGaN-AlGaN/GaN quantum wells

    Institute of Scientific and Technical Information of China (English)

    Yan Qi-Rong; Yan Qi-Ang; Shi Pei-Pei; Niu Qiao-Li; Li Shu-Ti; Zhang Yong

    2013-01-01

    A strain-compensated InGaN quantum well (QW) active region employing a tensile A1GaN barrier is analyzed.Its spectral stability and efficiency droop for a dual-blue light-emitting diode (LED) are improved compared with those of the conventional InGaN/GaN QW dual-blue LEDs based on a stacking structure of two In0.18Ga0.82N/GaN QWs and two In0.12Ga0.88N/GaN QWs on the same sapphire substrate.It is found that the optimal performance is achieved when the AI composition of the strain-compensated A1GaN layer is 0.12 in blue QW and 0.21 in blue-violet QW.The improvement performance can be attributed to the strain-compensated InGaN-AlGaN/GaN QW,which can provide a better carrier confinement and effectively reduce leakage current.

  12. Phototherapy with blue and green mixed-light is as effective against unconjugated jaundice as blue light and reduces oxidative stress in the Gunn rat model.

    Science.gov (United States)

    Uchida, Yumiko; Morimoto, Yukihiro; Uchiike, Takao; Kamamoto, Tomoyuki; Hayashi, Tamaki; Arai, Ikuyo; Nishikubo, Toshiya; Takahashi, Yukihiro

    2015-07-01

    Phototherapy using blue light-emitting diodes (LED) is effective against neonatal jaundice. However, green light phototherapy also reduces unconjugated jaundice. We aimed to determine whether mixed blue and green light can relieve jaundice with minimal oxidative stress as effectively as either blue or green light alone in a rat model. Gunn rats were exposed to phototherapy with blue (420-520 nm), filtered blue (FB; 440-520 nm withoutgreen), and green (490-590 nm) LED irradiation for 24h. The effects of phototherapy are expressed as ratios of serum total (TB) and unbound (UB) bilirubin before and after exposure to each LED. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) was measured by HPLC before and after exposure to each LED to determine photo-oxidative stress. Values green LED, respectively. In contrast, urinary 8-OHdG increased to 2.03, 1.25, 0.96, 1.36, 1.31, and 1.23 after exposure to blue, filtered blue, FB50, mixed, green LED, and control, indicating side-effects (> 1.00), respectively. Blue plus green phototherapy is as effective as blue phototherapy and it attenuates irradiation-induced oxidative stress. Combined blue and green spectra might be effective against neonatal hyperbilirubinemia. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  13. SYNTHESIS AND CHARACTERIZATION OF BLUE LIGHT-EMITTING POLY(ARYL ETHER)S CONTAINING PYRIMIDINE-INCORPORATED OLIGOFLUORENE PENDANTS WITH BIPOLAR FEATURE

    Institute of Scientific and Technical Information of China (English)

    Guo-xin Jiang; Chun-lei Bian; Jun-qiao Ding; Li-xiang Wang

    2013-01-01

    Novel blue light-emitting poly(aryl ether)s comprising of bipolar oligofluorene pendants as chromophores have been designed and synthesized,in which pyrimidine and arylamine moieties are utilized as the electron acceptor and electron donor,respectively.Through varying π bridge length from monofluorene to bifluorene and end-cappers from hydrogen to carbazole and diphenylamine,the emission color of the resulting polymers covers from deep blue to greenish blue,and their HOMO and LUMO levels can be modulated to facilitate charge injection to improve the device performance.Polymer lightemitting diodes (PLEDs) are fabricated with the device structure of ITO/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) (50 nm)/polymer (80 nm)/Ca (10 nm)/A1 (200 nm).Among these polymers,P2Cz5F-Py with bifluorene bridge and carbazole end-capper shows excellent trade-off between the efficiency and emission wavelength,having a peak luminous efficiency as high as 1.26 cd/A and Commission Internationale de L'Eclairage (CIE) coordinates of (0.17,0.17).

  14. New blue-light-emitting ultralong [Cd(L)(TeO3)] (L = polyamine) organic-inorganic hybrid nanofibre bundles: their thermal stability and acidic sensitivity.

    Science.gov (United States)

    Yao, Hong-Bin; Li, Xiao-Bo; Yu, Shu-Hong

    2009-08-03

    A new type of blue-light-emitting ultralong [Cd(L)(TeO(3))] (L = ethylenediamine, diethylenetriamine) nanofibre bundle has been synthesised under reflux in a mixed solvent media. Inorganic Cd(TeO(3)) layers are assumed to exist in the structures and are connected by the organic amine molecules through the coordination between nitrogen atoms and cadmium ions. The composition and formulae of these hybrid materials, based on the proposed structures, have been identified through element analysis (EA), thermal gravity analysis (TGA) and energy dispersive spectra (EDS). The thermal stabilities and optical properties of these nanofibre bundles have been investigated. Thermal decomposition of [Cd(en)(TeO(3))] (en = ethylenediamine) and [Cd(DETA)(TeO(3))] (DETA = diethylenetriamine) at 450 degrees C allowed the formation of a mixture of CdTe and Cd(TeO(3)) phases, and a pure CdTe phase, respectively. In addition, this new kind of hybrid bundle, which demonstrates blue emission, was found to be sensitive to acids, and the emission intensity is strongly dependent on the acidity of the solutions, implying that these hybrid nanofibre bundles could be potentially applied as acid sensors.

  15. Effect of high-temperature/current stress on the forward tunneling current of InGaN/GaN high-power blue-light-emitting diodes

    Science.gov (United States)

    Liu, Sheng; Zheng, Chenju; Lv, Jiajiang; Liu, Mengling; Zhou, Shengjun

    2017-08-01

    Through the analysis of the temperature-dependent current-voltage (I-V) characteristics of the fabricated InGaN/GaN high-power blue-light-emitting diodes (LEDs), the low-bias region was confirmed to be dominated by tunneling current, while the medium-bias region was dominated by diffusion-recombination current. Electrons and heavy holes appeared to play similar roles in the tunneling current of the fabricated LEDs, with no apparent dominant tunneling entity determined by characteristic energy as previous works suggested. After 1000 h of high-temperature/current stress, the medium-bias regions of the I-V curves of LEDs remained almost unchanged, while the current in the low-bias region was greatly enhanced by the stress, which confirmed the different carrier transport mechanism behaviors in the low- and medium-bias regions. Further comparison between the I-V characteristics of the unstressed and stressed LEDs suggested that the change in I-V curve was associated with the increase in defect density and the apparent doping concentration in the InGaN/GaN multiple-quantum-well (MQW) active region.

  16. Sr9Mg(1.5)(PO4)7:Eu(2+): A Novel Broadband Orange-Yellow-Emitting Phosphor for Blue Light-Excited Warm White LEDs.

    Science.gov (United States)

    Sun, Wenzhi; Jia, Yonglei; Pang, Ran; Li, Haifeng; Ma, Tengfei; Li, Da; Fu, Jipeng; Zhang, Su; Jiang, Lihong; Li, Chengyu

    2015-11-18

    A new orange-yellow-emitting Sr9Mg(1.5)(PO4)7:Eu(2+) phosphor was prepared via high-temperature solid-state reaction. The structure and optical properties of it were studied systematically. Sr9Mg(1.5)(PO4)7:Eu(2+) can be well-excited by 460 nm blue InGaN chips and exhibit a wide emission band covering from 470 to 850 nm with two main peaks centered at 523 and 620 nm, respectively, which originate from 5d-4f dipole-allowed transitions of Eu(2+) in different crystallographic sites. The sites attribution, concentration quenching, fluorescence decay analysis, and temperature-dependent luminescence properties were investigated in detail. Furthermore, a warm white LED device was fabricated by combining a 460 nm blue InGaN chip with the optimized orange-yellow-emitting Sr9Mg(1.5)(PO4)7:Eu(2+). The color coordinate, correlated color temperature and color rendering index of the fabricated LED device were (0.393, 0.352), 3437 K, and 86.07, respectively. Sr9Mg(1.5)(PO4)7:Eu(2+) has great potential to serve as an attractive candidate in the application of blue light-excited warm white LEDs.

  17. Blue light emitting Y2O3:Tm3 + nanophosphors with tunable morphology obtained by bio-surfactant assisted sonochemical route

    Science.gov (United States)

    Venkatachalaiah, K. N.; Nagabhushana, H.; Darshan, G. P.; Basavaraj, R. B.; Daruka Prasad, B.; Sharma, S. C.

    2017-09-01

    Modified sonochemical route was used to prepare Y2O3:Tm3+ (1-11 mol%) nanophosphor using Mimosa pudica (M.P.) leaves extract as bio-surfactant. The prepared samples were exhibited high crystalline nature with various morphologies. This was due to sonochemical experimental reaction took place between cavitation bubbles and nearby solution. The average crystallite sizes of the prepared samples were about 15 nm to 21 nm as obtained from PXRD and TEM analysis. The ultraviolet visible absorption spectra showed prominent bands with an energy gap varied from 5.73 eV to 5.84 eV. Photoluminescence (PL) emission spectra shows the prominent blue light emission peak at 456 nm attributed to 1D2 → 3F4 transitions of Tm3+ ions. Judd-Ofelt intensity parameters were estimated by using PL emission spectra. The photometric characteristics of the prepared compounds were very close to the blue color of NTSC standards. So the results were fruitful in making use of Y2O3:Tm3 + nanophosphor as an alternative material for effective blue component in WLED's.

  18. MerR and ChrR mediate blue light induced photo-oxidative stress response at the transcriptional level in Vibrio cholerae

    Science.gov (United States)

    Tardu, Mehmet; Bulut, Selma; Kavakli, Ibrahim Halil

    2017-01-01

    Blue light (BL) is a major environmental factor that affects the physiology, behavior, and infectivity of bacteria as it contributes to the generation of reactive oxygen species (ROS) while increasing photo-oxidative stress in cells. However, precise photo-oxidative response mechanism in non-phototrophic bacteria is yet to be elucidated. In this study, we investigated the effect of BL in Vibrio cholerae by using genetics and transcriptome profiling. Genome-wide analysis revealed that transcription of 6.3% of V. cholerae genes were regulated by BL. We further showed that BL enhances ROS production, which is generated through the oxidative phosphorylation. To understand signaling mechanisms, we generated several knockouts and analyzed their transcriptome under BL exposure. Studies with a double-knockout confirm an anti-sigma factor (ChrR) and putative metalloregulatory-like protein (MerR) are responsible for the genome-wide regulation to BL response in V. cholerae. Collectively, these results demonstrate that MerR-like proteins, in addition to ChrR, are required for V. cholerae to mount an appropriate response against photo-oxidative stress induced by BL. Outside its natural host, V. cholerae can survive for extended periods in natural aquatic environments. Therefore, the regulation of light response for V. cholerae may be a critical cellular process for its survival in these environments. PMID:28098242

  19. Nitrogen-doped TiO2 modified with NH4F for efficient photocatalytic degradation of formaldehyde under blue light-emitting diodes.

    Science.gov (United States)

    Li, Yuexiang; Jiang, Yuan; Peng, Shaoqin; Jiang, Fengyi

    2010-10-15

    A nitrogen-doped TiO(2) (N-TiO(2)) photocatalyst was prepared by calcination of the hydrolysis precipitate of Ti(SO(4))(2) with aqueous ammonia. The prepared N-TiO(2) was treated with NH(4)F (F-N-TiO(2)) by an impregnation-calcination method. The photocatalyst (F-N-TiO(2)) was characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), UV-vis diffusive reflectance spectroscopy (DRS), BET and X-ray photoelectron spectroscopy (XPS). With blue light-emitting diode (LED) as the light source, its photocatalytic activity for the degradation of formaldehyde was investigated. NH(4)F treatment enhances markedly photocatalytic activity of N-TiO(2). The treatment increases the visible absorption of N-TiO(2), decreases its specific surface area and influences the concentration of oxygen vacancies in N-TiO(2). Photocatalytic activity of F-N-TiO(2) depends on the visible absorption, the specific surface area, and the concentration of oxygen vacancies. The preparation conditions, such as the calcination temperature and the initial molar ratio of NH(4)F to N-TiO(2), have a significant influence on the photocatalytic activity. The doping mechanism of NH(4)F was investigated.

  20. Estimation of safe exposure time from an ophthalmic operating microscope with regard to ultraviolet radiation and blue-light hazards to the eye

    Science.gov (United States)

    Michael, Ralph; Wegener, Alfred

    2004-08-01

    Hazards from the optical radiation of an operating microscope that cause damage at the corneal, lenticular, and retinal levels were investigated; we considered, in particular, ultraviolet radiation (UVR) and blue light. The spectral irradiance from a Zeiss operation microscope OPMI VISU 200 was measured in the corneal plane between 300 and 1100 nm. Effective irradiance and radiance were calculated with relative spectral effectiveness data from the American Conference for Governmental and Industrial Hygienists. Safe exposure time to avoid UVR injury to the lens and cornea was found to be 2 h without a filter, 4 h with a UVR filter, 200 h with a yellow filter, and 400 h with a filter combination. Safe exposure time to avoid retinal photochemical injury was found to be 3 min without a filter and with a UVR filter, 10 min with a yellow filter, and 49 min with a filter combination. The effective radiance limit for retinal thermal injury was not exceeded. The hazard due to the UVR component from the operating microscope is not critical, and operation time can be safely prolonged with the use of appropriate filters. The retinal photochemical hazard appears critical without appropriate filters, permitting only some minutes of safe exposure time. The calculated safe exposure times are for worst-case conditions and maximal light output and include a safety factor.

  1. Differentiation of induced pluripotent stem cells of swine into rod photoreceptors and their integration into the retina.

    Science.gov (United States)

    Zhou, Liang; Wang, Wei; Liu, Yongqing; Fernandez de Castro, Juan; Ezashi, Toshihiko; Telugu, Bhanu Prakash V L; Roberts, R Michael; Kaplan, Henry J; Dean, Douglas C

    2011-06-01

    Absence of a regenerative pathway for damaged retina following injury or disease has led to experiments using stem cell transplantation for retinal repair, and encouraging results have been obtained in rodents. The swine eye is a closer anatomical and physiological match to the human eye, but embryonic stem cells have not been isolated from pig, and photoreceptor differentiation has not been demonstrated with induced pluripotent stem cells (iPSCs) of swine. Here, we subjected iPSCs of swine to a rod photoreceptor differentiation protocol consisting of floating culture as embryoid bodies followed by differentiation in adherent culture. Real-time PCR and immunostaining of differentiated cells demonstrated loss of expression of the pluripotent genes POU5F1, NANOG, and SOX2 and induction of rod photoreceptor genes RCVRN, NRL, RHO, and ROM1. While these differentiated cells displayed neuronal morphology, culturing on a Matrigel substratum triggered a further morphological change resulting in concentration of rhodopsin (RHO) and rod outer segment-specific membrane protein 1 in outer segment-like projections resembling those on primary cultures of rod photoreceptors. The differentiated cells were transplanted into the subretinal space of pigs treated with iodoacetic acid to eliminate rod photoreceptors. Three weeks after transplantation, engrafted RHO+ cells were evident in the outer nuclear layer where photoreceptors normally reside. A portion of these transplanted cells had generated projections resembling outer segments. These results demonstrate that iPSCs of swine can differentiate into photoreceptors in culture, and these cells can integrate into the damaged swine neural retina, thus, laying a foundation for future studies using the pig as a model for retinal stem cell transplantation.

  2. 蛹虫草蓝光诱导两步法发酵产类胡萝卜素%Two-step Fermentation of Carotenoid by Blue Light Induction in Cordyceps militaris L.

    Institute of Scientific and Technical Information of China (English)

    沈俊良; 金华燕; 高雅; 查美玲; 付鸣佳

    2013-01-01

    Utilizing the dark shake flask culture and the static culture of blue light irradiation in the two-step fermentation, the blue light induced the carotenoid production of Cordyceps militaris L mycelia. The results showed that after 2 days shake flask in the darkness and 5 days static culture in the blue light, Cordyceps militaris L carotenoid content reached a maximum value 558. 4μg/gFW. But adopting the dark shake flask culture of 2 days and different times static culture in blue light, the results show that for the first 2 days of blue light irradiation, the increase of Cordyceps militaris carotenoids content was not obvious, then a rapid increase was obtained and a maximum 558.4μg/gFW was reached in the fifth day, subsequently the content of carotenoids did not significantly change. The problem about imposed blue light is solved in the carotenoid production of Cordyceps militaris L fermentation.%采用黑暗摇瓶发酵和蓝光照射静置培养的两步培养法,进行蛹虫草(Cordyceps militaris L.)液体发酵产类胡萝卜素的蓝光诱导.结果表明蛹虫草在2d的黑暗培养和5d的蓝光照射静置培养后,其类胡萝卜素的含量可达到最高值558.4μg/gFW.而以黑暗摇瓶培养2d后,进行不同时间的蓝光照射静置培养.结果表明,蓝光照射最初2d,蛹虫草类胡萝卜素含量变化不明显,随后快速增加,并在第5天达到最大值558.4μg/gFW,随后类胡萝卜素的含量并无明显变化.通过研究解决了蛹虫草液体发酵产类胡萝卜素的培养过程中蓝光的给光问题.

  3. Specialized photoreceptor composition in the raptor fovea.

    Science.gov (United States)

    Mitkus, Mindaugas; Olsson, Peter; Toomey, Matthew B; Corbo, Joseph C; Kelber, Almut

    2017-02-15

    The retinae of many bird species contain a depression with high photoreceptor density known as the fovea. Many species of raptors have two foveae, a deep central fovea and a shallower temporal fovea. Birds have six types of photoreceptors: rods, active in dim light, double cones that are thought to mediate achromatic discrimination, and four types of single cones mediating color vision. To maximize visual acuity, the fovea should only contain photoreceptors contributing to high-resolution vision. Interestingly, it has been suggested that raptors might lack double cones in the fovea. We used transmission electron microscopy and immunohistochemistry to evaluate this claim in five raptor species: the common buzzard (Buteo buteo), the honey buzzard (Pernis apivorus), the Eurasian sparrowhawk (Accipiter nisus), the red kite (Milvus milvus) and the peregrine falcon (Falco peregrinus). We found that all species, except the Eurasian sparrowhawk, lack double cones in the center of the central fovea. The size of the double cone-free zone differed between species. Only the common buzzard had a double cone-free zone in the temporal fovea. In three species, we examined opsin expression in the central fovea and found evidence that rod opsin positive cells were absent and violet-sensitive cone and green-sensitive cone opsin positive cells were present. We conclude that not only double cones, but also single cones may contribute to high-resolution vision in birds, and that raptors may in fact possess high-resolution tetrachromatic vision in the central fovea. This article is protected by copyright. All rights reserved.

  4. Transcriptional regulation of rod photoreceptor homeostasis revealed by in vivo NRL targetome analysis.

    Directory of Open Access Journals (Sweden)

    Hong Hao

    Full Text Available A stringent control of homeostasis is critical for functional maintenance and survival of neurons. In the mammalian retina, the basic motif leucine zipper transcription factor NRL determines rod versus cone photoreceptor cell fate and activates the expression of many rod-specific genes. Here, we report an integrated analysis of NRL-centered gene regulatory network by coupling chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-Seq data from Illumina and ABI platforms with global expression profiling and in vivo knockdown studies. We identified approximately 300 direct NRL target genes. Of these, 22 NRL targets are associated with human retinal dystrophies, whereas 95 mapped to regions of as yet uncloned retinal disease loci. In silico analysis of NRL ChIP-Seq peak sequences revealed an enrichment of distinct sets of transcription factor binding sites. Specifically, we discovered that genes involved in photoreceptor function include binding sites for both NRL and homeodomain protein CRX. Evaluation of 26 ChIP-Seq regions validated their enhancer functions in reporter assays. In vivo knockdown of 16 NRL target genes resulted in death or abnormal morphology of rod photoreceptors, suggesting their importance in maintaining retinal function. We also identified histone demethylase Kdm5b as a novel secondary node in NRL transcriptional hierarchy. Exon array analysis of flow-sorted photoreceptors in which Kdm5b was knocked down by shRNA indicated its role in regulating rod-expressed genes. Our studies identify candidate genes for retinal dystrophies, define cis-regulatory module(s for photoreceptor-expressed genes and provide a framework for decoding transcriptional regulatory networks that dictate rod homeostasis.

  5. Otx2 gene deletion in adult mouse retina induces rapid RPE dystrophy and slow photoreceptor degeneration.

    Directory of Open Access Journals (Sweden)

    Francis Béby

    Full Text Available BACKGROUND: Many developmental genes are still active in specific tissues after development is completed. This is the case for the homeobox gene Otx2, an essential actor of forebrain and head development. In adult mouse, Otx2 is strongly expressed in the retina. Mutations of this gene in humans have been linked to severe ocular malformation and retinal diseases. It is, therefore, important to explore its post-developmental functions. In the mature retina, Otx2 is expressed in three cell types: bipolar and photoreceptor cells that belong to the neural retina and retinal pigment epithelium (RPE, a neighbour structure that forms a tightly interdependent functional unit together with photoreceptor cells. METHODOLOGY/PRINCIPAL FINDINGS: Conditional self-knockout was used to address the late functions of Otx2 gene in adult mice. This strategy is based on the combination of a knock-in CreERT2 allele and a floxed allele at the Otx2 locus. Time-controlled injection of tamoxifen activates the recombinase only in Otx2 expressing cells, resulting in selective ablation of the gene in its entire domain of expression. In the adult retina, loss of Otx2 protein causes slow degeneration of photoreceptor cells. By contrast, dramatic changes of RPE activity rapidly occur, which may represent a primary cause of photoreceptor disease. CONCLUSIONS: Our novel mouse model uncovers new Otx2 functions in adult retina. We show that this transcription factor is necessary for long-term maintenance of photoreceptors, likely through the control of specific activities of the RPE.

  6. Up-regulation of tumor necrosis factor superfamily genes in early phases of photoreceptor degeneration.

    Directory of Open Access Journals (Sweden)

    Sem Genini

    Full Text Available We used quantitative real-time PCR to examine the expression of 112 genes related to retinal function and/or belonging to known pro-apoptotic, cell survival, and autophagy pathways during photoreceptor degeneration in three early-onset canine models of human photoreceptor degeneration, rod cone dysplasia 1 (rcd1, X-linked progressive retinal atrophy 2 (xlpra2, and early retinal degeneration (erd, caused respectively, by mutations in PDE6B, RPGRORF15, and STK38L. Notably, we found that expression and timing of differentially expressed (DE genes correlated with the cell death kinetics. Gene expression profiles of rcd1 and xlpra2 were similar; however rcd1 was more severe as demonstrated by the results of the TUNEL and ONL thickness analyses, a greater number of genes that were DE, and the identification of altered expression that occurred at earlier time points. Both diseases differed from erd, where a smaller number of genes were DE. Our studies did not highlight the potential involvement of mitochondrial or autophagy pathways, but all three diseases were accompanied by the down-regulation of photoreceptor genes, and up-regulation of several genes that belong to the TNF superfamily, the extrinsic apoptotic pathway, and pro-survival pathways. These proteins were expressed by different retinal cells, including horizontal, amacrine, ON bipolar, and Müller cells, and suggest an interplay between the dying photoreceptors and inner retinal cells. Western blot and immunohistochemistry results supported the transcriptional regulation for selected proteins. This study highlights a potential role for signaling through the extrinsic apoptotic pathway in early cell death events and suggests that retinal cells other than photoreceptors might play a primary or bystander role in the degenerative process.

  7. Transcriptional regulation of rod photoreceptor homeostasis revealed by in vivo NRL targetome analysis.

    Science.gov (United States)

    Hao, Hong; Kim, Douglas S; Klocke, Bernward; Johnson, Kory R; Cui, Kairong; Gotoh, Norimoto; Zang, Chongzhi; Gregorski, Janina; Gieser, Linn; Peng, Weiqun; Fann, Yang; Seifert, Martin; Zhao, Keji; Swaroop, Anand

    2012-01-01

    A stringent control of homeostasis is critical for functional maintenance and survival of neurons. In the mammalian retina, the basic motif leucine zipper transcription factor NRL determines rod versus cone photoreceptor cell fate and activates the expression of many rod-specific genes. Here, we report an integrated analysis of NRL-centered gene regulatory network by coupling chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-Seq) data from Illumina and ABI platforms with global expression profiling and in vivo knockdown studies. We identified approximately 300 direct NRL target genes. Of these, 22 NRL targets are associated with human retinal dystrophies, whereas 95 mapped to regions of as yet uncloned retinal disease loci. In silico analysis of NRL ChIP-Seq peak sequences revealed an enrichment of distinct sets of transcription factor binding sites. Specifically, we discovered that genes involved in photoreceptor function include binding sites for both NRL and homeodomain protein CRX. Evaluation of 26 ChIP-Seq regions validated their enhancer functions in reporter assays. In vivo knockdown of 16 NRL target genes resulted in death or abnormal morphology of rod photoreceptors, suggesting their importance in maintaining retinal function. We also identified histone demethylase Kdm5b as a novel secondary node in NRL transcriptional hierarchy. Exon array analysis of flow-sorted photoreceptors in which Kdm5b was knocked down by shRNA indicated its role in regulating rod-expressed genes. Our studies identify candidate genes for retinal dystrophies, define cis-regulatory module(s) for photoreceptor-expressed genes and provide a framework for decoding transcriptional regulatory networks that dictate rod homeostasis.

  8. Transcriptional regulation of rod photoreceptor homeostasis revealed by in vivo NRL targetome analysis.

    Directory of Open Access Journals (Sweden)

    Hong Hao

    Full Text Available A stringent control of homeostasis is critical for functional maintenance and survival of neurons. In the mammalian retina, the basic motif leucine zipper transcription factor NRL determines rod versus cone photoreceptor cell fate and activates the expression of many rod-specific genes. Here, we report an integrated analysis of NRL-centered gene regulatory network by coupling chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-Seq data from Illumina and ABI platforms with global expression profiling and in vivo knockdown studies. We identified approximately 300 direct NRL target genes. Of these, 22 NRL targets are associated with human retinal dystrophies, whereas 95 mapped to regions of as yet uncloned retinal disease loci. In silico analysis of NRL ChIP-Seq peak sequences revealed an enrichment of distinct sets of transcription factor binding sites. Specifically, we discovered that genes involved in photoreceptor function include binding sites for both NRL and homeodomain protein CRX. Evaluation of 26 ChIP-Seq regions validated their enhancer functions in reporter assays. In vivo knockdown of 16 NRL target genes resulted in death or abnormal morphology of rod photoreceptors, suggesting their importance in maintaining retinal function. We also identified histone demethylase Kdm5b as a novel secondary node in NRL transcriptional hierarchy. Exon array analysis of flow-sorted photoreceptors in which Kdm5b was knocked down by shRNA indicated its role in regulating rod-expressed genes. Our studies identify candidate genes for retinal dystrophies, define cis-regulatory module(s for photoreceptor-expressed genes and provide a framework for decoding transcriptional regulatory networks that dictate rod homeostasis.

  9. Unidirectional photoreceptor-to-Muller glia coupling and unique K+ channel expression in Caiman retina.

    Directory of Open Access Journals (Sweden)

    Astrid Zayas-Santiago

    Full Text Available BACKGROUND: Müller cells, the principal glial cells of the vertebrate retina, are fundamental for the maintenance and function of neuronal cells. In most vertebrates, including humans, Müller cells abundantly express Kir4.1 inwardly rectifying potassium channels responsible for hyperpolarized membrane potential and for various vital functions such as potassium buffering and glutamate clearance; inter-species differences in Kir4.1 expression were, however, observed. Localization and function of potassium channels in Müller cells from the retina of crocodiles remain, hitherto, unknown. METHODS: We studied retinae of the Spectacled caiman (Caiman crocodilus fuscus, endowed with both diurnal and nocturnal vision, by (i immunohistochemistry, (ii whole-cell voltage-clamp, and (iii fluorescent dye tracing to investigate K+ channel distribution and glia-to-neuron communications. RESULTS: Immunohistochemistry revealed that caiman Müller cells, similarly to other vertebrates, express vimentin, GFAP, S100β, and glutamine synthetase. In contrast, Kir4.1 channel protein was not found in Müller cells but was localized in photoreceptor cells. Instead, 2P-domain TASK-1 channels were expressed in Müller cells. Electrophysiological properties of enzymatically dissociated Müller cells without photoreceptors and isolated Müller cells with adhering photoreceptors were significantly different. This suggests ion coupling between Müller cells and photoreceptors in the caiman retina. Sulforhodamine-B injected into cones permeated to adhering Müller cells thus revealing a uni-directional dye coupling. CONCLUSION: Our data indicate that caiman Müller glial cells are unique among vertebrates studied so far by predominantly expressing TASK-1 rather than Kir4.1 K+ channels and by bi-directional ion and uni-directional dye coupling to photoreceptor cells. This coupling may play an important role in specific glia-neuron signaling pathways and in a new type of K

  10. G-quartet oligonucleotide mediated delivery of proteins into photoreceptors and retinal pigment epithelium via intravitreal injection.

    Science.gov (United States)

    Leaderer, Derek; Cashman, Siobhan M; Kumar-Singh, Rajendra

    2016-04-01

    There is currently no available method to efficiently deliver proteins across the plasma membrane of photoreceptor or retinal pigment epithelium (RPE) cells in vivo. Thus, current clinical application of recombinant proteins in ophthalmology is limited to the use of proteins that perform their biological function extracellularly. The ability to traverse biological membranes would enable the mobilization of a significantly larger number of proteins with previously well characterized properties. Nucleolin is abundantly present on the surface of rapidly dividing cells including cancer cells. Surprisingly, nucleolin is also present on the surface of photoreceptor cell bodies. Here we investigated whether nucleolin can be utilized as a gateway for the delivery of proteins into retinal cells following intravitreal injection. AS1411 is a G-quartet aptamer capable of targeting nucleolin. Subsequent to intravitreal injection, fluorescently labeled AS1411 localized to various retinal cell types including the photoreceptors and RPE. AS1411 linked to streptavidin (a ∼50 kDa protein) via a biotin bridge enabled the uptake of Streptavidin into photoreceptors and RPE. AS1411-Streptavidin conjugate applied topically to the cornea allowed for uptake of the conjugate into the nucleus and cytoplasm of corneal endothelial cells. Clinical relevance of AS1411 as a delivery vehicle was strongly indicated by demonstration of the presence of cell surface nucleolin on the photoreceptors, inner neurons and ganglion cells of human retina. These data support exploration of AS1411 as a means of delivering therapeutic proteins to diseased retina.

  11. Highly stable three-band white light from an InGaN-based blue light-emitting diode chip precoated with (oxy)nitride green/red phosphors

    Science.gov (United States)

    Yang, Chih-Chieh; Lin, Chih-Min; Chen, Yi-Jung; Wu, Yi-Tsuo; Chuang, Shih-Ren; Liu, Ru-Shi; Hu, Shu-Fen

    2007-03-01

    A three-band white light-emitting diode (LED) was fabricated using an InGaN-based blue LED chip that emits 455nm blue light, and green phosphor SrSi2O2N2:Eu and red phosphor CaSiN2:Ce that emit 538nm green and 642nm red emissions, respectively, when excited by the 455nm blue light. The luminous efficacy of this white LED is about 30lm /W at a dc of 20mA. With increasing dc from 5.0to60mA, both the coordinates x and y of the white LED tend to be the same, and consequently the Tc is the same and the Ra increases to 92.2.

  12. C-opsin expressing photoreceptors in echinoderms.

    Science.gov (United States)

    Ullrich-Lüter, Esther M; D'Aniello, Salvatore; Arnone, Maria I

    2013-07-01

    Today's progress in molecular analysis and, in particular, the increased availability of genome sequences have enabled us to investigate photoreceptor cells (PRCs) in organisms that were formerly inaccessible to experimental manipulation. Our studies of marine non-chordate deuterostomes thus aim to bridge a gap of knowledge regarding the evolution of deuterostome PRCs prior to the emergence of vertebrates' eyes. In this contribution, we will show evidence for expression of a c-opsin photopigment, which, according to our phylogenetic analysis, is closely related to an assemblage of chordate visual c-opsins. An antibody raised against sea urchins' c-opsin protein (Sp-Opsin1) recognizes epitopes in a variety of tissues of different echinoderms. While in sea urchins this c-opsin is expressed in locomotory and buccal tube feet, spines, pedicellaria, and epidermis, in brittlestars and starfish we found the immuno-reaction to be located exclusively in cells within the animals' spines. Structural characteristics of these c-opsin+ PRC types include the close vicinity/connection to nerve strands and a, so far unexplored, conspicuous association with the animals' calcite skeleton, which previously has been hypothesized to play a role in echinoderm photobiology. These features are discussed within the context of the evolution of photoreceptors in echinoderms and in deuterostomes generally.

  13. Blue Light-excited Light-Oxygen-Voltage-sensing Domain 2 (LOV2) Triggers a Rearrangement of the Kinase Domain to Induce Phosphorylation Activity in Arabidopsis Phototropin1.

    Science.gov (United States)

    Oide, Mao; Okajima, Koji; Kashojiya, Sachiko; Takayama, Yuki; Oroguchi, Tomotaka; Hikima, Takaaki; Yamamoto, Masaki; Nakasako, Masayoshi

    2016-09-16

    Phototropin1 is a blue light (BL) receptor in plants and shows BL-dependent kinase activation. The BL-excited light-oxygen-voltage-sensing domain 2 (LOV2) is primarily responsible for the activation of the kinase domain; however, the molecular mechanism by which conformational changes in LOV2 are transmitted to the kinase domain remains unclear. Here, we investigated BL-induced structural changes of a minimum functional fragment of Arabidopsis phototropin1 composed of LOV2, the kinase domain, and a linker connecting the two domains using small-angle x-ray scattering (SAXS). The fragment existed as a dimer and displayed photoreversible SAXS changes reflected in the radii of gyration of 42.9 Å in the dark and 48.8 Å under BL irradiation. In the dark, the molecular shape reconstructed from the SAXS profiles appeared as two bean-shaped lobes in a twisted arrangement that was 170 Å long, 80 Å wide, and 50 Å thick. The molecular shape under BL became slightly elongated from that in the dark. By fitting the crystal structure of the LOV2 dimer and a homology model of the kinase domain to their inferred shapes, the BL-dependent change could be interpreted as the positional shift in the kinase domain relative to that of the LOV2 dimer. In addition, we found that lysine 475, a functionally important residue, in the N-terminal region of LOV2 plays a critical role in transmitting the structural changes in LOV2 to the kinase domain. The interface between the domains is critical for signaling, suitably changing the structure to activate the kinase in response to conformational changes in the adjoining LOV2.

  14. The Comparison of the Efficacy of Blue Light-Emitting Diode Light and 980-nm Low-Level Laser Light on Bone Regeneration.

    Science.gov (United States)

    Dereci, Ömür; Sindel, Alper; Serap Toru, Havva; Yüce, Esra; Ay, Sinan; Tozoğlu, Sinan

    2016-11-01

    The aim of this study is to histologically compare effects of blue light-emitting diode (LED) light (400-490 nm) and Ga-Al-As low-level diode laser light (980 nm) on bone regeneration of calvarial critical-sized defects in rats. Thirty Wistar Albino rats were included in the study. The experimental groups were as follows: blue LED light (400-490 nm) group (LED); 980-nm low-level laser light group (LL); and no-treatment, control group (CL). A critical-sized defect of 8 mm was formed on calvaria of rats. Each animal was sacrificed 21 days after defect formation. Calvarias of all rats were dissected and fixated for histological examination. Histomorphometric measurements of total horizontal length of the newly produced bone tissue, total vertical length of the newly produced bone tissue, and diameter of the newly produced longest bone trabecula were performed with a computer program in micrometers. There was a statistically significant increase in the total horizontal length and total vertical length in LL and LED groups compared to that in the CL group (P  0.05). A statistically significant difference was observed in the longest bone trabecula and LL groups compared to that in CL (P  0.05). In conclusion, blue LED light significantly enhances bone regeneration in critical-sized defects when compared with CL group, but does not have a statistically significant effect on bone regeneration when compared with 980-nm low-level laser light.

  15. Effects of Blue Light Emitting Diode Irradiation On the Proliferation, Apoptosis and Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells.

    Science.gov (United States)

    Yuan, Ye; Yan, Gege; Gong, Rui; Zhang, Lai; Liu, Tianyi; Feng, Chao; Du, Weijie; Wang, Ying; Yang, Fan; Li, Yuan; Guo, Shuyuan; Ding, Fengzhi; Ma, Wenya; Idiiatullina, Elina; Pavlov, Valentin; Han, Zhenbo; Cai, Benzhi; Yang, Lei

    2017-08-30

    Blue light emitting diodes (LEDs) have been proven to affect the growth of several types of cells. The effects of blue LEDs have not been tested on bone marrow-derived mesenchymal stem cells (BMSCs), which are important for cell-based therapy in various medical fields. Therefore, the aim of this study was to determine the effects of blue LED on the proliferation, apoptosis and osteogenic differentiation of BMSCs. BMSCs were irradiated with a blue LED light at 470 nm for 1 min, 5 min, 10 min, 30 min and 60 min or not irradiated. Cell proliferation was measured by performing cell counting and EdU staining assays. Cell apoptosis was detected by TUNEL staining. Osteogenic differentiation was evaluated by ALP and ARS staining. DCFH-DA staining and γ-H2A.X immunostaining were used to measure intracellular levels of ROS production and DNA damage. Both cell counting and EdU staining assays showed that cell proliferation of BMSCs was significantly reduced upon blue LED irradiation. Furthermore, treatment of BMSCs with LED irradiation was followed by a remarkable increase in apoptosis, indicating that blue LED light induced toxic effects on BMSCs. Likewise, BMSC osteogenic differentiation was inhibited after exposure to blue LED irradiation. Further, blue LED irradiation was followed by the accumulation of ROS production and DNA damage. Taken together, our study demonstrated that blue LED light inhibited cell proliferation, inhibited osteogenic differentiation, and induced apoptosis in BMSCs, which are associated with increased ROS production and DNA damage. These findings may provide important insights for the application of LEDs in future BMSC-based therapies. © 2017 The Author(s). Published by S. Karger AG, Basel.

  16. Effect of red and blue light emitting diodes "CRB-LED" on in vitro organogenesis of date palm (Phoenix dactylifera L.) cv. Alshakr.

    Science.gov (United States)

    Al-Mayahi, Ahmed Madi Waheed

    2016-10-01

    The objective of the present study is to determine the effect of light source on enhancement of shoot multiplication, phytochemicals, as well as, antioxidant enzyme activities of in vitro cultures of date palm cv. Alshakr. In vitro-grown buds were cultured on Murashige and Skoog (MS) medium and incubated under a conventional white fluorescent light (control), and combinations of red + blue light emitting diode (18:2) (CRB-LED). Results revealed that the treatment of CRB-LED showed a significant increase in the number of shoots compared with the white florescent light. Total soluble carbohydrate "TSCH" (7.10 mg g(-1) DW.), starch (1.63 mg g(-1) DW.) and free amino acids (2.90 mg g(-1) DW.) were significantly higher in CRB-LED (p < 0.05). Additionally, CRB-LED induced a higher peroxidase activity (25.50 U ml(-1)) compared with the white fluorescent light treatment (19.74 U ml(-1)) as control treatment. Potassium, magnesium and sodium contents in (3.62, 13.99 and 2.76 mg g(-1) DW.) were increased in in vitro shoots under CRB-LED treatment in comparison with fluorescent light (p < 0.05). Protein profile showed the appearance of newly bands with the molecular weight of 38 and 60 kDa at the treatment CRB-LED compared with control treatment. Our results demonstrate the positive effects of CRB-LED light during the course of date palm tissue cultures.

  17. Influence of laser lift-off on optical and structural properties of InGaN/GaN vertical blue light emitting diodes

    Directory of Open Access Journals (Sweden)

    M. H. Doan

    2012-06-01

    Full Text Available The influences of the laser lift-off (LLO process on the InGaN/GaN blue light emitting diode (LED structures, grown on sapphire substrates by low-pressure metalorganic chemical vapor deposition, have been comprehensively investigated. The vertical LED structures on Cu carriers are fabricated using electroplating, LLO, and inductively coupled plasma etching processes sequentially. A detailed study is performed on the variation of defect concentration and optical properties, before and after the LLO process, employing high-resolution transmission electron microscopy (HRTEM, scanning electron microscopy (SEM observations, cathodoluminescence (CL, photoluminescence (PL, and high-resolution X-ray diffraction (HRXRD measurements. The SEM observations on the distribution of dislocations after the LLO show well that even the GaN layer near to the multiple quantum wells (MQWs is damaged. The CL measurements reveal that the peak energy of the InGaN/GaN MQW emission exhibits a blue-shift after the LLO process in addition to a reduced intensity. These behaviors are attributed to a diffusion of indium through the defects created by the LLO and creation of non-radiative recombination centers. The observed phenomena thus suggest that the MQWs, the active region of the InGaN/GaN light emitting diodes, may be damaged by the LLO process when thickness of the GaN layer below the MQW is made to be 5 μm, a conventional thickness. The CL images on the boundary between the KrF irradiated and non-irradiated regions suggest that the propagation of the KrF laser beam and an accompanied recombination enhanced defect reaction, rather than the propagation of a thermal shock wave, are the main origin of the damage effects of the LLO process on the InGaN/GaN MQWs and the n-GaN layer as well.

  18. Intracellular localization of GBF proteins and blue light-induced import of GBF2 fusion proteins into the nucleus of cultured Arabidopsis and soybean cells.

    Science.gov (United States)

    Terzaghi, W B; Bertekap, R L; Cashmore, A R

    1997-05-01

    The G-box is an important regulatory element found in the promoters of many different genes. Four members of an Arabidopsis gene family encoding basic leucine zipper proteins (GBFs) which bind the G-box have previously been cloned. To study GBFs, a polyclonal antibody was raised against GBF1 expressed in bacteria. This antibody also recognized GBF2 and GBF3. Immunoblot analysis of nuclear and cytoplasmic fractions from Arabidopsis and soybean (SB-M) cell cultures indicated that over 90% of proteins detected with anti-GBF1 were cytoplasmic. Electrophoretic mobility shift assays indicated that over 90% of G-box binding activity was cytoplasmic. DNA affinity chromatography demonstrated that each protein detected with anti-GBF1 specifically bound the G-box. To study individual GBFs, DNA constructs fusing GBF1, GBF2 and GBF4 to GUS were made and assayed by transient expression in SB-M protoplasts. Of GUS:GBF1 proteins, 50-62% were localized in the cytoplasm under all conditions tested, while 97% of GUS:GBF4 was localized in the nucleus. By contrast, whereas about 50% of GUS:GBF2 was found in the cytoplasm of dark-grown cells, over 80% of this protein was found in the nucleus in cells cultured under blue light. Deletion analysis of GBF1 identified a region between amino acids 112 and 164 apparently required for cytoplasmic retention. These results suggest the intriguing possibility that limitation of nuclear access may be an important control on GBF activity. In particular, GBF2 is apparently specifically imported into the nucleus in response to light.

  19. 蓝光诱导蛹虫草虫草素含量和分生孢子数的变化%Changes of Cordycepin Content and Conidia Amount of Cordyceps militaris by Blue Light Induction

    Institute of Scientific and Technical Information of China (English)

    金华燕; 沈俊良; 付鸣佳; 高雅; 黄妮娜

    2013-01-01

    [目的]研究蓝光对蛹虫草菌丝体中虫草素含量和分生孢子量的影响.[方法]以蛹虫草为材料,在不同的蓝光照射时间取样,以检测菌丝体中虫草素的含量,并计数蛹虫草分生孢子的产生量.[结果]蛹虫草受蓝光照射后,其虫草素的产生受到了一定的抑制,同时虫草素含量的变化也有一定的波动性;在相同的时间点,受蓝光照射的蛹虫草分生孢子数量比黑暗时的分生孢子数量要多,同时在一定时间范围内分生孢子数均呈上升趋势.[结论]该研究为系统性的研究蓝光对蛹虫草的影响奠定了基础.%[Objective]The aim was to study the effects of blue light on cordycepin content and conidia amount of Cordyceps militaris mycelium. [Method] The cordycepin content of mycelium and amount of Cordyceps milUaris conidia was detected at different blue light irradiation times by using Cordyceps militaris as materials. [ Result] The production of cordycepin was inhibited to a certain degree and the changes of cordycepin content also had a certain fluctuation after the Cordyceps militaris was irradiated by blue light; the amount of conidia of Cordyceps militaris irradiated by blue light was more than its number in the darkness at the same sampling time, and the number of conidia had been on an upward trend during a definite period of time at the same time. [Conclusion] This study provided foundation for the system researches on the effects of blue light on Cordyceps milUaris.

  20. Method to Remove Photoreceptors from Wholemount Retina in vitro.

    Science.gov (United States)

    Walston, Steven T; Chang, Yao-Chuan; Weiland, James D; Chow, Robert H

    2017-08-30

    Patch clamp recordings of neurons in the inner nuclear layer of the retina are difficult to conduct in a wholemount retina preparation because surrounding neurons block the path of the patch pipette. Vertical slice preparations or dissociated retina cell cultures provide access to bipolar cells at the cost of severing lateral connection between neurons. We have developed a technique to remove photoreceptors from the rodent retina that exposes inner nuclear layer neurons, allowing access for patch clamp recording. Repeated application and removal of filter paper to the photoreceptor side of an isolated retina effectively and efficiently removes photoreceptor cells and, in degenerate retina, hypertrophied Müller cell endfeet. Live-dead assays applied to neurons remaining after photoreceptor removal demonstrated mostly viable cells. Patch clamp recordings from bipolar cells reveal responses similar to those recorded in traditional slice and dissociated cell preparations. An advantage of the photoreceptor peel technique is that it exposes inner retinal neurons in a wholemount retina preparation for investigation of signal processing. A disadvantage is that photoreceptor removal alters input to remaining retinal neurons. The technique may be useful for investigations of extracellular electrical stimulation, photoreceptor DNA analysis, and non-pharmacological removal of light input. Copyright © 2017, Journal of Neurophysiology.

  1. Functional photoreceptor loss revealed with adaptive optics: an alternate cause of color blindness.

    Science.gov (United States)

    Carroll, Joseph; Neitz, Maureen; Hofer, Heidi; Neitz, Jay; Williams, David R

    2004-06-01

    There is enormous variation in the X-linked L/M (long/middle wavelength sensitive) gene array underlying "normal" color vision in humans. This variability has been shown to underlie individual variation in color matching behavior. Recently, red-green color blindness has also been shown to be associated with distinctly different genotypes. This has opened the possibility that there may be important phenotypic differences within classically defined groups of color blind individuals. Here, adaptive optics retinal imaging has revealed a mechanism for producing dichromatic color vision in which the expression of a mutant cone photopigment gene leads to the loss of the entire corresponding class of cone photoreceptor cells. Previously, the theory that common forms of inherited color blindness could be caused by the loss of photoreceptor cells had been discounted. We confirm that remarkably, this loss of one-third of the cones does not impair any aspect of vision other than color.

  2. What determines the relationship between color naming, unique hues, and sensory singularities: Illuminations, surfaces, or photoreceptors?

    Science.gov (United States)

    Witzel, Christoph; Cinotti, François; O'Regan, J Kevin

    2015-01-01

    The relationship between the sensory signal of the photoreceptors on one hand and color appearance and language on the other hand is completely unclear. A recent finding established a surprisingly accurate correlation between focal colors, unique hues, and so-called singularities in the laws governing how sensory signals for different surfaces change across illuminations. This article examines how this correlation with singularities depends on reflectances, illuminants, and cone sensitivities. Results show that this correlation holds for a large range of illuminants and for a large range of sensors, including sensors that are fundamentally different from human photoreceptors. In contrast, the spectral characteristics of the reflectance spectra turned out to be the key factor that determines the correlation between focal colors, unique hues, and sensory singularities. These findings suggest that the origins of color appearance and color language may be found in particular characteristics of the reflectance spectra that correspond to focal colors and unique hues.

  3. Action spectra of zebrafish cone photoreceptors.

    Directory of Open Access Journals (Sweden)

    Duco Endeman

    Full Text Available Zebrafish is becoming an increasingly popular model in the field of visual neuroscience. Although the absorption spectra of its cone photopigments have been described, the cone action spectra were still unknown. In this study we report the action spectra of the four types of zebrafish cone photoreceptors, determined by measuring voltage responses upon light stimulation using whole cell patch clamp recordings. A generic template of photopigment absorption spectra was fit to the resulting action spectra in order to establish the maximum absorption wavelength, the A2-based photopigment contribution and the size of the β-wave of each cone-type. Although in general there is close correspondence between zebrafish cone action- and absorbance spectra, our data suggest that in the case of MWS- and LWS-cones there is appreciable contribution of A2-based photopigments and that the β-wave for these cones is smaller than expected based on the absorption spectra.

  4. Automatic cone photoreceptor segmentation using graph theory and dynamic programming.

    Science.gov (United States)

    Chiu, Stephanie J; Lokhnygina, Yuliya; Dubis, Adam M; Dubra, Alfredo; Carroll, Joseph; Izatt, Joseph A; Farsiu, Sina

    2013-06-01

    Geometrical analysis of the photoreceptor mosaic can reveal subclinical ocular pathologies. In this paper, we describe a fully automatic algorithm to identify and segment photoreceptors in adaptive optics ophthalmoscope images of the photoreceptor mosaic. This method is an extension of our previously described closed contour segmentation framework based on graph theory and dynamic programming (GTDP). We validated the performance of the proposed algorithm by comparing it to the state-of-the-art technique on a large data set consisting of over 200,000 cones and posted the results online. We found that the GTDP method achieved a higher detection rate, decreasing the cone miss rate by over a factor of five.

  5. Nitric Oxide Blocks Blue Light-Induced K+ Influx by Elevating the Cytosolic Ca2+ Concentration in Vicia faba L.Guard Cells

    Institute of Scientific and Technical Information of China (English)

    Xiang Zhao; Yuan-Yuan Li; Hui-Li Xiao; Chang-Shui Xu; Xiao Zhang

    2013-01-01

    Ca2+ plays a pivotal role in nitric oxide (NO)-promoted stomatal closure.However,the function of Ca2+ in NO inhibition of blue light (BL)-induced stomatal opening remains largely unknown.Here,we analyzed the role of Ca2+ in the crosstalk between BL and NO signaling in Vicia faba L.guard cells.Extracellular Ca2+ modulated the BL-induced stomatal opening in a dose-dependent manner,and an application of 5 μM Ca2+ in the pipette solution significantly inhibited BL-activated K+ influx.Sodium nitroprusside (SNP),a NO donor,showed little effect on BL-induced K+ influx and stomatal opening response in the absence of extracellular Ca2+,but K+ influx and stomatal opening were inhibited by SNP when Ca2+ was added to the bath solution.Interestingly,although both SNP and BL could activate the plasma membrane Ca2+ channels and induce the rise of cytosolic Ca2+,the change in levels of Ca2+ channel activity and cytosolic Ca2+ concentration were different between SNP and BL treatments.SNP at 100 μM obviously activated the plasma membrane Ca2+ channels and induced cytosolic Ca2+ rise by 102.4%.In contrast,a BL pulse (100 μmol/m2 per s for 30 s) slightly activated the Ca2+ channels and resulted in a Ca2+ rise of only 20.8%.Consistently,cytosolic Ca2+ promoted K+ influx at 0.5 μM or below,and significantly inhibited K+ influx at 5 μM or above.Taken together,our findings indicate that Ca2+ plays dual and distinctive roles in the crosstalk between BL and NO signaling in guard cells,mediating both the BL-induced K+ influx as an activator at a lower concentration and the NO-blocked K+ influx as an inhibitor at a higher concentration.

  6. Bright light in elderly subjects with nonseasonal major depressive disorder: a double blind randomised clinical trial using early morning bright blue light comparing dim red light treatment

    Directory of Open Access Journals (Sweden)

    van Someren Eus JW

    2008-07-01

    Full Text Available Abstract Background Depression frequently occurs in the elderly. Its cause is largely unknown, but several studies point to disturbances of biological rhythmicity. In both normal aging, and depression, the functioning of the suprachiasmatic nucleus (SCN is impaired, as evidenced by an increased prevalence of day-night rhythm perturbations, such as sleeping disorders. Moreover, the inhibitory SCN neurons on the hypothalamus-pituitary adrenocortical axis (HPA-axis have decreased activity and HPA-activity is enhanced, when compared to non-depressed elderly. Using bright light therapy (BLT the SCN can be stimulated. In addition, the beneficial effects of BLT on seasonal depression are well accepted. BLT is a potentially safe, nonexpensive and well accepted treatment option. But the current literature on BLT for depression is inconclusive. Methods/Design This study aims to show whether BLT can reduce non-seasonal major depression in elderly patients. Randomized double blind placebo controlled trial in 126 subjects of 60 years and older with a diagnosis of major depressive disorder (MDD, DSM-IV/SCID-I. Subjects are recruited through referrals of psychiatric outpatient clinics and from case finding from databases of general practitioners and old-people homes in the Amsterdam region. After inclusion subjects are randomly allocated to the active (bright blue light vs. placebo (dim red light condition using two Philips Bright Light Energy boxes type HF 3304 per subject, from which the light bulbs have been covered with bright blue- or dim red light- permitting filters. Patients will be stratified by use of antidepressants. Prior to treatment a one-week period without light treatment will be used. At three time points several endocrinological, psychophysiological, psychometrically, neuropsychological measures are performed: just before the start of light therapy, after completion of three weeks therapy period, and three weeks thereafter. Discussion If BLT

  7. Light Modulates Metabolic Pathways and Other Novel Physiological Traits in the Human Pathogen Acinetobacter baumannii.

    Science.gov (United States)

    Müller, Gabriela L; Tuttobene, Marisel; Altilio, Matías; Martínez Amezaga, Maitena; Nguyen, Meaghan; Cribb, Pamela; Cybulski, Larisa E; Ramírez, María Soledad; Altabe, Silvia; Mussi, María Alejandra

    2017-05-15

    Light sensing in chemotrophic bacteria has been relatively recently ascertained. In the human pathogen Acinetobacter baumannii, light modulates motility, biofilm formation, and virulence through the blue-light-sensing-using flavin (BLUF) photoreceptor BlsA. In addition, light can induce a reduction in susceptibility to certain antibiotics, such as minocycline and tigecycline, in a photoreceptor-independent manner. In this work, we identified new traits whose expression levels are modulated by light in this pathogen, which comprise not only important determinants related to pathogenicity and antibiotic resistance but also metabolic pathways, which represents a novel concept for chemotrophic bacteria. Indeed, the phenylacetic acid catabolic pathway and trehalose biosynthesis were modulated by light, responses that completely depend on BlsA. We further show that tolerance to some antibiotics and modulation of antioxidant enzyme levels are also influenced by light, likely contributing to bacterial persistence in adverse environments. Also, we present evidence indicating that surfactant production is modulated by light. Finally, the expression of whole pathways and gene clusters, such as genes involved in lipid metabolism and genes encoding components of the type VI secretion system, as well as efflux pumps related to antibiotic resistance, was differentially induced by light. Overall, our results indicate that light modulates global features of the A. baumannii lifestyle.IMPORTANCE The discovery that nonphototrophic bacteria respond to light constituted a novel concept in microbiology. In this context, we demonstrated that light could modulate aspects related to bacterial virulence, persistence, and resistance to antibiotics in the human pathogen Acinetobacter baumannii In this work, we present the novel finding that light directly regulates metabolism in this chemotrophic bacterium. Insights into the mechanism show the involvement of the photoreceptor BlsA. In

  8. Adaptive potentiation in rod photoreceptors after light exposure

    OpenAIRE

    McKeown, Alex S; Kraft, Timothy W.

    2014-01-01

    Photoreceptors adapt to changes in illumination by altering transduction kinetics and sensitivity, thereby extending their working range. We describe a previously unknown form of rod photoreceptor adaptation in wild-type (WT) mice that manifests as a potentiation of the light response after periods of conditioning light exposure. We characterize the stimulus conditions that evoke this graded hypersensitivity and examine the molecular mechanisms of adaptation underlying the phenomenon. After e...

  9. Adaptive Optics Reveals Photoreceptor Abnormalities in Diabetic Macular Ischemia

    Science.gov (United States)

    Nesper, Peter L.; Scarinci, Fabio

    2017-01-01

    Diabetic macular ischemia (DMI) is a phenotype of diabetic retinopathy (DR) associated with chronic hypoxia of retinal tissue. The goal of this prospective observational study was to report evidence of photoreceptor abnormalities using adaptive optics scanning laser ophthalmoscopy (AOSLO) in eyes with DR in the setting of deep capillary plexus (DCP) non-perfusion. Eleven eyes from 11 patients (6 women, age 31–68), diagnosed with DR without macular edema, underwent optical coherence tomography angiography (OCTA) and AOSLO imaging. One patient without OCTA imaging underwent fluorescein angiography to characterize the enlargement of the foveal avascular zone. The parameters studied included photoreceptor heterogeneity packing index (HPi) on AOSLO, as well as DCP non-perfusion and vessel density on OCTA. Using AOSLO, OCTA and spectral domain (SD)-OCT, we observed that photoreceptor abnormalities on AOSLO and SD-OCT were found in eyes with non-perfusion of the DCP on OCTA. All eight eyes with DCP non-flow on OCTA showed photoreceptor abnormalities on AOSLO. Six of the eight eyes also had outer retinal abnormalities on SD-OCT. Three eyes with DR and robust capillary perfusion of the DCP had normal photoreceptors on SD-OCT and AOSLO. Compared to eyes with DR without DCP non-flow, the eight eyes with DCP non-flow had significantly lower HPi (P = 0.013) and parafoveal DCP vessel density (P = 0.016). We found a significant correlation between cone HPi and parafoveal DCP vessel density (r = 0.681, P = 0.030). Using a novel approach with AOSLO and OCTA, this study shows an association between capillary non-perfusion of the DCP and abnormalities in the photoreceptor layer in eyes with DR. This observation is important in confirming the significant contribution of the DCP to oxygen requirements of photoreceptors in DMI, while highlighting the ability of AOSLO to detect subtle photoreceptor changes not always visible on SD-OCT. PMID:28068435

  10. Contribution of photoreceptor subtypes to spectral wavelength preference in Drosophila.

    Science.gov (United States)

    Yamaguchi, Satoko; Desplan, Claude; Heisenberg, Martin

    2010-03-23

    The visual systems of most species contain photoreceptors with distinct spectral sensitivities that allow animals to distinguish lights by their spectral composition. In Drosophila, photoreceptors R1-R6 have the same spectral sensitivity throughout the eye and are responsible for motion detection. In contrast, photoreceptors R7 and R8 exhibit heterogeneity and are important for color vision. We investigated how photoreceptor types contribute to the attractiveness of light by blocking the function of certain subsets and by measuring differential phototaxis between spectrally different lights. In a "UV vs. blue" choice, flies with only R1-R6, as well as flies with only R7/R8 photoreceptors, preferred blue, suggesting a nonadditive interaction between the two major subsystems. Flies defective for UV-sensitive R7 function preferred blue, whereas flies defective for either type of R8 (blue- or green-sensitive) preferred UV. In a "blue vs. green" choice, flies defective for R8 (blue) preferred green, whereas those defective for R8 (green) preferred blue. Involvement of all photoreceptors [R1-R6, R7, R8 (blue), R8 (green)] distinguishes phototaxis from motion detection that is mediated exclusively by R1-R6.

  11. Visual ecology and potassium conductances of insect photoreceptors.

    Science.gov (United States)

    Frolov, Roman; Immonen, Esa-Ville; Weckström, Matti

    2016-04-01

    Voltage-activated potassium channels (Kv channels) in the microvillar photoreceptors of arthropods are responsible for repolarization and regulation of photoreceptor signaling bandwidth. On the basis of analyzing Kv channels in dipteran flies, it was suggested that diurnal, rapidly flying insects predominantly express sustained K(+) conductances, whereas crepuscular and nocturnally active animals exhibit strongly inactivating Kv conductances. The latter was suggested to function for minimizing cellular energy consumption. In this study we further explore the evolutionary adaptations of the photoreceptor channelome to visual ecology and behavior by comparing K(+) conductances in 15 phylogenetically diverse insects, using patch-clamp recordings from dissociated ommatidia. We show that rapid diurnal flyers such as the blowfly (Calliphora vicina) and the honeybee (Apis mellifera) express relatively large noninactivating Kv conductances, conforming to the earlier hypothesis in Diptera. Nocturnal and/or slow-moving species do not in general exhibit stronger Kv conductance inactivation in the physiological membrane voltage range, but the photoreceptors in species that are known to rely more on vision behaviorally had higher densities of sustained Kv conductances than photoreceptors of less visually guided species. No statistically significant trends related to visual performance could be identified for the rapidly inactivating Kv conductances. Counterintuitively, strong negative correlations were observed between photoreceptor capacitance and specific membrane conductance for both sustained and inactivating fractions of Kv conductance, suggesting insignificant evolutionary pressure to offset negative effects of high capacitance on membrane filtering with increased conductance.

  12. 蓝光对痤疮患者的疗效及对糠秕马拉色菌的影响%Effects of blue light therapy on acne and Malassezia furfur

    Institute of Scientific and Technical Information of China (English)

    穆艳蕾; 杨蓉娅; 王文岭; 樊昕; 徐阳; 王聪敏; 张洁

    2009-01-01

    目的 观察波长407~420 nm蓝光对痤疮患者的疗效,对面部皮肤皮脂溢出率及糠秕马拉色菌的影响.方法 对20例痤疮患者蓝光治疗前后行电子显微成像观察,评价靶疹的表皮层及真皮浅层变化;应用Looking bill及Cunliffe改良测定法进行皮脂溢出率测定;应用蓝光对培养的糠秕马拉色菌进行照射,观察照光前后菌落的数量及形态变化.结果 20例痤疮患者蓝光治疗后靶疹明显消退,其表皮层及真皮浅层损伤减轻;皮脂溢出率较治疗前显著减少(P<0.01);在0.5 ml细胞数为5×10~6/ml的糠秕马拉色菌菌液中,菌落数量、直径与光照时间成反比,蓝光光照时间大于3 min 30 s时,平吼内无菌落生长.结论 蓝光对痤疮有很好的治疗效果:能修复深至真皮层的皮肤损伤,抑制皮脂分泌,对糠秕马拉色菌有杀菌作用.%Objective To investigate the effects of blue light (407 to 420 nm) therapy on acne, facial se-bum excretion rate and the growth of Malassezia furfur isolated from ache lesions. Methods Twenty cases of ac-ne patients were treated with the blue light system. Before and after the treatments, electronic microscopy were used to assess the change of the target acne in epidermis and dermis. Looking bill and Cunliffe' s technique was used to test the sebum excretion rate (SER). Selected bacterial strains of Malassezia furfur were radiated with the blue light. The morphology and number of colony formation units (CFUs) of the bacteria were observed before and after the irradiation. Results Twenty cases of ache patients' target aches fade away remarkably and the injuries in the epidermis and dermis were alleviated. The SER was decreased significantly (P <0.01) after the treatment of blue light. There was no coenobium of Malassezia furfur when the time of blue light irradiation exceeded 3.5 min. The number and diameter of the coenobium were in inverse proportion to the irradiation time.Conclusion The blue light can

  13. The short-lived signaling state of the photoactive yellow protein photoreceptor revealed by combined structural probes.

    Science.gov (United States)

    Ramachandran, Pradeep L; Lovett, Janet E; Carl, Patrick J; Cammarata, Marco; Lee, Jae Hyuk; Jung, Yang Ouk; Ihee, Hyotcherl; Timmel, Christiane R; van Thor, Jasper J

    2011-06-22

    The signaling state of the photoactive yellow protein (PYP) photoreceptor is transiently developed via isomerization of its blue-light-absorbing chromophore. The associated structural rearrangements have large amplitude but, due to its transient nature and chemical exchange reactions that complicate NMR detection, its accurate three-dimensional structure in solution has been elusive. Here we report on direct structural observation of the transient signaling state by combining double electron electron resonance spectroscopy (DEER), NMR, and time-resolved pump-probe X-ray solution scattering (TR-SAXS/WAXS). Measurement of distance distributions for doubly spin-labeled photoreceptor constructs using DEER spectroscopy suggests that the signaling state is well ordered and shows that interspin-label distances change reversibly up to 19 Å upon illumination. The SAXS/WAXS difference signal for the signaling state relative to the ground state indicates the transient formation of an ordered and rearranged conformation, which has an increased radius of gyration, an increased maximum dimension, and a reduced excluded volume. Dynamical annealing calculations using the DEER derived long-range distance restraints in combination with short-range distance information from (1)H-(15)N HSQC perturbation spectroscopy give strong indication for a rearrangement that places part of the N-terminal domain in contact with the exposed chromophore binding cleft while the terminal residues extend away from the core. Time-resolved global structural information from pump-probe TR-SAXS/WAXS data supports this conformation and allows subsequent structural refinement that includes the combined energy terms from DEER, NMR, and SAXS/WAXS together. The resulting ensemble simultaneously satisfies all restraints, and the inclusion of TR-SAXS/WAXS effectively reduces the uncertainty arising from the possible spin-label orientations. The observations are essentially compatible with reduced folding of the

  14. 红蓝光联合多西环素治疗寻常痤疮疗效观察%Observation of curative effect by red-blue light combined with doxycycline in the treatment of acne ;vulgaris

    Institute of Scientific and Technical Information of China (English)

    种树彬

    2015-01-01

    目的:观察红蓝光联合多西环素治疗寻常痤疮的临床疗效。方法120例寻常痤疮患者随机分为治疗组和对照组,各60例,治疗组采用红蓝光照射治疗,同时口服多西环素;对照组单独口服多西环素。对比两组疗效。结果治疗组总有效率为83.3%;对照组总有效率为61.7%,治疗组优于对照组(P<0.05)。结论红蓝光联合多西环素治疗寻常痤疮,疗效满意,值得临床推广应用。%Objective To observe clinical effect by red-blue light combined with doxycycline in the treatment of acne vulgaris. Methods A total of 120 acne vulgaris patients were randomly divided into treatment group and control group, with 60 cases in each group. The treatment group received red-blue light for radiation and oral administration of doxycycline. The control group received single doxycycline by oral administration. Their curative effects were compared. Results The treatment group had total effective rate as 83.3%, and the control group had that as 61.7%. It was better in the treatment group than the control group (P<0.05). Conclusion Implement of red-blue light combined with doxycycline in the treatment of acne vulgaris provides satisfactory effects, and this method is worthy of clinical promotion and application.

  15. Derivation of Traceable and Transplantable Photoreceptors from Mouse Embryonic Stem Cells

    Directory of Open Access Journals (Sweden)

    Sarah Decembrini

    2014-06-01

    Full Text Available Retinal degenerative diseases resulting in the loss of photoreceptors are one of the major causes of blindness. Photoreceptor replacement therapy is a promising treatment because the transplantation of retina-derived photoreceptors can be applied now to different murine retinopathies to restore visual function. To have an unlimited source of photoreceptors, we derived a transgenic embryonic stem cell (ESC line in which the Crx-GFP transgene is expressed in photoreceptors and assessed the capacity of a 3D culture protocol to produce integration-competent photoreceptors. This culture system allows the production of a large number of photoreceptors recapitulating the in vivo development. After transplantation, integrated cells showed the typical morphology of mature rods bearing external segments and ribbon synapses. We conclude that a 3D protocol coupled with ESCs provides a safe and renewable source of photoreceptors displaying a development and transplantation competence comparable to photoreceptors from age-matched retinas.

  16. cGMP production of patient-specific iPSCs and photoreceptor precursor cells to treat retinal degenerative blindness.

    Science.gov (United States)

    Wiley, Luke A; Burnight, Erin R; DeLuca, Adam P; Anfinson, Kristin R; Cranston, Cathryn M; Kaalberg, Emily E; Penticoff, Jessica A; Affatigato, Louisa M; Mullins, Robert F; Stone, Edwin M; Tucker, Budd A

    2016-07-29

    Immunologically-matched, induced pluripotent stem cell (iPSC)-derived photoreceptor precursor cells have the potential to restore vision to patients with retinal degenerative diseases like retinitis pigmentosa. The purpose of this study was to develop clinically-compatible methods for manufacturing photoreceptor precursor cells from adult skin in a non-profit cGMP environment. Biopsies were obtained from 35 adult patients with inherited retinal degeneration and fibroblast lines were established under ISO class 5 cGMP conditions. Patient-specific iPSCs were then generated, clonally expanded and validated. Post-mitotic photoreceptor precursor cells were generated using a stepwise cGMP-compliant 3D differentiation protocol. The recapitulation of the enhanced S-cone phenotype in retinal organoids generated from a patient with NR2E3 mutations demonstrated the fidelity of these protocols. Transplantation into immune compromised animals revealed no evidence of abnormal proliferation or tumor formation. These studies will enable clinical trials to test the safety and efficiency of patient-specific photoreceptor cell replacement in humans.

  17. Transplantation of Photoreceptor Precursors Isolated via a Cell Surface Biomarker Panel From Embryonic Stem Cell-Derived Self-Forming Retina.

    Science.gov (United States)

    Lakowski, Jorn; Gonzalez-Cordero, Anai; West, Emma L; Han, Ya-Ting; Welby, Emily; Naeem, Arifa; Blackford, Samuel J I; Bainbridge, James W B; Pearson, Rachael A; Ali, Robin R; Sowden, Jane C

    2015-08-01

    Loss of photoreceptors due to retinal degeneration is a major cause of untreatable blindness. Cell replacement therapy, using pluripotent stem cell-derived photoreceptor cells, may be a feasible future treatment. Achieving safe and effective cell replacement is critically dependent on the stringent selection and purification of optimal cells for transplantation. Previously, we demonstrated effective transplantation of post-mitotic photoreceptor precursor cells labelled by fluorescent reporter genes. As genetically labelled cells are not desirable for therapy, here we developed a surface biomarker cell selection strategy for application to complex pluripotent stem cell differentiation cultures. We show that a five cell surface biomarker panel CD73(+)CD24(+)CD133(+)CD47(+)CD15(-) facilitates the isolation of photoreceptor precursors from three-dimensional self-forming retina differentiated from mouse embryonic stem cells. Importantly, stem cell-derived cells isolated using the biomarker panel successfully integrate and mature into new rod photoreceptors in the adult mouse retinae after subretinal transplantation. Conversely, unsorted or negatively selected cells do not give rise to newly integrated rods after transplantation. The biomarker panel also removes detrimental proliferating cells prior to transplantation. Notably, we demonstrate how expression of the biomarker panel is conserved in the human retina and propose that a similar selection strategy will facilitate isolation of human transplantation-competent cells for therapeutic application.

  18. Biophysical mechanism of transient retinal phototropism in rod photoreceptors

    Science.gov (United States)

    Zhao, Xiaohui; Thapa, Damber; Wang, Benquan; Gai, Shaoyan; Yao, Xincheng

    2016-03-01

    Oblique light stimulation evoked transient retinal phototropism (TRP) has been recently detected in frog and mouse retinas. High resolution microscopy of freshly isolated retinas indicated that the TRP is predominated by rod photoreceptors. Comparative confocal microscopy and optical coherence tomography (OCT) revealed that the TRP predominantly occurred from the photoreceptor outer segment (OS). However, biophysical mechanism of rod OS change is still unknown. In this study, frog retinal slices, which open a cross section of retinal photoreceptor and other functional layers, were used to test the effect of light stimulation on rod OS. Near infrared light microscopy was employed to monitor photoreceptor changes in retinal slices stimulated by a rectangular-shaped visible light flash. Rapid rod OS length change was observed after the stimulation delivery. The magnitude and direction of the rod OS change varied with the position of the rods within the stimulated area. In the center of stimulated region the length of the rod OS shrunk, while in the peripheral region the rod OS tip swung towards center region in the plane perpendicular to the incident stimulus light. Our experimental result and theoretical analysis suggest that the observed TRP may reflect unbalanced disc-shape change due to localized pigment bleaching. Further investigation is required to understand biochemical mechanism of the observed rod OS kinetics. Better study of the TRP may provide a noninvasive biomarker to enable early detection of age-related macular degeneration (AMD) and other diseases that are known to produce retinal photoreceptor dysfunctions.

  19. Cloning and characterization of mr-s, a novel SAM domain protein, predominantly expressed in retinal photoreceptor cells

    Directory of Open Access Journals (Sweden)

    Koike Chieko

    2006-03-01

    Full Text Available Abstract Background Sterile alpha motif (SAM domains are ~70 residues long and have been reported as common protein-protein interaction modules. This domain is found in a large number of proteins, including Polycomb group (PcG proteins and ETS family transcription factors. In this work, we report the cloning and functional characterization of a novel SAM domain-containing protein, which is predominantly expressed in retinal photoreceptors and the pineal gland and is designated mouse mr-s (major retinal SAM domain protein. Results mr-s is evolutionarily conserved from zebrafish through human, organisms through which the mechanism of photoreceptor development is also highly conserved. Phylogenetic analysis suggests that the SAM domain of mr-s is most closely related to a mouse polyhomeotic (ph ortholog, Mph1/Rae28, which is known as an epigenetic molecule involved in chromatin modifications. These findings provide the possibility that mr-s may play a critical role by regulating gene expression in photoreceptor development. mr-s is preferentially expressed in the photoreceptors at postnatal day 3–6 (P3-6, when photoreceptors undergo terminal differentiation, and in the adult pineal gland. Transcription of mr-s is directly regulated by the cone-rod homeodomain protein Crx. Immunoprecipitation assay showed that the mr-s protein self-associates mainly through the SAM domain-containing region as well as ph. The mr-s protein localizes mainly in the nucleus, when mr-s is overexpressed in HEK293T cells. Moreover, in the luciferase assays, we found that mr-s protein fused to GAL4 DNA-binding domain functions as a transcriptional repressor. We revealed that the repression activity of mr-s is not due to a homophilic interaction through its SAM domain but to the C-terminal region. Conclusion We identified a novel gene, mr-s, which is predominantly expressed in retinal photoreceptors and pineal gland. Based on its expression pattern and biochemical analysis

  20. 红蓝光联合阿达帕林凝胶治疗轻、中度痤疮的有效性和安全性分析%The Effectiveness and Safety Analysis of Treating Mild-to-moderate Acne by Red and Blue Light Combining Adapalene Gel

    Institute of Scientific and Technical Information of China (English)

    张蕊

    2015-01-01

    Objective:Analyze the effectiveness and safety of treating mild‐to‐moderate acne by red and blue light com‐bining Adapalene Gel .Methods:Select 210 patients with mild‐to‐moderate acne that has been hospitalized in our hospital and group them into three groups ,that is ,red and blue light group (70 cases) ,Adapalene Gel group (70 cases) and red and blue light combining Adapalene Gel group (70 cases) .Treat the red and blue light group with red and blue light exposure ,treat the Adapalene Gel group with external use of Adapalene Gel ,and treat the red and blue light combi‐ning Adapalene Gel group with red and blue light and external use of Adapalene .Compare the clinical effects of each group .Results:After treatment ,the skin lesion degree of red and blue light combining Adapalene Gel is evidently better than red and blue light group Adapalene Gel group and the difference has statistical significance (P<0 .05);the gener‐al effective rate of red and blue light combining Adapalene Gel is 94 .29% ,evidently higher than the red and blue light group and Adapalene Gel group ,and the difference has statistical significance (P< 0 .05) .Conclusion:The curative effect of treating mild‐to‐moderate acne by red and blue light combining Adapalene Gel is evidently better than red and blue light group and Adapalene Gel group ,and this kind of treatment is safe ,which is worthy of promoting on clinical treatment .%目的:分析红蓝光联合阿达帕林凝胶治疗轻、中度痤疮的有效性和安全性。方法:选取我院收治的210例轻、中度痤疮患者,将其随机分为三组,即红蓝光组(70例),阿达帕林凝胶组(70例),红蓝光联合阿达帕林凝胶组(70例)。红蓝光组给予红蓝光照射治疗,阿达帕林凝胶组给予外用的阿达帕林凝胶,红蓝光联合阿达帕林凝胶组给予红蓝光照射和外用的阿达帕林凝胶,比较各组临床疗效。结果:治疗后红蓝光联合阿达

  1. Canine retina has a primate fovea-like bouquet of cone photoreceptors which is affected by inherited macular degenerations.

    Directory of Open Access Journals (Sweden)

    William A Beltran

    Full Text Available Retinal areas of specialization confer vertebrates with the ability to scrutinize corresponding regions of their visual field with greater resolution. A highly specialized area found in haplorhine primates (including humans is the fovea centralis which is defined by a high density of cone photoreceptors connected individually to interneurons, and retinal ganglion cells (RGCs that are offset to form a pit lacking retinal capillaries and inner retinal neurons at its center. In dogs, a local increase in RGC density is found in a topographically comparable retinal area defined as the area centralis. While the canine retina is devoid of a foveal pit, no detailed examination of the photoreceptors within the area centralis has been reported. Using both in vivo and ex vivo imaging, we identified a retinal region with a primate fovea-like cone photoreceptor density but without the excavation of the inner retina. Similar anatomical structure observed in rare human subjects has been named fovea-plana. In addition, dogs with mutations in two different genes, that cause macular degeneration in humans, developed earliest disease at the newly-identified canine fovea-like area. Our results challenge the dogma that within the phylogenetic tree of mammals, haplorhine primates with a fovea are the sole lineage in which the retina has a central bouquet of cones. Furthermore, a predilection for naturally-occurring retinal degenerations to alter this cone-enriched area fills the void for a clinically-relevant animal model of human macular degenerations.

  2. Canine retina has a primate fovea-like bouquet of cone photoreceptors which is affected by inherited macular degenerations.

    Science.gov (United States)

    Beltran, William A; Cideciyan, Artur V; Guziewicz, Karina E; Iwabe, Simone; Swider, Malgorzata; Scott, Erin M; Savina, Svetlana V; Ruthel, Gordon; Stefano, Frank; Zhang, Lingli; Zorger, Richard; Sumaroka, Alexander; Jacobson, Samuel G; Aguirre, Gustavo D

    2014-01-01

    Retinal areas of specialization confer vertebrates with the ability to scrutinize corresponding regions of their visual field with greater resolution. A highly specialized area found in haplorhine primates (including humans) is the fovea centralis which is defined by a high density of cone photoreceptors connected individually to interneurons, and retinal ganglion cells (RGCs) that are offset to form a pit lacking retinal capillaries and inner retinal neurons at its center. In dogs, a local increase in RGC density is found in a topographically comparable retinal area defined as the area centralis. While the canine retina is devoid of a foveal pit, no detailed examination of the photoreceptors within the area centralis has been reported. Using both in vivo and ex vivo imaging, we identified a retinal region with a primate fovea-like cone photoreceptor density but without the excavation of the inner retina. Similar anatomical structure observed in rare human subjects has been named fovea-plana. In addition, dogs with mutations in two different genes, that cause macular degeneration in humans, developed earliest disease at the newly-identified canine fovea-like area. Our results challenge the dogma that within the phylogenetic tree of mammals, haplorhine primates with a fovea are the sole lineage in which the retina has a central bouquet of cones. Furthermore, a predilection for naturally-occurring retinal degenerations to alter this cone-enriched area fills the void for a clinically-relevant animal model of human macular degenerations.

  3. Canine Retina Has a Primate Fovea-Like Bouquet of Cone Photoreceptors Which Is Affected by Inherited Macular Degenerations

    OpenAIRE

    Beltran, William A.; Artur V Cideciyan; Karina E Guziewicz; Simone Iwabe; Malgorzata Swider; Scott, Erin M.; Savina, Svetlana V.; Gordon Ruthel; Frank Stefano; Lingli Zhang; Richard Zorger; Alexander Sumaroka; Samuel G Jacobson; Aguirre, Gustavo D.

    2014-01-01

    Retinal areas of specialization confer vertebrates with the ability to scrutinize corresponding regions of their visual field with greater resolution. A highly specialized area found in haplorhine primates (including humans) is the fovea centralis which is defined by a high density of cone photoreceptors connected individually to interneurons, and retinal ganglion cells (RGCs) that are offset to form a pit lacking retinal capillaries and inner retinal neurons at its center. In dogs, a local i...

  4. Observation of clinical efficacy of red blue light irradiation for 198 cases of acne vulgaris%红蓝光照射治疗198例痤疮的临床疗效观察

    Institute of Scientific and Technical Information of China (English)

    姬静静; 杨卫涌; 朱洁丽; 安永涛

    2015-01-01

    目的:观察红蓝光照射治疗痤疮的临床疗效.方法:将198例痤疮患者随机分为治疗组和对照组,对照组给予丹参酮胶囊口服,克林霉素磷酸酯凝胶外敷.治疗组除给予以上药物外,配合红蓝光交替照射面部痤疮部位.一个月后对两组患者疗效进行评价.结果:治疗组治愈率为45.9%,显效率为30.6%,对照组治愈率为31.0%,显效率为21.0%,X2=9.87,P<0.05,差异明显.结论:红蓝光交替照射治疗痤疮疗效显著,临床上可以推广使用.%Objective: To observe the clinical effect of red blue light irradiation in the treatment of acne.Methods: 198 cases of patients with acne were randomly divided into the treatment group and the control group, the control group was given oral Danshentong capsule, clindamycin phosphate gel for external application. In addition to the treatment group to give the above, with the red blue light irradiation of facial acne. After a month, the efficacy of the two groups of patients were evaluated.Results: the cure rate of the treatment group was 45.9%, the cure rate was 30.6%, the cure rate was 31% in the control group, 21% in the control group, X2 = 9.87, P < 0.05, the difference was obvious. Conclusion: red and blue light irradiation in the treatment of acne vulgaris is effective, can be used in clinic.

  5. 探讨茵陈五苓散联合蓝光治疗新生儿黄疸的临床效果%Efficacy of Yinchen Wuling San Combined Blue Light in Treatment of Neonatal Jaundice

    Institute of Scientific and Technical Information of China (English)

    许英

    2015-01-01

    ObjectiveTo explore the clinical curative effect yinchen wuling san and blue light in patients with neonatal jaundice.MethodsSixty patients with jaundice infants were randomly divided into research group and the control group,control group routine comprehensive treatment,and at the same time with phototherapy indications for blue light,the treatment group was based on the add yinchen wuling san. Results The team in serum total bilirubin level daily drop to 205 μmol/L used to time significantly shorter than the control group(P< 0.05),group total effective rate was better than control group(P< 0.05),the adverse reaction rate was smaler than in the control group(P< 0.05).Conclusion The combination of jaundice infants take wormwood chen wuling scattered blue light treatment effect is good,less adverse reactions.%目的:探究对新生儿黄疸患者采用茵陈五苓散联合蓝光进行治疗的临床疗效。方法60例黄疸新生儿随机均分为研究组和对照组。对照组常规综合治疗,同时以光疗指征给予蓝光照射;治疗组则在此基础上加服茵陈五苓散。结果研究组血清中总胆红素水平每日下降到205μmol/L所用去的时间比对照组短(P<0.05);研究组总有效率比对照组好(P<0.05);不良反应率比对照组小(P<0.05)。结论黄疸新生儿采取茵陈五苓散结合蓝光进行治疗效果好,不良反应少。

  6. Activation of autophagy in photoreceptor necroptosis after experimental retinal detachment

    Institute of Scientific and Technical Information of China (English)

    Kai; Dong; Zi-Cheng; Zhu; Feng-Hua; Wang; Gen-Jie; Ke; Zhang; Yu; Xun; Xu

    2014-01-01

    AIM:To investigate whether photoreceptor necroptosis induced by z-VAD-FMK(pan caspase inhibitor) was involved the activation of autophagy and whether Necrostatin-1, a specific necroptosis inhibitor, could inhibit this induction of autophagy after experimental retinal detachment.METHODS:Experimental retinal detachment models were created in Sprague-Dawley rats by subretinal injection of sodium hyaluronate and subretinal injections of z-VAD-FMK, vehicle or z-VAD-FMK plus Necrostatin-1.Three days after retinal detachment, morphologic changes were observed by transmission electron microscopy. In other animals, retinas were subjected to immunoprecipitation and Western Blotting, then probed with anti-RIP1, phosphoserine, LC-3II or caspase 8antibody.RESULTS:It was proved by immunoprecipitation and western blotting, that photoreceptor necroptosis was mediated by caspase-8 inhibition and receptor interacting protein kinase(RIP1) phosphorylation activation. Transmission electron microscope and western blotting results indicated that photoreceptornecroptosis was involved the LC-3II and autophagosomes induction. We also discovered Necrostatin-1 could inhibit RIP1 phosphorylation and LC-3II induction.CONCLUSION:These data firstly indicate photoreceptor necroptosis is associated with the activation of autophagy. Necrostatin-1 protects photoreceptors from necroptosis and autophagy by down-regulation of RIP1 phosphorylation and LC-3II.

  7. Waveguide Modes and Refractive Index in Photoreceptors of Invertebrates

    NARCIS (Netherlands)

    Stavenga, D.G.

    1975-01-01

    The refractive index of visual photoreceptors, if estimated by utilizing waveguide propagation, has to be corrected by a factor depending on the occurring mode. The correction factor is presented graphically for a number of relevant modes. Applied to the honeybee rhabdoms, it is shown that the

  8. Angular sensitivity of blowfly photoreceptors : broadening by artificial electrical coupling

    NARCIS (Netherlands)

    Smakman, J.G.J.; Stavenga, D.G.

    1987-01-01

    1. Electrical coupling between R1-6 photoreceptors was investigated by measuring angular sensitivities and quantum bumps. 2. Recordings were made from two extreme types of cells: Type a: cells with a diffraction-like angular sensitivity profile. Only large bumps could be obtained from these cells. T

  9. Diurnal Changes in Angular Sensitivity of Crab Photoreceptors

    NARCIS (Netherlands)

    Leggett, L.M.W.; Stavenga, D.G.

    1981-01-01

    The electrophysiological and anatomical consequences of diurnal changes in screening pigment position were investigated in the apposition eye of the portunid crab Scylla serrata. Intracellular recordings revealed that the acceptance angles of dark-adapted photoreceptors enlarged up to four-fold at n

  10. Three spectrally distinct photoreceptors in diurnal and nocturnal Australian ants.

    Science.gov (United States)

    Ogawa, Yuri; Falkowski, Marcin; Narendra, Ajay; Zeil, Jochen; Hemmi, Jan M

    2015-06-07

    Ants are thought to be special among Hymenopterans in having only dichromatic colour vision based on two spectrally distinct photoreceptors. Many ants are highly visual animals, however, and use vision extensively for navigation. We show here that two congeneric day- and night-active Australian ants have three spectrally distinct photoreceptor types, potentially supporting trichromatic colour vision. Electroretinogram recordings show the presence of three spectral sensitivities with peaks (λmax) at 370, 450 and 550 nm in the night-active Myrmecia vindex and peaks at 370, 470 and 510 nm in the day-active Myrmecia croslandi. Intracellular electrophysiology on individual photoreceptors confirmed that the night-active M. vindex has three spectral sensitivities with peaks (λmax) at 370, 430 and 550 nm. A large number of the intracellular recordings in the night-active M. vindex show unusually broad-band spectral sensitivities, suggesting that photoreceptors may be coupled. Spectral measurements at different temporal frequencies revealed that the ultraviolet receptors are comparatively slow. We discuss the adaptive significance and the probability of trichromacy in Myrmecia ants in the context of dim light vision and visual navigation. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  11. CNGA3 mutations in hereditary cone photoreceptor disorders

    NARCIS (Netherlands)

    Wissinger, B; Gamer, D; Jagle, H; Giorda, R; Marx, T; Mayer, S; Tippmann, S; Broghammer, M; Jurklies, B; Rosenberg, T; Jacobson, SG; Sener, EC; Tatlipinar, S; Hoyng, CB; Castellan, C; Bitoun, P; Andreasson, S; Rudolph, G; Kellner, U; Lorenz, B; Wolff, G; Verellen-Dumoulin, C; Schwartz, M; Cremers, FPM; Apfelstedt-ylla, E; Zrenner, E; Salati, R; Sharpe, LT; Kohl, S

    2001-01-01

    We recently showed that mutations in the CNGA3 gene encoding the alpha -subunit of the cone photoreceptor cGMP-gated channel cause autosomal recessive complete achromatopsia linked to chromosome 2q11. We now report the results of a first comprehensive screening for CNGA3 mutations in a cohort of 258

  12. Diurnal Changes in Angular Sensitivity of Crab Photoreceptors

    NARCIS (Netherlands)

    Leggett, L.M.W.; Stavenga, D.G.

    1981-01-01

    The electrophysiological and anatomical consequences of diurnal changes in screening pigment position were investigated in the apposition eye of the portunid crab Scylla serrata. Intracellular recordings revealed that the acceptance angles of dark-adapted photoreceptors enlarged up to four-fold at

  13. CNGA3 mutations in hereditary cone photoreceptor disorders

    NARCIS (Netherlands)

    Wissinger, B; Gamer, D; Jagle, H; Giorda, R; Marx, T; Mayer, S; Tippmann, S; Broghammer, M; Jurklies, B; Rosenberg, T; Jacobson, SG; Sener, EC; Tatlipinar, S; Hoyng, CB; Castellan, C; Bitoun, P; Andreasson, S; Rudolph, G; Kellner, U; Lorenz, B; Wolff, G; Verellen-Dumoulin, C; Schwartz, M; Cremers, FPM; Apfelstedt-ylla, E; Zrenner, E; Salati, R; Sharpe, LT; Kohl, S

    2001-01-01

    We recently showed that mutations in the CNGA3 gene encoding the alpha -subunit of the cone photoreceptor cGMP-gated channel cause autosomal recessive complete achromatopsia linked to chromosome 2q11. We now report the results of a first comprehensive screening for CNGA3 mutations in a cohort of 258

  14. Protein and signaling networks in vertebrate photoreceptor cells

    Directory of Open Access Journals (Sweden)

    Karl-Wilhelm eKoch

    2015-11-01

    Full Text Available Vertebrate photoreceptor cells are exquisite light detectors operating under very dim and bright illumination. The photoexcitation and adaptation machinery in photoreceptor cells consists of protein complexes that can form highly ordered supramolecular structures and control the homeostasis and mutual dependence of the secondary messengers cGMP and Ca2+. The visual pigment in rod photoreceptors, the G protein-coupled receptor rhodopsin is organized in tracks of dimers thereby providing a signaling platform for the dynamic scaffolding of the G protein transducin. Illuminated rhodopsin is turned off by phosphorylation catalyzed by rhodopsin kinase GRK1 under control of Ca2+-recoverin. The GRK1 protein complex partly assembles in lipid raft structures, where shutting off rhodopsin seems to be more effective. Re-synthesis of cGMP is another crucial step in the recovery of the photoresponse after illumination. It is catalyzed by membrane bound sensory guanylate cyclases and is regulated by specific neuronal Ca2+-sensor proteins called GCAPs. At least one guanylate cyclase (ROS-GC1 was shown to be part of a multiprotein complex having strong interactions with the cytoskeleton and being controlled in a multimodal Ca2+-dependent fashion. The final target of the cGMP signaling cascade is a cyclic nucleotide-gated channel that is a hetero-oligomeric protein located in the plasma membrane and interacting with accessory proteins in highly organized microdomains. We summarize results and interpretations of findings related to the inhomogeneous organization of signaling units in photoreceptor outer segments.

  15. GBF1, a transcription factor of blue light signaling in Arabidopsis, is degraded in the dark by a proteasome-mediated pathway independent of COP1 and SPA1.

    Science.gov (United States)

    Mallappa, Chandrashekara; Singh, Aparna; Ram, Hathi; Chattopadhyay, Sudip

    2008-12-19

    Arabidopsis GBF1/ZBF2 is a bZIP transcription factor that plays dual but opposite regulatory roles in cryptochrome-mediated blue light signaling. Here, we show the genetic and molecular interrelation of GBF1 with two well characterized negative regulators of light signaling, COP1 and SPA1, in photomorphogenic growth and light-regulated gene expression. Our results further reveal that GBF1 protein is less abundant in the dark-grown seedlings and is degraded by a proteasome-mediated pathway independent of COP1 and SPA1. Furthermore, COP1 physically interacts with GBF1 and is required for the optimum accumulation of GBF1 protein in light-grown seedlings. Taken together, this study provides a mechanistic view of concerted function of three important regulators in Arabidopsis seedling development.

  16. A New Distyrylarylene Derivative Used as Blue Light Emitter in Organic Electroluminescent Device%一种新型联苯乙烯衍生物--蓝色有机电致发光材料

    Institute of Scientific and Technical Information of China (English)

    郑新友; 朱文清; 吴有智; 张步新; 蒋雪茵; 张志林; 许少鸿

    2002-01-01

    A new blue electroluminescent material, distyrylarylene(DSA) derivative, 4,4'-bis[2,2-(1-naphthyl,phenyl)vinyl]-l,l'-biphenyl(NPVBi) is designed and synthesized. The DSA derivative shows better thermal stability because of its high glass transition temperature. A blue organic light emitting diode(OLED) with the structure ITO/TPD/NPVBi/Alq/LiF/A1 is studied. The electroluminescent(EL) spectrum of the OLED exhibits that light emission originates from NPVBi with a peak at 460 nm, its Commission Internationale de l' Eclairage(CIE) color coordinates are x = 0.16, y = 0.15, and showing independence of CIE color coordinates on current density. The new DSA derivative is expectable as a new candidate for blue light emitter in OLEDs.

  17. Evaluation of the temperature-dependent internal quantum efficiency and the light-extraction efficiency in a GaN-based blue light-emitting diode by using a rate equation model

    Science.gov (United States)

    Choi, Young-Hwan; Ryu, Guen-Hwan; Ryu, Han-Youl

    2016-10-01

    The internal quantum efficiency (IQE) and the light extraction efficiency (LEE) of a GaN-based blue light-emitting diode (LED) are evaluated separately in the temperature range between 20 to 80 °C. The theoretical IQE model based on the carrier rate equation of semiconductors is applied to determine the IQE and the LEE separately from a measured external quantum efficiency (EQE) versus current relation for the LED sample. While the peak EQE of the measured sample decreases by 3.2 % as the temperature increases from 20 to 80 °C, it is found that the peak IQE decreases by 4.5 % and the LEE increases by 1.5 %.

  18. The opportunistic human pathogen Acinetobacter baumannii senses and responds to light.

    Science.gov (United States)

    Mussi, María A; Gaddy, Jennifer A; Cabruja, Matías; Arivett, Brock A; Viale, Alejandro M; Rasia, Rodolfo; Actis, Luis A

    2010-12-01

    Light is a ubiquitous environmental signal that many organisms sense and respond to by modulating their physiological responses accordingly. While this is an expected response among phototrophic microorganisms, the ability of chemotrophic prokaryotes to sense and react to light has become a puzzling and novel issue in bacterial physiology, particularly among bacterial pathogens. In this work, we show that the opportunistic pathogen Acinetobacter baumannii senses and responds to blue light. Motility and formation of biofilms and pellicles were observed only when bacterial cells were incubated in darkness. In contrast, the killing of Candida albicans filaments was enhanced when they were cocultured with bacteria under light. These bacterial responses depend on the expression of the A. baumannii ATCC 17978 A1S_2225 gene, which codes for an 18.6-kDa protein that contains an N-terminal blue-light-sensing-using flavin (BLUF) domain and lacks a detectable output domain(s). Spectral analyses of the purified recombinant protein showed its ability to sense light by a red shift upon illumination. Therefore, the A1S_2225 gene, which is present in several members of the Acinetobacter genus, was named blue-light-sensing A (blsA). Interestingly, temperature plays a role in the ability of A. baumannii to sense and respond to light via the BlsA photoreceptor protein.

  19. Transient photoreceptor deconstruction by CNTF enhances rAAV-mediated cone functional rescue in late stage CNGB3-achromatopsia.

    Science.gov (United States)

    Komáromy, András M; Rowlan, Jessica S; Corr, Amanda T Parton; Reinstein, Shelby L; Boye, Sanford L; Cooper, Ann E; Gonzalez, Amaliris; Levy, Britt; Wen, Rong; Hauswirth, William W; Beltran, William A; Aguirre, Gustavo D

    2013-06-01

    Achromatopsia is a genetic disorder of cones, and one of the most common forms is a channelopathy caused by mutations in the β-subunit, CNGB3, of the cone cyclic nucleotide-gated (CNG) channel. Recombinant adeno-associated virus of serotype 5 (rAAV5)-mediated gene transfer of human CNGB3 cDNA to mutant dog cones results in functional and structural rescue in dogs 1 year. We now test a new therapeutic concept by combining gene therapy with the administration of ciliary neurotrophic factor (CNTF). Intravitreal CNTF causes transient dedifferentiation of photoreceptors, a process called deconstruction, whereby visual cells become immature with short outer segments, and decreased retinal function and gene expression that subsequently return to normal. Cone function was successfully rescued in all mutant dogs treated between 14 and 42 months of age with this strategy. CNTF-mediated deconstruction and regeneration of the photoreceptor outer segments prepares the mutant cones optimally for gene augmentation therapy.

  20. Retinal Thickening and Photoreceptor Loss in HIV Eyes without Retinitis.

    Directory of Open Access Journals (Sweden)

    Cheryl A Arcinue

    Full Text Available To determine the presence of structural changes in HIV retinae (i.e., photoreceptor density and retinal thickness in the macula compared with age-matched HIV-negative controls.Cohort of patients with known HIV under CART (combination Antiretroviral Therapy treatment were examined with a flood-illuminated retinal AO camera to assess the cone photoreceptor mosaic and spectral-domain optical coherence tomography (SD-OCT to assess retinal layers and retinal thickness.Twenty-four eyes of 12 patients (n = 6 HIV-positive and 6 HIV-negative were imaged with the adaptive optics camera. In each of the regions of interest studied (nasal, temporal, superior, inferior, the HIV group had significantly less mean cone photoreceptor density compared with age-matched controls (difference range, 4,308-6,872 cones/mm2. A different subset of forty eyes of 20 patients (n = 10 HIV-positive and 10 HIV-negative was included in the retinal thickness measurements and retinal layer segmentation with the SD-OCT. We observed significant thickening in HIV positive eyes in the total retinal thickness at the foveal center, and in each of the three horizontal B-scans (through the macular center, superior, and inferior to the fovea. We also noted that the inner retina (combined thickness from ILM through RNFL to GCL layer was also significantly thickened in all the different locations scanned compared with HIV-negative controls.Our present study shows that the cone photoreceptor density is significantly reduced in HIV retinae compared with age-matched controls. HIV retinae also have increased macular retinal thickness that may be caused by inner retinal edema secondary to retinovascular disease in HIV. The interaction of photoreceptors with the aging RPE, as well as possible low-grade ocular inflammation causing diffuse inner retinal edema, may be the key to the progressive vision changes in HIV-positive patients without overt retinitis.

  1. A hybrid photoreceptor expressing both rod and cone genes in a mouse model of enhanced S-cone syndrome.

    Directory of Open Access Journals (Sweden)

    Joseph C Corbo

    2005-08-01

    Full Text Available Rod and cone photoreceptors subserve vision under dim and bright light conditions, respectively. The differences in their function are thought to stem from their different gene expression patterns, morphologies, and synaptic connectivities. In this study, we have examined the photoreceptor cells of the retinal degeneration 7(rd7 mutant mouse, a model for the human enhanced S-cone syndrome (ESCS. This mutant carries a spontaneous deletion in the mouse ortholog of NR2E3, an orphan nuclear receptor transcription factor mutated in ESCS. Employing microarray and in situ hybridization analysis we have found that the rd7 retina contains a modestly increased number of S-opsin-expressing cells that ultrastructurally appear to be normal cones. Strikingly, the majority of the photoreceptors in the rd7 retina represent a morphologically hybrid cell type that expresses both rod- and cone-specific genes. In addition, in situ hybridization screening of genes shown to be up-regulated in the rd7 mutant retina by microarray identified ten new cone-specific or cone-enriched genes with a wide range of biochemical functions, including two genes specifically involved in glucose/glycogen metabolism. We suggest that the abnormal electroretinograms, slow retinal degeneration, and retinal dysmorphology seen in humans with ESCS may, in part, be attributable to the aberrant function of a hybrid photoreceptor cell type similar to that identified in this study. The functional diversity of the novel cone-specific genes identified here indicates molecular differences between rods and cones extending far beyond those previously discovered.

  2. Multipotent stem cells isolated from the adult mouse retina are capable of producing functional photoreceptor cells.

    Science.gov (United States)

    Li, Tianqing; Lewallen, Michelle; Chen, Shuyi; Yu, Wei; Zhang, Nian; Xie, Ting

    2013-06-01

    Various stem cell types have been tested for their potential application in treating photoreceptor degenerative diseases, such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Only embryonic stem cells (ESCs) have so far been shown to generate functional photoreceptor cells restoring light response of photoreceptor-deficient mice, but there is still some concern of tumor formation. In this study, we have successfully cultured Nestin(+)Sox2(+)Pax6(+) multipotent retinal stem cells (RSCs) from the adult mouse retina, which are capable of producing functional photoreceptor cells that restore the light response of photoreceptor-deficient rd1 mutant mice following transplantation. After they have been expanded for over 35 passages in the presence of FGF and EGF, the cultured RSCs still maintain stable proliferation and differentiation potential. Under proper differentiation conditions, they can differentiate into all the major retinal cell types found in the adult retina. More importantly, they can efficiently differentiate into photoreceptor cells under optimized differentiation conditions. Following transplantation into the subretinal space of slowly degenerating rd7 mutant eyes, RSC-derived photoreceptor cells integrate into the retina, morphologically resembling endogenous photoreceptors and forming synapases with resident retinal neurons. When transplanted into eyes of photoreceptor-deficient rd1 mutant mice, a RP model, RSC-derived photoreceptors can partially restore light response, indicating that those RSC-derived photoreceptors are functional. Finally, there is no evidence for tumor formation in the photoreceptor-transplanted eyes. Therefore, this study has demonstrated that RSCs isolated from the adult retina have the potential of producing functional photoreceptor cells that can potentially restore lost vision caused by loss of photoreceptor cells in RP and AMD.

  3. Mutant carbonic anhydrase 4 impairs pH regulation and causes retinal photoreceptor degeneration.

    Science.gov (United States)

    Yang, Zhenglin; Alvarez, Bernardo V; Chakarova, Christina; Jiang, Li; Karan, Goutam; Frederick, Jeanne M; Zhao, Yu; Sauvé, Yves; Li, Xi; Zrenner, Eberhart; Wissinger, Bernd; Hollander, Anneke I Den; Katz, Bradley; Baehr, Wolfgang; Cremers, Frans P; Casey, Joseph R; Bhattacharya, Shomi S; Zhang, Kang

    2005-01-15

    Retina and retinal pigment epithelium (RPE) belong to the metabolically most active tissues in the human body. Efficient removal of acid load from retina and RPE is a critical function mediated by the choriocapillaris. However, the mechanism by which pH homeostasis is maintained is largely unknown. Here, we show that a functional complex of carbonic anhydrase 4 (CA4) and Na+/bicarbonate co-transporter 1 (NBC1) is specifically expressed in the choriocapillaris and that missense mutations in CA4 linked to autosomal dominant rod-cone dystrophy disrupt NBC1-mediated HCO3- transport. Our results identify a novel pathogenic pathway in which a defect in a functional complex involved in maintaining pH balances, but not expressed in retina or RPE, leads to photoreceptor degeneration. The importance of a functional CA4 for survival of photoreceptors implies that CA inhibitors, which are widely used as medications, particularly in the treatment of glaucoma, may have long-term adverse effects on vision.

  4. A role for the extracellular domain of Crumbs in morphogenesis of Drosophila photoreceptor cells.

    Science.gov (United States)

    Richard, Mélisande; Muschalik, Nadine; Grawe, Ferdi; Ozüyaman, Susann; Knust, Elisabeth

    2009-12-01

    Morphogenesis of Drosophila photoreceptor cells includes the subdivision of the apical membrane into the photosensitive rhabdomere and the associated stalk membrane, as well as a considerable elongation of the cell. Drosophila Crumbs (Crb), an evolutionarily conserved transmembrane protein, organizes an apical protein scaffold, which is required for elongation of the photoreceptor cell and extension of the stalk membrane. To further elucidate the role played by different Crb domains during eye morphogenesis, we performed a structure-function analysis in the eye. The analysis showed that the three variants tested, namely full-length Crb, the membrane-bound intracellular domain and the extracellular domain were able to rescue the elongation defects of crb mutant rhabdomeres. However, only full-length Crb and the membrane-bound intracellular domain could partially restore the length of the stalk membrane, while the extracellular domain failed to do so. This failure was associated with the inability of the extracellular domain to recruit beta(Heavy)-spectrin to the stalk membrane. These results highlight the functional importance of the extracellular domain of Crb in the Drosophila eye. They are in line with previous observations, which showed that mutations in the extracellular domain of human CRB1 are associated with retinitis pigmentosa 12 and Leber congenital amaurosis, two severe forms of retinal dystrophy.

  5. Crumbs limits oxidase-dependent signaling to maintain epithelial integrity and prevent photoreceptor cell death.

    Science.gov (United States)

    Chartier, François J-M; Hardy, Émilie J-L; Laprise, Patrick

    2012-09-17

    Drosophila melanogaster Crumbs (Crb) and its mammalian orthologues (CRB1-3) share evolutionarily conserved but poorly defined roles in regulating epithelial polarity and, in photoreceptor cells, morphogenesis and stability. Elucidating the molecular mechanisms of Crb function is vital, as mutations in the human CRB1 gene cause retinal dystrophies. Here, we report that Crb restricts Rac1-NADPH oxidase-dependent superoxide production in epithelia and photoreceptor cells. Reduction of superoxide levels rescued epithelial defects in crb mutant embryos, demonstrating that limitation of superoxide production is a crucial function of Crb and that NADPH oxidase and superoxide contribute to the molecular network regulating epithelial tissue organization. We further show that reduction of Rac1 or NADPH oxidase activity or quenching of reactive oxygen species prevented degeneration of Crb-deficient retinas. Thus, Crb fulfills a protective role during light exposure by limiting oxidative damage resulting from Rac1-NADPH oxidase complex activity. Collectively, our results elucidate an important mechanism by which Crb functions in epithelial organization and the prevention of retinal degeneration.

  6. Targeted RP9 ablation and mutagenesis in mouse photoreceptor cells by CRISPR-Cas9

    Science.gov (United States)

    Lv, Ji-Neng; Zhou, Gao-Hui; Chen, Xuejiao; Chen, Hui; Wu, Kun-Chao; Xiang, Lue; Lei, Xin-Lan; Zhang, Xiao; Wu, Rong-Han; Jin, Zi-Bing

    2017-01-01

    Precursor messenger RNA (Pre-mRNA) splicing is an essential biological process in eukaryotic cells. Genetic mutations in many spliceosome genes confer human eye diseases. Mutations in the pre-mRNA splicing factor, RP9 (also known as PAP1), predispose autosomal dominant retinitis pigmentosa (adRP) with an early onset and severe vision loss. However, underlying molecular mechanisms of the RP9 mutation causing photoreceptor degeneration remains fully unknown. Here, we utilize the CRISPR/Cas9 system to generate both the Rp9 gene knockout (KO) and point mutation knock in (KI) (Rp9, c.A386T, P.H129L) which is analogous to the reported one in the retinitis pigmentosa patients (RP9, c.A410T, P.H137L) in 661 W retinal photoreceptor cells in vitro. We found that proliferation and migration were significantly decreased in the mutated cells. Gene expression profiling by RNA-Seq demonstrated that RP associated genes, Fscn2 and Bbs2, were down-regulated in the mutated cells. Furthermore, pre-mRNA splicing of the Fscn2 gene was markedly affected. Our findings reveal a functional relationship between the ubiquitously expressing RP9 and the disease-specific gene, thereafter provide a new insight of disease mechanism in RP9-related retinitis pigmentosa. PMID:28216641

  7. The Retinal Pigment Epithelium: a Convenient Source of New Photoreceptor cells?

    Directory of Open Access Journals (Sweden)

    Shu-Zhen Wang

    2014-01-01

    Full Text Available Recent success in restoring visual function through photoreceptor replacement in mouse models of photoreceptor degeneration intensifies the need to generate or regenerate photoreceptor cells for the ultimate goal of using cell replacement therapy for blindness caused by photoreceptor degeneration. Current research on deriving new photoreceptors for replacement, as regenerative medicine in general, focuses on the use of embryonic stem cells and induced pluripotent stem (iPS cells to generate transplantable cells. Nonetheless, naturally occurring regeneration, such as wound healing, involves awakening cells at or near a wound site to produce new cells needed to heal the wound. Here we discuss the possibility of tweaking an ocular tissue, the retinal pigment epithelium (RPE, to produce photoreceptor cells in situ in the eye. Unlike the neural retina, the RPE in adult mammals maintains cell proliferation capability. Furthermore, progeny cells from RPE proliferation may differentiate into cells other than RPE. The combination of proliferation and plasticity opens a question of whether they could be channeled by a regulatory gene with pro-photoreceptor activity towards photoreceptor production. Studies using embryonic chick and transgenic mouse showed that indeed photoreceptor-like cells were produced in culture and in vivo in the eye using genedirected reprogramming of RPE cells, supporting the feasibility of using the RPE as a convenient source of new photoreceptor cells for in situ retinal repair without involving cell transplantation.

  8. Control of a four-color sensing photoreceptor by a two-color sensing photoreceptor reveals complex light regulation in cyanobacteria

    OpenAIRE

    Bussell, Adam N.; Kehoe, David M.

    2013-01-01

    Photoreceptors are biologically important for sensing changes in the color and intensity of ambient light and, for photosynthetic organisms, processing this light information to optimize food production through photosynthesis. Cyanobacteria are an evolutionarily and ecologically important prokaryotic group of oxygenic photosynthesizers that contain cyanobacteriochrome (CBCR) photoreceptors, whose family members sense nearly the entire visible spectrum of light colors. Some cyanobacteria conta...

  9. Multipotent stem cells isolated from the adult mouse retina are capable of producing functional photoreceptor cells

    Institute of Scientific and Technical Information of China (English)

    Tianqing Li; Michelle Lewallen; Shuyi Chen; Wei Yu; Nian Zhang; Ting Xie

    2013-01-01

    Various stem cell types have been tested for their potential application in treating photoreceptor degenerative diseases,such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD).Only embryonic stem cells (ESCs) have so far been shown to generate functional photoreceptor cells restoring light response of photoreceptordeficient mice,but there is still some concern of tumor formation.In this study,we have successfully cultured Nestin+Sox2+Pax6+ multipotent retinal stem cells (RSCs) from the adult mouse retina,which are capable of producing functional photoreceptor cells that restore the light response of photoreceptor-deficient rd1 mutant mice following transplantation.After they have been expanded for over 35 passages in the presence of FGF and EGF,the cultured RSCs still maintain stable proliferation and differentiation potential.Under proper differentiation conditions,they can differentiate into all the major retinal cell types found in the adult retina.More importantly,they can efficiently differentiate into photoreceptor cells under optimized differentiation conditions.Following transplantation into the subretinal space of slowly degenerating rd7 mutant eyes,RSC-derived photoreceptor cells integrate into the retina,morphologically resembling endogenous photoreceptors and forming synapases with resident retinal neurons.When transplanted into eyes of photoreceptor-deficient rd1 mutant mice,a RP model,RSC-derived photoreceptors can partially restore light response,indicating that those RSC-derived photoreceptors are functional.Finally,there is no evidence for tumor formation in the photoreceptor-transplanted eyes.Therefore,this study has demonstrated that RSCs isolated from the adult retina have the potential of producing functional photoreceptor cells that can potentially restore lost vision caused by loss of photoreceptor cells in RP and AMD.

  10. Deafferented Adult Rod Bipolar Cells Create New Synapses with Photoreceptors to Restore Vision.

    Science.gov (United States)

    Beier, Corinne; Hovhannisyan, Anahit; Weiser, Sydney; Kung, Jennifer; Lee, Seungjun; Lee, Dae Yeong; Huie, Philip; Dalal, Roopa; Palanker, Daniel; Sher, Alexander

    2017-04-26

    Upon degeneration of photoreceptors in the adult retina, interneurons, including bipolar cells, exhibit a plastic response leading to their aberrant rewiring. Photoreceptor reintroduction has been suggested as a potential approach to sight restoration, but the ability of deafferented bipolar cells to establish functional synapses with photoreceptors is poorly understood. Here we use photocoagulation to selectively destroy photoreceptors in adult rabbits while preserving the inner retina. We find that rods and cones shift into the ablation zone over several weeks, reducing the blind spot at scotopic and photopic luminances. During recovery, rod and cone bipolar cells exhibit markedly different responses to deafferentation. Rod bipolar cells extend their dendrites to form new synapses with healthy photoreceptors outside the lesion, thereby restoring visual function in the deafferented retina. Secretagogin-positive cone bipolar cells did not exhibit such obvious dendritic restructuring. These findings are encouraging to the idea of photoreceptor reintroduction for vision restoration in patients blinded by retinal degeneration. At the same time, they draw attention to the postsynaptic side of photoreceptor reintroduction; various bipolar cell types, representing different visual pathways, vary in their response to the photoreceptor loss and in their consequent dendritic restructuring.SIGNIFICANCE STATEMENT Loss of photoreceptors during retinal degeneration results in permanent visual impairment. Strategies for vision restoration based on the reintroduction of photoreceptors inherently rely on the ability of the remaining retinal neurons to correctly synapse with new photoreceptors. We show that deafferented bipolar cells in the adult mammalian retina can reconnect to rods and cones and restore retinal sensitivity at scotopic and photopic luminances. Rod bipolar cells extend their dendrites to form new synapses with healthy rod photoreceptors. These findings support the

  11. Extracellular electrical activity from the photoreceptors of midge

    Indian Academy of Sciences (India)

    A A Babrekar; G R Kulkarni; B B Nath; P B Vidyasagar

    2004-09-01

    The ontogeny of photosensitivity has been studied in a holometabolous insect, the midge Chironomus ramosus. The life cycle of midges shifts from an aquatic environment to a non-aquatic environment. Extracellular electrical activity of photoreceptor organs was recorded at larval and adult stages. We found an increase in photosensitivity as the larva metamorphosed to the adult stage. This is the first report of changes in photosensitivity during the development of any insect described in an ecological context.

  12. Adaptive potentiation in rod photoreceptors after light exposure.

    Science.gov (United States)

    McKeown, Alex S; Kraft, Timothy W

    2014-06-01

    Photoreceptors adapt to changes in illumination by altering transduction kinetics and sensitivity, thereby extending their working range. We describe a previously unknown form of rod photoreceptor adaptation in wild-type (WT) mice that manifests as a potentiation of the light response after periods of conditioning light exposure. We characterize the stimulus conditions that evoke this graded hypersensitivity and examine the molecular mechanisms of adaptation underlying the phenomenon. After exposure to periods of saturating illumination, rods show a 10-35% increase in circulating dark current, an adaptive potentiation (AP) to light exposure. This potentiation grows as exposure to light is extended up to 3 min and decreases with longer exposures. Cells return to their initial dark-adapted sensitivity with a time constant of recovery of ∼7 s. Halving the extracellular Mg concentration prolongs the adaptation, increasing the time constant of recovery to 13.3 s, but does not affect the magnitude of potentiation. In rods lacking guanylate cyclase activating proteins 1 and 2 (GCAP(-/-)), AP is more than doubled compared with WT rods, and halving the extracellular Mg concentration does not affect the recovery time constant. Rods from a mouse expressing cyclic nucleotide-gated channels incapable of binding calmodulin also showed a marked increase in the amplitude of AP. Application of an insulin-like growth factor-1 receptor (IGF-1R) kinase inhibitor (Tyrphostin AG1024) blocked AP, whereas application of an insulin receptor kinase inhibitor (HNMPA(AM)3) failed to do so. A broad-acting tyrosine phosphatase inhibitor (orthovanadate) also blocked AP. Our findings identify a unique form of adaptation in photoreceptors, so that they show transient hypersensitivity to light, and are consistent with a model in which light history, acting via the IGF-1R, can increase the sensitivity of rod photoreceptors, whereas the photocurrent overshoot is regulated by Ca-calmodulin and Ca(2

  13. Photoreceptor structure and function in patients with congenital achromatopsia.

    Science.gov (United States)

    Genead, Mohamed A; Fishman, Gerald A; Rha, Jungtae; Dubis, Adam M; Bonci, Daniela Maria O; Dubra, Alfredo; Stone, Edwin M; Neitz, Maureen; Carroll, Joseph

    2011-09-21

    To assess photoreceptor structure and function in patients with congenital achromatopsia. Twelve patients were enrolled. All patients underwent a complete ocular examination, spectral-domain optical coherence tomography (SD-OCT), full-field electroretinographic (ERG), and color vision testing. Macular microperimetry (MP; in four patients) and adaptive optics (AO) imaging (in nine patients) were also performed. Blood was drawn for screening of disease-causing genetic mutations. Mean (± SD) age was 30.8 (± 16.6) years. Mean best-corrected visual acuity was 0.85 (± 0.14) logarithm of the minimal angle of resolution (logMAR) units. Seven patients (58.3%) showed either an absent foveal reflex or nonspecific retinal pigment epithelium mottling to mild hypopigmentary changes on fundus examination. Two patients showed an atrophic-appearing macular lesion. On anomaloscopy, only 5 patients matched over the entire range from 0 to 73. SD-OCT examination showed a disruption or loss of the macular inner/outer segments (IS/OS) junction of the photoreceptors in 10 patients (83.3%). Seven of these patients showed an optically empty space at the level of the photoreceptors in the fovea. AO images of the photoreceptor mosaic were highly variable but significantly disrupted from normal. On ERG testing, 10 patients (83.3%) showed evidence of residual cone responses to a single-flash stimulus response. The macular MP testing showed that the overall mean retinal sensitivity was significantly lower than normal (12.0 vs. 16.9 dB, P achromatopsia should be useful in guiding selection of patients for future therapeutic trials as well as monitoring therapeutic response in these trials.

  14. Integrity of the cone photoreceptor mosaic in oligocone trichromacy

    DEFF Research Database (Denmark)

    Michaelides, Michel; Rha, Jungtae; Dees, Elise W;

    2011-01-01

    Oligocone trichromacy (OT) is an unusual cone dysfunction syndrome characterized by reduced visual acuity, mild photophobia, reduced amplitude of the cone electroretinogram with normal rod responses, normal fundus appearance, and normal or near-normal color vision. It has been proposed that these...... that these patients have a reduced number of normal functioning cones (oligocone). This paper has sought to evaluate the integrity of the cone photoreceptor mosaic in four patients previously described as having OT....

  15. Mitochondria Maintain Distinct Ca(2+) Pools in Cone Photoreceptors.

    Science.gov (United States)

    Giarmarco, Michelle M; Cleghorn, Whitney M; Sloat, Stephanie R; Hurley, James B; Brockerhoff, Susan E

    2017-02-22

    Ca(2+) ions have distinct roles in the outer segment, cell body, and synaptic terminal of photoreceptors. We tested the hypothesis that distinct Ca(2+) domains are maintained by Ca(2+) uptake into mitochondria. Serial block face scanning electron microscopy of zebrafish cones revealed that nearly 100 mitochondria cluster at the apical side of the inner segment, directly below the outer segment. The endoplasmic reticulum surrounds the basal and lateral surfaces of this cluster, but does not reach the apical surface or penetrate into the cluster. Using genetically encoded Ca(2+) sensors, we found that mitochondria take up Ca(2+) when it accumulates either in the cone cell body or outer segment. Blocking mitochondrial Ca(2+) uniporter activity compromises the ability of mitochondria to maintain distinct Ca(2+) domains. Together, our findings indicate that mitochondria can modulate subcellular functional specialization in photoreceptors.SIGNIFICANCE STATEMENT Ca(2+) homeostasis is essential for the survival and function of retinal photoreceptors. Separate pools of Ca(2+) regulate phototransduction in the outer segment, metabolism in the cell body, and neurotransmitter release at the synaptic terminal. We investigated the role of mitochondria in compartmentalization of Ca(2+) We found that mitochondria form a dense cluster that acts as a diffusion barrier between the outer segment and cell body. The cluster is surprisingly only partially surrounded by the endoplasmic reticulum, a key mediator of mitochondrial Ca(2+) uptake. Blocking the uptake of Ca(2+) by mitochondria causes redistribution of Ca(2+) throughout the cell. Our results show that mitochondrial Ca(2+) uptake in photoreceptors is complex and plays an essential role in normal function. Copyright © 2017 the authors 0270-6474/17/372061-12$15.00/0.

  16. Calcium channel-dependent molecular maturation of photoreceptor synapses.

    Directory of Open Access Journals (Sweden)

    Nawal Zabouri

    Full Text Available Several studies have shown the importance of calcium channels in the development and/or maturation of synapses. The Ca(V1.4(α(1F knockout mouse is a unique model to study the role of calcium channels in photoreceptor synapse formation. It features abnormal ribbon synapses and aberrant cone morphology. We investigated the expression and targeting of several key elements of ribbon synapses and analyzed the cone morphology in the Ca(V1.4(α(1F knockout retina. Our data demonstrate that most abnormalities occur after eye opening. Indeed, scaffolding proteins such as Bassoon and RIM2 are properly targeted at first, but their expression and localization are not maintained in adulthood. This indicates that either calcium or the Ca(V1.4 channel, or both are necessary for the maintenance of their normal expression and distribution in photoreceptors. Other proteins, such as Veli3 and PSD-95, also display abnormal expression in rods prior to eye opening. Conversely, vesicle related proteins appear normal. Our data demonstrate that the Ca(V1.4 channel is important for maintaining scaffolding proteins in the ribbon synapse but less vital for proteins related to vesicular release. This study also confirms that in adult retinae, cones show developmental features such as sprouting and synaptogenesis. Overall we present evidence that in the absence of the Ca(V1.4 channel, photoreceptor synapses remain immature and are unable to stabilize.

  17. NRL-Regulated Transcriptome Dynamics of Developing Rod Photoreceptors.

    Science.gov (United States)

    Kim, Jung-Woong; Yang, Hyun-Jin; Brooks, Matthew John; Zelinger, Lina; Karakülah, Gökhan; Gotoh, Norimoto; Boleda, Alexis; Gieser, Linn; Giuste, Felipe; Whitaker, Dustin Thad; Walton, Ashley; Villasmil, Rafael; Barb, Jennifer Joanna; Munson, Peter Jonathan; Kaya, Koray Dogan; Chaitankar, Vijender; Cogliati, Tiziana; Swaroop, Anand

    2016-11-22

    Gene regulatory networks (GRNs) guiding differentiation of cell types and cell assemblies in the nervous system are poorly understood because of inherent complexities and interdependence of signaling pathways. Here, we report transcriptome dynamics of differentiating rod photoreceptors in the mammalian retina. Given that the transcription factor NRL determines rod cell fate, we performed expression profiling of developing NRL-positive (rods) and NRL-negative (S-cone-like) mouse photoreceptors. We identified a large-scale, sharp transition in the transcriptome landscape between postnatal days 6 and 10 concordant with rod morphogenesis. Rod-specific temporal DNA methylation corroborated gene expression patterns. De novo assembly and alternative splicing analyses revealed previously unannotated rod-enriched transcripts and the role of NRL in transcript maturation. Furthermore, we defined the relationship of NRL with other transcriptional regulators and downstream cognate effectors. Our studies provide the framework for comprehensive system-level analysis of the GRN underlying the development of a single sensory neuron, the rod photoreceptor. Published by Elsevier Inc.

  18. Biological Significance of Photoreceptor Photocycle Length: VIVID Photocycle Governs the Dynamic VIVID-White Collar Complex Pool Mediating Photo-adaptation and Response to Changes in Light Intensity.

    Directory of Open Access Journals (Sweden)

    Arko Dasgupta

    2015-05-01

    Full Text Available Most organisms on earth sense light through the use of chromophore-bearing photoreceptive proteins with distinct and characteristic photocycle lengths, yet the biological significance of this adduct decay length is neither understood nor has been tested. In the filamentous fungus Neurospora crassa VIVID (VVD is a critical player in the process of photoadaptation, the attenuation of light-induced responses and the ability to maintain photosensitivity in response to changing light intensities. Detailed in vitro analysis of the photochemistry of the blue light sensing, FAD binding, LOV domain of VVD has revealed residues around the site of photo-adduct formation that influence the stability of the adduct state (light state, that is, altering the photocycle length. We have examined the biological significance of VVD photocycle length to photoadaptation and report that a double substitution mutant (vvdI74VI85V, previously shown to have a very fast light to dark state reversion in vitro, shows significantly reduced interaction with the White Collar Complex (WCC resulting in a substantial photoadaptation defect. This reduced interaction impacts photoreceptor transcription factor WHITE COLLAR-1 (WC-1 protein stability when N. crassa is exposed to light: The fast-reverting mutant VVD is unable to form a dynamic VVD-WCC pool of the size required for photoadaptation as assayed both by attenuation of gene expression and the ability to respond to increasing light intensity. Additionally, transcription of the clock gene frequency (frq is sensitive to changing light intensity in a wild-type strain but not in the fast photo-reversion mutant indicating that the establishment of this dynamic VVD-WCC pool is essential in general photobiology and circadian biology. Thus, VVD photocycle length appears sculpted to establish a VVD-WCC reservoir of sufficient size to sustain photoadaptation while maintaining sensitivity to changing light intensity. The great diversity

  19. In vivo absorption spectra of the two stable states of the Euglena photoreceptor photocycle.

    Science.gov (United States)

    Barsanti, Laura; Coltelli, Primo; Evangelista, Valtere; Passarelli, Vincenzo; Frassanito, Anna Maria; Vesentini, Nicoletta; Santoro, Fabrizio; Gualtieri, Paolo

    2009-01-01

    Euglena gracilis possesses a simple but sophisticated light detecting system, consisting of an eyespot formed by carotenoids globules and a photoreceptor. The photoreceptor of Euglena is characterized by optical bistability, with two stable states. In order to provide important and discriminating information on the series of structural changes that Euglena photoreceptive protein(s) undergoes inside the photoreceptor in response to light, we measured the in vivo absorption spectra of the two stable states A and B of photoreceptor photocycle. Data were collected using two different devices, i.e. a microspectrophotometer and a digital microscope. Our results show that the photocycle and the absorption spectra of the photoreceptor possess strong spectroscopic similarities with a rhodopsin-like protein. Moreover, the analysis of the absorption spectra of the two stable states of the photoreceptor and the absorption spectrum of the eyespot suggests an intriguing hypothesis for the orientation of microalgae toward light.

  20. Ocular anatomy and retinal photoreceptors in a skink, the sleepy lizard (Tiliqua rugosa).

    Science.gov (United States)

    New, Shaun T D; Hemmi, Jan M; Kerr, Gregory D; Bull, C Michael

    2012-10-01

    The Australian sleepy lizard (Tiliqua rugosa) is a large day-active skink which occupies stable overlapping home ranges and maintains long-term monogamous relationships. Its behavioral ecology has been extensively studied, making the sleepy lizard an ideal model for investigation of the lizard visual system and its specializations, for which relatively little is known. We examine the morphology, density, and distribution of retinal photoreceptors and describe the anatomy of the sleepy lizard eye. The sleepy lizard retina is composed solely of photoreceptors containing oil droplets, a characteristic of cones. Two groups could be distinguished; single cones and double cones, consistent with morphological descriptions of photoreceptors in other diurnal lizards. Although all photoreceptors were cone-like in morphology, a subset of photoreceptors displayed immunoreactivity to rhodopsin-the visual pigment of rods. This finding suggests that while the morphological properties of rod photoreceptors have been lost, photopigment protein composition has been conserved during evolutionary history.

  1. Effect of Purified Murine NGF on Isolated Photoreceptors of a Rodent Developing Retinitis Pigmentosa

    Science.gov (United States)

    Rocco, Maria Luisa; Balzamino, Bijorn Omar; Petrocchi Passeri, Pamela; Micera, Alessandra; Aloe, Luigi

    2015-01-01

    A number of different studies have shown that neurotrophins, including nerve growth factor (NGF) support the survival of retinal ganglion neurons during a variety if insults. Recently, we have reported that that eye NGF administration can protect also photoreceptor degeneration in a mice and rat with inherited retinitis pigmentosa. However, the evidence that NGF acts directly on photoreceptors and that other retinal cells mediate the NGF effect could not be excluded. In the present study we have isolated retinal cells from rats with inherited retinitis pigmentosa (RP) during the post-natal stage of photoreceptor degenerative. In presence of NGF, these cells are characterized by enhanced expression of NGF-receptors and rhodopsin, the specific marker of photoreceptor and better cell survival, as well as neuritis outgrowth. Together these observations support the hypothesis that NGF that NGF acts directly on photoreceptors survival and prevents photoreceptor degeneration as previously suggested by in vivo studies. PMID:25897972

  2. Usherin is required for maintenance of retinal photoreceptors and normal development of cochlear hair cells

    OpenAIRE

    2007-01-01

    Usher syndrome type IIA (USH2A), characterized by progressive photoreceptor degeneration and congenital moderate hearing loss, is the most common subtype of Usher syndrome. In this article, we show that the USH2A protein, also known as usherin, is an exceptionally large (≈600-kDa) matrix protein expressed specifically in retinal photoreceptors and developing cochlear hair cells. In mammalian photoreceptors, usherin is localized to a spatially restricted membrane microdomain at the apical inne...

  3. Pineal photoreceptor cells are required for maintaining the circadian rhythms of behavioral visual sensitivity in zebrafish.

    Directory of Open Access Journals (Sweden)

    Xinle Li

    Full Text Available In non-mammalian vertebrates, the pineal gland functions as the central pacemaker that regulates the circadian rhythms of animal behavior and physiology. We generated a transgenic zebrafish line [Tg(Gnat2:gal4-VP16/UAS:nfsB-mCherry] in which the E. coli nitroreductase is expressed in pineal photoreceptor cells. In developing embryos and young adults, the transgene is expressed in both retinal and pineal photoreceptor cells. During aging, the expression of the transgene in retinal photoreceptor cells gradually diminishes. By 8 months of age, the Gnat2 promoter-driven nitroreductase is no longer expressed in retinal photoreceptor cells, but its expression in pineal photoreceptor cells persists. This provides a tool for selective ablation of pineal photoreceptor cells, i.e., by treatments with metronidazole. In the absence of pineal photoreceptor cells, the behavioral visual sensitivity of the fish remains unchanged; however, the circadian rhythms of rod and cone sensitivity are diminished. Brief light exposures restore the circadian rhythms of behavioral visual sensitivity. Together, the data suggest that retinal photoreceptor cells respond to environmental cues and are capable of entraining the circadian rhythms of visual sensitivity; however, they are insufficient for maintaining the rhythms. Cellular signals from the pineal photoreceptor cells may be required for maintaining the circadian rhythms of visual sensitivity.

  4. Red Emission of Eu(Ⅲ) Complex Based on 1-(7-(tert-butyl)-9-ethyl-9H-carbazol-2-yl)-4,4,4-trifluorobutane-1,3-dione Excited by Blue Light

    Institute of Scientific and Technical Information of China (English)

    Sheng-gui Liu; Wen-yi Su; Rong-kai Pan; Xiao-ping Zhou

    2012-01-01

    A new Eu(Ⅲ) complex,EuL3(phen),was synthesized,where L is the abbreviation of deprotonated 1-(7-(tert-butyl)-9-ethyl-9H-carbazol-2-yl)-4,4,4-trifluorobutane-1,3-dione (HL),phen is the abbreviation of 1,10-phenanthroline.The Eu(Ⅲ) complex was characterized by element analysis,IR,1H NMR,UV-visible absorption spectroscopy,thermogravimetric analysis (TGA),and photoluminescence measurements (PL).TGA shows that thermal stability of the complex is up to 325 ℃.PL measurement indicates that the Eu(Ⅲ) complex exhibits intense red-emission and extends their excitation bands to visible region.LEDs device was successfully fabricated by precoating complex EuL3(phen) onto 460 nm blue-emitting InGaN chip.The emission of device shows that the complex can act as red phosphor in combination with 460 nm blue-emitting chips.This europium complex based on 1-(7-(tert-butyl)-9-ethyl-9H-carbazol-2-yl)-4,4,4-trifluorobutane-1,3-dione is a kind of interesting red-emitting material excited by blue light,which could avoid the damage of excitation by UV light.

  5. Clinical application of implantation of blue light-filtering aspheric intraocular lens by micro incision%微切口预装式蓝光滤过非球面人工晶状体临床应用

    Institute of Scientific and Technical Information of China (English)

    刘汝瑜; 宋慧; 汤欣; 魏荫娟

    2015-01-01

    Objective To compare the surgically induced astigmatism (SIA) of 2.0mm coaxial microincision cataract surgery (MICS) with 3.0mm small-incision cataract surgery (SICS) with blue light-filtering aspheric intraocular lens (IOL) implantation.Methods Retrospective case series of 48 cataract eyes undertaken phacoemulsification and IOL implantation from October 2012 to January 2013.MICS:26 eyes with 1-piece blue light-filtering aspheric intraocular lens by micro incision (iSert1,HOYA);SICS:22 eyes with 3-piece blue light-filtering aspheric intraocular lens by small incision (PY60AD,HOYA).Anterior chamber depth after mydriasis,corneal astigmatism,tilt and deviation of IOLs were measured using Scheimpflug system (Pentacam,Oculus) and analyzed with Image-pro plus 6.0 software.Slit lamp anterior segment photography and photoshop7.0 analyzed IOL rotation.Follow up was I week and 1 month.Results A significant SIA difference was found 1 week after surgery (P <0.05),no significant difference was found 1 month after surgery (P >0.05).With dilated pupil,there was a significant difference a month after surgery (P <0.05).No significant difference was found 1 week after surgery (P >0.05).Deviation,tilt and rotation of IOLs between the two groups showed no statistical significance (P >0.05).Conclusions Preloaded blue light-filtering aspheric intraocular lens by micro incision causes smaller SIA,is favor for visual recovery in short-term postoeration.%目的 观察2.0 mm同轴微切口白内障超声乳化(microincision cataract surgery,MICS)吸除术后植入微切口预装式蓝光滤过非球面人工晶状体(IOL)的手术源性散光(surgically induced astigmatism,SIA)及囊袋内稳定性,并与传统3.0 mm小切口白内障超声乳化(small-incision cataract surgery,SICS)手术进行比较.方法 回顾性系列病例研究.回顾性分析天津市眼科医院白内障中心于2012年10月至2013年1月白内障患者48只眼行超声乳化白

  6. Sonophotocatalytic degradation of trypan blue and vesuvine dyes in the presence of blue light active photocatalyst of Ag3PO4/Bi2S3-HKUST-1-MOF: Central composite optimization and synergistic effect study.

    Science.gov (United States)

    Mosleh, S; Rahimi, M R; Ghaedi, M; Dashtian, K

    2016-09-01

    An efficient simultaneous sonophotocatalytic degradation of trypan blue (TB) and vesuvine (VS) using Ag3PO4/Bi2S3-HKUST-1-MOF as a novel visible light active photocatalyst was carried out successfully in a continuous flow-loop reactor equipped to blue LED light. Ag3PO4/Bi2S3-HKUST-1-MOF with activation ability under blue light illumination was synthesized and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), photoluminescence (PL) and diffuse reflectance spectra (DRS). The effect of operational parameters such as the initial TB and VS concentration (5-45mg/L), flow rate (30-110mL/min), irradiation and sonication time (10-30min), pH (3-11) and photocatalyst dosage (0.15-0.35g/L) has been investigated and optimized using central composite design (CCD) combined with desirability function (DF). Maximum sonophotodegradation percentage (98.44% and 99.36% for TB and VS, respectively) was found at optimum condition set as: 25mg/L of each dye, 70mL/min of solution flow rate, 25min of irradiation and sonication time, pH 6 and 0.25g/L of photocatalyst dosage. At optimum conditions, synergistic index value was obtained 2.53 that indicated the hybrid systems including ultrasound irradiation and photocatalysis have higher efficiency compared with sum of the individual processes.

  7. 预防性和治疗性二极管蓝光照射防治极低出生体质量儿高胆红素血症的疗效比较%Comparison of Efficacy of Prophylactic and Therapeutic Blue-Light Light Emitting Diode Phototherapy for Management of Hyperbilirubinemia in Very Low Birth Weight Infants

    Institute of Scientific and Technical Information of China (English)

    舒桂华; 徐翔; 严语; 朱玲玲

    2014-01-01

    of serum bilirubin,withdrawal time of jaundice,incidence rate of hyperbilirubinemia (serum bilirubin > 1 7 1 .0μmol/L) and side effects (fever, diarrhea, skin rash, hypocalcemia,anemia,bronzing)were observed.The study protocol was approved by the Ethical Review Board of Investigation in Human Being of Clinic Medical College of Yangzhou University.Informed consent was obtained from each participants′parents.There was no significant difference in general clinical data between two groups (P>0.05).Results The duration of phototherapy in the prophylactic group was longer than that of the treatment group,but this difference was not statistically significant(P>0.05). Whereas the peak levels of serum bilirubin and withdrawal time of jaundice in the prophylactic group were obviously lower than those of the treatment group(P0.05).Conclusions For the management of hyperbilirubinemia in VLBWI,the effect of prophylactic blue-light LED phototherapy appears to have advantage over therapeutic blue-light LED phototherapy.It has value of high efficiency and safety ,may be worthy of application widely.

  8. Role of kinesin heavy chain in Crumbs localization along the rhabdomere elongation in Drosophila photoreceptor.

    Directory of Open Access Journals (Sweden)

    Garrett P League

    Full Text Available BACKGROUND: Crumbs (Crb, a cell polarity gene, has been shown to provide a positional cue for the extension of the apical membrane domain, adherens junction (AJ, and rhabdomere along the growing proximal-distal axis during Drosophila photoreceptor morphogenesis. In developing Drosophila photoreceptors, a stabilized microtubule structure was discovered and its presence was linked to polarity protein localization. It was therefore hypothesized that the microtubules may provide trafficking routes for the polarity proteins during photoreceptor morphogenesis. This study has examined whether Kinesin heavy chain (Khc, a subunit of the microtubule-based motor Kinesin-1, is essential in polarity protein localization in developing photoreceptors. METHODOLOGY/PRINCIPAL FINDINGS: Because a genetic interaction was found between crb and khc, Crb localization was examined in the developing photoreceptors of khc mutants. khc was dispensable during early eye differentiation and development. However, khc mutant photoreceptors showed a range of abnormalities in the apical membrane domain depending on the position along the proximal-distal axis in pupal photoreceptors. The khc mutant showed a progressive mislocalization in the apical domain along the distal-proximal axis during rhabdomere elongation. The khc mutation also led to a similar progressive defect in the stabilized microtubule structures, strongly suggesting that Khc is essential for microtubule structure and Crb localization during distal to proximal rhabdomere elongation in pupal morphogenesis. This role of Khc in apical domain control was further supported by khc's gain-of-function phenotype. Khc overexpression in photoreceptors caused disruption of the apical membrane domain and the stabilized microtubules in the developing photoreceptors. CONCLUSIONS/SIGNIFICANCE: In summary, we examined the role of khc in the regulation of the apical Crb domain in developing photoreceptors. Since the rhabdomeres in

  9. Calcium-dependent potassium current in barnacle photoreceptor

    OpenAIRE

    1981-01-01

    When barnacle lateral eye photoreceptors are depolarized to membrane potentials of 0 to +50 mV in the dark, the plot of outward current through the cell membrane against time has two distinct maxima. The first maximum occurs 5-10 ms after the depolarization began. The current then decays to a minimum at approximately 500 ms after the onset of depolarization, and then increases to a second maximum 4-6 s after the depolarization began. If depolarization is maintained, the current again decays t...

  10. Constitutively active UVR8 photoreceptor variant in Arabidopsis

    OpenAIRE

    2013-01-01

    Sunlight is an essential environmental factor for photosynthetic plants and ultimately for life on Earth, which is sustained through plants as fundamental source of food. However, plants have a love/hate relationship with sunlight and must be protected from potentially harmful UV-B radiation. The UV-B photoreceptor UVR8 is of great importance in mounting UV-protective responses and thus for survival in sunlight. Based on our understanding of UVR8 signaling, we have engineered a UVR8 variant t...

  11. Light adaptation and the evolution of vertebrate photoreceptors.

    Science.gov (United States)

    Morshedian, Ala; Fain, Gordon L

    2017-07-15

    Lamprey are cyclostomes, a group of vertebrates that diverged from lines leading to jawed vertebrates (including mammals) in the late Cambrian, 500 million years ago. It may therefore be possible to infer properties of photoreceptors in early vertebrate progenitors by comparing lamprey to other vertebrates. We show that lamprey rods and cones respond to light much like rods and cones in amphibians and mammals. They operate over a similar range of light intensities and adapt to backgrounds and bleaches nearly identically. These correspondences are pervasive and detailed; they argue for the presence of rods and cones very early in the evolution of vertebrates with properties much like those of rods and cones in existing vertebrate species. The earliest vertebrates were agnathans - fish-like organisms without jaws, which first appeared near the end of the Cambrian radiation. One group of agnathans became cyclostomes, which include lamprey and hagfish. Other agnathans gave rise to jawed vertebrates or gnathostomes, the group including all other existing vertebrate species. Because cyclostomes diverged from other vertebrates 500 million years ago, it may be possible to infer some of the properties of the retina of early vertebrate progenitors by comparing lamprey to other vertebrates. We have previously shown that rods and cones in lamprey respond to light much like photoreceptors in other vertebrates and have a similar sensitivity. We now show that these affinities are even closer. Both rods and cones adapt to background light and to bleaches in a manner almost identical to other vertebrate photoreceptors. The operating range in darkness is nearly the same in lamprey and in amphibian or mammalian rods and cones; moreover background light shifts response-intensity curves downward and to the right over a similar range of ambient intensities. Rods show increment saturation at about the same intensity as mammalian rods, and cones never saturate. Bleaches decrease

  12. Measurement of Photon Statistics with Live Photoreceptor Cells

    CERN Document Server

    Sim, Nigel; Bessarab, Dmitri; Jones, C Michael; Krivitsky, Leonid

    2012-01-01

    We analyzed the electrophysiological response of an isolated rod photoreceptor of Xenopus laevis under stimulation by coherent and pseudo-thermal light sources. Using the suction electrode technique for single cell recordings and a fiber optics setup for light delivery allowed measurements of the major statistical characteristics of the rod response. The results indicate differences in average responses of rod cells to coherent and pseudo-thermal light of the same intensity and also differences in signal-to-noise ratios and second order intensity correlation functions. These findings should be relevant for interdisciplinary studies in applications of quantum optics in biology.

  13. Ionic currents underlying difference in light response between type A and type B photoreceptors.

    Science.gov (United States)

    Blackwell, K T

    2006-05-01

    In Hermissenda crassicornis, the memory of light associated with turbulence is stored as changes in intrinsic and synaptic currents in both type A and type B photoreceptors. These photoreceptor types exhibit qualitatively different responses to light and current injection, and these differences shape the spatiotemporal firing patterns that control behavior. Thus the objective of the study was to identify the mechanisms underlying these differences. The approach was to develop a type B model that reproduced characteristics of type B photoreceptors recorded in vitro, and then to create a type A model by modifying a select number of ionic currents. Comparison of type A models with characteristics of type A photoreceptors recorded in vitro revealed that type A and type B photoreceptors have five main differences, three that have been characterized experimentally and two that constitute hypotheses to be tested with experiments in the future. The three differences between type A and type B photoreceptors previously characterized include the inward rectifier current, the fast sodium current, and conductance of calcium-dependent and transient potassium channels. Two additional changes were required to produce a type A photoreceptor model. The very fast firing frequency observed during the first second after light onset required a faster time constant of activation of the delayed rectifier. The fast spike adaptation required a fast, noninactivating calcium-dependent potassium current. Because these differences between type A and type B photoreceptors have not been confirmed in comparative experiments, they constitute hypotheses to be tested with future experiments.

  14. Large variation among photoreceptors as the basis of visual flexibility in the common backswimmer

    Science.gov (United States)

    Immonen, Esa-Ville; Ignatova, Irina; Gislen, Anna; Warrant, Eric; Vähäsöyrinki, Mikko; Weckström, Matti; Frolov, Roman

    2014-01-01

    The common backswimmer, Notonecta glauca, uses vision by day and night for functions such as underwater prey animal capture and flight in search of new habitats. Although previous studies have identified some of the physiological mechanisms facilitating such flexibility in the animal's vision, neither the biophysics of Notonecta photoreceptors nor possible cellular adaptations are known. Here, we studied Notonecta photoreceptors using patch-clamp and intracellular recording methods. Photoreceptor size (approximated by capacitance) was positively correlated with absolute sensitivity and acceptance angles. Information rate measurements indicated that large and more sensitive photoreceptors performed better than small ones. Our results suggest that backswimmers are adapted for vision in both dim and well-illuminated environments by having open-rhabdom eyes with large intrinsic variation in absolute sensitivity among photoreceptors, exceeding those found in purely diurnal or nocturnal species. Both electrophysiology and microscopic analysis of retinal structure suggest two retinal subsystems: the largest peripheral photoreceptors provide vision in dim light and the smaller peripheral and central photoreceptors function primarily in sunlight, with light-dependent pigment screening further contributing to adaptation in this system by dynamically recruiting photoreceptors with varying sensitivity into the operational pool. PMID:25274359

  15. Evidence for dynamic network regulation of Drosophila photoreceptor function from mutants lacking the neurotransmitter histamine

    Directory of Open Access Journals (Sweden)

    An eDau

    2016-03-01

    Full Text Available Synaptic feedback from interneurons to photoreceptors can help to optimize visual information flow by balancing its allocation on retinal pathways under changing light conditions. But little is known about how this critical network operation is regulated dynamically. Here, we investigate this question by comparing signaling properties and performance of wild-type Drosophila R1-R6 photoreceptors to those of the hdcJK910 mutant, which lacks the neurotransmitter histamine and therefore cannot transmit information to interneurons. Recordings show that hdcJK910 photoreceptors sample similar amounts of information from naturalistic stimulation to wild-type photoreceptors, but this information is packaged in smaller responses, especially under bright illumination. Analyses reveal how these altered dynamics primarily resulted from network overload that affected hdcJK910 photoreceptors in two ways. First, the missing inhibitory histamine input to interneurons almost certainly depolarized them irrevocably, which in turn increased their excitatory feedback to hdcJK910 R1-R6s. This tonic excitation depolarized the photoreceptors to artificially high potentials, reducing their operational range. Second, rescuing histamine input to interneurons in hdcJK910 mutant also restored their normal phasic feedback modulation to R1-R6s, causing photoreceptor output to accentuate dynamic intensity differences at bright illumination, similar to the wild-type. These results provide mechanistic explanations of how synaptic feedback connections optimize information packaging in photoreceptor output and novel insight into the operation and design of dynamic network regulation of sensory neurons.

  16. Evidence for Dynamic Network Regulation of Drosophila Photoreceptor Function from Mutants Lacking the Neurotransmitter Histamine.

    Science.gov (United States)

    Dau, An; Friederich, Uwe; Dongre, Sidhartha; Li, Xiaofeng; Bollepalli, Murali K; Hardie, Roger C; Juusola, Mikko

    2016-01-01

    Synaptic feedback from interneurons to photoreceptors can help to optimize visual information flow by balancing its allocation on retinal pathways under changing light conditions. But little is known about how this critical network operation is regulated dynamically. Here, we investigate this question by comparing signaling properties and performance of wild-type Drosophila R1-R6 photoreceptors to those of the hdc (JK910) mutant, which lacks the neurotransmitter histamine and therefore cannot transmit information to interneurons. Recordings show that hdc (JK910) photoreceptors sample similar amounts of information from naturalistic stimulation to wild-type photoreceptors, but this information is packaged in smaller responses, especially under bright illumination. Analyses reveal how these altered dynamics primarily resulted from network overload that affected hdc (JK910) photoreceptors in two ways. First, the missing inhibitory histamine input to interneurons almost certainly depolarized them irrevocably, which in turn increased their excitatory feedback to hdc (JK910) R1-R6s. This tonic excitation depolarized the photoreceptors to artificially high potentials, reducing their operational range. Second, rescuing histamine input to interneurons in hdc (JK910) mutant also restored their normal phasic feedback modulation to R1-R6s, causing photoreceptor output to accentuate dynamic intensity differences at bright illumination, similar to the wild-type. These results provide mechanistic explanations of how synaptic feedback connections optimize information packaging in photoreceptor output and novel insight into the operation and design of dynamic network regulation of sensory neurons.

  17. Electrical coupling of neuro-ommatidial photoreceptor cells in the blowfly

    NARCIS (Netherlands)

    Hateren, J.H. van

    1986-01-01

    A new method of microstimulation of the blowfly eye using corneal neutralization was applied to the 6 peripheral photoreceptor cells (R1-R6) connected to one neuro-ommatidium (and thus looking into the same direction), whilst the receptor potential of a dark-adapted photoreceptor cell was recorded b

  18. Cellular elements for seeing in the dark: voltage-dependent conductances in cockroach photoreceptors

    Directory of Open Access Journals (Sweden)

    Salmela Iikka

    2012-08-01

    Full Text Available Abstract Background The importance of voltage-dependent conductances in sensory information processing is well-established in insect photoreceptors. Here we present the characterization of electrical properties in photoreceptors of the cockroach (Periplaneta americana, a nocturnal insect with a visual system adapted for dim light. Results Whole-cell patch-clamped photoreceptors had high capacitances and input resistances, indicating large photosensitive rhabdomeres suitable for efficient photon capture and amplification of small photocurrents at low light levels. Two voltage-dependent potassium conductances were found in the photoreceptors: a delayed rectifier type (KDR and a fast transient inactivating type (KA. Activation of KDR occurred during physiological voltage responses induced by light stimulation, whereas KA was nearly fully inactivated already at the dark resting potential. In addition, hyperpolarization of photoreceptors activated a small-amplitude inward-rectifying (IR current mediated at least partially by chloride. Computer simulations showed that KDR shapes light responses by opposing the light-induced depolarization and speeding up the membrane time constant, whereas KA and IR have a negligible role in the majority of cells. However, larger KA conductances were found in smaller and rapidly adapting photoreceptors, where KA could have a functional role. Conclusions The relative expression of KA and KDR in cockroach photoreceptors was opposite to the previously hypothesized framework for dark-active insects, necessitating further comparative work on the conductances. In general, the varying deployment of stereotypical K+ conductances in insect photoreceptors highlights their functional flexibility in neural coding.

  19. On the Effective Optical Density of the Pupil Mechanism in Fly Photoreceptors

    NARCIS (Netherlands)

    Roebroek, Jos G.H.; Stavenga, Doekele G.

    1990-01-01

    A simple electrophysiological method is described for determining the effective optical density of the intracellular pupil mechanism of insect photoreceptor ceils. The method depends on the fact that the photoreceptors can not only be illuminated in the normal, orthodromic way, but also antidromical

  20. Photoreceptor processing speed and input resistance changes during light adaptation correlate with spectral class in the bumblebee, Bombus impatiens.

    Directory of Open Access Journals (Sweden)

    Peter Skorupski

    Full Text Available Colour vision depends on comparison of signals from photoreceptors with different spectral sensitivities. However, response properties of photoreceptor cells may differ in ways other than spectral tuning. In insects, for example, broadband photoreceptors, with a major sensitivity peak in the green region of the spectrum (>500 nm, drive fast visual processes, which are largely blind to chromatic signals from more narrowly-tuned photoreceptors with peak sensitivities in the blue and UV regions of the spectrum. In addition, electrophysiological properties of the photoreceptor membrane may result in differences in response dynamics of photoreceptors of similar spectral class between species, and different spectral classes within a species. We used intracellular electrophysiological techniques to investigate response dynamics of the three spectral classes of photoreceptor underlying trichromatic colour vision in the bumblebee, Bombus impatiens, and we compare these with previously published data from a related species, Bombus terrestris. In both species, we found significantly faster responses in green, compared with blue- or UV-sensitive photoreceptors, although all 3 photoreceptor types are slower in B. impatiens than in B. terrestris. Integration times for light-adapted B. impatiens photoreceptors (estimated from impulse response half-width were 11.3 ± 1.6 ms for green photoreceptors compared with 18.6 ± 4.4 ms and 15.6 ± 4.4 for blue and UV, respectively. We also measured photoreceptor input resistance in dark- and light-adapted conditions. All photoreceptors showed a decrease in input resistance during light adaptation, but this decrease was considerably larger (declining to about 22% of the dark value in green photoreceptors, compared to blue and UV (41% and 49%, respectively. Our results suggest that the conductances associated with light adaptation are largest in green photoreceptors, contributing to their greater temporal processing speed

  1. Novel Methodology for Creating Macaque Retinas with Sortable Photoreceptors and Ganglion Cells

    Directory of Open Access Journals (Sweden)

    Shreyasi Choudhury

    2016-12-01

    Full Text Available Purpose: The ability to generate macaque retinas with sortable cell populations would be of great benefit to both basic and translational studies of the primate retina. The purpose of our study was therefore to develop methods to achieve this goal by selectively labeling, in life, photoreceptors (PRs and retinal ganglion cells (RGCs with separate fluorescent markers. Methods: Labeling of macaque (Macaca fascicularis PRs and RGCs was accomplished by subretinal delivery of AAV5-hGRK1-GFP, and retrograde transport of micro-ruby™ from the lateral geniculate nucleus, respectively. Retinas were anatomically separated into different regions. Dissociation conditions were optimized, and cells from each region underwent fluorescent activated cell sorting (FACS. Expression of retinal cell type- specific genes was assessed by quantitative real-time PCR to characterize isolated cell populations. Results: We show that macaque PRs and RGCs can be simultaneously labeled in-life and enriched populations isolated by FACS. Recovery from different retinal regions indicated efficient isolation/enrichment for PRs and RGCs, with the macula being particularly amendable to this technique. Conclusions: The methods and materials presented here allow for the identification of novel reagents designed to target retinal ganglion cells and/or photoreceptors in a species that is phylogenetically and anatomically similar to human. These techniques will enable screening of intravitreally- delivered AAV capsid libraries for variants with increased tropism for PRs and/or RGCs and the evaluation of vector tropism and/or cellular promoter activity of gene therapy vectors in a clinically relevant species.

  2. Eyes shut homolog is required for maintaining the ciliary pocket and survival of photoreceptors in zebrafish

    Directory of Open Access Journals (Sweden)

    Miao Yu

    2016-11-01

    Full Text Available Mutations in the extracellular matrix protein eyes shut homolog (EYS cause photoreceptor degeneration in patients with retinitis pigmentosa 25 (RP25. Functions of EYS remain poorly understood, due in part to the lack of an EYS gene in mouse. We investigated the localization of vertebrate EYS proteins and engineered loss-of-function alleles in zebrafish. Immunostaining indicated that EYS localized near the connecting cilium/transition zone in photoreceptors. EYS also strongly localized to the cone outer segments and weakly to the rod outer segments and cone terminals in primate retinas. Analysis of mutant EYS zebrafish revealed disruption of the ciliary pocket in cone photoreceptors, indicating that EYS is required for maintaining the integrity of the ciliary pocket lumen. Mutant zebrafish exhibited progressive loss of cone and rod photoreceptors. Our results indicate that EYS protein localization is species-dependent and that EYS is required for maintaining ciliary pocket morphology and survival of photoreceptors in zebrafish.

  3. Bat eyes have ultraviolet-sensitive cone photoreceptors.

    Directory of Open Access Journals (Sweden)

    Brigitte Müller

    Full Text Available Mammalian retinae have rod photoreceptors for night vision and cone photoreceptors for daylight and colour vision. For colour discrimination, most mammals possess two cone populations with two visual pigments (opsins that have absorption maxima at short wavelengths (blue or ultraviolet light and long wavelengths (green or red light. Microchiropteran bats, which use echolocation to navigate and forage in complete darkness, have long been considered to have pure rod retinae. Here we use opsin immunohistochemistry to show that two phyllostomid microbats, Glossophaga soricina and Carollia perspicillata, possess a significant population of cones and express two cone opsins, a shortwave-sensitive (S opsin and a longwave-sensitive (L opsin. A substantial population of cones expresses S opsin exclusively, whereas the other cones mostly coexpress L and S opsin. S opsin gene analysis suggests ultraviolet (UV, wavelengths <400 nm sensitivity, and corneal electroretinogram recordings reveal an elevated sensitivity to UV light which is mediated by an S cone visual pigment. Therefore bats have retained the ancestral UV tuning of the S cone pigment. We conclude that bats have the prerequisite for daylight vision, dichromatic colour vision, and UV vision. For bats, the UV-sensitive cones may be advantageous for visual orientation at twilight, predator avoidance, and detection of UV-reflecting flowers for those that feed on nectar.

  4. Response Function of the Crayfish Caudal Photoreceptor to Hydrodynamic Stimuli

    Science.gov (United States)

    Breite, Sally; Bahar, Sonya; Neiman, Alexander; Moss, Frank

    2002-03-01

    In its abdominal 6th ganglion the crayfish houses 2 light-sensitive neurons (caudal photoreceptors, or CPRs). It is known that these neurons work in tandem with a mechanosensory system of tiny hairs spread across the tailfan, which make synaptic contact with the photoreceptors. A stochastic resonance effect has been shown in this system in which light enhances the transduction of a weak, periodic mechanosensory (hydrodynamic) stimulus. It is not known, however, whether an optimal response from the CPR is induced by a single sine wave cycle or some other waveform. We have experimentally investigated this favorable waveform by driving a tailfan preparation with mechanical 10 Hz correlated Ornstein-Uhlenbeck noise and calculating the response function from the spike-triggered average of the applied noise waveform. We will discuss differences in the shape of the optimal waveform under dark and light conditions, as well as what seems to be a noticeable difference in the magnitude of the animals' response to a noisy stimulus in comparison with a periodic stimulus.

  5. Antagonistic functions of two stardust isoforms in Drosophila photoreceptor cells.

    Science.gov (United States)

    Bulgakova, Natalia A; Rentsch, Michaela; Knust, Elisabeth

    2010-11-15

    Membrane-associated guanylate kinases (MAGUKs) are scaffolding proteins that organize supramolecular protein complexes, thereby partitioning the plasma membrane into spatially and functionally distinct subdomains. Their modular organization is ideally suited to organize protein complexes with cell type- or stage-specific composition, or both. Often more than one MAGUK isoform is expressed by one gene in the same cell, yet very little is known about their individual in vivo functions. Here, we show that two isoforms of Drosophila stardust, Sdt-H (formerly called Sdt-B2) and Sdt-D, which differ in their N terminus, are expressed in adult photoreceptors. Both isoforms associate with Crumbs and PATJ, constituents of the conserved Crumbs-Stardust complex. However, they form distinct complexes, localized at the stalk, a restricted region of the apical plasma membrane. Strikingly, Sdt-H and Sdt-D have antagonistic functions. While Sdt-H overexpression increases stalk membrane length and prevents light-dependent retinal degeneration, Sdt-D overexpression reduces stalk length and enhances light-dependent retinal degeneration. These results suggest that a fine-tuned balance of different Crumbs complexes regulates photoreceptor homeostasis.

  6. Synthesis of docosahexaenoic acid from eicosapentaenoic acid in retina neurons protects photoreceptors from oxidative stress.

    Science.gov (United States)

    Simón, María Victoria; Agnolazza, Daniela L; German, Olga Lorena; Garelli, Andrés; Politi, Luis E; Agbaga, Martin-Paul; Anderson, Robert E; Rotstein, Nora P

    2016-03-01

    Oxidative stress is involved in activating photoreceptor death in several retinal degenerations. Docosahexaenoic acid (DHA), the major polyunsaturated fatty acid in the retina, protects cultured retina photoreceptors from apoptosis induced by oxidative stress and promotes photoreceptor differentiation. Here, we investigated whether eicosapentaenoic acid (EPA), a metabolic precursor to DHA, had similar effects and whether retinal neurons could metabolize EPA to DHA. Adding EPA to rat retina neuronal cultures increased opsin expression and protected photoreceptors from apoptosis induced by the oxidants paraquat and hydrogen peroxide (H2 O2 ). Palmitic, oleic, and arachidonic acids had no protective effect, showing the specificity for DHA. We found that EPA supplementation significantly increased DHA percentage in retinal neurons, but not EPA percentage. Photoreceptors and glial cells expressed Δ6 desaturase (FADS2), which introduces the last double bond in DHA biosynthetic pathway. Pre-treatment of neuronal cultures with CP-24879 hydrochloride, a Δ5/Δ6 desaturase inhibitor, prevented EPA-induced increase in DHA percentage and completely blocked EPA protection and its effect on photoreceptor differentiation. These results suggest that EPA promoted photoreceptor differentiation and rescued photoreceptors from oxidative stress-induced apoptosis through its elongation and desaturation to DHA. Our data show, for the first time, that isolated retinal neurons can synthesize DHA in culture. Docosahexaenoic acid (DHA), the major polyunsaturated fatty acid in retina photoreceptors, and its precursor, eicosapentaenoic acid (EPA) have multiple beneficial effects. Here, we show that retina neurons in vitro express the desaturase FADS2 and can synthesize DHA from EPA. Moreover, addition of EPA to these cultures protects photoreceptors from oxidative stress and promotes their differentiation through its metabolization to DHA.

  7. Thrombin generation, ProC(®)Global, prothrombin time and activated partial thromboplastin time in thawed plasma stored for seven days and after methylene blue/light pathogen inactivation.

    Science.gov (United States)

    Thiele, Thomas; Hron, Gregor; Kellner, Sarah; Wasner, Christina; Westphal, Antje; Warkentin, Theodore E; Greinacher, Andreas; Selleng, Kathleen

    2016-01-01

    Methylene blue pathogen inactivation and storage of thawed plasma both lead to changes in the activity of several clotting factors. We investigated how this translates into a global loss of thrombin generation potential and alterations in the protein C pathway. Fifty apheresis plasma samples were thawed and each divided into three subunits. One subunit was stored for 7 days at 4 °C, one was stored for 7 days at 22 °C and one was stored at 4 °C after methylene blue/light treatment. Thrombin generation parameters, ProC(®)Global-NR, prothrombin time and activated partial thromboplastin time were assessed on days 0 and 7. The velocity of thrombin generation increased significantly after methylene blue treatment (increased thrombin generation rate; time to peak decreased) and decreased after storage (decreased thrombin generation rate and peak thrombin; increased lag time and time to peak). The endogenous thrombin generation potential remained stable after methylene blue treatment and storage at 4 °C. Methylene blue treatment and 7 days of storage at 4 °C activated the protein C pathway, whereas storage at room temperature and storage after methylene blue treatment decreased the functional capacity of the protein C pathway. Prothrombin time and activated partial thromboplastin time showed only modest alterations. The global clotting capacity of thawed plasma is maintained at 4 °C for 7 days and directly after methylene blue treatment of thawed plasma. Thrombin generation and ProC(®)Global are useful tools for investigating the impact of pathogen inactivation and storage on the clotting capacity of therapeutic plasma preparations.

  8. Performance enhancement of blue light-emitting diodes with InGaN/GaN multi-quantum wells grown on Si substrates by inserting thin AlGaN interlayers

    Science.gov (United States)

    Kimura, Shigeya; Yoshida, Hisashi; Uesugi, Kenjiro; Ito, Toshihide; Okada, Aoi; Nunoue, Shinya

    2016-09-01

    We have grown blue light-emitting diodes (LEDs) having InGaN/GaN multi-quantum wells (MQWs) with thin AlyGa1-yN (0 transmission electron microscopy observations and three-dimensional atom probe analysis that 1-nm-thick interlayers with an AlN mole fraction of less than y = 0.3 were continuously formed between GaN barriers and InGaN wells, and that the AlN mole fraction up to y = 0.15 could be consistently controlled. The external quantum efficiency of the blue LED was enhanced in the low-current-density region (≤45 A/cm2) but reduced in the high-current-density region by the insertion of the thin Al0.15Ga0.85N interlayers in the MQWs. We also found that reductions in both forward voltage and wavelength shift with current were achieved by inserting the interlayers even though the inserted AlGaN layers had potential higher than that of the GaN barriers. The obtained peak wall-plug efficiency was 83% at room temperature. We suggest that the enhanced electroluminescence (EL) performance was caused by the introduction of polarization-induced hole carriers in the InGaN wells on the side adjacent to the thin AlGaN/InGaN interface and efficient electron carrier transport through multiple wells. This model is supported by temperature-dependent EL properties and band-diagram simulations. We also found that inserting the interlayers brought about a reduction in the Shockley-Read-Hall nonradiative recombination component, corresponding to the shrinkage of V-defects. This is another conceivable reason for the observed performance enhancement.

  9. Effects of Red and Blue Light with Different Ratios on Growth of Cherry Tomato Seedlings%不同比例红蓝光对樱桃番茄幼苗生长的影响

    Institute of Scientific and Technical Information of China (English)

    刘少梅; 王丽娟; 切岩祥和

    2015-01-01

    试验以50%R(红光)+50%B(蓝光)LED光质为对照,研究了30%R+70%B与70%R+30%B两种比例光质对樱桃番茄幼苗生长和光合特性的影响。试验表明:70%R+30%B处理下,樱桃番茄幼苗的株高、叶片展开度、植株干鲜重、叶绿素含量以及净光合速率等都最高,并且显著大于30%R+70%B和对照;30%R+70%B处理下,樱桃番茄幼苗的株高、叶绿素含量和叶片展开度最低,而其茎粗显著高于其他处理。结果表明,70%R+30%B处理更利于樱桃番茄幼苗的生长发育。%The effects of LED (light emitting diode) with 30%R (red light)+70% B (blue light)and 70% R+30% B light ratios on growth and photosynthetic characteristics of cherry tomato seedlings were studied compared with the control group with 50%R+50%B. The results show that under the conditions of 70%R+30%B, the plant height, leaf area, fresh and dry weights, chlorophyll content and photosynthesis were all the maximum and significantly higher than those of 30% R+70% B and the control. Under the conditions of 30%R+70%B, the plant height, chlorophyll content and leaf area were the lowest, while the stem diameter was significantly higher than that of others. It is concluded that 70% R+30% B was better for the growth of cherry tomato seedlings.

  10. Short wavelength light filtering by the natural human lens and IOLs -- implications for entrainment of circadian rhythm

    DEFF Research Database (Denmark)

    Brøndsted, Adam Elias; Lundeman, Jesper Holm; Kessel, Line

    2013-01-01

    Photoentrainment of circadian rhythm begins with the stimulation of melanopsin containing retinal ganglion cells that respond directly to blue light. With age, the human lens becomes a strong colour filter attenuating transmission of short wavelengths. The purpose of the study was to examine...

  11. Preservation of cone photoreceptors after a rapid yet transient degeneration and remodeling in cone-only Nrl-/- mouse retina.

    Science.gov (United States)

    Roger, Jerome E; Ranganath, Keerthi; Zhao, Lian; Cojocaru, Radu I; Brooks, Matthew; Gotoh, Norimoto; Veleri, Shobi; Hiriyanna, Avinash; Rachel, Rivka A; Campos, Maria Mercedes; Fariss, Robert N; Wong, Wai T; Swaroop, Anand

    2012-01-11

    Cone photoreceptors are the primary initiator of visual transduction in the human retina. Dysfunction or death of rod photoreceptors precedes cone loss in many retinal and macular degenerative diseases, suggesting a rod-dependent trophic support for cone survival. Rod differentiation and homeostasis are dependent on the basic motif leucine zipper transcription factor neural retina leucine zipper (NRL). The loss of Nrl (Nrl(-/-)) in mice results in a retina with predominantly S-opsin-containing cones that exhibit molecular and functional characteristics of wild-type cones. Here, we report that Nrl(-/-) retina undergoes a rapid but transient period of degeneration in early adulthood, with cone apoptosis, retinal detachment, alterations in retinal vessel structure, and activation and translocation of retinal microglia. However, cone degeneration stabilizes by 4 months of age, resulting in a thinner but intact outer nuclear layer with residual cones expressing S- and M-opsins and a preserved photopic electroretinogram. At this stage, microglia translocate back to the inner retina and reacquire a quiescent morphology. Gene profiling analysis during the period of transient degeneration reveals misregulation of genes related to stress response and inflammation, implying their involvement in cone death. The Nrl(-/-) mouse illustrates the long-term viability of cones in the absence of rods and retinal pigment epithelium defects in a rodless retina. We propose that Nrl(-/-) retina may serve as a model for elucidating mechanisms of cone homeostasis and degeneration that would be relevant to understanding diseases of the cone-dominant human macula.

  12. A new photosensory function for simple photoreceptors, the intrinsically photoresponsive neurons of the sea slug Onchidium

    Directory of Open Access Journals (Sweden)

    Tsukasa Gotow

    2009-12-01

    Full Text Available Simple photoreceptors, namely intrinsically light-sensitive neurons without microvilli and/or cilia, have long been known to exist in the central ganglia of crayfish, Aplysia, Onchidium, and Helix. These simple photoreceptors are not only first-order photosensory cells, but also second-order neurons (interneurons, relaying several kinds of sensory synaptic inputs. Another important issue is that the photoresponses of these simple photoreceptors show very slow kinetics and little adaptation. These characteristics suggest that the simple photoreceptors of the Onchidium have a function in non-image-forming vision, different from classical eye photoreceptors used for cording dynamic images of vision. The cited literature provides evidence that the depolarizing and hyperpolarizing photoresponses of simple photoreceptors play a role in the long-lasting potentiation of synaptic transmission of excitatory and inhibitory sensory inputs, and as well as in the potentiation and the suppression of the subsequent behavioral outputs. In short, we suggest that simple photoreceptors operate in the general potentiation of synaptic transmission and subsequent motor output; i.e., they perform a new photosensory function.

  13. Histamine Recycling Is Mediated by CarT, a Carcinine Transporter in Drosophila Photoreceptors.

    Science.gov (United States)

    Xu, Ying; An, Futing; Borycz, Jolanta A; Borycz, Janusz; Meinertzhagen, Ian A; Wang, Tao

    2015-12-01

    Histamine is an important chemical messenger that regulates multiple physiological processes in both vertebrate and invertebrate animals. Even so, how glial cells and neurons recycle histamine remains to be elucidated. Drosophila photoreceptor neurons use histamine as a neurotransmitter, and the released histamine is recycled through neighboring glia, where it is conjugated to β-alanine to form carcinine. However, how carcinine is then returned to the photoreceptor remains unclear. In an mRNA-seq screen for photoreceptor cell-enriched transporters, we identified CG9317, an SLC22 transporter family protein, and named it CarT (Carcinine Transporter). S2 cells that express CarT are able to take up carcinine in vitro. In the compound eye, CarT is exclusively localized to photoreceptor terminals. Null mutations of cart alter the content of histamine and its metabolites. Moreover, null cart mutants are defective in photoreceptor synaptic transmission and lack phototaxis. These findings reveal that CarT is required for histamine recycling at histaminergic photoreceptors and provide evidence for a CarT-dependent neurotransmitter trafficking pathway between glial cells and photoreceptor terminals.

  14. Generation of a genetically encoded marker of rod photoreceptor outer segment growth and renewal

    Directory of Open Access Journals (Sweden)

    John J. Willoughby

    2011-10-01

    Vertebrate photoreceptors are specialized light sensing neurons. The photoreceptor outer segment is a highly modified cilium where photons of light are transduced into a chemical and electrical signal. The outer segment has the typical cilary axoneme but, in addition, it has a large number of densely packed, stacked, intramembranous discs. The molecular and cellular mechanisms that contribute to vertebrate photoreceptor outer segment morphogenesis are still largely unknown. Unlike typical cilia, the outer segment is continuously regenerated or renewed throughout the life of the animal through the combined process of distal outer segment shedding and proximal outer segment growth. The process of outer segment renewal was discovered over forty years ago, but we still lack an understanding of how photoreceptors renew their outer segments and few, if any, molecular mechanisms that regulate outer segment growth or shedding have been described. Our lack of progress in understanding how photoreceptors renew their outer segments has been hampered by the difficulty in measuring rates of renewal. We have created a new method that uses heat-shock induction of a fluorescent protein that can be used to rapidly measure outer segment growth rates. We describe this method, the stable transgenic line we created, and the growth rates observed in larval and adult rod photoreceptors using this new method. This new method will allow us to begin to define the genetic and molecular mechanisms that regulate rod outer segment renewal, a crucial aspect of photoreceptor function and, possibly, viability.

  15. STEREOLOGY AND SOME STRUCTURAL CORRELATES OF RETINAL AND PHOTORECEPTOR CELL FUNCTION

    Directory of Open Access Journals (Sweden)

    Terry M Mayhew

    2011-05-01

    Full Text Available The retina is the part of the eye which detects light, transduces it into nerve impulses and plays a significant role in visual perception. Sensitivity to light is multi-factorial and depends on the properties of photopigment molecules, their synthesis and incorporation into photoreceptor membranes and the neural circuitry between photoreceptor cells, bipolar neurons and ganglion neurons. In addition, it depends on structural factors such as the absolute and relative numbers of different types of photoreceptor neurons, their subcellular morphology, their distribution across the retina and the physical dimensions (especially surface areas and spatial arrangements of their photoreceptor membranes. At the molecular level, these membranes harbour photosensitive pigment molecules comprising transmembrane glycoproteins (opsins, which vary between photoreceptor cells and a non-protein chromophore. Phototransduction involves a conformational change in the chromophore and activation of an opsin. A transducer G protein, transducin, lowers levels of cGMP and triggers changes in membrane ion permeability including the closure of Na+ channels. This causes the plasmalemma to become less depolarized and the relative hyperpolarization stimulates ganglion cells whose axons form the optic nerve. Phosducin is a light-regulated phosphoprotein located in inner and outer segments of rod photoreceptor cells. It modulates phototransduction by binding to beta and gamma subunits of transducin. This review briefly illustrates ways in which stereology can contribute to our understanding of these processes by providing quantitative data on photoreceptor number, disk membrane surface area and the subcellular immunolocalisation of key molecules.

  16. The photochemical mechanism of a B12-dependent photoreceptor protein

    Science.gov (United States)

    Kutta, Roger J.; Hardman, Samantha J. O.; Johannissen, Linus O.; Bellina, Bruno; Messiha, Hanan L.; Ortiz-Guerrero, Juan Manuel; Elías-Arnanz, Montserrat; Padmanabhan, S.; Barran, Perdita; Scrutton, Nigel S.; Jones, Alex R.

    2015-08-01

    The coenzyme B12-dependent photoreceptor protein, CarH, is a bacterial transcriptional regulator that controls the biosynthesis of carotenoids in response to light. On binding of coenzyme B12 the monomeric apoprotein forms tetramers in the dark, which bind operator DNA thus blocking transcription. Under illumination the CarH tetramer dissociates, weakening its affinity for DNA and allowing transcription. The mechanism by which this occurs is unknown. Here we describe the photochemistry in CarH that ultimately triggers tetramer dissociation; it proceeds via a cob(III)alamin intermediate, which then forms a stable adduct with the protein. This pathway is without precedent and our data suggest it is independent of the radical chemistry common to both coenzyme B12 enzymology and its known photochemistry. It provides a mechanistic foundation for the emerging field of B12 photobiology and will serve to inform the development of a new class of optogenetic tool for the control of gene expression.

  17. Photoreceptors and neural circuitry underlying phototaxis in insects.

    Science.gov (United States)

    Yamaguchi, Satoko; Heisenberg, Martin

    2011-01-01

    Visual behavior of insects has long been studied, but it is only recently that a wide variety of genetic tools has become available for its analysis. Perhaps the most basic visual behaviour is phototaxis, locomotion towards a source of light. It is known in many insects and has been studied for over a century but the neural network underlying it is little understood. We recently described in the fruit fly Drosophila how different photoreceptor types contribute to phototaxis. By blocking subsets of them we showed that at least four of the five types are involved. In this short review, we compare phototactic behaviour in fruit flies and other insects (especially honeybees), and discuss what is known about the underlying neural circuitry. :

  18. Bifurcation analysis of a photoreceptor interaction model for Retinitis Pigmentosa

    Science.gov (United States)

    Camacho, Erika T.; Radulescu, Anca; Wirkus, Stephen

    2016-09-01

    Retinitis Pigmentosa (RP) is the term used to describe a diverse set of degenerative eye diseases affecting the photoreceptors (rods and cones) in the retina. This work builds on an existing mathematical model of RP that focused on the interaction of the rods and cones. We non-dimensionalize the model and examine the stability of the equilibria. We then numerically investigate other stable modes that are present in the system for various parameter values and relate these modes to the original problem. Our results show that stable modes exist for a wider range of parameter values than the stability of the equilibrium solutions alone, suggesting that additional approaches to preventing cone death may exist.

  19. Stimulus-evoked outer segment changes in rod photoreceptors

    Science.gov (United States)

    Zhao, Xiaohui; Thapa, Damber; Wang, Benquan; Lu, Yiming; Gai, Shaoyan; Yao, Xincheng

    2016-06-01

    Rod-dominated transient retinal phototropism (TRP) has been recently observed in freshly isolated mouse and frog retinas. Comparative confocal microscopy and optical coherence tomography revealed that the TRP was predominantly elicited from the rod outer segment (OS). However, the biophysical mechanism of rod OS dynamics is still unknown. Mouse and frog retinal slices, which displayed a cross-section of retinal photoreceptors and other functional layers, were used to test the effect of light stimulation on rod OSs. Time-lapse microscopy revealed stimulus-evoked conformational changes of rod OSs. In the center of the stimulated region, the length of the rod OS shrunk, while in the peripheral region, the rod OS swung toward the center region. Our experimental observation and theoretical analysis suggest that the TRP may reflect unbalanced rod disc-shape changes due to localized visible light stimulation.

  20. Long-term preservation of cone photoreceptors and visual acuity in rd10 mutant mice exposed to continuous environmental enrichment.

    Science.gov (United States)

    Barone, Ilaria; Novelli, Elena; Strettoi, Enrica

    2014-01-01

    In human patients and animal models of retinitis pigmentosa (RP), a gradual loss of rod photoreceptors and decline in scotopic vision are the primary manifestations of the disease. Secondary death of cones and gradual, regressive remodeling of the inner retina follow and progress at different speeds according to the underlying genetic defect. In any case, the final outcome is near-blindness without a conclusive cure yet. We recently reported that environmental enrichment (EE), an experimental manipulation based on exposure to enhanced motor, sensory, and social stimulation, when started at birth, exerts clear beneficial effects on a mouse model of RP, by slowing vision loss. The purpose of this study was to investigate in the same mouse the long-term effects of chronic exposure to an EE and assess the outcome of this manipulation on cone survival, inner retinal preservation, and visual behavior. Two groups of rd10 mutant mice were maintained in an EE or standard (ST) laboratory conditions up to 1 year of age. Then, retinal preservation was assessed with immunocytochemistry, confocal microscopy examination, cone counts, and electron microscopy of the photoreceptor layer, while visual acuity was tested behaviorally with a Prusky water maze. rd10 mice are a model of autosomal recessive RP with a typical rod-cone, center to the periphery pattern of photoreceptor degeneration. They carry a mutation of the rod-specific phosphodiesterase gene and undergo rod death that peaks at around P24, while cone electroretinogram (ERG) is extinct by P60. We previously showed that early exposure to an EE efficiently delays photoreceptor degeneration in these mutants, extending the time window of cone viability and cone-mediated vision well beyond the phase of maximum rod death. Here we find that a maintained EE can delay the degeneration of cones even in the long term. Confocal and electron microscopy examination of the retinas of the rd10 EE and ST mice at 1 year of age showed major

  1. Mechanisms underlying stage-1 TRPL channel translocation in Drosophila photoreceptors.

    Directory of Open Access Journals (Sweden)

    Minh-Ha Lieu

    Full Text Available BACKGROUND: TRP channels function as key mediators of sensory transduction and other cellular signaling pathways. In Drosophila, TRP and TRPL are the light-activated channels in photoreceptors. While TRP is statically localized in the signaling compartment of the cell (the rhabdomere, TRPL localization is regulated by light. TRPL channels translocate out of the rhabdomere in two distinct stages, returning to the rhabdomere with dark-incubation. Translocation of TRPL channels regulates their availability, and thereby the gain of the signal. Little, however, is known about the mechanisms underlying this trafficking of TRPL channels. METHODOLOGY/PRINCIPAL FINDINGS: We first examine the involvement of de novo protein synthesis in TRPL translocation. We feed flies cycloheximide, verify inhibition of protein synthesis, and test for TRPL translocation in photoreceptors. We find that protein synthesis is not involved in either stage of TRPL translocation out of the rhabdomere, but that re-localization to the rhabdomere from stage-1, but not stage-2, depends on protein synthesis. We also characterize an ex vivo eye preparation that is amenable to biochemical and genetic manipulation. We use this preparation to examine mechanisms of stage-1 TRPL translocation. We find that stage-1 translocation is: induced with ATP depletion, unaltered with perturbation of the actin cytoskeleton or inhibition of endocytosis, and slowed with increased membrane sterol content. CONCLUSIONS/SIGNIFICANCE: Our results indicate that translocation of TRPL out of the rhabdomere is likely due to protein transport, and not degradation/re-synthesis. Re-localization from each stage to the rhabdomere likely involves different strategies. Since TRPL channels can translocate to stage-1 in the absence of ATP, with no major requirement of the cytoskeleton, we suggest that stage-1 translocation involves simple diffusion through the apical membrane, which may be regulated by release of a

  2. The Leber congenital amaurosis protein AIPL1 and EB proteins co-localize at the pho