Rapid accumulation of glutathione during light stress in Arabidopsis.

PubMed

Choudhury, Feroza K; Devireddy, Amith R; Azad, Rajeev K; Shulaev, Vladimir; Mittler, Ron

2018-05-25

Environmental stress conditions can drastically affect plant growth and productivity. In contrast to soil moisture or salinity that can gradually change over a period of days or weeks, changes in light intensity or temperature can occur very rapidly, sometimes over the course of minutes or seconds. We previously reported that in response to rapid changes in light intensity (0-60 sec), Arabidopsis thaliana plants mount a large-scale transcriptomic response that includes several different transcripts essential for light stress acclimation. Here, we expand our analysis of the rapid response of Arabidopsis to light stress using a metabolomics approach and identify 111 metabolites that significantly alter in their level during the first 90 sec of light stress exposure. We further show that the levels of free and total glutathione accumulate rapidly during light stress in Arabidopsis and that the accumulation of total glutathione during light stress is associated with an increase in nitric oxide (NO) levels. We further suggest that the increase in precursors for glutathione biosynthesis could be linked to alterations in photorespiration, and that phosphoenolpyruvate could represent a major energy and carbon source for rapid metabolic responses. Taken together, our analysis could be used as an initial road map for the identification of different pathways that could be used to augment the rapid response of plants to abiotic stress. In addition, it highlights the important role of glutathione in these responses.

Light environment change induces differential expression of guppy opsins in a multi-generational evolution experiment.

PubMed

Kranz, Alexandrea M; Forgan, Leonard G; Cole, Gemma L; Endler, John A

2018-06-19

Light environments critically impact species that rely on vision to survive and reproduce. Animal visual systems must accommodate changes in light that occur from minutes to years, yet the mechanistic basis of their response to spectral (color) changes is largely unknown. Here we used a laboratory experiment where replicate guppy populations were kept under three different light environments for up to 8-12 generations to explore possible differences in the expression levels of nine guppy opsin genes. Previous evidence for opsin expression-light environment 'tuning' has been either correlative or focused exclusively on the relationship between the light environment and opsin expression over one or two generations. In our multi-generation experiment, the relative expression levels of nine different guppy opsin genes responded differently to light environment changes: some did not respond, while others differed due to phenotypic plasticity. Moreover, for the LWS-1 opsin we found that, while we observed a wide range of plastic responses under different light conditions, common plastic responses (where the population replicates all followed the same trajectory) occurred only after multigenerational exposure to different light environments. Taken together this suggests that opsin expression plasticity plays an important role in light environment 'tuning' in different light environments on different time scales, and, in turn, has important implications for both visual system function and evolution. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Solar UV light regulates flavonoid metabolism in apple (Malus x domestica).

PubMed

Henry-Kirk, Rebecca A; Plunkett, Blue; Hall, Miriam; McGhie, Tony; Allan, Andrew C; Wargent, Jason J; Espley, Richard V

2018-03-01

Ultraviolet-B light (UV-B) is one environmental signal perceived by plants that affects the flavonoid pathway and influences the levels of anthocyanins, flavonols, and proanthocyanidins. To understand the mechanisms underlying UV exposure, apple trees were grown under spectral filters that altered transmission of solar UV light. Fruit analysis showed that UV induced changes in physiology, metabolism, and gene expression levels during development over a season. These changes were sustained after storage. Under low UV, ripening was delayed, fruit size decreased, and anthocyanin and flavonols were reduced. Expression analysis showed changes in response to UV light levels for genes in the regulation and biosynthesis of anthocyanin and flavonols. Transcription of flavonol synthase (FLS), ELONGATED HYPOCOTYL 5 (HY5), MYB10, and MYB22 were down-regulated throughout fruit development under reduced UV. Functional testing showed that the FLS promoter was activated by HY5, and this response was enhanced by the presence of MYB22. The MYB22 promoter can also be activated by the anthocyanin regulator, MYB10. As ambient levels of UV light vary around the globe, this study has implications for future crop production, the quality of which can be determined by the response to UV. © 2018 John Wiley & Sons Ltd.

Early changes in staurosporine-induced differentiated RGC-5 cells indicate cellular injury response to nonlethal blue light exposure.

PubMed

Zhang, Pei; Huang, Chen; Wang, Wei; Wang, Minshu

2015-06-01

Blue light has been previously demonstrated to induce injury of retinal cells. The cellular responses to nonlethal blue light exposure for each type of retinal cell are of particular interest but remain undetermined. Based on the doses of blue light reported in previous research to be nonlethal to retinal pigment epithelial cells, here we investigated whether and to what extent such doses of blue light are cytotoxic to staurosporine-differentiated RGC-5 cells. RGC-5 cells were differentiated for 24 hours using 200 nM staurosporine. The resulting cells were cultured and exposed to blue light at three different energy levels (1, 10, and 50 J cm(-2)). Cellular morphologies were investigated with an inverted microscope and cell viability was assessed with a Cell Counting Kit-8 (CCK-8) assay. The generation of intracellular reactive oxygen species (ROS) was evaluated by H2DCFDA. After loading of MitoTracker Green FM dye, the mitochondrial contents were analyzed using flow cytometry. The lactate dehydrogenase (LDH) activities in the media were also measured. The level of lipid peroxidation was determined by measuring the amount of malondialdehyde (MDA). Treatment of the cells for 24 hours with 200 nM staurosporine successfully induced the differentiation of RGC-5 cells. No morphological changes were observed in the ssdRGC-5 cells exposed to blue light at 50 J cm(-2), which was the highest energy level tested. Exposure of the ssdRGC-5 cells to this energy level of blue light did, however, decrease their numbers by approximately 72.1% compared to the numbers of such cells found after being left in the dark. Remarkably, the levels of ROS generation and mitochondrial contents were, respectively, increased to 142% and 118% of those of the control by a 10 J cm(-2) exposure of blue light. The LDH activities and MDA levels exhibited no obvious changes in the blue light-exposed ssdRGC-5 cells compared to the control cells. In vitro nonlethal blue light exposure led to cellular damage of staurosporine-differentiated RGC-5 cells. These increases in oxidative stress and mitochondrial content were the early steps of the cellular response to the exposure of relatively low doses (10 J cm(-2)) of blue light.

Dim light at night disrupts molecular circadian rhythms and increases body weight.

PubMed

Fonken, Laura K; Aubrecht, Taryn G; Meléndez-Fernández, O Hecmarie; Weil, Zachary M; Nelson, Randy J

2013-08-01

With the exception of high latitudes, life has evolved under bright days and dark nights. Most organisms have developed endogenously driven circadian rhythms that are synchronized to this daily light/dark cycle. In recent years, humans have shifted away from the naturally occurring solar light cycle in favor of artificial and sometimes irregular light schedules produced by electric lighting. Exposure to unnatural light cycles is increasingly associated with obesity and metabolic syndrome; however, the means by which environmental lighting alters metabolism are poorly understood. Thus, we exposed mice to dim light at night and investigated changes in the circadian system and metabolism. Here we report that exposure to ecologically relevant levels of dim (5 lux) light at night altered core circadian clock rhythms in the hypothalamus at both the gene and protein level. Circadian rhythms in clock expression persisted during light at night; however, the amplitude of Per1 and Per2 rhythms was attenuated in the hypothalamus. Circadian oscillations were also altered in peripheral tissues critical for metabolic regulation. Exposure to dimly illuminated, as compared to dark, nights decreased the rhythmic expression in all but one of the core circadian clock genes assessed in the liver. Additionally, mice exposed to dim light at night attenuated Rev-Erb expression in the liver and adipose tissue. Changes in the circadian clock were associated with temporal alterations in feeding behavior and increased weight gain. These results are significant because they provide evidence that mild changes in environmental lighting can alter circadian and metabolic function. Detailed analysis of temporal changes induced by nighttime light exposure may provide insight into the onset and progression of obesity and metabolic syndrome, as well as other disorders involving sleep and circadian rhythm disruption.

Melanopsin changes in neonatal albino rat independent of rods and cones.

PubMed

Hannibal, Jens; Georg, Birgitte; Fahrenkrug, Jan

2007-01-08

Intrinsically photosensitive retinal ganglion cells employ the photopigment melanopsin and provide light information to brain areas responsible for the regulation of circadian rhythms. The expression of melanopsin is regulated by environmental illumination, but it remains to be clarified whether the rods and cones are involved. Here, we examined the influence of 5 days of constant light and dark conditions on melanopsin mRNA and protein expression in newborn albino rats, in which functional rods and cones have not yet been developed. We found that the melanopsin mRNA level was unaffected, whereas the melanopsin protein level was more than two-fold higher in the darkness-adapted group than in pups raised in constant light. In pups raised during 12 : 12 h light/dark cycles, the melanopsin protein level was significantly higher during the day than at night. Our findings indicate that melanopsin protein changes are independent of input from the rods and cones.

Effects of turbidity, light level, and cover on predation of white sturgeon larvae by prickly sculpins

USGS Publications Warehouse

Gadomski, D.M.; Parsley, M.J.

2005-01-01

White sturgeon Acipenser transmontanus occur in rivers of the western United States and southwestern Canada, but some populations are in decline because of recruitment failure. Many river systems in this area have been altered as a result of development that has caused major environmental changes. Our goal was to examine how three changes - lower turbidity levels, higher light levels, and altered substrates - might affect predation by prickly sculpin Cottus asper on white sturgeon larvae. We experimentally investigated predation at various turbidity levels and found that significantly more white sturgeon yolk sac larvae were eaten at lower turbidity levels. The effects of light level (1-4 and 7-15 1x), the presence or absence of rocks as cover, and prey size (14-17 mm and 20-24 mm total length) on the outcome of predator-prey interactions were also examined. Significantly fewer white sturgeon were eaten during trials that combined the lowest light level, cover, and the smallest larvae. Our results suggest that altered river conditions caused by impoundment and other factors have increased predation on white sturgeon larvae. ?? Copyright by the American Fisheries Society 2005.

Light-regulated protein and mRNA synthesis in root caps of maize

NASA Technical Reports Server (NTRS)

Feldman, L. J.; Piechulla, B.; Sun, P. S.

1988-01-01

Illumination of maize roots initiates changes in mRNA levels and in the activities of proteins within the root cap. Using Northern analysis we showed a 5-6 fold increase in the levels of three specific mRNAs and a 14-fold increase in plastid mRNA. This increase is rapid, occurring within 30 minutes of illumination. With prolonged periods of darkness following illumination, messages return to levels observed in dark, control caps. For two species of mRNA illumination results in a reduction in message levels. Light-stimulated increases in the levels of specific mRNAs are proportionally greater than are increases in the activities of corresponding proteins. We suggest that the light-stimulated increase in protein activity in root caps may be preceded by and occur as a consequence of enhanced levels of mRNA. Our work suggests that photomorphogenesis in roots could involve changes in the levels of a wide variety of mRNAs within the root cap.

Examination of the interaction of different lighting conditions and chronic mild stress in animal model.

PubMed

Muller, A; Gal, N; Betlehem, J; Fuller, N; Acs, P; Kovacs, G L; Fusz, K; Jozsa, R; Olah, A

2015-09-01

We examined the effects of different shift work schedules and chronic mild stress (CMS) on mood using animal model. The most common international shift work schedules in nursing were applied by three groups of Wistar-rats and a control group with normal light-dark cycle. One subgroup from each group was subjected to CMS. Levels of anxiety and emotional life were evaluated in light-dark box. Differences between the groups according to independent and dependent variables were examined with one- and two-way analysis of variance, with a significance level defined at p < 0.05. Interaction of lighting regimen and CMS was proved to be significant according to time spent in the light compartment and the average number of changes between the light and dark compartments. Results of our examination confirm that the changes of lighting conditions evocate anxiety more prominently than CMS. No significant differences were found between the results of the low rotating group and the control group, supposing that this schedule is the least harmful to health. Our results on the association between the use of lighting regimens and the level of CMS provide evidence that the fast rotating shift work schedule puts the heaviest load on the organism of animals.

Light adaptation alters inner retinal inhibition to shape OFF retinal pathway signaling

PubMed Central

Mazade, Reece E.

2016-01-01

The retina adjusts its signaling gain over a wide range of light levels. A functional result of this is increased visual acuity at brighter luminance levels (light adaptation) due to shifts in the excitatory center-inhibitory surround receptive field parameters of ganglion cells that increases their sensitivity to smaller light stimuli. Recent work supports the idea that changes in ganglion cell spatial sensitivity with background luminance are due in part to inner retinal mechanisms, possibly including modulation of inhibition onto bipolar cells. To determine how the receptive fields of OFF cone bipolar cells may contribute to changes in ganglion cell resolution, the spatial extent and magnitude of inhibitory and excitatory inputs were measured from OFF bipolar cells under dark- and light-adapted conditions. There was no change in the OFF bipolar cell excitatory input with light adaptation; however, the spatial distributions of inhibitory inputs, including both glycinergic and GABAergic sources, became significantly narrower, smaller, and more transient. The magnitude and size of the OFF bipolar cell center-surround receptive fields as well as light-adapted changes in resting membrane potential were incorporated into a spatial model of OFF bipolar cell output to the downstream ganglion cells, which predicted an increase in signal output strength with light adaptation. We show a prominent role for inner retinal spatial signals in modulating the modeled strength of bipolar cell output to potentially play a role in ganglion cell visual sensitivity and acuity. PMID:26912599

Argon laser irradiation of rabbits' eyes-changes in prostaglandin E2 levels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Naveh, N.; Peer, J.; Bartov, E.

1991-02-01

Laser irradiation of the eye is a widely used therapeutic measure in various ocular disorders. We investigated in laser-treated rabbits' eyes the changes in prostaglandin E2 (PGE2) levels of the tissue affected by the laser (the retina/choroid) and of its adjacent vitreous over a two-week period. The parameters studied were; PGE2 in vitro production by the retina/choroid, as well as PGE2 and protein levels in the vitreous, the latter indicative of a break in the blood retinal barrier (BRB). The effect of noncoherent light exposure used for illumination, and that of the mechanical manipulation involved (sham exposure) were also studied.more » Following laser exposure vitreal PGE2 levels were increased two-fold above baseline (days three and 14), whereas light exposure resulted in a single peak. PGE2 in vitro production by the retina/choroid in the laser-exposed group was elevated throughout the observation period, peaking twice (days 3 and 14), in the light-exposed group the enhanced production was evident during a shorter period, whereas in the sham group it remained unchanged from baseline. An elevation in vitreal protein levels to above baseline levels occurred in both the laser- and, to a lesser degree, in the noncoherent light-exposed groups, but not in the sham group. Our study demonstrated an enhanced PGE2 in vitro production by retina/choroid of laser-exposed eyes, which might be attributable to the additive effect of the laser induced trauma, and the noncoherent light photochemical changes; the clinical significance of the recurrent increase in vitreal PGE2 levels in laser-treated eyes might be related to its anti-inflammatory properties.« less

The impacts of new street light technologies: experimentally testing the effects on bats of changing from low-pressure sodium to white metal halide

PubMed Central

Stone, Emma Louise; Wakefield, Andrew; Harris, Stephen; Jones, Gareth

2015-01-01

Artificial light at night is a major feature of anthropogenic global change and is increasingly recognized as affecting biodiversity, often negatively. On a global scale, newer technology white lights are replacing orange sodium lights to reduce energy waste. In 2009, Cornwall County Council (UK) commenced replacement of existing low-pressure sodium (LPS) high intensity discharge (HID) street lights with new Phillips CosmoPolis white ceramic metal halide street lights to reduce energy wastage. This changeover provided a unique collaborative opportunity to implement a before-after-control-impact field experiment to investigate the ecological effects of newly installed broad spectrum light technologies. Activity of the bat species Pipistrellus pipistrellus, P. pygmaeus and Nyctalus/Eptesicus spp. was significantly higher at metal halide than LPS lights, as found in other studies of bat activity at old technology (i.e. mercury vapour) white light types. No significant difference was found in feeding attempts per bat pass between light types, though more passes overall were recorded at metal halide lights. Species-specific attraction of bats to the metal halide lights could have cascading effects at lower trophic levels. We highlight the need for further research on possible ecosystem-level effects of light technologies before they are installed on a wide scale. PMID:25780239

Dim artificial light at night affects mating, reproductive output, and reactive oxygen species in Drosophila melanogaster.

PubMed

McLay, Lucy Katherine; Nagarajan-Radha, Venkatesh; Green, Mark Philip; Jones, Therésa Melanie

2018-05-07

Humans are lighting the night-time environment with ever increasing extent and intensity, resulting in a variety of negative ecological effects in individuals and populations. Effects of light at night on reproductive fitness traits are demonstrated across taxa however, the mechanisms underlying these effects are largely untested. One possible mechanism is that light at night may result in perturbed reactive oxygen species (ROS) and oxidative stress levels. Here, we reared Drosophila melanogaster under either dim (10 lx) light or no light (0 lx) at night for three generations and then compared mating and lifetime oviposition patterns. In a second experiment, we explored whether exposure to light at night treatments resulted in variation in ROS levels in the heads and ovaries of six, 23- and 36-day-old females. We demonstrate that dim light at night affects mating and reproductive output: 10 lx flies courted for longer prior to mating, and female oviposition patterns differed to 0 lx females. ROS levels were lower in the ovaries but not heads, of 10 lx compared with 0 lx females. We suggest that reduced ROS levels may reflect changes in ovarian physiology and cell signaling, which may be related to the differences observed in oviposition patterns. Taken together, our results indicate negative consequences for invertebrates under more stressful, urban, lit conditions and further investigation into the mechanisms driving these changes is warranted to manage invertebrate communities in a brighter future. © 2018 Wiley Periodicals, Inc.

Electrically controlled crossing of energy levels in quantum dots in two-dimensional topological insulators

NASA Astrophysics Data System (ADS)

Sukhanov, Aleksei A.

2017-05-01

We study the energy spectra of bound states in quantum dots (QDs) formed by an electrostatic potential in two-dimensional topological insulator (TI) and their transformation with changes in QD depth and radius. It is found that, unlike a trivial insulator, the energy difference between the levels of the ground state and first excited state can decrease with decreasing the radius and increasing the depth of the QD so that these levels intersect under some critical condition. The crossing of the levels results in unusual features of optical properties caused by intraceneter electron transitions. In particular, it leads to significant changes of light absorption due to electron transitions between such levels and to the transient electroluminescence induced by electrical tuning of QD and TI parameters. In the case of magnetic TIs, the polarization direction of the absorbed or emitted circularly polarized light is changed due to the level crossing.

Mixotrophy in Heterocapsa rotundata: A Mechanism for Dominating the Winter Phytoplankton Community

NASA Astrophysics Data System (ADS)

Millette, N.; Pierson, J. J.; Aceves, A.; Stoecker, D.

2016-02-01

Heterocapsa rotundata is a dinoflagellate that forms large winter blooms in estuaries and coastal ecosystems. Past research has focused on the mechanisms necessary for these winter blooms to form but it is unknown why H. rotundata consistently forms these blooms. H. rotundata is a known mixotroph, and we conducted grazing experiments with a non-axenic culture of H. rotundata containing bacteria to test what environmental conditions increase H. rotundata's community grazing rate. We used microspheres to confirm that H. rotundata was grazing. We measured the change of bacterial abundance in control (without grazers) and experimental groups over 24 hours to estimate H. rotundata's community grazing rate on bacteria at different irradiance levels and ammonium concentrations. There was a significant interaction between the effect of ammonium concentration and irradiance levels. As irradiance levels decreased, the effect of ammonium concentrations on H. rotundata grazing rates became less pronounced. At lower irradiance levels H. rotundata grazing rates remained high, regardless of the ammonium concentration. Overall, changes in irradiance levels had a larger impact on H. rotundata grazing rates than changes in ammonium concentration. The findings will be discussed in light of ongoing lab and field research. The winter season is known for limiting light levels that most likely have a negative impact on phytoplankton growth rates. Heterocapsa rotundata has adapted to low light levels by increasing grazing on bacteria to consume enough carbon to maintain growth. Heterocapsa rotundata's response to low light levels is likely the mechanism that provides the competitive advantage to form winter blooms under the right conditions over other phytoplankton species.

Effects of Elevated CO2 on Levels of Primary Metabolites and Transcripts of Genes Encoding Respiratory Enzymes and Their Diurnal Patterns in Arabidopsis thaliana: Possible Relationships with Respiratory Rates

PubMed Central

Watanabe, Chihiro K.; Sato, Shigeru; Yanagisawa, Shuichi; Uesono, Yukifumi; Terashima, Ichiro; Noguchi, Ko

2014-01-01

Elevated CO2 affects plant growth and photosynthesis, which results in changes in plant respiration. However, the mechanisms underlying the responses of plant respiration to elevated CO2 are poorly understood. In this study, we measured diurnal changes in the transcript levels of genes encoding respiratory enzymes, the maximal activities of the enzymes and primary metabolite levels in shoots of Arabidopsis thaliana grown under moderate or elevated CO2 conditions (390 or 780 parts per million by volume CO2, respectively). We examined the relationships between these changes and respiratory rates. Under elevated CO2, the transcript levels of several genes encoding respiratory enzymes increased at the end of the light period, but these increases did not result in changes in the maximal activities of the corresponding enzymes. The levels of some primary metabolites such as starch and sugar phosphates increased under elevated CO2, particularly at the end of the light period. The O2 uptake rate at the end of the dark period was higher under elevated CO2 than under moderate CO2, but higher under moderate CO2 than under elevated CO2 at the end of the light period. These results indicate that the changes in O2 uptake rates are not directly related to changes in maximal enzyme activities and primary metabolite levels. Instead, elevated CO2 may affect anabolic processes that consume respiratory ATP, thereby affecting O2 uptake rates. PMID:24319073

Light interference as a possible stressor altering HSP70 and its gene expression levels in brain and hepatic tissues of golden spiny mice.

PubMed

Ashkenazi, Lilach; Haim, Abraham

2012-11-15

Light at night and light interference (LI) disrupt the natural light:dark cycle, causing alterations at physiological and molecular levels, partly by suppressing melatonin (MLT) secretion at night. Heat shock proteins (HSPs) can be activated in response to environmental changes. We assessed changes in gene expression and protein level of HSP70 in brain and hepatic tissues of golden spiny mice (Acomys russatus) acclimated to LI for two (SLI), seven (MLI) and 21 nights (LLI). The effect of MLT treatment on LI-mice was also assessed. HSP70 levels increased in brain and hepatic tissues after SLI, whereas after MLI and LLI, HSP70 decreased to control levels. Changes in HSP70 levels as a response to MLT occurred after SLI only in hepatic tissue. However, hsp70 expression following SLI increased in brain tissue, but not in hepatic tissue. MLT treatment and SLI caused a decrease in hsp70 levels in brain tissue and an increase in hsp70 in hepatic tissue. SLI acclimation elicited a stress response in A. russatus, as expressed by increased HSP70 levels and gene expression. Longer acclimation decreases protein and gene expression to their control levels. We conclude that for brain and hepatic tissues of A. russatus, LI is a short-term stressor. Our results also revealed that A. russatus can acclimate to LI, possibly because of its circadian system plasticity, which allows it to behave both as a nocturnal and as a diurnal rodent. To the best of our knowledge, this is the first study showing the effect of LI as a stressor at the cellular level, by activating HSP70.

Changes in morning salivary melatonin correlate with prefrontal responses during working memory performance.

PubMed

Killgore, William D S; Kent, Haley C; Knight, Sara A; Alkozei, Anna

2018-04-11

Humans demonstrate a circadian rhythm of melatonin production that closely tracks the daily light/dark cycle, with profound increases in circulating levels during the night-time and nearly nonexistent levels during daylight hours. Although melatonin is known to play a role in preparing the brain and body for sleep, its effects on cognition and brain function are not well understood. We hypothesized that declines in morning melatonin would be associated with increased functional activation within cortical regions involved in alertness, attention, and executive function. We measured the change in salivary melatonin from mid-morning to late-morning in 26 healthy young adults who were also exposed to a 30-min period of blue or amber light followed by functional MRI during a working memory task (N-back). Brain activation was regressed on the change in melatonin scores from the mid-morning to late-morning saliva samples and the role of light exposure was also assessed. Although overall melatonin levels did not change significantly over the morning at the group level, individual declines in salivary melatonin were associated with significant increases in activation within the left dorsomedial and right inferior lateral prefrontal cortex during the 2-back condition (P<0.05, cluster corrected). Medial prefrontal activation also correlated modestly with better vigilance performance during the 0-back (P<0.05), but not the 1-back or 2-back conditions. The light condition did not affect the outcomes. These findings suggest declining melatonin levels in the morning are associated with increased prefrontal cortex functioning and may play a role in the increased frontal activation that occurs following awakening.

Changes in pigment, spectral transmission and element content of pink chicken eggshells with different pigment intensity during incubation.

PubMed

Yu, Yue; Li, Zhanming; Pan, Jinming

2016-01-01

Objective. The objective of this study was to investigate changes in pigment, spectral transmission and element content of chicken eggshells with different intensities of pink pigment during the incubation period. We also investigated the effects of the region (small pole, equator and large pole) and pink pigment intensity of the chicken eggshell on the percent transmission of light passing through the chicken eggshells. Method. Eggs of comparable weight from a meat-type breeder (Meihuang) were used, and divided based on three levels of pink pigment (light, medium and dark) in the eggshells. During the incubation (0-21 d), the values of the eggshell pigment (ΔE, L (∗), a (∗), b (∗)) were measured. The percent transmission of light for different regions and intensities of eggshell pigmentation was measured by using the visible wavelength range of 380-780 nm. Result. Three measured indicators of eggshell color, ΔE, L (∗) and a (∗), did not change significantly during incubation. Compared with other regions and pigment intensities, eggshell at the small pole and with light pigmentation intensity showed the highest percent transmission of light. The transmission value varied significantly (P < 0.001) with incubation time. The element analysis of eggshells with different levels of pink pigment showed that the potassium content of the eggshells for all pigment levels decreased significantly during incubation. Conclusion. In summary, pigment intensity and the region of the eggshell influenced the percent transmission of light of eggshell. Differences in the spectral characteristics of different eggshells may influence the effects of photostimulation during the incubation of eggs. All of these results will be applicable for perfecting the design of light intensity for lighted incubation to improve productivity.

Changes in pigment, spectral transmission and element content of pink chicken eggshells with different pigment intensity during incubation

PubMed Central

Yu, Yue; Li, Zhanming

2016-01-01

Objective. The objective of this study was to investigate changes in pigment, spectral transmission and element content of chicken eggshells with different intensities of pink pigment during the incubation period. We also investigated the effects of the region (small pole, equator and large pole) and pink pigment intensity of the chicken eggshell on the percent transmission of light passing through the chicken eggshells. Method. Eggs of comparable weight from a meat-type breeder (Meihuang) were used, and divided based on three levels of pink pigment (light, medium and dark) in the eggshells. During the incubation (0–21 d), the values of the eggshell pigment (ΔE, L∗, a∗, b∗) were measured. The percent transmission of light for different regions and intensities of eggshell pigmentation was measured by using the visible wavelength range of 380–780 nm. Result. Three measured indicators of eggshell color, ΔE, L∗ and a∗, did not change significantly during incubation. Compared with other regions and pigment intensities, eggshell at the small pole and with light pigmentation intensity showed the highest percent transmission of light. The transmission value varied significantly (P < 0.001) with incubation time. The element analysis of eggshells with different levels of pink pigment showed that the potassium content of the eggshells for all pigment levels decreased significantly during incubation. Conclusion. In summary, pigment intensity and the region of the eggshell influenced the percent transmission of light of eggshell. Differences in the spectral characteristics of different eggshells may influence the effects of photostimulation during the incubation of eggs. All of these results will be applicable for perfecting the design of light intensity for lighted incubation to improve productivity. PMID:27019785

Light-Induced Alterations in Basil Ganglia Kynurenic Acid Levels

NASA Technical Reports Server (NTRS)

Sroufe, Angela E.; Whittaker, J. A.; Patrickson, J. W.; Orr, M. C.

1997-01-01

The metabolic synthesis, release and breakdown of several known CNS neurotransmitters have been shown to follow a circadian pattern entrained to the environmental light/dark cycle. The levels of excitatory amino acid (EAA) transmitters such as glutamate, have been shown to vary with environmental lighting conditions. Kynurenic Acid (KA), an endogenous tryptophan metabolite and glutamate receptor antagonist, has been reported to have neuroprotective effects against EAA-induced excitotoxic cell damage. Changes in KA's activity within the mammalian basal ganglia has been proposed as being contributory to neurotoxicity in Huntington's Disease. It is not known whether CNS KA levels follow a circadian pattern or exhibit light-induced fluctuations. However, because the symptoms of certain degenerative motor disorders seem to fluctuate with daily 24 hour rhythm, we initiated studies to determine if basal ganglia KA were influenced by the daily light/dark cycle and could influence motor function. Therefore in this study, HPLC-EC was utilized to determine if basal ganglia KA levels in tissue extracts from adult male Long-Evans rats (200-250g) entrained to 24 and 48 hours constant light and dark conditions, respectively. Samples were taken one hour before the onset of the subjective day and one hour prior to the onset of the subjective night in order to detect possible phase differences in KA levels and to allow for accumulation of factors expressed in association with the light or dark phase. Data analysis revealed that KA levels in the basal ganglia vary with environmental lighting conditions; being elevated generally during the dark. Circadian phase differences in KA levels were also evident during the subjective night and subjective day, respectively. Results from these studies are discussed with respect to potential cyclic changes in neuronal susceptibility to excitotoxic damage during the daily 24 hour cycle and its possible relevance to future therapeutic approaches in treating neurodegenerative disorders.

Photoacclimation supports environmental tolerance of a sponge to turbid low-light conditions

NASA Astrophysics Data System (ADS)

Biggerstaff, A.; Smith, D. J.; Jompa, J.; Bell, J. J.

2015-12-01

Changes to coral reefs are occurring worldwide, often resulting in declining environmental quality which can be in the form of higher sedimentation rates and increased turbidity. While environmental acclimation to turbid and low-light conditions has been extensively studied in corals, far less is known about other phototrophic reef invertebrates. The photosynthetic cyanobacteria containing sponge Lamellodysidea herbacea is one of the most abundant sponges in the Wakatobi Marine National Park (WMNP, Indonesia), and its abundance is greatest at highly disturbed, turbid sites. This study investigated photoacclimation of L. herbacea symbionts to turbid reef sites using in situ PAM fluorometry combined with shading and transplant experiments at environmental extremes of light availability for this species. We found in situ photoacclimation of L. herbacea to both shallow, clear, high-light environments and deep, turbid, low-light environments. Shading experiments provide some evidence that L. herbacea are dependent on nutrition from their photosymbionts as significant tissue loss was seen in shaded sponges. Symbionts within surviving shaded tissue showed evidence of photoacclimation. Lamellodysidea herbacea transplanted from high- to low-light conditions appeared to have photoacclimated within 5 d with no significant effect of the lowered light level on survival. This ability of L. herbacea to photoacclimate to rapid and extreme changes in light availability may be one of the factors contributing to their survival on more turbid reef sites in the WMNP. Our study highlights the ability of some sponge species to acclimate to changes in light levels as a result of increased turbidity.

The impacts of new street light technologies: experimentally testing the effects on bats of changing from low-pressure sodium to white metal halide.

PubMed

Stone, Emma Louise; Wakefield, Andrew; Harris, Stephen; Jones, Gareth

2015-05-05

Artificial light at night is a major feature of anthropogenic global change and is increasingly recognized as affecting biodiversity, often negatively. On a global scale, newer technology white lights are replacing orange sodium lights to reduce energy waste. In 2009, Cornwall County Council (UK) commenced replacement of existing low-pressure sodium (LPS) high intensity discharge (HID) street lights with new Phillips CosmoPolis white ceramic metal halide street lights to reduce energy wastage. This changeover provided a unique collaborative opportunity to implement a before-after-control-impact field experiment to investigate the ecological effects of newly installed broad spectrum light technologies. Activity of the bat species Pipistrellus pipistrellus, P. pygmaeus and Nyctalus/Eptesicus spp. was significantly higher at metal halide than LPS lights, as found in other studies of bat activity at old technology (i.e. mercury vapour) white light types. No significant difference was found in feeding attempts per bat pass between light types, though more passes overall were recorded at metal halide lights. Species-specific attraction of bats to the metal halide lights could have cascading effects at lower trophic levels. We highlight the need for further research on possible ecosystem-level effects of light technologies before they are installed on a wide scale. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Impact of a single, short morning bright light exposure on tryptophan pathways and visuo- and sensorimotor performance: a crossover study.

PubMed

Schobersberger, Wolfgang; Blank, Cornelia; Hanser, Friedrich; Griesmacher, Andrea; Canazei, Markus; Leichtfried, Veronika

2018-04-23

Bright light (BL) has been shown to be effective in enhancing both cognitive and physical performances. Alterations in nighttime melatonin levels have also been observed. However, evaluations of light-induced changes in the preceding biochemical processes are absent. Therefore, the impact of a single morning BL exposure on sensorimotor and visuomotor performance, as well as tryptophan (trp) and trp metabolites, was evaluated in this study. In a crossover design, 33 healthy volunteers were randomly exposed to 30 min of < 150 lx at eye level (office light, OL) and 5000 lx at eye level (bright light, BL) of 6500 K in the morning hours. Trp, sulfatoxymelatonin (aMT6s), and kynurenine (kyn) courses over the morning hours were analyzed, and changes in sensori- and visuomotor measures were examined. Motoric performance increased in both setups, independent of light intensity. aMT6s and kyn decreased equally under both lighting conditions. Trp levels decreased from a mean (95% confidence interval) of 82.0 (77.2-86.9) to 66.5 (62.5-70.1) in the OL setup only. These data suggest that BL in the morning hours has a limited effect on visuo- and sensorimotor performance. Nevertheless, trp degradation pathways in the morning show diverse courses after OL and BL exposure. This suggests that trp courses can potentially be altered by BL exposure.

Once the Light Touch to the Brain: Cytotoxic Effects of Low-Dose Gamma-Ray, Laser Light, and Visible Light on Rat Neuronal Cell Culture

PubMed Central

Cakir, Murteza; Colak, Abdullah; Calikoglu, Cagatay; Taspinar, Numan; Sagsoz, Mustafa Erdem; Kadioglu, Hakan Hadi; Hacimuftuoglu, Ahmet; Seven, Sabriye

2016-01-01

Objective: We aimed to evaluate the effects of gamma-ray, laser light, and visible light, which neurons are commonly exposed to during treatment of various cranial diseases, on the viability of neurons. Materials and Methods: Neuronal cell culture was prepared from the frontal cortex of 9 newborn rats. Cultured cells were irradiated with gamma-ray for 1–10 min by 152Eu, 241Am, and 132Ba isotopes, visible light for 1–160 min, and laser light for 0.2–2 seconds. The MTT tetrazolium reduction assay was used to assess the number of viable cells in the neuronal cell cultures. Wavelength dispersive X-ray fluorescence spectrometer was used to determine Na, K, and Ca levels in cellular fluid obtained from neuronal cell culture plaques. Results: Under low-dose radiation with 152Eu, 241Am, and 132Ba isotopes, cell viability insignificantly decreased with time (p>0.05). On the other hand, exposure to visible light produced statistically significant decrease in cell viability at both short- (1–10 min) and long-term (20–160 min). Cell viability did not change with 2 seconds of laser exposure. Na, K, and Ca levels significantly decreased with gamma-ray and visible light. The level of oxidative stress markers significantly changed with gamma-ray. Conclusion: In conclusion, while low dose gamma-ray has slight to moderate apoptotic effect in neuronal cell cultures by oxidative stress, long-term visible light induces remarkable apoptosis and cell death. Laser light has no significant effect on neurons. Further genetic studies are needed to clarify the chronic effect of visible light on neuronal development and functions. PMID:27551168

The influence of changes in blood flow on the accuracy of pulse oximetry in humans.

PubMed

Vegfors, M; Lindberg, L G; Lennmarken, C

1992-05-01

Oxygen saturation (SpO2) was measured with a pulse oximeter in ten healthy, young men breathing air. A pulse oximeter probe was attached to the second toe and a laser Doppler probe to the first toe of the same foot for measurement of changes in peripheral blood flow. The pulse oximeter and laser Doppler readings were simultaneously compared when the foot was positioned 40 cm (position 1) above heart level, elevated 10 cm (position 2) above heart level and horizontally at heart level (position 3). Using this experimental human model, we achieved various blood flows. The AC and DC optical signals used for determination of oxygen saturation were recorded from the pulse oximeter and analysed. There was a significant increase (P less than 0.05) between position 1 and 3 in blood flow as measured by the laser Doppler flow meter. The corresponding pulse oximeter readings of haemoglobin saturation also increased significantly (P less than 0.05) comparing these two leg positions. Analysing the AC- and DC optical signals, the AC value of infrared light increased considerably, while the AC value of the red light decreased slightly. The DC values of red and infrared light did not change significantly. In summary, when blood flow was decreased, the ratio of red to infrared transmitted light was changed, resulting in a low SpO2 reading.

Long-term dim light during nighttime changes activity patterns and space use in experimental small mammal populations.

PubMed

Hoffmann, Julia; Palme, Rupert; Eccard, Jana Anja

2018-07-01

Artificial light at night (ALAN) is spreading worldwide and thereby is increasingly interfering with natural dark-light cycles. Meanwhile, effects of very low intensities of light pollution on animals have rarely been investigated. We explored the effects of low intensity ALAN over seven months in eight experimental bank vole (Myodes glareolus) populations in large grassland enclosures over winter and early breeding season, using LED garden lamps. Initial populations consisted of eight individuals (32 animals per hectare) in enclosures with or without ALAN. We found that bank voles under ALAN experienced changes in daily activity patterns and space use behavior, measured by automated radiotelemetry. There were no differences in survival and body mass, measured with live trapping, and none in levels of fecal glucocorticoid metabolites. Voles in the ALAN treatment showed higher activity at night during half moon, and had larger day ranges during new moon. Thus, even low levels of light pollution as experienced in remote areas or by sky glow can lead to changes in animal behavior and could have consequences for species interactions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Developmental Expression of Violaxanthin De-Epoxidase in Leaves of Tobacco Growing under High and Low Light1

PubMed Central

Bugos, Robert C.; Chang, Sue-Hwei; Yamamoto, Harry Y.

1999-01-01

Violaxanthin de-epoxidase (VDE) is a lumen-localized enzyme that catalyzes the de-epoxidation of violaxanthin in the thylakoid membrane upon formation of a transthylakoid pH gradient. We investigated the developmental expression of VDE in leaves of mature tobacco (Nicotiana tabacum) plants grown under high-light conditions (in the field) and low-light conditions (in a growth chamber). The difference in light conditions was evident by the increased pool size (violaxanthin + antheraxanthin + zeaxanthin, VAZ) throughout leaf development in field-grown plants. VDE activity based on chlorophyll or leaf area was low in the youngest leaves, with the levels increasing with increasing leaf age in both high- and low-light-grown plants. However, in high-light-grown plants, the younger leaves in early leaf expansion showed a more rapid increase in VDE activity and maintained higher levels of VDE transcript in more leaves, indicating that high light may induce greater levels of VDE. VDE transcript levels decreased substantially in leaves of mid-leaf expansion, while the levels of enzyme continued to increase, suggesting that the VDE enzyme does not turn over rapidly. The level of VDE changed in an inverse, nonlinear relationship with respect to the VAZ pool, suggesting that enzyme levels could be indirectly regulated by the VAZ pool. PMID:10482676

Developmental expression of violaxanthin de-epoxidase in leaves of tobacco growing under high and low light.

PubMed

Bugos, R C; Chang, S H; Yamamoto, H Y

1999-09-01

Violaxanthin de-epoxidase (VDE) is a lumen-localized enzyme that catalyzes the de-epoxidation of violaxanthin in the thylakoid membrane upon formation of a transthylakoid pH gradient. We investigated the developmental expression of VDE in leaves of mature tobacco (Nicotiana tabacum) plants grown under high-light conditions (in the field) and low-light conditions (in a growth chamber). The difference in light conditions was evident by the increased pool size (violaxanthin + antheraxanthin + zeaxanthin, VAZ) throughout leaf development in field-grown plants. VDE activity based on chlorophyll or leaf area was low in the youngest leaves, with the levels increasing with increasing leaf age in both high- and low-light-grown plants. However, in high-light-grown plants, the younger leaves in early leaf expansion showed a more rapid increase in VDE activity and maintained higher levels of VDE transcript in more leaves, indicating that high light may induce greater levels of VDE. VDE transcript levels decreased substantially in leaves of mid-leaf expansion, while the levels of enzyme continued to increase, suggesting that the VDE enzyme does not turn over rapidly. The level of VDE changed in an inverse, nonlinear relationship with respect to the VAZ pool, suggesting that enzyme levels could be indirectly regulated by the VAZ pool.

Crops Models for Varying Environmental Conditions

NASA Technical Reports Server (NTRS)

Jones, Harry; Cavazzoni, James; Keas, Paul

2001-01-01

New variable environment Modified Energy Cascade (MEC) crop models were developed for all the Advanced Life Support (ALS) candidate crops and implemented in SIMULINK. The MEC models are based on the Volk, Bugbee, and Wheeler Energy Cascade (EC) model and are derived from more recent Top-Level Energy Cascade (TLEC) models. The MEC models simulate crop plant responses to day-to-day changes in photosynthetic photon flux, photoperiod, carbon dioxide level, temperature, and relative humidity. The original EC model allows changes in light energy but uses a less accurate linear approximation. The simulation outputs of the new MEC models for constant nominal environmental conditions are very similar to those of earlier EC models that use parameters produced by the TLEC models. There are a few differences. The new MEC models allow setting the time for seed emergence, have realistic exponential canopy growth, and have corrected harvest dates for potato and tomato. The new MEC models indicate that the maximum edible biomass per meter squared per day is produced at the maximum allowed carbon dioxide level, the nominal temperatures, and the maximum light input. Reducing the carbon dioxide level from the maximum to the minimum allowed in the model reduces crop production significantly. Increasing temperature decreases production more than it decreases the time to harvest, so productivity in edible biomass per meter squared per day is greater at nominal than maximum temperatures, The productivity in edible biomass per meter squared per day is greatest at the maximum light energy input allowed in the model, but the edible biomass produced per light energy input unit is lower than at nominal light levels. Reducing light levels increases light and power use efficiency. The MEC models suggest we can adjust the light energy day-to- day to accommodate power shortages or Lise excess power while monitoring and controlling edible biomass production.

Noise and light exposures for extremely low birth weight newborns during their stay in the neonatal intensive care unit.

PubMed

Lasky, Robert E; Williams, Amber L

2009-02-01

The objectives of this study were to characterize noise and light levels for extremely low birth weight newborns throughout their stay in the NICU, evaluate factors influencing noise and light levels, and determine whether exposures meet recommendations from the American Academy of Pediatrics. Sound and light were measured inside the beds of extremely low birth weight newborns (n = 22) from birth to discharge. Measurements were recorded for 20 consecutive hours weekly from birth until 36 weeks' postmenstrual age, biweekly until 40 weeks, and every 4 weeks thereafter. Clinical variables including bed type and method of respiratory support were recorded at each session. Age-related changes in respiratory support and bed type explained the weekly increase of 0.22 dB in sound level and 3.67 lux in light level. Old incubators were the noisiest bed types, and new incubators were the quietest. Light levels were significantly higher in open beds than in incubators. The variations in noise and light levels over time were greatest for open beds. Noise and light levels were much less affected by respiratory support in incubators compared with open beds. A typical extremely low birth weight neonate was exposed to noise levels averaging 56.44 dB(A) and light levels averaging 70.56 lux during their stay from 26 to 42 weeks' postmenstrual age in the NICU. Noise levels were rarely within American Academy of Pediatrics recommendations (5.51% of the time), whereas light levels almost always met recommendations (99.37% of the time). Bed type and respiratory support explained differences in noise and light levels that extremely low birth weight newborns experience during their hospital stay. Noise levels exceeded recommendations, although evidence supporting those recommendations is lacking. Well-designed intervention studies are needed to determine the effects of noise reduction on the development of extremely low birth weight newborns.

Interaction of Light and Ethylene on Stem Gravitropism

NASA Technical Reports Server (NTRS)

Harrison, Marcia A.

1996-01-01

The major objective of this study was to evaluate light-regulated ethylene production during gravitropic bending in etiolated pea stems. Previous investigations indicated that ethylene production increases after gravistimulation and is associated with the later (counter-reactive) phase of bending. Additionally, changes in the counter-reaction and locus of curvature during gravitropism are greatly influenced by red light and ethylene production. Ethylene production may be regulated by the levels of available precursor (1-aminocyclopropane-l-carboxylic acid, ACC) via its synthesis, conjugation to malonyl-ACC or glutamyl-ACC, or oxidation to ethylene. The regulation of ethylene production by quantifying ACC and conjugated ACC levels in gravistimulated pea stemswas examined. Also measured was the changes in protein and enzyme activity associated with gravitropic curvature by electrophoretic and spectrophotometric techniques. An image analysis system was used to visualize and quantify enzymatic activity and transcriptional products in gravistimulated and red-light treated etiolated pea stem tissues.

Visualizing Sound: Demonstrations to Teach Acoustic Concepts

NASA Astrophysics Data System (ADS)

Rennoll, Valerie

Interference, a phenomenon in which two sound waves superpose to form a resultant wave of greater or lower amplitude, is a key concept when learning about the physics of sound waves. Typical interference demonstrations involve students listening for changes in sound level as they move throughout a room. Here, new tools are developed to teach this concept that provide a visual component, allowing individuals to see changes in sound level on a light display. This is accomplished using a microcontroller that analyzes sound levels collected by a microphone and displays the sound level in real-time on an LED strip. The light display is placed on a sliding rail between two speakers to show the interference occurring between two sound waves. When a long-exposure photograph is taken of the light display being slid from one end of the rail to the other, a wave of the interference pattern can be captured. By providing a visual component, these tools will help students and the general public to better understand interference, a key concept in acoustics.

γ-glutamyl transpeptidase 1 specifically suppresses green-light avoidance via GABAA receptors in Drosophila.

PubMed

Liu, Jiangqu; Gong, Zhefeng; Liu, Li

2014-08-01

Drosophila larvae innately show light avoidance behavior. Compared with robust blue-light avoidance, larvae exhibit relatively weaker green-light responses. In our previous screening for genes involved in larval light avoidance, compared with control w(1118) larvae, larvae with γ-glutamyl transpeptidase 1 (Ggt-1) knockdown or Ggt-1 mutation were found to exhibit higher percentage of green-light avoidance which was mediated by Rhodopsin6 (Rh6) photoreceptors. However, their responses to blue light did not change significantly. By adjusting the expression level of Ggt-1 in different tissues, we found that Ggt-1 in malpighian tubules was both necessary and sufficient for green-light avoidance. Our results showed that glutamate levels were lower in Ggt-1 null mutants compared with controls. Feeding Ggt-1 null mutants glutamate can normalize green-light avoidance, indicating that high glutamate concentrations suppressed larval green-light avoidance. However, rather than directly, glutamate affected green-light avoidance indirectly through GABA, the level of which was also lower in Ggt-1 mutants compared with controls. Mutants in glutamate decarboxylase 1, which encodes GABA synthase, and knockdown lines of the GABAA receptor, both exhibit elevated levels of green-light avoidance. Thus, our results elucidate the neurobiological mechanisms mediating green-light avoidance, which was inhibited in wild-type larvae. © 2014 International Society for Neurochemistry.

Light-induced morphological alteration in anthocyanin-accumulating vacuoles of maize cells

PubMed Central

Irani, Niloufer G; Grotewold, Erich

2005-01-01

Background Plant pigmentation is affected by a variety of factors. Light, an important plant developmental signal, influences the accumulation of anthocyanins primarily through the activation of the transcription factors that regulate the flavonoid biosynthetic pathway. In this study, we utilized maize Black Mexican Sweet (BMS) cells expressing the R and C1 regulators of anthocyanin biosynthesis from a light-insensitive promoter as a means to investigate the existence of additional levels of control of pigmentation by light. Results BMS cells expressing the R and C1 regulators from the CaMV 35S constitutive promoter accumulate anthocyanins when grown in complete darkness, suggesting that the transcription factors R and C1 are sufficient for the transcription of the genes corresponding to the structural enzymes of the pathway, with no requirement for additional light-induced regulators. Interestingly, light induces a "darkening" in the color of the purple anthocyanin pigmentation of transgenic BMS cells expressing R and C1. This change in the pigment hue is not associated with a variation in the levels or types of anthocyanins present, or with an alteration of the transcript levels of several flavonoid biosynthetic genes. However, cytological observations show that light drives unexpected changes in the morphology and distribution of the anthocyanins-containing vacuolar compartments. Conclusion By uncoupling the effect of light on anthocyanin accumulation, we have found light to induce the fusion of anthocyanin-containing vacuoles, the coalescence of anthocyanic vacuolar inclusion (AVI)-like structures contained, and the spread of anthocyanins from the inclusions into the vacuolar sap. Similar light-induced alterations in vacuolar morphology are also evident in the epidermal cells of maize floral whorls accumulating anthocyanins. Our findings suggest a novel mechanism for the action of light on the vacuolar storage of anthocyanin. PMID:15907203

Light Pollution: Outdoor lighting is a growing threat to astronomy.

PubMed

Riegel, K W

1973-03-30

There have been major qualitative and quantitative changes in outdoor lighting technology in the last decade. The level of skylight caused by outdoor lighting systems is growing at a very high rate, about 20 percent per year nationwide. In addition, the spectral distribution of man-made light pollution may change in the next decade from one containing a few mercury lines to one containing dozens of lines and a significantly increased continuum level. Light pollution is presently damaging to some astronomical programs, and it is likely to become a major factor limiting progress in the next decade. Suitable sites in the United States for new dark sky observing facilities are very difficult to find. Some of the increase in outdoor illumination is due to the character of national growth and development. Some is due to promotional campaigns, in which questionable arguments involving public safety are presented. There are protective measures which might be adopted by the government; these would significantly aid observational astronomy, without compromising the legitimate outdoor lighting needs of society. Observatories should establish programs to routinely monitor sky brightness as a function of position, wavelength, and time. The astronomical community should establish a mechanism by which such programs can be supported and coordinated.

Ultrasonic signal enhancement by resonator techniques

NASA Technical Reports Server (NTRS)

Heyman, J. S.

1973-01-01

Ultrasonic resonators increase experimental sensitivity to acoustic dispersion and changes in attenuation. Experimental sensitivity enhancement line shapes are presented which were obtained by modulating the acoustic properties of a CdS resonator with a light beam. Small changes in light level are made to produce almost pure absorptive or dispersive changes in the resonator signal. This effect is due to the coupling of the ultrasonic wave to the CdS conductivity which is proportional to incident light intensity. The resonator conductivity is adjusted in this manner to obtain both dispersive and absorptive sensitivity enhancement line shapes. The data presented verify previous thoretical calculations based on a propagating wave model.

Very preterm infants can detect small variations in light levels in incubators.

PubMed

Zores, Claire; Dufour, André; Pebayle, Thierry; Langlet, Claire; Astruc, Dominique; Kuhn, Pierre

2015-10-01

This prospective observational study was designed to improve our understanding of the responses of very preterm infants to light level variations in incubators and to evaluate what determined those reactions. The physiological responses of 27 very preterm infants were analysed following variations in the light level environments of their incubators over 10 hours. Heart and respiratory rates, systemic oxygen saturation and regional cerebral oxygen saturations were recorded using near-infrared spectroscopy, and the variation of each parameter was analysed. We analysed 332 light level changes. Heart rate increased by 3.8 beats per minute (range -2.6 to 12.6), respiratory rate by six cycles per minute (-1.5 to 26) and regional cerebral oxygen saturation by 1.1% (-0.5% to 3.9%) (p < 0.05 each) when delta lux was over 50. Only respiratory rate decreased significantly, by -8.4 cycles per minute (-28 to -0.4), when delta lux was 50 or lower (p < 0.05). The initial level of illumination altered the very preterm infants' responses, with higher reactivity for higher ambient light levels. Very preterm infants reacted to moderate variations in illumination in their incubator, within recommended ranges of light levels, suggesting that they may detect even small light level variations. ©2015 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

Light-Irradiation Wavelength and Intensity Changes Influence Aflatoxin Synthesis in Fungi

PubMed Central

Suzuki, Tadahiro

2018-01-01

Fungi respond to light irradiation by forming conidia and occasionally synthesizing mycotoxins. Several light wavelengths, such as blue and red, affect the latter. However, the relationship between light irradiation and mycotoxin synthesis varies depending on the fungal species or strain. This study focused on aflatoxin (AF), which is a mycotoxin, and the types of light irradiation that increase AF synthesis. Light-irradiation tests using the visible region indicated that blue wavelengths in the lower 500 nm region promoted AF synthesis. In contrast, red wavelengths of 660 nm resulted in limited significant changes compared with dark conditions. Irradiation tests with different intensity levels indicated that a low light intensity increased AF synthesis. For one fungal strain, light irradiation decreased the AF synthesis under all wavelength conditions. However, the decrease was mitigated by 525 nm low intensity irradiation. Thus, blue-green low intensity irradiation may increase AF synthesis in fungi. PMID:29304012

Stressful colours: corticosterone concentrations in a free-living songbird vary with the spectral composition of experimental illumination

PubMed Central

Ouyang, Jenny Q.; de Jong, Maaike; Hau, Michaela; Visser, Marcel E.; van Grunsven, Roy H. A.; Spoelstra, Kamiel

2015-01-01

Organisms have evolved under natural daily light/dark cycles for millions of years. These cycles have been disturbed as night-time darkness is increasingly replaced by artificial illumination. Investigating the physiological consequences of free-living organisms in artificially lit environments is crucial to determine whether nocturnal lighting disrupts circadian rhythms, changes behaviour, reduces fitness and ultimately affects population numbers. We make use of a unique, large-scale network of replicated field sites which were experimentally illuminated at night using lampposts emanating either red, green, white or no light to test effect on stress hormone concentrations (corticosterone) in a songbird, the great tit (Parus major). Adults nesting in white-light transects had higher corticosterone concentrations than in the other treatments. We also found a significant interaction between distance to the closest lamppost and treatment type: individuals in red light had higher corticosterone levels when they nested closer to the lamppost than individuals nesting farther away, a decline not observed in the green or dark treatment. Individuals with high corticosterone levels had fewer fledglings, irrespective of treatment. These results show that artificial light can induce changes in individual hormonal phenotype. As these effects vary considerably with light spectrum, it opens the possibility to mitigate these effects by selecting street lighting of specific spectra. PMID:26311159

Effects of guidelines implementation in a surgical intensive care unit to control nighttime light and noise levels.

PubMed

Walder, B; Francioli, D; Meyer, J J; Lançon, M; Romand, J A

2000-07-01

Because of around-the-clock activities, environmental noise and light are among the many causes of sleep disturbance in an intensive care unit (ICU). The implementation of guidelines may potentially change behavior rules and improve sleep quality. A prospective interventional study, observing the effects of simple nighttime guidelines on light and noise levels in an ICU. A modern surgical ICU, subdivided into six identical three-bed rooms. Critically ill adult patients. Between two observation periods, five guidelines were implemented to decrease both light and noise during the night shift in the patient's room. Light levels and noise levels were obtained using a luxmeter and a sound level meter [A-weighted decibels (dB) scale] and were monitored continuously from 11 pm to 5 am both before (period P1) and after (period P2) the implementation of guidelines. Similar patient's gravity and nursing workload scores were observed between P1 and P2. A low mean (<5 Lux) and maximal light level were measured during both P1 and P2. The implementation of guidelines lowered mean light disturbance intensity with a greater variability of light during P2. All noise levels were high and corresponded more to a quiet office for noise level equivalents and to a busy restaurant for peak noise levels during both P1 and P2. Guidelines decreased the noise level equivalent (P1, 51.3 dB; P2, 48.3 dB), peak noise level (P1, 74.9 dB; P2, 70.8 dB), and the number of acoustic identified alarms (P1, 22.1 dB; P2, 15.8 dB) during P2. The night light levels were low during both periods, and lowering the light levels induced a greater variation of light, which may impair sleep quality. All measured noise levels were high during both periods, which could contribute to sleep disturbance, and the implementation of guidelines significantly lowers some important noise levels. The background noise level was unchanged.

Co-regulation of dark and light reactions in three biochemical subtypes of C(4) species.

PubMed

Kiirats, Olavi; Kramer, David M; Edwards, Gerald E

2010-08-01

Regulation of light harvesting in response to changes in light intensity, CO(2) and O(2) concentration was studied in C(4) species representing three different metabolic subtypes: Sorghum bicolor (NADP-malic enzyme), Amaranthus edulis (NAD-malic enzyme), and Panicum texanum (PEP-carboxykinase). Several photosynthetic parameters were measured on the intact leaf level including CO(2) assimilation rates, O(2) evolution, photosystem II activities, thylakoid proton circuit and dissipation of excitation energy. Gross rates of O(2) evolution (J(O)₂'), measured by analysis of chlorophyll fluorescence), net rates of O(2) evolution and CO(2) assimilation responded in parallel to changes in light and CO(2) levels. The C(4) subtypes had similar energy requirements for photosynthesis since there were no significant differences in maximal quantum efficiencies for gross rates of O(2) evolution (average value = 0.072 O(2)/quanta absorbed, approximately 14 quanta per O(2) evolved). At saturating actinic light intensities, when photosynthesis was suppressed by decreasing CO(2), ATP synthase proton conductivity (g (H) (+)) responded strongly to changes in electron flow, decreasing linearly with J(O)₂', which was previously observed in C(3) plants. It is proposed that g (H) (+) is controlled at the substrate level by inorganic phosphate availability. The results suggest development of nonphotochemical quenching in C(4) plants is controlled by a decrease in g (H) (+), which causes an increase in proton motive force by restricting proton efflux from the lumen, rather than by cyclic or pseudocyclic electron flow.

Ambient illumination switches contrast preference of specific retinal processing streams

PubMed Central

Pearson, James T.

2015-01-01

Contrast, a fundamental feature of visual scenes, is encoded in a distributed manner by ∼20 retinal ganglion cell (RGC) types, which stream visual information to the brain. RGC types respond preferentially to positive (ONpref) or negative (OFFpref) contrast and differ in their sensitivity to preferred contrast and responsiveness to nonpreferred stimuli. Vision operates over an enormous range of mean light levels. The influence of ambient illumination on contrast encoding across RGC types is not well understood. Here, we used large-scale multielectrode array recordings to characterize responses of mouse RGCs under lighting conditions spanning five orders in brightness magnitude. We identify three functional RGC types that switch contrast preference in a luminance-dependent manner (Sw1-, Sw2-, and Sw3-RGCs). As ambient illumination increases, Sw1- and Sw2-RGCs shift from ONpref to OFFpref and Sw3-RGCs from OFFpref to ONpref. In all cases, transitions in contrast preference are reversible and track light levels. By mapping spatiotemporal receptive fields at different mean light levels, we find that changes in input from ON and OFF pathways in receptive field centers underlie shifts in contrast preference. Sw2-RGCs exhibit direction-selective responses to motion stimuli. Despite changing contrast preference, direction selectivity of Sw2-RGCs and other RGCs as well as orientation-selective responses of RGCs remain stable across light levels. PMID:25995351

Herbivores and nutrients control grassland plant diversity via light limitation

USGS Publications Warehouse

Borer, Elizabeth T.; Seabloom, Eric W.; Gruner, Daniel S.; Harpole, W. Stanley; Hillebrand, Helmut; Lind, Eric M.; Alder, Peter B.; Alberti, Juan; Anderson, T. Michael; Bakker, Jonathan D.; Biederman, Lori; Blumenthal, Dana; Brown, Cynthia S.; Brudvig, Lars A.; Buckley, Yvonne M.; Cadotte, Marc; Chu, Cheng-Jin; Cleland, Elsa E.; Crawley, Michael J.; Daleo, Pedro; Damschen, Ellen Ingman; Davies, Kendi F.; DeCrappeo, Nicole M.; Du, Guozhen; Firn, Jennifer; Hautier, Yann; Heckman, Robert W.; Hector, Andy; HilleRisLambers, Janneke; Iribarne, Oscar; Klein, Julia A.; Knops, Johannes M.H.; La Pierre, Kimberly J.; Leakey, Andrew D.B.; Li, Wei; MacDougall, Andrew S.; McCulley, Rebecca L.; Melbourne, Brett A.; Mitchell, Charles E.; Moore, Joslin L.; Mortensen, Brent; O'Halloran, Lydia R.; Orrock, John L.; Pascual, Jesús; Prober, Suzanne M.; Pyke, David A.; Risch, Anita C.; Schuetz, Martin; Smith, Melinda D.; Stevens, Carly J.; Sullivan, Lauren L.; Williams, Ryan J.; Wragg, Peter D.; Wright, Justin P.; Yang, Louie H.

2014-01-01

Human alterations to nutrient cycles and herbivore communities are affecting global biodiversity dramatically. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.

Herbivores and nutrients control grassland plant diversity via light limitation.

PubMed

Borer, Elizabeth T; Seabloom, Eric W; Gruner, Daniel S; Harpole, W Stanley; Hillebrand, Helmut; Lind, Eric M; Adler, Peter B; Alberti, Juan; Anderson, T Michael; Bakker, Jonathan D; Biederman, Lori; Blumenthal, Dana; Brown, Cynthia S; Brudvig, Lars A; Buckley, Yvonne M; Cadotte, Marc; Chu, Chengjin; Cleland, Elsa E; Crawley, Michael J; Daleo, Pedro; Damschen, Ellen I; Davies, Kendi F; DeCrappeo, Nicole M; Du, Guozhen; Firn, Jennifer; Hautier, Yann; Heckman, Robert W; Hector, Andy; HilleRisLambers, Janneke; Iribarne, Oscar; Klein, Julia A; Knops, Johannes M H; La Pierre, Kimberly J; Leakey, Andrew D B; Li, Wei; MacDougall, Andrew S; McCulley, Rebecca L; Melbourne, Brett A; Mitchell, Charles E; Moore, Joslin L; Mortensen, Brent; O'Halloran, Lydia R; Orrock, John L; Pascual, Jesús; Prober, Suzanne M; Pyke, David A; Risch, Anita C; Schuetz, Martin; Smith, Melinda D; Stevens, Carly J; Sullivan, Lauren L; Williams, Ryan J; Wragg, Peter D; Wright, Justin P; Yang, Louie H

2014-04-24

Human alterations to nutrient cycles and herbivore communities are affecting global biodiversity dramatically. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.

Protein oxidative changes in whole and skim milk after ultraviolet or fluorescent light exposure.

PubMed

Scheidegger, D; Pecora, R P; Radici, P M; Kivatinitz, S C

2010-11-01

We investigated how protein changes occur, at the primary or higher structural levels, when proteins are exposed to UV or fluorescent (FL) light while in the complex matrix, milk. Whole milk (WM) or skim milk (SM) samples were exposed to FL or UV light from 0 to 24h at 4°C. Protein oxidation was evaluated by the formation of protein carbonyls (PC), dityrosine bond (DiTyr), and changes in molecular weight (protein fragmentation and polymerization). Oxidative changes in AA residues were measured by PC. Dityrosine and N'-formylkynurenine (NFK), a carbonylation derivative of Trp, were measured by fluorometry. Protein carbonyls increased as a function of irradiation time for both WM and SM. The initial rate for PC formation by exposure to FL light (0.25 or 0.27 nmol/h for WM and SM, respectively) was slower than that following exposure to UV light (1.95 or 1.20 nmol/h, respectively). The time course of NFK formation resembled that of PC. After 24h of UV exposure, SM had significantly higher levels of NFK than did WM. In contrast, WM samples irradiated with UV had higher levels of DiTyr than did SM samples, indicating different molecular pathways. The formation of intra- or intermolecular DiTyr bonds could be indicative of changes in the tertiary structure or oligomerization of proteins. The existence of NFK suggests the occurrence of protein fragmentation. Thus, proteolysis and oligomerization were analyzed by sodium dodecyl sulfate-PAGE. After 24h of exposing WM to UV or FL light, all the proteins were affected by both types of light, as evidenced by loss of material in most of the bands. Aggregates were produced only by UV irradiation. Hydrolysis by pepsin and enzyme-induced coagulation by rennet were performed to evaluate altered biological properties of the oxidized proteins. No effect on pepsin digestion or rennet coagulation was found in irradiated SM or WM. The oxidative status of proteins in milk and dairy products is of interest to the dairy industry and consumers. These findings provide knowledge that could be useful in determining the optimal lighting conditions in the dairy industry in general and in cheese making in particular. Copyright © 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Seagrass canopy photosynthetic response is a function of canopy density and light environment: a model for Amphibolis griffithii.

PubMed

Hedley, John D; McMahon, Kathryn; Fearns, Peter

2014-01-01

A three-dimensional computer model of canopies of the seagrass Amphibolis griffithii was used to investigate the consequences of variations in canopy structure and benthic light environment on leaf-level photosynthetic saturation state. The model was constructed using empirical data of plant morphometrics from a previously conducted shading experiment and validated well to in-situ data on light attenuation in canopies of different densities. Using published values of the leaf-level saturating irradiance for photosynthesis, results show that the interaction of canopy density and canopy-scale photosynthetic response is complex and non-linear, due to the combination of self-shading and the non-linearity of photosynthesis versus irradiance (P-I) curves near saturating irradiance. Therefore studies of light limitation in seagrasses should consider variation in canopy structure and density. Based on empirical work, we propose a number of possible measures for canopy scale photosynthetic response that can be plotted to yield isoclines in the space of canopy density and light environment. These plots can be used to interpret the significance of canopy changes induced as a response to decreases in the benthic light environment: in some cases canopy thinning can lead to an equivalent leaf level light environment, in others physiological changes may also be required but these alone may be inadequate for canopy survival. By providing insight to these processes the methods developed here could be a valuable management tool for seagrass conservation during dredging or other coastal developments.

Seagrass Canopy Photosynthetic Response Is a Function of Canopy Density and Light Environment: A Model for Amphibolis griffithii

PubMed Central

Hedley, John D.; McMahon, Kathryn; Fearns, Peter

2014-01-01

A three-dimensional computer model of canopies of the seagrass Amphibolis griffithii was used to investigate the consequences of variations in canopy structure and benthic light environment on leaf-level photosynthetic saturation state. The model was constructed using empirical data of plant morphometrics from a previously conducted shading experiment and validated well to in-situ data on light attenuation in canopies of different densities. Using published values of the leaf-level saturating irradiance for photosynthesis, results show that the interaction of canopy density and canopy-scale photosynthetic response is complex and non-linear, due to the combination of self-shading and the non-linearity of photosynthesis versus irradiance (P-I) curves near saturating irradiance. Therefore studies of light limitation in seagrasses should consider variation in canopy structure and density. Based on empirical work, we propose a number of possible measures for canopy scale photosynthetic response that can be plotted to yield isoclines in the space of canopy density and light environment. These plots can be used to interpret the significance of canopy changes induced as a response to decreases in the benthic light environment: in some cases canopy thinning can lead to an equivalent leaf level light environment, in others physiological changes may also be required but these alone may be inadequate for canopy survival. By providing insight to these processes the methods developed here could be a valuable management tool for seagrass conservation during dredging or other coastal developments. PMID:25347849

Natural Genetic Variation for Acclimation of Photosynthetic Light Use Efficiency to Growth Irradiance in Arabidopsis1[OPEN

PubMed Central

Harbinson, Jeremy

2015-01-01

Plants are known to be able to acclimate their photosynthesis to the level of irradiance. Here, we present the analysis of natural genetic variation for photosynthetic light use efficiency (ΦPSII) in response to five light environments among 12 genetically diverse Arabidopsis (Arabidopsis thaliana) accessions. We measured the acclimation of ΦPSII to constant growth irradiances of four different levels (100, 200, 400, and 600 µmol m−2 s−1) by imaging chlorophyll fluorescence after 24 d of growth and compared these results with acclimation of ΦPSII to a step-wise change in irradiance where the growth irradiance was increased from 100 to 600 µmol m−2 s−1 after 24 d of growth. Genotypic variation for ΦPSII is shown by calculating heritability for the short-term ΦPSII response to different irradiance levels as well as for the relation of ΦPSII measured at light saturation (a measure of photosynthetic capacity) to growth irradiance level and for the kinetics of the response to a step-wise increase in irradiance from 100 to 600 µmol m−2 s−1. A genome-wide association study for ΦPSII measured 1 h after a step-wise increase in irradiance identified several new candidate genes controlling this trait. In conclusion, the different photosynthetic responses to a changing light environment displayed by different Arabidopsis accessions are due to genetic differences, and we have identified candidate genes for the photosynthetic response to an irradiance change. The genetic variation for photosynthetic acclimation to irradiance found in this study will allow future identification and analysis of the causal genes for the regulation of ΦPSII in plants. PMID:25670817

Night-time lighting alters the composition of marine epifaunal communities

PubMed Central

Davies, Thomas W.; Coleman, Matthew; Griffith, Katherine M.; Jenkins, Stuart R.

2015-01-01

Marine benthic communities face multiple anthropogenic pressures that compromise the future of some of the most biodiverse and functionally important ecosystems in the world. Yet one of the pressures these ecosystems face, night-time lighting, remains unstudied. Light is an important cue in guiding the settlement of invertebrate larvae, and altering natural regimes of nocturnal illumination could modify patterns of recruitment among sessile epifauna. We present the first evidence of night-time lighting changing the composition of temperate epifaunal marine invertebrate communities. Illuminating settlement surfaces with white light-emitting diode lighting at night, to levels experienced by these communities locally, both inhibited and encouraged the colonization of 39% of the taxa analysed, including three sessile and two mobile species. Our results indicate that ecological light pollution from coastal development, shipping and offshore infrastructure could be changing the composition of marine epifaunal communities. PMID:25926694

Interrelationships among light, photosynthesis and nitrogen in the crown of mature Pinus contorta ssp. latifolia

Treesearch

A. W. Schoettle; W. K. Smith

1999-01-01

Scaling leaf-level measurements to estimate carbon gain of entire leaf crowns or canopies requires an understanding of the distribution of photosynthetic capacity and corresponding light microenvironments within a crown. We have compared changes in the photosynthetic light response and nitrogen (N) content (per unit leaf area) of Pinus contorta Dougl. ssp. latifolia...

Levels of Arabidopsis thaliana Leaf Phosphatidic Acids, Phosphatidylserines, and Most Trienoate-Containing Polar Lipid Molecular Species Increase during the Dark Period of the Diurnal Cycle.

PubMed

Maatta, Sara; Scheu, Brad; Roth, Mary R; Tamura, Pamela; Li, Maoyin; Williams, Todd D; Wang, Xuemin; Welti, Ruth

2012-01-01

Previous work has demonstrated that plant leaf polar lipid fatty acid composition varies during the diurnal (dark-light) cycle. Fatty acid synthesis occurs primarily during the light, but fatty acid desaturation continues in the absence of light, resulting in polyunsaturated fatty acids reaching their highest levels toward the end of the dark period. In this work, Arabidopsis thaliana were grown at constant (21°C) temperature with 12-h light and 12-h dark periods. Collision induced dissociation time-of-flight mass spectrometry (MS) demonstrated that 16:3 and 18:3 fatty acid content in membrane lipids of leaves are higher at the end of the dark than at the end of the light period, while 16:1, 16:2, 18:0, and 18:1 content are higher at the end of the light period. Lipid profiling of membrane galactolipids, phospholipids, and lysophospholipids by electrospray ionization triple quadrupole MS indicated that the monogalactosyldiacylglycerol, phosphatidylglycerol, and phosphatidylcholine classes include molecular species whose levels are highest at end of the light period and others that are highest at the end of the dark period. The levels of phosphatidic acid (PA) and phosphatidylserine classes were higher at the end of the dark period, and molecular species within these classes either followed the class pattern or were not significantly changed in the diurnal cycle. Phospholipase D (PLD) is a family of enzymes that hydrolyzes phospholipids to produce PA. Analysis of several PLD mutant lines suggests that PLDζ2 and possibly PLDα1 may contribute to diurnal cycling of PA. The polar lipid compositional changes are considered in relation to recent data that demonstrate phosphatidylcholine acyl editing.

The effects of gamma radiation, UV and visible light on ATP levels in yeast cells depend on cellular melanization.

PubMed

Bryan, Ruth; Jiang, Zewei; Friedman, Matthew; Dadachova, Ekaterina

2011-10-01

Previously we have shown that growth of melanized fungi is stimulated by low levels of gamma radiation. The goal of this study was to examine the effects of visible light, UV light, and gamma radiation on the energy level (ATP concentration) in melanized Cryptococcus neoformans cells. Melanized C. neoformans cells as well as non-melanized controls were subjected to visible, UV or gamma radiation, and ATP was quantified by measuring the amount of light emitted by the ATP-dependent reaction of luciferase with luciferin. We found that all three forms of radiation led to a reduction in the ATP levels in melanized C. neoformans cells. This points to a universal melanin-related mechanism underlying observation of ATP decrease in irradiated melanized cells. In contrast, in non-melanized cells visible light led to increase in ATP levels; gamma radiation did not cause any changes while UV exposure resulted in some ATP decrease, however, much less pronounced than in melanized cells. Copyright © 2011 British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Enhancing the efficacy of AREDS antioxidants in light-induced retinal degeneration

PubMed Central

Wong, Paul; Markey, M.; Rapp, C. M.; Darrow, R. M.; Ziesel, A.

2017-01-01

Purpose Light-induced photoreceptor cell degeneration and disease progression in age-related macular degeneration (AMD) involve oxidative stress and visual cell loss, which can be prevented, or slowed, by antioxidants. Our goal was to test the protective efficacy of a traditional Age-related Eye Disease Study antioxidant formulation (AREDS) and AREDS combined with non-traditional antioxidants in a preclinical animal model of photooxidative retinal damage. Methods Male Sprague-Dawley rats were reared in a low-intensity (20 lux) or high-intensity (200 lux) cyclic light environment for 6 weeks. Some animals received a daily dietary supplement consisting of a small cracker infused with an AREDS antioxidant mineral mixture, AREDS antioxidants minus zinc, or zinc oxide alone. Other rats received AREDS combined with a detergent extract of the common herb rosemary, AREDS plus carnosic acid, zinc oxide plus rosemary, or rosemary alone. Antioxidant efficacy was determined by measuring retinal DNA levels 2 weeks after 6 h of intense exposure to white light (9,000 lux). Western blotting was used to determine visual cell opsin and arrestin levels following intense light treatment. Rhodopsin regeneration was determined after 1 h of exposure to light. Gene array analysis was used to determine changes in the expression of retinal genes resulting from light rearing environment or from antioxidant supplementation. Results Chronic high-intensity cyclic light rearing resulted in lower levels of rod and cone opsins, retinal S-antigen (S-ag), and medium wavelength cone arrestin (mCAR) than found for rats maintained in low cyclic light. However, as determined by retinal DNA, and by residual opsin and arrestin levels, 2 weeks after acute photooxidative damage, visual cell loss was greater in rats reared in low cyclic light. Retinal damage decreased with AREDS plus rosemary, or with zinc oxide plus rosemary whereas AREDS alone and zinc oxide alone (at their daily recommended levels) were both ineffective. One week of supplemental AREDS plus carnosic acid resulted in higher levels of rod and cone cell proteins, and higher levels of retinal DNA than for AREDS alone. Rhodopsin regeneration was unaffected by the rosemary treatment. Retinal gene array analysis showed reduced expression of medium- wavelength opsin 1 and arrestin C in the high-light reared rats versus the low-light rats. The transition of rats from low cyclic light to a high cyclic light environment resulted in the differential expression of 280 gene markers, enriched for genes related to inflammation, apoptosis, cytokine, innate immune response, and receptors. Rosemary, zinc oxide plus rosemary, and AREDS plus rosemary suppressed 131, 241, and 266 of these genes (respectively) in high-light versus low-light animals and induced a small subset of changes in gene expression that were independent of light rearing conditions. Conclusions Long-term environmental light intensity is a major determinant of retinal gene and protein expression, and of visual cell survival following acute photooxidative insult. Rats preconditioned by high-light rearing exhibit lower levels of cone opsin mRNA and protein, and lower mCAR protein, than low-light reared animals, but greater retention of retinal DNA and proteins following photooxidative damage. Rosemary enhanced the protective efficacy of AREDS and led to the greatest effect on the retinal genome in animals reared in high environmental light. Chronic administration of rosemary antioxidants may be a useful adjunct to the therapeutic benefit of AREDS in slowing disease progression in AMD. PMID:29062223

Can dendritic cells see light?

NASA Astrophysics Data System (ADS)

Chen, Aaron C.-H.; Huang, Ying-Ying; Sharma, Sulbha K.; Hamblin, Michael R.

2010-02-01

There are many reports showing that low-level light/laser therapy (LLLT) can enhance wound healing, upregulate cell proliferation and has anti-apoptotic effects by activating intracellular protective genes. In the field of immune response study, it is not known with any certainty whether light/laser is proinflammatory or anti-inflammatory. Increasingly in recent times dendritic cells have been found to play an important role in inflammation and the immunological response. In this study, we try to look at the impact of low level near infrared light (810-nm) on murine bone-marrow derived dendritic cells. Changes in surface markers, including MHC II, CD80 and CD11c and the secretion of interleukins induced by light may provide additional evidence to reveal the mystery of how light affects the maturation of dendritic cells as well how these light-induced mature dendritic cells would affect the activation of adaptive immune response.

Policy Change and Private Higher Education Development: A Case Study

ERIC Educational Resources Information Center

Zhao, Xiantong

2014-01-01

This research aims to explore the development of private higher education and related policy changes in China in the light of Foucault's notion of governmentality in neoliberal China. Essentially it is a synthesis of macro-level and micro-level analysis. The researcher examines policy development in combination with wide social, political and…

Light, time, and the physiology of biotic response to rapid climate change in animals.

PubMed

Bradshaw, William E; Holzapfel, Christina M

2010-01-01

Examination of temperate and polar regions of Earth shows that the nonbiological world is exquisitely sensitive to the direct effects of temperature, whereas the biological world is largely organized by light. Herein, we discuss the use of day length by animals at physiological and genetic levels, beginning with a comparative experimental study that shows the preeminent role of light in determining fitness in seasonal environments. Typically, at seasonally appropriate times, light initiates a cascade of physiological events mediating the input and interpretation of day length to the output of specific hormones that ultimately determine whether animals prepare to develop, reproduce, hibernate, enter dormancy, or migrate. The mechanisms that form the basis of seasonal time keeping and their adjustment during climate change are reviewed at the physiological and genetic levels. Future avenues for research are proposed that span basic questions from how animals transition from dependency on tropical cues to temperate cues during range expansions, to more applied questions of species survival and conservation biology during periods of climatic stress.

Variation in sensitivity of large benthic Foraminifera to the combined effects of ocean warming and local impacts.

PubMed

Prazeres, Martina; Roberts, T Edward; Pandolfi, John M

2017-03-23

Large benthic foraminifera (LBF) are crucial marine calcifiers in coral reefs, and sensitive to environmental changes. Yet, many species successfully colonise a wide range of habitats including highly fluctuating environments. We tested the combined effects of ocean warming, local impacts and different light levels on populations of the common LBF Amphistegina lobifera collected along a cross-shelf gradient of temperature and nutrients fluctuations. We analysed survivorship, bleaching frequency, chlorophyll a content and fecundity. Elevated temperature and nitrate significantly reduced survivorship and fecundity of A. lobifera across populations studied. This pattern was exacerbated when combined with below optimum light levels. Inshore populations showed a consistent resistance to increased temperature and nitrate levels, but all populations studied were significantly affected by light reduction. These findings demonstrated the capacity of some populations of LBF to acclimate to local conditions; nonetheless improvements in local water quality can ultimately ameliorate effects of climate change in local LBF populations.

Ultrafast myoglobin structural dynamics observed with an X-ray free-electron laser

DOE PAGES

Levantino, Matteo; Schirò, Giorgio; Lemke, Henrik Till; ...

2015-04-02

Light absorption can trigger biologically relevant protein conformational changes. The light induced structural rearrangement at the level of a photoexcited chromophore is known to occur in the femtosecond timescale and is expected to propagate through the protein as a quake-like intramolecular motion. Here we report direct experimental evidence of such ‘proteinquake’ observed in myoglobin through femtosecond X-ray solution scattering measurements performed at the Linac Coherent Light Source X-ray free-electron laser. An ultrafast increase of myoglobin radius of gyration occurs within 1 picosecond and is followed by a delayed protein expansion. As the system approaches equilibrium it undergoes damped oscillations withmore » a ~3.6-picosecond time period. Our results unambiguously show how initially localized chemical changes can propagate at the level of the global protein conformation in the picosecond timescale.« less

Changes in blood glucose level during and after light sedations using propofol-fentanyl and midazolam-fentanyl in diabetic patients who underwent cataract surgery.

PubMed

Khalighinejad, Pooyan; Rahimi, Mojtaba; Naghibi, Khosro; Niknam, Negar

2015-01-01

Surgeries may trigger the stress response which leads to changes in blood glucose level, and studies suggest that different sedation and anesthesia methods have different effects on blood glucose level. The aim of this study was to investigate changes of blood glucose levels in diabetic patients and compare them in two sedation methods of propofol + fentanyl and midazolam + fentanyl. Totally, 80 diabetic candidates for cataract surgery who had all the inclusion criteria, underwent cataract surgery using two methods of propofol (1 mg/kg/h) + fentanyl (2 μg/kg) (Group P) and midazolam (0.03 mg/kg) + fentanyl (2 μg/kg) (Group M) for light sedation. In the end, 70 patients (Group P n = 35 and Group M n = 35) remained in the study. Patients' blood glucose levels, vital signs, and hemodynamic data were assessed 30 min prior to the surgery, each 15 min during surgery and at the end of surgery. Hemodynamic parameters did not have a statistically significant difference between the two groups mean blood glucose level in Group M was 149.15 mg/dl and in Group P was 149.2 mg/dl, and based on repeated measures analysis of variance test, significant differences were not observed between the two groups (P = 0.99). T-test showed no significant differences in the blood glucose level at any time of the study between the two groups. Light sedation methods of propofol + fentanyl and midazolam + fentanyl did not have any differences in alteration of blood glucose level.

Occultation Lightcurves for Selected Pluto Volatile Transport Models

NASA Astrophysics Data System (ADS)

Young, L. A.

2004-11-01

The stellar occultations by Pluto in 1988 and 2002 are demonstrably sensitive to changes in Pluto's atmosphere near one microbar (Elliot and Young 1992, AJ 103, 991; Elliot et al. 2003, Nature 424, 165; Sicardy 2003, Nature 424, 168). However, Pluto volatile-transport models focus on the changes in the atmospheric pressure at the surface (e.g., Hansen and Paige 1996, Icarus 20, 247; Stansberry and Yelle 1999, Icarus 141, 299). What's lacking is a connection between predictions about the surface properties and either temperature and pressure profiles measurable from stellar occultations, or the occultation light curve morphology itself. Radiative-conductive models can illuminate this connection. I will illustrate how Pluto's changing surface pressure, temperature, and heliocentric distance may affect occultation light curves for a selection of existing volatile transport models. Changes in the light curve include the presence or absence of an observable ``kink'' (or departure from an isothermal light curve), the appearance of non-zero minimum flux levels, and the detectability of the solid surface. These light curves can serve as examples of what we may anticipate during the upcoming Pluto occultation season, as Pluto crosses the galactic plane.

The ecological impact of city lighting scenarios: exploring gap crossing thresholds for urban bats.

PubMed

Hale, James D; Fairbrass, Alison J; Matthews, Thomas J; Davies, Gemma; Sadler, Jon P

2015-02-02

As the global population urbanizes, dramatic changes are expected in city lighting and the urban form, which may threaten the functioning of urban ecosystems and the services they deliver. However, little is known about the ecological impact of lighting in different urban contexts. Movement is an important ecological process that can be disrupted by artificial lighting. We explored the impact of lighting on gap crossing for Pipistrellus pipistrellus, a species of bat (Chiroptera) common within UK cities. We aimed to determine whether the probability of crossing gaps in tree cover varied with crossing distance and lighting level, through stratified field surveys. We then used the resulting data on barrier thresholds to model the landscape resistance due to lighting across an entire city and explored the potential impact of scenarios for future changes to street lighting. The level of illumination required to create a barrier effect reduced as crossing distance increased. For those gaps where crossing was recorded, bats selected the darker parts of gaps. Heavily built parts of the case study city were associated with large and brightly lit gaps, and spatial models indicate movement would be highly restricted in these areas. Under a scenario for brighter street lighting, the area of accessible land cover was further reduced in heavily built parts of the city. We believe that this is the first study to demonstrate how lighting may create resistance to species movement throughout an entire city. That connectivity in urban areas is being disrupted for a relatively common species raises questions about the impacts on less tolerant groups and the resilience of bat communities in urban centres. However, this mechanistic approach raises the possibility that some ecological function could be restored in these areas through the strategic dimming of lighting and narrowing of gaps. © 2015 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

The interplay between cytokinins and light during senescence in detached Arabidopsis leaves.

PubMed

Janečková, Helena; Husičková, Alexandra; Ferretti, Ursula; Prčina, Maroš; Pilařová, Eva; Plačková, Lenka; Pospíšil, Pavel; Doležal, Karel; Špundová, Martina

2018-05-09

Light and cytokinins are known to be the key players in the regulation of plant senescence. In detached leaves, the retarding effect of light on senescence is well described; however, it is not clear to what extent is this effect connected with changes in endogenous cytokinin levels. We have performed a detailed analysis of changes in endogenous content of 29 cytokinin forms in detached leaves of Arabidopsis thaliana (wild-type and three cytokinin receptor double-mutants). Leaves were kept under different light conditions and changes in cytokinin content were correlated with changes in chlorophyll content, efficiency of photosystem II photochemistry and lipid peroxidation. In leaves kept in darkness we have observed decreased content of the most abundant cytokinin free bases and ribosides, but the content of cis-zeatin increased, which indicates the role of this cytokinin in the maintenance of basal leaf viability. Our findings underscore the importance of light conditions on the content of specific cytokinins, especially N 6 -(Δ 2 -isopentenyl)adenine. Based on our results, we present a scheme summarizing the contribution of the main active forms of cytokinins, cytokinin receptors and light to senescence regulation. We conclude that light can compensate the disrupted cytokinin signaling in detached leaves. This article is protected by copyright. All rights reserved.

Photodynamic therapy (PDT) as a biological modifier

NASA Astrophysics Data System (ADS)

Obochi, Modestus; Tao, Jing-Song; Hunt, David W. C.; Levy, Julia G.

1996-04-01

The capacity of photosensitizers and light to ablate cancerous tissues and unwanted neovasculature constitutes the classical application of photodynamic therapy (PDT). Cell death results from either necrotic or apoptotic processes. The use of photosensitizers and light at doses which do not cause death has been found to affect changes in certain cell populations which profoundly effect their expression of cell surface molecules and secretion of cytokines, thereby altering the functional attributes of the treated cells. Cells of the immune system and the skin may be sensitive to modulation by 'sub-lethal PDT.' Ongoing studies have been conducted to assess, at the molecular level, changes in both lymphocytes and epidermal cells (EC) caused by treatment with low levels of benzoporphyrin derivative monoacid ring A (BPD) (a photosensitizer currently in clinical trials for cancer, psoriasis, endometriosis and age-related macular degeneration) and light. Treatment of skin with BPD and light, at levels which significantly enhanced the length of murine skin allograft acceptance, have been found to down-regulate the expression of Langerhans cell (LC) surface antigen molecules [major histocompatibility complex (MHC) class II and intracellular adhesion molecule (ICAM)-1] and the formation of some cytokines (tumor necrosis factor-alpha (TNF- (alpha) ).

Differential expression of melanopsin mRNA and protein in Brown Norwegian rats.

PubMed

Hannibal, Jens; Georg, Birgitte; Fahrenkrug, Jan

2013-01-01

Melanopsin is expressed in a subpopulation of retinal ganglion cells rendering these cells intrinsically photosensitive (ipRGCs). The ipRGCs are the primary RGCs mediating light entrainment of the circadian clock and control of the pupillary light reflex, light regulated melatonin secretion and negative masking behaviour. Previous studies have demonstrated that melanopsin expression in albino rats is regulated by light and darkness. The present study was undertaken to study the influence of light and darkness during the circadian day and after extended periods of constant light and darkness on melanopsin expression in the pigmented retina of the Brown Norwegian rat (Rattus norvegicus). The diurnal and circadian expressions were examined in retinal extracts from rats euthanized every 4 h during a 24 h light/dark (LD) and a 24 h dark cycle (DD) using quantitative real-time PCR and Western blotting. To study whether light regulates melanopsin expression, rats were sacrificed after being placed in either constant light (LL) or darkness for 3 or 21 d. Flat mount retinas from animals kept during either LL or DD were also examined by immunohistochemistry. Melanopsin mRNA expression displayed a significant rhythmic change during the LD cycle with peak expression around dusk and nadir at dawn. Melanopsin protein also changed over the LD cycle with peak expression at the end of the night and nadir at dusk. Rhythmic expression of melanopsin mRNA but not melanopsin protein was found in constant darkness. After 3 or 21 d in either LL or DD melanopsin mRNA expression was unaltered. Melanopsin protein was at the same high level after 3 and 21 d in DD, whereas a significant decrease was found after prolonging the light period for 3 or 21 d. The change in melanopsin protein was primarily due to change in immunoreactivity in the dendritic processes. In conclusion we found that light and darkness are important for regulation of melanopsin protein expression whereas input from a retinal networks regulates melanopsin mRNA expression. It is likely to speculate that altered level of melanopsin is one way in which the retina adapts to environmental light and darkness conditions ensuring optimal light sensitivity for the transmission to the brain. Copyright © 2012 Elsevier Ltd. All rights reserved.

Light at night disrupts nocturnal rest and elevates glucocorticoids at cool color temperatures.

PubMed

Alaasam, Valentina J; Duncan, Richard; Casagrande, Stefania; Davies, Scott; Sidher, Abhijaat; Seymoure, Brett; Shen, Yantao; Zhang, Yong; Ouyang, Jenny Q

2018-05-15

Nighttime light pollution is quickly becoming a pervasive, global concern. Since the invention and proliferation of light-emitting diodes (LED), it has become common for consumers to select from a range of color temperatures of light with varying spectra. Yet, the biological impacts of these different spectra on organisms remain unclear. We tested if nighttime illumination of LEDs, at two commercially available color temperatures (3000 and 5000 K) and at ecologically relevant illumination levels affected body condition, food intake, locomotor activity, and glucocorticoid levels in zebra finches (Taeniopygia guttata). We found that individuals exposed to 5000 K light had higher rates of nighttime activity (peaking after 1 week of treatment) compared to 3000 K light and controls (no nighttime light). Birds in the 5000 K treatment group also had increased corticosterone levels from pretreatment levels compared to 3000 K and control groups but no changes in body condition or food intake. Individuals that were active during the night did not consequently decrease daytime activity. This study adds to the growing evidence that the spectrum of artificial light at night is important, and we advocate the use of nighttime lighting with warmer color temperatures of 3000 K instead of 5000 K to decrease energetic costs for avian taxa. © 2018 Wiley Periodicals, Inc.

Smartphone based point-of-care detector of urine albumin

NASA Astrophysics Data System (ADS)

Cmiel, Vratislav; Svoboda, Ondrej; Koscova, Pavlina; Provaznik, Ivo

2016-03-01

Albumin plays an important role in human body. Its changed level in urine may indicate serious kidney disorders. We present a new point-of-care solution for sensitive detection of urine albumin - the miniature optical adapter for iPhone with in-built optical filters and a sample slot. The adapter exploits smart-phone flash to generate excitation light and camera to measure the level of emitted light. Albumin Blue 580 is used as albumin reagent. The proposed light-weight adapter can be produced at low cost using a 3D printer. Thus, the miniaturized detector is easy to use out of lab.

Shedding light on light: benefits of anthropogenic illumination to a nocturnally foraging shorebird.

PubMed

Dwyer, Ross G; Bearhop, Stuart; Campbell, Hamish A; Bryant, David M

2013-03-01

Intertidal habitats provide important feeding areas for migratory shorebirds. Anthropogenic developments along coasts can increase ambient light levels at night across adjacent inter-tidal zones. Here, we report the effects of elevated nocturnal light levels upon the foraging strategy of a migratory shorebird (common redshank Tringa totanus) overwintering on an industrialised estuary in Northern Europe. To monitor behaviour across the full intertidal area, individuals were located by day and night using VHF transmitters, and foraging behaviour was inferred from inbuilt posture sensors. Natural light was scored using moon-phase and cloud cover information and nocturnal artificial light levels were obtained using geo-referenced DMSP/OLS night-time satellite imagery at a 1-km resolution. Under high illumination levels, the commonest and apparently preferred foraging behaviour was sight-based. Conversely, birds feeding in areas with low levels of artificial light had an elevated foraging time and fed by touch, but switched to visual rather than tactile foraging behaviour on bright moonlit nights in the absence of cloud cover. Individuals occupying areas which were illuminated continuously by lighting from a large petrochemical complex invariably exhibited a visually based foraging behaviour independently of lunar phase and cloud cover. We show that ambient light levels affect the timing and distribution of foraging opportunities for redshank. We argue that light emitted from an industrial complex improved nocturnal visibility. This allowed sight-based foraging in place of tactile foraging, implying both a preference for sight-feeding and enhanced night-time foraging opportunities under these conditions. The study highlights the value of integrating remotely sensed data and telemetry techniques to assess the effect of anthropogenic change upon nocturnal behaviour and habitat use. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

A gestalt account of lightness illusions.

PubMed

Gilchrist, Alan

2014-01-01

Illusions of lightness offer valuable clues to how lightness values are computed by the visual system. The traditional domain of lightness illusions must be expanded to include failures of constancy, as there is no distinction between these categories. Just as lightness is (relatively) constant in the face of changes in illumination level, so it is equally constant in the face of changes in background reflectance. Simultaneous lightness contrast, the most familiar lightness illusion, is fairly weak, and represents a failure of background-independent lightness constancy. It is argued that a combination of the highest-luminance rule of anchoring plus the Kardos idea of codetermination can account for most lightness illusions. Kardos suggested that the lightness value of a target surface is partly determined relative to the field of illumination (or framework) in which it is embedded, and partly relative to the neighboring field of illumination. Although Kardos did not apply his principle of codetermination to failures of background-independent constancy such as the simultaneous contrast illusion, this can be done rather easily by defining a framework as a perceptual group instead of identifying it strictly with an objective field of illumination.

Twisted molecular excitons as mediators for changing the angular momentum of light

NASA Astrophysics Data System (ADS)

Zang, Xiaoning; Lusk, Mark T.

2017-07-01

Molecules with CN or CN h symmetry can absorb quanta of optical angular momentum to generate twisted excitons with well-defined quasiangular momenta of their own. Angular momentum is conserved in such interactions at the level of a paraxial approximation for the light beam. A sequence of absorption events can thus be used to create a range of excitonic angular momenta. Subsequent decay can produce radiation with a single angular momentum equal to that accumulated. Such molecules can thus be viewed as mediators for changing the angular momentum of light. This sidesteps the need to exploit nonlinear light-matter interactions based on higher-order susceptibilities. A tight-binding paradigm is used to verify angular momentum conservation and demonstrate how it can be exploited to change the angular momentum of light. The approach is then extended to a time-dependent density functional theory setting where the key results are shown to hold in a many-body, multilevel setting.

Optimisation approaches for concurrent transmitted light imaging during confocal microscopy.

PubMed

Collings, David A

2015-01-01

The transmitted light detectors present on most modern confocal microscopes are an under-utilised tool for the live imaging of plant cells. As the light forming the image in this detector is not passed through a pinhole, out-of-focus light is not removed. It is this extended focus that allows the transmitted light image to provide cellular and organismal context for fluorescence optical sections generated confocally. More importantly, the transmitted light detector provides images that have spatial and temporal registration with the fluorescence images, unlike images taken with a separately-mounted camera. Because plants often provide difficulties for taking transmitted light images, with the presence of pigments and air pockets in leaves, this study documents several approaches to improving transmitted light images beginning with ensuring that the light paths through the microscope are correctly aligned (Köhler illumination). Pigmented samples can be imaged in real colour using sequential scanning with red, green and blue lasers. The resulting transmitted light images can be optimised and merged in ImageJ to generate colour images that maintain registration with concurrent fluorescence images. For faster imaging of pigmented samples, transmitted light images can be formed with non-absorbed wavelengths. Transmitted light images of Arabidopsis leaves expressing GFP can be improved by concurrent illumination with green and blue light. If the blue light used for YFP excitation is blocked from the transmitted light detector with a cheap, coloured glass filters, the non-absorbed green light will form an improved transmitted light image. Changes in sample colour can be quantified by transmitted light imaging. This has been documented in red onion epidermal cells where changes in vacuolar pH triggered by the weak base methylamine result in measurable colour changes in the vacuolar anthocyanin. Many plant cells contain visible levels of pigment. The transmitted light detector provides a useful tool for documenting and measuring changes in these pigments while maintaining registration with confocal imaging.

Exposure of tropical ecosystems to artificial light at night: Brazil as a case study.

PubMed

Freitas, Juliana Ribeirão de; Bennie, Jon; Mantovani, Waldir; Gaston, Kevin J

2017-01-01

Artificial nighttime lighting from streetlights and other sources has a broad range of biological effects. Understanding the spatial and temporal levels and patterns of this lighting is a key step in determining the severity of adverse effects on different ecosystems, vegetation, and habitat types. Few such analyses have been conducted, particularly for regions with high biodiversity, including the tropics. We used an intercalibrated version of the Defense Meteorological Satellite Program's Operational Linescan System (DMSP/OLS) images of stable nighttime lights to determine what proportion of original and current Brazilian vegetation types are experiencing measurable levels of artificial light and how this has changed in recent years. The percentage area affected by both detectable light and increases in brightness ranged between 0 and 35% for native vegetation types, and between 0 and 25% for current vegetation (i.e. including agriculture). The most heavily affected areas encompassed terrestrial coastal vegetation types (restingas and mangroves), Semideciduous Seasonal Forest, and Mixed Ombrophilous Forest. The existing small remnants of Lowland Deciduous and Semideciduous Seasonal Forests and of Campinarana had the lowest exposure levels to artificial light. Light pollution has not often been investigated in developing countries but our data show that it is an environmental concern.

Experimental illumination of natural habitat--an experimental set-up to assess the direct and indirect ecological consequences of artificial light of different spectral composition.

PubMed

Spoelstra, Kamiel; van Grunsven, Roy H A; Donners, Maurice; Gienapp, Phillip; Huigens, Martinus E; Slaterus, Roy; Berendse, Frank; Visser, Marcel E; Veenendaal, Elmar

2015-05-05

Artificial night-time illumination of natural habitats has increased dramatically over the past few decades. Generally, studies that assess the impact of artificial light on various species in the wild make use of existing illumination and are therefore correlative. Moreover, studies mostly focus on short-term consequences at the individual level, rather than long-term consequences at the population and community level-thereby ignoring possible unknown cascading effects in ecosystems. The recent change to LED lighting has opened up the exciting possibility to use light with a custom spectral composition, thereby potentially reducing the negative impact of artificial light. We describe here a large-scale, ecosystem-wide study where we experimentally illuminate forest-edge habitat with different spectral composition, replicated eight times. Monitoring of species is being performed according to rigid protocols, in part using a citizen-science-based approach, and automated where possible. Simultaneously, we specifically look at alterations in behaviour, such as changes in activity, and daily and seasonal timing. In our set-up, we have so far observed that experimental lights facilitate foraging activity of pipistrelle bats, suppress activity of wood mice and have effects on birds at the community level, which vary with spectral composition. Thus far, we have not observed effects on moth populations, but these and many other effects may surface only after a longer period of time. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

The Acclimation of Phaeodactylum tricornutum to Blue and Red Light Does Not Influence the Photosynthetic Light Reaction but Strongly Disturbs the Carbon Allocation Pattern

PubMed Central

Jungandreas, Anne; Schellenberger Costa, Benjamin; Jakob, Torsten; von Bergen, Martin; Baumann, Sven; Wilhelm, Christian

2014-01-01

Diatoms are major contributors to the aquatic primary productivity and show an efficient acclimation ability to changing light intensities. Here, we investigated the acclimation of Phaeodactylum tricornutum to different light quality with respect to growth rate, photosynthesis rate, macromolecular composition and the metabolic profile by shifting the light quality from red light (RL) to blue light (BL) and vice versa. Our results show that cultures pre-acclimated to BL and RL exhibited similar growth performance, photosynthesis rates and metabolite profiles. However, light shift experiments revealed rapid and severe changes in the metabolite profile within 15 min as the initial reaction of light acclimation. Thus, during the shift from RL to BL, increased concentrations of amino acids and TCA cycle intermediates were observed whereas during the BL to RL shift the levels of amino acids were decreased and intermediates of glycolysis accumulated. Accordingly, on the time scale of hours the RL to BL shift led to a redirection of carbon into the synthesis of proteins, whereas during the BL to RL shift an accumulation of carbohydrates occurred. Thus, a vast metabolic reorganization of the cells was observed as the initial reaction to changes in light quality. The results are discussed with respect to a putative direct regulation of cellular enzymes by light quality and by transcriptional regulation. Interestingly, the short-term changes in the metabolome were accompanied by changes in the degree of reduction of the plastoquinone pool. Surprisingly, the RL to BL shift led to a severe inhibition of growth within the first 48 h which was not observed during the BL to RL shift. Furthermore, during the phase of growth arrest the photosynthetic performance did not change. We propose arguments that the growth arrest could have been caused by the reorganization of intracellular carbon partitioning. PMID:25111046

Light adaptation of the unicellular red alga, Cyanidioschyzon merolae, probed by time-resolved fluorescence spectroscopy.

PubMed

Ueno, Yoshifumi; Aikawa, Shimpei; Kondo, Akihiko; Akimoto, Seiji

2015-08-01

Photosynthetic organisms change the quantity and/or quality of their pigment-protein complexes and the interactions among these complexes in response to light conditions. In the present study, we analyzed light adaptation of the unicellular red alga Cyanidioschyzon merolae, whose pigment composition is similar to that of cyanobacteria because its phycobilisomes (PBS) lack phycoerythrin. C. merolae were grown under different light qualities, and their responses were measured by steady-state absorption, steady-state fluorescence, and picosecond time-resolved fluorescence spectroscopies. Cells were cultivated under four monochromatic light-emitting diodes (blue, green, yellow, and red), and changes in pigment composition and energy transfer were observed. Cells grown under blue and green light increased their relative phycocyanin levels compared with cells cultured under white light. Energy-transfer processes to photosystem I (PSI) were sensitive to yellow and red light. The contribution of direct energy transfer from PBS to PSI increased only under yellow light, while red light induced a reduction in energy transfer from photosystem II to PSI and an increase in energy transfer from light-harvesting chlorophyll protein complex I to PSI. Differences in pigment composition, growth, and energy transfer under different light qualities are discussed.

The PedR transcriptional regulator interacts with thioredoxin to connect photosynthesis with gene expression in cyanobacteria.

PubMed

Horiuchi, Mayumi; Nakamura, Kinu; Kojima, Kouji; Nishiyama, Yoshitaka; Hatakeyama, Wakako; Hisabori, Toru; Hihara, Yukako

2010-10-01

The redox state of the photosynthetic electron transport chain acts as a critical sensing mechanism by regulating the transcription of key genes involved in the acclimation response to a change in the environment. In the present study we show that the small LuxR-type regulator PedR interacts with Trx (thioredoxin) to achieve photosynthetic electron-transport-dependent transcriptional regulation in the cyanobacterium Synechocystis sp. PCC 6803. TrxM, an isoform of Trx, was isolated as an interacting factor of PedR by pull-down assays. In vitro analysis revealed that the intermolecular disulfide bond formed between Cys80 residues of the PedR homodimer was reduced by both TrxM and TrxX. It has been shown previously that, although PedR is active under low-light conditions, it becomes transiently inactivated following a shift to high-light conditions, with a concomitant conformational change [Nakamura and Hihara (2006) J. Biol. Chem. 281, 36758-36766]. In the present study, we found that the conformational change of PedR and the change in the transcript level of its target gene were minimal when mutants of Synechocystis that lack ferredoxin-Trx reductase or NADPH-Trx reductase were exposed to high levels of light. These results indicate that the reduction of PedR by Trx causes transient inactivation of PedR upon the shift of cyanobacterial cells to high-light conditions.

Light-Regulated Transcription of Genes Encoding Peridinin Chlorophyll a Proteins and the Major Intrinsic Light-Harvesting Complex Proteins in the Dinoflagellate Amphidinium carterae Hulburt (Dinophycae)1

PubMed Central

ten Lohuis, Michael R.; Miller, David J.

1998-01-01

In the dinoflagellate Amphidinium carterae, photoadaptation involves changes in the transcription of genes encoding both of the major classes of light-harvesting proteins, the peridinin chlorophyll a proteins (PCPs) and the major a/c-containing intrinsic light-harvesting proteins (LHCs). PCP and LHC transcript levels were increased up to 86- and 6-fold higher, respectively, under low-light conditions relative to cells grown at high illumination. These increases in transcript abundance were accompanied by decreases in the extent of methylation of CpG and CpNpG motifs within or near PCP- and LHC-coding regions. Cytosine methylation levels in A. carterae are therefore nonstatic and may vary with environmental conditions in a manner suggestive of involvement in the regulation of gene expression. However, chemically induced undermethylation was insufficient in activating transcription, because treatment with two methylation inhibitors had no effect on PCP mRNA or protein levels. Regulation of gene activity through changes in DNA methylation has traditionally been assumed to be restricted to higher eukaryotes (deuterostomes and green plants); however, the atypically large genomes of dinoflagellates may have generated the requirement for systems of this type in a relatively “primitive” organism. Dinoflagellates may therefore provide a unique perspective on the evolution of eukaryotic DNA-methylation systems. PMID:9576788

Ribbon synapses compute temporal contrast and encode luminance in retinal rod bipolar cells

PubMed Central

Oesch, Nicholas W.; Diamond, Jeffrey S.

2011-01-01

Contrast is computed throughout the nervous system to encode changing inputs efficiently. The retina encodes luminance and contrast over a wide range of visual conditions and so must adapt its responses to maintain sensitivity and avoid saturation. Here we show how one type of adaptation allows individual synapses to compute contrast and encode luminance in biphasic responses to step changes in light levels. Light-evoked depletion of the readily releasable vesicle pool (RRP) at rod bipolar cell (RBC) ribbon synapses in rat retina limits the dynamic range available to encode transient but not sustained responses, thereby allowing the transient and sustained components of release to compute temporal contrast and encode mean light levels, respectively. A release/replenishment model shows that a single, homogeneous pool of synaptic vesicles is sufficient to generate this behavior and reveals that the dominant mechanism shaping the biphasic contrast/luminance response is the partial depletion of the RRP. PMID:22019730

Evidence of early ultrastructural photoreceptor abnormalities in light-induced retinal degeneration using spectral domain optical coherence tomography.

PubMed

Aziz, Mehak K; Ni, Aiguo; Esserman, Denise A; Chavala, Sai H

2014-07-01

To study spatiotemporal in vivo changes in retinal morphology and quantify thickness of retinal layers in a mouse model of light-induced retinal degeneration using spectral domain optical coherence tomography (SD-OCT). BALB/c mice were exposed to 5000 lux of constant light for 3 h. SD-OCT images were taken 3 h, 24 h, 3 days, 1 week and 1 month after light exposure and were compared with histology at the same time points. SD-OCT images were also taken at 0, 1 and 2 h after light exposure in order to analyse retinal changes at the earliest time points. The thickness of retinal layers was measured using the Bioptigen software InVivoVue Diver. SD-OCT demonstrated progressive outer retinal thinning. 3 h after light exposure, the outer nuclear layer converted from hyporeflective to hyper-reflective. At 24 h, outer retinal bands and nuclear layer demonstrated similar levels of hyper-reflectivity. Significant variations in outer retinal thickness, vitreous opacities and retinal detachments occurred within days of injury. Thinning of the retina was observed at 1 month after injury. It was also determined that outer nuclear layer changes precede photoreceptor segment structure disintegration and the greatest change in segment structure occurs between 1 and 2 h after light exposure. Longitudinal SD-OCT reveals intraretinal changes that cannot be observed by histopathology at early time points in the light injury model. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification.

PubMed

Ow, Yan X; Uthicke, Sven; Collier, Catherine J

2016-01-01

Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m(-2) s(-1)) for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3-) use inhibitors (carbonic anhydrase inhibitor, acetazolamide) and TRIS buffer (pH 8.0). We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion) in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax) and efficiency (α) more in C. serrulata grown under lower light levels (36-60% increase) than for those in high light (4% increase). However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA.

Light Levels Affect Carbon Utilisation in Tropical Seagrass under Ocean Acidification

PubMed Central

2016-01-01

Under future ocean acidification (OA), increased availability of dissolved inorganic carbon (DIC) in seawater may enhance seagrass productivity. However, the ability to utilise additional DIC could be regulated by light availability, often reduced through land runoff. To test this, two tropical seagrass species, Cymodocea serrulata and Halodule uninervis were exposed to two DIC concentrations (447 μatm and 1077 μatm pCO2), and three light treatments (35, 100, 380 μmol m-2 s-1) for two weeks. DIC uptake mechanisms were separately examined by measuring net photosynthetic rates while subjecting C. serrulata and H. uninervis to changes in light and addition of bicarbonate (HCO3-) use inhibitors (carbonic anhydrase inhibitor, acetazolamide) and TRIS buffer (pH 8.0). We observed a strong dependence on energy driven H+-HCO3- co-transport (TRIS, which disrupts H+ extrusion) in C. serrulata under all light levels, indicating greater CO2 dependence in low light. This was confirmed when, after two weeks exposure, DIC enrichment stimulated maximum photosynthetic rates (Pmax) and efficiency (α) more in C. serrulata grown under lower light levels (36–60% increase) than for those in high light (4% increase). However, C. serrulata growth increased with both DIC enrichment and light levels. Growth, NPP and photosynthetic responses in H. uninervis increased with higher light treatments and were independent of DIC availability. Furthermore, H. uninervis was found to be more flexible in HCO3- uptake pathways. Here, light availability influenced productivity responses to DIC enrichment, via both carbon fixation and acquisition processes, highlighting the role of water quality in future responses to OA. PMID:26938454

LED Context Lighting System in Residential Areas

PubMed Central

Im, Kyoung-Mi

2014-01-01

As issues of environment and energy draw keen interest around the globe due to such problems as global warming and the energy crisis, LED with high optical efficiency is brought to the fore as the next generation lighting. In addition, as the national income level gets higher and life expectancy is extended, interest in the enhancement of life quality is increasing. Accordingly, the trend of lightings is changing from mere adjustment of light intensity to system lighting in order to enhance the quality of one's life as well as reduce energy consumption. Thus, this study aims to design LED context lighting system that automatically recognizes the location and acts of a user in residential areas and creates an appropriate lighting environment. The proposed system designed in this study includes three types of processing: first, the creation of a lighting environment index suitable for the user's surroundings and lighting control scenarios and second, it measures and analyzes the optical characteristics that change depending on the dimming control of lighting and applies them to the index. Lastly, it adopts PIR, piezoelectric, and power sensor to grasp the location and acts of the user and create a lighting environment suitable for the current context. PMID:25101325

Absorbance and light scattering of lenses organ cultured with glucose.

PubMed

Alghamdi, Ali Hendi Sahmi; Mohamed, Hasabelrasoul; Sledge, Samiyyah M; Borchman, Douglas

2018-06-06

Purpose/Aim: Diabetes is one of the major factors related to cataract. Our aim was to determine if the attenuation of light through glucose treated lenses was due to light scattering from structural changes or absorbance from metabolic changes. Human and rat lenses were cultured in a medium with and without 55 mM glucose for a period of five days. Absorbance and light scattering were measured using a ultraviolet spectrometer. Aldose reductase and catalase activity, RAGE, and glutathione were measured using classical assays. Almost all of the glucose related attenuation of light through the human lens was due to light scattering from structural changes. Glucose treatment caused three absorbance band to appear at 484, 540 to 644 and 657 nm in both the rat and human lens. The optimum time point for equilibration of human lenses was found to be between 2 and 3 days in organ culture. Glucose caused a more significant effect on the opacity of human lenses compared with rat lenses. Since the levels of glutathione, catalase and aldose reductase were reduced in glucose treated rat lenses compared with untreated lenses, glucose may have caused oxidative stress on the rat lens. The absorbance and light scattering of glucose treated lenses in organ culture were quantitated for the first time which could be important for future studies designed to test the efficacy of agents to ameliorate the opacity. Almost all of the glucose related attenuation of light through the human lens was due to light scattering from structural changes and not absorbance from metabolic changes. Glucose caused a more significant effect on the opacity of human lenses compared with rat lenses. The lens model employed could be used to study the efficacy of agents that potentially ameliorate lens opacity.

Lack of circadian regulation of melatonin rhythms in the sockeye salmon (Oncorhynchus nerka) in vivo and in vitro.

PubMed

Iigo, Masayuki; Azuma, Teruo; Iwata, Munehico

2007-01-01

Melatonin profiles were determined in the plasma in vivo and in the pineal organ in vitro of the sockeye salmon (Oncorhynchus nerka) under various light conditions to test whether they are under circadian regulation. When serial blood samples were taken at 4-h intervals for 3 days via a cannula inserted into the dorsal aorta, plasma melatonin exhibited significant fluctuation under a light-dark cycle, with higher levels during the dark phase than during the light phase. No rhythmic fluctuations persisted under either constant dark or constant light, with constant low and high levels, respectively. Melatonin release from the pineal organ in flow-through culture exhibited a similar pattern in response to the change in light conditions, with high and low release associated with the dark and light phases, respectively. These results indicate that melatonin production in the sockeye salmon is driven by light and darkness but lacks circadian regulation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borer, Elizabeth T.; et al, et al

Human alterations to nutrient cycles1,2 and herbivore communities3–7 are affecting global biodiversity dramatically2. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems8,9. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces tomore » control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.« less

Changes in leaf area, nitrogen content and canopy photosynthesis in soybean exposed to an ozone concentration gradient.

PubMed

Oikawa, Shimpei; Ainsworth, Elizabeth A

2016-08-01

Influences of ozone (O3) on light-saturated rates of photosynthesis in crop leaves have been well documented. To increase our understanding of O3 effects on individual- or stand level productivity, a mechanistic understanding of factors determining canopy photosynthesis is necessary. We used a canopy model to scale photosynthesis from leaf to canopy, and analyzed the importance of canopy structural and leaf ecophysiological characteristics in determining canopy photosynthesis in soybean stands exposed to 9 concentrations of [O3] (37-116 ppb; 9-h mean). Light intensity and N content peaked in upper canopy layers, and sharply decreased through the lower canopy. Plant leaf area decreased with increasing [O3] allowing for greater light intensity to reach lower canopy levels. At the leaf level, light-saturated photosynthesis decreased and dark respiration increased with increasing [O3]. These data were used to calculate daily net canopy photosynthesis (Pc). Pc decreased with increasing [O3] with an average decrease of 10% for an increase in [O3] of 10 ppb, and which was similar to changes in above-ground dry mass production of the stands. Absolute daily net photosynthesis of lower layers was very low and thus the decrease in photosynthesis in the lower canopy caused by elevated [O3] had only minor significance for total canopy photosynthesis. Sensitivity analyses revealed that the decrease in Pc was associated with changes in leaf ecophysiology but not with decrease in leaf area. The soybean stands were very crowded, the leaves were highly mutually shaded, and sufficient light for positive carbon balance did not penetrate to lower canopy leaves, even under elevated [O3]. Copyright © 2016 Elsevier Ltd. All rights reserved.

Adaptation to changes in higher-order stimulus statistics in the salamander retina.

PubMed

Tkačik, Gašper; Ghosh, Anandamohan; Schneidman, Elad; Segev, Ronen

2014-01-01

Adaptation in the retina is thought to optimize the encoding of natural light signals into sequences of spikes sent to the brain. While adaptive changes in retinal processing to the variations of the mean luminance level and second-order stimulus statistics have been documented before, no such measurements have been performed when higher-order moments of the light distribution change. We therefore measured the ganglion cell responses in the tiger salamander retina to controlled changes in the second (contrast), third (skew) and fourth (kurtosis) moments of the light intensity distribution of spatially uniform temporally independent stimuli. The skew and kurtosis of the stimuli were chosen to cover the range observed in natural scenes. We quantified adaptation in ganglion cells by studying linear-nonlinear models that capture well the retinal encoding properties across all stimuli. We found that the encoding properties of retinal ganglion cells change only marginally when higher-order statistics change, compared to the changes observed in response to the variation in contrast. By analyzing optimal coding in LN-type models, we showed that neurons can maintain a high information rate without large dynamic adaptation to changes in skew or kurtosis. This is because, for uncorrelated stimuli, spatio-temporal summation within the receptive field averages away non-gaussian aspects of the light intensity distribution.

[Effect of preparations melatonin and epitalon on the age-related dynamics of thyrotrophic activity of the hypophysis and thyroid gland function in different light regimes].

PubMed

Vinogradova, I A

2009-01-01

The influence of different light regimes (standard lightning--12 hours light/ 12 hours darkness; natural light regime of the North-West of Russia; constant darkness and constant lightning), melatonin and epitalon on the thyrotrophic activity of hypophysis and on the function of thyroid gland was studied. It has been found out that the maximum values of free thyroxin and triiodothyronine in blood were observed in the conditions of constant lightning and the minimal values--in the conditions of light deprivation. In the conditions of natural lightning of Karelia, with orientation on seasonal lightning, the following annual-circadian rhythms were observed: in autumn (period of short lightness duration) the level of free T3 was the lowest; in spring (period of short darkness duration) it was the highest; the inverse relationship was observed by the comparison of free T4 concentration. The lowest values of TSH were observed in old rats kept in constant light and natural light regimes. The concentration of TSH in blood was practically on the same level in the standard regime and in the regime of light deprivation. The age changes of the level of hormones appeared later in rats who received medication, in comparison with the control sets of animals. The use of melatonin and epitalon smoothened the seasonal variations of the level of thyroidal hormones in blood in the lightning conditions of Karelia.

Light at Night and Measures of Alertness and Performance: Implications for Shift Workers.

PubMed

Figueiro, Mariana G; Sahin, Levent; Wood, Brittany; Plitnick, Barbara

2016-01-01

Rotating-shift workers, particularly those working at night, are likely to experience sleepiness, decreased productivity, and impaired safety while on the job. Light at night has been shown to have acute alerting effects, reduce sleepiness, and improve performance. However, light at night can also suppress melatonin and induce circadian disruption, both of which have been linked to increased health risks. Previous studies have shown that long-wavelength (red) light exposure increases objective and subjective measures of alertness at night, without suppressing nocturnal melatonin. This study investigated whether exposure to red light at night would not only increase measures of alertness but also improve performance. It was hypothesized that exposure to both red (630 nm) and white (2,568 K) lights would improve performance but that only white light would significantly affect melatonin levels. Seventeen individuals participated in a 3-week, within-subjects, nighttime laboratory study. Compared to remaining in dim light, participants had significantly faster reaction times in the GO/NOGO test after exposure to both red light and white light. Compared to dim light exposure, power in the alpha and alpha-theta regions was significantly decreased after exposure to red light. Melatonin levels were significantly suppressed by white light only. Results show that not only can red light improve measures of alertness, but it can also improve certain types of performance at night without affecting melatonin levels. These findings could have significant practical applications for nurses; red light could help nurses working rotating shifts maintain nighttime alertness, without suppressing melatonin or changing their circadian phase. © The Author(s) 2015.

Modeling future scenarios of light attenuation and potential seagrass success in a eutrophic estuary

USGS Publications Warehouse

del Barrio, Pilar; Ganju, Neil K.; Aretxabaleta, Alfredo L.; Hayn, Melanie; García, Andrés; Howarth, Robert W.

2014-01-01

Estuarine eutrophication has led to numerous ecological changes, including loss of seagrass beds. One potential cause of these losses is a reduction in light availability due to increased attenuation by phytoplankton. Future sea level rise will also tend to reduce light penetration and modify seagrass habitat. In the present study, we integrate a spectral irradiance model into a biogeochemical model coupled to the Regional Ocean Model System (ROMS). It is linked to a bio-optical seagrass model to assess potential seagrass habitat in a eutrophic estuary under future nitrate loading and sea-level rise scenarios. The model was applied to West Falmouth Harbor, a shallow estuary located on Cape Cod (Massachusetts) where nitrate from groundwater has led to eutrophication and seagrass loss in landward portions of the estuary. Measurements of chlorophyll, turbidity, light attenuation, and seagrass coverage were used to assess the model accuracy. Mean chlorophyll based on uncalibrated in-situ fluorometry varied from 28 μg L−1 at the landward-most site to 6.5 μg L−1 at the seaward site, while light attenuation ranged from 0.86 to 0.45 m-1. The model reproduced the spatial variability in chlorophyll and light attenuation with RMS errors of 3.72 μg L−1 and 0.07 m-1 respectively. Scenarios of future nitrate reduction and sea-level rise suggest an improvement in light climate in the landward basin with a 75% reduction in nitrate loading. This coupled model may be useful to assess habitat availability changes due to eutrophication and sediment resuspension and fully considers spatial variability on the tidal timescale.

Light-Regulated Thyroid Hormone Signaling Is Required for Rod Photoreceptor Development in the Mouse Retina.

PubMed

Sawant, Onkar; Horton, Amanda M; Shukla, Meenal; Rayborn, Mary E; Peachey, Neal S; Hollyfield, Joe G; Rao, Sujata

2015-12-01

Ambient light is both a stimulus for visual function and a regulator of photoreceptor physiology. However, it is not known if light can regulate any aspect of photoreceptor development. The purpose of this study was to investigate whether ambient light is required for the development of mouse rod photoreceptors. Newborn mouse pups (C57BL/6) were reared in either cyclic light (LD) or constant dark (DD). Pups were collected at postnatal day (P)5, P10, P17, or P24. We performed retinal morphometric and cell death analysis at P5, P10, and P17. Rhodopsin expression was assessed using immunofluorescence, Western blot, and quantitative RT-PCR analysis. Electroretinograms were performed at P17 and P24. Radioimmunoassay and ELISA were used to follow changes in thyroid hormone levels in the serum and vitreous. In the DD pups, the outer nuclear layer was significantly thinner at P10 and there were higher numbers of apoptotic cells at P5 compared to the LD pups. Rhodopsin expression was lower at P10 and P17 in DD pups. Electroretinogram a-waves were reduced in amplitude at P17 in the DD pups. The DD animals had lower levels of circulating thyroid hormones at P10. Light-mediated changes in thyroid hormones occur as early as P5, as we detected lower levels of total triiodothyronine in the vitreous from the DD animals. Drug-induced developmental hypothyroidism resulted in lower rhodopsin expression at P10. Our data demonstrate that light exposure during postnatal development is required for rod photoreceptor development and that this effect could be mediated by thyroid hormone signaling.

Giant Clams and Rising CO2: Light May Ameliorate Effects of Ocean Acidification on a Solar-Powered Animal

PubMed Central

Watson, Sue-Ann

2015-01-01

Global climate change and ocean acidification pose a serious threat to marine life. Marine invertebrates are particularly susceptible to ocean acidification, especially highly calcareous taxa such as molluscs, echinoderms and corals. The largest of all bivalve molluscs, giant clams, are already threatened by a variety of local pressures, including overharvesting, and are in decline worldwide. Several giant clam species are listed as ‘Vulnerable’ on the IUCN Red List of Threatened Species and now climate change and ocean acidification pose an additional threat to their conservation. Unlike most other molluscs, giant clams are ‘solar-powered’ animals containing photosynthetic algal symbionts suggesting that light could influence the effects of ocean acidification on these vulnerable animals. In this study, juvenile fluted giant clams Tridacna squamosa were exposed to three levels of carbon dioxide (CO2) (control ~400, mid ~650 and high ~950 μatm) and light (photosynthetically active radiation 35, 65 and 304 μmol photons m-2 s-1). Elevated CO2 projected for the end of this century (~650 and ~950 μatm) reduced giant clam survival and growth at mid-light levels. However, effects of CO2 on survival were absent at high-light, with 100% survival across all CO2 levels. Effects of CO2 on growth of surviving clams were lessened, but not removed, at high-light levels. Shell growth and total animal mass gain were still reduced at high-CO2. This study demonstrates the potential for light to alleviate effects of ocean acidification on survival and growth in a threatened calcareous marine invertebrate. Managing water quality (e.g. turbidity and sedimentation) in coastal areas to maintain water clarity may help ameliorate some negative effects of ocean acidification on giant clams and potentially other solar-powered calcifiers, such as hard corals. PMID:26083404

Giant Clams and Rising CO2: Light May Ameliorate Effects of Ocean Acidification on a Solar-Powered Animal.

PubMed

Watson, Sue-Ann

2015-01-01

Global climate change and ocean acidification pose a serious threat to marine life. Marine invertebrates are particularly susceptible to ocean acidification, especially highly calcareous taxa such as molluscs, echinoderms and corals. The largest of all bivalve molluscs, giant clams, are already threatened by a variety of local pressures, including overharvesting, and are in decline worldwide. Several giant clam species are listed as 'Vulnerable' on the IUCN Red List of Threatened Species and now climate change and ocean acidification pose an additional threat to their conservation. Unlike most other molluscs, giant clams are 'solar-powered' animals containing photosynthetic algal symbionts suggesting that light could influence the effects of ocean acidification on these vulnerable animals. In this study, juvenile fluted giant clams Tridacna squamosa were exposed to three levels of carbon dioxide (CO2) (control ~400, mid ~650 and high ~950 μatm) and light (photosynthetically active radiation 35, 65 and 304 μmol photons m-2 s-1). Elevated CO2 projected for the end of this century (~650 and ~950 μatm) reduced giant clam survival and growth at mid-light levels. However, effects of CO2 on survival were absent at high-light, with 100% survival across all CO2 levels. Effects of CO2 on growth of surviving clams were lessened, but not removed, at high-light levels. Shell growth and total animal mass gain were still reduced at high-CO2. This study demonstrates the potential for light to alleviate effects of ocean acidification on survival and growth in a threatened calcareous marine invertebrate. Managing water quality (e.g. turbidity and sedimentation) in coastal areas to maintain water clarity may help ameliorate some negative effects of ocean acidification on giant clams and potentially other solar-powered calcifiers, such as hard corals.

A Study of Gibberellin Homeostasis and Cryptochrome-Mediated Blue Light Inhibition of Hypocotyl Elongation1[W][OA

PubMed Central

Zhao, Xiaoying; Yu, Xuhong; Foo, Eloise; Symons, Gregory M.; Lopez, Javier; Bendehakkalu, Krishnaprasad T.; Xiang, Jing; Weller, James L.; Liu, Xuanming; Reid, James B.; Lin, Chentao

2007-01-01

Cryptochromes mediate blue light-dependent photomorphogenic responses, such as inhibition of hypocotyl elongation. To investigate the underlying mechanism, we analyzed a genetic suppressor, scc7-D (suppressors of cry1cry2), which suppressed the long-hypocotyl phenotype of the cry1cry2 (cryptochrome1/cryptochrome2) mutant in a light-dependent but wavelength-independent manner. scc7-D is a gain-of-expression allele of the GA2ox8 gene encoding a gibberellin (GA)-inactivating enzyme, GA 2-oxidase. Although scc7-D is hypersensitive to light, transgenic seedlings expressing GA2ox at a level higher than scc7-D showed a constitutive photomorphogenic phenotype, confirming a general role of GA2ox and GA in the suppression of hypocotyl elongation. Prompted by this result, we investigated blue light regulation of mRNA expression of the GA metabolic and catabolic genes. We demonstrated that cryptochromes are required for the blue light regulation of GA2ox1, GA20ox1, and GA3ox1 expression in transient induction, continuous illumination, and photoperiodic conditions. The kinetics of cryptochrome induction of GA2ox1 expression and cryptochrome suppression of GA20ox1 or GA3ox1 expression correlate with the cryptochrome-dependent transient reduction of GA4 in etiolated wild-type seedlings exposed to blue light. Therefore we propose that in deetiolating seedlings, cryptochromes mediate blue light regulation of GA catabolic/metabolic genes, which affect GA levels and hypocotyl elongation. Surprisingly, no significant change in the GA4 content was detected in the whole shoot samples of the wild-type or cry1cry2 seedlings grown in the dark or continuous blue light, suggesting that cryptochromes may also regulate GA responsiveness and/or trigger cell- or tissue-specific changes of the level of bioactive GAs. PMID:17644628

Exposure of tropical ecosystems to artificial light at night: Brazil as a case study

PubMed Central

Bennie, Jon; Mantovani, Waldir; Gaston, Kevin J.

2017-01-01

Artificial nighttime lighting from streetlights and other sources has a broad range of biological effects. Understanding the spatial and temporal levels and patterns of this lighting is a key step in determining the severity of adverse effects on different ecosystems, vegetation, and habitat types. Few such analyses have been conducted, particularly for regions with high biodiversity, including the tropics. We used an intercalibrated version of the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS) images of stable nighttime lights to determine what proportion of original and current Brazilian vegetation types are experiencing measurable levels of artificial light and how this has changed in recent years. The percentage area affected by both detectable light and increases in brightness ranged between 0 and 35% for native vegetation types, and between 0 and 25% for current vegetation (i.e. including agriculture). The most heavily affected areas encompassed terrestrial coastal vegetation types (restingas and mangroves), Semideciduous Seasonal Forest, and Mixed Ombrophilous Forest. The existing small remnants of Lowland Deciduous and Semideciduous Seasonal Forests and of Campinarana had the lowest exposure levels to artificial light. Light pollution has not often been investigated in developing countries but our data show that it is an environmental concern. PMID:28178352

Bright lights, big city: influences of ecological light pollution on reciprocal stream-riparian invertebrate fluxes.

PubMed

Meyer, Lars A; Sullivan, S Mazeika P

2013-09-01

Cities produce considerable ecological light pollution (ELP), yet the effects of artificial night lighting on biological communities and ecosystem function have not been fully explored. From June 2010 to June 2011, we surveyed aquatic emergent insects, riparian arthropods entering the water, and riparian spiders of the family Tetragnathidae at nine stream reaches representing common ambient ELP levels of Columbus, Ohio, USA, streams (low, 0.1-0.5 lux; moderate, 0.6-2.0 lux; high, 2.1-4.0 lux). In August 2011, we experimentally increased light levels at the low- and moderate-treatment reaches to 10-12 lux to represent urban streams exposed to extremely high levels of ELP. Although season exerted the dominant influence on invertebrate fluxes over the course of the year, when analyzed by season, we found that light strongly influenced multiple invertebrate responses. The experimental light addition resulted in a 44% decrease in tetragnathid spider density (P = 0.035), decreases of 16% in family richness (P = 0.040) and 76% in mean body size (P = 0.022) of aquatic emergent insects, and a 309% increase in mean body size of terrestrial arthropods (P = 0.015). Our results provide evidence that artificial light sources can alter community structure and ecosystem function in streams via changes in reciprocal aquatic-terrestrial fluxes of invertebrates.

Expression of Leaf Nitrate Reductase Genes from Tomato and Tobacco in Relation to Light-Dark Regimes and Nitrate Supply

PubMed Central

Galangau, Fabienne; Daniel-Vedele, Françoise; Moureaux, Thérèse; Dorbe, Marie-France; Leydecker, Marie-Thérèse; Caboche, Michel

1988-01-01

The influence of light-dark cycles and nitrate supply on nitrate reductase (NR) mRNA levels was studied in two plant species, tobacco (Nicotiana tabacum) and tomato (Lycopersicon esculentum) using specific NR DNA probes. In the same series of experiments, changes in the levels of NR protein (NRP) by enzyme-linked immunosorbent assay and changes in the level of NADH-nitrate reductase activity (NRA) were also followed. During a light-dark cycle, it was found that in both tomato and tobacco, NR mRNA accumulation increased rapidly during the dark period and reached a maximum at the beginning of the day, while NRP reached a peak 2 and 4 hours after mRNA peaked, for tomato and tobacco, respectively. At the end of the day, the amount of mRNA was decreased by a factor of at least 100 compared to sunrise in both species. These results demonstrate that light is involved, although probably not directly, in the regulation of the NR gene expression at the mRNA level. The peak of NRA in tobacco coincided with the peak in NR mRNA accumulation (i.e. sunrise), whereas in tomato the peak of NRA was approximately 5 to 6 hours after sunrise. There is no obvious correlation between NRP and NRA levels during the day. In nitrogen starvation experiments, a rapid decrease of NRP and NRA was detected, while NR mRNA levels were not significantly altered. Upon nitrate replenishment, nitrogen-starved plants accumulated NR mRNA rapidly. These results suggest that the availability of nitrogen affects the expression of NR activity at the transcriptional as well as at the post-transcriptional levels. Images Fig. 3 Fig. 5 Fig. 6 PMID:16666313

Effects of 810 nm laser on mouse primary cortical neurons

NASA Astrophysics Data System (ADS)

Kharkwal, Gitika B.; Sharma, Sulbha K.; Huang, Ying-Ying; De Taboada, Luis; McCarthy, Thomas; Hamblin, Michael R.

2011-03-01

In the past four decades numerous studies have reported the efficacy of low level light (laser) therapy (LLLT) as a treatment for diverse diseases and injuries. Recent studies have shown that LLLT can biomodulate processes in the central nervous system and has been extensively studied as a stroke treatment. However there is still a lack of knowledge on the effects of LLLT at the cellular level in neurons. The present study aimed to study the effect of 810 nm laser on several cellular processes in primary cortical neurons cultured from mouse embryonic brains. Neurons were irradiated with light dose of 0.03, 0.3, 3, 10 and 30 J/cm2 and intracellular levels of reactive oxygen species, nitric oxide and calcium were measured. The changes in mitochondrial function in response to light were studied in terms of adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP). Light induced a significant increase in calcium, ATP and MMP at lower fluences and a decrease at higher fluence. ROS was induced significantly by light at all light doses. Nitric oxide levels also showed an increase on treatment with light. The results of the present study suggest that LLLT at lower fluences is capable of inducing mediators of cell signaling process which in turn may be responsible for the biomodulatory effects of the low level laser. At higher fluences beneficial mediators are reduced but potentially harmful mediators are increased thus offering an explanation for the biphasic dose response.

Photoreception and signal transduction in corals: proteomic and behavioral evidence for cytoplasmic calcium as a mediator of light responsivity.

PubMed

Hilton, J Daniel; Brady, Aisling K; Spaho, Skender A; Vize, Peter D

2012-12-01

Little is known about how corals sense and respond to light. In this report the proteome of coral is explored using 2D protein electrophoresis in two species, Montastraea cavernosa and Acropora millepora. Multiple protein species have major shifts in abundance in both species when sampled in daylight compared to corals sampled late in the night. These changes were observed both in larvae lacking zooxanthellae and in adult tissue containing zooxanthellae, including both Pacific and Caribbean corals. When larvae kept in the dark were treated with either thapsigargin or ionomycin, compounds that raise the level of cytoplasmic calcium, the night pattern of proteins shifted to the day pattern. This implies that photoreceptors responding to light elevate calcium levels and that calcium acts as the second messenger relaying light responses in corals. Corals spawn at night, and spawning can be delayed by exposure to light or pushed forward by early artificial sunsets. In a series of behavioral experiments, treatment of corals with ionomycin or thapsigargin was found to delay broadcast spawning in M. franksi, demonstrating that pharmacologically altering cytoplasmic calcium levels generates the same response as light exposure. Together these results show that the photo-responsive cells of corals detect and respond to light by altering cytoplasmic calcium levels, similarly to the transduction pathways in complex invertebrate eyes. The primacy of cytoplasmic calcium levels in light responsivity has broad implications for coral reproduction, including predicting how different species spawn at different times after sunset and how reproductive isolation is achieved during coral speciation.

Daytime exposure to bright light, as compared to dim light, decreases sleepiness and improves psychomotor vigilance performance.

PubMed

Phipps-Nelson, Jo; Redman, Jennifer R; Dijk, Derk-Jan; Rajaratnam, Shantha M W

2003-09-01

This study examined the effects of bright light exposure, as compared to dim light, on daytime subjective sleepiness, incidences of slow eye movements (SEMs), and psychomotor vigilance task (PVT) performance following 2 nights of sleep restriction. The study had a mixed factorial design with 2 independent variables: light condition (bright light, 1,000 lux; dim light, < 5 lux) and time of day. The dependent variables were subjective sleepiness, PVT performance, incidences of SEMs, and salivary melatonin levels. Sleep research laboratory at Monash University. Sixteen healthy adults (10 women and 6 men) aged 18 to 35 years (mean age 25 years, 3 months). Following 2 nights of sleep restriction (5 hours each night), participants were exposed to modified constant routine conditions. Eight participants were exposed to bright light from noon until 5:00 pm. Outside the bright light exposure period (9:00 am to noon, 5:00 pm to 9:00 pm) light levels were maintained at less than 5 lux. A second group of 8 participants served as controls for the bright light exposure and were exposed to dim light throughout the entire protocol. Bright light exposure reduced subjective sleepiness, decreased SEMs, and improved PVT performance compared to dim light. Bright lights had no effect on salivary melatonin. A significant positive correlation between PVT reaction times and subjective sleepiness was observed for both groups. Changes in SEMs did not correlate significantly with either subjective sleepiness or PVT performance. Daytime bright light exposure can reduce the impact of sleep loss on sleepiness levels and performance, as compared to dim light. These effects appear to be mediated by mechanisms that are separate from melatonin suppression. The results may assist in the development of treatments for daytime sleepiness.

Metabolomic Responses of Arabidopsis Suspension Cells to Bicarbonate under Light and Dark Conditions

PubMed Central

Misra, Biswapriya B.; Yin, Zepeng; Geng, Sisi; de Armas, Evaldo; Chen, Sixue

2016-01-01

Global CO2 level presently recorded at 400 ppm is expected to reach 550 ppm in 2050, an increment likely to impact plant growth and productivity. Using targeted LC-MS and GC-MS platforms we quantified 229 and 29 metabolites, respectively in a time-course study to reveal short-term responses to different concentrations (1, 3, and 10 mM) of bicarbonate (HCO3−) under light and dark conditions. Results indicate that HCO3− treatment responsive metabolomic changes depend on the HCO3− concentration, time of treatment, and light/dark. Interestingly, 3 mM HCO3− concentration treatment induced more significantly changed metabolites than either lower or higher concentrations used. Flavonoid biosynthesis and glutathione metabolism were common to both light and dark-mediated responses in addition to showing concentration-dependent changes. Our metabolomics results provide insights into short-term plant cellular responses to elevated HCO3− concentrations as a result of ambient increases in CO2 under light and dark. PMID:27762345

Genome-Wide Characterization of Light-Regulated Genes in Neurospora crassa

PubMed Central

Wu, Cheng; Yang, Fei; Smith, Kristina M.; Peterson, Matthew; Dekhang, Rigzin; Zhang, Ying; Zucker, Jeremy; Bredeweg, Erin L.; Mallappa, Chandrashekara; Zhou, Xiaoying; Lyubetskaya, Anna; Townsend, Jeffrey P.; Galagan, James E.; Freitag, Michael; Dunlap, Jay C.; Bell-Pedersen, Deborah; Sachs, Matthew S.

2014-01-01

The filamentous fungus Neurospora crassa responds to light in complex ways. To thoroughly study the transcriptional response of this organism to light, RNA-seq was used to analyze capped and polyadenylated mRNA prepared from mycelium grown for 24 hr in the dark and then exposed to light for 0 (control) 15, 60, 120, and 240 min. More than three-quarters of all defined protein coding genes (79%) were expressed in these cells. The increased sensitivity of RNA-seq compared with previous microarray studies revealed that the RNA levels for 31% of expressed genes were affected two-fold or more by exposure to light. Additionally, a large class of mRNAs, enriched for transcripts specifying products involved in rRNA metabolism, showed decreased expression in response to light, indicating a heretofore undocumented effect of light on this pathway. Based on measured changes in mRNA levels, light generally increases cellular metabolism and at the same time causes significant oxidative stress to the organism. To deal with this stress, protective photopigments are made, antioxidants are produced, and genes involved in ribosome biogenesis are transiently repressed. PMID:25053707

A computational model of pupil dilation

NASA Astrophysics Data System (ADS)

Johansson, Birger; Balkenius, Christian

2018-01-01

We present a system-level connectionist model of pupil control that includes brain regions believed to influence the size of the pupil. It includes parts of the sympathetic and parasympathetic nervous system together with the hypothalamus, amygdala, locus coeruleus, and cerebellum. Computer simulations show that the model is able to reproduce a number of important aspects of how the pupil reacts to different stimuli: (1) It reproduces the characteristic shape and latency of the light-reflex. (2) It elicits pupil dilation as a response to novel stimuli. (3) It produces pupil dilation when shown emotionally charged stimuli, and can be trained to respond to initially neutral stimuli through classical conditioning. (4) The model can learn to expect light changes for particular stimuli, such as images of the sun, and produces a "light-response" to such stimuli even when there is no change in light intensity. (5) It also reproduces the fear-inhibited light reflex effect where reactions to light increase is weaker after presentation of a conditioned stimulus that predicts punishment.

Effect of green light spectra on the reduction of retinal damage and stress in goldfish, Carassius auratus.

PubMed

Song, Jin Ah; Kim, Na Na; Choi, Young Jae; Choi, Cheol Young

2016-07-22

We investigated the effect of light spectra on retinal damage and stress in goldfish using green (530 nm) and red (620 nm) light emitting diodes (LEDs) at three intensities each (0.5, 1.0, and 1.5 W/m(2)). We measured the change in the levels of plasma cortisol and H2O2 and expression and levels of caspase-3. The apoptotic response of green and red LED spectra was assessed using the terminal transferase dUTP nick end labeling (TUNEL) assay. Stress indicator (cortisol and H2O2) and apoptosis-related genes (caspase-3) decreased in green light, but increased in red light with higher light intensities over time. The TUNEL assay revealed that more apoptotic cells were detected in outer nuclear layers after exposure to red LED over time with the increase in light intensity, than the other spectra. These results indicate that green light efficiently reduces retinal damage and stress, whereas red light induces it. Therefore, red light-induced retina damage may induce apoptosis in goldfish retina. Copyright © 2016 Elsevier Inc. All rights reserved.

Faraday effect on stimulated Raman scattering in the linear region

NASA Astrophysics Data System (ADS)

Liu, Z. J.; Li, B.; Xiang, J.; Cao, L. H.; Zheng, C. Y.; Hao, L.

2018-04-01

The paper presents the effect of Faraday rotation on stimulated Raman scattering (SRS). When light propagates along the magnetic field upon plasma, Faraday rotation occurs. The rotation angle can be expressed as {{d}}θ /{{d}}{s}=2.93× {10}-4B\\tfrac{{n}e/{n}c}{\\sqrt{1-{n}e/{n}c}} {cm}}-1 approximately, where θ is the rotation angle and s is distance, n e is the electron density, n c is the critical density and B is magnetic field in unit of Gauss. Both the incident light and Raman light have Faraday effects. The angle between the polarization directions of incident light and Raman light changes with position. The driven force of electron plasma wave also reduces, and then SRS scattering level is reduced. Faraday rotation effect can increase the laser intensity threshold of Raman scattering, even if the magnetic field strength is small. The circularly polarized light incident case is also compared with that of the linearly polarized light incident. The Raman scattering level of linearly polarized light is much smaller than that of circularly polarized light in the magnetized plasma. The difference between linearly and circularly polarized lights is also discussed.

Relationship between the change of ethological status and concentration of certain cytokines in blood in experimental desynchronosis under led lighting.

PubMed

Osikov, M V; Ogneva, O I

2016-01-01

Changing the natural rhythm of day and night leads to the development of DS, disruption of coordinated muscular activity, adequate behavioral activity, a decrease of attention in the performance of night work by experts in various fields. Changes ethological status may potentiate or weaken the changes in the indices of immune status, contribute to the formation of allostatic load at desynchronosis. To investigate the relationship between changes ethological status and concentration of certain cytokines in peripheral blood in experimental desynchronosis under LED lighting. The study was performed on 158 adult guinea pigs, which were randomly assigned into 2 groups: 1 group- animals in the conditions of standard fixed (12 h light / 12 h dark) LED lighting (SFSDO); 2 group- animals with jet lag in terms of LED lighting (DESSDO). Light desynchronosis created by keeping animals at clock coverage for 30 days. Behavioral activity was studied in the test «open field» cognitive function was assessed using aqueous «labyrinth» Morris. By ELISA was determined on the apparatus in the peripheral blood concentration of interleukin - 4 (IL-4), interferon-gamma (IFN-g), melatonin, cortisol via specific for guinea pig test systems. It was found that in animals of DS in terms of LED lighting in the dynamics of 10-30 days of observation show signs of anxiety, depression orienting-exploratory behavior, reduce the long-term memory and learning ability, spatial orientation disorders. It found that when a jet lag LED lighting conditions for 10 days, 20 days and 30 days in peripheral blood melatonin concentration decreases, the concentration of cortisol rises. In peripheral blood decreased IL-4 concentrations of 20 and 30 days, reducing the concentration of IFN-g at 30 days. Based on the results of correlation analysis, ethological change status and progress of cognitive function with a decrease in the blood concentration of IL-4 and IFN-g, the concentration of melatonin increase cortisol levels. The results indicate that in experimental conditions in desynchronosis LED lighting changes ethological status are associated with the progression of immune status changes.

The short-term response of Arabidopsis thaliana (C3) and Zea mays (C4) chloroplasts to red and far red light.

PubMed

Zienkiewicz, Maksymilian; Drożak, Anna; Wasilewska, Wioleta; Bacławska, Ilona; Przedpełska-Wąsowicz, Ewa; Romanowska, Elżbieta

2015-12-01

Light quality has various effects on photochemistry and protein phosphorylation in Zea mays and Arabidopsis thaliana thylakoids due to different degrees of light penetration across leaves and redox status in chloroplasts. The effect of the spectral quality of light (red, R and far red, FR) on the function of thylakoid proteins in Zea mays and Arabidopsis thaliana was investigated. It was concluded that red light stimulates PSII activity in A. thaliana thylakoids and in maize bundle sheath (BS) thylakoids, but not in mesophyll (M) thylakoids. The light quality did not change PSI activity in M thylakoids of maize. FR used after a white light period increased PSI activity significantly in maize BS and only slightly in A. thaliana thylakoids. As shown by blue native (BN)-PAGE followed by SDS-PAGE, proteins were differently phosphorylated in the thylakoids, indicating their different functions. FR light increased dephosphorylation of LHCII proteins in A. thaliana thylakoids, whereas in maize, dephosphorylation did not occur at all. The rate of phosphorylation was higher in maize BS than in M thylakoids. D1 protein phosphorylation increased in maize and decreased in A. thaliana upon irradiation with both R and growth light (white light, W). Light variations did not change the level of proteins in thylakoids. Our data strongly suggest that response to light quality is a species-dependent phenomenon. We concluded that the maize chloroplasts were differently stimulated, probably due to different degrees of light penetration across the leaf and thereby the redox status in the chloroplasts. These acclimation changes induced by light quality are important in the regulation of chloroplast membrane flexibility and thus its function.

Leaf-level gas-exchange uniformity and photosynthetic capacity among loblolly pine (Pinus taeda L.) genotypes of contrasting inherent genetic variation

Treesearch

Michael J. Aspinwall; John S. King; Steven E. McKeand; Jean-Christophe Domec

2011-01-01

Variation in leaf-level gas exchange among widely planted genetically improved loblolly pine (Pinus taeda L.) genotypes could impact stand-level water use, carbon assimilation, biomass production, C allocation, ecosystem sustainability and biogeochemical cycling under changing environmental conditions. We examined uniformity in leaf-level light-saturated photosynthesis...

Fiber optic level sensor for cryogens

NASA Technical Reports Server (NTRS)

Sharma, M.

1981-01-01

Sensor is useful in cryogenic environments where liquids of very low index of refraction are encountered. It is "yes/no" indication of whether liquid is in contact with sensor. Sharp bends in fiber alter distribution of light among propagation modes. This amplifies change in light output observed when sensor contacts liquid, without requiring long fiber that would increse insertion loss.

Red light-regulated growth. I. Changes in the abundance of indoleacetic acid and a 22-kilodalton auxin-binding protein in the maize mesocotyl

NASA Technical Reports Server (NTRS)

Jones, A. M.; Cochran, D. S.; Lamerson, P. M.; Evans, M. L.; Cohen, J. D.

1991-01-01

We examined the changes in the levels of indoleacetic acid (IAA), IAA esters, and a 22-kilodalton subunit auxin-binding protein (ABP1) in apical mesocotyl tissue of maize (Zea mays L.) during continuous red light (R) irradiation. These changes were compared with the kinetics of R-induced growth inhibition in the same tissue. Upon the onset of continuous irradiation, growth decreased in a continuous manner following a brief lag period. The decrease in growth continued for 5 hours, then remained constant at 25% of the dark rate. The abundance of ABP1 and the level of free IAA both decreased in the mesocotyl. Only the kinetics of the decrease in IAA within the apical mesocotyl correlated with the initial change in growth, although growth continued to decrease even after IAA content reached its final level, 50% of the dark control. This decrease in IAA within the mesocotyl probably occurs primarily by a change in its transport within the shoot since auxin applied as a pulse move basipetally in R-irradiated tissue at the same rate but with half the area as dark control tissue. In situ localization of auxin in etiolated maize shoots revealed that R-irradiated shoots contained less auxin in the epidermis than the dark controls. Irradiated mesocotyl grew 50% less than the dark controls even when incubated in an optimal level of auxin. However, irradiated and dark tissue contained essentially the same amount of radioactivity after incubation in [14C]IAA indicating that the light treatment does not affect the uptake into the tissue through the cut end, although it is possible that a small subset of cells within the mesocotyl is affected. These observations support the hypothesis that R causes a decrease in the level of auxin in epidermal cells of the mesocotyl, consequently constraining the growth of the entire mesocotyl.

The pupillary light responses of animals; a review of their distribution, dynamics, mechanisms and functions.

PubMed

Douglas, Ronald H

2018-05-01

The timecourse and extent of changes in pupil area in response to light are reviewed in all classes of vertebrate and cephalopods. Although the speed and extent of these responses vary, most species, except the majority of teleost fish, show extensive changes in pupil area related to light exposure. The neuromuscular pathways underlying light-evoked pupil constriction are described and found to be relatively conserved, although the precise autonomic mechanisms differ somewhat between species. In mammals, illumination of only one eye is known to cause constriction in the unilluminated pupil. Such consensual responses occur widely in other animals too, and their function and relation to decussation of the visual pathway is considered. Intrinsic photosensitivity of the iris muscles has long been known in amphibia, but is in fact widespread in other animals. The functions of changes in pupil area are considered. In the majority of species, changes in pupil area serve to balance the conflicting demands of high spatial acuity and increased sensitivity in different light levels. In the few teleosts in which pupil movements occur they do not serve a visual function but play a role in camouflaging the eye of bottom-dwelling species. The occurrence and functions of the light-independent changes in pupil size displayed by many animals are also considered. Finally, the significance of the variations in pupil shape, ranging from circular to various orientations of slits, ovals, and other shapes, is discussed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Using the Transient Response of WO₃ Nanoneedles under Pulsed UV Light in the Detection of NH₃ and NO₂.

PubMed

Gonzalez, Oriol; Welearegay, Tesfalem G; Vilanova, Xavier; Llobet, Eduard

2018-04-26

Here we report on the use of pulsed UV light for activating the gas sensing response of metal oxides. Under pulsed UV light, the resistance of metal oxides presents a ripple due to light-induced transient adsorption and desorption phenomena. This methodology has been applied to tungsten oxide nanoneedle gas sensors operated either at room temperature or under mild heating (50 °C or 100 °C). It has been found that by analyzing the rate of resistance change caused by pulsed UV light, a fast determination of gas concentration is achieved (ten-fold improvement in response time). The technique is useful for detecting both oxidizing (NO₂) and reducing (NH₃) gases, even in the presence of different levels of ambient humidity. Room temperature operated sensors under pulsed UV light show good response towards ammonia and nitrogen dioxide at low power consumption levels. Increasing their operating temperature to 50 °C or 100 °C has the effect of further increasing sensitivity.

VARIATION IN THE ABUNDANCE OF SYNECHOCOCCUS SP. CC9311 NARB MRNA RELATIVE TO CHANGES IN LIGHT, NITROGEN GROWTH CONDITIONS AND NITRATE ASSIMILATION(1).

PubMed

Paerl, Ryan W; Tozzi, Sasha; Kolber, Zbigniew S; Zehr, Jonathan P

2012-08-01

Synechococcus- and Prochlorococcus-specific narB genes that encode for an assimilatory nitrate reductase are found in coastal to open-ocean waters. However, it remains uncertain if these picocyanobacteria assimilate nitrate in situ. This unknown can potentially be addressed by examining narB mRNA from the environment, but this requires a better understanding of the influence of environmental factors on narB gene transcription. In laboratory experiments with Synechococcus sp. CC9311 cultures exposed to diel light fluctuations and grown on nitrate or ammonium, there was periodic change in narB transcript abundance. This periodicity was broken in cultures subjected to a doubling of irradiance (40-80 μmol photons · m(-2)  · s(-1) ) during the mid-light period. Therefore, the irradiance level, not circadian rhythm, was the dominant factor controlling narB transcription. In nitrate-grown cultures, diel change in narB transcript abundance and nitrate assimilation rate did not correlate; suggesting narB mRNA levels better indicate nitrate assimilation activity than assimilation rate. Growth history also affected narB transcription, as changes in narB mRNA levels in nitrogen-deprived CC9311 cultures following nitrate amendment were distinct from cultures grown solely on nitrate. Environmental sampling for narB transcripts should consider time, irradiance, and the growth status of cells to ecologically interpret narB transcript abundances. © 2012 Phycological Society of America.

The promoter activities of sucrose phosphate synthase genes in rice, OsSPS1 and OsSPS11, are controlled by light and circadian clock, but not by sucrose.

PubMed

Yonekura, Madoka; Aoki, Naohiro; Hirose, Tatsuro; Onai, Kiyoshi; Ishiura, Masahiro; Okamura, Masaki; Ohsugi, Ryu; Ohto, Chikara

2013-01-01

Although sucrose plays a role in sugar sensing and its signaling pathway, little is known about the regulatory mechanisms of the expressions of plant sucrose-related genes. Our previous study on the expression of the sucrose phosphate synthase gene family in rice (OsSPSs) suggested the involvement of sucrose sensing and/or circadian rhythm in the transcriptional regulation of OsSPS. To examine whether the promoters of OsSPSs can be controlled by sugars and circadian clock, we produced transgenic rice plants harboring a promoter-luciferase construct for OsSPS1 or OsSPS11 and analyzed the changes in the promoter activities by monitoring bioluminescence from intact transgenic plants in real-time. Transgenic plants fed sucrose, glucose, or mannitol under continuous light conditions showed no changes in bioluminescence intensity; meanwhile, the addition of sucrose increased the concentration of sucrose in the plants, and the mRNA levels of OsSPS remained constant. These results suggest that these OsSPS promoters may not be regulated by sucrose levels in the tissues. Next, we investigated the changes in the promoter activities under 12-h light/12-h dark cycles and continuous light conditions. Under the light-dark cycle, both OsSPS1 and OsSPS11 promoter activities were low in the dark and increased rapidly after the beginning of the light period. When the transgenic rice plants were moved to the continuous light condition, both P OsSPS1 ::LUC and P OsSPS11 ::LUC reporter plants exhibited circadian bioluminescence rhythms; bioluminescence peaked during the subjective day with a 27-h period: in the early morning as for OsSPS1 promoter and midday for OsSPS11 promoter. These results indicate that these OsSPS promoters are controlled by both light illumination and circadian clock and that the regulatory mechanism of promoter activity differs between the two OsSPS genes.

The relationship between fatigue and light exposure during chemotherapy.

PubMed

Liu, Lianqi; Marler, Matthew R; Parker, Barbara A; Jones, Vicky; Johnson, Sherella; Cohen-Zion, Mairav; Fiorentino, Lavinia; Sadler, Georgia Robins; Ancoli-Israel, Sonia

2005-12-01

Fatigue is one of the most common and distressing complaints among cancer patients, not only during radiation and chemotherapy, but also for months to years after the completion of treatment. Fatigue interferes with patients' daily lives, reduces their quality of life, and is often a significant reason why patients discontinue treatment. We hypothesized that some of the fatigue may be related to disrupted circadian rhythms and low light exposure. The main objective of this study therefore was to investigate the association between fatigue and light exposure among patients with breast cancer. As part of a larger, ongoing prospective study on fatigue, sleep, and circadian rhythms in patients with breast cancer, an analysis of 63 women newly diagnosed with stage I-IIIA breast cancer and scheduled to receive four cycles of adjuvant or neoadjuvant anthracycline-based chemotherapy was conducted. Data were collected before and during weeks 1, 2, and 3 of cycle 1 and cycle 4. Fatigue was assessed using the Short Form of Multidimensional Fatigue Symptom Inventory. Light exposure was recorded with a wrist actigraph. There were significant correlations between fatigue levels and light exposure (r=-0.28 to -0.45) within both cycle 1 and cycle 4, such that higher levels of fatigue were associated with less light exposure. There were also significant correlations between changes in light exposure and changes in fatigue within the first 2 weeks of each cycle (r=-0.28 to -0.52). Increased fatigue was significantly correlated with decreased light exposure among patients with breast cancer. Although the cause and effect of exacerbated fatigue and decreased light exposure cannot be confirmed by the current study, and lower light exposure may just in part be due to the fatigued patients spending less time outdoors in bright light, two hypotheses are proposed about the mechanisms by which light may alleviate the fatigue of patients with breast cancer. These results suggest the need for prospective intervention studies of light therapy for breast-cancer-related fatigue.

The Impacts of Fluctuating Light on Crop Performance1[OPEN

PubMed Central

2018-01-01

Rapidly changing light conditions can reduce carbon gain and productivity in field crops because photosynthetic responses to light fluctuations are not instantaneous. Plant responses to fluctuating light occur across levels of organizational complexity from entire canopies to the biochemistry of a single reaction and across orders of magnitude of time. Although light availability and variation at the top of the canopy are largely dependent on the solar angle and degree of cloudiness, lower crop canopies rely more heavily on light in the form of sunflecks, the quantity of which depends mostly on canopy structure but also may be affected by wind. The ability of leaf photosynthesis to respond rapidly to these variations in light intensity is restricted by the relatively slow opening/closing of stomata, activation/deactivation of C3 cycle enzymes, and up-regulation/down-regulation of photoprotective processes. The metabolic complexity of C4 photosynthesis creates the apparently contradictory possibilities that C4 photosynthesis may be both more and less resilient than C3 to dynamic light regimes, depending on the frequency at which these light fluctuations occur. We review the current understanding of the underlying mechanisms of these limitations to photosynthesis in fluctuating light that have shown promise in improving the response times of photosynthesis-related processes to changes in light intensity. PMID:29192028

A component of retinal light adaptation mediated by the thyroid hormone cascade.

PubMed

Bedolla, Diana E; Torre, Vincent

2011-01-01

Analysis with DNA-microrrays and real time PCR show that several genes involved in the thyroid hormone cascade, such as deiodinase 2 and 3 (Dio2 and Dio3) are differentially regulated by the circadian clock and by changes of the ambient light. The expression level of Dio2 in adult rats (2-3 months of age) kept continuously in darkness is modulated by the circadian clock and is up-regulated by 2 fold at midday. When the diurnal ambient light was on, the expression level of Dio2 increased by 4-8 fold and a consequent increase of the related protein was detected around the nuclei of retinal photoreceptors and of neurons in inner and outer nuclear layers. The expression level of Dio3 had a different temporal pattern and was down-regulated by diurnal light. Our results suggest that DIO2 and DIO3 have a role not only in the developing retina but also in the adult retina and are powerfully regulated by light. As the thyroid hormone is a ligand-inducible transcription factor controlling the expression of several target genes, the transcriptional activation of Dio2 could be a novel genomic component of light adaptation.

A Component of Retinal Light Adaptation Mediated by the Thyroid Hormone Cascade

PubMed Central

Bedolla, Diana E.; Torre, Vincent

2011-01-01

Analysis with DNA-microrrays and real time PCR show that several genes involved in the thyroid hormone cascade, such as deiodinase 2 and 3 (Dio2 and Dio3) are differentially regulated by the circadian clock and by changes of the ambient light. The expression level of Dio2 in adult rats (2–3 months of age) kept continuously in darkness is modulated by the circadian clock and is up-regulated by 2 fold at midday. When the diurnal ambient light was on, the expression level of Dio2 increased by 4–8 fold and a consequent increase of the related protein was detected around the nuclei of retinal photoreceptors and of neurons in inner and outer nuclear layers. The expression level of Dio3 had a different temporal pattern and was down-regulated by diurnal light. Our results suggest that DIO2 and DIO3 have a role not only in the developing retina but also in the adult retina and are powerfully regulated by light. As the thyroid hormone is a ligand-inducible transcription factor controlling the expression of several target genes, the transcriptional activation of Dio2 could be a novel genomic component of light adaptation. PMID:22039463

Aberrant light directly impairs mood and learning through melanopsin-expressing neurons.

PubMed

LeGates, Tara A; Altimus, Cara M; Wang, Hui; Lee, Hey-Kyoung; Yang, Sunggu; Zhao, Haiqing; Kirkwood, Alfredo; Weber, E Todd; Hattar, Samer

2012-11-22

The daily solar cycle allows organisms to synchronize their circadian rhythms and sleep-wake cycles to the correct temporal niche. Changes in day-length, shift-work, and transmeridian travel lead to mood alterations and cognitive function deficits. Sleep deprivation and circadian disruption underlie mood and cognitive disorders associated with irregular light schedules. Whether irregular light schedules directly affect mood and cognitive functions in the context of normal sleep and circadian rhythms remains unclear. Here we show, using an aberrant light cycle that neither changes the amount and architecture of sleep nor causes changes in the circadian timing system, that light directly regulates mood-related behaviours and cognitive functions in mice. Animals exposed to the aberrant light cycle maintain daily corticosterone rhythms, but the overall levels of corticosterone are increased. Despite normal circadian and sleep structures, these animals show increased depression-like behaviours and impaired hippocampal long-term potentiation and learning. Administration of the antidepressant drugs fluoxetine or desipramine restores learning in mice exposed to the aberrant light cycle, suggesting that the mood deficit precedes the learning impairments. To determine the retinal circuits underlying this impairment of mood and learning, we examined the behavioural consequences of this light cycle in animals that lack intrinsically photosensitive retinal ganglion cells. In these animals, the aberrant light cycle does not impair mood and learning, despite the presence of the conventional retinal ganglion cells and the ability of these animals to detect light for image formation. These findings demonstrate the ability of light to influence cognitive and mood functions directly through intrinsically photosensitive retinal ganglion cells.

Effect of LED photobiomodulation on fluorescent light induced changes in cellular ATPases and Cytochrome c oxidase activity in Wistar rat.

PubMed

A, Ahamed Basha; C, Mathangi D; R, Shyamala

2016-12-01

Fluorescent light exposure at night alters cellular enzyme activities resulting in health defects. Studies have demonstrated that light emitting diode photobiomodulation enhances cellular enzyme activities. The objectives of this study are to evaluate the effects of fluorescent light induced changes in cellular enzymes and to assess the protective role of pre exposure to 670 nm LED in rat model. Male Wistar albino rats were divided into 10 groups of 6 animals each based on duration of exposure (1, 15, and 30 days) and exposure regimen (cage control, exposure to fluorescent light [1800 lx], LED preexposure followed by fluorescent light exposure and only LED exposure). Na + -K + ATPase, Ca 2+ ATPase, and cytochrome c oxidase of the brain, heart, kidney, liver, and skeletal muscle were assayed. Animals of the fluorescent light exposure group showed a significant reduction in Na + -K + ATPase and Ca 2+ ATPase activities in 1 and 15 days and their increase in animals of 30-day group in most of the regions studied. Cytochrome c oxidase showed increase in their level at all the time points assessed in most of the tissues. LED light preexposure showed a significant enhancement in the degree of increase in the enzyme activities in almost all the tissues and at all the time points assessed. This study demonstrates the protective effect of 670 nm LED pre exposure on cellular enzymes against fluorescent light induced change.

Fluorescent light induces neurodegeneration in the rodent nigrostriatal system but near infrared LED light does not.

PubMed

Romeo, Stefania; Vitale, Flora; Viaggi, Cristina; di Marco, Stefano; Aloisi, Gabriella; Fasciani, Irene; Pardini, Carla; Pietrantoni, Ilaria; Di Paolo, Mattia; Riccitelli, Serena; Maccarone, Rita; Mattei, Claudia; Capannolo, Marta; Rossi, Mario; Capozzo, Annamaria; Corsini, Giovanni U; Scarnati, Eugenio; Lozzi, Luca; Vaglini, Francesca; Maggio, Roberto

2017-05-01

We investigated the effects of continuous artificial light exposure on the mouse substantia nigra (SN). A three month exposure of C57Bl/6J mice to white fluorescent light induced a 30% reduction in dopamine (DA) neurons in SN compared to controls, accompanied by a decrease of DA and its metabolites in the striatum. After six months of exposure, neurodegeneration progressed slightly, but the level of DA returned to the basal level, while the metabolites increased with respect to the control. Three month exposure to near infrared LED light (∼710nm) did not alter DA neurons in SN, nor did it decrease DA and its metabolites in the striatum. Furthermore mesencephalic cell viability, as tested by [ 3 H]DA uptake, did not change. Finally, we observed that 710nm LED light, locally conveyed in the rat SN, could modulate the firing activity of extracellular-recorded DA neurons. These data suggest that light can be detrimental or beneficial to DA neurons in SN, depending on the source and wavelength. Copyright © 2017 Elsevier B.V. All rights reserved.

Using Optically Stimulated Electron Emission as an Inspection Method to Monitor Surface Contamination

NASA Technical Reports Server (NTRS)

Lingbloom, Mike S.

2008-01-01

During redesign of the Space Shuttle reusable solid rocket motor (RSRM), NASA amended the contract with ATK Launch Systems (then Morton Thiokol Inc.) with Change Order 966 to implement a contamination control and cleanliness verification method. The change order required: (1) A quantitative inspection method (2) A written record of actual contamination levels versus a known reject level (3) A method that is more sensitive than existing methods of visual and black light inspection. Black light inspection is only useful for inspection of contaminants that fluoresce near the 365 nm spectral line and is not useful for inspection of most silicones that will not produce strong fluorescence. Black light inspection conducted by a qualified inspector under controlled light is capable of detecting Conoco HD-2 grease in gross amounts and is very subjective due to operator sensitivity. Optically stimulated electron emission (OSEE), developed at the Materials and Process Laboratory at Marshall Space Flight Center (MSFC), was selected to satisfy Change Order 966. OSEE offers several important advantages over existing laboratory methods with similar sensitivity, e.g., spectroscopy and nonvolatile residue sampling, which provide turn around time, real time capability, and full coverage inspection capability. Laboratory methods require sample gathering and in-lab analysis, which sometimes takes several days to get results. This is not practical in a production environment. In addition, these methods do not offer full coverage inspection of the large components

Design of control system based on SCM music fountain

NASA Astrophysics Data System (ADS)

Li, Biqing; Li, Zhao; Jiang, Suping

2018-06-01

The design of the design of a microprocessor controlled by simple circuit, introduced this design applied to the components, and draw the main flow chart presentation. System is the use of an external music source, the intensity of the input audio signal lights will affect the light off, the fountain spray of water level will be based on changes in the lantern light off. This design uses a single-chip system is simple, powerful, good reliability and low cost.

Computational Modeling to Limit the Impact Displays and Indicator Lights Have on Habitable Volume Operational Lighting Constraints

NASA Technical Reports Server (NTRS)

Clark, T. A.; Salazar, G. A.; Brainard, G. C.; Kolomenski, A.; Hanifin, J.; Schwin, B. M.

2017-01-01

NASA has demonstrated an interest in improving astronaut health and performance through the installment of a new lighting countermeasure on the International Space Station. The Solid State Lighting Assembly (SSLA) system is designed to positively influence astronaut health by providing a daily change to light spectrum to improve circadian entrainment. Unfortunately, existing NASA standards and requirements define ambient light level requirements for crew sleep and other tasks, yet the number of light-emitting diode (LED) indicators and displays within a habitable volume is currently uncontrolled. Because each of these light sources has its own unique spectral properties, the additive lighting environment ends up becoming something different from what was planned or researched. Restricting the use of displays and indicators is not a solution because these systems provide beneficial crew feedback.

Cylindrospermopsin induced changes in growth, toxin production and antioxidant response of Acutodesmus acuminatus and Microcystis aeruginosa under differing light and nitrogen conditions.

PubMed

Chia, Mathias Ahii; Cordeiro-Araújo, Micheline Kézia; Lorenzi, Adriana Sturion; Bittencourt-Oliveira, Maria do Carmo

2017-08-01

Growing evidence suggests that some bioactive metabolites (e.g. cyanotoxins) produced by cyanobacteria have allelopathic potential, due to their inhibitory or stimulatory effects on competing species. Although a number of studies have shown that the cyanotoxin cylindrospermopsin (CYN) has variable effects on phytoplankton species, the impact of changing physicochemical conditions on its allelopathic potential is yet to be investigated. We investigated the physiological response of Microcystis aeruginosa (Cyanobacteria) and Acutodesmus acuminatus (Chlorophyta) to CYN under varying nitrogen and light conditions. At 24h, higher microcystins content of M. aeruginosa was recorded under limited light in the presence of CYN, while at 120h the lower levels of the toxins were observed in the presence of CYN under optimum light. Total MCs concentration was significantly (p<0.05) lowered by CYN after 120h of exposure under limited and optimum nitrogen conditions. On the other hand, there were no significant (p>0.05) changes in total MCs concentrations after exposure to CYN under high nitrogen conditions. As expected, limited light and limited nitrogen conditions resulted in lower cell density of both species, while CYN only significantly (p<0.05) inhibited the growth of M. aeruginosa. Regardless of the light or nitrogen condition, the presence of CYN increased internal H 2 O 2 content of both species, which resulted in significant (p<0.05) changes in antioxidant enzyme (catalase, peroxidase, superoxide dismutase and glutathione S-transferase) activities. The oxidative stress caused by CYN was higher under limited light and limited nitrogen. These results showed that M. aeruginosa and A. acuminatus have variable response to CYN under changing light and nitrogen conditions, and demonstrate that need to consider changes in physicochemical conditions during ecotoxicological and ecophysiological investigations. Copyright © 2017 Elsevier Inc. All rights reserved.

Fluorescent protein-mediated colour polymorphism in reef corals: multicopy genes extend the adaptation/acclimatization potential to variable light environments.

PubMed

Gittins, John R; D'Angelo, Cecilia; Oswald, Franz; Edwards, Richard J; Wiedenmann, Jörg

2015-01-01

The genomic framework that enables corals to adjust to unfavourable conditions is crucial for coral reef survival in a rapidly changing climate. We have explored the striking intraspecific variability in the expression of coral pigments from the green fluorescent protein (GFP) family to elucidate the genomic basis for the plasticity of stress responses among reef corals. We show that multicopy genes can greatly increase the dynamic range over which corals can modulate transcript levels in response to the light environment. Using the red fluorescent protein amilFP597 in the coral Acropora millepora as a model, we demonstrate that its expression increases with light intensity, but both the minimal and maximal gene transcript levels vary markedly among colour morphs. The pigment concentration in the tissue of different morphs is strongly correlated with the number of gene copies with a particular promoter type. These findings indicate that colour polymorphism in reef corals can be caused by the environmentally regulated expression of multicopy genes. High-level expression of amilFP597 is correlated with reduced photodamage of zooxanthellae under acute light stress, supporting a photoprotective function of this pigment. The cluster of light-regulated pigment genes can enable corals to invest either in expensive high-level pigmentation, offering benefits under light stress, or to rely on low tissue pigment concentrations and use the conserved resources for other purposes, which is preferable in less light-exposed environments. The genomic framework described here allows corals to pursue different strategies to succeed in habitats with highly variable light stress levels. In summary, our results suggest that the intraspecific plasticity of reef corals' stress responses is larger than previously thought. © 2014 The Authors Molecular Ecology Published by John Wiley & Sons Ltd.

Protective Effect of Proanthocyanidins from Sea Buckthorn (Hippophae Rhamnoides L.) Seed against Visible Light-Induced Retinal Degeneration in Vivo.

PubMed

Wang, Yong; Zhao, Liang; Huo, Yazhen; Zhou, Feng; Wu, Wei; Lu, Feng; Yang, Xue; Guo, Xiaoxuan; Chen, Peng; Deng, Qianchun; Ji, Baoping

2016-05-02

Dietary proanthocyanidins (PACs) as health-protective agents have become an important area of human nutrition research because of their potent bioactivities. We investigated the retinoprotective effects of PACs from sea buckthorn (Hippophae rhamnoides L.) seed against visible light-induced retinal degeneration in vivo. Pigmented rabbits were orally administered sea buckthorn seed PACs (50 and 100 mg/kg/day) for 14 consecutive days of pre-illumination and seven consecutive days of post-illumination. Retinal function was quantified via electroretinography 7 days after light exposure. Retinal damage was evaluated by measuring the thickness of the full-thickness retina and outer nuclear layer 7 days after light exposure. Sea buckthorn seed PACs significantly attenuated the destruction of electroretinograms and maintained the retinal structure. Increased retinal photooxidative damage was expressed by the depletion of glutathione peroxidase and catalase activities, the decrease of total antioxidant capacity level and the increase of malondialdehyde level. Light exposure induced a significant increase of inflammatory cytokines (IL-1β, TNF-α and IL-6) and angiogenesis (VEGF) levels in retina. Light exposure upregulated the expression of pro-apoptotic proteins Bax and caspase-3 and downregulated the expression of anti-apoptotic protein Bcl-2. However, sea buckthorn seed PACs ameliorated these changes induced by light exposure. Sea buckthorn seed PACs mediated the protective effect against light-induced retinal degeneration via antioxidant, anti-inflammatory and antiapoptotic mechanisms.

Protective Effect of Proanthocyanidins from Sea Buckthorn (Hippophae Rhamnoides L.) Seed against Visible Light-Induced Retinal Degeneration in Vivo

PubMed Central

Wang, Yong; Zhao, Liang; Huo, Yazhen; Zhou, Feng; Wu, Wei; Lu, Feng; Yang, Xue; Guo, Xiaoxuan; Chen, Peng; Deng, Qianchun; Ji, Baoping

2016-01-01

Dietary proanthocyanidins (PACs) as health-protective agents have become an important area of human nutrition research because of their potent bioactivities. We investigated the retinoprotective effects of PACs from sea buckthorn (Hippophae rhamnoides L.) seed against visible light-induced retinal degeneration in vivo. Pigmented rabbits were orally administered sea buckthorn seed PACs (50 and 100 mg/kg/day) for 14 consecutive days of pre-illumination and seven consecutive days of post-illumination. Retinal function was quantified via electroretinography 7 days after light exposure. Retinal damage was evaluated by measuring the thickness of the full-thickness retina and outer nuclear layer 7 days after light exposure. Sea buckthorn seed PACs significantly attenuated the destruction of electroretinograms and maintained the retinal structure. Increased retinal photooxidative damage was expressed by the depletion of glutathione peroxidase and catalase activities, the decrease of total antioxidant capacity level and the increase of malondialdehyde level. Light exposure induced a significant increase of inflammatory cytokines (IL-1β, TNF-α and IL-6) and angiogenesis (VEGF) levels in retina. Light exposure upregulated the expression of pro-apoptotic proteins Bax and caspase-3 and downregulated the expression of anti-apoptotic protein Bcl-2. However, sea buckthorn seed PACs ameliorated these changes induced by light exposure. Sea buckthorn seed PACs mediated the protective effect against light-induced retinal degeneration via antioxidant, anti-inflammatory and antiapoptotic mechanisms. PMID:27144578

A lighting assembly based on red and blue light-emitting diodes as a lighting source for space agriculture

NASA Astrophysics Data System (ADS)

Avercheva, Olga; Berkovich, Yuliy A.; Smolyanina, Svetlana; Bassarskaya, Elizaveta; Zhigalova, Tatiana; Ptushenko, Vasiliy; Erokhin, Alexei

Light-emitting diodes (LEDs) are a promising lighting source for space agriculture due to their high efficiency, longevity, safety, and other factors. Assemblies based on red and blue LEDs have been recommended in literature, although not all plants show sufficient productivity in such lighting conditions. Adding of green LEDs proposed in some works was aimed at psychological support for the crew, and not at the improvement of plant growth. We studied the growth and the state of the photosynthetic apparatus in Chinese cabbage (Brassica chinensis L.) plants grown under red (650 nm) and blue (470 nm) light-emitting diodes (LEDs). Plants grown under a high-pressure sodium lamp (HPS lamp) were used as a control. The plants were illuminated with two photosynthetic photon flux levels: nearly 400 µE and about 100 µE. Plants grown under LEDs with 400 µE level, as compared to control plants, showed lower fresh weight, edible biomass, growth rate, and sugar content. The difference in fresh weight and edible biomass was even more pronounced in plants grown with 100 µE level; the data indicate that the adaptability of the test plants to insufficient lighting decreased. Under LEDs, we observed the decreasing of root growth and the absence of transition to the flowering stage, which points to a change in the hormonal balance in plants grown in such lighting conditions. We also found differences in the functioning of the photosynthetic apparatus and its reaction to a low lighting level. We have concluded that a lighting assembly with red and blue LEDs only is insufficient for the plant growth and productivity, and can bring about alterations in their adaptive and regulatory mechanisms. Further studies are needed to optimize the lighting spectrum for space agriculture, taking into account the photosynthetic, phototropic and regulatory roles of light. Using white LEDs or adding far-red and green LEDs might be a promising approach.

The redox state of the apoplast influences the acclimation of photosynthesis and leaf metabolism to changing irradiance

PubMed Central

Karpinska, Barbara; Zhang, Kaiming; Rasool, Brwa; Pastok, Daria; Morris, Jenny; Verrall, Susan R.; Hedley, Pete E.

2017-01-01

Abstract The redox state of the apoplast is largely determined by ascorbate oxidase (AO) activity. The influence of AO activity on leaf acclimation to changing irradiance was explored in wild‐type (WT) and transgenic tobacco (Nicotiana tobaccum) lines containing either high [pumpkin AO (PAO)] or low [tobacco AO (TAO)] AO activity at low [low light (LL); 250 μmol m−2 s−1] and high [high light (HL); 1600 μmol m−2 s−1] irradiance and following the transition from HL to LL. AO activities changed over the photoperiod, particularly in the PAO plants. AO activity had little effect on leaf ascorbate, which was significantly higher under HL than under LL. Apoplastic ascorbate/dehydroascorbate (DHA) ratios and threonate levels were modified by AO activity. Despite decreased levels of transcripts encoding ascorbate synthesis enzymes, leaf ascorbate increased over the first photoperiod following the transition from HL to LL, to much higher levels than LL‐grown plants. Photosynthesis rates were significantly higher in the TAO leaves than in WT or PAO plants grown under HL but not under LL. Sub‐sets of amino acids and fatty acids were lower in TAO and WT leaves than in the PAO plants under HL, and following the transition to LL. Light acclimation processes are therefore influenced by the apoplastic as well as chloroplastic redox state. PMID:28369975

Progressing from Light Experimentation to Heavy Episodic Drinking in Early and Middle Adolescence

PubMed Central

Guilamo-Ramos, Vincent; Turrisi, Rob; Jaccard, James; Wood, Elizabeth; Gonzalez, Bernardo

2010-01-01

Objective Few studies have examined psychological variables related to changes in drinking patterns from light experimentation with alcohol to heavy episodic drinking in early and middle adolescence. The present study examined parental and peer influences, gender and grade level as predictors of such changes in adolescent alcohol consumption. Method Approximately 1,420 light drinkers were analyzed from Wave 1 of the National Longitudinal Study of Adolescent Health (Add Health). Heavy episodic drinking activity was assessed 1 year later. Results Gender differences in transitions to heavy episodic drinking were observed, with males being more likely than females to make a transition. Parent parameter setting and communication variables, as well as peer variables at different grade levels, buffered these gender differences. Conclusions Adolescents who are light experimenters represent a high-risk group as a consequence of their initial consumption tendencies. Some of these adolescents graduated beyond simple experimentation and moved into patterns of consumption that could be considered dangerous. Our analyses implicated an array of parental-based buffers: parent involvement in the adolescent’s life, development of good communication patterns and expressions of warmth and affection. Minimizing associations with peers who consume alcohol may also have a buffering effect. There was evidence that these buffers may dampen gender differences not so much by affecting female drinking tendencies as by keeping males at reduced levels of alcohol consumption comparable to those of females. PMID:15376824

Non-destructive plant health sensing using absorption spectroscopy

NASA Technical Reports Server (NTRS)

Bledsoe, Jim; Manukian, Ara; Pearce, Michael; Weiss, Lee

1988-01-01

The sensor group of the 1988 EGM 4001 class, working on NASA's Controlled Ecological Life Support Systems (CELSS) project, investigated many different plant health indicators and the technologies used to test them. The project selected by the group was to measure chlorophyll levels using absorption spectroscopy. The spectrometer measures the amount of chlorophyll in a leaf by measuring the intensity of light of a specific wavelength that is passed through a leaf. The three wavelengths of light being used corresponded to the near-IR absorption peaks of chlorophyll a, chlorophyll b, and chlorophyll-free structures. Experimentation showed that the sensor is indeed measuring levels of chlorophyll a and b and their changes before the human eye can see any changes. The detector clamp causes little damage to the leaf and will give fairly accurate readings on similar locations on a leaf, freeing the clamp from having to remain on the same spot of a leaf for all measurements. External light affects the readings only slightly so that measurements may be taken in light or dark environments. Future designs and experimentation will concentrate on reducing the size of the sensor and adapting it to a wider range of plants.

Development of an ultralow-light-level luminescence image analysis system for dynamic measurements of transcriptional activity in living and migrating cells.

PubMed

Maire, E; Lelièvre, E; Brau, D; Lyons, A; Woodward, M; Fafeur, V; Vandenbunder, B

2000-04-10

We have developed an approach to study in single living epithelial cells both cell migration and transcriptional activation, which was evidenced by the detection of luminescence emission from cells transfected with luciferase reporter vectors. The image acquisition chain consists of an epifluorescence inverted microscope, connected to an ultralow-light-level photon-counting camera and an image-acquisition card associated to specialized image analysis software running on a PC computer. Using a simple method based on a thin calibrated light source, the image acquisition chain has been optimized following comparisons of the performance of microscopy objectives and photon-counting cameras designed to observe luminescence. This setup allows us to measure by image analysis the luminescent light emitted by individual cells stably expressing a luciferase reporter vector. The sensitivity of the camera was adjusted to a high value, which required the use of a segmentation algorithm to eliminate the background noise. Following mathematical morphology treatments, kinetic changes of luminescent sources were analyzed and then correlated with the distance and speed of migration. Our results highlight the usefulness of our image acquisition chain and mathematical morphology software to quantify the kinetics of luminescence changes in migrating cells.

Reduction of lighting energy consumption in office buildings through improved daylight design

NASA Astrophysics Data System (ADS)

Papadouri, Maria Violeta Prado

This study aims to investigate the lighting energy consumption in office buildings and the options for its reduction. One way to reduce lighting energy consumption is by improving the daylight design. A better use of daylight in buildings might be an outcome from the effort made in different directions. Like the improvement of a building's fabric and layout, the materials, even the furniture in a space influences the daylight quality considerably. Also very important role in lighting energy consumption has the development of more efficient lighting technology like the electric lighting control systems, such as photo sensors and occupancy sensors. Both systems are responsible so that the electric light is not used without reason. As the focusing area of this study, is to find ways to improve the daylight use in buildings, a consequent question is which are the methods provided in order to achieve this The accuracy of the methodology used is also an important issue in order to achieve reliable results. The methodology applied in this study includes the analysis of a case study by taking field measurements and computer simulations. The first stage included gathering information about the lighting design of the building and monitoring the light levels, both from natural and from the electric lighting. The second stage involved testing with computer simulations, different parameters that were expected to improve the daylight exploitation of the specific area. The results of the field measurements showed that the main problems of the space were the low natural light levels and the poor daylight distribution. The annual electric lighting energy consumption, as it was calculated with the use of computer simulations, represented the annual energy consumption of a typical air-conditioned prestige office building (energy consumption guide 19, for energy use in offices, 2000). After several computer simulations, the results showed that initial design parameters of the building can affect the lighting energy consumption of the space significantly. On the other hand, relatively small changes, like changing the reflectance of the surfaces and the lighting control systems can make even more difference to the light quality of the space and the reduction of lighting energy consumption.

Electronic properties of light-induced recombination centers in boron-doped Czochralski silicon

NASA Astrophysics Data System (ADS)

Schmidt, Jan; Cuevas, Andrés

1999-09-01

In order to study the electronic properties of the recombination centers responsible for the light-induced carrier lifetime degradation commonly observed in high-purity boron-doped Czochralski (Cz) silicon, injection-level dependent carrier lifetime measurements are performed on a large number of boron-doped p-type Cz silicon wafers of various resistivities (1-31 Ω cm) prior to and after light degradation. The measurement technique used is the contactless quasi-steady-state photoconductance method, allowing carrier lifetime measurements over a very broad injection range between 1012 and 1017cm-3. To eliminate all recombination channels not related to the degradation effect, the difference of the inverse lifetimes measured after and before light degradation is evaluated. A detailed analysis of the injection level dependence of the carrier lifetime change using the Shockley-Read-Hall theory shows that the fundamental recombination center created during illumination has an energy level between Ev+0.35 and Ec-0.45 eV and an electron/hole capture time constant ratio between 0.1 and 0.2. This deep-level center is observed in all samples and is attributed to a new type of boron-oxygen complex. Besides this fundamental defect, in some samples an additional shallow-level recombination center at 0.15 eV below Ec or above Ev is found to be activated during light exposure. This second center dominates the light-degraded carrier lifetime only under high-injection conditions and is hence only of minor importance for low-injection operated devices.

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

PubMed

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 blue light energy levels below the damage threshold. Therefore, applied blue light intensities below the characterized damage threshold might define a therapeutic blue light tolerance range. Copyright © 2015 Elsevier Ltd. All rights reserved.

Night myopia is reduced in binocular vision.

PubMed

Chirre, Emmanuel; Prieto, Pedro M; Schwarz, Christina; Artal, Pablo

2016-06-01

Night myopia, which is a shift in refraction with light level, has been widely studied but still lacks a complete understanding. We used a new infrared open-view binocular Hartmann-Shack wave front sensor to quantify night myopia under monocular and natural binocular viewing conditions. Both eyes' accommodative response, aberrations, pupil diameter, and convergence were simultaneously measured at light levels ranging from photopic to scotopic conditions to total darkness. For monocular vision, reducing the stimulus luminance resulted in a progression of the accommodative state that tends toward the subject's dark focus or tonic accommodation and a change in convergence following the induced accommodative error. Most subjects presented a myopic shift of accommodation that was mitigated in binocular vision. The impact of spherical aberration on the focus shift was relatively small. Our results in monocular conditions support the hypothesis that night myopia has an accommodative origin as the eye progressively changes its accommodation state with decreasing luminance toward its resting state in total darkness. On the other hand, binocularity restrains night myopia, possibly by using fusional convergence as an additional accommodative cue, thus reducing the potential impact of night myopia on vision at low light levels.

Fiber optic moisture sensor

DOEpatents

Kirkham, R.R.

1984-08-03

A method and apparatus for sensing moisture changes by utilizing optical fiber technology. One embodiment uses a reflective target at the end of an optical fiber. The reflectance of the target varies with its moisture content and can be detected by a remote unit at the opposite end of the fiber. A second embodiment utilizes changes in light loss along the fiber length. This can be attributed to changes in reflectance of cladding material as a function of its moisture content. It can also be affected by holes or inserts interposed in the cladding material and/or fiber. Changing light levels can also be coupled from one fiber to another in an assembly of fibers as a function of varying moisture content in their overlapping lengths of cladding material.

Control of light-dependent keto carotenoid biosynthesis in Nostoc 7120 by the transcription factor NtcA.

PubMed

Sandmann, Gerhard; Mautz, Jürgen; Breitenbach, Jürgen

2016-09-01

In Nostoc PCC 7120, two different ketolases, CrtW and CrtO are involved in the formation of keto carotenoids from β-carotene. In contrast to other cyanobacteria, CrtW catalyzes the formation of monoketo echinenone whereas CrtO is the only enzyme for the synthesis of diketo canthaxanthin. This is the major photo protective carotenoid in this cyanobacterium. Under high-light conditions, basic canthaxanthin formation was transcriptionally up-regulated. Upon transfer to high light, the transcript levels of all investigated carotenogenic genes including those coding for phytoene synthase, phytoene desaturase and both ketolases were increased. These transcription changes proceeded via binding of the transcription factor NtcA to the promoter regions of the carotenogenic genes. The binding was absolutely dependent on the presence of reductants and oxo-glutarate. Light-stimulated transcript formation was inhibited by DCMU. Therefore, photosynthetic electron transport is proposed as the sensor for high-light and a changing redox state as a signal for NtcA binding.

Correlation of molecular expression with diel rhythm of oviposition in Calliphora vicina (Robineau-Desvoidy) (Diptera: Calliphoridae) and implications for forensic entomology.

PubMed

George, Kelly A; Archer, Melanie S; Toop, Tes

2015-01-01

This study explored the molecular mechanisms potentially underlying blow fly nocturnal oviposition. A behavioral study revealed that Calliphora vicina (Robineau-Desvoidy) (Diptera: Calliphoridae) possesses a diel rhythm of oviposition in light under 12:12 light/dark conditions. Reversal to 12:12 dark/light resulted in oviposition behavior changing to align with the adjusted regime in most females, but four of 59 experimental females lacked a diel rhythm of oviposition (were arrhythmic). Real-time PCR was used to monitor the molecular expression levels of known circadian genes per and tim in C. vicina to determine whether gene expression and behavior correlated. As with behavior, reversing light/dark conditions changed rhythmic gene expression to align with an adjusted light regime. This suggests that although it is unlikely that C. vicina will colonize dead bodies at night, arrhythmic females and oviposition in the dark was demonstrated. © 2014 American Academy of Forensic Sciences.

Anthropogenic noise, but not artificial light levels predicts song behaviour in an equatorial bird.

PubMed

Dorado-Correa, Adriana M; Rodríguez-Rocha, Manuel; Brumm, Henrik

2016-07-01

Birds in cities start singing earlier in the morning than in rural areas; commonly this shift is attributed to light pollution. Some studies have suggested that traffic noise has a stronger influence on singing activity than artificial light does. Changes in the timing of singing behaviour in relation to noise and light pollution have only been investigated in the temperate zones. Tropical birds, however, experience little seasonal variation in day length and may be less dependent on light intensity as a modifier for reproductive behaviours such as song. To test whether noise or light pollution has a stronger impact on the dawn chorus of a tropical bird, we investigated the singing behaviour of rufous-collared sparrows (Zonotrichia capensis) in Bogota, Colombia at two times during the year. We found that birds in places with high noise levels started to sing earlier. Light pollution did not have a significant effect. Birds may begin to sing earlier in noisy areas to avoid acoustic masking by traffic later in the morning. Our results also suggest that some tropical birds may be less sensitive to variations in day length and thus less sensitive to light pollution.

Light Regulation of Brassinosteroid Signaling Components: Checking Regulation of Protein Stability in Darkness.

PubMed

Corvalán, Claudia; Choe, Sunghwa

2017-01-01

Environmental conditions can affect stability of proteins at transcriptional or posttranscriptional levels to modulate their functions. Here we describe a method to observe changes in protein stability under different light conditions. In brief, Arabidopsis thaliana seedlings were maintained under various light regimes from continuous light to total darkness or transitions from light to dark, whereafter total protein was extracted from plants. Proteins were measured and resolved on sodium dodecyl sulfate-polyacrylamide gels and transferred to polyvinylidene difluoride membranes. Blots were incubated with the corresponding antibodies for the visualization of protein bands. The protocol described has been successfully applied in wild-type, different transgenic, and mutant background plants to study how light alone or in combination with other factors influences protein stability.

Artificial light alters natural regimes of night-time sky brightness

PubMed Central

Davies, Thomas W.; Bennie, Jonathan; Inger, Richard; Gaston, Kevin J.

2013-01-01

Artificial light is globally one of the most widely distributed forms of anthropogenic pollution. However, while both the nature and ecological effects of direct artificial lighting are increasingly well documented, those of artificial sky glow have received little attention. We investigated how city lights alter natural regimes of lunar sky brightness using a novel ten month time series of measurements recorded across a gradient of increasing light pollution. In the city, artificial lights increased sky brightness to levels six times above those recorded in rural locations, nine and twenty kilometers away. Artificial lighting masked natural monthly and seasonal regimes of lunar sky brightness in the city, and increased the number and annual regime of full moon equivalent hours available to organisms during the night. The changes have potentially profound ecological consequences.

Digestive efficiency, free amino acid pools and quality of growth performance in Atlantic salmon (Salmo salar L.) affected by light regimes and vaccine types.

PubMed

Rungruangsak-Torrissen, Krisna; Sunde, Jan; Berg, Arne Erik; Nordgarden, Ulla; Fjelldal, Per Gunnar; Oppedal, Frode

2009-06-01

This study comprised the results of three different seawater trials using unique combination of techniques to study protease digestive efficiency and growth performance quality to illustrate the effects of light regimes and vaccine types in Atlantic salmon (Salmo salar L.). Fish with higher growth had higher trypsin (T) and chymotrypsin (C) specific activities with higher T/C ratio or slope T/C ratio [calculated from the regression between trypsin (y) and chymotrypsin (x) specific activities] in the pyloric caeca. The T/C ratios indicated fish growth rates over a period of 1-2 months, while the slope T/C ratios indicated fish growth rates at sampling. Adaptation period for adjustment to the new environment of continuous light was 70 days, indicated by the differences in trypsin specific activities and the crossing of slope T/C ratio regressions following with the changes in growth rate directions between the control and the treated group. Vaccine types affected fish vertebral growth, and additional continuous light enhanced the impact of vaccines on fish growth during springtime, indicated by differences in slope T/C ratios. Continuous light stimulated fish growth during winter to spring, when the natural day length was short, without significantly changing white muscle and oocyte qualities in the fish of about 500 g, except for significantly increased white muscle RNA concentration. Continuous light also reduced fish growth rate later during summer, when the natural day length was long, by precedently decreasing the T/C ratio in late spring. Interestingly, plasma levels of free lysine related to tryptic digestion were correlated with trypsin specific activity levels. Continuous light caused higher levels of most free amino acids (FAA) involved in nitrogen metabolism, higher incorporation of essential FAA for protein synthesis, and higher protein turnover rate (free hydroxyproline levels) in both plasma and white muscle. However, continuous light did not affect higher protein content, intracellular buffering capacity and RNA levels in the white muscle of the fish of about 1 kg, probably due to limitation of FAA available for protein synthesis. It is therefore suggested that enhancing fish growth by continuous light stimulation should be accompanied by increasing availability or content of dietary protein (and probably minerals), which in turn would improve the quality of fish growth performance through increasing fillet protein concentration, strengthening vertebral growth, and delaying oocyte development.

Influence of benzoporphyrin-derivative monoacid ring A (BPD-MA, verteporfin) on murine dendritic cells

NASA Astrophysics Data System (ADS)

Hunt, David W. C.; King, Diane E.; Levy, Julia G.

1997-05-01

The impact of bensoporphyrin derivative monoacid ring A, and visible light was determined for mouse splenic dendritic cells (DC), potent antigen-presenting cells (APC) of the immune system. It was discovered that sub-lethal doses of BPD-MA and light significantly altered the surface receptor pattern of DC as well as diminishing the capacity of these cells to activate allogeneic T cells. Treatment of highly purified DC with BPD-MA and 690 nm wavelength light decreased DC expression of major histocompatibility (MHC) Class I and II antigens, leukocyte common antigen CD45, intercellular adhesion molecule-1 (ICAM-1, CD54), the co- stimulatory molecules CD80 and CD86, CD95 as well as integrin CD11c. In contrast, DC expression of leukocyte function-associated-1 (LFA-1, CD11a), CD11b, CD18, CD40, and the DC DEC-205 receptor increased after the treatment. Changes in receptor levels occurred rapidly. DC MHC Class I and ICAM-1 expression declined to 40 percent of control levels by 2 hours post-PDT. DC treated with BPD-MA and light were poor stimulators of allogeneic T cells in the mixed leukocyte reaction. BPD-MA, in the absence of light, had no effect on the immunostimulatory properties of these cells. The changes in DC receptor expression pattern produced by BPD-MA and light were comparable to those produced by ultraviolet B light, a treatment known to alter the immunostimulatory characteristics of DC. Photodynamic therapy with BPD-MA represents an innovative approach for the modification of immune reactivity.

Effects of VDT workstation lighting conditions on operator visual workload.

PubMed

Lin, Chiuhsiang Joe; Feng, Wen-Yang; Chao, Chin-Jung; Tseng, Feng-Yi

2008-04-01

Industrial lighting covers a wide range of different characteristics of working interiors and work tasks. This study investigated the effects of illumination on visual workload in visual display terminal (VDT) workstation. Ten college students (5 males and 5 females) were recruited as participants to perform VDT signal detection tasks. A randomized block design was utilized with four light colors (red, blue, green and white), two ambient illumination levels (20 lux and 340 lux), with the subject as the block. The dependent variables were the change of critical fusion frequency (CFF), visual acuity, reaction time of targets detection, error rates, and rating scores in a subjective questionnaire. The study results showed that both visual acuity and the subjective visual fatigue were significantly affected by the color of light. The illumination had significant effect on CFF threshold change and reaction time. Subjects prefer to perform VDT task under blue and white lights than green and red. Based on these findings, the study discusses and suggests ways of color lighting and ambient illumination to promote operators' visual performance and prevent visual fatigue effectively.

Experimental illumination of natural habitat—an experimental set-up to assess the direct and indirect ecological consequences of artificial light of different spectral composition

PubMed Central

Spoelstra, Kamiel; van Grunsven, Roy H. A.; Donners, Maurice; Gienapp, Phillip; Huigens, Martinus E.; Slaterus, Roy; Berendse, Frank; Visser, Marcel E.; Veenendaal, Elmar

2015-01-01

Artificial night-time illumination of natural habitats has increased dramatically over the past few decades. Generally, studies that assess the impact of artificial light on various species in the wild make use of existing illumination and are therefore correlative. Moreover, studies mostly focus on short-term consequences at the individual level, rather than long-term consequences at the population and community level—thereby ignoring possible unknown cascading effects in ecosystems. The recent change to LED lighting has opened up the exciting possibility to use light with a custom spectral composition, thereby potentially reducing the negative impact of artificial light. We describe here a large-scale, ecosystem-wide study where we experimentally illuminate forest-edge habitat with different spectral composition, replicated eight times. Monitoring of species is being performed according to rigid protocols, in part using a citizen-science-based approach, and automated where possible. Simultaneously, we specifically look at alterations in behaviour, such as changes in activity, and daily and seasonal timing. In our set-up, we have so far observed that experimental lights facilitate foraging activity of pipistrelle bats, suppress activity of wood mice and have effects on birds at the community level, which vary with spectral composition. Thus far, we have not observed effects on moth populations, but these and many other effects may surface only after a longer period of time. PMID:25780241

Effect of green light spectra on the reduction of retinal damage and stress in goldfish, Carassius auratus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Jin Ah; Kim, Na Na; Choi, Young Jae

We investigated the effect of light spectra on retinal damage and stress in goldfish using green (530 nm) and red (620 nm) light emitting diodes (LEDs) at three intensities each (0.5, 1.0, and 1.5 W/m{sup 2}). We measured the change in the levels of plasma cortisol and H{sub 2}O{sub 2} and expression and levels of caspase-3. The apoptotic response of green and red LED spectra was assessed using the terminal transferase dUTP nick end labeling (TUNEL) assay. Stress indicator (cortisol and H{sub 2}O{sub 2}) and apoptosis-related genes (caspase-3) decreased in green light, but increased in red light with higher light intensities over time.more » The TUNEL assay revealed that more apoptotic cells were detected in outer nuclear layers after exposure to red LED over time with the increase in light intensity, than the other spectra. These results indicate that green light efficiently reduces retinal damage and stress, whereas red light induces it. Therefore, red light-induced retina damage may induce apoptosis in goldfish retina. -- Highlights: •Green light efficiently reduces retinal damage and stress. •Green spectra reduce caspase production and apoptosis. •Red light-induced retina damage may induce apoptosis in goldfish retina. •The retina of goldfish recognizes green spectra as a stable environment.« less

Pluto's Atmosphere, Then and Now

NASA Astrophysics Data System (ADS)

Elliot, J. L.; Buie, M.; Person, M. J.; Qu, S.

2002-09-01

The KAO light curve for the 1988 stellar occultation by Pluto exhibits a sharp drop just below half light, but above this level the light curve is consistent with that of an isothermal atmosphere (T = 105 +/- 8 K, with N2 as its major constituent). The sharp drop in the light curve has been interpreted as being caused by: (i) a haze layer, (ii) a large thermal gradient, or (iii) some combination of these two. Modeling Pluto's atmosphere with a haze layer yields a normal optical depth >= 0.145 (Elliot & Young 1992, AJ 103, 991). On the other hand, if Pluto's atmosphere is assumed to be clear, the occultation light curve can be inverted with a new method that avoids the large-body approximations. Inversion of the KAO light curve with this method yields an upper isothermal part, followed by a sharp thermal gradient that reaches a maximum magnitude of -3.9 +/- 0.6 K km-1 at the end of the inversion (r = 1206 +/- 10 km). Even though we do not yet understand the cause of the sharp drop, the KAO light curve can be used as a benchmark for examining subsequent Pluto occultation light curves to determine whether Pluto's atmospheric structure has changed since 1988. As an example, the Mamiña light curve for the 2002 July 20 Pluto occultation of P126A was compared with the KAO light curve by Buie et al. (this conference), who concluded that Pluto's atmospheric structure has changed significantly since 1988. Further analysis and additional light curves from this and subsequent occultations (e.g. 2002 August 21) will allow us to elucidate the nature of these changes. This work was supported, in part, by grants from NASA (NAG5-9008 and NAG5-10444) and NSF (AST-0073447).

Does light pollution alter daylength? A test using light loggers on free-ranging European blackbirds (Turdus merula).

PubMed

Dominoni, Davide M; Partecke, Jesko

2015-05-05

Artificial light at night is one of the most apparent environmental changes accompanying anthropogenic habitat change. The global increase in light pollution poses new challenges to wild species, but we still have limited understanding of the temporal and spatial pattern of exposure to light at night. In particular, it has been suggested by several studies that animals exposed to light pollution, such as songbirds, perceive a longer daylength compared with conspecifics living in natural darker areas, but direct tests of such a hypothesis are still lacking. Here, we use a combination of light loggers deployed on individual European blackbirds, as well as automated radio-telemetry, to examine whether urban birds are exposed to a longer daylength than forest counterparts. We first used activity data from forest birds to determine the level of light intensity which defines the onset and offset of daily activity in rural areas. We then used this value as threshold to calculate the subjective perceived daylength of both forest and urban blackbirds. In March, when reproductive growth occurs, urban birds were exposed on average to a 49-min longer subjective perceived daylength than forest ones, which corresponds to a 19-day difference in photoperiod at this time of the year. In the field, urban blackbirds reached reproductive maturity 19 day earlier than rural birds, suggesting that light pollution could be responsible of most of the variation in reproductive timing found between urban and rural dwellers. We conclude that light at night is the most relevant change in ambient light affecting biological rhythms in avian urban-dwellers, most likely via a modification of the perceived photoperiod. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Does light pollution alter daylength? A test using light loggers on free-ranging European blackbirds (Turdus merula)

PubMed Central

Dominoni, Davide M.; Partecke, Jesko

2015-01-01

Artificial light at night is one of the most apparent environmental changes accompanying anthropogenic habitat change. The global increase in light pollution poses new challenges to wild species, but we still have limited understanding of the temporal and spatial pattern of exposure to light at night. In particular, it has been suggested by several studies that animals exposed to light pollution, such as songbirds, perceive a longer daylength compared with conspecifics living in natural darker areas, but direct tests of such a hypothesis are still lacking. Here, we use a combination of light loggers deployed on individual European blackbirds, as well as automated radio-telemetry, to examine whether urban birds are exposed to a longer daylength than forest counterparts. We first used activity data from forest birds to determine the level of light intensity which defines the onset and offset of daily activity in rural areas. We then used this value as threshold to calculate the subjective perceived daylength of both forest and urban blackbirds. In March, when reproductive growth occurs, urban birds were exposed on average to a 49-min longer subjective perceived daylength than forest ones, which corresponds to a 19-day difference in photoperiod at this time of the year. In the field, urban blackbirds reached reproductive maturity 19 day earlier than rural birds, suggesting that light pollution could be responsible of most of the variation in reproductive timing found between urban and rural dwellers. We conclude that light at night is the most relevant change in ambient light affecting biological rhythms in avian urban-dwellers, most likely via a modification of the perceived photoperiod. PMID:25780232

Alterations in circadian and meal-induced gut peptide levels in lean and obese rats.

PubMed

Moghadam, Alexander A; Moran, Timothy H; Dailey, Megan J

2017-12-01

Alterations in gut hormone signaling are a likely contributing factor to the metabolic disturbances associated with overweight/obesity as they coordinate the timing of feeding behavior, absorption, and utilization of nutrients. These hormones are released in response to food intake, or follow a circadian or anticipatory pattern of secretion that is independent of nutrient stimulation. The aim of this study was to identify the degree to which high-fat diet-induced obesity would alter the daily rhythm of gut peptide plasma levels (glucagon-like peptide-1 [GLP-1], peptide YY [PYY], insulin or amylin [AMY]) or meal-induced levels in the middle of the light or dark cycle. Male Sprague-Dawley rats were fed a high-fat diet (OBESE) or chow (LEAN), implanted with jugular catheters, and blood samples were taken every 2 h throughout the light/dark cycle while freely feeding or after an Ensure liquid meal. We found that even when OBESE and LEAN animals ate the same kcals and have a similar pattern of food intake, there is a difference in both the levels and rhythm of plasma gut peptides. GLP-1 and PYY are higher during the light cycle in LEAN animals and AMY is higher in the OBESE group throughout the light/dark cycle. There was also a differential response of plasma gut signals after the Ensure meal, even though the composition and amount of intake of the meal were the same in both groups. These changes occur prior to the high-fat diet induced loss of glycemic control and may be a target for early intervention. Impact statement The aim of this study was to test if obesity would alter the daily rhythm of gut peptides or meal-induced levels in the middle of the light or dark cycle. We found that even when animals are eating the same amount (in kcal) of food that the obese animals have altered daily rhythms and meal-induced gut peptide levels. In particular, we are the first to show that obesity induces increases in peptide YY levels during the light cycle and amylin remains high throughout the light and dark cycle in obese animals. These changes occurred prior to a loss of glycemic control. Thus, the rhythm of gut peptides could be used as an early indicator of later and more serious metabolic disturbances and may be a target for early intervention.

A self-photoprotection mechanism helps Stipa baicalensis adapt to future climate change

PubMed Central

Song, Xiliang; Zhou, Guangsheng; Xu, Zhenzhu; Lv, Xiaomin; Wang, Yuhui

2016-01-01

We examined the photosynthetic responses of Stipa baicalensis to relative long-term exposure (42 days) to the predicted elevated temperature and water availability changes to determine the mechanisms through which the plant would acclimate to future climate change. Two thermal regimes (ambient and +4 °C) and three irrigation levels (partial, normal and excess) were used in environmental control chambers. The gas exchange parameters, light response curves and A/Ci curves were determined. The elevated temperature and partial irrigation reduced the net photosynthetic rate due to a limitation in the photosynthetic capacity instead of the intercellular CO2 concentration. Partial irrigation decreased Rubisco activation and limited RuBP regeneration. The reduction in Vcmax increased with increasing temperature. Excess irrigation offset the negative effect of drought and led to a partial recovery of the photosynthetic capacity. Although its light use efficiency was restricted, the use of light and dark respiration by Stipa baicalensis was unchanged. We concluded that nonstomatal limitation was the primary reason for photosynthesis regulation in Stipa baicalensis under relative long-term climate change conditions. Although climate change caused reductions in the light use efficiency and photosynthetic rate, a self-photoprotection mechanism in Stipa baicalensis resulted in its high ability to maintain normal live activities. PMID:27161934

Mechanisms responsible for the photocurrent in bacteriorhodopsin

NASA Astrophysics Data System (ADS)

Alfinito, Eleonora; Reggiani, Lino

2015-03-01

Recently, there has been growing interest in the electrical properties of bacteriorhodopsin (bR), a protein belonging to the transmembrane protein family. Several experiments pointed out the role of green light in enhancing the current flow in nanolayers of bR, thus confirming potential applications of this protein in the field of optoelectronics. By contrast, the mechanisms underlying the charge transfer and the associated photocurrent are still far from being understood at a microscopic level. To take into account the structure-dependent nature of the current, in a previous set of papers we suggested a mechanism of sequential tunneling among neighboring amino acids. As a matter of fact, when irradiated with green light, bR undergoes a conformational change at a molecular level. Thus, the role played by the protein tertiary-structure in modeling the charge transfer cannot be neglected. The aim of this paper is to go beyond previous models, in the framework of a new branch of electronics we call proteotronics, which exploits the ability of using proteins as reliable, well-understood materials for the development of novel bioelectronic devices. In particular, the present approach assumes that the conformational change is not the unique transformation the protein undergoes when irradiated by light. Instead, the light can also promote an increase of the protein state free energy that, in turn, should modify its internal degree of connectivity. This phenomenon is here described by the change of the value of an interaction radius associated with the physical interactions among amino acids. The implemented model enables us to achieve a better agreement between theory and experiments in the region of a low applied bias by preserving the level of agreement at high values of applied bias. Furthermore, results provide new insights on the mechanisms responsible for bR photoresponse.

Investigation of the low-level modulated light action

NASA Astrophysics Data System (ADS)

Antonov, Sergei N.; Sotnikov, V. N.; Koreneva, L. G.

1994-07-01

Now there exists no clear complete knowledge about mechanisms and pathways by which low level laser bioactivation works. Modulated laser light action has been investigated two new ways: dynamical infrared thermography and computing image of living brain. These ways permit observation in real time laser action on peripheral blood flow, reflex reactions to functional probes, thermoregulation mechanisms as well as brain electrical activity changes of humans. We have designed a universal apparatus which produced all regimes of the output laser light. It has a built-in He-Ne laser with an acousto-optic modulator and an infrared GaAs laser. The device provided spatial combination of both the light beams and permitted us to irradiate an object both separately and simultaneously. This research shows that the most effective frequencies range from several to dozens of hertz. The duty factor and frequency scanning are also important. On the basis of these results in Russian clinics new treatment methods using modulated light are applied in practical neurology, gynecology, etc.

Plasma melatonin circadian rhythms during the menstrual cycle and after light therapy in premenstrual dysphoric disorder and normal control subjects.

PubMed

Parry, B L; Berga, S L; Mostofi, N; Klauber, M R; Resnick, A

1997-02-01

The aim of this study was to replicate and extend previous work in which the authors observed lower, shorter, and advanced nocturnal melatonin secretion patterns in premenstrually depressed patients compared to those in healthy control women. The authors also sought to test the hypothesis that the therapeutic effect of bright light in patients was associated with corrective effects on the phase, duration, and amplitude of melatonin rhythms. In 21 subjects with premenstrual dysphoric disorder (PMDD) and 11 normal control (NC) subjects, the authors measured the circadian profile of melatonin during follicular and luteal menstrual cycle phases and after 1 week of light therapy administered daily, in a randomized crossover design. During three separate luteal phases, the treatments were either (1) bright (> 2,500 lux) white morning (AM; 06:30 to 08:30 h), (2) bright white evening (PM; 19:00 to 21:00 h), or (3) dim (< 10 lux) red evening light (RED). In PMDD subjects, during the luteal phase compared to the follicular menstrual cycle phase, melatonin onset time was delayed, duration was compressed, and area under the curve, amplitude, and mean levels were decreased. In NC subjects, melatonin rhythms did not change significantly during the menstrual cycle. After AM light in PMDD subjects, onset and offset times were advanced and both duration and midpoint concentration were decreased as compared to RED light. After PM light in PMDD subjects, onset and offset times were delayed, midpoint concentration was increased, and duration was decreased as compared to RED light. By contrast, after light therapy in NC subjects, duration did not change; onset, offset, and midpoint concentration changed as they did in PMDD subjects. When the magnitude of advance and delay phase shifts in onset versus offset time with AM, PM, or RED light were compared, the authors found that in PMDD subjects light shifted offset time more than onset time and that AM light had a greater effect on shifting melatonin offset time (measured the following night in RED light), whereas PM light had a greater effect in shifting melatonin onset time. These findings replicate the authors' previous observation that nocturnal melatonin concentrations are decreased in women with PMDD and suggest specific effects of light therapy on melatonin circadian rhythms that are associated with mood changes in patient versus control groups. The differential changes in onset and offset times during the menstrual cycle, and in response to AM and PM bright light compared with RED light, support a two-oscillator (complex) model of melatonin regulation in humans.

Plant hormone signaling lightens up: integrators of light and hormones.

PubMed

Lau, On Sun; Deng, Xing Wang

2010-10-01

Light is an important environmental signal that regulates diverse growth and developmental processes in plants. In these light-regulated processes, multiple hormonal pathways are often modulated by light to mediate the developmental changes. Conversely, hormone levels in plants also serve as endogenous cues in influencing light responsiveness. Although interactions between light and hormone signaling pathways have long been observed, recent studies have advanced our understanding by identifying signaling integrators that connect the pathways. These integrators, namely PHYTOCHROME-INTERACTING FACTOR 3 (PIF3), PIF4, PIF3-LIKE 5 (PIL5)/PIF1 and LONG HYPOCOTYL 5 (HY5), are key light signaling components and they link light signals to the signaling of phytohormones, such as gibberellin (GA), abscisic acid (ABA), auxin and cytokinin, in regulating seedling photomorphogenesis and seed germination. This review focuses on these integrators in illustrating how light and hormone interact. Copyright © 2010 Elsevier Ltd. All rights reserved.

Low level light promotes the proliferation and differentiation of bone marrow derived mesenchymal stem cells

NASA Astrophysics Data System (ADS)

Ahn, Jin-Chul; Rhee, Yun-Hee; Choi, Sun-Hyang; Kim, Dae Yu; Chung, Phil-Sang

2015-03-01

Low-level light irradiation (LLLI) reported to stimulate the proliferation or differentiation of a variety of cell types. However, very little is known about the effect of light therapy on stem cells. The aim of the present study was to evaluate the effect of LLLI on the molecular physiological change of human bone marrow derived stem cells (hBMSC) by wavelength (470, 630, 660, 740 and 850, 50mW). The laser diode was performed with different time interval (0, 7.5, 15, 30J/cm2, 50mW) on hBMSC. To determine the molecular physiological changes of cellular level of hBMSC, the clonogenic assay, ATP assay, reactive oxygen species (ROS) detection, mitochondria membrane potential (MMPΦ) staining and calcium efflux assay were assessed after irradiation. There was a difference between with and without irradiation on hBMSCs. An energy density up to 30 J/cm² improved the cell proliferation in comparison to the control group. Among these irradiated group, 630 and 660nm were significantly increased the cell proliferation. The cellular level of ATP and calcium influx was increased with energy dose-dependent in all LLLI groups. Meanwhile, ROS and MMPΦ were also increased after irradiation except 470nm. It can be concluded that LLLI using infrared light and an energy density up to 30 J/cm² has a positive stimulatory effect on the proliferation or differentiation of hBMSCs. Our results suggest that LLLI may influence to the mitochondrial membrane potential activity through ATP synthesis and increased cell metabolism which leads to cell proliferation and differentiation.

Photosynthate partitioning to starch in Arabidopsis thaliana is insensitive to light intensity but sensitive to photoperiod due to a restriction on growth in the light in short photoperiods.

PubMed

Mengin, Virginie; Pyl, Eva-Theresa; Alexandre Moraes, Thiago; Sulpice, Ronan; Krohn, Nicole; Encke, Beatrice; Stitt, Mark

2017-11-01

Photoperiod duration can be predicted from previous days, but irradiance fluctuates in an unpredictable manner. To investigate how allocation to starch responds to changes in these two environmental variables, Arabidopsis Col-0 was grown in a 6 h and a 12 h photoperiod at three different irradiances. The absolute rate of starch accumulation increased when photoperiod duration was shortened and when irradiance was increased. The proportion of photosynthate allocated to starch increased strongly when photoperiod duration was decreased but only slightly when irradiance was decreased. There was a small increase in the daytime level of sucrose and twofold increases in glucose, fructose and glucose 6-phosphate at a given irradiance in short photoperiods compared to long photoperiods. The rate of starch accumulation correlated strongly with sucrose and glucose levels in the light, irrespective of whether these sugars were responding to a change in photoperiod or irradiance. Whole plant carbon budget modelling revealed a selective restriction of growth in the light period in short photoperiods. It is proposed that photoperiod sensing, possibly related to the duration of the night, restricts growth in the light period in short photoperiods, increasing allocation to starch and providing more carbon reserves to support metabolism and growth in the long night. © 2017 John Wiley & Sons Ltd.

Lower light intensity reduces larval aggression in matrinxã, Brycon amazonicus.

PubMed

Lopes, Ana Caroliny C; Villacorta-Correa, Marle Angélica; Carvalho, Thaís B

2018-06-01

Brycon amazonicus shows a high frequency of aggressive behavior, which can be a limiting factor in intensive farming systems. Environmental changes can modulate the social interactions of fish and reduce aggression during the different stages of production. Groups of three larvae at 12 h after hatching (HAH) were subjected to different levels of light intensity: low (17 ± 3 lx), intermediate (204 ± 12.17 lx) and high (1,613.33 ± 499.03 lx), with eight replicates for each level. The lower light intensity reduced the frequency of aggressive interactions and locomotor activity exhibited by the animals. Based on these results, light intensity modulates aggression in B. amazonicus larvae. Manipulation of this factor could improve the social conditions of this species during farming and contribute to the development of new production technologies. Copyright © 2018 Elsevier B.V. All rights reserved.

Analysis of gas exchange, stomatal behaviour and micronutrients uncovers dynamic response and adaptation of tomato plants to monochromatic light treatments.

PubMed

O'Carrigan, Andrew; Babla, Mohammad; Wang, Feifei; Liu, Xiaohui; Mak, Michelle; Thomas, Richard; Bellotti, Bill; Chen, Zhong-Hua

2014-09-01

Light spectrum affects the yield and quality of greenhouse tomato, especially over a prolonged period of monochromatic light treatments. Physiological and chemical analysis was employed to investigate the influence of light spectral (blue, green and red) changes on growth, photosynthesis, stomatal behaviour, leaf pigment, and micronutrient levels. We found that plants are less affected under blue light treatment, which was evident by the maintenance of higher A, gs, Tr, and stomatal parameters and significantly lower VPD and Tleaf as compared to those plants grown in green and red light treatments. Green and red light treatments led to significantly larger increase in the accumulation of Fe, B, Zn, and Cu than blue light. Moreover, guard cell length, width, and volume all showed highly significant positive correlations to gs, Tr and negative links to VPD. There was negative impact of monochromatic lights-induced accumulation of Mn, Cu, and Zn on photosynthesis, leaf pigments and plant growth. Furthermore, most of the light-induced significant changes of the physiological traits were partially recovered at the end of experiment. A high degree of morphological and physiological plasticity to blue, green and red light treatments suggested that tomato plants may have developed mechanisms to adapt to the light treatments. Thus, understanding the optimization of light spectrum for photosynthesis and growth is one of the key components for greenhouse tomato production. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Current state and future perspectives on coupled ice-sheet - sea-level modelling

NASA Astrophysics Data System (ADS)

de Boer, Bas; Stocchi, Paolo; Whitehouse, Pippa L.; van de Wal, Roderik S. W.

2017-08-01

The interaction between ice-sheet growth and retreat and sea-level change has been an established field of research for many years. However, recent advances in numerical modelling have shed new light on the precise interaction of marine ice sheets with the change in near-field sea level, and the related stability of the grounding line position. Studies using fully coupled ice-sheet - sea-level models have shown that accounting for gravitationally self-consistent sea-level change will act to slow down the retreat and advance of marine ice-sheet grounding lines. Moreover, by simultaneously solving the 'sea-level equation' and modelling ice-sheet flow, coupled models provide a global field of relative sea-level change that is consistent with dynamic changes in ice-sheet extent. In this paper we present an overview of recent advances, possible caveats, methodologies and challenges involved in coupled ice-sheet - sea-level modelling. We conclude by presenting a first-order comparison between a suite of relative sea-level data and output from a coupled ice-sheet - sea-level model.

Optical fiber-mediated photosynthesis for enhanced subsurface oxygen delivery.

PubMed

Lanzarini-Lopes, Mariana; Delgado, Anca G; Guo, Yuanming; Dahlen, Paul; Westerhoff, Paul

2018-03-01

Remediation of polluted groundwater often requires oxygen delivery into subsurface to sustain aerobic bacteria. Air sparging or injection of oxygen containing solutions (e.g., hydrogen peroxide) into the subsurface are common. In this study visible light was delivered into the subsurface using radially emitting optical fibers. Phototrophic organisms grew near the optical fiber in a saturated sand column. When applying light in on-off cycles, dissolved oxygen (DO) varied from super saturation levels of >15 mg DO/L in presence of light to under-saturation (<5 mg DO/L) in absence of light. Non-photosynthetic bacteria dominated at longer radial distances from the fiber, presumably supported by soluble microbial products produced by the photosynthetic microorganisms. The dissolved oxygen variations alter redox condition changes in response to light demonstrate the potential to biologically deliver oxygen into the subsurface and support a diverse microbial community. The ability to deliver oxygen and modulate redox conditions on diurnal cycles using solar light may provide a sustainable, long term strategy for increasing dissolved oxygen levels in subsurface environments and maintaining diverse biological communities. Copyright © 2017 Elsevier Ltd. All rights reserved.

Citrullus colocynthis NAC transcription factors CcNAC1 and CcNAC2 are involved in light and auxin signaling.

PubMed

Wang, Zhuoyu; Rashotte, Aaron M; Dane, Fenny

2014-10-01

Two novel NAC transcription factors from C itrullus colocynthis implicated in light and auxin signaling pathway. NAC transcription factors (NAM, ATAF1, 2, CUC2) have multiple functions in plant growth and development. Two NACs, CcNAC1 and CcNAC2, were recently identified in the highly drought-tolerant cucurbit species, Citrullus colocynthis. This study examines the functional role of these genes under different qualities of light based on the in silico analysis of the CcNAC1 and CcNAC2 promoters that revealed the presence of several light-associated motifs. The impact of both light and auxin on CcNAC1 and CcNAC2 expression was examined in C. colocynthis leaves, and using reporter (pCcNAC1, 2::GUS) lines in Arabidopsis. Furthermore, the effects of constitutive overexpression (OE-CcNAC1, 2) in Arabidopsis were also examined under a range of conditions to confirm reporter line linkages. White, blue, red, and far-red light treatments resulted in similar patterns of quantitative changes in CcNAC1and CcNAC2 expression in both species, with the highest transcript increases following red light. Photomorphogenic changes in Arabidopsis hypocotyls were correlated with gene transcript levels. In the absence of light, hypocotyls of OE-CcNAC1/CcNAC2 lines were significantly longer as compared to WT. The addition of exogenous auxin (+IAA) to growth medium also resulted in changes to the hypocotyl lengths of overexpression lines and spatiotemporal reporter line changes in seedlings. Our data suggest that CcNAC1, 2 might be functionally important in the light signaling pathway, and appear connected to the hormone auxin. This is the first study to indicate that NAC genes might play a role in both light and auxin signaling pathways.

Molecular mechanisms of continuous light inhibition of Atlantic salmon parr-smolt transformation

USGS Publications Warehouse

Stefansson, S.O.; Nilsen, Tom O.; Ebbesson, Lars O.E.; Wargelius, A.; Madsen, Steffen S.; Bjornsson, B. Th; McCormick, S.D.

2007-01-01

Atlantic salmon (Salmo salar) rely on changes in photoperiod for the synchronization of the developmental events constituting the parr-smolt transformation. In the absence of photoperiod cues, parr-smolt transformation is incomplete, and such 'pseudo-smolts' normally fail to adapt to seawater. The present study addresses the endocrine and molecular mechanisms controlling the development of hypo-osmoregulatory ability and how artificial photoperiod can disrupt these changes. Juvenile Atlantic salmon reared under constant light (LL) from first feeding, were separated into two groups, and exposed to either LL or simulated natural photoperiod (LDN) from October, eight months prior to the expected completion of smoltification. Juveniles reared on LL grew well, but failed to show the smolt-related reduction in condition factor in spring. Gill mRNA levels of Na+, K+-ATPase (NKA) isoform ??1a decreased in LDN fish through completion of parr-smolt transformation, while levels remained unchanged in the LL group. In contrast, ??1b expression increased 6-fold in the LDN group between February and May, again with no change in the LL group. Further, Na+, K+, 2Cl- co-transporter (NKCC) showed a transient increase in expression in smolts on LDN between February and May, while no changes in mRNA levels were seen in juveniles under LL. Consequently, gill NKA activity and NKA ?? and NKCC protein abundance were significantly lower in juveniles on LL than in smolts on LDN. LL fish in spring had lower circulating levels of thyroid hormones (THs), growth hormone (GH) and cortisol. Gill GH-receptor mRNA levels, determined by quantitative PCR, were less than 50% of controls. In contrast, circulating levels of IGF-1 and gill IGF-1 receptor expression, were comparable to controls. Our findings show that continuous light prevents the completion of parr-smolt transformation at a very basic level, disrupting the natural up-regulation of key elements of the endocrine system involved in the regulation of the parr-smolt transformation, and consequently inhibiting the smoltification-related increase in expression, abundance and activity of gill ion transport proteins. ?? 2007 Elsevier B.V. All rights reserved.

Role of inositol 1,4,5-triphosphate signalling in gravitropic and phototropic gene expression.

PubMed

Salinas-Mondragon, Raul E; Kajla, Jyoti D; Perera, Imara Y; Brown, Christopher S; Sederoff, Heike Winter

2010-12-01

Plants sense light and gravity to orient their direction of growth. One common component in the early events of both phototropic and gravitropic signal transduction is activation of phospholipase C (PLC), which leads to an increase in inositol 1,4,5-triphosphate (InsP(3)) levels. The InsP(3) signal is terminated by hydrolysis of InsP(3) through inositolpolyphosphate-5-phosphatases (InsP 5-ptases). Arabidopsis plants expressing a heterologous InsP 5-ptase have low basal InsP(3) levels and exhibit reduced gravitropic and phototropic bending. Downstream effects of InsP(3)-mediated signalling are not understood. We used comparative transcript profiling to characterize gene expression changes in gravity- or light-stimulated Arabidopsis root apices that were manipulated in their InsP(3) metabolism either through inhibition of PLC activity or expression of InsP 5-ptase. We identified InsP(3)-dependent and InsP(3)-independent co-regulated gene sets in response to gravity or light stimulation. Inhibition of PLC activity in wild-type plants caused similar changes in transcript abundance in response to gravitropic and phototropic stimulation as in the transgenic lines. Therefore, we conclude that changes in gene expression in response to gravitropic and phototropic stimulation are mediated by two signal transduction pathways that vary in their dependence on changes in InsP(3). © 2010 Blackwell Publishing Ltd.

Light-dependent changes in the leaflet movement rhythm of the plant Desmodium gyrans.

PubMed

Sharma, Vijay Kumar; Bardal, Tom Kristian; Johnsson, Anders

2003-01-01

The movements of the lateral leaflets of the Indian telegraph plant Desmodium gyrans (L. F.) DC, have earlier been studied in detail with regards to the effects of chemicals, DC currents, and static magnetic fields. In the present paper we have discussed the oscillation of the lateral leaflets under the influence of white light of various light levels (0-75 micromol x m(-2) x s(-1)), produced by an array of LEDs (light emitting diodes). LEDs were used in contrast to fluorescense tubes as in earlier studies in order to minimize changes of wavelength when light intensity was decreased or increased. Furthermore, care was taken to ensure that the temperature in the experimental chamber was constant. When the oscillations were first monitored in bright light, the oscillations were found to be very rapid and with decreasing light intensity the oscillations slowed down. For light levels lower than about 20 micromol x m(-2) x s(-1) the period of the oscillation of the lateral leaflets was almost constant (or even decreased slightly towards complete darkness). We also show that the oscillations could completely stop under prolonged darkness (for longer than about 6 h) and that such halted oscillations could be restarted in most of the leaflets when he light was turned back on. Such stopping of the oscillation of the lateral leaflets in prolonged darkness suggests that these short period oscillations of the lateral leaflets could have a daily component and in natural environment these oscillations could serve the purpose of optimising the amount of light falling on the leaflets or/and facilitating transpiration of water through stomata. Such a finding could have an implication for the answer to the long standing question of adaptive significance of short period oscillation of the Indian telegraph plant Desmodium gyrans (L. F.) DC.

Mechanisms and fitness implications of photomorphogenesis during chromatic acclimation in cyanobacteria.

PubMed

Montgomery, Beronda L

2016-07-01

Photosynthetic organisms absorb photons and convert light energy to chemical energy through the process of photosynthesis. Photosynthetic efficiency is tuned in response to the availability of light, carbon dioxide and nutrients to promote maximal levels of carbon fixation, while simultaneously limiting the potential for light-associated damage or phototoxicity. Given the central dependence on light for energy production, photosynthetic organisms possess abilities to tune their growth, development and metabolism to external light cues in the process of photomorphogenesis. Photosynthetic organisms perceive light intensity and distinct wavelengths or colors of light to promote organismal acclimation. Cyanobacteria are oxygenic photosynthetic prokaryotes that exhibit abilities to alter specific aspects of growth, including photosynthetic pigment composition and morphology, in responses to changes in available wavelengths and intensity of light. This form of photomorphogenesis is known as chromatic acclimation and has been widely studied. Recent insights into the photosensory photoreceptors found in cyanobacteria and developments in our understanding of the molecular mechanisms initiated by light sensing to affect the changes characteristic of chromatic acclimation are discussed. I consider cyanobacterial responses to light, the broad diversity of photoreceptors encoded by these organisms, specific mechanisms of photomorphogenesis, and associated fitness implications in chromatically acclimating cyanobacteria. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Effects of light on the largest extant benthic foraminifer, Cycloclypeus carpenteri

NASA Astrophysics Data System (ADS)

Fujita, Kazuhiko; Kanda, Yoji

2015-04-01

Cycloclypeus carpenteri is the largest extant benthic foraminifer. This species dwells in deep euphotic depths of warm oligotrophic waters, and is a host to diatom endosymbionts. Fossil Cycloclypeus has been found in tropical shelf carbonates since the Oligocene. Light is supposed to be the primary environmental factor controlling the depth distribution of this species. However, physiological responses of this foraminifer to light are not yet well understood. We investigated short-term and long-term effects of light on Cycloclypeus carpenteri collected from about 70 m depth, west of Okinawa Island (Japan). To determine short-term responses to light, net oxygen production was measured at different light levels and wavelengths using an oxygen microelectrode. Photosynthesis-irradiance curve of this species indicated that net oxygen production increased up to 50 µE m-2 s-1, was saturated until 100 µE m-2 s-1, then was photoinhibited over 100 µE m-2 s-1. Net production was higher when incubated on blue wavelength than on either red or green wavelengths. To determine long-term light effects, asexually reproduced clone individuals were incubated for about 4 months at different light levels ranging from 0 to 100 µE m-2 s-1. The long-term incubations indicated that growth rates measured by the surface area were optimal at light levels from 5 to 50 µE m-2 s-1, but were lowered at 0 and 100 µE m-2 s-1. These results suggest that Cycloclypeus carpenteri can be acclimatized at less than 100 µE m-2 s-1 of light by changing photopigment (chrolophyll) concentrations of algal symbionts, but this species cannot survive in dark and over 100 µE m-2 s-1 of light due to the breakdown of algal symbiosis.

The effect of reduced street lighting on road casualties and crime in England and Wales: controlled interrupted time series analysis

PubMed Central

Steinbach, Rebecca; Perkins, Chloe; Tompson, Lisa; Johnson, Shane; Armstrong, Ben; Green, Judith; Grundy, Chris; Wilkinson, Paul

2015-01-01

Background Many local authorities in England and Wales have reduced street lighting at night to save money and reduce carbon emissions. There is no evidence to date on whether these reductions impact on public health. We quantified the effect of 4 street lighting adaptation strategies (switch off, part-night lighting, dimming and white light) on casualties and crime in England and Wales. Methods Observational study based on analysis of geographically coded police data on road traffic collisions and crime in 62 local authorities. Conditional Poisson models were used to analyse longitudinal changes in the counts of night-time collisions occurring on affected roads during 2000–2013, and crime within census Middle Super Output Areas during 2010–2013. Effect estimates were adjusted for regional temporal trends in casualties and crime. Results There was no evidence that any street lighting adaptation strategy was associated with a change in collisions at night. There was significant statistical heterogeneity in the effects on crime estimated at police force level. Overall, there was no evidence for an association between the aggregate count of crime and switch off (RR 0.11; 95% CI 0.01 to 2.75) or part-night lighting (RR 0.96; 95% CI 0.86 to 1.06). There was weak evidence for a reduction in the aggregate count of crime and dimming (RR 0.84; 95% CI 0.70 to 1.02) and white light (RR 0.89; 95% CI 0.77 to 1.03). Conclusions This study found little evidence of harmful effects of switch off, part-night lighting, dimming, or changes to white light/LEDs on road collisions or crime in England and Wales. PMID:26219885

Changes in Energy Intake and Diet Quality during an 18-Month Weight-Management Randomized Controlled Trial in Adults with Intellectual and Developmental Disabilities.

PubMed

Ptomey, Lauren T; Steger, Felicia L; Lee, Jaehoon; Sullivan, Debra K; Goetz, Jeannine R; Honas, Jeffery J; Washburn, Richard A; Gibson, Cheryl A; Donnelly, Joseph E

2018-06-01

Previous research indicates that individuals with intellectual and developmental disabilities (IDDs) are at risk for poor diet quality. The purpose of this secondary analysis was to determine whether two different weight-loss diets affect energy intake, macronutrient intake, and diet quality as measured by the Healthy Eating Index-2010 (HEI-2010) during a 6-month weight-loss period and 12-month weight-management period, and to examine differences in energy intake, macronutrient intake, and HEI-2010 between groups. Overweight/obese adults with IDDs took part in an 18-month randomized controlled trial and were assigned to either an enhanced Stop Light Diet utilizing portion-controlled meals or a conventional diet consisting of reducing energy intake and following the 2010 Dietary Guidelines for Americans. Proxy-assisted 3-day food records were collected at baseline, 6 months, and 18 months, and were analyzed using Nutrition Data System for Research software. HEI-2010 was calculated using the data from Nutrition Data System for Research. The study took place from June 2011 through May 2014 in the greater Kansas City metropolitan area. This was a secondary analysis of a weight-management intervention for adults with IDDs randomized to an enhanced Stop Light Diet or conventional diet, to examine differences in energy intake, macronutrient intake, and HEI-2010 across time and between groups. Independent- and paired-samples t tests and general mixed modeling for repeated measures were performed to examine group differences and changes at baseline, 6 months, and 18 months between the enhanced Stop Light Diet and conventional diet groups. One hundred and forty six participants (57% female, mean±standard deviation age=36.2±12.0 years) were randomized to either the enhanced Stop Light Diet or conventional diet group (77 enhanced Stop Light Diet, 69 conventional diet) and provided data for analysis at baseline, 124 completed the 6-month weight-loss period, and 101 completed the 18-month study. Participants on the enhanced Stop Light Diet diet significantly reduced energy intake at 6 and 18 months (both P<0.001), but those on the conventional diet did not (both P=0.13). However, when accounting for age, sex, race, education level, and support level (mild vs moderate IDD), there was a significant decrease during the 18-month intervention in energy intake for the enhanced Stop Light Diet and conventional diet groups combined (P<0.01 for time effect), but no significant group difference in this change (P=0.39 for group-by-time interaction). There was no significant change in total HEI-2010 score at 6 and 18 months (P=0.05 and P=0.38 for the enhanced Stop Light Diet group; P=0.22 and P=0.17 for the conventional diet group), and no significant group difference at 6 and 18 months (P=0.08 and P=0.42). However, when participants' age, sex, race, education level, and support level were accounted for, mixed modeling indicated a significant increase in total HEI-2010 scores for the enhanced Stop Light Diet and conventional diet groups combined during the 18-month intervention (P=0.01 for time effect). The results of this study found that after controlling for demographic factors, individuals with IDDs can decrease their energy intake and increase their diet quality, with no significant differences between the enhanced Stop Light Diet and conventional diet groups. Copyright © 2018 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

Lactate in the brain of the freely moving rat: voltammetric monitoring of the changes related to the sleep-wake states.

PubMed

Shram, Nataliya; Netchiporouk, Larissa; Cespuglio, Raymond

2002-08-01

Cortical lactate was monitored voltammetrically in freely moving rats equipped with polygraphic electrodes. Differential normal pulse voltammetric measurements were carried out using a lactate biosensor coated with lactate oxidase and cellulose acetate. Changes occurring in lactate level were in keeping with sleep-wake states. During slow wave sleep (SWS), the lactate level decreased significantly (-16.2%) vs. the spontaneous waking state (W) referenced to as 100%. During paradoxical sleep (PS), and still vs. W, it remained low (-9.0%) but this variation was not statistically significant. However, when this PS change was compared to the SWS variation, a significant increase in lactate level was then revealed (+8.5%). Finally, during the active waking (aW) triggered by a water puff stress, lactate level rose significantly in accordance with the animal activity (+53% compared to W). Long-term monitoring also allowed the determination of a circadian component in lactate production, the lowest and highest values being monitored during light and dark periods, respectively. The acrophasis of the circadian change occurred during the dark period, about 3 h after the light-off (+89%). It is suggested that during wakefulness astrocyte metabolism allows the transformation of the blood-borne glucose into lactate. The increase in this substrate observed during PS may fulfil the oxidative phosphorylation in order to supply the important ATP need of PS.

A computer-aided diagnosis system to detect pathologies in temporal subtraction images of chest radiographs

NASA Astrophysics Data System (ADS)

Looper, Jared; Harrison, Melanie; Armato, Samuel G.

2016-03-01

Radiologists often compare sequential radiographs to identify areas of pathologic change; however, this process is prone to error, as human anatomy can obscure the regions of change, causing the radiologists to overlook pathology. Temporal subtraction (TS) images can provide enhanced visualization of regions of change in sequential radiographs and allow radiologists to better detect areas of change in radiographs. Not all areas of change shown in TS images, however, are actual pathology. The purpose of this study was to create a computer-aided diagnostic (CAD) system that identifies which regions of change are caused by pathology and which are caused by misregistration of the radiographs used to create the TS image. The dataset used in this study contained 120 images with 74 pathologic regions on 54 images outlined by an experienced radiologist. High and low ("light" and "dark") gray-level candidate regions were extracted from the images using gray-level thresholding. Then, sampling techniques were used to address the class imbalance problem between "true" and "false" candidate regions. Next, the datasets of light candidate regions, dark candidate regions, and the combined set of light and dark candidate regions were used as training and testing data for classifiers by using five-fold cross validation. Of the classifiers tested (support vector machines, discriminant analyses, logistic regression, and k-nearest neighbors), the support vector machine on the combined candidates using synthetic minority oversampling technique (SMOTE) performed best with an area under the receiver operating characteristic curve value of 0.85, a sensitivity of 85%, and a specificity of 84%.

Fiber optic moisture sensor with moisture-absorbing reflective target

DOEpatents

Kirkham, Randy R.

1987-01-01

A method and apparatus for sensing moisture changes by utilizing optical fiber technology. One embodiment uses a reflective target at the end of an optical fiber. The reflectance of the target varies with its moisture content and can be detected by a remote unit at the opposite end of the fiber. A second embodiment utilizes changes in light loss along the fiber length. This can be attributed to changes in reflectance of cladding material as a function of its moisture content. It can also be affected by holes or inserts interposed in the cladding material and/or fiber. Changing light levels can also be coupled from one fiber to another in an assembly of fibers as a function of varying moisture content in their overlapping lengths of cladding material.

Non-invasive method to detect the changes of glucose concentration in whole blood using photometric technique.

PubMed

Rajan, Shiny Amala Priya; Towe, Bruce C

2014-01-01

A non-invasive method is developed to monitor rapid changes in blood glucose levels in diabetic patients. The system depends on an optical cell built with a LED that emits light of wavelength 535nm, which is a peak absorbance of hemoglobin. As the glucose concentration in blood decreases, its osmolarity also decreases and the Red Blood Cells (RBCs) swell and decrease the path length absorption coefficient. Decreasing absorption coefficient increases the transmission of light through the whole blood. The system was tested with a constructed optical cell that held whole blood in a capillary tube. As expected the light transmitted to the photodiode increases with decreasing glucose concentration. The average response time of the system was between 30-40 seconds.

A decision model applied to alcohol effects on driver signal light behavior

NASA Technical Reports Server (NTRS)

Schwartz, S. H.; Allen, R. W.

1978-01-01

A decision model including perceptual noise or inconsistency is developed from expected value theory to explain driver stop and go decisions at signaled intersections. The model is applied to behavior in a car simulation and instrumented vehicle. Objective and subjective changes in driver decision making were measured with changes in blood alcohol concentration (BAC). Treatment levels averaged 0.00, 0.10 and 0.14 BAC for a total of 26 male subjects. Data were taken for drivers approaching signal lights at three timing configurations. The correlation between model predictions and behavior was highly significant. In contrast to previous research, analysis indicates that increased BAC results in increased perceptual inconsistency, which is the primary cause of increased risk taking at low probability of success signal lights.

a Study of the Bioluminescence of Larger Zooplankton and the Effects of Low-Level Light Changes on Their Behavior.

NASA Astrophysics Data System (ADS)

van Keuren, Jeffrey Robert

A bio-optical study was undertaken to quantify the relationships which exist between counter-illuminating organisms and the downwelling spectral light field in which they exist. The basic hypothesis behind counter-illumination is that the animal emits light using ventrally-oriented photophores to disrupt or eliminate the shadowed area on ventral surfaces. An organism lacking photophores sharply silhouettes against the highly directional downwelling irradiance, whereas by distributing photophores over the ventral surface of the body and closely matching the spectral and intensity characteristics of the downwelling light, this silhouette is obscured. Analysis carried out on changes in vertical distribution patterns in response to low-level intensity changes in ambient surface light suggested that diel migrating organisms begin to shift vertically in the water column when surface scalar irradiance decreased below or increased above 1.0 times10^{-2} muEin m^{-2} sec^ {-1}. Maximum aggregations of organisms, as defined by MOCNESS net sampling or single-frequency acoustic backscatter, appeared to remain within definable in situ blue-green isolume ranges varying less than a factor of ten throughout each night. Comparisons made between organism counter-illumination capacity and modeled in situ downwelling irradiance levels suggested that euphausiids, decapods and myctophids use between 1-10 percent of their maximum counter-illumination capacity to match the ambient downwelling light conditions. Modeling also suggested that up to 40 percent of the maximum measured bioluminescence output is required to match ambient irradiance in the shallower surface zones where aggregations of copepods, potential food sources, were commonly found at night. An optical study to quantify the radiative transfer of bioluminescence from a point source revealed that non -isotropic point sources produce radiance patterns that cannot be simply explained by inverse square losses. Therefore simple inverse-square estimates of bioluminescent propagation loss rates from organisms in the ocean are an oversimplification of the radiative transfer processes that occur when these emissions occur. Additionally, in evaluating counter-illumination, the distance of the receptor, such as the eyes of a potential predator, is critical in determining the effectiveness of the organisms in matching the uniform light field of their surrounding environment and ultimately avoiding detection and predation.

The Martian twilight

NASA Technical Reports Server (NTRS)

Kahn, R.; Goody, R.; Pollack, J.

1981-01-01

The changing sky brightness during the Martian twilight as measured by the Viking lander cameras is shown to be consistent with data obtained from sky brightness measurements. An exponential distribution of dust with a scale height of 10 km, equal to the atmospheric scale height, is consistent with the shape of the light curve. Multiple scattering resulting from the forward scattering peak of large particles makes a major contribution to the intensity of the twilight. The spectral distribution of light in the twilight sky may require slightly different optical properties for the scattering particles at high levels from those of the aerosol at lower levels.

Effects of light conditions and temperature gradients on vertical migration behavior of larval Arctic cod (Boreogadus saida) and walleye pollock (Gadus chalcogramma)

NASA Astrophysics Data System (ADS)

Flanders, K. R.; Laurel, B.

2016-02-01

Early life stages of marine fishes must maximize growth while minimizing vulnerability to predators. Larval stages in particular are subject to ocean currents, but encounter favorable habitats by adjusting their vertical position in the water column. The investigation of environmental cues that change larval fish behavior is therefore crucial to understanding larval drift and dispersal modeling, and subsequently population structure and connectivity. In this study, the behavioral responses of larval Arctic cod (Boreogadus saida) and walleye pollock (Gadus chalcogramma) in a vertical water column were examined. Two prominent environmental variables, light and temperature, were manipulated over 3 h during observational trials. Light intensity was studied at two levels (1.484 x 101 μE m-2 s-1 ; 2.54 x102 μE m-2 s-1), and a diel effect was studied through the removal of light after 2 h. Light intensity did not significantly impact the position of either species in a vertical water column. However, a significant difference by species was apparent when all light levels were considered: the mean position of Arctic cod was closer to the surface of the water than that of walleye pollock. The effect of temperature through the introduction of a thermocline (range 5.6°C - 1.5°C) was limited to walleye pollock given the Arctic cod larvae were surface oriented across all light treatments. However, the thermocline did not significantly impact the relative change in position from light to dark in walleye pollock, likely because they were also surface oriented in control treatments. These results could be incorporated into future larval dispersal and survival models, particularly in Alaskan and Arctic waters, to investigate changes in species distributions resulting from global warming impacts. These results also indicate population structures of Arctic cod and walleye pollock could be affected, which may be reflected in ecosystem and trophic interactions. Because Arctic cod larvae were found to be significantly surface-oriented, rising sea surface temperatures pose a considerable threat while walleye pollock could continue territorial expansion northward.

A qualitative study of consumer perceptions and use of traffic light food labelling in Ecuador.

PubMed

Freire, Wilma B; Waters, William F; Rivas-Mariño, Gabriela; Nguyen, Tien; Rivas, Patricio

2017-04-01

To analyse patterns of knowledge, comprehension, attitudes and practices regarding the traffic light label placed on processed food packages to inform Ecuadorian consumers about levels of added fat, sugar and salt. Twenty-one focus group discussions organized by age group, sex and place of residence. Interviews with representatives of companies that manufacture or market processed foods. Analysis of regulations and structured observations of processed food labels. Cities and towns in Ecuador's coastal, highland and eastern lowland regions. One hundred and seventy-eight participants in twenty-one focus group discussions and nine key informants. Focus group participants knew about the traffic light label and understood the information it conveys, but not all changed their attitudes and practices related to the purchase and consumption of processed foods. Children, adolescents and adult males reported using the information infrequently; adolescents interested in health and adult women used the label the most to select products. Representatives of companies that manufacture or market processed foods generally opposed the policy, stating that the information is misleading. Nevertheless, some companies have reduced levels of added fat, sugar or salt in their products. The traffic light label is an effective tool for conveying complex information. Its potential contribution to reduce consumption of products with high levels of fat, sugar and salt could be enhanced by promoting healthy diets among consumers who have not changed purchasing and consumption behaviour, by placing the label on front panels and by monitoring the production and marketing of processed foods.

Physiological correlates of symbiont migration during bleaching of two octocoral species.

PubMed

Netherton, Sarah E; Scheer, Daniele M; Morrison, Patrick R; Parrin, Austin P; Blackstone, Neil W

2014-05-01

Perturbed colonies of Phenganax parrini and Sarcothelia sp. exhibit migration of symbionts of Symbiodinium spp. into the stolons. Densitometry and visual inspection indicated that polyps bleached while stolons did not. When migration was triggered by temperature, light and confinement, colonies of Sarcothelia sp. decreased rates of oxygen formation in the light (due to the effects of perturbation on photosynthesis and respiration) and increased rates of oxygen uptake in the dark (due to the effects of perturbation on respiration alone). Colonies of P. parrini, by contrast, showed no significant changes in either aspect of oxygen metabolism. When migration was triggered by light and confinement, colonies of Sarcothelia sp. showed decreased rates of oxygen formation in the light and increased rates of oxygen uptake in the dark, while colonies of P. parrini maintained the former and increased the latter. During symbiont migration into their stolons, colonies of both species showed dramatic increases in reactive oxygen species (ROS), as visualized with a fluorescent probe, with stolons of Sarcothelia sp. exhibiting a nearly immediate increase of ROS. Differences in symbiont type may explain the greater sensitivity of colonies of Sarcothelia sp. Using fluorescent probes, direct measurements of migrating symbionts in the stolons of Sarcothelia sp. showed higher levels of reactive nitrogen species and lower levels of ROS than the surrounding host tissue. As measured by native fluorescence, levels of NAD(P)H in the stolons were unaffected by perturbation. Symbiont migration thus correlates with dramatic physiological changes and may serve as a marker for coral condition.

[Spatiotemporal variation of typical red soil eroded landscape pattern: a case study in Changting County of Fujian Province].

PubMed

Wu, Guo-sheng; Lin, Hui-hua; Zhu, He-jian; Sha, Jin-ming; Dai, Wen-yuan

2011-07-01

Based on the 1988, 2000, and 2007 remote sensing images of a typical red soil eroded region (Changting County, Fujian Province) and the digital elevation model (DEM), the eroded landscape types were worked out, and the changes of the eroded landscape pattern in the region from 1988 to 2007 were analyzed with the spatial mathematics model. In 1988-2007, different eroded landscape types in the region had the characteristics of inter-transfer, mainly manifested in the transfer from seriously eroded to lightly eroded types but still existed small amount of the transference from lightly eroded to seriously eroded types. Little change was observed in the controid of the eroded landscape. In the County, Hetian Town was all along the eroded center. During the study period, the landscape pattern index showed a tendency of low heterogeneity, low fragmentation, and high regularization at landscape level, but an overall improvement and expansion of lightly eroded and easy-to-tackle patches as well as the partial improvement and fragmentation of seriously eroded and difficult-to-tackle patches at patch level.

Subtle flickering in Cepheids: Kepler and MOST

NASA Astrophysics Data System (ADS)

Evans, Nancy Remage; Szabó, Robert; Szabados, Laszlo; Derekas, Aliz; Matthews, Jaymie M.; Cameron, Chris; the MOST Team

2014-02-01

Fundamental mode classical Cepheids have light curves which repeat accurately enough that we can watch them evolve (change period). The new level of accuracy and quantity of data with the Kepler and MOST satellites probes this further. An intriguing result was found in the long time-series of Kepler data for V1154 Cyg the one classical Cepheid (fundamental mode, P = 4.9 d) in the field, which has short term changes in period (~=20 minutes), correlated for ~=10 cycles (period jitter). To follow this up, we obtained a month long series of observations of the fundamental mode Cepheid RT Aur and the first overtone pulsator SZ Tau. RT Aur shows the traditional strict repetition of the light curve, with the Fourier amplitude ratio R 1/R 2 remaining nearly constant. The light curve of SZ Tau, on the other hand, fluctuates in amplitude ratio at the level of approximately 50%. Furthermore prewhitening the RT Aur data with 10 frequencies reduces the Fourier spectrum to noise. For SZ Tau, considerable power is left after this prewhitening in a complicated variety of frequencies.

Abscisic acid, xanthoxin and violaxanthin in the caps of gravistimulated maize roots

NASA Technical Reports Server (NTRS)

Feldman, L. J.; Arroyave, N. J.; Sun, P. S.

1985-01-01

The occurrence and distribution of abscisic acid (ABA), xanthoxin (Xa) and the carotenoid violaxanthin (Va) were investigated in root tips of maize (Zea mays L. cv. Merit). In roots grown in the dark, Va and ABA were present in relatively high amounts in the root cap and in low amounts in the adjacent terminal 1.5 mm of the root. Xanthoxin was present in equal concentrations in both regions. In roots exposed to light, the ABA distribution was reversed, with relatively low levels in the root cap and high levels in the adjacent 1.5-mm segment. Light also caused a decrease in Va in both regions of the root and an increase in Xa, especially in the cap. In the maize cultivar used for this work, light is necessary for gravitropic curving. This response occurs within the same time frame as the light-induced ABA redistribution as well as the changes in the levels of Va and Xa. These data are consistent with a role for ABA in root gravitropism and support the proposal that Xa may arise from the turnover of Va.

Light represses transcription of asparagine synthetase genes in photosynthetic and nonphotosynthetic organs of plants.

PubMed Central

Tsai, F Y; Coruzzi, G

1991-01-01

Asparagine synthetase (AS) mRNA in Pisum sativum accumulates preferentially in plants grown in the dark. Nuclear run-on experiments demonstrate that expression of both the AS1 and AS2 genes is negatively regulated by light at the level of transcription. A decrease in the transcriptional rate of the AS1 gene can be detected as early as 20 min after exposure to light. Time course experiments reveal that the levels of AS mRNA fluctuate dramatically during a "normal" light/dark cycle. This is due to a direct effect of light and not to changes associated with circadian rhythm. A novel finding is that the light-repressed expression of the AS1 gene is as dramatic in nonphotosynthetic organs such as roots as it is in leaves. Experiments demonstrate that the small amount of light which passes through the soil is sufficient to repress AS1 expression in roots, indicating that light has a direct effect on AS1 gene expression in roots. The negative regulation of AS gene expression by light was shown to be a general phenomenon in plants which also occurs in nonlegumes such as Nicotiana plumbaginifolia and Nicotiana tabacum. Thus, the AS genes can serve as a model with which to dissect the molecular basis for light-regulated transcriptional repression in plants. Images PMID:1681424

Dopamine D1 receptor activation contributes to light-adapted changes in retinal inhibition to rod bipolar cells.

PubMed

Flood, Michael Daniel; Moore-Dotson, Johnnie M; Eggers, Erika D

2018-05-30

Dopamine modulation of retinal signaling has been shown to be an important part of retinal adaptation to increased background light levels but the role of dopamine modulation of retinal inhibition is not clear. We previously showed that light adaptation causes a large reduction in inhibition to rod bipolar cells, potentially to match the decrease in excitation after rod saturation. In this study we determined how dopamine D1 receptors in the inner retina contribute to this modulation. We found that D1 receptor activation significantly decreased the magnitude of inhibitory light responses from rod bipolar cells, while D1 receptor blockade during light adaptation partially prevented this decline. To determine what mechanisms were involved in the modulation of inhibitory light responses, we measured the effect of D1 receptor activation on spontaneous currents and currents evoked from electrically stimulating amacrine cell inputs to rod bipolar cells. D1 receptor activation decreased the frequency of spontaneous inhibition with no change in event amplitudes, suggesting a presynaptic change in amacrine cell activity in agreement with previous reports that rod bipolar cells lack D1 receptors. Additionally, we found that D1 receptor activation reduced the amplitude of electrically-evoked responses, showing that D1 receptors can modulate amacrine cells directly. Our results suggest that D1 receptor activation can replicate a large portion, but not all of the effects of light adaptation, likely by modulating release from amacrine cells onto rod bipolar cells.

The 2011 June 23 Stellar Occultation by Pluto: Airborne and Ground Observations

NASA Astrophysics Data System (ADS)

Person, M. J.; Dunham, E. W.; Bosh, A. S.; Levine, S. E.; Gulbis, A. A. S.; Zangari, A. M.; Zuluaga, C. A.; Pasachoff, J. M.; Babcock, B. A.; Pandey, S.; Amrhein, D.; Sallum, S.; Tholen, D. J.; Collins, P.; Bida, T.; Taylor, B.; Bright, L.; Wolf, J.; Meyer, A.; Pfueller, E.; Wiedemann, M.; Roeser, H.-P.; Lucas, R.; Kakkala, M.; Ciotti, J.; Plunkett, S.; Hiraoka, N.; Best, W.; Pilger, E. J.; Micheli, M.; Springmann, A.; Hicks, M.; Thackeray, B.; Emery, J. P.; Tilleman, T.; Harris, H.; Sheppard, S.; Rapoport, S.; Ritchie, I.; Pearson, M.; Mattingly, A.; Brimacombe, J.; Gault, D.; Jones, R.; Nolthenius, R.; Broughton, J.; Barry, T.

2013-10-01

On 2011 June 23, stellar occultations by both Pluto (this work) and Charon (future analysis) were observed from numerous ground stations as well as the Stratospheric Observatory for Infrared Astronomy (SOFIA). This first airborne occultation observation since 1995 with the Kuiper Airborne Observatory resulted in the best occultation chords recorded for the event, in three visible wavelength bands. The data obtained from SOFIA are combined with chords obtained from the ground at the IRTF, the U.S. Naval Observatory Flagstaff Station, and Leeward Community College to give the detailed state of the Pluto-Charon system at the time of the event with a focus on Pluto's atmosphere. The data show a return to the distinct upper and lower atmospheric regions with a knee or kink in the light curve separating them as was observed in 1988, rather than the smoothly transitioning bowl-shaped light curves of recent years. The upper atmosphere is analyzed by fitting a model to all of the light curves, resulting in a half-light radius of 1288 ± 1 km. The lower atmosphere is analyzed using two different methods to provide results under the differing assumptions of particulate haze and a strong thermal gradient as causes for the lower atmospheric diminution of flux. These results are compared with those from past occultations to provide a picture of Pluto's evolving atmosphere. Regardless of which lower atmospheric structure is assumed, results indicate that this part of the atmosphere evolves on short timescales with results changing the light curve structures between 1988 and 2006, and then reverting these changes in 2011 though at significantly higher pressures. Throughout these changes, the upper atmosphere remains remarkably stable in structure, again except for the overall pressure changes. No evidence of onset of atmospheric collapse predicted by frost migration models is seen, and the atmosphere appears to be remaining at a stable pressure level, suggesting it should persist at this full level through New Horizon's flyby in 2015.

THE 2011 JUNE 23 STELLAR OCCULTATION BY PLUTO: AIRBORNE AND GROUND OBSERVATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Person, M. J.; Bosh, A. S.; Levine, S. E.

On 2011 June 23, stellar occultations by both Pluto (this work) and Charon (future analysis) were observed from numerous ground stations as well as the Stratospheric Observatory for Infrared Astronomy (SOFIA). This first airborne occultation observation since 1995 with the Kuiper Airborne Observatory resulted in the best occultation chords recorded for the event, in three visible wavelength bands. The data obtained from SOFIA are combined with chords obtained from the ground at the IRTF, the U.S. Naval Observatory Flagstaff Station, and Leeward Community College to give the detailed state of the Pluto-Charon system at the time of the event withmore » a focus on Pluto's atmosphere. The data show a return to the distinct upper and lower atmospheric regions with a knee or kink in the light curve separating them as was observed in 1988, rather than the smoothly transitioning bowl-shaped light curves of recent years. The upper atmosphere is analyzed by fitting a model to all of the light curves, resulting in a half-light radius of 1288 {+-} 1 km. The lower atmosphere is analyzed using two different methods to provide results under the differing assumptions of particulate haze and a strong thermal gradient as causes for the lower atmospheric diminution of flux. These results are compared with those from past occultations to provide a picture of Pluto's evolving atmosphere. Regardless of which lower atmospheric structure is assumed, results indicate that this part of the atmosphere evolves on short timescales with results changing the light curve structures between 1988 and 2006, and then reverting these changes in 2011 though at significantly higher pressures. Throughout these changes, the upper atmosphere remains remarkably stable in structure, again except for the overall pressure changes. No evidence of onset of atmospheric collapse predicted by frost migration models is seen, and the atmosphere appears to be remaining at a stable pressure level, suggesting it should persist at this full level through New Horizon's flyby in 2015.« less

Radiative Transfer Modeling to Estimate the Impact of CDOM on Light Absorption within Changing Arctic Sea Ice

NASA Astrophysics Data System (ADS)

Carns, R.; Light, B.; Frey, K. E.

2016-12-01

First-year sea ice differs from multi-year sea ice in several ways that can influence its optical properties. It is thinner than multi-year ice, which tends to increase light transmission. Also, first-year ice retains higher brine volumes in comparison to more heavily drained multi-year ice, in isolated pockets and channels. During melt season, patterns of pond formation on first-year sea ice differ from those on multi-year ice. As first-year sea ice comprises an increasingly large fraction of Arctic sea ice, it becomes more important to understand how much sunlight reaches the ecosystems within the ice, and how those changing ecosystems can feed back into the transmission of light. Colored dissolved organic matter (CDOM) and chlorophyll within the ice can absorb light, heating the ice and reducing transmission to the ocean below. Light also encourages algal growth within the ice while degrading CDOM, creating complex feedbacks. We use radiative transfer models to determine the overall effect of colored dissolved organic matter on the light regime within sea ice, both on the overall amount of energy transmitted and on the spectral distribution of energy. Using models allows us to estimate the impact of varying CDOM levels on a wide range of sea ice types, improving our ability to respond to conditions in a rapidly changing Arctic and predict important phenomena such as algal blooms.

Defense Coastal/Estuarine Research Program (DCERP)

DTIC Science & Technology

2007-09-19

area, determined by the North Carolina Division of Coastal Management from 1938 to 1992, and LIDAR data suggests that there is not a strong...spectrometry KBDI Keetch-Byram drought index LCAC landing craft air cushion LIDAR Light Detection and Ranging LTSC Long-Term Shoreline Change LVORI low...that the frequency distribution of marsh elevations relative to mean sea level, determined by analysis of Light Detection and Ranging ( LIDAR ) data, is

Chlorophyll f and chlorophyll d are produced in the cyanobacterium Chlorogloeopsis fritschii when cultured under natural light and near-infrared radiation.

PubMed

Airs, R L; Temperton, B; Sambles, C; Farnham, G; Skill, S C; Llewellyn, C A

2014-10-16

We report production of chlorophyll f and chlorophyll d in the cyanobacterium Chlorogloeopsis fritschii cultured under near-infrared and natural light conditions. C. fritschii produced chlorophyll f and chlorophyll d when cultured under natural light to a high culture density in a 20 L bubble column photobioreactor. In the laboratory, the ratio of chlorophyll f to chlorophyll a changed from 1:15 under near-infrared, to an undetectable level of chlorophyll f under artificial white light. The results provide support that chlorophylls f and d are both red-light inducible chlorophylls in C. fritschii. Copyright © 2014 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Light-induced dynamic structural color by intracellular 3D photonic crystals in brown algae.

PubMed

Lopez-Garcia, Martin; Masters, Nathan; O'Brien, Heath E; Lennon, Joseph; Atkinson, George; Cryan, Martin J; Oulton, Ruth; Whitney, Heather M

2018-04-01

Natural photonic crystals are responsible for strong reflectance at selective wavelengths in different natural systems. We demonstrate that intracellular opal-like photonic crystals formed from lipids within photosynthetic cells produce vivid structural color in the alga Cystoseira tamariscifolia . The reflectance of the opaline vesicles is dynamically responsive to environmental illumination. The structural color is present in low light-adapted samples, whereas higher light levels produce a slow disappearance of the structural color such that it eventually vanishes completely. Once returned to low-light conditions, the color re-emerges. Our results suggest that these complex intracellular natural photonic crystals are responsive to environmental conditions, changing their packing structure reversibly, and have the potential to manipulate light for roles beyond visual signaling.

Motion of glossy objects does not promote separation of lighting and surface colour

PubMed Central

2017-01-01

The surface properties of an object, such as texture, glossiness or colour, provide important cues to its identity. However, the actual visual stimulus received by the eye is determined by both the properties of the object and the illumination. We tested whether operational colour constancy for glossy objects (the ability to distinguish changes in spectral reflectance of the object, from changes in the spectrum of the illumination) was affected by rotational motion of either the object or the light source. The different chromatic and geometric properties of the specular and diffuse reflections provide the basis for this discrimination, and we systematically varied specularity to control the available information. Observers viewed animations of isolated objects undergoing either lighting or surface-based spectral transformations accompanied by motion. By varying the axis of rotation, and surface patterning or geometry, we manipulated: (i) motion-related information about the scene, (ii) relative motion between the surface patterning and the specular reflection of the lighting, and (iii) image disruption caused by this motion. Despite large individual differences in performance with static stimuli, motion manipulations neither improved nor degraded performance. As motion significantly disrupts frame-by-frame low-level image statistics, we infer that operational constancy depends on a high-level scene interpretation, which is maintained in all conditions. PMID:29291113

Changes in light intensity reveal a major role for carbon balance in Arabidopsis responses to high temperature.

PubMed

Vasseur, François; Pantin, Florent; Vile, Denis

2011-09-01

High temperature (HT) is a major limiting factor for plant productivity. Because some responses to HT, notably hyponasty, resemble those encountered in low light (LL), we hypothesized that plant responses to HT are under the control of carbon balance. We analysed the interactive effects of HT and irradiance level on hyponasty and a set of traits related to plant growth in natural accessions of Arabidopsis thaliana and mutants affected in heat dissipation through transpiration (NCED6-OE, ost2) and starch metabolism (pgm). HT induced hyponasty, reduced plant growth and modified leaf structure. LL worsened the effects of HT, while increasing light restored trait values close to levels observed at control temperature. Leaf temperature per se did not play a major role in the observed responses. By contrast, a major role of carbon balance was supported by hyponastic growth of pgm, as well as morphological, physiological (photosynthesis, sugar and starch contents) and transcriptional data. Carbon balance could be a common sensor of HT and LL, leading to responses specific of the shade avoidance syndrome. Hyponasty and associated changes in plant traits could be key traits conditioning plant performance under competition for light, particularly in warm environments. © 2011 Blackwell Publishing Ltd.

The phototoxicity of phenothiazinium-based photosensitizers to bacterial membranes.

PubMed

Hussain, Saimah; Harris, Frederick; Phoenix, David A

2006-02-01

The ability of phenothiazinium-based photosensitizers to induce photodamage to Escherichia coli membranes is investigated. Phenothiazinium-based photosensitizers were found to be somewhat lipophilic (log P>0.7) and to induce surface-pressure changes (3-12 mN m(-1)) in lipid monolayers mimetic of bacterial membranes, implying that these molecules are able to penetrate biological membranes. Under dark and light conditions (3.15 J cm(-1) for 30 min), phenothiazinium-based photosensitizers were incubated with E. coli cells. These cells showed levels of dark bacteriolysis that ranged between 6% and 13%, with light conditions leading to no significant increase in these levels. Gas chromatography-based analyses showed such incubations to produce no significant changes in the levels of C(16) and C(18) fatty acid chain saturation found in E. coli whole lipid-extracts. It is concluded that the phenothiazinium-based photosensitizers studied may not use E. coli membranes as their primary photodynamic target, but may inflict photodamage on cytoplasmic targets, possibly DNA.

Opsin co-expression in Limulus photoreceptors: differential regulation by light and a circadian clock

PubMed Central

Katti, C.; Kempler, K.; Porter, M. L.; Legg, A.; Gonzalez, R.; Garcia-Rivera, E.; Dugger, D.; Battelle, B.-A.

2010-01-01

A long-standing concept in vision science has held that a single photoreceptor expresses a single type of opsin, the protein component of visual pigment. However, the number of examples in the literature of photoreceptors from vertebrates and invertebrates that break this rule is increasing. Here, we describe a newly discovered Limulus opsin, Limulus opsin5, which is significantly different from previously characterized Limulus opsins, opsins1 and 2. We show that opsin5 is co-expressed with opsins1 and 2 in Limulus lateral and ventral eye photoreceptors and provide the first evidence that the expression of co-expressed opsins can be differentially regulated. We show that the relative levels of opsin5 and opsin1 and 2 in the rhabdom change with a diurnal rhythm and that their relative levels are also influenced by the animal's central circadian clock. An analysis of the sequence of opsin5 suggests it is sensitive to visible light (400–700 nm) but that its spectral properties may be different from that of opsins1 and 2. Changes in the relative levels of these opsins may underlie some of the dramatic day–night changes in Limulus photoreceptor function and may produce a diurnal change in their spectral sensitivity. PMID:20639420

Light sensitometry of mammography films at varying development temperatures and times

PubMed Central

Sharma, Reena; Sharma, Sunil Dutt; Mayya, Y. S.

2012-01-01

Kodak MinR-2000 mammography film is widely used for mammography imaging. The sensitometric indices like base plus fog level (B + F), maximum optical density (ODmax), average gradient (AG) and speed of this film at varying development temperatures and times were evaluated using a light sensitometer. Totally 33 film strips were cut from a single Kodak MinR-2000 mammography film box and exposed in a light sensitometer operated in the green light spectrum to produce a 21-step sensitometric strip. These exposed film strips were processed at temperatures in the range of 32°C–37°C in the step of 1°C and at processing times in the range of 1–6 minutes in the step of 1 minute. The results of the present study show that the measured base plus fog level of the mammography film was not affected much, whereas significant changes were seen in the ODmax, AG and speed with varying development temperatures and times. The ODmax values of the film were found in the range of 3.67–3.76, AG values were in the range of 2.48–3.4 and speed values were in the range of 0.015–0.0236 when the processing temperature was varied from 32°C to 37°C. With processing time variation from 1 to 6 minutes, the observed changes in ODmax values were in the range of 3.54-3.71, changes in AG were in the range of 2.66–3.27 and changes in speed were in the range of 0.011–0.025. Based on these observations, recommendations for optimum processing parameters to be used for this film are made. PMID:22363111

Higher Education Policy and Institutional Change: Intentions and Outcomes in Turbulent Environments.

ERIC Educational Resources Information Center

Trowler, Paul R., Ed.

The chapters in this collection focus on three levels of analysis of higher education: national policymaking, institutional strategy, and the ground level of departments and individual academics. Examples from various countries are analyzed in light of recent theoretical understandings of the policy process. The chapters are: (1) Introduction:…

Study of improving signal-noise ratio for fluorescence channel

NASA Astrophysics Data System (ADS)

Wang, Guoqing; Li, Xin; Lou, Yue; Chen, Dong; Zhao, Xin; Wang, Ran; Yan, Debao; Zhao, Qi

2017-10-01

Laser-induced fluorescence(LIFS), which is one of most effective discrimination methods to identify the material at the molecular level by inducing fluorescence spectrum, has been popularized for its fast and accurate probe's results. According to the research, violet laser or ultraviolet laser is always used as excitation light source. While, There is no atmospheric window for violet laser and ultraviolet laser, causing laser attenuation along its propagation path. What's worse, as the laser reaching sample, part of the light is reflected. That is, excitation laser really react on sample to produce fluorescence is very poor, leading to weak fluorescence mingled with the background light collected by LIFS' processing unit, when it used outdoor. In order to spread LIFS to remote probing under the complex background, study of improving signal-noise ratio for fluorescence channel is a meaningful work. Enhancing the fluorescence intensity and inhibiting background light both can improve fluorescence' signal-noise ratio. In this article, three different approaches of inhibiting background light are discussed to improve the signal-noise ratio of LIFS. The first method is increasing fluorescence excitation area in the proportion of LIFS' collecting field by expanding laser beam, if the collecting filed is fixed. The second one is changing field angle base to accommodate laser divergence angle. The third one is setting a very narrow gating circuit to control acquisition circuit, which is shortly open only when fluorescence arriving. At some level, these methods all can reduce the background light. But after discussion, the third one is best with adding gating acquisition circuit to acquisition circuit instead of changing light path, which is effective and economic.

What happened to smokers’ beliefs about light cigarettes when “light/mild” brand descriptors were banned in the UK? Findings from the International Tobacco Control (ITC) Four Country Survey

PubMed Central

Borland, R; Fong, G T; Yong, H-H; Cummings, K M; Hammond, D; King, B; Siahpush, M; McNeill, A; Hastings, G; O’Connor, R J; Elton-Marshall, T; Zanna, M P

2015-01-01

Aim This paper examines how beliefs of smokers in the UK were affected by the removal of “light” and “mild” brand descriptors, which came into effect on 30 September 2003 for Member States of the European Union (EU). Participants The data come from the first four waves (2002–2005) of the International Tobacco Control Policy Evaluation (ITC) Four-Country Survey, an annual cohort telephone survey of adult smokers in Canada, USA, UK and Australia (15 450 individual cases). Design The UK ban on misleading descriptors occurred around the second wave of data collection in the ITC survey, permitting us to compare beliefs about light cigarettes among adult smokers in the UK before and after the ban, with beliefs in the three other ITC countries unaffected by the ban. Results There was a substantial decline in reported beliefs about the benefits of light cigarettes in the UK following the policy change and an associated public information campaign, but by 2005 (ie, wave 4), these beliefs rebounded slightly and the change in beliefs was no greater than in the USA, where there was no policy change. Conclusions The findings reveal that high levels of misperceptions about light cigarettes existed among smokers in all four countries before and after the EU ban took effect. We cannot conclude that the policy of removing some aspects of misleading labels has been effective in changing beliefs about light cigarettes. Efforts to correct decades of consumer misperceptions about light cigarettes must extend beyond simply removing “light” and “mild” brand descriptors. PMID:18426868

Differential regulation of duplicate light-dependent protochlorophyllide oxidoreductases in the diatom Phaeodactylum tricornutum

DOE PAGES

Hunsperger, Heather M.; Ford, Christopher J.; Miller, James S.; ...

2016-07-01

Diatoms (Bacilliariophyceae) encode two light-dependent protochlorophyllide oxidoreductases (POR1 and POR2) that catalyze the penultimate step of chlorophyll biosynthesis in the light. Algae live in dynamic environments whose changing light levels induce photoacclimative metabolic shifts, including altered cellular chlorophyll levels. We hypothesized that the two POR proteins may be differentially adaptive under varying light conditions. Using the diatom Phaeodactylum tricornutum as a test system, differences in POR protein abundance and por gene expression were examined when this organism was grown on an alternating light:dark cycles at different irradiances; exposed to continuous light; and challenged by a significant decrease in light availability.more » As a result, for cultures maintained on a 12h light: 12h dark photoperiod at 200μEm –2 s –1 ( 200L/D), both por genes were up-regulated during the light and down-regulated in the dark, though por1 transcript abundance rose and fell earlier than that of por2. Little concordance occurred between por1 mRNA and POR1 protein abundance. In contrast, por2 mRNA and POR2 protein abundances followed similar diurnal patterns. When 200L/D P. tricornutum cultures were transferred to continuous light ( 200L/L), the diurnal regulatory pattern of por1 mRNA abundance but not of por2 was disrupted, and POR1 but not POR2 protein abundance dropped steeply. Under 1200μEm –2 s –1 ( 1200L/D), both por1 mRNA and POR1 protein abundance displayed diurnal oscillations. A compromised diel por2 mRNA response under 1200L/D did not impact the oscillation in POR2 abundance. When cells grown at 1200L/D were then shifted to 50μEm –2 s –1 (50L/D), por1 and por2 mRNA levels decreased swiftly but briefly upon light reduction. Thereafter, POR1 but not POR2 protein levels rose significantly in response to this light stepdown.« less

Effects of monochromatic light sources on sex hormone levels in serum and on semen quality of ganders.

PubMed

Chang, Shen-Chang; Zhuang, Zi-Xuan; Lin, Min-Jung; Cheng, Chuen-Yu; Lin, Tsung-Yi; Jea, Yu-Shine; Huang, San-Yuan

2016-04-01

Light is an essential external factor influencing various physiological processes, including reproductive performance, in birds. Although several attempts have been made to understand the effect of light on poultry production, the effect of light of a particular wavelength (color) on the reproductive function in geese remains unclear. This study evaluated the effect of various monochromatic light sources on the levels of sex hormone and on semen quality of ganders. Of 30 male White Roman geese in their third reproductive season (average age=3 years), 27 were divided into three groups receiving monochromatic white or red or blue lights. The birds were kept in an environmentally controlled house with a lighting photoperiod of 7L:17D for six weeks as the adaptation period. The photoperiod was subsequently changed to 9L:15D and maintained for 24 weeks. Three ganders at the beginning of the study and three from each group at the end of the adjusting period and the 20th and 30th week of the study period were sacrificed, and their testes and blood samples were collected for determining the sex hormone levels. Semen samples were collected for determining semen quality parameters, including the semen collection index, sperm concentration, semen volume, sperm motility, sperm viability, sperm morphology, and semen quality factor. The results showed that the testosterone and estradiol levels remained unchanged in all three groups at all time points. The ratio of testosterone to estradiol of ganders exposed to white light was significantly higher than that of ganders exposed to red light at the 30th week (P<0.05). Semen collection index and sperm viability of ganders exposed to blue light were significantly the lowest (P<0.05). Moreover, sperm motility, sperm viability, and percentage of morphologically normal spermatozoa of ganders in white light were the highest (P<0.05). In conclusion, the results of this study suggested that artificial illumination with white light may maintain a better semen quality than that with red or blue lights in ganders. Copyright © 2016 Elsevier B.V. All rights reserved.

Action spectrum for photochemical retinal pigment epithelium (RPE) disruption in an in vivo monkey model

NASA Astrophysics Data System (ADS)

Zhang, Jie; Sabarinathan, Ranjani; Bubel, Tracy; Williams, David R.; Hunter, Jennifer J.

2016-03-01

Observations of RPE disruption and autofluorescence (AF) photobleaching at light levels below the ANSI photochemical maximum permissible exposure (MPE) (Morgan et al., 2008) indicates a demand to modify future light safety standards to protect the retina from harm. To establish safe light exposures, we measured the visible light action spectrum for RPE disruption in an in vivo monkey model with fluorescence adaptive optics retinal imaging. Using this high resolution imaging modality can provide insight into the consequences of light on a cellular level and allow for longitudinal monitoring of retinal changes. The threshold retinal radiant exposures (RRE) for RPE disruption were determined for 4 wavelengths (460, 488, 544, and 594 nm). The anaesthetized macaque retina was exposed to a uniform 0.5° × 0.5° field of view (FOV). Imaging within a 2° × 2° FOV was performed before, immediately after and at 2 week intervals for 10 weeks. At each wavelength, multiple RREs were tested with 4 repetitions each to determine the threshold for RPE disruption. For qualitative analysis, RPE disruption is defined as any detectable change from the pre exposure condition in the cell mosaic in the exposed region relative to the corresponding mosaic in the immediately surrounding area. We have tested several metrics to evaluate the RPE images obtained before and after exposure. The measured action spectrum for photochemical RPE disruption has a shallower slope than the current ANSI photochemical MPE for the same conditions and suggests that longer wavelength light is more hazardous than other measurements would suggest.

Contributions of dental colour to the physical attractiveness stereotype.

PubMed

Montero, J; Gómez-Polo, C; Santos, J A; Portillo, M; Lorenzo, M C; Albaladejo, A

2014-10-01

Dental appearance may play a key role on the way we develop a first impression of another person. To test whether relatively minor changes in the lightness of tooth colour would influence the perceived social appeal (social, intellectual, psychological and relational abilities) of an unknown male and unknown female, this cross-sectional study was performed on 555 Spanish adults. The two major independent variables related to the photograph were tooth lightness (computer-derived), divided into three levels that included lightened teeth, natural teeth and darkened teeth, and the gender of the observed face. Moreover, six independent variables related to the observer were assessed (age, gender, educational level, place of residence, frequency of brushing and self-reported health status). The dependent variables were scored on five-point Likert scales designed to quantify four domains (social, intellectual, psychological and relationship competences) of the Social Appeal Scale (SAS). Tooth lightness influences the perception of social appeal in all dimensions, as darkened smiles received significantly poorer scores than natural-colour smiles, but these were also worse than lightened smiles. A logistic regression analysis revealed that the major predictor of social appeal was tooth lightness, and for each increment in lightness (from darkened to lightened smiles), the odds ratio (OR) of positive values being perceived increased significantly in all items (from 2·3 in Popularity to 6·9 in Happiness). A perceptible change in dental lightness is the strongest factor associated with the dental attractiveness stereotype, affecting significantly the 12 traits assessed, but mainly the Happiness, Social Relations and Academic Performance. © 2014 John Wiley & Sons Ltd.

Changes in olive oil volatile organic compounds induced by water status and light environment in canopies of Olea europaea L. trees.

PubMed

Benelli, Giovanni; Caruso, Giovanni; Giunti, Giulia; Cuzzola, Angela; Saba, Alessandro; Raffaelli, Andrea; Gucci, Riccardo

2015-09-01

Light and water are major factors in fruit development and quality. In this study, the effect of water and light in Olea europaea trees on volatile organic compounds (VOCs) in olive oil was studied over 2 years. Mature fruits were harvested from three zones of the canopy with different light exposure (64%, 42% and 30% of incident light) of trees subjected to full, deficit or complementary irrigation. VOCs were determined by SPME GC-MS and analysed by principal component analysis followed by discriminant analysis to partition treatment effects. Fruit fresh weight and mesocarp oil content decreased in zones where intercepted light was less. Low light levels significantly slowed down fruit maturation, whereas conditions of water deficit accelerated the maturation process. The presence of cyclosativene and α-muurulene was associated with water deficit, nonanal, valencene with full irrigation; α-muurulene, (E)-2-hexanal were related to low light conditions, while trans-β-ocimene, α-copaene, (Z)-2-penten-1-ol, hexanal and nonanal to well exposed zones. The year strongly affected the VOC profile of olive oil. This is the first report on qualitative changes in VOCs induced by light environment and/or water status. This information is valuable to better understand the role of environmental factors on the sensory quality of virgin olive oil. © 2014 Society of Chemical Industry.

Dynamic compartment specific changes in glutathione and ascorbate levels in Arabidopsis plants exposed to different light intensities

PubMed Central

2013-01-01

Background Excess light conditions induce the generation of reactive oxygen species (ROS) directly in the chloroplasts but also cause an accumulation and production of ROS in peroxisomes, cytosol and vacuoles. Antioxidants such as ascorbate and glutathione occur in all cell compartments where they detoxify ROS. In this study compartment specific changes in antioxidant levels and related enzymes were monitored among Arabidopsis wildtype plants and ascorbate and glutathione deficient mutants (vtc2-1 and pad2-1, respectively) exposed to different light intensities (50, 150 which was considered as control condition, 300, 700 and 1,500 μmol m-2 s-1) for 4 h and 14 d. Results The results revealed that wildtype plants reacted to short term exposure to excess light conditions with the accumulation of ascorbate and glutathione in chloroplasts, peroxisomes and the cytosol and an increased activity of catalase in the leaves. Long term exposure led to an accumulation of ascorbate and glutathione mainly in chloroplasts. In wildtype plants an accumulation of ascorbate and hydrogen peroxide (H2O2) could be observed in vacuoles when exposed to high light conditions. The pad2-1 mutant reacted to long term excess light exposure with an accumulation of ascorbate in peroxisomes whereas the vtc2-1 mutant reacted with an accumulation of glutathione in the chloroplasts (relative to the wildtype) and nuclei during long term high light conditions indicating an important role of these antioxidants in these cell compartments for the protection of the mutants against high light stress. Conclusion The results obtained in this study demonstrate that the accumulation of ascorbate and glutathione in chloroplasts, peroxisomes and the cytosol is an important reaction of plants to short term high light stress. The accumulation of ascorbate and H2O2 along the tonoplast and in vacuoles during these conditions indicates an important route for H2O2 detoxification under these conditions. PMID:23865417

Chloroplast thylakoid structure in evergreen leaves employing strong thermal energy dissipation.

PubMed

Demmig-Adams, Barbara; Muller, Onno; Stewart, Jared J; Cohu, Christopher M; Adams, William W

2015-11-01

In nature, photosynthetic organisms cope with highly variable light environments--intensities varying over orders of magnitudes as well as rapid fluctuations over seconds-to-minutes--by alternating between (a) highly effective absorption and photochemical conversion of light levels limiting to photosynthesis and (b) powerful photoprotective thermal dissipation of potentially damaging light levels exceeding those that can be utilized in photosynthesis. Adjustments of the photosynthetic apparatus to changes in light environment involve biophysical, biochemical, and structural adjustments. We used electron micrographs to assess overall thylakoid grana structure in evergreen species that exhibit much stronger maximal levels of thermal energy dissipation than the more commonly studied annual species. Our findings indicate an association between partial or complete unstacking of thylakoid grana structure and strong reversible thermal energy dissipation that, in contrast to what has been reported for annual species with much lower maximal levels of energy dissipation, is similar to what is seen under photoinhibitory conditions. For a tropical evergreen with tall grana stacks, a loosening, or vertical unstacking, of grana was seen in sun-grown plants exhibiting pronounced pH-dependent, rapidly reversible thermal energy dissipation as well as for sudden low-to-high-light transfer of shade-grown plants that responded with photoinhibition, characterized by strong dark-sustained, pH-independent thermal energy dissipation and photosystem II (PSII) inactivation. On the other hand, full-sun exposed subalpine confers with rather short grana stacks transitioned from autumn to winter via conversion of most thylakoids from granal to stromal lamellae concomitant with photoinhibitory photosynthetic inactivation and sustained thermal energy dissipation. We propose that these two types of changes (partial or complete unstacking of grana) in thylakoid arrangement are both associated with the strong non-photochemical quenching (NPQ) of chlorophyll fluorescence (a measure of photoprotective thermal energy dissipation) unique to evergreen species rather than with PSII inactivation per se. Copyright © 2015 Elsevier B.V. All rights reserved.

Association between light-to-dark changes in angle width and iris parameters in light, dark and changes from light-to-dark conditions.

PubMed

Lee, Roland Y; Lin, Shuai-Chun; Chen, Rebecca I; Barbosa, Diego T; Lin, Shan C

2016-09-01

To evaluate the association between light-to-dark changes in angle width parameters and iris parameters in light, dark and changes from light-to-dark conditions. In this prospective, cross-sectional study, anterior segment optical coherence tomography images, obtained under light and dark conditions, were analysed to determine angle opening distance measured at 500 μm from the scleral spur (AOD500), trabecular-iris space area at 500 μm from the scleral spur (TISA500), iris thickness measured at 750 μm from the scleral spur (IT750), iris thickness measured at 2000 μm from the scleral spur (IT2000), iris area (IArea) and pupil diameter (PD). Multivariable linear mixed-effect regression models were used to evaluate the association between light-to-dark changes in angle width parameters (AOD500, TISA500) and iris parameters (IT750, IT2000, IArea, PD) in light, dark and changes from light-to-dark conditions. 534 eyes from 314 non-glaucomatous subjects were analysed. IT750, IT2000, IArea and PD in light conditions were significantly associated with light-to-dark changes in AOD500 (p<0.05). IT750, IT2000 and IArea in light conditions were significantly associated with light-to-dark changes in TISA500 (p<0.05). IT750 in dark conditions was significantly associated with light-to-dark changes in AOD500 and TISA500 (p<0.05). Light-to-dark changes in IT2000, IArea and PD were significantly associated with light-to-dark changes in AOD500 (p<0.05). Light-to-dark changes in IArea were significantly associated with light-to-dark changes in TISA500 (p<0.05). Evaluation of iris parameters in light, dark and changes from light-to-dark conditions demonstrated that IT750, IT2000, IArea and PD in light conditions are significant predictors of light-to-dark changes in angle width. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Magnetic orientation in birds: non-compass responses under monochromatic light of increased intensity.

PubMed

Wiltschko, Wolfgang; Munro, Ursula; Ford, Hugh; Wiltschko, Roswitha

2003-10-22

Migratory Australian silvereyes (Zosterops lateralis) were tested under monochromatic light at wavelengths of 424 nm blue and 565 nm green. At a low light level of 7 x 10(15) quanta m(-2) s(-1) in the local geomagnetic field, the birds preferred their seasonally appropriate southern migratory direction under both wavelengths. Their reversal of headings when the vertical component of the magnetic field was inverted indicated normal use of the avian inclination compass. A higher light intensity of 43 x 10(15) quanta m(-2) s(-1), however, caused a fundamental change in behaviour: under bright blue, the silvereyes showed an axial tendency along the east-west axis; under bright green, they showed a unimodal preference of a west-northwesterly direction that followed a shift in magnetic north, but was not reversed by inverting the vertical component of the magnetic field. Hence it is not based on the inclination compass. The change in behaviour at higher light intensities suggests a complex interaction between at least two receptors. The polar nature of the response under bright green cannot be explained by the current models of light-dependent magnetoreception and will lead to new considerations on these receptive processes.

Trends in leisure time and occupational physical activity in the Madrid region, 1995-2008.

PubMed

Meseguer, Carmen M; Galán, Iñaki; Herruzo, Rafael; Rodríguez-Artalejo, Fernando

2011-01-01

Information on trends in physical activity is very scarce in Mediterranean countries, which have the highest sedentariness in Europe. This study describes recent trends in leisure time physical activity (LTPA) and at work in the Madrid region. The data were taken from representative annual surveys of population aged 18-64 years, between 1995-2008, 28,084 people participated. We calculated total energy, quantified in metabolic equivalent (MET-1 h per week), spent on LTPA and on light LTPA (<3 MET), moderate LTPA (3-6 MET) and vigorous LTPA (>6 MET). The annual change in LTPA was estimated by linear regression, and occupational activity by logistic regression, adjusting for age, gender and educational level. The total amount of LTPA in MET-1 h per week declined by 19.8% (P<.001) between 1995-2008; for both genders, all age groups and educational levels, except for those with the lowest level of education. The adjusted annual change in MET-1 h per week was: -0.21 (P<.001) for total LTPA; -0.1 (P<.001) for light; -0.08 (P<.001) for moderate; and -0.03 (P=.192) for vigorous. This decline is reflected by a shift to the left of the LTPA distribution in the population. Occupational physical inactivity has increased in the general population (odds ratio for annual change=1.01; 95% confidence interval, 1-1.02); specially in women, young and middle aged, and intermediate educational level. There has been a decline in LTPA, mainly in light and moderate activities, accompanied by greater occupational physical inactivity. This could have contributed to the increase in obesity in the Community of Madrid between 1995-2008. Copyright © 2010 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.

Light-regulated leaf expansion in two Populus species: dependence on developmentally controlled ion transport.

PubMed

Stiles, Kari A; Van Volkenburgh, Elizabeth

2002-07-01

Leaf growth responses to light have been compared in two species of Populus, P. deltoides and P. trichocarpa. These species differ markedly in morphology, anatomy, and dependence on light during leaf expansion. Light stimulates the growth rate and acidification of cell walls in P. trichocarpa but not in P. deltoides, whereas leaves of P. deltoides maintain growth in the dark. Light-induced growth is promoted in P. deltoides when cells are provided 50-100 mM KCl. In both species, light initially depolarizes, then hyperpolarizes mesophyll plasma membranes. However, in the dark, the resting E(m) of mesophyll cells in P. deltoides, but not in P. trichocarpa, is relatively insensitive to decade changes in external [K+]. Results suggest that light-stimulated leaf growth depends on developmentally regulated cellular mechanisms controlling ion fluxes across the plasma membrane. These developmental differences underlie species-level differences in growth and physiological responses to the photoenvironment.

Changing lamp type and position to improve lighting quality

NASA Astrophysics Data System (ADS)

Anizar; Syahputri, K.; Sari, RM; Rizkya, I.; Hardianti, DA

2018-03-01

This study investigates the lighting quality on the production floor in a cigarette paper industry by measuring illumination level and luminance. Cigarette paper inspection is performed manually by operators, and the criteria of defects are the cigarette paper has a hole, is rough and dirty. Operators complain that the room is pretty dark, which makes them unable to see clearly the cigarette paper defect. The government of Indonesia Health Ministerial Decree No 1405 The Year 2002 states that illumination level for continuous manual labor is 200 lux. Illumination level is measured for four days at 08.00, 10.00, 12.30, and 14.00 o’clock with 4 in 1 environmental meter. From the measurement result, it is found that using 7 LED lamps of 60 Watts can produce average illumination level of 70 lux. Low illuminance is caused by illumination level that does not meet the need 0f 569.759 lumen. Alternatives that can be used to increase lumen number are changing lamp type and position. One of the possibilities is using 24 LED of 138 Watts set 5.7 meters apart from one another can meet this demand. Another is using 5 LED of 150 Watts installed above the field of work.

Sustained Diurnal Stimulation of Cyclic Electron Flow in Two Tropical Tree Species Erythrophleum guineense and Khaya ivorensis

PubMed Central

Huang, Wei; Yang, Ying-Jie; Hu, Hong; Cao, Kun-Fang; Zhang, Shi-Bao

2016-01-01

The photosystem II (PSII) activity of C3 plants is usually inhibited at noon associated with high light but can be repaired fast in the afternoon. However, the diurnal variation of photosystem I (PSI) activity is unknown. Although, cyclic electron flow (CEF) has been documented as an important mechanism for photosynthesis, the diurnal variation of CEF in sun leaves is little known. We determined the diurnal changes in PSI and PSII activities, light energy dissipation in PSII and the P700 redox state in two tropical tree species Erythrophleum guineense and Khaya ivorensis grown in an open field. The PSI activity (as indicated by the maximum quantity of photo-oxidizable P700) was maintained stable during the daytime. CEF was strongly activated under high light at noon, accompanying with high levels of non-photochemical quenching (NPQ) and PSI oxidation ratio. In the afternoon, CEF was maintained at a relatively high level under low light, which was accompanied with low levels of NPQ and P700 oxidation ratio. These results indicated that CEF was flexibly modulated during daytime under fluctuating light conditions. Under high light at noon, CEF-dependent generation of proton gradient across the thylakoid membranes (ΔpH) mainly contributed to photoprotection for PSI and PSII. By comparison, at low light in the afternoon, the CEF-dependent formation of ΔpH may be important for PSII repair via an additional ATP synthesis. PMID:27486473

Kerosene lighting contributes to household air pollution in rural Uganda.

PubMed

Muyanja, D; Allen, J G; Vallarino, J; Valeri, L; Kakuhikire, B; Bangsberg, D R; Christiani, D C; Tsai, A C; Lai, P S

2017-09-01

The literature on the contribution of kerosene lighting to indoor air particulate concentrations is sparse. In rural Uganda, kitchens are almost universally located outside the main home, and kerosene is often used for lighting. In this study, we obtained longitudinal measures of particulate matter 2.5 microns or smaller in size (PM 2.5 ) from living rooms and kitchens of 88 households in rural Uganda. Linear mixed-effects models with a random intercept for household were used to test the hypotheses that primary reported lighting source and kitchen location (indoor vs outdoor) are associated with PM 2.5 levels. During initial testing, households reported using the following sources of lighting: open-wick kerosene (19.3%), hurricane kerosene (45.5%), battery-powered (33.0%), and solar (1.1%) lamps. During follow-up testing, these proportions changed to 29.5%, 35.2%, 18.2%, and 9.1%, respectively. Average ambient, living room, and kitchen PM 2.5 levels were 20.2, 35.2, and 270.0 μg/m 3 . Living rooms using open-wick kerosene lamps had the highest PM 2.5 levels (55.3 μg/m 3 ) compared to those using solar lighting (19.4 μg/m 3 ; open wick vs solar, P=.01); 27.6% of homes using open-wick kerosene lamps met World Health Organization indoor air quality standards compared to 75.0% in homes using solar lighting. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Dynamics of Photosystem II and Its Light Harvesting System in Response to Light Changes in the Halotolerant Alga Dunaliella salina1

PubMed Central

Pick, Uri; Gounaris, Kleoniki; Barber, James

1987-01-01

A photosystem two (PSII) core complex consisting of five major polypeptides (47, 40, 32, 30, and 10 kilodaltons) and a light harvesting chlorophyll a/b complex (LHC-2) have been isolated from the halotolerant alga Dunaliella salina. The chlorophyll and polypeptide composition of both complexes were compared in illuminated and dark-adapted cultures. Dark adaptation is accompanied by a decrease in the chlorophyll a to chlorophyll b (Chl a/Chl b) ratio of intact thylakoids without any change in total chlorophyll. These changes occur with a half-time of 3 hours and are reversed upon reillumination. Analyses of PSII enriched membrane fragments suggest that the decrease in the Chl a/Chl b is due partly to an increase in the Chl b content of LHC-2 and partly to changes in the relative levels of the two complexes. Apparently during dark adaptation there is: (a) a net synthesis of chlorophyll b, (b) removal of PSII core complexes resulting in a 2-fold drop in the PSII cores to LHC-2 chlorophyll ratio. These changes should dramatically increase the light harvesting capacity of the remaining PSII reaction centers. Presumably this adjustment of antenna size and composition is a physiological mechanism necessary for responding to shade conditions. Also detected, using 32P, are light-induced phosphorylation of the LHC-2 (consistent with the ability to undergo State transitions) and of the 40 and 30 kilodalton subunits of the PSII core complex. These observations indicate that additional mechanisms may also exist to help optimize the interception of quanta during rapid changes in illumination conditions. Images Fig. 4 PMID:16665656

Changes in surface morphology and mineralization level of human enamel following in-office bleaching with 35% hydrogen peroxide and light irradiation.

PubMed

Berger, Sandrine Bittencourt; Cavalli, Vanessa; Ambrosano, Glaucia Maria Bovi; Giannini, Marcelo

2010-01-01

The objective of this study was to evaluate the alterations on surface morphology and mineral loss of human enamel following in-office bleaching with 35% hydrogen peroxide and light irradiation. Dental enamel samples were obtained from human third molars and randomly divided into 10 groups (n = 10). The control group remained untreated. Bleached groups were treated with one of three whitening products. Bleaching was performed in a single session, during which bleaching gel was applied to the enamel surface three times for 10 minutes each time. During treatment, the bleaching agents were either irradiated by a halogen light or an LED/diode laser or were not irradiated at all. Microhardness testing was performed with a Knoop indentor and the surface morphologic observations were carried out by scanning electron microscopy (SEM). Cross-sectional microhardness (CSMH) and polarized light microscopy (PLM) were used to measure the depth of demineralization. The results revealed a significant decrease in surface microhardness values and changes to the enamel morphology after bleaching. CSMH and PLM showed that bleached enamel presented lower volume percentage of mineral up to 40 micrometers from the enamel surface and demineralization areas located in the subsuperficial region of enamel, respectively. It was concluded that 35% hydrogen peroxide can alter the surface morphology and the mineralization level of the dental enamel surface and sub-surface regardless of what type of bleaching light is used.

Aging: commentary. Change in perceptions of personality disorder in late life: the view from socioemotional aging.

PubMed

Isaacowitz, Derek M

2014-02-01

Cooper, Balsis, and Oltmanns (2014) present evidence that older adults view changes in their own levels of personality disorders, but that their informants do not report such positive changes. In this commentary, the author considers these provocative findings in light of current theory and research from socioemotional aging on emotion-cognition links and how they might vary as a function of age.

NAD+ maintenance attenuates light induced photoreceptor degeneration Δ

PubMed Central

Bai, Shi; Sheline, Christian T.

2013-01-01

Light-induced retinal damage (LD) occurs after surgery or sun exposure. We previously showed that zinc (Zn2+) accumulated in photoreceptors and RPE cells after LD but prior to cell death, and pyruvate or nicotinamide attenuated the resultant death perhaps by restoring nicotinamide adenine dinucleotide (NAD+) levels. We first examined the levels of NAD+ and the efficacy of pyruvate or nicotinamide in oxidative toxicities using primary retinal cultures. We next manipulated NAD+ levels in vivo and tested the affect on LD to photoreceptors and RPE. NAD+ levels cycle with a 24-h rhythm in mammals, which is affected by the feeding schedule. Therefore, we tested the affect of increasing NAD+ levels on LD by giving nicotinamide, inverting the feeding schedule, or using transgenic mice which overexpress cytoplasmic nicotinamide mononucleotide adenyl-transferase-1 (cytNMNAT1), an NAD+ synthetic enzyme. Zn2+ accumulation was also assessed in culture and in retinal sections. Retinas of light damaged animals were examined by OCT and plastic sectioning, and retinal NAD levels were measured. Day fed, or nicotinamide treated rats showed less NAD+ loss, and LD compared to night fed rats or untreated rats without changing the Zn2+ staining pattern. CytNMNAT1 showed less Zn2+ staining, NAD+ loss, and cell death after LD. In conclusion, intense light, Zn2+ and oxidative toxicities caused an increase in Zn2+, NAD+ loss, and cell death which were attenuated by NAD+ restoration. Therefore, NAD+ levels play a protective role in LD-induced death of photoreceptors and RPE cells. PMID:23274583

Sequential light programs shape kale (Brassica napus) sprout appearance and alter metabolic and nutrient content

PubMed Central

Carvalho, Sofia D; Folta, Kevin M

2014-01-01

Different light wavelengths have specific effects on plant growth and development. Narrow-bandwidth light-emitting diode (LED) lighting may be used to directionally manipulate size, color and metabolites in high-value fruits and vegetables. In this report, Red Russian kale (Brassica napus) seedlings were grown under specific light conditions and analyzed for photomorphogenic responses, pigment accumulation and nutraceutical content. The results showed that this genotype responds predictably to darkness, blue and red light, with suppression of hypocotyl elongation, development of pigments and changes in specific metabolites. However, these seedlings were relatively hypersensitive to far-red light, leading to uncharacteristically short hypocotyls and high pigment accumulation, even after growth under very low fluence rates (<1 μmol m−2 s−1). General antioxidant levels and aliphatic glucosinolates are elevated by far-red light treatments. Sequential treatments of darkness, blue light, red light and far-red light were applied throughout sprout development to alter final product quality. These results indicate that sequential treatment with narrow-bandwidth light may be used to affect key economically important traits in high-value crops. PMID:26504531

Restless roosts: Light pollution affects behavior, sleep, and physiology in a free-living songbird.

PubMed

Ouyang, Jenny Q; de Jong, Maaike; van Grunsven, Roy H A; Matson, Kevin D; Haussmann, Mark F; Meerlo, Peter; Visser, Marcel E; Spoelstra, Kamiel

2017-11-01

The natural nighttime environment is increasingly polluted by artificial light. Several studies have linked artificial light at night to negative impacts on human health. In free-living animals, light pollution is associated with changes in circadian, reproductive, and social behavior, but whether these animals also suffer from physiologic costs remains unknown. To fill this gap, we made use of a unique network of field sites which are either completely unlit (control), or are artificially illuminated with white, green, or red light. We monitored nighttime activity of adult great tits, Parus major, and related this activity to within-individual changes in physiologic indices. Because altered nighttime activity as a result of light pollution may affect health and well-being, we measured oxalic acid concentrations as a biomarker for sleep restriction, acute phase protein concentrations and malaria infection as indices of immune function, and telomere lengths as an overall measure of metabolic costs. Compared to other treatments, individuals roosting in the white light were much more active at night. In these individuals, oxalic acid decreased over the course of the study. We also found that individuals roosting in the white light treatment had a higher probability of malaria infection. Our results indicate that white light at night increases nighttime activity levels and sleep debt and affects disease dynamics in a free-living songbird. Our study offers the first evidence of detrimental effects of light pollution on the health of free-ranging wild animals. © 2017 John Wiley & Sons Ltd.

Effects of intracellular injection of calcium buffers on light adaptation in Limulus ventral photoreceptors

PubMed Central

1975-01-01

The calcium sequestering agent, EGTA, was injected into Limulus ventral photoreceptors. Before injection, the inward membrane current induced by a long stimulus had a large initial transient which declined to a smaller plateau. Iontophoretic injection of EGTA tended to prevent the decline from transient to plateau. Before injection the plateau response was a nonlinear function of light intensity. After EGTA injection the response-intensity curves tended to become linear. Before injection, bright lights lowered the sensitivity as determined with subsequent test flashes. EGTA injection decreased the light-induced changes in sensitivity. Ca-EGTA buffers having different levels of free calcium were pressure-injected into ventral photoreceptors; the higher the level of free calcium, the lower the sensitivity measured after injection. The effects of inotophoretic injection of EGTA were not mimicked by injection or similar amounts of sulfate and the effects of pressure injection of EGTA buffer solutions were not mimicked by injection of similar volumes of pH buffer or mannitol. The data are consistent with the hypothesis that light adaptation is mediated by a rise of the intracellular free calcium concentration. PMID:810540

Investigation of the role of the calvin cycle and C1 metabolism during HCHO metabolism in gaseous HCHO-treated petunia under light and dark conditions using 13C-NMR.

PubMed

Sun, Huiqun; Zhang, Wei; Tang, Lijuan; Han, Shuang; Wang, Xinjia; Zhou, Shengen; Li, Kunzhi; Chen, Limei

2015-01-01

It has been shown that formaldehyde (HCHO) absorbed by plants can be assimilated through the Calvin cycle or C1 metabolism. Our previous study indicated that Petunia hybrida could effectively eliminate HCHO from HCHO-polluted air. To understand the roles of C1 metabolism and the Calvin cycle during HCHO metabolism and detoxification in petunia plants treated with gaseous H(13)CHO under light and dark conditions. Aseptically grown petunia plants were treated with gaseous H(13)CHO under dark and light conditions. The metabolites generated from HCHO detoxification in petunia were investigated using (13)C-NMR. [2-(13)C]glycine (Gly) was generated via C1 metabolism and [U-(13)C]glucose (Gluc) was produced through the Calvin cycle simultaneously in petunia treated with low-level gaseous H(13)CHO under light conditions. Generation of [2-(13)C]Gly decreased whereas [U-(13) C]Gluc and [U-(13)C]fructose (Fruc) production increased greatly under high-level gaseous H(13)CHO stress in the light. In contrast, [U-(13)C]Gluc and [U-(13)C] Fruc production decreased greatly and [2-(13)C]Gly generation increased significantly under low-level and high-level gaseous H(13)CHO stress in the dark. C1 metabolism and the Calvin cycle contributed differently to HCHO metabolism and detoxification in gaseous H(13CHO-treated petunia plants. As the level of gaseous HCHO increased, the role of C1 metabolism decreased and the role of the Calvin cycle increased under light conditions. However, opposite changes were observed in petunia plants under dark conditions. Copyright © 2015 John Wiley & Sons, Ltd.

Receptoral and postreceptoral visual processes in recovery from chromatic adaptation.

PubMed Central

Jameson, D; Hurvich, L M; Varner, F D

1979-01-01

The time course of recovery from chromatic adaptation in human vision was tracked by determining the wavelength of light that appears uniquely yellow (neither red nor green) both before and after exposure to yellowish green and yellowish red adapting lights. Recovery is complete within 5 min after steady light exposure. After exposure to the alternating repeated sequence 10-sec light/10-sec dark, the initial magnitude of the aftereffect is reduced but recovery is retarded. The results are interpreted in terms of two processes located at different levels in the hierarchical organization of the visual system. One is a change in the balance of cone receptor sensitivities; the second is a shift in the equilibrium baseline between opposite-signed responses of the red/green channel at the opponent-process neural level. The baseline-shift mechanism is effective in the condition in which repeated input signals originating at the receptors are of sufficient strength to activate the system effectively. Hence, this process is revealed in the alternating adaptation condition when the receptors undergo partial recovery after each light exposure, but receptor adaptation during continued steady light exposure effectively protects the subsequent neural systems from continued strong activation. PMID:288087

Safety Evaluation of the Lighting at the Entrance of a Very Long Road Tunnel: A Case Study in Ilam.

PubMed

Mehri, Ahmad; Hajizadeh, Roohalah; Farhang Dehghan, Somayeh; Nassiri, Parvin; Jafari, Sayed Mohammad; Taheri, Fereshteh; Zakerian, Seyed Abolfazl

2017-06-01

At the entrance of a tunnel, reflection of sunlight from the surrounding environment and a lack of adequate lighting usually cause some vision problems. The purpose of this study was to perform a safety evaluation of lighting on a very long road in Ilam, Iran. The average luminance was measured using a luminance meter (model S3; Hagner, Solna, Sweden). A camera (model 108, 35-mm single-lens reflex; Yashica, Nagano, Japan) was used to take photographs of the safe stopping distance from the tunnel entrance. Equivalent luminance was determined according to the Holliday polar diagram. Considering the average luminance at the tunnel entrance (116.7 cd/m 2 ) and using Adrian's equation, the safe level of lighting at the entrance of the tunnel was determined to be 0.7. A comparison between the results of the safe levels of lighting at the entrance of the tunnel and the De Boer scale showed that the phenomenon of black holes is created at the tunnel entrance. This may lead to a misadaptation of the drivers' eyes to the change in luminance level at the entrance of the tunnel, thereby increasing the risk of road accidents in this zone.

Long-term effects of seven cleaning methods on light transmittance, surface roughness, and flexural modulus of polyurethane retainer material.

PubMed

Agarwal, Manika; Wible, Emily; Ramir, Tyler; Altun, Sibel; Viana, Grace; Evans, Carla; Lukic, Henry; Megremis, Spiro; Atsawasuwan, Phimon

2018-05-01

To evaluate the long-term effects of seven different cleaning methods on light transmittance, surface roughness, and flexural modulus of a polyurethane retainer material. Polyurethane retainer specimens (Vivera®, Align Technology Inc) (70 specimens, n = 10 per method, 50.8 mm × 12.7 mm × 1.0 mm) were exposed to seven cleaning methods twice a week for 6 months. Before treatment and after 6 months, light transmittance, surface roughness, and flexural modulus of the specimens were quantified. Qualitative assessment of randomly selected specimens from each solution was performed at baseline and after 6 months using a scanning electron microscope. Statistical analyses were performed at the .05 significance level. Of the three test variables, light transmittance through the specimens was the only one that changed significantly from baseline to 6 months for all cleaning solutions, with all of them causing a decrease. However, except for 0.6% sodium hypochlorite showing a change in surface roughness values and 2.5% vinegar and toothbrushing showing an increase in flexural modulus, none of the other four cleaning methods resulted in significant changes in surface roughness or flexural modulus values for the polyurethane specimens between baseline and after 6 months. Of the seven cleaning methods, Invisalign® cleaning crystals, Polident®, and Listerine® showed the least amount of change in light transmittance values for the polyurethane specimens over 6 months, and they had no effect on surface roughness and flexural modulus values.

Magnetic field effects on mitochondrion-activity-related optical properties in slime mold and bone forming cells.

PubMed

Mizukawa, Yuri; Iwasaka, Masakazu

2013-01-01

In the present study, a cellular level response of Cyto-aa3 oxidation was investigated in real time under both time-varying and strong static magnetic fields of 5 T. Two kinds of cells, a slime mold, Physarum polycephalum, and bone forming cells, MC-3T3-E1, were used for the experiments. The oxidation level of the Cyto-aa3 was calculated by optical absorptions at 690 nm, 780 nm and 830 nm. The sample, fiber-optics and an additional optical fiber for light stimulation were set in a solenoidal coil or the bore of a 5-T superconducting magnet. The solenoidal coil for time-varying magnetic fields produced sinusoidal magnetic fields of 6 mT. The slime mold showed a periodic change in Cyto-aa3 oxidation, and the oxidation-reduction cycle of Cyto-aa3 was apparently changed when visible-light irradiated the slime mold. Similarly to the case with light, time-varying magnetic stimulations changed the oxidation-reduction cycle during and after the stimulation for 10 minutes. The same phenomena were observed in the MC-3T3-E1 cell assembly, although their cycle rhythm was comparatively random. Finally, magnetic field exposure of up to 5 T exhibited a distinct suppression of Cyto-aa3 oscillation in the bone forming cells. Exposure up to 5 T was repeated five times, and the change in Cyto-aa3 oxidation reproducibly occurred.

Stable Nighttime Light Decreased in Protected Area of California: Findings from DMSP-OLS Observations and the Importance for Protected Area Policy Making

NASA Astrophysics Data System (ADS)

Jia, S.; Gillespie, T. W.

2016-12-01

Stable nighttime light, an indicator of persisting human activity and light pollution is a well-recognized disturbance to the wilderness of protected areas (PAs). Mostly supported by in situ observations, very limited studies of light pollution for PAs focused at a regional level and on a continuous time span to support policy making effectively. DMSP-OLS stable nighttime series provide continuous observation of nightlight and have been widely applied in studies focusing on human activities. In this study, we employed inter-calibrated DMSP-OLS nightlight series from 1992 to 2012 to evaluate the change of intensity and extension of stable nighttime light inside California PAs. We observed a decrease of stable nighttime light and a shrinkage in spatial extent in PAs located in all ecoregions from 1992 to 2012, especially before 2004. Such decrease and shrinkage occurred mostly in southern California and the Bay Area where mega metropolitan clusters locate. The successful application of protecting strategies in PAs and the improved technologies of lighting may contribute to the relieving of light pollution in PAs. However, the stable nighttime light slightly increased since 2004, when there was limited room for stricter protective regulations and the pressure from population growth persisted. Population density explained most spatial distribution of nightlight in years with census tract level demographic data available, except PAs with the highest wilderness such as Sierra Nevada Mts. We anticipate to improve the models with the newest remote sensing nighttime product from NASA Suomi-NPP and annually updated demographic data from American Community Survey at census tract level in the future to provide a cost-effective evaluation on protecting strategies. Such evaluation will support land managers of PAs and local policy-makers for modification and proposal of policies.

The ctenidium of the giant clam, Tridacna squamosa, expresses an ammonium transporter 1 that displays light-suppressed gene and protein expression and may be involved in ammonia excretion.

PubMed

Boo, Mel V; Hiong, Kum C; Goh, Enan J K; Choo, Celine Y L; Wong, Wai P; Chew, Shit F; Ip, Yuen K

2018-04-24

Ammonium transporters (AMTs) can participate in ammonia uptake or excretion across the plasma membrane of prokaryotic, plant and invertebrate cells. The giant clam, Tridacna squamosa, harbors nitrogen-deficient symbiotic zooxanthellae, and normally conducts light-enhanced ammonia absorption to benefit the symbionts. Nonetheless, it can excrete ammonia when there is a supply of exogenous nitrogen or exposed to continuous darkness. This study aimed to elucidate the role of AMT1 in the ctenidium of T. squamosa by cloning and characterizing the AMT1/AMT1, determining its subcellular localization, and examining changes in its transcript and protein expression levels in response to light exposure. The cDNA coding sequence of AMT1 from T. squamosa consisted of 1527 bp and encoded 508 amino acids of 54.6 kDa. AMT1-immunofluorescence was detected mainly at the apical epithelium of ctenidial filaments, and it decreased significantly after 12 h of exposure to light. By contrast, the epithelial cells surrounding the tertiary water channels in the ctentidium, which are known to exhibit light-enhanced glutamine synthetase expression and take part in the assimilation of exogenous ammonia in light, did not display any AMT1-immunolabelling. Furthermore, the transcript level and protein abundance of ctenidial AMT1/AMT1 decreased significantly at the 6th and 12th h of light exposure. Taken together, these results indicate that AMT1 might participate in ammonia excretion instead of ammonia absorption and assimilation in T. squamosa. It is probable that the expression levels of AMT1/AMT1 need to be down-regulated during light exposure to achieve light-enhanced ammonia uptake.

Elymus repens biomass allocation and acquisition as affected by light and nutrient supply and companion crop competition

PubMed Central

Ringselle, Björn; Prieto-Ruiz, Inés; Andersson, Lars; Aronsson, Helena; Bergkvist, Göran

2017-01-01

Background and Aims Competitive crops are a central component of resource-efficient weed control, especially for problematic perennial weeds such as Elymus repens. Competition not only reduces total weed biomass, but denial of resources can also change the allocation pattern – potentially away from the underground storage organs that make perennial weeds difficult to control. Thus, the competition mode of crops may be an important component in the design of resource-efficient cropping systems. Our aim was to determine how competition from companion crops with different modes of competition affect E. repens biomass acquisition and allocation and discuss that in relation to how E. repens responds to different levels of light and nutrient supply. Methods Greenhouse experiments were conducted with E. repens growing in interspecific competition with increasing density of perennial ryegrass or red clover, or growing at three levels of both light and nutrient supply. Key Results Elymus repens total biomass decreased with increasing biomass of the companion crop and the rate of decrease was higher with red clover than with perennial ryegrass, particularly for E. repens rhizome biomass. A reduced nutrient supply shifted E. repens allocation towards below-ground biomass while a reduced light supply shifted it towards shoot biomass. Red clover caused no change in E. repens allocation pattern, while ryegrass mostly shifted the allocation towards below-ground biomass, but the change was not correlated with ryegrass biomass. Conclusions The companion crop mode of competition influences both the suppression rate of E. repens biomass acquisition and the likelihood of shifts in E. repens biomass allocation. PMID:28025285

Tracking Dynamic Changes and Monitoring Socioeconomic Parameters in Algeria Between 1993 and 2012, Using Nighttime Light Remote Sensing

NASA Astrophysics Data System (ADS)

Faouzi, B.; Washaya, P.

2017-09-01

This paper is based on using DMSP-OLS data from satellites nighttime light observations to detect both sources of light emissions in Algeria from human settlement areas and gas flaring from oil-extraction and natural gas production. We used the time series of data from DMSP-OLS images to examine the spatial and temporal characteristics of urban development in 48 Algerian provinces from 1993 to 2012. A systematic nighttime light calibration method was used to improve the consistency and comparability of the DSMPOSL images and then a separation is made between light detected from human settlements and light detected from gas flaring in order to allow us to study human settlements without other light emissions and then assess the suitability of using DMSP data in southern Algeria and its ability to monitor gas flaring. Linear regression methods were developed to identify the dynamic change of nighttime light and estimated its growth directions at pixel level. This work is the first to use nighttime light observations to detect and monitor the growth of human settlements in North Africa. In this study, we made use of DMSP-OLS data as a return ticket to the years of crises and we found the most affected provinces during that period. The DMSP-OLS data proved to be an index of growth in the economy during the period of stability in Algeria expressed by positive dynamic changes in the lighted area in all Algerian provinces. We used NTL data as an alternative to annual growth indexes for each province, which are unavailable, and its help as a monitoring system for socioeconomic parameters to fill the gap of data availability. We also proposed nighttime light remote sensing data as a useful tool to control and reduce CO2 emissions in Algeria's petroleum sector.

Solar irradiance changes and photobiological effects at earth's surface following astrophysical ionizing radiation events.

PubMed

Thomas, Brian C; Neale, Patrick J; Snyder, Brock R

2015-03-01

Astrophysical ionizing radiation events have been recognized as a potential threat to life on Earth, primarily through depletion of stratospheric ozone and subsequent increase in surface-level solar ultraviolet radiation. Simulations of the atmospheric effects of a variety of events (such as supernovae, gamma-ray bursts, and solar proton events) have been previously published, along with estimates of biological damage at Earth's surface. In this work, we employed the Tropospheric Ultraviolet and Visible (TUV) radiative transfer model to expand and improve calculations of surface-level irradiance and biological impacts following an ionizing radiation event. We considered changes in surface-level UVB, UVA, and photosynthetically active radiation (visible light) for clear-sky conditions and fixed aerosol parameter values. We also considered a wide range of biological effects on organisms ranging from humans to phytoplankton. We found that past work overestimated UVB irradiance but that relative estimates for increase in exposure to DNA-damaging radiation are still similar to our improved calculations. We also found that the intensity of biologically damaging radiation varies widely with organism and specific impact considered; these results have implications for biosphere-level damage following astrophysical ionizing radiation events. When considering changes in surface-level visible light irradiance, we found that, contrary to previous assumptions, a decrease in irradiance is only present for a short time in very limited geographical areas; instead we found a net increase for most of the modeled time-space region. This result has implications for proposed climate changes associated with ionizing radiation events.

Interaction of Temperature and Photoperiod Increases Growth and Oil Content in the Marine Microalgae Dunaliella viridis

PubMed Central

Howard, Brian; Dvora, Mia; Dums, Jacob; Backman, Patrick; Sederoff, Heike

2015-01-01

Eukaryotic marine microalgae like Dunaliella spp. have great potential as a feedstock for liquid transportation fuels because they grow fast and can accumulate high levels of triacylgycerides with little need for fresh water or land. Their growth rates vary between species and are dependent on environmental conditions. The cell cycle, starch and triacylglycerol accumulation are controlled by the diurnal light:dark cycle. Storage compounds like starch and triacylglycerol accumulate in the light when CO2 fixation rates exceed the need of assimilated carbon and energy for cell maintenance and division during the dark phase. To delineate environmental effects, we analyzed cell division rates, metabolism and transcriptional regulation in Dunaliella viridis in response to changes in light duration and growth temperatures. Its rate of cell division was increased under continuous light conditions, while a shift in temperature from 25°C to 35°C did not significantly affect the cell division rate, but increased the triacylglycerol content per cell several-fold under continuous light. The amount of saturated fatty acids in triacylglycerol fraction was more responsive to an increase in temperature than to a change in the light regime. Detailed fatty acid profiles showed that Dunaliella viridis incorporated lauric acid (C12:0) into triacylglycerol after 24 hours under continuous light. Transcriptome analysis identified potential regulators involved in the light and temperature-induced lipid accumulation in Dunaliella viridis. PMID:25992838

Accelerated aging effects on surface hardness and roughness of lingual retainer adhesives.

PubMed

Ramoglu, Sabri Ilhan; Usumez, Serdar; Buyukyilmaz, Tamer

2008-01-01

To test the null hypothesis that accelerated aging has no effect on the surface microhardness and roughness of two light-cured lingual retainer adhesives. Ten samples of light-cured materials, Transbond Lingual Retainer (3M Unitek) and Light Cure Retainer (Reliance) were cured with a halogen light for 40 seconds. Vickers hardness and surface roughness were measured before and after accelerated aging of 300 hours in a weathering tester. Differences between mean values were analyzed for statistical significance using a t-test. The level of statistical significance was set at P < .05. The mean Vickers hardness of Transbond Lingual Retainer was 62.8 +/- 3.5 and 79.6 +/- 4.9 before and after aging, respectively. The mean Vickers hardness of Light Cure Retainer was 40.3 +/- 2.6 and 58.3 +/- 4.3 before and after aging, respectively. Differences in both groups were statistically significant (P < .001). Following aging, mean surface roughness was changed from 0.039 microm to 0.121 microm and from 0.021 microm to 0.031 microm for Transbond Lingual Retainer and Light Cure Retainer, respectively. The roughening of Transbond Lingual Retainer with aging was statistically significant (P < .05), while the change in the surface roughness of Light Cure Retainer was not (P > .05). Accelerated aging significantly increased the surface microhardness of both light-cured retainer adhesives tested. It also significantly increased the surface roughness of the Transbond Lingual Retainer.

Action spectra of chlorophyll a biosynthesis in cyanobacteria: dark-operative protochlorophyllide oxidoreductase-deficient mutants.

PubMed

Gao, Yang; Xiong, Wei; He, Ming J; Tang, Li; Xiang, Jin Y; Wu, Qing Y

2009-01-01

Both light-dependent and light-independent (dark) protochlorophyllide (Pchlide) reductase account for catalyzing the reduction of Pchlide to chlorophyllide during the biosynthesis of Mg-tetrapyrrole pigments in cyanobacteria. To gain more insight into the interaction between the wavelength of the light and these two chlorophyll synthetic pathways in Synechocystis sp. PCC 6803, the spectral effectiveness of the formation of chlorophyll a was investigated during the regreening process in chlL(-) and chlN(-) mutants, which could not synthesize chlorophyll during growth in the dark. The action spectra showed obvious maxima around 450 nm and 650 nm, similar to those of higher plants except that the intensities of two peaks are reversed. The mRNA levels of chlL and chlN and chlorophyll a content under different wavelengths of light in the wild-type strain were also measured. The RT-PCR analysis revealed that the transcripts of chlL and chlN were up-regulated in red light but simultaneously down-regulated in green light which resulted in corresponding changes of the chlorophyll content. This fact indicates that the regulation of dark-operative protochlorophyllide oxidoreductase (DPOR) in the transcriptional level is essential for cyanobacteria to synthesize appropriate chlorophyll for acclimating in various light colour environments.

Limits to physiological plasticity of the coral Pocillopora verrucosa from the central Red Sea

NASA Astrophysics Data System (ADS)

Ziegler, Maren; Roder, Cornelia M.; Büchel, Claudia; Voolstra, Christian R.

2014-12-01

Many coral species display changing distribution patterns across coral reef depths. While changes in the underwater light field and the ability to associate with different photosynthetic symbionts of the genus Symbiodinium explain some of the variation, the limits to physiological plasticity are unknown for most corals. In the central Red Sea, colonies of the branching coral Pocillopora verrucosa are most abundant in shallow high light environments and become less abundant in water depths below 10 m. To further understand what determines this narrow distribution, we conducted a cross-depths transplant experiment looking at physiological plasticity and acclimation in regard to depth. Colonies from 5, 10, and 20 m were collected, transplanted to all depths, and re-investigated after 30 and 210 d. All coral colonies transplanted downward from shallow to deep water displayed an increase in photosynthetic light-harvesting pigments, which resulted in higher photosynthetic efficiency. Shallow-water specimens transplanted to deeper water showed a significant decrease in total protein content after 30 and 210 d under low light conditions compared to specimens transplanted to shallow and medium depths. Stable isotope data suggest that heterotrophic input of carbon was not increased under low light, and consequently, decreasing protein levels were symptomatic of decreasing photosynthetic rates that could not be compensated for through higher light-harvesting efficiency. Our results provide insights into the physiological plasticity of P. verrucosa in changing light regimes and explain the observed depth distribution pattern. Despite its high abundance in shallow reef waters, P. verrucosa possesses limited heterotrophic acclimation potential, i.e., the ability to support its mainly photoautotrophic diet through heterotrophic feeding. We conclude that P. verrucosa might be a species vulnerable to sudden changes in underwater light fields resulting from processes such as increased turbidity caused by coastal development along the Saudi Arabian Red Sea coast.

Conifer expansion reduces the competitive ability and herbivore defense of aspen by modifying light environment and soil chemistry.

PubMed

Calder, W John; Horn, Kevin J; St Clair, Samuel B

2011-06-01

Disturbance patterns strongly influence plant community structure. What remains less clear, particularly at a mechanistic level, is how changes in disturbance cycles alter successional outcomes in plant communities. There is evidence that fire suppression is resulting in longer fire return intervals in subalpine forests and that these lengthened intervals increase competitive interactions between aspen and conifer species. We conducted a field and greenhouse study to compare photosynthesis, growth and defense responses of quaking aspen and subalpine fir regeneration under light reductions and shifts in soil chemistry that occur as conifers increase in dominance. The studies demonstrated that aspen regeneration was substantially more sensitive to light and soil resource limitations than that of subalpine fir. For aspen, light reductions and/or shifts in soil chemistry limited height growth, biomass gain, photosynthesis and the production of defense compounds (phenolic glycosides and condensed tannins). Biomass gain and phenolic glycoside concentrations were co-limited by light reduction and changes in soil chemistry. In contrast, subalpine fir seedlings tended to be more tolerant of low light conditions and showed no sensitivity to changes in soil chemistry. Unlike aspen, subalpine fir increased its root to shoot ratio on conifer soils, which may partially explain its maintenance of growth and defense. The results suggest that increasing dominance of conifers in subalpine forests alters light conditions and soil chemistry in a way that places greater physiological and growth constraints on aspen than subalpine fir, with a likely outcome being more successful recruitment of conifers and losses in aspen cover.

Capturing age-related changes in functional contrast sensitivity with decreasing light levels in monocular and binocular vision.

PubMed

Gillespie-Gallery, Hanna; Konstantakopoulou, Evgenia; Harlow, Jonathan A; Barbur, John L

2013-09-09

It is challenging to separate the effects of normal aging of the retina and visual pathways independently from optical factors, decreased retinal illuminance, and early stage disease. This study determined limits to describe the effect of light level on normal, age-related changes in monocular and binocular functional contrast sensitivity. We recruited 95 participants aged 20 to 85 years. Contrast thresholds for correct orientation discrimination of the gap in a Landolt C optotype were measured using a 4-alternative, forced-choice (4AFC) procedure at screen luminances from 34 to 0.12 cd/m(2) at the fovea and parafovea (0° and ±4°). Pupil size was measured continuously. The Health of the Retina index (HRindex) was computed to capture the loss of contrast sensitivity with decreasing light level. Participants were excluded if they exhibited performance outside the normal limits of interocular differences or HRindex values, or signs of ocular disease. Parafoveal contrast thresholds showed a steeper decline and higher correlation with age at the parafovea than the fovea. Of participants with clinical signs of ocular disease, 83% had HRindex values outside the normal limits. Binocular summation of contrast signals declined with age, independent of interocular differences. The HRindex worsens more rapidly with age at the parafovea, consistent with histologic findings of rod loss and its link to age-related degenerative disease of the retina. The HRindex and interocular differences could be used to screen for and separate the earliest stages of subclinical disease from changes caused by normal aging.

Differential Regulation of Duplicate Light-Dependent Protochlorophyllide Oxidoreductases in the Diatom Phaeodactylum tricornutum

PubMed Central

Hunsperger, Heather M.; Cattolico, Rose Ann

2016-01-01

Background Diatoms (Bacilliariophyceae) encode two light-dependent protochlorophyllide oxidoreductases (POR1 and POR2) that catalyze the penultimate step of chlorophyll biosynthesis in the light. Algae live in dynamic environments whose changing light levels induce photoacclimative metabolic shifts, including altered cellular chlorophyll levels. We hypothesized that the two POR proteins may be differentially adaptive under varying light conditions. Using the diatom Phaeodactylum tricornutum as a test system, differences in POR protein abundance and por gene expression were examined when this organism was grown on an alternating light:dark cycles at different irradiances; exposed to continuous light; and challenged by a significant decrease in light availability. Results For cultures maintained on a 12h light: 12h dark photoperiod at 200μE m−2 s−1 (200L/D), both por genes were up-regulated during the light and down-regulated in the dark, though por1 transcript abundance rose and fell earlier than that of por2. Little concordance occurred between por1 mRNA and POR1 protein abundance. In contrast, por2 mRNA and POR2 protein abundances followed similar diurnal patterns. When 200L/D P. tricornutum cultures were transferred to continuous light (200L/L), the diurnal regulatory pattern of por1 mRNA abundance but not of por2 was disrupted, and POR1 but not POR2 protein abundance dropped steeply. Under 1200μE m−2 s−1 (1200L/D), both por1 mRNA and POR1 protein abundance displayed diurnal oscillations. A compromised diel por2 mRNA response under 1200L/D did not impact the oscillation in POR2 abundance. When cells grown at 1200L/D were then shifted to 50μE m−2 s−1 (50L/D), por1 and por2 mRNA levels decreased swiftly but briefly upon light reduction. Thereafter, POR1 but not POR2 protein levels rose significantly in response to this light stepdown. Conclusion Given the sensitivity of diatom por1/POR1 to real-time light cues and adherence of por2/POR2 regulation to the diurnal cycle, we suggest that POR1 supports photoacclimation, whereas POR2 is the workhorse for daily chlorophyll synthesis. PMID:27367227

Light use efficiency of California redwood forest understory plants along a moisture gradient.

PubMed

Santiago, Louis S; Dawson, Todd E

2014-02-01

We investigated photosynthesis of five plant species growing in the understory at three sites (1,170-, 1,600- and 2,100-mm annual moisture inputs), along the geographical range of coastal California redwood forest, to determine whether greater inputs of rain and fog at northern sites enhance photosynthetic utilization of fluctuating light. Measurements of understory light environment and gas exchange were carried out to determine steady state and dynamic photosynthetic responses to light. Leaf area index ranged from 4.84 at the 2,100-mm site to 5.98 at the 1,170-mm site. Maximum rates of net photosynthesis and stomatal conductance (g) did not vary appreciably within species across sites. Photosynthetic induction after a change from low to high light was significantly greater in plants growing in lower light conditions regardless of site. Photosynthetic induction also increased with the rate of g in diffuse light, prior to the increase to saturating light levels. Post-illumination CO2 assimilation was the largest factor contributing to variation in C gain during simulated lightflecks. The duration of post-illumination photosynthetic activity, total CO2 assimilation per light received, and light use efficiency during simulated lightflecks increased significantly with moisture inputs in four out of five species. Increasing leaf N concentration with increasing moisture inputs in three out of five species, coupled with changes in leaf N isotopic composition with the onset of the summer fog season suggest that natural N deposition increases with rain and fog inputs and contributes to greater utilization of fluctuating light availability in coastal California redwood forests.

Cellular Antioxidant and Anti-Inflammatory Effects of Coffee Extracts with Different Roasting Levels.

PubMed

Jung, Soohan; Kim, Min Hyung; Park, Jae Hee; Jeong, Yoonhwa; Ko, Kwang Suk

2017-06-01

During roasting, major changes occur in the composition and physiological effects of coffee beans. In this study, in vitro antioxidant effects and anti-inflammatory effects of Coffea arabica green coffee extracts were investigated at different roasting levels corresponding to Light, Medium, City, and French roast. Total caffeine did not show huge difference according to roasting level, but total chlorogenic acid contents were higher in light roasted coffee extract than other roasted groups. In addition, light roasted coffee extract had the highest antioxidant activity in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. To determine the in vitro antioxidant property, coffee extracts were used to treat AML-12 cells. Intracellular glutathione (GSH) concentration and mRNA expression levels of genes related to GSH synthesis were negatively related to roasting levels. The anti-inflammatory effects of coffee extracts were investigated in lipopolysaccharide-treated RAW 264.7 macrophage cells. The cellular antioxidant activity of coffee extracts exhibited similar patterns as the AML-12 cells. The expression of mRNA for tumor necrosis factor-alpha and interleukin-6 was decreased in cells treated with the coffee extracts and the expression decreased with increasing roasting levels. These data suggest that coffee has physiological antioxidant and anti-inflammatory activities and these effects are negatively correlated with roasting levels in the cell models.

Circadian perinatal photoperiod has enduring effects on retinal dopamine and visual function.

PubMed

Jackson, Chad R; Capozzi, Megan; Dai, Heng; McMahon, Douglas G

2014-03-26

Visual system development depends on neural activity, driven by intrinsic and light-sensitive mechanisms. Here, we examined the effects on retinal function due to exposure to summer- and winter-like circadian light cycles during development and adulthood. Retinal light responses, visual behaviors, dopamine content, retinal morphology, and gene expression were assessed in mice reared in seasonal photoperiods consisting of light/dark cycles of 8:16, 16:8, and 12:12 h, respectively. Mice exposed to short, winter-like, light cycles showed enduring deficits in photopic retinal light responses and visual contrast sensitivity, but only transient changes were observed for scotopic measures. Dopamine levels were significantly lower in short photoperiod mice, and dopaminergic agonist treatment rescued the photopic light response deficits. Tyrosine hydroxylase and Early Growth Response factor-1 mRNA expression were reduced in short photoperiod retinas. Therefore, seasonal light cycles experienced during retinal development and maturation have lasting influence on retinal and visual function, likely through developmental programming of retinal dopamine.

Single bright light exposure decreases sweet taste threshold in healthy volunteers.

PubMed

Srivastava, Shrikant; Donaldson, Lucy F; Rai, Dheeraj; Melichar, Jan K; Potokar, John

2013-10-01

Bright light exposure can alter circulating serotonin levels, and alteration of available serotonin by acute selective serotonin reuptake inhibition significantly lowers sweet but not salt taste recognition thresholds. We tested the hypothesis that bright light exposure would increase sweet but not salt taste sensitivity in healthy adults. Fourteen healthy volunteers were exposed to bright (10,000 lux) and dim (<20 lux) light for 30 min each, in counterbalanced order. Measures of taste perception (salt and sweet) and mood were determined at baseline, and before and after each light exposure period. Recognition thresholds for sucrose were significantly lower after bright but not dim light exposure. Thresholds for salt were unaffected by either condition. There were no significant changes in taste acuity, intensity or pleasantness for both the taste modalities and on visual analogue scales (VASs) for mood, anxiety, sleepiness and alertness, under either light condition. Brief bright light exposure reduces sweet but not salt taste recognition thresholds in healthy humans.

Changes in dopamine and ZENK during suppression of myopia in chicks by intense illuminance.

PubMed

Lan, Weizhong; Yang, Zhikuan; Feldkaemper, Marita; Schaeffel, Frank

2016-04-01

High ambient illuminances have been found to slow the development of deprivation myopia in several animal models. Almost complete inhibition of myopia was observed in chickens when intermittent episodes of high illuminance were alternated with standard office illuminance (50% duty cycle, alternate periods of 1 min 15,000 lux and 1 min 500 lux, continued for 10 h per day), or when illuminances were increased to 40,000 lux. Since the mechanisms by which bright light suppresses myopia are poorly understood, we have studied the roles of two well-established signaling molecules in myopia, dopamine and ZENK, in the chicken. In line with previous studies, we found that retinal dopamine release (as reflected by vitreal DOPAC content) was severely reduced during development of deprivation myopia. We found that illuminance of 15,000 lux, provided by quartz-halogen lamps, partially rescued the drop in retinal dopamine release. The finding is in line with the assumption that dopamine is involved in the light-induced inhibition of myopia. No differences in vitreal DOPAC were found when bright light was provided continuously or with 1:1 min alternating exposure with 500 lux. As previously described by others, wearing diffusers suppressed the expression of ZENK protein in glucagonergic amacrine cells (GACs) but neither continuous nor 1:1 min alternating bright to normal light could rescue the suppression of ZENK in GACs. While it is well known that light increases global retinal ZENK mRNA and protein levels, the changes of ZENK protein induced specifically in GACs by diffuser wear appear independent of light levels. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mechanisms of low level light therapy

NASA Astrophysics Data System (ADS)

Hamblin, Michael R.; Demidova, Tatiana N.

2006-02-01

The use of low levels of visible or near infrared light for reducing pain, inflammation and edema, promoting healing of wounds, deeper tissues and nerves, and preventing tissue damage has been known for almost forty years since the invention of lasers. Originally thought to be a peculiar property of laser light (soft or cold lasers), the subject has now broadened to include photobiomodulation and photobiostimulation using non-coherent light. Despite many reports of positive findings from experiments conducted in vitro, in animal models and in randomized controlled clinical trials, LLLT remains controversial. This likely is due to two main reasons; firstly the biochemical mechanisms underlying the positive effects are incompletely understood, and secondly the complexity of rationally choosing amongst a large number of illumination parameters such as wavelength, fluence, power density, pulse structure and treatment timing has led to the publication of a number of negative studies as well as many positive ones. In particular a biphasic dose response has been frequently observed where low levels of light have a much better effect than higher levels. This introductory review will cover some of the proposed cellular chromophores responsible for the effect of visible light on mammalian cells, including cytochrome c oxidase (with absorption peaks in the near infrared) and photoactive porphyrins. Mitochondria are thought to be a likely site for the initial effects of light, leading to increased ATP production, modulation of reactive oxygen species and induction of transcription factors. These effects in turn lead to increased cell proliferation and migration (particularly by fibroblasts), modulation in levels of cytokines, growth factors and inflammatory mediators, and increased tissue oxygenation. The results of these biochemical and cellular changes in animals and patients include such benefits as increased healing in chronic wounds, improvements in sports injuries and carpal tunnel syndrome, pain reduction in arthritis and neuropathies, and amelioration of damage after heart attacks, stroke, nerve injury and retinal toxicity.

Depth-specific fluctuations of gene expression and protein abundance modulate the photophysiology in the seagrass Posidonia oceanica

NASA Astrophysics Data System (ADS)

Procaccini, Gabriele; Ruocco, Miriam; Marín-Guirao, Lázaro; Dattolo, Emanuela; Brunet, Christophe; D'Esposito, Daniela; Lauritano, Chiara; Mazzuca, Silvia; Serra, Ilia Anna; Bernardo, Letizia; Piro, Amalia; Beer, Sven; Björk, Mats; Gullström, Martin; Buapet, Pimchanok; Rasmusson, Lina M.; Felisberto, Paulo; Gobert, Sylvie; Runcie, John W.; Silva, João; Olivé, Irene; Costa, Monya M.; Barrote, Isabel; Santos, Rui

2017-02-01

Here we present the results of a multiple organizational level analysis conceived to identify acclimative/adaptive strategies exhibited by the seagrass Posidonia oceanica to the daily fluctuations in the light environment, at contrasting depths. We assessed changes in photophysiological parameters, leaf respiration, pigments, and protein and mRNA expression levels. The results show that the diel oscillations of P. oceanica photophysiological and respiratory responses were related to transcripts and proteins expression of the genes involved in those processes and that there was a response asynchrony between shallow and deep plants probably caused by the strong differences in the light environment. The photochemical pathway of energy use was more effective in shallow plants due to higher light availability, but these plants needed more investment in photoprotection and photorepair, requiring higher translation and protein synthesis than deep plants. The genetic differentiation between deep and shallow stands suggests the existence of locally adapted genotypes to contrasting light environments. The depth-specific diel rhythms of photosynthetic and respiratory processes, from molecular to physiological levels, must be considered in the management and conservation of these key coastal ecosystems.

Depth-specific fluctuations of gene expression and protein abundance modulate the photophysiology in the seagrass Posidonia oceanica

PubMed Central

Procaccini, Gabriele; Ruocco, Miriam; Marín-Guirao, Lázaro; Dattolo, Emanuela; Brunet, Christophe; D’Esposito, Daniela; Lauritano, Chiara; Mazzuca, Silvia; Serra, Ilia Anna; Bernardo, Letizia; Piro, Amalia; Beer, Sven; Björk, Mats; Gullström, Martin; Buapet, Pimchanok; Rasmusson, Lina M.; Felisberto, Paulo; Gobert, Sylvie; Runcie, John W.; Silva, João; Olivé, Irene; Costa, Monya M.; Barrote, Isabel; Santos, Rui

2017-01-01

Here we present the results of a multiple organizational level analysis conceived to identify acclimative/adaptive strategies exhibited by the seagrass Posidonia oceanica to the daily fluctuations in the light environment, at contrasting depths. We assessed changes in photophysiological parameters, leaf respiration, pigments, and protein and mRNA expression levels. The results show that the diel oscillations of P. oceanica photophysiological and respiratory responses were related to transcripts and proteins expression of the genes involved in those processes and that there was a response asynchrony between shallow and deep plants probably caused by the strong differences in the light environment. The photochemical pathway of energy use was more effective in shallow plants due to higher light availability, but these plants needed more investment in photoprotection and photorepair, requiring higher translation and protein synthesis than deep plants. The genetic differentiation between deep and shallow stands suggests the existence of locally adapted genotypes to contrasting light environments. The depth-specific diel rhythms of photosynthetic and respiratory processes, from molecular to physiological levels, must be considered in the management and conservation of these key coastal ecosystems. PMID:28211527

Gut microbiota composition is correlated to grid floor induced stress and behavior in the BALB/c mouse.

PubMed

Bangsgaard Bendtsen, Katja Maria; Krych, Lukasz; Sørensen, Dorte Bratbo; Pang, Wanyong; Nielsen, Dennis Sandris; Josefsen, Knud; Hansen, Lars H; Sørensen, Søren J; Hansen, Axel Kornerup

2012-01-01

Stress has profound influence on the gastro-intestinal tract, the immune system and the behavior of the animal. In this study, the correlation between gut microbiota composition determined by Denaturing Grade Gel Electrophoresis (DGGE) and tag-encoded 16S rRNA gene amplicon pyrosequencing (454/FLX) and behavior in the Tripletest (Elevated Plus Maze, Light/Dark Box, and Open Field combined), the Tail Suspension Test, and Burrowing in 28 female BALB/c mice exposed to two weeks of grid floor induced stress was investigated. Cytokine and glucose levels were measured at baseline, during and after exposure to grid floor. Stressing the mice clearly changed the cecal microbiota as determined by both DGGE and pyrosequencing. Odoribacter, Alistipes and an unclassified genus from the Coriobacteriaceae family increased significantly in the grid floor housed mice. Compared to baseline, the mice exposed to grid floor housing changed the amount of time spent in the Elevated Plus Maze, in the Light/Dark Box, and burrowing behavior. The grid floor housed mice had significantly longer immobility duration in the Tail Suspension Test and increased their number of immobility episodes from baseline. Significant correlations were found between GM composition and IL-1α, IFN-γ, closed arm entries of Elevated Plus Maze, total time in Elevated Plus Maze, time spent in Light/Dark Box, and time spent in the inner zone of the Open Field as well as total time in the Open Field. Significant correlations were found to the levels of Firmicutes, e.g. various species of Ruminococccaceae and Lachnospiraceae. No significant difference was found for the evaluated cytokines, except an overall decrease in levels from baseline to end. A significant lower level of blood glucose was found in the grid floor housed mice, whereas the HbA1c level was significantly higher. It is concluded that grid floor housing changes the GM composition, which seems to influence certain anxiety-related parameters.

The effect of reduced street lighting on road casualties and crime in England and Wales: controlled interrupted time series analysis.

PubMed

Steinbach, Rebecca; Perkins, Chloe; Tompson, Lisa; Johnson, Shane; Armstrong, Ben; Green, Judith; Grundy, Chris; Wilkinson, Paul; Edwards, Phil

2015-11-01

Many local authorities in England and Wales have reduced street lighting at night to save money and reduce carbon emissions. There is no evidence to date on whether these reductions impact on public health. We quantified the effect of 4 street lighting adaptation strategies (switch off, part-night lighting, dimming and white light) on casualties and crime in England and Wales. Observational study based on analysis of geographically coded police data on road traffic collisions and crime in 62 local authorities. Conditional Poisson models were used to analyse longitudinal changes in the counts of night-time collisions occurring on affected roads during 2000-2013, and crime within census Middle Super Output Areas during 2010-2013. Effect estimates were adjusted for regional temporal trends in casualties and crime. There was no evidence that any street lighting adaptation strategy was associated with a change in collisions at night. There was significant statistical heterogeneity in the effects on crime estimated at police force level. Overall, there was no evidence for an association between the aggregate count of crime and switch off (RR 0.11; 95% CI 0.01 to 2.75) or part-night lighting (RR 0.96; 95% CI 0.86 to 1.06). There was weak evidence for a reduction in the aggregate count of crime and dimming (RR 0.84; 95% CI 0.70 to 1.02) and white light (RR 0.89; 95% CI 0.77 to 1.03). This study found little evidence of harmful effects of switch off, part-night lighting, dimming, or changes to white light/LEDs on road collisions or crime in England and Wales. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Research on the speed of light transmission in a dual-frequency laser pumped single fiber with two directions

NASA Astrophysics Data System (ADS)

Qiu, Wei; Liu, Jianjun; Wang, Yuda; Yang, Yujing; Gao, Yuan; Lv, Pin; Jiang, Qiuli

2018-01-01

In this article a general theory of the coherent population oscillation effect in an erbium-doped fiber at room temperature is presented. We use dual pumping light waves with a simplified two-level system. Thus the time delay equations can be calculated from rate equations and the transmission equation. Using numerical simulation, in the case of dual-frequency pump light waves (1480 nm and 980 nm) with two directions, we analyze the influence of the pump power ratio on the group speed of light propagation. In addition, we compare slow light propagation with a single-pumping light and slow light propagation with a dual-pumping light at room temperature. The discussion shows that a larger time delay of slow light propagation can be obtained with a dual-frequency pumping laser. Compared to previous research methods, a dual-frequency laser pumped fiber with two directions is more controllable. Moreover, we conclude that the group velocity of light can be varied by changing the pump ratio.

Controlled Sol-Gel Transitions of a Thermoresponsive Polymer in a Photoswitchable Azobenzene Ionic Liquid as a Molecular Trigger.

PubMed

Wang, Caihong; Hashimoto, Kei; Tamate, Ryota; Kokubo, Hisashi; Watanabe, Masayoshi

2018-01-02

Producing ionic liquids (ILs) that function as molecular trigger for macroscopic change is a challenging issue. Photoisomerization of an azobenzene IL at the molecular level evokes a macroscopic response (light-controlled mechanical sol-gel transitions) for ABA triblock copolymer solutions. The A endblocks, poly(2-phenylethyl methacrylate), show a lower critical solution temperature in the IL mixture containing azobenzene, while the B midblock, poly(methyl methacrylate), is compatible with the mixture. In a concentrated polymer solution, different gelation temperatures were observed in it under dark and UV conditions. Light-controlled sol-gel transitions were achieved by a photoresponsive solubility change of the A endblocks upon photoisomerization of the azobenzene IL. Therefore, an azobenzene IL as a molecular switch can tune the self-assembly of a thermoresponsive polymer, leading to macroscopic light-controlled sol-gel transitions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photosynthesis and Ribulose 1,5-Bisphosphate Concentrations in Intact Leaves of Xanthium strumarium L. 1

PubMed Central

Mott, Keith A.; Jensen, Richard G.; O'Leary, James W.; Berry, Joseph A.

1984-01-01

The interacting effects of the rate of ribulose 1,5-bisphosphate (RuBP) regeneration and the rate of RuBP utilization as influenced by the amount and activation of RuBP carboxylase on photosynthesis and RuBP concentrations were resolved in experiments which examined the kinetics of the response of photosynthesis and RuBP concentrations after step changes from a rate-saturating to a rate-limiting light intensity in Xanthium strumarium. Because RuBP carboxylase requires several minutes to deactivate in vivo, it was possible to observe the effect of reducing the rate of RuBP regeneration on the RuBP concentration at constant enzyme activation state by sampling very soon after reducing the light intensity. Samples taken over longer time periods showed the effect of changes in enzyme activation at constant RuBP regeneration rate on RuBP concentration and photosynthetic rate. Within 15 s of lowering the light intensity from 1500 to 600 microEinsteins per square meter per second the RuBP concentration in the leaves dropped below the enzyme active site concentration, indicating that RuBP regeneration rate was limiting for photosynthesis. After longer intervals of time, the RuBP concentration in the leaf increased as the RuBP carboxylase assumed a new steady state activation level. No change in the rate of photosynthesis was observed during the interval that RuBP concentration increased. It is concluded that the rate of photosynthesis at the lower light intensity was limited by the rate of RuBP regeneration and that parallel changes in the activation of RuBP carboxylase occurred such that concentrations of RuBP at steady state were not altered by changes in light intensity. PMID:16663982

Photosynthesis and Ribulose 1,5-Bisphosphate Concentrations in Intact Leaves of Xanthium strumarium L.

PubMed

Mott, K A; Jensen, R G; O'leary, J W; Berry, J A

1984-12-01

The interacting effects of the rate of ribulose 1,5-bisphosphate (RuBP) regeneration and the rate of RuBP utilization as influenced by the amount and activation of RuBP carboxylase on photosynthesis and RuBP concentrations were resolved in experiments which examined the kinetics of the response of photosynthesis and RuBP concentrations after step changes from a rate-saturating to a rate-limiting light intensity in Xanthium strumarium. Because RuBP carboxylase requires several minutes to deactivate in vivo, it was possible to observe the effect of reducing the rate of RuBP regeneration on the RuBP concentration at constant enzyme activation state by sampling very soon after reducing the light intensity. Samples taken over longer time periods showed the effect of changes in enzyme activation at constant RuBP regeneration rate on RuBP concentration and photosynthetic rate. Within 15 s of lowering the light intensity from 1500 to 600 microEinsteins per square meter per second the RuBP concentration in the leaves dropped below the enzyme active site concentration, indicating that RuBP regeneration rate was limiting for photosynthesis. After longer intervals of time, the RuBP concentration in the leaf increased as the RuBP carboxylase assumed a new steady state activation level. No change in the rate of photosynthesis was observed during the interval that RuBP concentration increased. It is concluded that the rate of photosynthesis at the lower light intensity was limited by the rate of RuBP regeneration and that parallel changes in the activation of RuBP carboxylase occurred such that concentrations of RuBP at steady state were not altered by changes in light intensity.

Modelling of salad plants growth and physiological status in vitamin space greenhouse during lighting regime optimization

NASA Astrophysics Data System (ADS)

Konovalova, Irina; Berkovich, Yuliy A.; Smolyanina, Svetlana; Erokhin, Alexei; Yakovleva, Olga; Lapach, Sergij; Radchenko, Stanislav; Znamenskii, Artem; Tarakanov, Ivan

2016-07-01

The efficiency of the photoautotrophic element as part of bio-engineering life-support systems is determined substantially by lighting regime. The artificial light regime optimization complexity results from the wide range of plant physiological functions controlled by light: trophic, informative, biosynthetical, etc. An average photosynthetic photon flux density (PPFD), light spectral composition and pulsed light effects on the crop growth and plant physiological status were studied in the multivariate experiment, including 16 independent experiments in 3 replicates. Chinese cabbage plants (Brassica chinensis L.), cultivar Vesnianka, were grown during 24 days in a climatic chamber under white and red light-emitting diodes (LEDs): photoperiod 24 h, PPFD from 260 to 500 µM/(m ^{2}*s), red light share in the spectrum varying from 33% to 73%, pulsed (pulse period from 30 to 501 µs) and non-pulsed lighting. The regressions of plant photosynthetic and biochemical indexes as well as the crop specific productivity in response to the selected parameters of lighting regime were calculated. Developed models of crop net photosynthesis and dark respiration revealed the most intense gas exchange area corresponding to PPFD level 450 - 500 µM/(m ^{2}*s) with red light share in the spectrum about 60% and the pulse length 30 µs with a pulse period from 300 to 400 µs. Shoot dry weight increased monotonically in response to the increasing PPFD and changed depending on the pulse period under stabilized PPFD level. An increase in ascorbic acid content in the shoot biomass was revealed when increasing red light share in spectrum from 33% to 73%. The lighting regime optimization criterion (Q) was designed for the vitamin space greenhouse as the maximum of a crop yield square on its ascorbic acid concentration, divided by the light energy consumption. The regression model of optimization criterion was constructed based on the experimental data. The analysis of the model made it possible to determine the optimal lighting regime for the space greenhouse: PPFD level about 430 µ&M/(m ^{2}*s), red light share in the spectrum around 73%, non-pulsed lighting. At the same PPFD, Q-criterion value for the selected lighting regime was 1.5 times higher than under white LEDs, and slightly (about 15%) lower than under high-pressure sodium lamp light.

Red light and the sleep quality and endurance performance of Chinese female basketball players.

PubMed

Zhao, Jiexiu; Tian, Ye; Nie, Jinlei; Xu, Jincheng; Liu, Dongsen

2012-01-01

Good sleep is an important recovery method for prevention and treatment of overtraining in sport practice. Whether sleep is regulated by melatonin after red-light irradiation in athletes is unknown. To determine the effect of red light on sleep quality and endurance performance of Chinese female basketball players. Cohort study. Athletic training facility of the Chinese People's Liberation Army and research laboratory of the China Institute of Sport Science. Patients or Other Participants: Twenty athletes of the Chinese People's Liberation Army team (age = 18.60 6 3.60 years) took part in the study. Participants were divided into red-light treatment (n = 10) and placebo (n = 10) groups. The red-light treatment participants received 30 minutes of irradiation from a red-light therapy instrument every night for 14 days. The placebo group did not receive light illumination. The Pittsburgh Sleep Quality Index (PSQI) questionnaire was completed, serum melatonin was assessed, and 12-minute run was performed at preintervention (baseline) and postintervention (14 days). The 14-day whole-body irradiation with red-light treatment improved the sleep, serum melatonin level, and endurance performance of the elite female basketball players (P < .05). We found a correlation between changes in global Pittsburgh Sleep Quality Index and serum melatonin levels (r = -0.695, P = .006). Our study confirmed the effectiveness of body irradiation with red light in improving the quality of sleep of elite female basketball players and offered a nonpharmacologic and noninvasive therapy to prevent sleep disorders after training.

Impact of 'traffic-light' nutrition information on online food purchases in Australia.

PubMed

Sacks, Gary; Tikellis, Kim; Millar, Lynne; Swinburn, Boyd

2011-04-01

'Traffic-light' nutrition labelling has been proposed as a potential tool for improving the diet of the population, yet there has been little published research on the impact of traffic-light nutrition labelling on purchases in a supermarket environment. This study examined changes to online consumer food purchases in response to the introduction of traffic-light nutrition information (TLNI). The study consisted of a 10-week trial in a major Australian online grocery store. For the duration of the trial TLNI in the form of four colour-coded indicators representing the products' relative levels of fat, saturated fat, sugar and sodium content, was displayed on the product listing page of 53 of the retailer's own-brand products in five food categories (milk, bread, breakfast cereals, biscuits and frozen meals). The changes in sales before and after the introduction of TLNI were examined both within the intervention store and in a comparison store. TLNI had no discernible impact on sales, with the change in sales in the intervention store corresponding to changes in sales in the comparison store. No relationship was observed between changes in sales and the relative healthiness of products. This limited, short-term study found no evidence to support the notion that TLNI is likely to influence behaviour change. Further research is needed to examine the impact of providing TLNI in different contexts, for a longer duration and on more products, with and without complementary awareness and information campaigns. © 2011 The Authors. ANZJPH © 2011 Public Health Association of Australia.

Interactions between plant size and canopy openness influence vital rates and life-history tradeoffs in two neotropical understory herbs.

PubMed

Westerband, Andrea C; Horvitz, Carol C

2015-08-01

• For tropical forest understory plants, the ability to grow, survive, and reproduce is limited by the availability of light. The extent to which reproduction incurs a survival or growth cost may change with light availability, plant size, and adaptation to shade, and may vary among similar species.• We estimated size-specific rates of growth, survival, and reproduction (vital rates), for two neotropical understory herbs (order Zingiberales) in a premontane tropical rainforest in Costa Rica. During three annual censuses we monitored 1278 plants, measuring leaf area, number of inflorescences, and canopy openness. We fit regression models of all vital rates and evaluated them over a range of light levels. The best fitting models were selected using Akaike's Information Criterion.• All vital rates were significantly influenced by size in both species, but not always by light. Increasing light resulted in higher growth and a higher probability of reproduction in both species, but lower survival in one species. Both species grew at small sizes but shrank at larger sizes. The size at which shrinkage began differed among species and light environments. Vital rates of large individuals were more sensitive to changes in light than small individuals.• Increasing light does not always positively influence vital rates; the extent to which light affects vital rates depends on plant size. Differences among species in their abilities to thrive under different light conditions and thus occupy distinct niches may contribute to the maintenance of species diversity. © 2015 Botanical Society of America, Inc.

Suppression of melatonin secretion by bright light in seasonal affective disorder.

PubMed

Partonen, T; Vakkuri, O; Lönnqvist, J

1997-09-15

Eleven patients with winter seasonal affective disorder and 10 healthy controls were exposed to light of 3300 lux for 5 min and for 1 hour respectively on consecutive evenings at 22:00 hours during winter and summer. In the winter, the measurements were undertaken both before and after the treatment with bright light for 2 weeks. In the summer, there was no treatment. Melatonin concentration in saliva and subjective sleepiness were measured at 22:00 and 23:00 hours on each test. There was no significant difference in the suppression of melatonin in response to the light tests between the patients and the controls. Exposure to light reduced the level of subjective sleepiness more among the patients compared to the control subjects. This reduction was not associated with the change in melatonin secretion nor the improvement in depressive symptoms.

Is the use of underwater polarized light by fish restricted to crepuscular time periods?

PubMed

Novales Flamarique, I; Hawryshyn, C W

1997-04-01

We measured the spectral distributions of the underwater total and polarized light fields in the upper photic zone of meso-eutrophic waters (i.e., blue-green waters containing medium to high chlorophyll a concentrations). Per cent polarization levels during the day were always lower than 40%, but at crepuscular times these values could increase to 67%. A corresponding change occurred in the spectral distribution, with proportionately more shorter wavelength photons contributing to the total spectrum during crepuscular periods. Electrophysiological recordings from the optic nerve of rainbow trout subjected to light stimuli of varying polarization percentages show that the animal's threshold for detecting polarized light is between 63 and 72%. These physiological findings suggest that the use of water-induced polarized light cues by rainbow trout and similar percomorph fish should be restricted to crepuscular time periods.

Adaptive lighting controllers using smart sensors

NASA Astrophysics Data System (ADS)

Papantoniou, Sotiris; Kolokotsa, Denia; Kalaitzakis, Kostas; Cesarini, Davide Nardi; Cubi, Eduard; Cristalli, Cristina

2016-07-01

The aim of this paper is to present an advanced controller for artificial lights evaluated in several rooms in two European Hospitals located in Chania, Greece and Ancona, Italy. Fuzzy techniques have been used for the architecture of the controller. The energy efficiency of the controllers has been calculated by running the controller coupled with validated models of the RADIANCE back-wards ray tracing software. The input of the controller is the difference between the current illuminance value and the desired one, while the output is the change of the light level that should be applied in the artificial lights. Simulation results indicate significant energy saving potentials. Energy saving potential is calculated from the comparison of the current use of the artificial lights by the users and the proposed one. All simulation work has been conducted using Matlab and RADIANCE environment.

Ground based remote sensing and physiological measurements provide novel insights into canopy photosynthetic optimization in arctic shrubs

NASA Astrophysics Data System (ADS)

Magney, T. S.; Griffin, K. L.; Boelman, N.; Eitel, J.; Greaves, H.; Prager, C.; Logan, B.; Oliver, R.; Fortin, L.; Vierling, L. A.

2014-12-01

Because changes in vegetation structure and function in the Arctic are rapid and highly dynamic phenomena, efforts to understand the C balance of the tundra require repeatable, objective, and accurate remote sensing methods for estimating aboveground C pools and fluxes over large areas. A key challenge addressing the modelling of aboveground C is to utilize process-level information from fine-scale studies. Utilizing information obtained from high resolution remote sensing systems could help to better understand the C source/sink strength of the tundra, which will in part depend on changes in photosynthesis resulting from the partitioning of photosynthetic machinery within and among deciduous shrub canopies. Terrestrial LiDAR and passive hyperspectral remote sensing measurements offer an effective, repeatable, and scalable method to understand photosynthetic performance and partitioning at the canopy scale previously unexplored in arctic systems. Using a 3-D shrub canopy model derived from LiDAR, we quantified the light regime of leaves within shrub canopies to gain a better understanding of how light interception varies in response to the Arctic's complex radiation regime. This information was then coupled with pigment sampling (i.e., xanthophylls, and Chl a/b) to evaluate the optimization of foliage photosynthetic capacity within shrub canopies due to light availability. In addition, a lab experiment was performed to validate evidence of canopy level optimization via gradients of light intensity and leaf light environment. For this, hyperspectral reflectance (photochemical reflectance index (PRI)), and solar induced fluorescence (SIF)) was collected in conjunction with destructive pigment samples (xanthophylls) and chlorophyll fluorescence measurements in both sunlit and shaded canopy positions.

Light accelerates plant responses to warming.

PubMed

De Frenne, Pieter; Rodríguez-Sánchez, Francisco; De Schrijver, An; Coomes, David A; Hermy, Martin; Vangansbeke, Pieter; Verheyen, Kris

2015-08-17

Competition for light has profound effects on plant performance in virtually all terrestrial ecosystems. Nowhere is this more evident than in forests, where trees create environmental heterogeneity that shapes the dynamics of forest-floor communities(1-3). Observational evidence suggests that biotic responses to both anthropogenic global warming and nitrogen pollution may be attenuated by the shading effects of trees and shrubs(4-9). Here we show experimentally that tree shade is slowing down changes in below-canopy communities due to warming. We manipulated levels of photosynthetically active radiation, temperature and nitrogen, alone and in combination, in a temperate forest understorey over a 3-year period, and monitored the composition of the understorey community. Light addition, but not nitrogen enrichment, accelerated directional plant community responses to warming, increasing the dominance of warmth-preferring taxa over cold-tolerant plants (a process described as thermophilization(6,10-12)). Tall, competitive plants took greatest advantage of the combination of elevated temperature and light. Warming of the forest floor did not result in strong community thermophilization unless light was also increased. Our findings suggest that the maintenance of locally closed canopy conditions could reduce, at least temporarily, warming-induced changes in forest floor plant communities.

Perception of biological motion from size-invariant body representations.

PubMed

Lappe, Markus; Wittinghofer, Karin; de Lussanet, Marc H E

2015-01-01

The visual recognition of action is one of the socially most important and computationally demanding capacities of the human visual system. It combines visual shape recognition with complex non-rigid motion perception. Action presented as a point-light animation is a striking visual experience for anyone who sees it for the first time. Information about the shape and posture of the human body is sparse in point-light animations, but it is essential for action recognition. In the posturo-temporal filter model of biological motion perception posture information is picked up by visual neurons tuned to the form of the human body before body motion is calculated. We tested whether point-light stimuli are processed through posture recognition of the human body form by using a typical feature of form recognition, namely size invariance. We constructed a point-light stimulus that can only be perceived through a size-invariant mechanism. This stimulus changes rapidly in size from one image to the next. It thus disrupts continuity of early visuo-spatial properties but maintains continuity of the body posture representation. Despite this massive manipulation at the visuo-spatial level, size-changing point-light figures are spontaneously recognized by naive observers, and support discrimination of human body motion.

Method and apparatus for thermal management of vehicle exhaust systems

DOEpatents

Benson, David K.; Potter, Thomas F.

1995-01-01

A catalytic converter is surrounded by variable conductance insulation for maintaining the operating temperature of the catalytic converter at an optimum level, for inhibiting heat loss when raising catalytic converter temperature to light-off temperature, for storing excess heat to maintain or accelerate reaching light-off temperature, and for conducting excess heat away from the catalytic converter after reaching light-off temperature. The variable conductance insulation includes vacuum gas control and metal-to-metal thermal shunt mechanisms. Radial and axial shielding inhibits radiation and convection heat loss. Thermal storage media includes phase change material, and heat exchanger chambers and fluids carry heat to and from the catalytic converter.

Alternative Line Coding Scheme with Fixed Dimming for Visible Light Communication

NASA Astrophysics Data System (ADS)

Niaz, M. T.; Imdad, F.; Kim, H. S.

2017-01-01

An alternative line coding scheme called fixed-dimming on/off keying (FD-OOK) is proposed for visible-light communication (VLC). FD-OOK reduces the flickering caused by a VLC transmitter and can maintain a 50% dimming level. Simple encoder and decoder are proposed which generates codes where the number of bits representing one is same as the number of bits representing zero. By keeping the number of ones and zeros equal the change in the brightness of lighting may be minimized and kept constant at 50%, thereby reducing the flickering in VLC. The performance of FD-OOK is analysed with two parameters: the spectral efficiency and power requirement.

An Integrated, Evidence-Based Approach to Transitioning to Operations: Specifications for Future Replacement Lights on ISS

NASA Technical Reports Server (NTRS)

Leveton, Lauren; Brainard, George; Whitmire, Alexandra; Kubey, Alan; Maida, Jim; Bowen, Charles; Johnston, Smith

2010-01-01

The International Space Station (ISS) currently uses General Luminaire Assemblies (GLAs) as its primary light source. These GLAs are composed of fluorescent lighting and are integrated into the electrical system on Station. Seventy seven of these units are distributed throughout the vehicle, and many of the lights, having reached their lifespan, are no longer functional; while backup panels are available on orbit, it is anticipated that the supplies of fluorescents on the station will be exhausted by 2015. The ISS vehicle office is therefore preparing to replace all of the GLAs, with Solid State Light Assemblies (SSLAs) composed of white Light Emitting Diodes (LEDs). In the Spring of 2010, an announcement for the replacement lights was released. The announcement specified that proposed lighting systems should use LED technology, given certain power draw restrictions and no changes to how the lights are currently controlled (a central on/off switch per node, and a dial to turn on/off and increase brightness on each lighting unit). The replacement lights are to follow current specifications for brightness levels (lux) and color temperature (degrees Kelvin, or K). Reportedly, the lighting on orbit is dim and suboptimal. The average brightness of the lights (given all lights within a node are operational) is 291 lux; by comparison, recommended office lighting ranges from 200 to 500 lux, and daylight ranges on a typical overcast day, consists of 10,000 to 25,000 lux. Representatives from NASA Behavioral Health and Performance Element (BHP) and Human Factors and Habitability identified that maintaining current brightness levels limits visual acuity, work space, and the use of light as a countermeasure for improving circadian entrainment, hastening phase shifting, evoking acute alertness and enhancing performance. Revised lighting specifications are therefore needed to optimize the replacement lights for the ISS.

Thyrotropin-releasing hormone-like material in the rat retina: changes due to environmental lighting.

PubMed Central

Schaeffer, J M; Brownstein, M J; Axelrod, J

1977-01-01

Material reacting with an antibody to thyrotropin-releasing hormone (TRH) has been found to be present in the rat retina. The compound present in the retina cochromatographed with authentic TRH and most of its activity was lost when incubated with pyroglutamate aminopeptidase (L-pyroglutamyl-peptide hydrolase, EC 3.4.11.8), an enzyme that degrades TRH. The TRH-like activity in the rat retina was low during the night and high during the day. There was a 4-hr lag period after the lights were turned on before peak TRH levels were attained. A decrease in TRH was seen after 2 hr of darkness and the level of TRH was lowest after 4 hr of darkness. Retinal TRH is elevated by environmental lighting regardless of the time of the day. These findings suggest that TRH may be involved in retinal photorecptive mechanisms. PMID:20629

Sleep and Behavior in Cross-Fostering Rats: Developmental and Sex Aspects.

PubMed

Santangeli, Olena; Lehtikuja, Henna; Palomäki, Eeva; Wigren, Henna-Kaisa; Paunio, Tiina; Porkka-Heiskanen, Tarja

2016-12-01

Adverse early-life events induce behavioral psychopathologies and sleep changes in adulthood. In order to understand the molecular level mechanisms by which the maltreatment modifies sleep, valid animal models are needed. Changing pups between mothers at early age (cross-fostering) may satisfyingly model adverse events in human childhood. Cross-fostering (CF) was used to model mild early-life stress in male and female Wistar rats. Behavior and BDNF gene expression in the basal forebrain (BF), cortex, and hypothalamus were assessed during adolescence and adulthood. Spontaneous sleep, sleep homeostasis, and BF extracellular adenosine levels were assessed in adulthood. CF rats demonstrated increased number of REM sleep onsets in light and dark periods of the day. Total REM and NREM sleep duration was also increased during the light period. While sleep homeostasis was not severely affected, basal level of adenosine in the BF of both male and female CF rats was lower than in controls. CF did not lead to considerable changes in behavior. Even when the consequences of adverse early-life events are not observed in tests for anxiety and depression, they leave a molecular mark in the brain, which can act as a vulnerability factor for psychopathologies in later life. Sleep is a sensitive indicator for even mild early-life stress. © 2016 Associated Professional Sleep Societies, LLC.

Barrier island community change: What controls it?

NASA Astrophysics Data System (ADS)

Dows, B.; Young, D.; Zinnert, J.

2014-12-01

Conversion from grassland to woody dominated communities has been observed globally. In recent decades, this pattern has been observed in coastal communities along the mid-Atlantic U.S. In coastal environments, a suite of biotic and abiotic factors interact as filters to determine plant community structure and distribution. Microclimatic conditions: soil and air temperature, soil moisture and salinity, and light attenuation under grass cover were measured across a grassland-woody encroachment gradient on a Virginia barrier island; to identify the primary factors that mediate this change. Woody establishment was associated with moderately dense (2200 shoots/m2) grass cover, but reduced at high (> 6200 shoots/ m2) and low (< 1250 shoots/ m2) densities. Moderately dense grass cover reduced light attenuation (82.50 % reduction) to sufficiently reduce soil temperature thereby limiting soil moisture evaporation. However, high grass density reduced light attenuation (98.7 % reduction) enough to inhibit establishment of woody species; whereas low grass density attenuated much less light (48.7 % reduction) which allowed for greater soil moisture evaporation. Soil salinity was dynamic as rainfall, tidal inundation, and sea spray produce spatiotemporal variation throughout the barrier island landscape. The importance of light and temperature were compounded as they also indirectly affect soil salinity via their affects on soil moisture. Determining how these biotic and abiotic factors relate to sea level rise and climate change will improve understanding coastal community response as global changes proceed. Understanding how community shifts affect ecosystem function and their potential to affect adjacent systems will also improve predictive ability of coastal ecosystem responses.

Simultaneous regulation of antenna size and photosystem I/II stoichiometry in Arabidopsis thaliana.

PubMed

Jia, Ting; Ito, Hisashi; Tanaka, Ayumi

2016-11-01

The photosystem I/II ratio increased when antenna size was enlarged by transient induction of CAO in chlorophyll b -less mutants, thus indicating simultaneous regulation of antenna size and photosystem I/II stoichiometry. Regulation of antenna size and photosystem I/II stoichiometry is an indispensable strategy for plants to acclimate to changes to light environments. When plants grown in high-light conditions are transferred to low-light conditions, the peripheral antennae of photosystems are enlarged. A change in the photosystem I/II ratio is also observed under the same light conditions. However, our knowledge of the correlation between antenna size modulation and variation in photosystem I/II stoichiometry remains limited. In this study, chlorophyll a oxygenase was transiently induced in Arabidopsis thaliana chlorophyll b-less mutants, ch1-1, to alter the antenna size without changing environmental conditions. In addition to the accumulation of chlorophyll b, the levels of the peripheral antenna complexes of both photosystems gradually increased, and these were assembled to the core antenna of both photosystems. However, the antenna size of photosystem II was greater than that of photosystem I. Immunoblot analysis of core antenna proteins showed that the number of photosystem I increased, but not that of photosystem II, resulting in an increase in the photosystem I/II ratio. These results clearly indicate that antenna size adjustment was coupled with changes in photosystem I/II stoichiometry. Based on these results, the physiological importance of simultaneous regulation of antenna size and photosystem I/II stoichiometry is discussed in relation to acclimation to light conditions.

Colour perception with changes in levels of illumination

NASA Astrophysics Data System (ADS)

Baah, Kwame F.; Green, Phil; Pointer, Michael

2012-01-01

The perceived colour of a stimulus depends on the conditions under which it is viewed. For colours employed as an important cue or identifier, such as signage and brand colours, colour reproduction tolerances are critically important. Typically, such stimuli would be judged using a known level of illumination but, in the target environment, the level of illumination used to view the samples may be entirely different. The effect of changes in the viewing condition on the perceptibility and acceptability of small colour differences should be understood when such tolerances and associated viewing conditions, are specified. A series of psychophysical experiments was conducted to determine whether changes in illumination level significantly alter acceptability and perceptibility thresholds of uniform colour stimuli. It was found that perceived colour discrimination thresholds varied by up to 2.0 ΔE00. For the perceptual correlate of hue however, this value could be of significance if the accepted error of colour difference was at the threshold, thereby yielding the possibility of rejection with changes in illumination level. Lightness and chroma on the other hand, exhibited greater tolerance and were less likely to be rejected with illuminance changes.

Coordinate changes of myosin light and heavy chain isoforms during forced fiber type transitions in rabbit muscle.

PubMed

Leeuw, T; Pette, D

1996-01-01

Skeletal muscle fibers are versatile entities, capable of changing their phenotype in response to altered functional demands. In the present study, fast-to-slow fiber type transitions were induced in rabbit tibialis anterior (fA) muscles by chronic low-frequency stimulation (CLFS). The time course of changes in relative protein concentrations of fast and slow myosin light chain (MLC) isoforms and changes in their relative synthesis rates by in vivo labeling with [35S]methionine were followed during stimulation periods of up to 60 days. Generally, relative synthesis rates and protein concentrations changed in parallel; i.e., fast isoforms decreased and slow isoforms increased. MLC3f, however, which turns over at a higher rate than the other light chains, exhibited a conspicuous discrepancy between a markedly reduced relative synthesis but only a moderate decrease in protein amount during the initial 2 weeks of CLFS. Apparently, MLC3f is regulated independent of MLC1f, with protein degradation playing an important role in its regulation. The exchange of fast MLC isoforms with their slow counterparts seemed to correspond to the ultimate fast-to-slow (MHCIIa-->MHCI) transition at the MHC level. However, due to an earlier onset of the fast-to-slow transition of the regulatory light chain and the delayed fast-to-slow exchange of the alkali light chains, a spectrum of hybrid isomyosins composed of fast and slow light and heavy chains must have existed transiently in transforming fibers. Such hybrid isomyosins appeared to be restricted to MHCIIa- and MHCI-based combinations. In conclusion, fiber type specific programs that normally coordinate the expression of myofibrillar protein isoforms seem to be maintained during fiber type transitions. Possible differences in post-transcriptional regulation may result in the transient accumulation of atypical combinations of fast and slow MLC and MHC isoforms, giving rise to the appearance of hybrid fibers under the conditions of forced fiber type conversion.

Mapping lightscapes: spatial patterning of artificial lighting in an urban landscape.

PubMed

Hale, James D; Davies, Gemma; Fairbrass, Alison J; Matthews, Thomas J; Rogers, Christopher D F; Sadler, Jon P

2013-01-01

Artificial lighting is strongly associated with urbanisation and is increasing in its extent, brightness and spectral range. Changes in urban lighting have both positive and negative effects on city performance, yet little is known about how its character and magnitude vary across the urban landscape. A major barrier to related research, planning and governance has been the lack of lighting data at the city extent, particularly at a fine spatial resolution. Our aims were therefore to capture such data using aerial night photography and to undertake a case study of urban lighting. We present the finest scale multi-spectral lighting dataset available for an entire city and explore how lighting metrics vary with built density and land-use. We found positive relationships between artificial lighting indicators and built density at coarse spatial scales, whilst at a local level lighting varied with land-use. Manufacturing and housing are the primary land-use zones responsible for the city's brightly lit areas, yet manufacturing sites are relatively rare within the city. Our data suggests that efforts to address light pollution should broaden their focus from residential street lighting to include security lighting within manufacturing areas.

Mapping Lightscapes: Spatial Patterning of Artificial Lighting in an Urban Landscape

PubMed Central

Hale, James D.; Davies, Gemma; Fairbrass, Alison J.; Matthews, Thomas J.; Rogers, Christopher D. F.; Sadler, Jon P.

2013-01-01

Artificial lighting is strongly associated with urbanisation and is increasing in its extent, brightness and spectral range. Changes in urban lighting have both positive and negative effects on city performance, yet little is known about how its character and magnitude vary across the urban landscape. A major barrier to related research, planning and governance has been the lack of lighting data at the city extent, particularly at a fine spatial resolution. Our aims were therefore to capture such data using aerial night photography and to undertake a case study of urban lighting. We present the finest scale multi-spectral lighting dataset available for an entire city and explore how lighting metrics vary with built density and land-use. We found positive relationships between artificial lighting indicators and built density at coarse spatial scales, whilst at a local level lighting varied with land-use. Manufacturing and housing are the primary land-use zones responsible for the city’s brightly lit areas, yet manufacturing sites are relatively rare within the city. Our data suggests that efforts to address light pollution should broaden their focus from residential street lighting to include security lighting within manufacturing areas. PMID:23671566

Optogenetic Manipulation of Cyclic Di-GMP (c-di-GMP) Levels Reveals the Role of c-di-GMP in Regulating Aerotaxis Receptor Activity in Azospirillum brasilense.

PubMed

O'Neal, Lindsey; Ryu, Min-Hyung; Gomelsky, Mark; Alexandre, Gladys

2017-09-15

Bacterial chemotaxis receptors provide the sensory inputs that inform the direction of navigation in changing environments. Recently, we described the bacterial second messenger cyclic di-GMP (c-di-GMP) as a novel regulator of a subclass of chemotaxis receptors. In Azospirillum brasilense , c-di-GMP binds to a chemotaxis receptor, Tlp1, and modulates its signaling function during aerotaxis. Here, we further characterize the role of c-di-GMP in aerotaxis using a novel dichromatic optogenetic system engineered for manipulating intracellular c-di-GMP levels in real time. This system comprises a red/near-infrared-light-regulated diguanylate cyclase and a blue-light-regulated c-di-GMP phosphodiesterase. It allows the generation of transient changes in intracellular c-di-GMP concentrations within seconds of irradiation with appropriate light, which is compatible with the time scale of chemotaxis signaling. We provide experimental evidence that binding of c-di-GMP to the Tlp1 receptor activates its signaling function during aerotaxis, which supports the role of transient changes in c-di-GMP levels as a means of adjusting the response of A. brasilense to oxygen gradients. We also show that intracellular c-di-GMP levels in A. brasilense change with carbon metabolism. Our data support a model whereby c-di-GMP functions to imprint chemotaxis receptors with a record of recent metabolic experience, to adjust their contribution to the signaling output, thus allowing the cells to continually fine-tune chemotaxis sensory perception to their metabolic state. IMPORTANCE Motile bacteria use chemotaxis to change swimming direction in response to changes in environmental conditions. Chemotaxis receptors sense environmental signals and relay sensory information to the chemotaxis machinery, which ultimately controls the swimming pattern of cells. In bacteria studied to date, differential methylation has been known as a mechanism to control the activity of chemotaxis receptors and modulates their contribution to the overall chemotaxis response. Here, we used an optogenetic system to perturb intracellular concentrations of the bacterial second messenger c-di-GMP to show that in some chemotaxis receptors, c-di-GMP functions in a similar feedback loop to connect the metabolic status of the cells to the sensory activity of chemotaxis receptors. Copyright © 2017 American Society for Microbiology.

Optogenetic Manipulation of Cyclic Di-GMP (c-di-GMP) Levels Reveals the Role of c-di-GMP in Regulating Aerotaxis Receptor Activity in Azospirillum brasilense

PubMed Central

O'Neal, Lindsey; Ryu, Min-Hyung; Gomelsky, Mark

2017-01-01

ABSTRACT Bacterial chemotaxis receptors provide the sensory inputs that inform the direction of navigation in changing environments. Recently, we described the bacterial second messenger cyclic di-GMP (c-di-GMP) as a novel regulator of a subclass of chemotaxis receptors. In Azospirillum brasilense, c-di-GMP binds to a chemotaxis receptor, Tlp1, and modulates its signaling function during aerotaxis. Here, we further characterize the role of c-di-GMP in aerotaxis using a novel dichromatic optogenetic system engineered for manipulating intracellular c-di-GMP levels in real time. This system comprises a red/near-infrared-light-regulated diguanylate cyclase and a blue-light-regulated c-di-GMP phosphodiesterase. It allows the generation of transient changes in intracellular c-di-GMP concentrations within seconds of irradiation with appropriate light, which is compatible with the time scale of chemotaxis signaling. We provide experimental evidence that binding of c-di-GMP to the Tlp1 receptor activates its signaling function during aerotaxis, which supports the role of transient changes in c-di-GMP levels as a means of adjusting the response of A. brasilense to oxygen gradients. We also show that intracellular c-di-GMP levels in A. brasilense change with carbon metabolism. Our data support a model whereby c-di-GMP functions to imprint chemotaxis receptors with a record of recent metabolic experience, to adjust their contribution to the signaling output, thus allowing the cells to continually fine-tune chemotaxis sensory perception to their metabolic state. IMPORTANCE Motile bacteria use chemotaxis to change swimming direction in response to changes in environmental conditions. Chemotaxis receptors sense environmental signals and relay sensory information to the chemotaxis machinery, which ultimately controls the swimming pattern of cells. In bacteria studied to date, differential methylation has been known as a mechanism to control the activity of chemotaxis receptors and modulates their contribution to the overall chemotaxis response. Here, we used an optogenetic system to perturb intracellular concentrations of the bacterial second messenger c-di-GMP to show that in some chemotaxis receptors, c-di-GMP functions in a similar feedback loop to connect the metabolic status of the cells to the sensory activity of chemotaxis receptors. PMID:28264994

The light cycle controls the hatching rhythm in Bombyx mori via negative feedback loop of the circadian oscillator.

PubMed

Tao, Hui; Li, Xue; Qiu, Jian-Feng; Liu, Heng-Jiang; Zhang, Da-Yan; Chu, Feng; Sima, Yanghu; Xu, Shi-Qing

2017-10-01

Hatching behavior is a key target in silkworm (Bombyx mori) rearing, especially for the control of Lepidoptera pests. According to previous research, hatching rhythms appear to be controlled by a clock mechanism that restricts or "gates" hatching to a particular time. However, the underlying mechanism remains elusive. Under 12-h light:12-h dark photoperiod (LD) conditions, the transcriptional levels of the chitinase5 (Cht5) and hatching enzyme-like (Hel) genes, as well as the enzymatic activities of their gene products, oscillated in time with ambient light cycles, as did the transcriptional levels of the cryptochrome 1, cryptochrome 2, period (per), and timeless genes, which are key components of the negative feedback loop of the circadian rhythm. These changes were related to the expression profile of the ecdysteroid receptor gene and the hatching behavior of B. mori eggs. However, under continuous light or dark conditions, the hatching behavior, the expression levels of Cht5 and Hel, as well as the enzymatic activities of their gene products, were not synchronized unlike under LD conditions. In addition, immunohistochemistry experiments showed that light promoted the translocation of PER from the cytoplasm to the nucleus. In conclusion, LD cycles regulate the hatching rhythm of B. mori via negative feedback loop of the circadian oscillator. © 2017 Wiley Periodicals, Inc.

Environmental light color affects the stress response of Nile tilapia.

PubMed

Maia, Caroline Marques; Volpato, Gilson Luiz

2013-02-01

We investigated the effects of environmental light colors (blue, yellow and white) on the stress responses (measured by changes in ventilatory frequency - VF) of Nile tilapia to confinement. After 7 days of light treatment, the VF was similar for fish in each color. On the 8th day, fish were confined for 15 min. After release, the post-confinement VF was measured six times (first period: 0, 2 and 4 min; second period: 6, 8 and 10 min). Irrespective of the light color treatment, confinement increased the VF to higher levels during the first post-confinement period than during the second one. When color was analyzed, irrespective of time, fish under white light increased their VF post-confinement, and blue light prevented this effect. We conclude that blue light is the preferred color for Nile tilapia in terms of reducing stress. This finding is in contrast to previous choice test studies that indicated that yellow is their preferred color. Copyright © 2012 Elsevier GmbH. All rights reserved.

Electromagnetically induced transparency and nonlinear pulse propagation in a combined tripod and Λ atom-light coupling scheme

NASA Astrophysics Data System (ADS)

Hamedi, H. R.; Ruseckas, J.; Juzeliūnas, G.

2017-09-01

We consider propagation of a probe pulse in an atomic medium characterized by a combined tripod and Lambda (Λ) atom-light coupling scheme. The scheme involves three atomic ground states coupled to two excited states by five light fields. It is demonstrated that dark states can be formed for such an atom-light coupling. This is essential for formation of the electromagnetically induced transparency (EIT) and slow light. In the limiting cases the scheme reduces to conventional Λ- or N-type atom-light couplings providing the EIT or absorption, respectively. Thus, the atomic system can experience a transition from the EIT to the absorption by changing the amplitudes or phases of control lasers. Subsequently the scheme is employed to analyze the nonlinear pulse propagation using the coupled Maxwell-Bloch equations. It is shown that a generation of stable slow light optical solitons is possible in such a five-level combined tripod and Λ atomic system.

Development of a New Departure Aversion Standard for Light Aircraft

NASA Technical Reports Server (NTRS)

Borer, Nicholas K.

2017-01-01

The Federal Aviation Administration (FAA) and European Aviation Safety Agency (EASA) have recently established new light aircraft certification rules that introduce significant changes to the current regulations. The changes include moving from prescriptive design requirements to performance-based standards, transferring many of the acceptable means of compliance out of the rules and into consensus standards. In addition, the FAA/EASA rules change the performance requirements associated with some of the more salient safety issues regarding light aircraft. One significant change is the elimination of spin recovery demonstration. The new rules now call for enhanced stall warning and aircraft handling characteristics that demonstrate resistance to inadvertent departure from controlled flight. The means of compliance with these changes in a safe, cost-effective manner is a challenging problem. This paper discusses existing approaches to reducing the likelihood of departure from controlled flight and introduces a new approach, dubbed Departure Aversion, which allows applicants to tailor the amount of departure resistance, stall warning, and enhanced safety equipment to meet the new proposed rules. The Departure Aversion approach gives applicants the freedom to select the most cost-effective portfolio for their design, while meeting the safety intent of the new rules, by ensuring that any combination of the selected approaches will be at a higher equivalent level of safety than today's status quo.

Elymus repens biomass allocation and acquisition as affected by light and nutrient supply and companion crop competition.

PubMed

Ringselle, Björn; Prieto-Ruiz, Inés; Andersson, Lars; Aronsson, Helena; Bergkvist, Göran

2017-02-01

Competitive crops are a central component of resource-efficient weed control, especially for problematic perennial weeds such as Elymus repens Competition not only reduces total weed biomass, but denial of resources can also change the allocation pattern - potentially away from the underground storage organs that make perennial weeds difficult to control. Thus, the competition mode of crops may be an important component in the design of resource-efficient cropping systems. Our aim was to determine how competition from companion crops with different modes of competition affect E. repens biomass acquisition and allocation and discuss that in relation to how E. repens responds to different levels of light and nutrient supply. Greenhouse experiments were conducted with E. repens growing in interspecific competition with increasing density of perennial ryegrass or red clover, or growing at three levels of both light and nutrient supply. Elymus repens total biomass decreased with increasing biomass of the companion crop and the rate of decrease was higher with red clover than with perennial ryegrass, particularly for E. repens rhizome biomass. A reduced nutrient supply shifted E. repens allocation towards below-ground biomass while a reduced light supply shifted it towards shoot biomass. Red clover caused no change in E. repens allocation pattern, while ryegrass mostly shifted the allocation towards below-ground biomass, but the change was not correlated with ryegrass biomass. The companion crop mode of competition influences both the suppression rate of E. repens biomass acquisition and the likelihood of shifts in E. repens biomass allocation. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Contribution of PsbS Function and Stomatal Conductance to Foliar Temperature in Higher Plants

PubMed Central

Kulasek, Milena; Bernacki, Maciej Jerzy; Ciszak, Kamil; Witoń, Damian; Karpiński, Stanisław

2016-01-01

Natural capacity has evolved in higher plants to absorb and harness excessive light energy. In basic models, the majority of absorbed photon energy is radiated back as fluorescence and heat. For years the proton sensor protein PsbS was considered to play a critical role in non-photochemical quenching (NPQ) of light absorbed by PSII antennae and in its dissipation as heat. However, the significance of PsbS in regulating heat emission from a whole leaf has never been verified before by direct measurement of foliar temperature under changing light intensity. To test its validity, we here investigated the foliar temperature changes on increasing and decreasing light intensity conditions (foliar temperature dynamics) using a high resolution thermal camera and a powerful adjustable light-emitting diode (LED) light source. First, we showed that light-dependent foliar temperature dynamics is correlated with Chl content in leaves of various plant species. Secondly, we compared the foliar temperature dynamics in Arabidopsis thaliana wild type, the PsbS null mutant npq4-1 and a PsbS-overexpressing transgenic line under different transpiration conditions with or without a photosynthesis inhibitor. We found no direct correlations between the NPQ level and the foliar temperature dynamics. Rather, differences in foliar temperature dynamics are primarily affected by stomatal aperture, and rapid foliar temperature increase during irradiation depends on the water status of the leaf. We conclude that PsbS is not directly involved in regulation of foliar temperature dynamics during excessive light energy episodes. PMID:27273581

Distortion in fingerprints: a statistical investigation using shape measurement tools.

PubMed

Sheets, H David; Torres, Anne; Langenburg, Glenn; Bush, Peter J; Bush, Mary A

2014-07-01

Friction ridge impression appearance can be affected due to the type of surface touched and pressure exerted during deposition. Understanding the magnitude of alterations, regions affected, and systematic/detectable changes occurring would provide useful information. Geometric morphometric techniques were used to statistically characterize these changes. One hundred and fourteen prints were obtained from a single volunteer and impressed with heavy, normal, and light pressure on computer paper, soft gloss paper, 10-print card stock, and retabs. Six hundred prints from 10 volunteers were rolled with heavy, normal, and light pressure on soft gloss paper and 10-print card stock. Results indicate that while different substrates/pressure levels produced small systematic changes in fingerprints, the changes were small in magnitude: roughly the width of one ridge. There were no detectable changes in the degree of random variability of prints associated with either pressure or substrate. In conclusion, the prints transferred reliably regardless of pressure or substrate. © 2014 American Academy of Forensic Sciences.

Light Quality Dependent Changes in Morphology, Antioxidant Capacity, and Volatile Production in Sweet Basil (Ocimum basilicum)

PubMed Central

Carvalho, Sofia D.; Schwieterman, Michael L.; Abrahan, Carolina E.; Colquhoun, Thomas A.; Folta, Kevin M.

2016-01-01

Narrow-bandwidth light treatments may be used to manipulate plant growth, development and metabolism. In this report LED-based light treatments were used to affect yield and metabolic content of sweet basil (Ocimum basilicum L. cv “Ceasar”) grown in controlled environments. This culinary herb produces an aroma highly appreciated by consumers, primarily composed of terpenes/terpenoids, phenylpropanoids, and fatty-acid- derived volatile molecules. Basil plants were grown under narrow-bandwidth light conditions, and leaf area, height, mass, antioxidant capacity and volatile emissions were measured at various time points. The results indicate reproducible significant differences in specific volatiles, and in biochemical classes of volatiles, compared to greenhouse grown plants. For example, basil plants grown under blue/red/yellow or blue/red/green wavelengths emit higher levels of a subset of monoterpenoid volatiles, while a blue/red/far-red treatment leads to higher levels of most sesquiterpenoid volatile molecules. Specific light treatments increase volatile content, mass, and antioxidant capacity. The results show that narrow-bandwidth illumination can induce discrete suites of volatile classes that affect sensory quality in commercial herbs, and may be a useful tool in improving commercial production. PMID:27635127

Light Quality Dependent Changes in Morphology, Antioxidant Capacity, and Volatile Production in Sweet Basil (Ocimum basilicum).

PubMed

Carvalho, Sofia D; Schwieterman, Michael L; Abrahan, Carolina E; Colquhoun, Thomas A; Folta, Kevin M

2016-01-01

Narrow-bandwidth light treatments may be used to manipulate plant growth, development and metabolism. In this report LED-based light treatments were used to affect yield and metabolic content of sweet basil (Ocimum basilicum L. cv "Ceasar") grown in controlled environments. This culinary herb produces an aroma highly appreciated by consumers, primarily composed of terpenes/terpenoids, phenylpropanoids, and fatty-acid- derived volatile molecules. Basil plants were grown under narrow-bandwidth light conditions, and leaf area, height, mass, antioxidant capacity and volatile emissions were measured at various time points. The results indicate reproducible significant differences in specific volatiles, and in biochemical classes of volatiles, compared to greenhouse grown plants. For example, basil plants grown under blue/red/yellow or blue/red/green wavelengths emit higher levels of a subset of monoterpenoid volatiles, while a blue/red/far-red treatment leads to higher levels of most sesquiterpenoid volatile molecules. Specific light treatments increase volatile content, mass, and antioxidant capacity. The results show that narrow-bandwidth illumination can induce discrete suites of volatile classes that affect sensory quality in commercial herbs, and may be a useful tool in improving commercial production.

A step forward in the study of the electroerosion by optical methods

NASA Astrophysics Data System (ADS)

Aparicio, R.; Gale, M. F. Ruiz; Hogert, E. N.; Landau, M. R.; Gaggioli, y. N. G.

2003-05-01

This work develops two theoretical models of surfaces to explain the behavior of the light scattered by samples that suffers some alteration. In a first model, it is evaluated the mean intensity scattered by the sample, analyzing the different curves obtained as function of the eroded/total surface ratio. The theoretical results are compared with those obtained experimentally. It can be seen that there exists a strong relation between the electroerosion level and the light scattered by the sample. A second model analyzes a surface with random changes in its roughness. A translucent surface with its roughness changing in a controlled way is studied. Then, the correlation coefficient variation as function of the roughness variation is determined by the transmission speckle correlation method. The obtained experimental values are compared with those obtained with this model. In summary, it can be shown that the first- and second-order statistics properties of the transmitted or reflected light by a sample with a variable topography can be taken account as a parameter to analyze these morphologic changes.

Assessment of Environmental Impacts of Light-Duty Vehicle Dieselization

DOT National Transportation Integrated Search

1980-06-01

This report provides a first-level assessment of the environmental effects which might result if diesel vehicles in large numbers were produced and sold, thereby changing the mix of vehicles in the in-use fleet so that a substantial fraction were die...

Light differentially regulates cell division and the mRNA abundance of pea nucleolin during de-etiolation

NASA Technical Reports Server (NTRS)

Reichler, S. A.; Balk, J.; Brown, M. E.; Woodruff, K.; Clark, G. B.; Roux, S. J.

2001-01-01

The abundance of plant nucleolin mRNA is regulated during de-etiolation by phytochrome. A close correlation between the mRNA abundance of nucleolin and mitosis has also been previously reported. These results raised the question of whether the effects of light on nucleolin mRNA expression were a consequence of light effects on mitosis. To test this we compared the kinetics of light-mediated increases in cell proliferation with that of light-mediated changes in the abundance of nucleolin mRNA using plumules of dark-grown pea (Pisum sativum) seedlings. These experiments show that S-phase increases 9 h after a red light pulse, followed by M-phase increases in the plumule leaves at 12 h post-irradiation, a time course consistent with separately measured kinetics of red light-induced increases in the expression of cell cycle-regulated genes. These increases in cell cycle-regulated genes are photoreversible, implying that the light-induced increases in cell proliferation are, like nucleolin mRNA expression, regulated via phytochrome. Red light stimulates increases in the mRNA for nucleolin at 6 h post-irradiation, prior to any cell proliferation changes and concurrent with the reported timing of phytochrome-mediated increases of rRNA abundance. After a green light pulse, nucleolin mRNA levels increase without increasing S-phase or M-phase. Studies in animals and yeast indicate that nucleolin plays a significant role in ribosome biosynthesis. Consistent with this function, pea nucleolin can rescue nucleolin deletion mutants of yeast that are defective in rRNA synthesis. Our data show that during de-etiolation, the increased expression of nucleolin mRNA is more directly regulated by light than by mitosis.

New device for monitoring the colors of the night

NASA Astrophysics Data System (ADS)

Spoelstra, Henk

2014-05-01

The introduction of LED lighting in the outdoor environment may increase the amount of blue light in the night sky color spectrum. This can cause more light pollution due to Rayleigh scattering of the shorter wavelengths. Blue light may also have an impact on circadian rhythm of humans due to the suppression of melatonin. At present no long-term data sets of the color spectrum of the night sky are available. In order to facilitate the monitoring of levels and variations in the night sky spectrum, a low cost multi-filter instrument has been developed. Design considerations are described as well as the choice of suitable filters, which are critical - especially in the green wavelength band from 500 to 600 nm. Filters from the optical industry were chosen for this band because available astronomical filters exclude some or all of the low and high-pressure sodium lines from lamps, which are important in light pollution research. Correction factors are calculated to correct for the detector response and filter transmissions. Results at a suburban monitoring station showed that the light levels between 500 and 600 nm are dominant during clear and cloudy skies. The relative contribution of blue light increases with a clear moonless night sky. The change in color spectrum of the night sky under moonlit skies is more complex and is still under study.

DRIVE CYCLE EFFICIENCY AND EMISSIONS ESTIMATES FOR REACTIVITY CONTROLLED COMPRESSION IGNITION IN A MULTI-CYLINDER LIGHT-DUTY DIESEL ENGINE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Curran, Scott; Briggs, Thomas E; Cho, Kukwon

2011-01-01

In-cylinder blending of gasoline and diesel to achieve Reactivity Controlled Compression Ignition (RCCI) has been shown to reduce NOx and PM emissions while maintaining or improving brake thermal efficiency as compared to conventional diesel combustion (CDC). The RCCI concept has an advantage over many advanced combustion strategies in that by varying both the percent of premixed gasoline and EGR rate, stable combustion can be extended over more of the light-duty drive cycle load range. Changing the percent premixed gasoline changes the fuel reactivity stratification in the cylinder providing further control of combustion phasing and pressure rise rate than the usemore » of EGR alone. This paper examines the combustion and emissions performance of light-duty diesel engine using direct injected diesel fuel and port injected gasoline to carry out RCCI for steady-state engine conditions which are consistent with a light-duty drive cycle. A GM 1.9L four-cylinder engine with the stock compression ratio of 17.5:1, common rail diesel injection system, high-pressure EGR system and variable geometry turbocharger was modified to allow for port fuel injection with gasoline. Engine-out emissions, engine performance and combustion behavior for RCCI operation is compared against both CDC and a premixed charge compression ignition (PCCI) strategy which relies on high levels of EGR dilution. The effect of percent of premixed gasoline, EGR rate, boost level, intake mixture temperature, combustion phasing and pressure rise rate is investigated for RCCI combustion for the light-duty modal points. Engine-out emissions of NOx and PM were found to be considerably lower for RCCI operation as compared to CDC and PCCI, while HC and CO emissions were higher. Brake thermal efficiency was similar or higher for many of the modal conditions for RCCI operation. The emissions results are used to estimate hot-start FTP-75 emissions levels with RCCI and are compared against CDC and PCCI modes.« less

The Effects of Dietary Carotenoid Supplementation and Retinal Carotenoid Accumulation on Vision-Mediated Foraging in the House Finch

PubMed Central

Toomey, Matthew B.; McGraw, Kevin J.

2011-01-01

Background For many bird species, vision is the primary sensory modality used to locate and assess food items. The health and spectral sensitivities of the avian visual system are influenced by diet-derived carotenoid pigments that accumulate in the retina. Among wild House Finches (Carpodacus mexicanus), we have found that retinal carotenoid accumulation varies significantly among individuals and is related to dietary carotenoid intake. If diet-induced changes in retinal carotenoid accumulation alter spectral sensitivity, then they have the potential to affect visually mediated foraging performance. Methodology/Principal Findings In two experiments, we measured foraging performance of house finches with dietarily manipulated retinal carotenoid levels. We tested each bird's ability to extract visually contrasting food items from a matrix of inedible distracters under high-contrast (full) and dimmer low-contrast (red-filtered) lighting conditions. In experiment one, zeaxanthin-supplemented birds had significantly increased retinal carotenoid levels, but declined in foraging performance in the high-contrast condition relative to astaxanthin-supplemented birds that showed no change in retinal carotenoid accumulation. In experiments one and two combined, we found that retinal carotenoid concentrations predicted relative foraging performance in the low- vs. high-contrast light conditions in a curvilinear pattern. Performance was positively correlated with retinal carotenoid accumulation among birds with low to medium levels of accumulation (∼0.5–1.5 µg/retina), but declined among birds with very high levels (>2.0 µg/retina). Conclusion/Significance Our results suggest that carotenoid-mediated spectral filtering enhances color discrimination, but that this improvement is traded off against a reduction in sensitivity that can compromise visual discrimination. Thus, retinal carotenoid levels may be optimized to meet the visual demands of specific behavioral tasks and light environments. PMID:21747917

Regulation of carotenoid accumulation and the expression of carotenoid metabolic genes in citrus juice sacs in vitro.

PubMed

Zhang, Lancui; Ma, Gang; Kato, Masaya; Yamawaki, Kazuki; Takagi, Toshihiko; Kiriiwa, Yoshikazu; Ikoma, Yoshinori; Matsumoto, Hikaru; Yoshioka, Terutaka; Nesumi, Hirohisa

2012-01-01

In the present study, to investigate the mechanisms regulating carotenoid accumulation in citrus, a culture system was set up in vitro with juice sacs of three citrus varieties, Satsuma mandarin (Citrus unshiu Marc.), Valencia orange (Citrus sinensis Osbeck), and Lisbon lemon (Citrus limon Burm.f.). The juice sacs of all the three varieties enlarged gradually with carotenoid accumulation. The changing patterns of carotenoid content and the expression of carotenoid metabolic genes in juice sacs in vitro were similar to those ripening on trees in the three varieties. Using this system, the changes in the carotenoid content and the expression of carotenoid metabolic genes in response to environmental stimuli were investigated. The results showed that carotenoid accumulation was induced by blue light treatment, but was not affected by red light treatment in the three varieties. Different regulation of CitPSY expression, which was up-regulated by blue light while unaffected by red light, led to different changes in carotenoid content in response to these two treatments in Satsuma mandarin and Valencia orange. In all three varieties, increases in carotenoid content were observed with sucrose and mannitol treatments. However, the accumulation of carotenoid in the two treatments was regulated by distinct mechanisms at the transcriptional level. With abscisic acid (ABA) treatment, the expression of the genes investigated in this study was up-regulated in Satsuma mandarin and Lisbon lemon, indicating that ABA induced its own biosynthesis at the transcriptional level. This feedback regulation of ABA led to decreases in carotenoid content. With gibberellin (GA) treatment, carotenoid content was significantly decreased in the three varieties. Changes in the expression of genes related to carotenoid metabolism varied among the three varieties in response to GA treatment. These results provided insights into improving carotenoid content and composition in citrus during fruit maturation.

Regulation of carotenoid accumulation and the expression of carotenoid metabolic genes in citrus juice sacs in vitro

PubMed Central

Zhang, Lancui; Ma, Gang; Kato, Masaya; Yamawaki, Kazuki; Takagi, Toshihiko; Kiriiwa, Yoshikazu; Ikoma, Yoshinori; Matsumoto, Hikaru; Yoshioka, Terutaka; Nesumi, Hirohisa

2012-01-01

In the present study, to investigate the mechanisms regulating carotenoid accumulation in citrus, a culture system was set up in vitro with juice sacs of three citrus varieties, Satsuma mandarin (Citrus unshiu Marc.), Valencia orange (Citrus sinensis Osbeck), and Lisbon lemon (Citrus limon Burm.f.). The juice sacs of all the three varieties enlarged gradually with carotenoid accumulation. The changing patterns of carotenoid content and the expression of carotenoid metabolic genes in juice sacs in vitro were similar to those ripening on trees in the three varieties. Using this system, the changes in the carotenoid content and the expression of carotenoid metabolic genes in response to environmental stimuli were investigated. The results showed that carotenoid accumulation was induced by blue light treatment, but was not affected by red light treatment in the three varieties. Different regulation of CitPSY expression, which was up-regulated by blue light while unaffected by red light, led to different changes in carotenoid content in response to these two treatments in Satsuma mandarin and Valencia orange. In all three varieties, increases in carotenoid content were observed with sucrose and mannitol treatments. However, the accumulation of carotenoid in the two treatments was regulated by distinct mechanisms at the transcriptional level. With abscisic acid (ABA) treatment, the expression of the genes investigated in this study was up-regulated in Satsuma mandarin and Lisbon lemon, indicating that ABA induced its own biosynthesis at the transcriptional level. This feedback regulation of ABA led to decreases in carotenoid content. With gibberellin (GA) treatment, carotenoid content was significantly decreased in the three varieties. Changes in the expression of genes related to carotenoid metabolism varied among the three varieties in response to GA treatment. These results provided insights into improving carotenoid content and composition in citrus during fruit maturation. PMID:21994171

Design, fabrication, and analysis of miniature reflective oxygen monitoring system for use in PDT of esophageal carcinoma

NASA Astrophysics Data System (ADS)

Premasiri, Amaranath; Happawana, Gemunu

2008-02-01

Photodynamic therapy (PDT) is an effective and minimally invasive treatment modality with relatively less side effects, which is approved by FDA for the treatment of esophageal cancer. Maximum therapeutic outcome of the PDT protocol for each individual patient requires optimization of the components of PDT operating at their highest efficacy. Tumor necrosis, the method of malignant tissue destruction by PDT, is carried out by the toxic singlet oxygen molecules that are being formed from the molecular oxygen in the tumor. The availability of molecular oxygen, hence being the rate limiting step for PDT plays a key role in the treatment protocol. Currently the PDT of esophageal carcinoma is rather a blind process since there is no method to monitor the tumor oxygen level during the treatment. In this paper we present an optical technique to monitor molecular oxygen level in the PDT milieu. The technique described herein is a reflection oximetry technique designed with small semiconductor lasers and a silicon photodiode. The light used for monitoring system comes from two semiconductor diode lasers of 650 nm and 940 nm wavelengths. The two lasers and the photodiode are mounted onto a small package which is to be imprinted onto a balloon catheter containing the PDT light delivery system. Lasers and the photodiode are powered and controlled by a control box that is connected via a cable. Light sources and the respective photodiode output are controlled by the LabVIEW virtual instrumentation. The sequential on and off light source and the respective reflective signal are processed with MATLAB. The latter code integrates with LabVIEW to make an automatic calculation of the corresponding light absorption by each chromophore and to calculate the change in oxygen level as well as the amount of blood and oxygen present in the treatment area. The designed system is capable of monitoring the change in oxygen level and the blood flow in any part of the human body where the package is possible to place.

Differential sorting of the vesicular glutamate transporter 1 into a defined vesicular pool is regulated by light signaling involving the clock gene Period2.

PubMed

Yelamanchili, Sowmya V; Pendyala, Gurudutt; Brunk, Irene; Darna, Mahesh; Albrecht, Urs; Ahnert-Hilger, Gudrun

2006-06-09

Synaptic strength depends on the amount of neurotransmitter stored in synaptic vesicles. The vesicular transmitter content has recently been shown to be directly dependent on the expression levels of vesicular neurotransmitter transporters indicating that the transport capacity of synaptic vesicles is a critical determinant for synaptic efficacy. Using synaptic vesicles prepared from whole brain at different times of the day we now show that the amount of vesicular glutamate transporter (VGLUT) 1 undergoes strong diurnal cycling. VGLUT1 protein levels are high before the start of the light period, decline at noon, increase again before start of the dark period, and decline again at midnight. Mice kept in complete darkness showed within a 24-h period only a single peak of VGLUT1 expression in the middle of the rest phase. In contrast, mice lacking the period gene Period 2, a core component of the circadian clock, did not show any light-cycle-dependent changes of VGLUT1 levels. No other of several synaptic vesicle proteins examined underwent circadian cycling. Circadian cycling of VGLUT1 was not seen when analyzing homogenate or synaptosomes, the starting fraction for vesicle preparation. Circadian cycling of VGLUT1 was also not reflected at the mRNA level. We conclude that nerve terminals are endowed with mechanisms that regulate quantal size by changing the copy number of transporters in synaptic vesicles. A reduced amount of VGLUT1 per vesicle is probably achieved by means of selective sorting controlled by clock genes.

The crustacean eye: dark/light adaptation, polarization sensitivity, flicker fusion frequency, and photoreceptor damage.

PubMed

Meyer-Rochow, V B

2001-12-01

Compound eyes, nauplius eyes, frontal organs, intracerebral ocelli, and caudal photoreceptors are the main light and darkness detectors in crustaceans, but they need not be present all at once in an individual and in some crustaceans no photoreceptors whatsoever are known. Compound eye designs reflect on their functions and have evolved to allow the eye to operate optimally under a variety of environmental conditions. Dark-light-adaptational changes manifest themselves in pigment granule translocations, cell movements, and optical adjustments which fine-tune an eye's performance to rapid and unpredictable fluctuations in ambient light intensities as well as to the slower and predictable light level changes associated with day and night oscillations. Recycling of photoreceptive membrane and light-induced membrane collapse are superficially similar events that involve the transduction cascade, intracellular calcium, and membrane fatty acid composition, but which differ in aetiology and longterm consequence. Responses to intermittant illumination and linearly polarized light evoke in the eye of many crustaceans characteristic responses that appear to be attuned to each species' special needs. How the visual responses are processed more centrally and to what extent a crustacean makes behavioural use of e-vector discrimination and flickering lights are questions, however, that still have not been satisfactorily answered for the vast majority of all crustacean species. The degree of light-induced photoreceptor damage depends on a large number of variables, but once manifest, it tends to be progressive and irreversible. Concomittant temperature stress aggravates the situation and there is evidence that free radicals and lipid hydroperoxides are involved.

Influence of skin type and wavelength on light wave reflectance.

PubMed

Fallow, Bennett A; Tarumi, Takashi; Tanaka, Hirofumi

2013-06-01

A new application of photoplethysmography (PPG) has emerged recently to provide the possibility of heart rate monitoring without a telemetric chest strap. The aim of this study was to determine if a new device could detect pulsation over a broad range of skin types, and what light wavelength would be most suitable for detecting the signals. A light emitting diode-based PPG system was used to detect changes in pulsatile blood flow on 23 apparently healthy individuals (11 male and 12 female, 20-59 years old) of varying skin types classified according to a questionnaire in combination with digital photographs with a skin type chart. Four different light wavelengths (470, 520, 630, and 880 nm) were tested. Normalized modulation level is calculated as the AC/DC component ratio and represents the change in flow over the underlying constant state of flow or perfusion. In the resting condition, green light wavelength (520 nm) displayed greater modulation (p < 0.001) than all the other wavelengths analyzed regardless of skin types. Type V (dark brown) skin type was significantly lower in modulation than all other skin types. In the exercise condition, both blue (470 nm) and green (520 nm) light wavelengths displayed greater signal-to-noise ratios than red (630 nm) or infrared (880 nm) light wavelengths (p < 0.001). We concluded that a PPG-based device can detect pulsation across all skin types and that a greater resolution was obtained using a green light wavelength at rest and a green or blue light wavelength during exercise.

Changes in the quality of medicines during storage under LED lighting and consideration of countermeasures.

PubMed

Yamashita, Shuuji; Iguchi, Kazuhiro; Noguchi, Yoshihiro; Sakai, Chihiro; Yokoyama, Satoshi; Ino, Yoko; Hayashi, Hideki; Teramachi, Hitomi; Sako, Magoichi; Sugiyama, Tadashi

2018-01-01

In recent years, the popularity of LED lighting has rapidly increased, owing to its many advantages, including economic benefits. We examined the change in the quality of drugs during storage under LED and fluorescent lighting and found that some medicines exhibited a different degree of color change depending on the light source. The purpose of this study was to investigate the effects of different plastic storage bags on the color change over time when various medicines were stored under LED and fluorescent lighting conditions. Photostability tests were conducted on several types of target drugs. Subsequently, subjective evaluation by ten evaluators and objective evaluation by image analysis software were carried out regarding color change. A similar change in color tone was observed after all types of illumination. Subjective evaluation by 10 evaluators revealed that "change in color tone" occurred in the order of bulb-color LED lighting < daylight-color LED lighting < fluorescent lighting, regardless of the type of plastic bags. A similar tendency was observed also in objective evaluation. In this study, it was considered that a brown light-shielding plastic bag was more effective than a normal plastic bag for the prevention of the color change of medicines stored under LED lighting. The above results suggested that the most appropriate combination of plastic bag and light source for medicine storage was a brown light-shielding plastic bag and bulb-color LED lighting.

Control of the Diurnal Pattern of Methane Emission from Emergent Aquatic Macrophytes by Gas Transport Mechanisms

NASA Technical Reports Server (NTRS)

Whiting, Gary J.; Chanton, Jeffrey P.

1995-01-01

Methane emissions from Typha latifolia (L.) showed a large mid-morning transient peak associated with rising light levels. This peak was also associated with a steep decline in lacunal CH, concentrations near the stem base. This pattern contrasted sharply with emissions from Peltandra virginica (L.) that gradually rose to a peak in the mid-afternoon corresponding to elevated air temperatures. Internal CH4 concentrations within P. virginica stems did not change significantly over the diurnal period. Stomatal conductance appeared to correlate directly with light levels in both plant types and were not associated with peak CH4 emission events in either plant. These patterns are consistent with a convective throughflow and diffusive gas ventilation systems for Typha and Peltandra, respectively. Further effects of the convective throughflow in T. latifolia were evident in the elevated CH4 concentrations measured within brown leaves as contrasted to the near ambient levels measured within live green leaves. Experimental manipulation of elevated and reduced CO2 levels in the atmosphere surrounding the plants and of light/dark periods suggested that stomatal aperture has little or no control of methane emissions from T. latifolia.

An investigation of the role of defect levels on the radiation response of synthetic diamond crystals when used as sensors for the detection of mammography X-rays.

PubMed

Ade, Nicholas

2017-09-01

This study evaluates the role of defects on the performances of synthetic diamond sensors on exposure to mammography X-rays. Through systematic investigations, the main cause of instability of response of examined sensors necessitating pre-irradiation was isolated and ascribed to the presence of ambient light which has the effect of emptying shallow trapping levels. The changes in response between measurements in light and dark conditions varied from 2.8 ± 1.2% to 63.0 ± 0.3%. Sensitivities between 0.4 and 6.7nCGy -1 mm -3 determined for the sensors varied with defect levels. The study indicates that differences in crystal quality due to the presence and influence of defects would cause a discrepancy in the dosimetric performances of various diamond detectors. Once a sensor plate is selected (based on the influence of defect levels) and coupled to the probe housing with the response of the diamond sensor stabilised and appropriately shielded from ambient light, daily priming is not needed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Light-induced dynamic structural color by intracellular 3D photonic crystals in brown algae

PubMed Central

2018-01-01

Natural photonic crystals are responsible for strong reflectance at selective wavelengths in different natural systems. We demonstrate that intracellular opal-like photonic crystals formed from lipids within photosynthetic cells produce vivid structural color in the alga Cystoseira tamariscifolia. The reflectance of the opaline vesicles is dynamically responsive to environmental illumination. The structural color is present in low light–adapted samples, whereas higher light levels produce a slow disappearance of the structural color such that it eventually vanishes completely. Once returned to low-light conditions, the color re-emerges. Our results suggest that these complex intracellular natural photonic crystals are responsive to environmental conditions, changing their packing structure reversibly, and have the potential to manipulate light for roles beyond visual signaling. PMID:29651457

Microgravity does not alter plant stand gas exchange of wheat at moderate light levels and saturating CO2 concentration.

PubMed

Monje, O; Stutte, G; Chapman, D

2005-10-01

Plant stand gas exchange was measured nondestructively in microgravity during the Photosynthesis Experiment Subsystem Testing and Operations experiment conducted onboard the International Space Station. Rates of evapotranspiration and photosynthesis measured in space were compared with ground controls to determine if microgravity directly affects whole-stand gas exchange of Triticum aestivum. During six 21-day experiment cycles, evapotranspiration was determined continuously from water addition rates to the nutrient delivery system, and photosynthesis was determined from the amount of CO2 added to maintain the chamber CO2 concentration setpoint. Plant stand evapotranspiration, net photosynthesis, and water use efficiency were not altered by microgravity. Although leaf area was significantly reduced in microgravity-grown plants compared to ground control plants, leaf area distribution was not affected enough to cause significant differences in the amounts of light absorbed by the flight and ground control plant stands. Microgravity also did not affect the response of evapotranspiration to changes in chamber vapor pressure difference of 12-day-old wheat plant stands. These results suggest that gravity naïve plants grown at moderate light levels (300 micromol m(-2) s(-1)) behave the same as ground control plants. This implies that future plant-based regenerative life support systems can be sized using 1 g data because water purification and food production rates operate at nearly the same rates as in 1 g at moderate light levels. However, it remains to be verified whether the present results are reproducible in plants grown under stronger light levels.

Transcriptional analysis of Volvox photoreceptors suggests the existence of different cell-type specific light-signaling pathways.

PubMed

Kianianmomeni, Arash; Hallmann, Armin

2015-02-01

Photosynthetic organisms, e.g., plants including green algae, use a sophisticated light-sensing system, composed of primary photoreceptors and additional downstream signaling components, to monitor changes in the ambient light environment towards adjust their growth and development. Although a variety of cellular processes, e.g., initiation of cleavage division and final cellular differentiation, have been shown to be light-regulated in the green alga Volvox carteri, little is known about the underlying light perception and signaling pathways. This multicellular alga possesses at least 12 photoreceptors, i.e., one phototropin (VcPhot), four cryptochromes (VcCRYa, VcCRYp, VcCRYd1, and VcCRYd2), and seven members of rhodopsin-like photoreceptors (VR1, VChR1, VChR2, VcHKR1, VcHKR2, VcHKR3, and VcHKR4), which display distinct light-dependent chemical processes based on their protein architectures and associated chromophores. Gene expression analyses could show that the transcript levels of some of the photoreceptor genes (e.g., VChR1 and VcHKR1) accumulate during division cleavages, while others (e.g., VcCRYa, VcCRYp, and VcPhot) accumulate during final cellular differentiation. However, the pattern of transcript accumulation changes when the alga switches to the sexual development. Eight photoreceptor genes, e.g., VcPhot, VcCRYp, and VcHKR1, are highly expressed in the somatic cells, while only the animal-type rhodopsin VR1 was found to be highly expressed in the reproductive cells/embryos during both asexual and sexual life cycles. Moreover, accumulation of VChR1 and VcCRYa transcripts is more sensitive to light and changes in response to more than one light quality. Obviously, different regulatory mechanisms underlying gene expression control transcript accumulation of photoreceptors not only during development, but also in a cell-type specific way and in response to various external signals such as light quality. The transcriptional patterns described in this study show that Volvox photoreceptors are mostly expressed in a cell-type specific manner. This gives reason to believe that cell-type specific light-signaling pathways allow differential regulation of cellular and developmental processes in response to the environmental light cues.

Research | Energy Systems Integration Facility | NREL

Science.gov Websites

levels of variable supply and demand? How do we keep the lights on and the fuel flowing in a world of , regulatory frameworks, and value propositions for consumers in this changing world? NREL's crosscutting Partner with our world-class researchers Work

Proteomics analysis reveals a dynamic diurnal pattern of photosynthesis-related pathways in maize leaves.

PubMed

Feng, Dan; Wang, Yanwei; Lu, Tiegang; Zhang, Zhiguo; Han, Xiao

2017-01-01

Plant leaves exhibit differentiated patterns of photosynthesis rates under diurnal light regulation. Maize leaves show a single-peak pattern without photoinhibition at midday when the light intensity is maximized. This mechanism contributes to highly efficient photosynthesis in maize leaves. To understand the molecular basis of this process, an isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomics analysis was performed to reveal the dynamic pattern of proteins related to photosynthetic reactions. Steady, single-peak and double-peak protein expression patterns were discovered in maize leaves, and antenna proteins in these leaves displayed a steady pattern. In contrast, the photosystem, carbon fixation and citrate pathways were highly controlled by diurnal light intensity. Most enzymes in the limiting steps of these pathways were major sites of regulation. Thus, maize leaves optimize photosynthesis and carbon fixation outside of light harvesting to adapt to the changes in diurnal light intensity at the protein level.

Antioxidant effects of Lycium barbarum polysaccharides on photoreceptor degeneration in the light-exposed mouse retina.

PubMed

Tang, Liujiu; Bao, Shuyin; Du, Yu; Jiang, Zengyan; Wuliji, A O; Ren, Xiang; Zhang, Chenghong; Chu, Haiying; Kong, Li; Ma, Haiying

2018-04-20

We assessed the neuroprotective effects of Lycium barbarum Polysaccharides (LBP) on photoreceptor degeneration and the mechanisms involved in oxidative stress in light-exposed mouse retinas. Mice were given a gavage of LBP (150 mg/kg or 300 mg/kg) or phosphate buffered saline (PBS) for 7 days before exposure to light (5000 lx for 24 h). We found that LBP significantly improved the electroretinography (ERG) amplitudes of the a- and b-waves that had been attenuated by light exposure. In addition, changes caused by light exposure including photoreceptor cell loss, nuclear condensation, an increased number of mitochondria vacuoles, outer membrane disc swelling and cristae fractures were distinctly ameliorated by LBP. LBP treatment also significantly prevented the generation of reactive oxygen species (ROS) compared with PBS treatment. The levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and thioredoxin reductase (TrxR1) mRNA were decreased in PBS-treated mice compared with controls but increased remarkably in LBP-treated mice. The mRNA levels of the DNA repair gene Poly (ADP-ribose) polymerase (PARP14) was increased in PBS-treated mice but decreased significantly in the LBP-treated mice. Our findings indicate that pretreatment with LBP effectively protected photoreceptor cells against light-induced retinal damage probably through the up-regulation of the antioxidative genes Nrf2 and TrxR1, the elimination of oxygen free radicals, and the subsequent reduction in the mitochondrial reaction to oxidative stress and enhancement in antioxidant capacity. In addition, the decreased level of PARP14 mRNA in LBP-treated mice also indicated a protective effect of LBP on delaying photoreceptor in the light-damaged retina. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Ultraviolet-B radiation increases serum 25-hydroxyvitamin D levels: the effect of UVB dose and skin color.

PubMed

Armas, Laura A G; Dowell, Susan; Akhter, Mohammed; Duthuluru, Sowjanya; Huerter, Christopher; Hollis, Bruce W; Lund, Richard; Heaney, Robert P

2007-10-01

Ultraviolet (UV)-B light increases vitamin D levels, but the dose response and the effect of skin pigmentation have not been well characterized. We sought to define the relationship between UVB exposure and 25-hydroxyvitamin D (25-OH-D) concentrations as a function of skin pigmentation. Seventy two participants with various skin tones had 90% of their skin exposed to UVB light (20-80 mJ/cm2) 3 times a week for 4 weeks. Serum 25-OH-D was measured weekly. Eighty percent of the variation in treatment response was explained by UVB dose and skin tone. Therapeutically important changes in 25-OH-D were achieved with minimal tanning. Four weeks was not long enough to reach a steady state at the higher dose rates. The response of 25-OH-D levels to UVB light is dependent on skin pigmentation and the amount of UVB given, and useful increases in vitamin D status can be achieved by defined UVB doses small enough to produce only minimal tanning.

[Metabolism of carbohydrates in the cells of green sulphur bacteria Chlorobium limicola Ya-2002].

PubMed

Horishnyĭ, M B; Hudz', S P; Hnatush, S O

2009-01-01

The nature of carbohydrates that accumulate in the cells of photosynthetic green sulphur bacteria of Chlorobium limicola Ya-2002 has been investigated. It is shown by infra-red spectrometry, that carbohydrates accumulated in the cells of bacteria are identical (by 90-95%) to glycogen of the bull liver. Exogenous glucose, saccharose, maltose, did not stimulate formation of glycogen. Growth of glycogen level in the cells of bacteria was observed at addition of acetate or piruvate in the conditions of bacteria cultivation in the light and in the presence CO2 and H2S in the environment. Washed cells of C. limicola Ya-2002 did not use glucose of the environment neither in the conditions of illumination nor in darkness, however acetate and piruvate are actively used in the light. During incubation of the washed cells in darkness the level of glycogen fell down approximately three times. Its amount during cells incubation in the light did not change. The decline of glycogen level in cells during their incubation in darkness was accompanied by piling up of carbonic acids in the environment acetate prevailing among them.

Low-level Light Therapy for Treatment of Diabetic Foot Ulcer: A Review of Clinical Experiences.

PubMed

Tchanque-Fossuo, Catherine N; Ho, Derek; Dahle, Sara E; Koo, Eugene; Isseroff, R Rivkah; Jagdeo, Jared

2016-07-01

Diabetic foot ulcers (DFU) represent a significant complication of diabetes mellitus (DM). DFU affect one in four patients with DM and treatments of DFU are limited and challenging. The management of DFU remains a significant healthcare and socioeconomic burden ($245 billion). There is a wide range of advanced therapies for DFU, but these are costly and have demonstrated only minimal efficacy in limited published studies. An emerging treatment modality to improve DFU and optimize wound healing is the use of low-level light therapy (LLLT). LLLT involves the use of light in the form of low-level or low-power laser or light emitting diodes to alter biochemical pathways, which may result in changes to cell shape, cell migration, and cell signaling.
To review published clinical experiences (case series and case reports) using LLLT for treatment of DFU, and provide evidence-based recommendations and future directions on the potential of LLLT as a therapeutic modality for DFU.
On January 16, 2016 we searched the published literature using databases: PubMed, EMBASE, CINAHL, and Web of Science with key terms: "diabetic foot" AND ("low level laser therapy" OR "low level light therapy" OR "LLLT" OR "light emitting diode" OR "phototherapy" OR "laser").
After screening of titles, abstracts and/or full-text, 7 original articles were suitable in our review. Our review contains 5 case series and 2 case reports that evaluated LLLT for treatment of DFU, and all reviewed studies have shown positive improvement of DFU using LLLT with no adverse events, albeit with limitations that may be minimized with future RCTs.
LLLT is an emerging and promising treatment modality to current alternatives that are costly and have shown limited success. Based upon the published evidence, we envision additional research may allow for stronger recommendation with LLLT for treatment of DFU.

J Drugs Dermatol. 2016;15(7):843-848.

Rhythmic brain stimulation reduces anxiety-related behavior in a mouse model based on meditation training.

PubMed

Weible, Aldis P; Piscopo, Denise M; Rothbart, Mary K; Posner, Michael I; Niell, Cristopher M

2017-03-07

Meditation training induces changes at both the behavioral and neural levels. A month of meditation training can reduce self-reported anxiety and other dimensions of negative affect. It also can change white matter as measured by diffusion tensor imaging and increase resting-state midline frontal theta activity. The current study tests the hypothesis that imposing rhythms in the mouse anterior cingulate cortex (ACC), by using optogenetics to induce oscillations in activity, can produce behavioral changes. Mice were randomly assigned to groups and were given twenty 30-min sessions of light pulses delivered at 1, 8, or 40 Hz over 4 wk or were assigned to a no-laser control condition. Before and after the month all mice were administered a battery of behavioral tests. In the light/dark box, mice receiving cortical stimulation had more light-side entries, spent more time in the light, and made more vertical rears than mice receiving rhythmic cortical suppression or no manipulation. These effects on light/dark box exploratory behaviors are associated with reduced anxiety and were most pronounced following stimulation at 1 and 8 Hz. No effects were seen related to basic motor behavior or exploration during tests of novel object and location recognition. These data support a relationship between lower-frequency oscillations in the mouse ACC and the expression of anxiety-related behaviors, potentially analogous to effects seen with human practitioners of some forms of meditation.

Influence of drug-light-interval on photodynamic therapy of port wine stains--simulation and validation of mathematic models.

PubMed

Huang, Naiyan; Cheng, Gang; Li, Xiaosong; Gu, Ying; Liu, Fanguang; Zhong, Qiuhai; Wang, Ying; Zen, Jin; Qiu, Haixia; Chen, Hongxia

2008-06-01

We established mathematical models of photodynamic therapy (PDT) on port wine stains (PWS) to observe the effect of drug-light-interval (DLI) and optimize light dose. The mathematical simulations included determining (1) the distribution of laser light by Monte Carlo model, (2) the change of photosensitizer concentration in PWS vessels by a pharmacokinetics equation, (3) the change of photosensitizer distribution in tissue outside the vessels by a diffuse equation and photobleaching equation, and (4) the change of tissue oxygen concentration by the Fick's law with a consideration of the oxygen consumption during PDT. The concentration of singlet oxygen in the tissue model was calculated by the finite difference method. To validate those models, a PWS lesion of the same patient was divided into two areas and subjected to different DLIs and treated with different energy density. The color of lesion was assessed 8-12 weeks later. The simulation indicated the singlet oxygen concentration of the second treatment area (DLI=40 min) was lower than that of the first treatment area (DLI=0 min). However, it would be increased to a level similar to that of the first treatment area if the light irradiation time of the second treatment area was prolonged from 40 min to 55 min. Clinical results were consistent with the results predicted by the mathematical models. The mathematical models established in this study are helpful to optimize clinical protocol.

Coastal urban lighting has ecological consequences for multiple trophic levels under the sea.

PubMed

Bolton, D; Mayer-Pinto, M; Clark, G F; Dafforn, K A; Brassil, W A; Becker, A; Johnston, E L

2017-01-15

Urban land and seascapes are increasingly exposed to artificial lighting at night (ALAN), which is a significant source of light pollution. A broad range of ecological effects are associated with ALAN, but the changes to ecological processes remain largely unstudied. Predation is a key ecological process that structures assemblages and responds to natural cycles of light and dark. We investigated the effect of ALAN on fish predatory behaviour, and sessile invertebrate prey assemblages. Over 21days fish and sessile assemblages were exposed to 3 light treatments (Day, Night and ALAN). An array of LED spotlights was installed under a wharf to create the ALAN treatments. We used GoPro cameras to film during the day and ALAN treatments, and a Dual frequency IDentification SONar (DIDSON) to film during the night treatments. Fish were most abundant during unlit nights, but were also relatively sedentary. Predatory behaviour was greatest during the day and under ALAN than at night, suggesting that fish are using structures for non-feeding purposes (e.g. shelter) at night, but artificial light dramatically increases their predatory behaviour. Altered predator behaviour corresponded with structural changes to sessile prey assemblages among the experimental lighting treatments. We demonstrate the direct effects of artificial lighting on fish behaviour and the concomitant indirect effects on sessile assemblage structure. Current and future projected use of artificial lights has the potential to significantly affect predator-prey interactions in marine systems by altering habitat use for both predators and prey. However, developments in lighting technology are a promising avenue for mitigation. This is among the first empirical evidence from the marine system on how ALAN can directly alter predation, a fundamental ecosystem process, and have indirect trophic consequences. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterization of particulate matter size distributions and indoor concentrations from kerosene and diesel lamps.

PubMed

Apple, J; Vicente, R; Yarberry, A; Lohse, N; Mills, E; Jacobson, A; Poppendieck, D

2010-10-01

Over one-quarter of the world's population relies on fuel-based lighting. Kerosene lamps are often located in close proximity to users, potentially increasing the risk for respiratory illnesses and lung cancer. Particulate matter concentrations resulting from cook stoves have been extensively studied in the literature. However, characterization of particulate concentrations from fuel-based lighting has received minimal attention. This research demonstrates that vendors who use a single simple wick lamp in high-air-exchange market kiosks will likely be exposed to PM(2.5) concentrations that are an order of magnitude greater than ambient health guidelines. Using a hurricane lamp will reduce exposure to PM(2.5) and PM(10) concentrations by an order of magnitude compared to using a simple wick lamp. Vendors using a single hurricane or pressure lamp may not exceed health standards or guidelines for PM(2.5) and PM(10), but will be exposed to elevated 0.02-0.3 μm particle concentrations. Vendors who change from fuel-based lighting to electric lighting technology for enhanced illumination will likely gain the ancillary health benefit of reduced particulate matter exposure. Vendors exposed only to ambient and fuel-based lighting particulate matter would see over an 80% reduction in inhaled PM(2.5) mass if they switched from a simple wick lamp to an electric lighting technology. Changing lighting technologies to achieve increased efficiency and energy service levels can provide ancillary health benefits. The cheapest, crudest kerosene lamps emit the largest amounts of PM(2.5). Improving affordability and access to better lighting options (hurricane or pressure lamps and lighting using grid or off-grid electricity) can deliver health benefits for a large fraction of the world's population, while reducing the economic and environmental burden of the current fuel-based lighting technologies.

3D printing cybersecurity: detecting and preventing attacks that seek to weaken a printed object by changing fill level

NASA Astrophysics Data System (ADS)

Straub, Jeremy

2017-06-01

Prior work by Zeltmann, et al. has demonstrated the impact of small defects and other irregularities on the structural integrity of 3D printed objects. It posited that such defects could be introduced intentionally. The current work looks at the impact of changing the fill level on object structural integrity. It considers whether the existence of an appropriate level of fill can be determined through visible light imagery-based assessment of a 3D printed object. A technique for assessing the quality and sufficiency of quantity of 3D printed fill material is presented. It is assessed experimentally and results are presented and analyzed.

Successional changes in functional composition contrast for dry and wet tropical forest.

PubMed

Lohbeck, Madelon; Poorter, Lourens; Lebrija-Trejos, Edwin; Martínez-Ramos, Miguel; Meave, Jorge A; Paz, Horacio; Pérez-García, Eduardo A; Romero-Pérez, I Eunice; Tauro, Alejandra; Bongers, Frans

2013-06-01

We tested whether and how functional composition changes with succession in dry deciduous and wet evergreen forests of Mexico. We hypothesized that compositional changes during succession in dry forest were mainly determined by increasing water availability leading to community functional changes from conservative to acquisitive strategies, and in wet forest by decreasing light availability leading to changes from acquisitive to conservative strategies. Research was carried out in 15 dry secondary forest plots (5-63 years after abandonment) and 17 wet secondary forest plots (< 1-25 years after abandonment). Community-level functional traits were represented by community-weighted means based on 11 functional traits measured on 132 species. Successional changes in functional composition are more marked in dry forest than in wet forest and largely characterized by different traits. During dry forest succession, conservative traits related to drought tolerance and drought avoidance decreased, as predicted. Unexpectedly acquisitive leaf traits also decreased, whereas seed size and dependence on biotic dispersal increased. In wet forest succession, functional composition changed from acquisitive to conservative leaf traits, suggesting light availability as the main driver of changes. Distinct suites of traits shape functional composition changes in dry and wet forest succession, responding to different environmental filters.

Nilsson diagrams for light neutron-rich nuclei with weakly-bound neutrons

NASA Astrophysics Data System (ADS)

Hamamoto, Ikuko

2007-11-01

Using Woods-Saxon potentials and the eigenphase formalism for one-particle resonances, one-particle bound and resonant levels for neutrons as a function of quadrupole deformation are presented, which are supposed to be useful for the interpretation of spectroscopic properties of some light neutron-rich nuclei with weakly bound neutrons. Compared with Nilsson diagrams in textbooks that are constructed using modified oscillator potentials, we point out a systematic change of the shell structure in connection with both weakly bound and resonant one-particle levels related to small orbital angular momenta ℓ. Then, it is seen that weakly bound neutrons in nuclei such as C15-19 and Mg33-37 may prefer being deformed as a result of the Jahn-Teller effect, due to the near degeneracy of the 1d5/2-2s1/2 levels and the 1f7/2-2p3/2 levels in the spherical potential, respectively. Furthermore, the absence of some one-particle resonant levels compared with the Nilsson diagrams in textbooks is illustrated.

Comparisons between bone and cementum compositions and the possible basis for their layered appearances.

PubMed

Cool, S M; Forwood, M R; Campbell, P; Bennett, M B

2002-02-01

In humans, age estimation from the adult skeleton represents an attempt to determine chronological age based on growth and maturational events. In teeth, such events can be characterized by appositional growth layers in midroot cementum. The purpose of this study was to determine the underlying cause of the layered microstructure of human midroot cementum. Whether cementum growth layers are caused by changes in relative mineralization, collagen packing and/or orientation, or by variations in organic matrix apposition was investigated by subjecting midroot sections of human canine teeth to analysis using polarized light and scanning electron microscopy (SEM). Polarized light was used to examine transverse midroot sections in both mineralized and demineralized states. Mineralized sections were also reexamined following subsequent decollagenization. Polarized light was additionally used in the examination of mineralized sections taken transversely, longitudinally, and obliquely from the same tooth root. From the birefringence patterns it was concluded that collagen orientation does not change with varying section plane. Instead, the mineral phase was most responsible for the birefringence of the cementum. SEM studies suggested that neither collagen packing nor collagen orientation change across the width of the cementum, confirming and validating the results of the polarized light examination. Also, SEM analysis using electron backscatter and the electron probe suggested no changes in the mean atomic number density, calcium, phosphate, and sulfur levels across the width of the cementum. Therefore, we conclude that crystalline orientation and/or size is responsible for the layered appearance of cementum.

Longitudinal performance of plasma neurofilament light and tau in professional fighters: The Professional Fighters Brain Health Study.

PubMed

Bernick, Charles; Zetterberg, Henrik; Shan, Guogen; Banks, Sarah; Blennow, Kaj

2018-04-02

The objective of this study is to evaluate longitudinal change in plasma neurofilament light (NF-L) and tau levels in relationship to clinical and radiological measures in professional fighters. Participants (active and retired professional fighters and control group) underwent annual blood sampling, 3 Tesla MRI brain imaging, computerized cognitive testing, and assessment of exposure to head trauma. Plasma tau and NF-L concentrations were measured using Simoa assays. Multiple linear regression models were used to compare the difference across groups in regard to baseline measurements, while mixed linear models was used for the longitudinal data with multiple measurements for each participant. Plasma samples were available on 471 participants. Baseline NF-L measures differed across groups (F_3,393=6.99, p=0.0001), with the active boxers having the highest levels. Higher NF-L levels at baseline were correlated with lower baseline MRI regional volumes and lower cognitive scores. The number of sparring rounds completed by the active fighters was correlated with NF-L (95% CI 0.0116-0.4053, p=0.0381), but not tau, levels. Among 126 subjects having multiple yearly samples, there was a significant difference in average yearly percentage change in tau across groups (F_3,83=3.87, p=0.0121).). We conclude that plasma NF-L and tau behave differently in a group of active and retired fighters; NF-L better reflects acute exposure whereas the role of plasma tau levels in signifying chronic change in brain structure over time requires further study.

Effects of day-length variations on emotional responses towards unfamiliarity in Swiss mice.

PubMed

Kopp, C; Misslin, R; Vogel, E; Rettori, M C; Delagrange, P; Guardiola-Lemaitre, B

1997-11-01

Pineal melatonin secretion occurs at night in all vertebrates and the duration of its secretion is negatively correlated with day length. As an anxiolytic activity of melatonin has been shown in rats and mice, this study examined possible changes of emotional reactivity in response to day length variations in Swiss mice. Three groups of mice were observed in a free-exploratory test: a group submitted to a short-day exposure (6:18 h light-dark cycle) for 2 weeks, a group submitted to a long-day exposure (18:6 h light-dark cycle) for 2 weeks and a control group which was maintained in housing 12:12 h light-dark cycle. The short-day exposed group of mice exhibited significantly fewer attempts to enter into the unfamiliar enclosure, spent significantly more time in it and presented significantly more rears than controls whereas the long-day exposed group of mice made more attempts than controls. These results suggest a decreased emotional level in short-day exposed mice and an increased level in long-day exposed mice. This could be interpreted as confirming the idea of anxiolytic-like properties of melatonin; however, the specific role of this hormone in the changes of anxiety related to day length must be assessed by further measures of potential variations of circulating melatonin.

Effect of low-level light therapy on diabetic foot ulcers: a near-infrared spectroscopy study

NASA Astrophysics Data System (ADS)

Salvi, Massimo; Rimini, Daniele; Molinari, Filippo; Bestente, Gianni; Bruno, Alberto

2017-03-01

Diabetic foot ulcer (DFU) is a diabetic complication due to peripheral vasculopathy and neuropathy. A promising technology for wound healing in DFU is low-level light therapy (LLLT). Despite several studies showing positive effects of LLLT on DFU, LLLT's physiological effects have not yet been studied. The objective of this study was to investigate vascular and nervous systems modification in DFU after LLLT. Two samples of 45 DFU patients and 11 healthy controls (HCs) were recruited. The total hemoglobin (totHb) concentration change was monitored before and after LLLT by near-infrared spectroscopy and analyzed in time and frequency domains. The spectral power of the totHb changes in the very-low frequency (VLF, 20 to 60 mHz) and low frequency (LF, 60 to 140 mHz) bandwidths was calculated. Data analysis revealed a mean increase of totHb concentration after LLLT in DFU patients, but not in HC. VLF/LF ratio decreased significantly after the LLLT period in DFU patients (indicating an increased activity of the autonomic nervous system), but not in HC. Eventually, different treatment intensities in LLLT therapy showed a different response in DFU. Overall, our results demonstrate that LLLT improves blood flow and autonomic nervous system regulation in DFU and the importance of light intensity in therapeutic protocols.

Nitrogen can improve the rapid response of photosynthesis to changing irradiance in rice (Oryza sativa L.) plants.

PubMed

Sun, Jiali; Ye, Miao; Peng, Shaobing; Li, Yong

2016-08-10

To identify the effect of nitrogen (N) nutrition on the dynamic photosynthesis of rice plants, a pot experiment was conducted under two N conditions. The leaf N and chlorophyll levels, as well as steady-state photosynthesis, were significantly increased under high N. After the transition from saturating to low light levels, decreases in the induction state (IS%) of leaf photosynthesis (A) and stomatal conductance (gs) were more severe under low than under high N supply. After the transition from low to flecked irradiance, the times to 90% of maximum A (T90%A) were significantly longer under low than under high N supply. Under flecked irradiance, the maximum A under saturating light (Amax-fleck) and the steady-state A under low light (Amin-fleck) were both lower than those under uniform irradiance (Asat and Ainitial). Under high N supply, Amax-fleck was 14.12% lower than Asat, while it was 22.80% lower under low N supply. The higher IS%, shorter T90%A, and the lower depression of Amax-fleck from Asat under high N supply led to a less carbon loss compared with under a low N supply. Therefore, we concluded that N can improve the rapid response of photosynthesis to changing irradiance.

Effect of low-level light therapy on diabetic foot ulcers: a near-infrared spectroscopy study.

PubMed

Salvi, Massimo; Rimini, Daniele; Molinari, Filippo; Bestente, Gianni; Bruno, Alberto

2017-03-01

Diabetic foot ulcer (DFU) is a diabetic complication due to peripheral vasculopathy and neuropathy. A promising technology for wound healing in DFU is low-level light therapy (LLLT). Despite several studies showing positive effects of LLLT on DFU, LLLT’s physiological effects have not yet been studied. The objective of this study was to investigate vascular and nervous systems modification in DFU after LLLT. Two samples of 45 DFU patients and 11 healthy controls (HCs) were recruited. The total hemoglobin (totHb) concentration change was monitored before and after LLLT by near-infrared spectroscopy and analyzed in time and frequency domains. The spectral power of the totHb changes in the very-low frequency (VLF, 20 to 60 mHz) and low frequency (LF, 60 to 140 mHz) bandwidths was calculated. Data analysis revealed a mean increase of totHb concentration after LLLT in DFU patients, but not in HC. VLF/LF ratio decreased significantly after the LLLT period in DFU patients (indicating an increased activity of the autonomic nervous system), but not in HC. Eventually, different treatment intensities in LLLT therapy showed a different response in DFU. Overall, our results demonstrate that LLLT improves blood flow and autonomic nervous system regulation in DFU and the importance of light intensity in therapeutic protocols.

Method and apparatus for thermal management of vehicle exhaust systems

DOEpatents

Benson, D.K.; Potter, T.F.

1995-12-26

A catalytic converter is surrounded by variable conductance insulation for maintaining the operating temperature of the catalytic converter at an optimum level, for inhibiting heat loss when raising catalytic converter temperature to light-off temperature, for storing excess heat to maintain or accelerate reaching light-off temperature, and for conducting excess heat away from the catalytic converter after reaching light-off temperature. The variable conductance insulation includes vacuum gas control and metal-to-metal thermal shunt mechanisms. Radial and axial shielding inhibits radiation and convection heat loss. Thermal storage media includes phase change material, and heat exchanger chambers and fluids carry heat to and from the catalytic converter. 7 figs.

Study of Laser Reflectivity on Skin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oidor-Garcia, J. J. J.; Trevino-Palacios, C. G.

2008-08-11

The response to the light on the skin can be manifested as temperature increase or creation of biochemical byproducts, in which further studies are required to asset the light effect. This response changes the average response over time and can produce discrepancies between similar studies. In this work we present a Low Level Laser Therapy (LLLT) study with feedback. We study the time response reflectivity of a 980 nm laser diode of 25 mW modulated at frequencies close to 40 kHz and detect the reflected light on a silicon photodiode, finding no direct correlation between different test points or individuals,more » while finding reproducible responses within the same individual and test point.« less

Development and field testing of a Light Aircraft Oil Surveillance System (LAOSS)

NASA Technical Reports Server (NTRS)

Burns, W.; Herz, M. J.

1976-01-01

An experimental device consisting of a conventional TV camera with a low light level photo image tube and motor driven polarized filter arrangement was constructed to provide a remote means of discriminating the presence of oil on water surfaces. This polarized light filtering system permitted a series of successive, rapid changes between the vertical and horizontal components of reflected polarized skylight and caused the oil based substances to be more easily observed and identified as a flashing image against a relatively static water surface background. This instrument was flight tested, and the results, with targets of opportunity and more systematic test site data, indicate the potential usefulness of this airborne remote sensing instrument.

Plasticity varies with boldness in a weakly-electric fish.

PubMed

Kareklas, Kyriacos; Arnott, Gareth; Elwood, Robert W; Holland, Richard A

2016-01-01

The expression of animal personality is indicated by patterns of consistency in individual behaviour. Often, the differences exhibited between individuals are consistent across situations. However, between some situations, this can be biased by variable levels of individual plasticity. The interaction between individual plasticity and animal personality can be illustrated by examining situation-sensitive personality traits such as boldness (i.e. risk-taking and exploration tendency). For the weakly electric fish Gnathonemus petersii, light condition is a major factor influencing behaviour. Adapted to navigate in low-light conditions, this species chooses to be more active in dark environments where risk from visual predators is lower. However, G. petersii also exhibit individual differences in their degree of behavioural change from light to dark. The present study, therefore, aims to examine if an increase of motivation to explore in the safety of the dark, not only affects mean levels of boldness, but also the variation between individuals, as a result of differences in individual plasticity. Boldness was consistent between a novel-object and a novel-environment situation in bright light. However, no consistency in boldness was noted between a bright (risky) and a dark (safe) novel environment. Furthermore, there was a negative association between boldness and the degree of change across novel environments, with shier individuals exhibiting greater behavioural plasticity. This study highlights that individual plasticity can vary with personality. In addition, the effect of light suggests that variation in boldness is situation specific. Finally, there appears to be a trade-off between personality and individual plasticity with shy but plastic individuals minimizing costs when perceiving risk and bold but stable individuals consistently maximizing rewards, which can be maladaptive.

Comparing phototoxicity during the development of a zebrafish craniofacial bone using confocal and light sheet fluorescence microscopy techniques.

PubMed

Jemielita, Matthew; Taormina, Michael J; Delaurier, April; Kimmel, Charles B; Parthasarathy, Raghuveer

2013-12-01

The combination of genetically encoded fluorescent proteins and three-dimensional imaging enables cell-type-specific studies of embryogenesis. Light sheet microscopy, in which fluorescence excitation is provided by a plane of laser light, is an appealing approach to live imaging due to its high speed and efficient use of photons. While the advantages of rapid imaging are apparent from recent work, the importance of low light levels to studies of development is not well established. We examine the zebrafish opercle, a craniofacial bone that exhibits pronounced shape changes at early developmental stages, using both spinning disk confocal and light sheet microscopies of fluorescent osteoblast cells. We find normal and aberrant opercle morphologies for specimens imaged with short time intervals using light sheet and spinning disk confocal microscopies, respectively, under equivalent exposure conditions over developmentally-relevant time scales. Quantification of shapes reveals that the differently imaged specimens travel along distinct trajectories in morphological space. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural changes in the vascular bundles of light-exposed and shaded spruce needles suffering from Mg deficiency and ozone pollution.

PubMed

Boxler-Baldoma, Carmen; Lütz, Cornelius; Heumann, Hans-Günther; Siefermann-Harms, Dorothea

2006-02-01

The correlation between structural changes of the vascular bundles and needle yellowing was examined for needles of damaged spruce (Picea abies (L.) Karst.) growing at a Mg-deficient and ozone polluted mountain site in the Central Black Forest (840m a.s.l.). In the previous year's sun-exposed needles, the following sequence of events was observed: (1) rapid needle yellowing, (2) hypertrophy and anomalous divisions of cambium cells, (3) phloem collapse, and, (4) production of atypical xylem tracheids. Under defined shade (reduction of the photosynthetically active photon flux density of the ambient light by 85-90%), the needles remained green, while the phloem collapsed completely within the first 6 weeks of shading; subsequently, a reversal of the collapse was observed. Under both light conditions, the content of Mg not bound to chlorophyll (Mg(free)) was in the range of 0.1 mg g(-1) needle dry matter, and hardly changed throughout the investigation period. After Mg fertilization, the Mg(free) level of the previous year's needles increased to 0.2 mg g(-1) dry matter, the light-exposed needles remained green, and the vascular bundles developed no anomalies. The data show that the rapid needle yellowing of ozone-exposed Mg-deficient needles did not depend on the collapse of the phloem. Mg deficiency played a key role in the development of anomalous vascular bundles under light, and also appears to explain the transient changes in sieve cell structure under shade. The role of Mg deficiency, rather than ozone pollution, in the damage of the sieve cells was confirmed in a long-term ozone exposure experiment with young clonal spruce growing under defined conditions.

Light therapy for multiple sclerosis-associated fatigue: Study protocol for a randomized controlled trial.

PubMed

Mateen, Farrah J; Manalo, Natalie C; Grundy, Sara J; Houghton, Melissa A; Hotan, Gladia C; Erickson, Hans; Videnovic, Aleksandar

2017-09-01

Fatigue is the most commonly reported symptom among multiple sclerosis (MS) patients, more than a quarter of whom consider fatigue to be their most disabling symptom. However, there are few effective treatment options for fatigue. We aim to investigate whether supplemental exposure to bright white light will reduce MS-associated fatigue. Eligible participants will have clinically confirmed multiple sclerosis based on the revised McDonald criteria (2010) and a score ≥36 on the Fatigue Severity Scale (FSS). Participants will be randomized 1:1 to bright white light (10,000 lux; active condition) or dim red light (<300 lux; control condition) self-administered for 1 hour twice daily. The study will include a 2-week baseline period, a 4-week treatment period, and a 4-week washout period. Participants will record their sleep duration, exercise, caffeine, and medication intake daily. Participants will record their fatigue using the Visual Analogue Fatigue Scale (VAFS) 4 times every third day, providing snapshots of their fatigue level at different times of day. Participants will self-report their fatigue severity using FSS on 3 separate visits: at baseline (week 0), following completion of the treatment phase (week 6), and at study completion (week 10). The primary outcome will be the change in the average FSS score after light therapy. We will perform an intention-to-treat analysis, comparing the active and control groups to assess the postintervention difference in fatigue levels reported on FSS. Secondary outcome measures include change in global VAFS scores during the light therapy and self-reported quality of life in the Multiple Sclerosis Quality of Life-54. We present a study design and rationale for randomizing a nonpharmacological intervention for MS-associated fatigue, using bright light therapy. The study limitations relate to the logistical issues of a self-administered intervention requiring frequent participant self-report in a relapsing condition. Ultimately, light therapy for the treatment of MS-associated fatigue may provide a low-cost, noninvasive, self-administered treatment for one of the most prevalent and burdensome symptoms experienced by people with MS.

A Programmable Optical Stimulator for the Drosophila Eye.

PubMed

Chen, Xinping; Leon-Salas, Walter D; Zigon, Taylor; Ready, Donald F; Weake, Vikki M

2017-10-01

A programmable optical stimulator for Drosophila eyes is presented. The target application of the stimulator is to induce retinal degeneration in fly photoreceptor cells by exposing them to light in a controlled manner. The goal of this work is to obtain a reproducible system for studying age-related changes in susceptibility to environmental ocular stress. The stimulator uses light emitting diodes and an embedded computer to control illuminance, color (blue or red) and duration in two independent chambers. Further, the stimulator is equipped with per-chamber light and temperature sensors and a fan to monitor light intensity and to control temperature. An ON/OFF temperature control implemented on the embedded computer keeps the temperature from reaching levels that will induce the heat shock stress response in the flies. A custom enclosure was fabricated to house the electronic components of the stimulator. The enclosure provides a light-impermeable environment that allows air flow and lets users easily load and unload fly vials. Characterization results show that the fabricated stimulator can produce light at illuminances ranging from 0 to 16000 lux and power density levels from 0 to 7.2 mW/cm 2 for blue light. For red light the maximum illuminance is 8000 lux which corresponds to a power density of 3.54 mW/cm 2 . The fans and the ON/OFF temperature control are able to keep the temperature inside the chambers below 28.17°C. Experiments with white-eye male flies were performed to assess the ability of the fabricated simulator to induce blue light-dependent retinal degeneration. Retinal degeneration is observed in flies exposed to 8 hours of blue light at 7949 lux. Flies in a control experiment with no light exposure show no retinal degeneration. Flies exposed to red light for the similar duration and light intensity (8 hours and 7994 lux) do not show retinal degeneration either. Hence, the fabricated stimulator can be used to create environmental ocular stress using blue light.

Polydiacetylenes: An Ideal Color System for Teaching Polymer Science.

ERIC Educational Resources Information Center

Patel, Gordhan N.; Yang, Nan-Loh

1983-01-01

Describes 14 experiments that illustrate, via color changes, a broad scope of fundamental phenomena in polymer science. The experiments, suitable for high school through graduate level, require only test tubes, filter paper, heat source (hot plate or hair drier), and ultra-violet light source. (JN)

Auxin-to-Gibberellin Ratio as a Signal for Light Intensity and Quality in Regulating Soybean Growth and Matter Partitioning

PubMed Central

Yang, Feng; Fan, Yuanfang; Wu, Xiaoling; Cheng, Yajiao; Liu, Qinlin; Feng, Lingyang; Chen, Junxu; Wang, Zhonglin; Wang, Xiaochun; Yong, Taiwen; Liu, Weiguo; Liu, Jiang; Du, Junbo; Shu, Kai; Yang, Wenyu

2018-01-01

The intensity and quality (red to far-red (R/Fr) ratio) of light directly affect growth of plant under shading. Gibberellins (GAs) and auxin [indole-3-acetic acid (IAA)] play important roles in mediating the shading adaptive responses of plants. Thus, the intensity and quality of the uncoupling light from shading were assessed to identify the influence of each component on the morphology and matter distribution of the leaf, stem, and petiole. This assessment was based on the changes in endogenous Gibberellin 1 (GA1) and IAA levels. Soybean plants were grown in a growth chamber with four treatments [normal (N), N+Fr, low (L), and L+Fr light]. Results revealed that the reductions in photosynthetically active radiation (PAR) and R/Fr ratio equally increased height and stem mass fractions (SMFs) of the soybean seedling. The light intensity significantly influenced the dry mass per unit area and mass fraction of soybean leaves, whereas the light quality regulated the petiole elongation and mass fraction. Low R/Fr ratio (high Fr light) increased the soybean biomass by improving the photosynthetic assimilation rate and quantum yield of photosystem II. In addition, the IAA and GA1 levels in the leaf, stem, and petiole did not reflect the growth response trends of each tissue toward light intensity and quality; however, trends of the IAA-to-GA1 content ratios were similar to those of the growth and matter allocation of each soybean tissue under different light environments. Therefore, the response of growth and matter allocation of soybean to light intensity and quality may be regulated by the IAA-to-GA1 content ratio in the tissues of the soybean plant. PMID:29441084

Acupuncture attenuates hyperglycaemia and improves ovarian function in female rats subjected to continuous light exposure.

PubMed

Kang, Xuezhi; Jia, Lina; Li, Yaming; Zhang, Xu

2017-10-01

Exposure to unnatural light cycles is increasingly associated with obesity and the metabolic syndrome. The purpose of this study was to examine the effects of electroacupuncture (EA) on glucose metabolism and ovarian function in female rats subjected to long-term continuous light exposure. Female Sprague-Dawley rats (n=24) were divided into three experimental groups: an LD group that was maintained under a normal light-dark cycle (healthy control); an LL group that was exposed to continuous light for 21 weeks but remained untreated; and an LL+EA group that received EA at ST36 and SP6 during weeks 17 to 21 of continuous light exposure. Oestrous cycles of female rats kept in a continuously lit environment for 21 weeks were disordered and polycystic ovarian syndrome (PCOS)-like changes occurred, accompanied by increased fasting blood glucose (6.23±0.33 vs 5.27±0.40 mmol/L in week 17, p=0.015) and reduced fasting levels of serum testosterone (0.07±0.018 vs 0.12±0.058 ng/L, p=0.043) and insulin (0.89±0.20 vs 1.43±0.46 ng/L, p=0.006). After 5 weeks of EA treatment at ST36 and SP6, ovarian cycle disruption was mitigated and blood glucose levels showed a gradual decline (5.18±0.37 vs 5.80±0.55 mmol/L, p=0.017; and 5.73±0.31 vs 6.62±0.13 mmol/L, p=0.004; in the fourth and fifth weeks of EA treatment, respectively). EA also attenuated the reductions otherwise seen in serum insulin and testosterone levels. Prolonged exposure to light can lead to a decline in ovarian and pancreatic function. EA at ST36 and SP6 may reduce abnormally elevated blood glucose levels and improve ovarian and pancreatic hormone levels. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Studies on the mechanism of photodynamic-therapy-induced tumor destruction

NASA Astrophysics Data System (ADS)

Fingar, Victor H.; Wieman, Thomas J.

1990-07-01

There exists little doubt that profound changes occur to both tumor and normal tissue microvasculature during photodynamic therapy, and that these changes are important in the process of tumor destruction. We hypothesize that singlet oxygen, produced during light activation of photosensitizer, interacts with cellular membranes and induces the release of arachidonic acid metabolites, notably thromboxane, into the intravascular environment. This leads to vasoconstriction, platelet aggregation, and hemostasis. To test this hypothesis, we have measured the release of thromboxane into serum as a function of porphyrin and light doses used in phototherapy. Sprague Dawley rats bearing chondrosarcoma in the right hind limb were injected with 0-25 mg/kg Photofrin IP'. A catheter was implanted in the carotid artery 24 h later, and the hind limb exposed to 0-135 J/cm2 630 nm light. Immediately after treatment, serum was collected and thromboxane levels were measured by radioimmunoassay. We found significant increases in systemic thromboxane concentrations following phototherapy at the highest porphyrin and light doses, compared to drug and light controls. The administration of indomethacin (10 mg/kg i.p.) prior to treatment suppressed the release of thromboxane from tumor and normal tissues and inhibited hemostasis and tumor response to phototherapy. These studies have reinforced the important role of arachidonic acid metabolites in producing vascular damage during phototherapy.

Mapping and Evaluating the Urbanization Process in Northeast China Using DMSP/OLS Nighttime Light Data

PubMed Central

Yi, Kunpeng; Tani, Hiroshi; Li, Qiang; Zhang, Jiquan; Guo, Meng; Bao, Yulong; Wang, Xiufeng; Li, Jing

2014-01-01

In this paper, an Urban Light Index (ULI) is constructed to facilitate analysis and quantitative evaluation of the process of urbanization and expansion rate by using DMSP/OLS Nighttime Light Data during the years from 1992 to 2010. A unit circle urbanization evaluation model is established to perform a comprehensive analysis of the urbanization process of 34 prefecture-level cities in Northeast China. Furthermore, the concept of urban light space is put forward. In this study, urban light space is divided into four types: the core urban area, the transition zone between urban and suburban areas, suburban area and fluorescent space. Proceeding from the temporal and spatial variation of the four types of light space, the pattern of morphologic change and space-time evolution of the four principal cities in Northeast China (Harbin, Changchun, Shenyang, Dalian) is analyzed and given particular attention. Through a correlation analysis between ULI and the traditional urbanization indexes (urban population, proportion of the secondary and tertiary industries in the regional GDP and the built-up area), the advantages and disadvantages as well as the feasibility of using the ULI in the study of urbanization are evaluated. The research results show that ULI has a strong correlation with urban built-up area (R2 = 0.8277). The morphologic change and history of the evolving urban light space can truly reflect the characteristics of urban sprawl. The results also indicate that DMSP/OLS Nighttime Light Data is applicable for extracting urban space information and has strong potential to urbanization research. PMID:24553086

Different levels of brain-derived neurotrophic factor and cortisol in healthy heavy smokers.

PubMed

Neves, C D C; Lacerda, A C R; Lima, L P; Lage, V K S; Balthazar, C H; Leite, H R; Mendonça, V A

2017-10-19

Studies suggest that brain-derived neurotrophic factor (BDNF) and the hypothalamic-pituitary-adrenal (HPA) axis modulate dopaminergic activity in response to nicotine and that the concentrations of BDNF and cortisol seem to be dependent on the amount and duration of smoking. Therefore, we investigated BDNF and cortisol levels in smokers ranked by daily cigarette consumption. Twenty-seven adult males (13 non-smokers and 14 smokers) participated in the study. The smokers were divided in two groups: light (n=7) and heavy smokers (n=7). Anthropometric parameters and age were paired between the groups, and plasma BDNF and salivary cortisol levels were measured. Saliva samples were collected on awakening, 30 min after awakening, at 10:00 and 12:00 am, 5:00 and 10:00 pm. Additionally, cotinine serum levels were measured in smokers. Heavy smokers had higher mean values of BDNF compared to the control group (P=0.01), whereas no difference was observed in light smokers. Moreover, heavy smokers presented lower cortisol levels in the last collection (10:00 pm) than the control group (P=0.02) and presented statically higher values of cotinine than the light smokers (P=0.002). In conclusion, changes in BDNF and cortisol levels (10:00 pm) appear to be dependent on heavy cigarette smoking and can be involved in activation and in the relationship between the mesolimbic system and the HPA axis.

Different levels of brain-derived neurotrophic factor and cortisol in healthy heavy smokers

PubMed Central

Neves, C.D.C.; Lacerda, A.C.R.; Lima, L.P.; Lage, V.K.S.; Balthazar, C.H.; Leite, H.R.; Mendonça, V.A.

2017-01-01

Studies suggest that brain-derived neurotrophic factor (BDNF) and the hypothalamic-pituitary-adrenal (HPA) axis modulate dopaminergic activity in response to nicotine and that the concentrations of BDNF and cortisol seem to be dependent on the amount and duration of smoking. Therefore, we investigated BDNF and cortisol levels in smokers ranked by daily cigarette consumption. Twenty-seven adult males (13 non-smokers and 14 smokers) participated in the study. The smokers were divided in two groups: light (n=7) and heavy smokers (n=7). Anthropometric parameters and age were paired between the groups, and plasma BDNF and salivary cortisol levels were measured. Saliva samples were collected on awakening, 30 min after awakening, at 10:00 and 12:00 am, 5:00 and 10:00 pm. Additionally, cotinine serum levels were measured in smokers. Heavy smokers had higher mean values of BDNF compared to the control group (P=0.01), whereas no difference was observed in light smokers. Moreover, heavy smokers presented lower cortisol levels in the last collection (10:00 pm) than the control group (P=0.02) and presented statically higher values of cotinine than the light smokers (P=0.002). In conclusion, changes in BDNF and cortisol levels (10:00 pm) appear to be dependent on heavy cigarette smoking and can be involved in activation and in the relationship between the mesolimbic system and the HPA axis. PMID:29069228

Effects of microgravity on muscle and cerebral cortex: a suggested interaction

NASA Astrophysics Data System (ADS)

D'Amelio, F.; Fox, R. A.; Wu, L. C.; Daunton, N. G.; Corcoran, M. L.

The ``slow'' antigravity muscle adductor longus was studied in rats after 14 days of spaceflight (SF). The techniques employed included standard methods for light microscopy, neural cell adhesion molecule (N-CAM) immunocytochemistry and electron microscopy. Light and electron microscopy revealed myofiber atrophy, segmental necrosis and regenerative myofibers. Regenerative myofibers were N-CAM immunoreactive (N-CAM-IR). The neuromuscular junctions showed axon terminals with a decrease or absence of synaptic vesicles, degenerative changes, vacant axonal spaces and changes suggestive of axonal sprouting. No alterations of muscle spindles was seen either by light or electron microscopy. These observations suggest that muscle regeneration and denervation and synaptic remodeling at the level of the neuromuscular junction may take place during spaceflight. In a separate study, GABA immunoreactivity (GABA-IR) was evaluated at the level of the hindlimb representation of the rat somatosensory cortex after 14 days of hindlimb unloading by tail suspension (``simulated'' microgravity). A reduction in number of GABA-immunoreactive cells with respect to the control animals was observed in layer Va and Vb. GABA-IR terminals were also reduced in the same layers, particularly those terminals surrounding the soma and apical dendrites of pyramidal cells in layer Vb. On the basis of previous morphological and behavioral studies of the neuromuscular system after spaceflight and hindlimb suspension it is suggested that after limb unloading there are alterations of afferent signaling and feedback information from intramuscular receptors to the cerebral cortex due to modifications in the reflex organization of hindlimb muscle groups. We propose that the changes observed in GABA immunoreactivity of cells and terminals is an expression of changes in their modulatory activity to compensate for the alterations in the afferent information.

[Effects of short-term continuous lighting with LED lamps and nitrogen nutrition conditions on quality of hydroponically grown purple lettuce].

PubMed

Yu, Yi; Yang, Qi-chang; Liu, Wen-ke

2015-11-01

Purple lettuce was grown hydroponically under six different nitrogen nutrition conditions, with NO(3-)-N:NH(4+)-N at 1:0, 4:1 and 1:1 combined with nitrogen application levels of 10 and 15 mmol · L(-1), for 25 days in solar greenhouse, then treated with short-term continuous lighting (SCL) before harvest to study the changes in contents of nutrients and analyze the effects of nitrogen nutrition conditions on the changes. Results showed that the shoot dry mass of all six nitrogen nutrition conditions were significantly improved under SCL treatment, by 35.1% at least, and the root dry mass increased greatly except for NO(3-)-N:NH(4+)-N 1:1 combined with nitrogen application level 15 mmol · L(-1) treatment and NO(3-)-N:NH(4+)-N 1:0 combined with nitrogen application level 10 mmol · L(-1) treatment. The relative contents of total phenols and flavonoid of different nitrogen nutrition conditions turned significantly different after treatment with SCL. The relative contents of total phenols and flavonoid were enhanced with the improvement of ammonium nitrogen ratio, while the relative content of anthocyanin increased and then decreased with the improvement of ammonium nitrogen ratio. The lighting treatment reduced the nitrate content of leaf blade of all six nitrogen nutrition conditions remarkably by 23.2% at least. The contents of ascorbic acid, soluble sugar and soluble protein rose significantly under SCL treatments. The study showed that the reduction of nitrate content speeded up with the enhancement of nitrogen application level and ammonium nitrogen ratio, and the advancement of ascorbic acid content slowed down with the increasing nitrogen application level. The soluble sugar improvement speed increased with the increasing ammonium nitrogen ratio, and SCL lifted the dry mass of the lettuce greatly. The results showed that SCL with LED lamps improved significantly the dry matter of lettuce under different nitrogen nutrition conditions, reduced the nitrate content and increased the ascorbic acid, soluble sugar and soluble protein contents greatly. In addition, nitrogen nutrition conditions affected the effectiveness of short-term continuous lighting on quality improvement rate of hydroponic lettuce remarkably.

The Effect of Differences in Day and Night Lighting Distributions on Drivers' Speed Perception.

PubMed

Kim, Jonathan D; Perrone, John A; Isler, Robert B

2017-06-01

Previous research has shown that changes to contrast levels in the visual environment caused by fog can affect drivers' perceptions of speed. It is not easy, however, to extrapolate these results to other driving scenarios in which contrast is affected, such as during nighttime driving, because the measure of contrast is more complex when considering factors such as the illumination provided by headlights. Therefore, we investigated the differences in lighting distribution patterns between day- and nighttime driving on speed perception using prerendered 3D scenarios representing driving on a rural road. A two-alternative forced-choice design based on the method of constant stimuli was utilised, with 32 participants viewing a series of pairs of scenarios (day vs. night driving) from a driver's perspective while indicating for each pair whether the second scenario was faster or slower than the first scenario. Our results indicated that speed discrimination accuracy was minimally affected by changes in lighting distribution patterns between day and night.

Changes in serotonin receptors in different brain regions after light exposure of dark-reared rats.

PubMed

Murphy, S; Uzbekov, M G; Rose, S P

1980-05-01

Male rats dark-reared from birth until 50 days of age and then exposed to light for 3 h show significant increases in specific [3H]serotonin (5-[3H]HT) binding to P2 membranes from visual and motor cortex and superior colliculus (25, 65 and 23% respectively) as compared with normal and dark-reared littermates. These increases are transient and return to normal levels after 7 days. The role of 5-HT as a transmitter in the visual system is discussed.

Color image processing and vision system for an automated laser paint-stripping system

NASA Astrophysics Data System (ADS)

Hickey, John M., III; Hise, Lawson

1994-10-01

Color image processing in machine vision systems has not gained general acceptance. Most machine vision systems use images that are shades of gray. The Laser Automated Decoating System (LADS) required a vision system which could discriminate between substrates of various colors and textures and paints ranging from semi-gloss grays to high gloss red, white and blue (Air Force Thunderbirds). The changing lighting levels produced by the pulsed CO2 laser mandated a vision system that did not require a constant color temperature lighting for reliable image analysis.

Energy Optimization on the Battlefield: How Integrating Energy Efficient Technologies at the Tactical Level Can Reduce Fuel Consumption and Lessen the Burden of Fuel Logistics

DTIC Science & Technology

2014-06-13

a kill zone. This also created maintenance issues including diesel soot buildup in the vehicles exhaust systems. Since it took three to four days to...cost savings when summed over the thousands of light fixtures used on bases and FOBs. Changing to LEDs in tents and installing motion sensors could...CFL systems. Motion sensors also aided in turning lights off when the tents 78 are not occupied. Both LEDs and motion sensors produced significant

Pollutant tracking for 3 Western North Atlantic sea grasses by remote sensing: Preliminary diminishing white light responses of Thalassia testudinum, Halodule wrightii, and Zostera marina.

PubMed

Thorhaug, Anitra; Berlyn, Graeme P; Poulos, Helen M; Goodale, Uromi M

2015-08-15

Sea grasses are foundation species for estuarine ecosystems. The available light for sea grasses diminishes rapidly during pollutant spills, effluent releases, disturbances such as intense riverine input, and tidal changes. We studied how sea grasses' remote-sensing signatures and light-capturing ability respond to short term light alterations. In vivo responses were measured over the entire visible-light spectra to diminishing white-light on whole-living-plants' spectral reflectance, including 6h of full oceanic-light fluences from 10% to 100%. We analyzed differences by various reflectance indices. We compared the sea grasses species responses of tropical vs. temperate and intertidals (Halodule wrightii, and Zostera marina) vs. subtidal (Thalassia testudinum). Reflectance diminished with decreasing light intensity that coincided with greater accessory pigment stimulation (anthocyanin, carotenoids, xanthins). Chlorophyll a and Chlorophyll b differed significantly among species (Thalassia vs. Halodule). Photosynthetic efficiency diminished at high light intensities. The NDVI index was inadequate to perceive these differences. Our results demonstrate the leaf-level utility of data to remote sensing for mapping sea grass and sea grass stress. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nitric oxide measurements in hTERT-RPE cells and subcellular fractions exposed to low levels of red light

NASA Astrophysics Data System (ADS)

Wigle, Jeffrey C.; Castellanos, Cherry C.; Denton, Michael L.; Holwitt, Eric A.

2014-02-01

Cells in a tissue culture model for laser eye injury exhibit increased resistance to a lethal pulse of 2.0-μm laser radiation if the cells are first exposed to 2.88 J/cm2 of red light 24 hr prior to the lethal laser exposure. Changes in expression of various genes associated with apoptosis have been observed, but the biochemical link between light absorption and gene expression remains unknown. Cytochome c oxidase (CCOX), in the electron transport chain, is the currentlyhypothesized absorber. Absorption of the red light by CCOX is thought to facilitate displacement of nitric oxide (NO) by O2 in the active site, increasing cellular respiration and intracellular ATP. However, NO is also an important regulator and mediator of numerous physiological processes in a variety of cell and tissue types that is synthesized from l-arginine by NO synthases. In an effort to determine the relative NO contributions from these competing pathways, we measured NO levels in whole cells and subcellular fractions, with and without exposure to red light, using DAF-FM, a fluorescent dye that stoichiometrically reacts with NO. Red light induced a small, but consistently reproducible, increase in fluorescence intensity in whole cells and some subcellular fractions. Whole cells exhibited the highest overall fluorescence intensity followed by (in order) cytosolic proteins, microsomes, then nuclei and mitochondria.

Measuring the Photocatalytic Breakdown of Crystal Violet Dye using a Light Emitting Diode Approach

NASA Technical Reports Server (NTRS)

Ryan, Robert E.; Underwood, Lauren W.; O'Neal, Duane; Pagnutti, Mary; Davis, Bruce A.

2009-01-01

A simple method to estimate the photocatalytic reactivity performance of spray-on titanium dioxide coatings for transmissive glass surfaces was developed. This novel technique provides a standardized method to evaluate the efficiency of photocatalytic material systems over a variety of illumination levels. To date, photocatalysis assessments have generally been conducted using mercury black light lamps. Illumination levels for these types of lamps are difficult to vary, consequently limiting their use for assessing material performance under a diverse range of simulated environmental conditions. This new technique uses an ultraviolet (UV) gallium nitride (GaN) light emitting diode (LED) array instead of a traditional black light to initiate and sustain photocatalytic breakdown. This method was tested with a UV-resistant dye (crystal violet) applied to a titanium dioxide coated glass slide. Experimental control is accomplished by applying crystal violet to both titanium dioxide coated slides and uncoated control slides. A slide is illuminated by the UV LED array, at various light levels representative of outdoor and indoor conditions, from the dye side of the slide. To monitor degradation of the dye over time, a temperature-stabilized white light LED, whose emission spectrum overlaps with the dye absorption spectrum, is used to illuminate the opposite side of the slide. Using a spectrometer, the amount of light from the white light LED transmitted through the slide as the dye degrades is monitored as a function of wavelength and time and is subsequently analyzed. In this way, the rate of degradation for photocatalytically coated versus uncoated slide surfaces can be compared. Results demonstrate that the dye absorption decreased much more rapidly on the photocatalytically coated slides than on the control uncoated slides, and that dye degradation is dependent on illumination level. For photocatalytic activity assessment purposes, this experimental configuration and methodology minimizes many external variable effects and enables small changes in absorption to be measured. This research also compares the advantages of this innovative LED light source design over traditional mercury black light systems and non- LED lamp approaches. This novel technology begins to address the growing need for a standard method that can assess the performance of photocatalytic materials before deployment for large scale, real world use.

Decadal-timescale estuarine geomorphic change under future scenarios of climate and sediment supply

USGS Publications Warehouse

Ganju, N.K.; Schoellhamer, D.H.

2010-01-01

Future estuarine geomorphic change, in response to climate change, sea-level rise, and watershed sediment supply, may govern ecological function, navigation, and water quality. We estimated geomorphic changes in Suisun Bay, CA, under four scenarios using a tidal-timescale hydrodynamic/sediment transport model. Computational expense and data needs were reduced using the morphological hydrograph concept and the morphological acceleration factor. The four scenarios included (1) present-day conditions; (2) sea-level rise and freshwater flow changes of 2030; (3) sea-level rise and decreased watershed sediment supply of 2030; and (4) sea-level rise, freshwater flow changes, and decreased watershed sediment supply of 2030. Sea-level rise increased water levels thereby reducing wave-induced bottom shear stress and sediment redistribution during the wind-wave season. Decreased watershed sediment supply reduced net deposition within the estuary, while minor changes in freshwater flow timing and magnitude induced the smallest overall effect. In all future scenarios, net deposition in the entire estuary and in the shallowest areas did not keep pace with sea-level rise, suggesting that intertidal and wetland areas may struggle to maintain elevation. Tidal-timescale simulations using future conditions were also used to infer changes in optical depth: though sea-level rise acts to decrease mean light irradiance, decreased suspended-sediment concentrations increase irradiance, yielding small changes in optical depth. The modeling results also assisted with the development of a dimensionless estuarine geomorphic number representing the ratio of potential sediment import forces to sediment export forces; we found the number to be linearly related to relative geomorphic change in Suisun Bay. The methods implemented here are widely applicable to evaluating future scenarios of estuarine change over decadal timescales. ?? The Author(s) 2009.

Phenotypic plasticity of sun and shade ecotypes of Stellaria longipes in response to light quality signaling, gibberellins and auxin.

PubMed

Kurepin, Leonid V; Pharis, Richard P; Neil Emery, R J; Reid, David M; Chinnappa, C C

2015-09-01

Stellaria longipes plant communities (ecotypes) occur in several environmentally distinct habitats along the eastern slopes of southern Alberta's Rocky Mountains. One ecotype occurs in a prairie habitat at ∼1000 m elevation where Stellaria plants grow in an environment in which the light is filtered by taller neighbouring vegetation, i.e. sunlight with a low red to far-red (R/FR) ratio. This ecotype exhibits a high degree of phenotypic plasticity by increasing stem elongation in response to the low R/FR ratio light signal. Another Stellaria ecotype occurs nearby at ∼2400 m elevation in a much cooler alpine habitat, one where plants rarely experience low R/FR ratio shade light. Stem elongation of plants is largely regulated by gibberellins (GAs) and auxin, indole-3-acetic acid (IAA). Shoots of the prairie ecotype plants show increased IAA levels under low R/FR ratio light and they also increase their stem growth in response to applied IAA. The alpine ecotype plants show neither response. Plants from both ecotypes produce high levels of growth-active GA1 under low R/FR ratio light, though they differ appreciably in their catabolism of GA1. The alpine ecotype plants exhibit very high levels of GA8, the inactive product of GA1 metabolism, under both normal and low R/FR ratio light. Alpine origin plants may de-activate GA1 by conversion to GA8 via a constitutively high level of expression of the GA2ox gene, thereby maintaining their dwarf phenotype and exhibiting a reduced phenotypic plasticity in terms of shoot elongation. In contrast, prairie plants exhibit a high degree of phenotypic plasticity, using low R/FR ratio light-mediated changes in GA and IAA concentrations to increase shoot elongation, thereby accessing direct sunlight to optimize photosynthesis. There thus appear to be complex adaptation strategies for the two ecotypes, ones which involve modifications in the homeostasis of endogenous hormones. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Dawn song in natural and artificial continuous day: Light pollution affects songbirds at high latitudes.

PubMed

Derryberry, Elizabeth P

2017-10-01

In Focus: Da Silva, A., & Kempenaers, B. (2017). Singing from North to South: Latitudinal variation in timing of dawn singing under natural and artificial light conditions. Journal of Animal Ecology, 86, 1286-1297. doi: 10.1111/1365-2656.12739 Satellite images of the world at night show bright dots connected by glowing lines crisscrossing the globe. As these connect-the-dots become brighter and expand into more and more remote regions, much of the flora and fauna of the world are experiencing evolutionarily unprecedented levels of light at night. Light cues are essential to most physiological and behavioural processes, and so the need to measure the effects of light pollution on these processes is critical. In this issue, Da Silva and Kempenaers take on this task using an important reproductive behaviour in songbirds-dawn song. The geographic, temporal and taxonomic breadth of sampling in this study allows for a close examination of a potentially complex interaction between light pollution and natural variation in the behaviour of dawn singing across latitude, season and species. Their extensive dataset highlights complexity in how songbirds respond to light pollution. Although light pollution has a strong effect on the timing of dawn song, not all songbirds respond the same way to light pollution, and the effects of light pollution vary with changes in natural light levels. Early dawn singers show more flexibility in the timing of dawn song across the season and across latitudes than late dawn singers, and also appear less affected by light pollution at high latitudes than are late dawn singers. These findings suggest that not all songbirds are responding to artificial continuous daylight as they do to natural continuous daylight, highlighting the general need to measure the fitness effects of light pollution. © 2017 The Author. Journal of Animal Ecology © 2017 British Ecological Society.

Reduced flight-to-light behaviour of moth populations exposed to long-term urban light pollution

PubMed Central

Ebert, Dieter

2016-01-01

The globally increasing light pollution is a well-recognized threat to ecosystems, with negative effects on human, animal and plant wellbeing. The most well-known and widely documented consequence of light pollution is the generally fatal attraction of nocturnal insects to artificial light sources. However, the evolutionary consequences are unknown. Here we report that moth populations from urban areas with high, globally relevant levels of light pollution over several decades show a significantly reduced flight-to-light behaviour compared with populations of the same species from pristine dark-sky habitats. Using a common garden setting, we reared moths from 10 different populations from early-instar larvae and experimentally compared their flight-to-light behaviour under standardized conditions. Moths from urban populations had a significant reduction in the flight-to-light behaviour compared with pristine populations. The reduced attraction to light sources of ‘city moths' may directly increase these individuals' survival and reproduction. We anticipate that it comes with a reduced mobility, which negatively affects foraging as well as colonization ability. As nocturnal insects are of eminent significance as pollinators and the primary food source of many vertebrates, an evolutionary change of the flight-to-light behaviour thereby potentially cascades across species interaction networks. PMID:27072407

Reduced flight-to-light behaviour of moth populations exposed to long-term urban light pollution.

PubMed

Altermatt, Florian; Ebert, Dieter

2016-04-01

The globally increasing light pollution is a well-recognized threat to ecosystems, with negative effects on human, animal and plant wellbeing. The most well-known and widely documented consequence of light pollution is the generally fatal attraction of nocturnal insects to artificial light sources. However, the evolutionary consequences are unknown. Here we report that moth populations from urban areas with high, globally relevant levels of light pollution over several decades show a significantly reduced flight-to-light behaviour compared with populations of the same species from pristine dark-sky habitats. Using a common garden setting, we reared moths from 10 different populations from early-instar larvae and experimentally compared their flight-to-light behaviour under standardized conditions. Moths from urban populations had a significant reduction in the flight-to-light behaviour compared with pristine populations. The reduced attraction to light sources of 'city moths' may directly increase these individuals' survival and reproduction. We anticipate that it comes with a reduced mobility, which negatively affects foraging as well as colonization ability. As nocturnal insects are of eminent significance as pollinators and the primary food source of many vertebrates, an evolutionary change of the flight-to-light behaviour thereby potentially cascades across species interaction networks. © 2016 The Author(s).

Astronomy Activities for the Classroom.

ERIC Educational Resources Information Center

Cain, Peggy W.; Welch, Daniel W.

Presented are middle school level, activity-oriented astronomy activities developed as a result of an earth science workshop for teachers. Topics include: (1) sun and moon position and measurement; (2) daily, yearly, and seasonal changes in the sun's position; (3) shapes and positions of planetary orbits; (4) eclipses; (5) properties of light; (6)…

Chemiluminescent Oscillating Demonstrations: The Chemical Buoy, the Lighting Wave, and the Ghostly Cylinder

ERIC Educational Resources Information Center

Prypsztejn, Hernan E.; Mulford, Douglas R.; Stratton, Doug

2005-01-01

Oscillating reactions have been extensively used in chemical demonstrations. They involve several chemical concepts about kinetics, catalysts, and thermodynamics. The spontaneous cyclic color change of a solution is an attraction in any educational-level course. Chemiluminescent reactions are also among the most fascinating demonstrations and have…

Leaf Stomata as Bioindicators: Stimulating Student Research

ERIC Educational Resources Information Center

Case, Steven B.

2006-01-01

Stomata are the pores on leaves through which carbon dioxide, oxygen, and water vapor are exchanged with the atmosphere. Researchers have found that leaf stomatal densities change in response to several environmental variables, including humidity, light intensity, and atmospheric levels of carbon dioxide, a greenhouse gas (Van Der Burgh, Dilcher,…

Proteomic analysis of a model unicellular green alga, Chlamydomonas reinhardtii, during short-term exposure to irradiance stress reveals significant down regulation of several heat-shock proteins.

PubMed

Mahong, Bancha; Roytrakul, Suttiruk; Phaonaklop, Narumon; Wongratana, Janewit; Yokthongwattana, Kittisak

2012-03-01

Oxygenic photosynthetic organisms often suffer from excessive irradiance, which cause harmful effects to the chloroplast proteins and lipids. Photoprotection and the photosystem II repair processes are the mechanisms that plants deploy to counteract the drastic effects from irradiance stress. Although the protective and repair mechanisms seemed to be similar in most plants, many species do confer different level of tolerance toward high light. Such diversity may originate from differences at the molecular level, i.e., perception of the light stress, signal transduction and expression of stress responsive genes. Comprehensive analysis of overall changes in the total pool of proteins in an organism can be performed using a proteomic approach. In this study, we employed 2-DE/LC-MS/MS-based comparative proteomic approach to analyze total proteins of the light sensitive model unicellular green alga Chlamydomonas reinhardtii in response to excessive irradiance. Results showed that among all the differentially expressed proteins, several heat-shock proteins and molecular chaperones were surprisingly down-regulated after 3-6 h of high light exposure. Discussions were made on the possible involvement of such down regulation and the light sensitive nature of this model alga.

Isoprenoid emission response to changing light conditions of English oak, European beech and Norway spruce

NASA Astrophysics Data System (ADS)

van Meeningen, Ylva; Schurgers, Guy; Rinnan, Riikka; Holst, Thomas

2017-09-01

Light is an important environmental factor controlling biogenic volatile organic compound (BVOC) emissions, but in natural conditions its impact is hard to separate from other influential factors such as temperature. We studied the light response of foliar BVOC emissions, photosynthesis and stomatal conductance on three common European tree species, namely English oak (Quercus robur), European beech (Fagus sylvatica) and two provenances of Norway spruce (Picea abies) in Taastrup, Denmark. Leaf scale measurements were performed on the lowest positioned branches of the tree in July 2015. Light intensity was increased in four steps (0, 500, 1000 and 1500 µmol m-2 s-1), whilst other chamber conditions such as temperature, humidity and CO2 levels were fixed. Whereas the emission rate differed between individuals of the same species, the relative contributions of compounds to the total isoprenoid emission remained similar. Whilst some compounds were species specific, the compounds α-pinene, camphene, 3-carene, limonene and eucalyptol were emitted by all of the measured tree species. Some compounds, like isoprene and sabinene, showed an increasing emission response with increasing light intensity, whereas other compounds, like camphene, had no significant emission response to light for most of the measured trees. English oak and European beech showed high light-dependent emission fractions from isoprene and sabinene, but other emitted compounds were light independent. For the two provenances of Norway spruce, the compounds α-pinene, 3-carene and eucalyptol showed high light-dependent fractions for many of the measured trees. This study highlights differences between compound emissions in their response to a change in light and a possible light independence for certain compounds, which might be valid for a wider range of tree species. This information could be of importance when improving emission models and to further emphasize the discussion regarding light or temperature dependencies for individual compounds across species.

Induction of a carbon-starvation-related proteolysis in whole maize plants submitted to Light/Dark cycles and to extended darkness

PubMed

Brouquisse; Gaudillere; Raymond

1998-08-01

Three-week-old maize (Zea mays L.) plants were submitted to light/dark cycles and to prolonged darkness to investigate the occurrence of sugar-limitation effects in different parts of the whole plant. Soluble sugars fluctuated with light/dark cycles and dropped sharply during extended darkness. Significant decreases in protein level were observed after prolonged darkness in mature roots, root tips, and young leaves. Glutamine and asparagine (Asn) changed in opposite ways, with Asn increasing in the dark. After prolonged darkness the increase in Asn accounted for most of the nitrogen released by protein breakdown. Using polyclonal antibodies against a vacuolar root protease previously described (F. James, R. Brouquisse, C. Suire, A. Pradet, P. Raymond [1996] Biochem J 320: 283-292) or the 20S proteasome, we showed that the increase in proteolytic activities was related to an enrichment of roots in the vacuolar protease, with no change in the amount of 20S proteasome in either roots or leaves. Our results show that no significant net proteolysis is induced in any part of the plant during normal light/dark cycles, although changes in metabolism and growth appear soon after the beginning of the dark period, and starvation-related proteolysis probably appears in prolonged darkness earlier in sink than in mature tissues.

The influence of intermittent fasting on the circadian pattern of melatonin while controlling for caloric intake, energy expenditure, light exposure, and sleep schedules: A preliminary report.

PubMed

Almeneessier, Aljohara S; Bahammam, Ahmed S; Sharif, Munir M; Bahammam, Salman A; Nashwan, Samar Z; Pandi Perumal, Seithikurippu R; Cardinali, Daniel P; Alzoghaibi, Mohammad

2017-01-01

We hypothesized that if we control for food composition, caloric intake, light exposure, sleep schedule, and exercise, intermittent fasting would not influence the circadian pattern of melatonin. Therefore, we designed this study to assess the effect of intermittent fasting on the circadian pattern of melatonin. Eight healthy volunteers with a mean age of 26.6 ± 4.9 years and body mass index of 23.7 ± 3.5 kg/m 2 reported to the Sleep Disorders Center (the laboratory) on four occasions: (1) adaptation, (2) 4 weeks before Ramadan while performing Islamic intermittent fasting for 1 week (fasting outside Ramadan [FOR]), (3) 1 week before Ramadan (nonfasting baseline [BL]), and (4) during the 2 nd week of Ramadan while fasting ( Ramadan ). The plasma levels of melatonin were measured using enzyme-linked immunoassays at 22:00, 02:00, 04:00, 06:00, and 11:00 h. The light exposure, meal composition, energy expenditure, and sleep schedules remained the same while the participants stayed at the laboratory. The melatonin levels followed the same circadian pattern during the three monitoring periods (BL, FOR, and Ramadan ). The peak melatonin level was at 02:00 h and the trough level was at 11:00 h in all studied periods. Lower melatonin levels at 22:00 h were found during fasting compared to BL. Cosinor analysis revealed no significant changes in the acrophase of melatonin levels. In this preliminary report, under controlled conditions of light exposure, meal composition, energy expenditure, and sleep-wake schedules, intermittent fasting has no significant influence on the circadian pattern of melatonin.

The influence of intermittent fasting on the circadian pattern of melatonin while controlling for caloric intake, energy expenditure, light exposure, and sleep schedules: A preliminary report

PubMed Central

Almeneessier, Aljohara S.; Bahammam, Ahmed S.; Sharif, Munir M.; Bahammam, Salman A.; Nashwan, Samar Z.; Pandi Perumal, Seithikurippu R.; Cardinali, Daniel P.; Alzoghaibi, Mohammad

2017-01-01

AIMS: We hypothesized that if we control for food composition, caloric intake, light exposure, sleep schedule, and exercise, intermittent fasting would not influence the circadian pattern of melatonin. Therefore, we designed this study to assess the effect of intermittent fasting on the circadian pattern of melatonin. METHODS: Eight healthy volunteers with a mean age of 26.6 ± 4.9 years and body mass index of 23.7 ± 3.5 kg/m2 reported to the Sleep Disorders Center (the laboratory) on four occasions: (1) adaptation, (2) 4 weeks before Ramadan while performing Islamic intermittent fasting for 1 week (fasting outside Ramadan [FOR]), (3) 1 week before Ramadan (nonfasting baseline [BL]), and (4) during the 2nd week of Ramadan while fasting (Ramadan). The plasma levels of melatonin were measured using enzyme-linked immunoassays at 22:00, 02:00, 04:00, 06:00, and 11:00 h. The light exposure, meal composition, energy expenditure, and sleep schedules remained the same while the participants stayed at the laboratory. RESULTS: The melatonin levels followed the same circadian pattern during the three monitoring periods (BL, FOR, and Ramadan). The peak melatonin level was at 02:00 h and the trough level was at 11:00 h in all studied periods. Lower melatonin levels at 22:00 h were found during fasting compared to BL. Cosinor analysis revealed no significant changes in the acrophase of melatonin levels. CONCLUSIONS: In this preliminary report, under controlled conditions of light exposure, meal composition, energy expenditure, and sleep-wake schedules, intermittent fasting has no significant influence on the circadian pattern of melatonin. PMID:28808490

Ultrafast optical pulse convertor caused by oscillations of the energy level structure in the conjugated polymer poly(p-phenylenevinylene).

PubMed

Zhang, Yusong; Chen, Weikang; Lin, Zhe; Li, Sheng; George, Thomas F

2017-08-21

For a conjugated polymer irradiated by two optical pulses, the whole process of excitation, involving lattice oscillations, oscillations of the energy level structure, and evolution of the electron cloud, is investigated. Localization of the electron cloud appears in the first 100 fs of irradiation, which in turn induces vibrations of lattice of the polymer chain as well as oscillations of the band gap. These oscillations filter the absorption of the external optical field inversely and convert the original optical field to an ultrafast light field whose intensity varies with a certain period. Based on the mechanism, oscillations of the energy level structure, induced by the external excitation, can be designed as an ultrafast response optical convertor that is able to change the external optical pulse into a new effective light field with a certain oscillation period. This helps provide new insight into designing nanostructures for polymeric optoelectronics.

Design and implementation of an audio indicator

NASA Astrophysics Data System (ADS)

Zheng, Shiyong; Li, Zhao; Li, Biqing

2017-04-01

This page proposed an audio indicator which designed by using C9014, LED by operational amplifier level indicator, the decimal count/distributor of CD4017. The experimental can control audibly neon and holiday lights through the signal. Input audio signal after C9014 composed of operational amplifier for power amplifier, the adjust potentiometer extraction amplification signal input voltage CD4017 distributors make its drive to count, then connect the LED display running situation of the circuit. This simple audio indicator just use only U1 and can produce two colors LED with the audio signal tandem come pursuit of the running effect, from LED display the running of the situation takes can understand the general audio signal. The variation in the audio and the frequency of the signal and the corresponding level size. In this light can achieve jump to change, slowly, atlas, lighting four forms, used in home, hotel, discos, theater, advertising and other fields, and a wide range of USES, rU1h life in a modern society.

Osmotic Stress-Induced Polyamine Accumulation in Cereal Leaves 1

PubMed Central

Flores, Hector E.; Galston, Arthur W.

1984-01-01

Arginine decarboxylase activity increases 2- to 3-fold in osmotically stressed oat leaves in both light and dark, but putrescine accumulation in the dark is only one-third to one-half of that in light-stressed leaves. If arginine or ornithine are supplied to dark-stressed leaves, putrescine rises to levels comparable to those obtained by incubation under light. Thus, precursor amino acid availability is limiting to the stress response. Amino acid levels change rapidly upon osmotic treatment; notably, glutamic acid decreases with a corresponding rise in glutamine. Difluoromethylarginine (0.01-0.1 millimolar), the enzyme-activated irreversible inhibitor of arginine decarboxylase, prevents the stress-induced putrescine rise, as well as the incorporation of label from [14C]arginine, with the expected accumulation of free arginine, but has no effect on the rest of the amino acid pool. The use of specific inhibitors such as α-difluoromethylarginine is suggested as probes for the physiological significance of stress responses by plant cells. PMID:16663552

Moonlight affects nocturnal Period2 transcript levels in the pineal gland of the reef fish Siganus guttatus.

PubMed

Sugama, Nozomi; Park, Ji-Gweon; Park, Yong-Ju; Takeuchi, Yuki; Kim, Se-Jae; Takemura, Akihiro

2008-09-01

The golden rabbitfish Siganus guttatus is a reef fish with a restricted lunar-synchronized spawning cycle. It is not known how the fish recognizes cues from the moon and exerts moon-related activities. In order to evaluate the perception and utilization of moonlight by the fish, the present study aimed to clone and characterize Period2 (Per2), a light-inducible clock gene in lower vertebrates, and to examine daily variations in rabbitfish Per2 (rfPer2) expression as well as the effect of light and moonlight on its expression in the pineal gland. The partially-cloned rfPer2 cDNA (2933 bp) was highly homologous (72%) to zebrafish Per2. The rfPer2 levels increased at ZT6 and decreased at ZT18 in the whole brain and several peripheral organs. The rfPer2 expression in the pineal gland exhibited a daily variation with an increase during daytime. Exposing the fish to light during nighttime resulted in a rapid increase of its expression in the pineal gland, while the level was decreased by intercepting light during daytime. Two hours after exposing the fish to moonlight at the full moon period, the rfPer2 expression was upregulated. These results suggest that rfPer2 is a light-inducible clock gene and that its expression is affected not only by daylight but also by moonlight. Since the rfPer2 expression level during the full moon period was higher than that during the new moon period, the monthly variation in the rfPer2 expression is likely to occur with the change in amplitude between the full and new moon periods.

Effects of long-term nutrient additions on Arctic tundra, stream, and lake ecosystems: beyond NPP.

PubMed

Gough, Laura; Bettez, Neil D; Slavik, Karie A; Bowden, William B; Giblin, Anne E; Kling, George W; Laundre, James A; Shaver, Gaius R

2016-11-01

Primary producers form the base of food webs but also affect other ecosystem characteristics, such as habitat structure, light availability, and microclimate. Here, we examine changes caused by 5-30+ years of nutrient addition and resulting increases in net primary productivity (NPP) in tundra, streams, and lakes in northern Alaska. The Arctic provides an important opportunity to examine how ecosystems characterized by low diversity and low productivity respond to release from nutrient limitation. We review how responses of algae and plants affect light availability, perennial biotic structures available for consumers, oxygen levels, and temperature. Sometimes, responses were similar across all three ecosystems; e.g., increased NPP significantly reduced light to the substrate following fertilization. Perennial biotic structures increased in tundra and streams but not in lakes, and provided important new habitat niches for consumers as well as other producers. Oxygen and temperature responses also differed. Life history traits (e.g., longevity) of the primary producers along with the fate of detritus drove the responses and recovery. As global change persists and nutrients become more available in the Arctic and elsewhere, incorporating these factors as response variables will enable better prediction of ecosystem changes and feedbacks in this biome and others.

Survey of the BY Draconis syndrome among dMe stars. [BVr photometry search for slow quasisinusoidal light variations

NASA Technical Reports Server (NTRS)

Bopp, B. W.; Espenak, F.

1977-01-01

Results are reported for a BVr photometric survey of 22 dK, dKe, dM, and dMe stars conducted to search for slow quasi-sinusoidal fluctuations in V (the BY Draconis syndrome). The (B-V) and (V-r) color indices are determined in an attempt to detect wavelength-dependent color changes produced by starspots and to infer starspot temperatures. It is found that nine of the stars exhibit variations in V of the order of 0.05 to 0.10 magnitude on a time scale of days or weeks, that at least three more display changes in mean light level over a period of years, that the stars generally tend to become redder at minimum light, and that some of the stars show no detectable color changes over their photometric cycle. The color data are taken to suggest a probable temperature difference of about 200 to 500 K between the stellar photospheres and starspots if the V variations are attributed to dark spots. It is concluded that the BY Draconis syndrome is clearly a very common occurrence among dMe stars.

Qubit-flip-induced cavity mode squeezing in the strong dispersive regime of the quantum Rabi model

PubMed Central

Joshi, Chaitanya; Irish, Elinor K.; Spiller, Timothy P.

2017-01-01

Squeezed states of light are a set of nonclassical states in which the quantum fluctuations of one quadrature component are reduced below the standard quantum limit. With less noise than the best stabilised laser sources, squeezed light is a key resource in the field of quantum technologies and has already improved sensing capabilities in areas ranging from gravitational wave detection to biomedical applications. In this work we propose a novel technique for generating squeezed states of a confined light field strongly coupled to a two-level system, or qubit, in the dispersive regime. Utilising the dispersive energy shift caused by the interaction, control of the qubit state produces a time-dependent change in the frequency of the light field. An appropriately timed sequence of sudden frequency changes reduces the quantum noise fluctuations in one quadrature of the field well below the standard quantum limit. The degree of squeezing and the time of generation are directly controlled by the number of frequency shifts applied. Even in the presence of realistic noise and imperfections, our protocol promises to be capable of generating a useful degree of squeezing with present experimental capabilities. PMID:28358025

Post DSAEK Optical Changes: A Comprehensive Prospective Analysis on the Role of Ocular Wavefront Aberrations, Haze, and Corneal Thickness

PubMed Central

Hindman, Holly B.; Huxlin, Krystel R.; Pantanelli, Seth M.; Callan, Christine L.; Sabesan, Ramkumar; Ching, Steven S.T.; Miller, Brooke E.; Martin, Tim; Yoon, Geunyoung

2014-01-01

Purpose To assess the visual impact of ocular wavefront aberrations, corneal thickness, and corneal light scatter prospectively after Descemet’s Stripping Automated Endothelial Keratoplasty (DSAEK) in humans. Methods Data were obtained prospectively from 20 eyes pre-operatively and at 1, 3, 6, and 12 months post- DSAEK. At each visit, best spectacle corrected visual acuity (BSCVA) and visual acuity with glare (Brightness Acuity Testing - BAT) were recorded and ocular wavefront measurements and corneal Optical Coherence Tomography (OCT) performed. Magnitude and sign of individual Zernike terms (higher order aberrations HOA) were determined. Epithelial, host stromal, donor stromal, and total corneal thickness were quantified. Brightness, intensity profiles of OCT images were generated to quantify light scatter in the whole cornea, subepithelial region, anterior and posterior host stroma, interface, and donor stroma. Results Mean BSCVA and glare disability at low light levels improved from 1 to 12 months post-DSAEK. All corneal thicknesses and ocular lower- and HOAs were stable from 1 through 12 months, whereas total corneal, host stromal, and interface brightness intensities decreased significantly over the same period. A repeated measures ANOVA across the follow up period found that the change in scatter, but not the change in higher order aberrations, could account for the variability occurring in acuity from 1 to 12 months post-DSAEK. Conclusions While ocular HOAs and scatter are both elevated over normal post-DSAEK, our results demonstrate that improvements in visual performance occurring over the first year post-DSAEK are associated with decreasing light scatter. In contrast, there were no significant changes in ocular HOAs during this time. Because corneal light scatter decreased between 1 and 12 months despite stable corneal thicknesses over the same period, we conclude that factors that induced light scatter, other than tissue thickness or swelling (corneal edema), significantly impacted the visual improvements that occurred over time post-DSAEK. A better understanding of the cellular and extracellular matrix changes of the subepithelial region and interface, incurred by the surgical creation of a lamellar host -graft interface, and the subsequent healing of these tissues, is warranted. PMID:24162748

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

NASA Astrophysics Data System (ADS)

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).

Limits of Spatial Attention in Three-Dimensional Space and Dual-task Driving Performance

PubMed Central

Andersen, George J.; Ni, Rui; Bian, Zheng; Kang, Julie

2010-01-01

The present study examined the limits of spatial attention while performing two driving relevant tasks that varied in depth. The first task was to maintain a fixed headway distance behind a lead vehicle that varied speed. The second task was to detect a light-change target in an array of lights located above the roadway. In Experiment 1 the light detection task required drivers to encode color and location. The results indicated that reaction time to detect a light-change target increased and accuracy decreased as a function of the horizontal location of the light-change target and as a function of the distance from the driver. In a second experiment the light change task was changed to a singleton search (detect the onset of a yellow light) and the workload of the car following task was systematically varied. The results of Experiment 2 indicated that RT increased as a function of task workload, the 2D position of the light-change target and the distance of the light-change target. A multiple regression analysis indicated that the effect of distance on light detection performance was not due to changes in the projected size of the light target. In Experiment 3 we found that the distance effect in detecting a light change could not be explained by the location of eye fixations. The results demonstrate that when drivers attend to a roadway scene attention is limited in three-dimensional space. These results have important implications for developing tests for assessing crash risk among drivers as well as the design of in vehicle technologies such as head-up displays. PMID:21094336

Treating presbyopia without spectacles

NASA Astrophysics Data System (ADS)

Xu, Renfeng

Both multifocal optics and small pupils can increase the depth of focus (DoF) of presbyopes. This thesis will evaluate some of the unique challenges faced by each of these two strategies. First, there is no single spherical refracting lens that can focus all parts of the pupil of an aberrated eye. What is the objective and subjective spherical refractive error (Rx) for such an eye, and does it vary with the amount of primary SA? Using both computational modeling and psychophysical methods, we found that high levels of positive Seidel SA caused both objective and subjective refractions to become myopic. Significantly, this refractive shift varied with stimulus spatial frequency and subjective criterion. Second, although secondary SA can dramatically expand DoF, we show that this is mostly due to the lower order components within this polynomial, which can also change spherical Rx. Also, the r6 term that defines secondary SA actually narrows rather than expands DoF, when in the presence of the r4 term within Z60. Finally, as retinal illuminance drops, neural thresholds are elevated due to increased problems of photon noise. We asked if the gains in near and distant vision of presbyopes anticipated at high light levels would be cancelled or even reversed at low light levels because of the additional reduction in retinal illuminance contributed by small pupils. We found that when light levels are > 2 cd/m2, a small pupil with a diameter of 2--3mm improves near image quality, near visual acuity, and near reading speed without significant loss of distance image quality and distance vision. This result gains added significance because we also showed that low light level text in the urban environment always has luminance levels > 2 cd/m2. In conclusion, both small pupils and multifocal optics face significant challenges as near vision aids for presbyopes. However, some of the confounding effects of elevated SA levels are avoided by using small pupils to expand DoF, which can provide improved near and distance vision at most light levels encountered while reading.

High light intensity mediates a shift from allochthonous to autochthonous carbon use in phototrophic stream biofilms

NASA Astrophysics Data System (ADS)

Wagner, Karoline; Bengtsson, Mia M.; Findlay, Robert H.; Battin, Tom J.; Ulseth, Amber J.

2017-07-01

Changes in the riparian vegetation along stream channels, diurnal light availability, and longitudinal fluctuations in the local light regime in streams influence primary production and carbon (C) cycling in benthic stream biofilms. To investigate the influence of light availability on the uptake dynamics of autochthonous and allochthonous dissolved organic carbon (DOC) in benthic biofilms, we experimentally added 13C-labeled allochthonous DOC to biofilms grown under light intensities ranging from 5 to 152 μmol photons m-2 s-1. We calculated the net C flux, which showed that benthic biofilms released autochthonous DOC across the entire light gradient. Light availability and diurnal light patterns influenced C uptake by benthic biofilms. More allochthonous DOC was respired under low light availability and at night, whereas under high light availability and during the day mainly autochthonous C was respired by the benthic biofilm community. Furthermore, phenol oxidase activity (indicative of allochthonous DOC uptake) was more elevated under low light availability, whereas beta-glucosidase activity (indicative of autochthonous DOC use) increased with light intensity. Collectively, our results suggest that biofilms exposed to high light inputs preferentially used autochthonous DOC, whereas biofilms incubated at attenuated levels showed greater use of allochthonous DOC. This has implications for the spatial dynamics of DOC uptake in streams and speaks against the occurrence of priming effects in algal-dominated stream biofilms.

Diurnal Regulation of Cellular Processes in the Cyanobacterium Synechocystis sp. Strain PCC 6803: Insights from Transcriptomic, Fluxomic, and Physiological Analyses

PubMed Central

Saha, Rajib; Liu, Deng; Hoynes-O’Connor, Allison; Liberton, Michelle; Yu, Jingjie; Bhattacharyya-Pakrasi, Maitrayee; Balassy, Andrea; Zhang, Fuzhong; Maranas, Costas D.

2016-01-01

ABSTRACT Synechocystis sp. strain PCC 6803 is the most widely studied model cyanobacterium, with a well-developed omics level knowledgebase. Like the lifestyles of other cyanobacteria, that of Synechocystis PCC 6803 is tuned to diurnal changes in light intensity. In this study, we analyzed the expression patterns of all of the genes of this cyanobacterium over two consecutive diurnal periods. Using stringent criteria, we determined that the transcript levels of nearly 40% of the genes in Synechocystis PCC 6803 show robust diurnal oscillating behavior, with a majority of the transcripts being upregulated during the early light period. Such transcripts corresponded to a wide array of cellular processes, such as light harvesting, photosynthetic light and dark reactions, and central carbon metabolism. In contrast, transcripts of membrane transporters for transition metals involved in the photosynthetic electron transport chain (e.g., iron, manganese, and copper) were significantly upregulated during the late dark period. Thus, the pattern of global gene expression led to the development of two distinct transcriptional networks of coregulated oscillatory genes. These networks help describe how Synechocystis PCC 6803 regulates its metabolism toward the end of the dark period in anticipation of efficient photosynthesis during the early light period. Furthermore, in silico flux prediction of important cellular processes and experimental measurements of cellular ATP, NADP(H), and glycogen levels showed how this diurnal behavior influences its metabolic characteristics. In particular, NADPH/NADP+ showed a strong correlation with the majority of the genes whose expression peaks in the light. We conclude that this ratio is a key endogenous determinant of the diurnal behavior of this cyanobacterium. PMID:27143387

Metabolic Architecture of the Cereal Grain and Its Relevance to Maximize Carbon Use Efficiency1[OPEN

PubMed Central

Rolletschek, Hardy; Grafahrend-Belau, Eva; Munz, Eberhard; Radchuk, Volodymyr; Kartäusch, Ralf; Tschiersch, Henning; Melkus, Gerd; Schreiber, Falk; Jakob, Peter M.; Borisjuk, Ljudmilla

2015-01-01

Here, we have characterized the spatial heterogeneity of the cereal grain’s metabolism and demonstrated how, by integrating a distinct set of metabolic strategies, the grain has evolved to become an almost perfect entity for carbon storage. In vivo imaging revealed light-induced cycles in assimilate supply toward the ear/grain of barley (Hordeum vulgare) and wheat (Triticum aestivum). In silico modeling predicted that, in the two grain storage organs (the endosperm and embryo), the light-induced shift in solute influx does cause adjustment in metabolic flux without changes in pathway utilization patterns. The enveloping, leaf-like pericarp, in contrast, shows major shifts in flux distribution (starch metabolism, photosynthesis, remobilization, and tricarboxylic acid cycle activity) allow to refix 79% of the CO2 released by the endosperm and embryo, allowing the grain to achieve an extraordinary high carbon conversion efficiency of 95%. Shading experiments demonstrated that ears are autonomously able to raise the influx of solutes in response to light, but with little effect on the steady-state levels of metabolites or transcripts or on the pattern of sugar distribution within the grain. The finding suggests the presence of a mechanism(s) able to ensure metabolic homeostasis in the face of short-term environmental fluctuation. The proposed multicomponent modeling approach is informative for predicting the metabolic effects of either an altered level of incident light or a momentary change in the supply of sucrose. It is therefore of potential value for assessing the impact of either breeding and/or biotechnological interventions aimed at increasing grain yield. PMID:26395842

Metabolic Architecture of the Cereal Grain and Its Relevance to Maximize Carbon Use Efficiency.

PubMed

Rolletschek, Hardy; Grafahrend-Belau, Eva; Munz, Eberhard; Radchuk, Volodymyr; Kartäusch, Ralf; Tschiersch, Henning; Melkus, Gerd; Schreiber, Falk; Jakob, Peter M; Borisjuk, Ljudmilla

2015-11-01

Here, we have characterized the spatial heterogeneity of the cereal grain's metabolism and demonstrated how, by integrating a distinct set of metabolic strategies, the grain has evolved to become an almost perfect entity for carbon storage. In vivo imaging revealed light-induced cycles in assimilate supply toward the ear/grain of barley (Hordeum vulgare) and wheat (Triticum aestivum). In silico modeling predicted that, in the two grain storage organs (the endosperm and embryo), the light-induced shift in solute influx does cause adjustment in metabolic flux without changes in pathway utilization patterns. The enveloping, leaf-like pericarp, in contrast, shows major shifts in flux distribution (starch metabolism, photosynthesis, remobilization, and tricarboxylic acid cycle activity) allow to refix 79% of the CO2 released by the endosperm and embryo, allowing the grain to achieve an extraordinary high carbon conversion efficiency of 95%. Shading experiments demonstrated that ears are autonomously able to raise the influx of solutes in response to light, but with little effect on the steady-state levels of metabolites or transcripts or on the pattern of sugar distribution within the grain. The finding suggests the presence of a mechanism(s) able to ensure metabolic homeostasis in the face of short-term environmental fluctuation. The proposed multicomponent modeling approach is informative for predicting the metabolic effects of either an altered level of incident light or a momentary change in the supply of sucrose. It is therefore of potential value for assessing the impact of either breeding and/or biotechnological interventions aimed at increasing grain yield. © 2015 American Society of Plant Biologists. All Rights Reserved.

Visible light alters yeast metabolic rhythms by inhibiting respiration.

PubMed

Robertson, James Brian; Davis, Chris R; Johnson, Carl Hirschie

2013-12-24

Exposure of cells to visible light in nature or in fluorescence microscopy often is considered to be relatively innocuous. However, using the yeast respiratory oscillation (YRO) as a sensitive measurement of metabolism, we find that non-UV visible light has a significant impact on yeast metabolism. Blue/green wavelengths of visible light shorten the period and dampen the amplitude of the YRO, which is an ultradian rhythm of cell metabolism and transcription. The wavelengths of light that have the greatest effect coincide with the peak absorption regions of cytochromes. Moreover, treating yeast with the electron transport inhibitor sodium azide has similar effects on the YRO as visible light. Because impairment of respiration by light would change several state variables believed to play vital roles in the YRO (e.g., oxygen tension and ATP levels), we tested oxygen's role in YRO stability and found that externally induced oxygen depletion can reset the phase of the oscillation, demonstrating that respiratory capacity plays a role in the oscillation's period and phase. Light-induced damage to the cytochromes also produces reactive oxygen species that up-regulate the oxidative stress response gene TRX2 that is involved in pathways that enable sustained growth in bright visible light. Therefore, visible light can modulate cellular rhythmicity and metabolism through unexpectedly photosensitive pathways.

Comparison of Depth of Cure, Hardness and Heat Generation of LED and High Intensity QTH Light Sources.

PubMed

Mousavinasab, Sayed Mostafa; Meyers, Ian

2011-07-01

To compare curing performance of a second generation LED curing light with a high power tungsten quartz halogen (QTH). A hybrid composite resin (Filtek Z 250, 3M, USA) was used as test material and cured using a second generation LED light (Translux Power Blue™, Heraus Kulzer ,Germany) or a very high power QTH light unit (EMS, Switzerland). A two split aluminum mold was used to prepare ten samples with LED light source cured for forty seconds and ten samples prepared using high power QTH light unit, cured for four or six seconds recommended exposure time. Hardness, depth of cure (DOC) and thermal rise during exposure time by these light sources were measured. The data submitted to analysis of variance (ANOVA), Tukey's and student's t tests at 5% significance level. Significant differences were found in hardness, DOC of samples cured by above mentioned light sources and also in thermal rises during exposure time. The curing performance of the tested QTH was not as well as the LED light. TPB light source produced the maximum hardness (81.25, 73.29, 65.49,55.83 and 24.53 for 0 mm, 1 mm, 2 mm, 3 mm and 4 mm intervals) and DOC (2.64 mm) values with forty seconds irradiation time and the high power (QTH) the least hardness (73.27, 61.51 and 31.59 for 0 mm, 1 mm and 2 mm, respectively) and DOC (2 mm) values with four seconds irradiation time. Thermal rises during 4 s and 6 s curing time using high power QTH and tested LED were 1.88°C, 3°C and 1.87°C, respectively. The used high power LED light produced greater hardness and depth of cure during forty seconds exposure time compared to high power QTH light with four or six seconds curing time. Thermal rise during 6 s curing time with QTH was greater compared to thermal changes occurred during 40 s curing time with tested LED light source. There was no difference seen in thermal changes caused by LED light with 40 s and QTH light with 4 s exposure time.

LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Selective reflection of obliquely incident polarised light

NASA Astrophysics Data System (ADS)

Fofanov, Ya A.

2009-06-01

A series of reflection resonances formed by the hyperfine components of the D2-lines in the spectrum of the natural mixture of rubidium isotopes is studied. Passages from resonantly frustrated total internal reflection to resonance Brewster reflection caused by the frequency tuning of the incident light are demonstrated experimentally. The contrast of the strongest refection resonances exceeds 500% at the moderate heating of reflecting cells. The intensity of the reflected light changes in this case by more than 20 times. A theory is developed which is based on a two-level model for resonance atoms and Fresnel formulas for reflection coefficients. Numerical calculations based on the proposed theory confirm main experimental results.

In Vivo Single-Cell Fluorescence and Size Scaling of Phytoplankton Chlorophyll Content.

PubMed

Álvarez, Eva; Nogueira, Enrique; López-Urrutia, Ángel

2017-04-01

In unicellular phytoplankton, the size scaling exponent of chlorophyll content per cell decreases with increasing light limitation. Empirical studies have explored this allometry by combining data from several species, using average values of pigment content and cell size for each species. The resulting allometry thus includes phylogenetic and size scaling effects. The possibility of measuring single-cell fluorescence with imaging-in-flow cytometry devices allows the study of the size scaling of chlorophyll content at both the inter- and intraspecific levels. In this work, the changing allometry of chlorophyll content was estimated for the first time for single phytoplankton populations by using data from a series of incubations with monocultures exposed to different light levels. Interspecifically, our experiments confirm previous modeling and experimental results of increasing size scaling exponents with increasing irradiance. A similar pattern was observed intraspecifically but with a larger variability in size scaling exponents. Our results show that size-based processes and geometrical approaches explain variations in chlorophyll content. We also show that the single-cell fluorescence measurements provided by imaging-in-flow devices can be applied to field samples to understand the changes in the size dependence of chlorophyll content in response to environmental variables affecting primary production. IMPORTANCE The chlorophyll concentrations in phytoplankton register physiological adjustments in cellular pigmentation arising mainly from changes in light conditions. The extent of these adjustments is constrained by the size of the phytoplankton cells, even within single populations. Hence, variations in community chlorophyll derived from photoacclimation are also dependent on the phytoplankton size distribution. Copyright © 2017 American Society for Microbiology.

In Vivo Single-Cell Fluorescence and Size Scaling of Phytoplankton Chlorophyll Content

PubMed Central

Nogueira, Enrique; López-Urrutia, Ángel

2017-01-01

ABSTRACT In unicellular phytoplankton, the size scaling exponent of chlorophyll content per cell decreases with increasing light limitation. Empirical studies have explored this allometry by combining data from several species, using average values of pigment content and cell size for each species. The resulting allometry thus includes phylogenetic and size scaling effects. The possibility of measuring single-cell fluorescence with imaging-in-flow cytometry devices allows the study of the size scaling of chlorophyll content at both the inter- and intraspecific levels. In this work, the changing allometry of chlorophyll content was estimated for the first time for single phytoplankton populations by using data from a series of incubations with monocultures exposed to different light levels. Interspecifically, our experiments confirm previous modeling and experimental results of increasing size scaling exponents with increasing irradiance. A similar pattern was observed intraspecifically but with a larger variability in size scaling exponents. Our results show that size-based processes and geometrical approaches explain variations in chlorophyll content. We also show that the single-cell fluorescence measurements provided by imaging-in-flow devices can be applied to field samples to understand the changes in the size dependence of chlorophyll content in response to environmental variables affecting primary production. IMPORTANCE The chlorophyll concentrations in phytoplankton register physiological adjustments in cellular pigmentation arising mainly from changes in light conditions. The extent of these adjustments is constrained by the size of the phytoplankton cells, even within single populations. Hence, variations in community chlorophyll derived from photoacclimation are also dependent on the phytoplankton size distribution. PMID:28115378

Vitamin D2 from light-exposed edible mushrooms is safe, bioavailable and effectively supports bone growth in rats.

PubMed

Calvo, M S; Babu, U S; Garthoff, L H; Woods, T O; Dreher, M; Hill, G; Nagaraja, S

2013-01-01

Widespread poor vitamin D status, a health risk for bone disease, increases the need for new food sources of vitamin D. Light-exposed edible mushrooms synthesize vitamin D(2). Bioavailability, safety, and efficacy of high levels of vitamin D(2) from mushrooms to support bone health was established in chronically fed growing rats. Poor vitamin D status from reduced sun exposure is made worse by limited access to vitamin D-containing foods. Exposing white button mushrooms to ultraviolet B (UVB) light markedly increases their vitamin D(2) content, creating a new food source of vitamin D. We used a growing rat model to determine safety, bioavailability, and efficacy in support of bone growth by vitamin D(2) from UVB-exposed mushrooms. We fed 150 weanling female rats one of five diets for 10 weeks, all formulated on AIN-93 G. Control diets contained no mushrooms either with or without vitamin D(3). Other diets contained 2.5% and 5.0% of UVB-exposed or -unexposed mushrooms. Safety of the high levels of vitamin D(2) from mushrooms was assessed by animal growth and by Von Kossa staining for soft tissue calcification. Bioavailability was determined from changes in circulating levels of 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH). Efficacy in support of bone growth was determined from measures of femur bending properties, size, mineralization, and microarchitecture. Diets containing 2.5% and 5.0% light-exposed mushrooms significantly raised 25(OH)D and suppressed PTH levels compared to control-fed rats or rats fed 5.0% mushroom unexposed to light. Microarchitecture and trabecular mineralization were only modestly higher in the light-treated mushroom-fed rats compared to the controls. Von Kossa staining revealed no soft tissue calcification despite very high plasma 25(OH)D. Vitamin D(2) from UVB-exposed mushrooms is bioavailable, safe, and functional in supporting bone growth and mineralization in a growing rat model without evidence of toxicity.

Chronic unpredictable mild stress-induced depressive-like behavior and dysregulation of brain levels of biogenic amines in Drosophila melanogaster.

PubMed

Araujo, Stífani Machado; Poetini, Marcia Rósula; Bortolotto, Vandreza Cardoso; de Freitas Couto, Shanda; Pinheiro, Franciane Cabral; Meichtry, Luana Barreto; de Almeida, Francielli Polet; Santos Musachio, Elize Aparecida; de Paula, Mariane Trindade; Prigol, Marina

2018-05-24

The etiopathogenesis of depression may involve repeated exposure to several unpredictable stressors. This study was conducted to investigate changes induced by chronic unpredictable mild stress (CUMS) and to assess behavioral and neurochemical changes that predict depressive-like behavior in Drosophila melanogaster. Male Drosophila melanogaster flies were exposed to CUMS with several stressors (cold, heat, starvation, and sleep deprivation) in an unpredictable and chronic manner for ten days. At the end of treatment, in vivo behavioral tests (open field, aggression, forced swimming, mating, light/dark box, male fertility evaluation, sucrose preference, weight evaluation) and ex vivo analyses (dopamine and serotonin levels) were performed. Using this CUMS model, we obtained results that contribute to the construction of a depressive model in Drosophila, where we reproduce some behavioral phenotypes corresponding to depressive symptoms, such as immobility in the forced swimming test, less exploration in the light/dark test, changes in mating behavior, changes in the aggressiveness test, reduced sucrose preference, and weight-loss, in addition to a significant reduction in the levels of serotonin and dopamine when compared to the control group. Fluoxetine was used in our study as a positive control to demonstrate that CUMS-induced depressive-like behaviors in flies can be reversed by antidepressants. In conclusion, male Drosophila melanogaster exposed to CUMS display a depressive-like phenotype, and, while this poses some limitations as an animal model for depression, it meets some of the criteria required to be a valid model, such as good face and construct validity. Copyright © 2018. Published by Elsevier B.V.

The effect of 580 nm-based-LED mixed light on growth, adipose deposition, skeletal development, and body temperature of chickens.

PubMed

Yang, Yefeng; Zhen, Chenghuang; Yang, Bo; Yu, Yonghua; Pan, Jinming

2018-06-01

Though previous study indicated that the 580 nm-yellow-LED-light showed an stimulating effect on growth of chickens, the low luminous efficiency of the yellow LED light cannot reflect the advantage of energy saving. In present study, the cool white LED chips and yellow LED chips have been combined to fabricate the white × yellow mixed LED light, with an enhanced luminous efficiency. A total 300 newly hatched chickens were reared under various mixed LED light. The results indicated that the white × yellow mixed LED light had "double-edged sword" effects on bird's body weight, bone development, adipose deposition, and body temperature, depending on variations in ratios of yellow component. Low yellow ratio of mixed LED light (Low group) inhibited body weight, whereas medium and high yellow ratio of mixed LED light (Medium and High groups) promoted body weight, compared with white LED light (White group). A progressive change in yellow component gave rise to consistent changes in body weight over the entire experiment. Moreover, a positive relationship was observed between yellow component and feed conversion ratio. High group-treated birds had greater relative abdominal adipose weight than Medium group-treated birds (P = 0.048), whereas Medium group-treated birds had greater relative abdominal adipose weight than Low group-treated birds (P = 0.044). We found that mixed light improved body weight by enhancing skeletal development (R 2  = 0.5023, P = 0.0001) and adipose deposition (R 2  = 0.6012, P = 0.0001). Birds in the Medium, High and Yellow groups attained significantly higher surface temperatures compared with the White group (P = 0.010). The results suggest that the application of the mixed light with high level of yellow component can be used successfully to improve growth and productive performance in broilers. Copyright © 2018. Published by Elsevier B.V.

Change in neighborhood disadvantage and change in smoking behaviors in adults: a longitudinal, within-individual study

PubMed Central

Halonen, Jaana I; Pulakka, Anna; Stenholm, Sari; Pentti, Jaana; Kawachi, Ichiro; Kivimäki, Mika; Vahtera, Jussi

2017-01-01

Background Evidence for an association between neighborhood disadvantage and smoking is mixed and mainly based on cross-sectional studies. To shed light on the causality of this association we examined whether change in neighborhood socioeconomic disadvantage is associated with within-individual change in smoking behaviors. Methods The study population comprised participants of the Finnish Public Sector study who reported a change in their smoking behavior between surveys in 2008/09 and 2012/13. We linked participants’ residential addresses to a total population database on neighborhood disadvantage with 250×250m resolution. The outcome variables were changes in smoking status (being a smoker vs. not) as well as the intensity (heavy/moderate vs. light smoker). We used longitudinal case-crossover design, a method that accounts for time-invariant confounders by design. We adjusted models for time-varying covariates. Results Of the 3443 participants, 1714 quit while 967 began to smoke between surveys. Smoking intensity increased among 398 and decreased among 364 participants. The level of neighborhood disadvantage changed for 1078 participants because they moved residence. Increased disadvantage was associated with increased odds of being a smoker (odds ratio (OR) of taking up smoking 1.23 (95% CI 1.04-1.47) per 1 standard deviation (SD) increase in standardized national disadvantage score). OR for being a heavy/moderate (vs. light) smoker was 1.14 (95% CI 0.85-1.52) when disadvantage increased by 1 SD. Conclusions These within-individual results link an increase in neighborhood socioeconomic disadvantage, due to move in residence, with subsequent smoking behaviors. PMID:27337178

Pilot study on laser propagation in maxillary and mandibular bone: Grey level image analysis for optical measurements.

PubMed

Guiselini, Monalisa Jacob; Deana, Alessandro Melo; de Fátima Teixeira da Silva, Daniela; Koshoji, Nelson Hideyoshi; Mesquita-Ferrari, Raquel Agnelli; do Vale, Katia Llanos; Mascaro, Marcelo Betti; de Moraes, Simone Aleksandra; Bussadori, Sandra Kalil; Fernandes, Kristianne Porta Santos

2017-06-01

Bone tissue anatomy, density and porosity vary among subjects in different phases of life and even within areas of a single specimen. The optical characteristics of changes in bone tissue are analyzed based on these properties. Photobiomodulation has been used to improve bone healing after surgery or fractures. Thus, knowledge on light propagation is of considerable importance to the obtainment of successful clinical outcomes. This study determines light penetration and distribution in human maxillary and mandibular bones in three different regions (anterior, middle, and posterior). A HeNe laser (633nm) irradiated maxillary and mandibular bones in the cervical-apical direction. The light propagation and scattering pattern were acquired and the grey level of the images was analyzed. Three-dimensional plots of the intensity profile and attenuation profiles were created. Differences in optical properties were found between the mandibular and maxillary bones. The maxilla attenuated more light than the mandible at all sites, leading to a shallower penetration depth. Our results provide initial information on the behavior of the propagation of red laser on alveolar bone using an optical method. Copyright © 2017 Elsevier B.V. All rights reserved.

Phonon-Mediated Exciton Stark Effect Enhanced by a Static Electric Field

NASA Astrophysics Data System (ADS)

Ivanov, A. L.

1997-03-01

The optical properties of semiconductor QW's change in the presence of coherent pump light. The exciton (phonon-mediated, biexciton-mediated, etc.) optical Stark effect is an effective shift of the exciton level that follow dynamically the intensity I0 ~= 0.1 div 1 GW/cm^2 of the pump light. In the present work we develop a theory of a low-intensity electric-field enhanced phonon-mediated optical Stark effect in polar semiconductors and semiconductor microstructures. The main point is that the exciton - LO-phonon Fröhlich interaction can be strongly enhanced by a (quasi-) static electric field F which polarizes the exciton in the geometry F | k | p, where k and p are the wavevectors of the pump and probe light, respectively. The electric field enhancement of spontaneous Raman scattering has been already analyzed (E. Burstein et al., 1971). Even a moderate electric field F ~= 10^3 V/cm reduces the intensity of the pump light to I0 ~= 1 div 10 MW/cm^2. Moreover, the phonon-mediated Stark effect enhanced by a static electric field F allow us to realize the both red and blue dynamical shifts of the exciton level.

Quality and noise measurements in mobile phone video capture

NASA Astrophysics Data System (ADS)

Petrescu, Doina; Pincenti, John

2011-02-01

The quality of videos captured with mobile phones has become increasingly important particularly since resolutions and formats have reached a level that rivals the capabilities available in the digital camcorder market, and since many mobile phones now allow direct playback on large HDTVs. The video quality is determined by the combined quality of the individual parts of the imaging system including the image sensor, the digital color processing, and the video compression, each of which has been studied independently. In this work, we study the combined effect of these elements on the overall video quality. We do this by evaluating the capture under various lighting, color processing, and video compression conditions. First, we measure full reference quality metrics between encoder input and the reconstructed sequence, where the encoder input changes with light and color processing modifications. Second, we introduce a system model which includes all elements that affect video quality, including a low light additive noise model, ISP color processing, as well as the video encoder. Our experiments show that in low light conditions and for certain choices of color processing the system level visual quality may not improve when the encoder becomes more capable or the compression ratio is reduced.

A multicentre phase III randomised controlled single-masked clinical trial evaluating the clinical efficacy and safety of light-masks at preventing dark-adaptation in the treatment of early diabetic macular oedema (CLEOPATRA): study protocol for a randomised controlled trial.

PubMed

Sivaprasad, Sobha; Arden, Geoffrey; Prevost, A Toby; Crosby-Nwaobi, Roxanne; Holmes, Helen; Kelly, Joanna; Murphy, Caroline; Rubin, Gary; Vasconcelos, Joanna; Hykin, Philip

2014-11-22

This study will evaluate hypoxia, as a novel concept in the pathogenesis of diabetic macular oedema (DMO). As the oxygen demand of the eye is maximum during dark-adaptation, we hypothesize that wearing light-masks during sleep will cause regression and prevent the development and progression of DMO. The study protocol comprises both an efficacy and mechanistic evaluation to test this hypothesis. This is a phase III randomised controlled single-masked multicentre clinical trial to test the clinical efficacy of light-masks at preventing dark-adaptation in the treatment of non-central DMO. Three hundred patients with non-centre-involving DMO in at least one eye will be randomised 1:1 to light-masks and control masks (with no light) to be used during sleep at night for a period of 24 months. The primary outcome is regression of non-central oedema by assessing change in the zone of maximal retinal thickness at baseline on optical coherence tomography (SD-OCT). Secondary outcomes will evaluate the prevention of development and progression of DMO by assessing changes in retinal thickness in different regions of the macula, macular volume, refracted visual acuity and level of retinopathy. Safety parameters will include sleep disturbance. Adverse events and measures of compliance will be assessed over 24 months. Participants recruited to the mechanistic sub-study will have additional retinal oximetry, multifocal electroretinography (ERG) and microperimetry to evaluate the role of hypoxia by assessing and comparing changes induced by supplemental oxygen and the light-masks at 12 months. The outcomes of this study will provide insight into the pathogenesis of DMO and provide evidence on whether a simple, non-invasive device in the form of a light-mask can help prevent the progression to centre-involving DMO and visual impairment in people with diabetes.

Historic water-level changes and pumpage from the principal aquifers of the Memphis area, Tennessee: 1886-1975

USGS Publications Warehouse

Criner, James H.; Parks, William Scott

1976-01-01

Pumpage from the Fort Pillow Sand ("1,400-foot" sand) began in 1924 and increased at a yearly rate of about 0.6 Mgal/d (2.3 Ml/d) until 1942. From 1943 to 1962, pumpage averaged about 11.5 Mgal/d (43.5 Ml/d), then was reduced as MLGW (Memphis Light, Gas and Water Division) discontinued wells that became unserviceable. MLGW ceased pumping from the aquifer in 1974, and pumpage from the remaining industrial wells in Shelby County in 1975 was 4.4 Mgal/d (16.6 Ml/d). Water levels in the Fort Pillow Sand generally have risen since 1963. Water l evels in the aquifers in the Memphis area fluctuate inversely with changes in pumping. Analysis of observation-well and pumpage data indicates that local water levels can be altered by changing the pumping rates or by varying the areal distribution of pumping.

Microalgae population dynamics growth with AnMBR effluent: effect of light and phosphorus concentration.

PubMed

Sanchis-Perucho, P; Duran, F; Barat, R; Pachés, M; Aguado, D

2018-06-01

The aim of this study was to evaluate the effect of light intensity and phosphorus concentration on biomass growth and nutrient removal in a microalgae culture and their effect on their competition. The photobioreactor was continuously fed with the effluent from an anaerobic membrane bioreactor pilot plant treating real wastewater. Four experimental periods were carried out at different light intensities (36 and 52 μmol s -1 m -2 ) and phosphorus concentrations (around 6 and 15 mgP L -1 ). Four green algae - Scenedesmus, Chlorella, Monoraphidium and Chlamydomonas- and cyanobacterium were detected and quantified along whole experimental period. Chlorella was the dominant species when light intensity was at the lower level tested, and was competitively displaced by a mixed culture of Scenedesmus and Monoraphidium when light was increased. When phosphorus concentration in the photobioreactor was raised up to 15 mgP L -1 , a growth of cyanobacterium became the dominant species in the culture. The highest nutrient removal efficiency (around 58.4 ± 15.8% and 96.1 ± 16.5% of nitrogen and phosphorus, respectively) was achieved at 52 μmol s -1 m -2 of light intensity and 6.02 mgP L -1 of phosphorus concentration, reaching about 674 ± 86 mg L -1 of volatile suspended solids. The results obtained reveal how the light intensity supplied and the phosphorus concentration available are relevant operational factors that determine the microalgae species that is able to predominate in a culture. Moreover, changes in microalgae predominance can be induced by changes in the growth medium produced by the own predominant species.

Shear bond strength of orthodontic color-change adhesives with different light-curing times

PubMed Central

Bayani, Shahin; Ghassemi, Amirreza; Manafi, Safa; Delavarian, Mohadeseh

2015-01-01

Background: The purpose of this study was to evaluate the effect of light-curing time on the shear bond strength (SBS) of two orthodontic color-change adhesives (CCAs). Materials and Methods: A total of 72 extracted premolars were randomly assigned into 6 groups of 12 teeth each. Subsequent to primer application, a metal bracket was bonded to the buccal surface using an orthodontic adhesive. Two CCAs (Greengloo and Transbond Plus) were tested and one conventional light-cured adhesive (Resilience) served as control. For each adhesive, the specimens were light-cured for two different times of 20 and 40 s. All the specimens underwent mechanical testing using a universal testing machine to measure the SBS. Adhesive remnant index (ARI) was used to assess the remnant adhesive material on the tooth surface. All statistical analyses were performed using SPSS software. The significance level for all statistical tests was set at P ≤ 0.05. Results: The SBSs of the tested groups were in the range of 14.05-31.25 MPa. Greengloo adhesive showed the highest SBS values when light-cured for 40 s, and Transbond Plus adhesive showed the lowest values when light-cured for 20 s. ARI scores of Transbond Plus adhesive were significantly higher than those of controls, while other differences in ARI values were not significant. Conclusion: Within the limitations of his study, decreasing the light-curing time from 40 to 20 s decreased the SBS of the tested adhesives; however, this decline in SBS was statistically significant only in Transbond Plus adhesive PMID:26005468

Expression and testing in plants of ArcLight, a genetically-encoded voltage indicator used in neuroscience research.

PubMed

Matzke, Antonius J M; Matzke, Marjori

2015-10-12

It is increasingly appreciated that electrical controls acting at the cellular and supra-cellular levels influence development and initiate rapid responses to environmental cues. An emerging method for non-invasive optical imaging of electrical activity at cell membranes uses genetically-encoded voltage indicators (GEVIs). Developed by neuroscientists to chart neuronal circuits in animals, GEVIs comprise a fluorescent protein that is fused to a voltage-sensing domain. One well-known GEVI, ArcLight, undergoes strong shifts in fluorescence intensity in response to voltage changes in mammalian cells. ArcLight consists of super-ecliptic (SE) pHluorin (pH-sensitive fluorescent protein) with an A227D substitution, which confers voltage sensitivity in neurons, fused to the voltage-sensing domain of the voltage-sensing phosphatase of C iona i ntestinalis (Ci-VSD). In an ongoing effort to adapt tools of optical electrophysiology for plants, we describe here the expression and testing of ArcLight and various derivatives in different membranes of root cells in Arabidopsis thaliana. Transgenic constructs were designed to express ArcLight and various derivatives targeted to the plasma membrane and nuclear membranes of Arabidopsis root cells. In transgenic seedlings, changes in fluorescence intensity of these reporter proteins following extracellular ATP (eATP) application were monitored using a fluorescence microscope equipped with a high speed camera. Coordinate reductions in fluorescence intensity of ArcLight and Ci-VSD-containing derivatives were observed at both the plasma membrane and nuclear membranes following eATP treatments. However, similar responses were observed for derivatives lacking the Ci-VSD. The dispensability of the Ci-VSD suggests that in plants, where H(+) ions contribute substantially to electrical activities, the voltage-sensing ability of ArcLight is subordinate to the pH sensitivity of its SEpHluorin base. The transient reduction of ArcLight fluorescence triggered by eATP most likely reflects changes in pH and not membrane voltage. The pH sensitivity of ArcLight precludes its use as a direct sensor of membrane voltage in plants. Nevertheless, ArcLight and derivatives situated in the plasma membrane and nuclear membranes may offer robust, fluorescence intensity-based pH indicators for monitoring concurrent changes in pH at these discrete membrane systems. Such tools will assist analyses of pH as a signal and/or messenger at the cell surface and the nuclear periphery in living plants.

Mars 520-d mission simulation reveals protracted crew hypokinesis and alterations of sleep duration and timing.

PubMed

Basner, Mathias; Dinges, David F; Mollicone, Daniel; Ecker, Adrian; Jones, Christopher W; Hyder, Eric C; Di Antonio, Adrian; Savelev, Igor; Kan, Kevin; Goel, Namni; Morukov, Boris V; Sutton, Jeffrey P

2013-02-12

The success of interplanetary human spaceflight will depend on many factors, including the behavioral activity levels, sleep, and circadian timing of crews exposed to prolonged microgravity and confinement. To address the effects of the latter, we used a high-fidelity ground simulation of a Mars mission to objectively track sleep-wake dynamics in a multinational crew of six during 520 d of confined isolation. Measurements included continuous recordings of wrist actigraphy and light exposure (4.396 million min) and weekly computer-based neurobehavioral assessments (n = 888) to identify changes in the crew's activity levels, sleep quantity and quality, sleep-wake periodicity, vigilance performance, and workload throughout the record-long 17 mo of mission confinement. Actigraphy revealed that crew sedentariness increased across the mission as evident in decreased waking movement (i.e., hypokinesis) and increased sleep and rest times. Light exposure decreased during the mission. The majority of crewmembers also experienced one or more disturbances of sleep quality, vigilance deficits, or altered sleep-wake periodicity and timing, suggesting inadequate circadian entrainment. The results point to the need to identify markers of differential vulnerability to hypokinesis and sleep-wake changes during the prolonged isolation of exploration spaceflight and the need to ensure maintenance of circadian entrainment, sleep quantity and quality, and optimal activity levels during exploration missions. Therefore, successful adaptation to such missions will require crew to transit in spacecraft and live in surface habitats that instantiate aspects of Earth's geophysical signals (appropriately timed light exposure, food intake, exercise) required for temporal organization and maintenance of human behavior.

Lunar Phase Modulates Circadian Gene Expression Cycles in the Broadcast Spawning Coral Acropora millepora.

PubMed

Brady, Aisling K; Willis, Bette L; Harder, Lawrence D; Vize, Peter D

2016-04-01

Many broadcast spawning corals in multiple reef regions release their gametes with incredible temporal precision just once per year, using the lunar cycle to set the night of spawning. Moonlight, rather than tides or other lunar-regulated processes, is thought to be the proximate factor responsible for linking the night of spawning to the phase of the Moon. We compared patterns of gene expression among colonies of the broadcast spawning coral Acropora millepora at different phases of the lunar cycle, and when they were maintained under one of three experimentally simulated lunar lighting treatments: i) lunar lighting conditions matching those on the reef, or lunar patterns mimicking either ii) constant full Moon conditions, or iii) constant new Moon conditions. Normal lunar illumination was found to shift both the level and timing of clock gene transcription cycles between new and full moons, with the peak hour of expression for a number of genes occurring earlier in the evening under a new Moon when compared to a full Moon. When the normal lunar cycle is replaced with nighttime patterns equivalent to either a full Moon or a new Moon every evening, the normal monthlong changes in the level of expression are destroyed for most genes. In combination, these results indicate that daily changes in moonlight that occur over the lunar cycle are essential for maintaining normal lunar periodicity of clock gene transcription, and this may play a role in regulating spawn timing. These data also show that low levels of light pollution may have an impact on coral biological clocks. © 2016 Marine Biological Laboratory.

Pulsed ultraviolet light reduces immunoglobulin E binding to Atlantic white shrimp (Litopenaeus setiferus) extract.

PubMed

Shriver, Sandra; Yang, Wade; Chung, Si-Yin; Percival, Susan

2011-07-01

Pulsed ultraviolet light (PUV), a novel food processing and preservation technology, has been shown to reduce allergen levels in peanut and soybean samples. In this study, the efficacy of using PUV to reduce the reactivity of the major shrimp allergen, tropomyosin (36-kDa), and to attenuate immunoglobulin E (IgE) binding to shrimp extract was examined. Atlantic white shrimp (Litopenaeus setiferus) extract was treated with PUV (3 pulses/s, 10 cm from light source) for 4 min. Tropomyosin was compared in the untreated, boiled, PUV-treated and [boiled+PUV]-treated samples, and changes in the tropomyosin levels were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). IgE binding of the treated extract was analyzed via immunoblot and enzyme-linked immunosorbent assay (ELISA) using pooled human plasma containing IgE antibodies against shrimp allergens. Results showed that levels of tropomyosin and IgE binding were reduced following PUV treatment. However, boiling increased IgE binding, while PUV treatment could offset the increased allergen reactivity caused by boiling. In conclusion, PUV treatment reduced the reactivity of the major shrimp allergen, tropomyosin, and decreased the IgE binding capacity of the shrimp extract.

Circadian rhythmicity and light sensitivity of the zebrafish brain.

PubMed

Moore, Helen A; Whitmore, David

2014-01-01

Traditionally, circadian clocks have been thought of as a neurobiological phenomenon. This view changed somewhat over recent years with the discovery of peripheral tissue circadian oscillators. In mammals, however, the suprachiasmatic nucleus (SCN) in the hypothalamus still retains the critical role of a central synchronizer of biological timing. Zebrafish, in contrast, have always reflected a more highly decentralized level of clock organization, as individual cells and tissues contain directly light responsive circadian pacemakers. As a consequence, clock function in the zebrafish brain has remained largely unexplored, and the precise organization of rhythmic and light-sensitive neurons within the brain is unknown. To address this issue, we used the period3 (per3)-luciferase transgenic zebrafish to confirm that multiple brain regions contain endogenous circadian oscillators that are directly light responsive. In addition, in situ hybridization revealed localised neural expression of several rhythmic and light responsive clock genes, including per3, cryptochrome1a (cry1a) and per2. Adult brain nuclei showing significant clock gene expression include the teleost equivalent of the SCN, as well as numerous hypothalamic nuclei, the periventricular grey zone (PGZ) of the optic tectum, and granular cells of the rhombencephalon. To further investigate the light sensitive properties of neurons, expression of c-fos, a marker for neuronal activity, was examined. c-fos mRNA was upregulated in response to changing light conditions in different nuclei within the zebrafish brain. Furthermore, under constant dark (DD) conditions, c-fos shows a significant circadian oscillation. Taken together, these results show that there are numerous areas of the zebrafish central nervous system, which contain deep brain photoreceptors and directly light-entrainable circadian pacemakers. However, there are also multiple brain nuclei, which possess neither, demonstrating a degree of pacemaker complexity that was not previously appreciated.

Circadian Rhythmicity and Light Sensitivity of the Zebrafish Brain

PubMed Central

Moore, Helen A.; Whitmore, David

2014-01-01

Traditionally, circadian clocks have been thought of as a neurobiological phenomenon. This view changed somewhat over recent years with the discovery of peripheral tissue circadian oscillators. In mammals, however, the suprachiasmatic nucleus (SCN) in the hypothalamus still retains the critical role of a central synchronizer of biological timing. Zebrafish, in contrast, have always reflected a more highly decentralized level of clock organization, as individual cells and tissues contain directly light responsive circadian pacemakers. As a consequence, clock function in the zebrafish brain has remained largely unexplored, and the precise organization of rhythmic and light-sensitive neurons within the brain is unknown. To address this issue, we used the period3 (per3)-luciferase transgenic zebrafish to confirm that multiple brain regions contain endogenous circadian oscillators that are directly light responsive. In addition, in situ hybridization revealed localised neural expression of several rhythmic and light responsive clock genes, including per3, cryptochrome1a (cry1a) and per2. Adult brain nuclei showing significant clock gene expression include the teleost equivalent of the SCN, as well as numerous hypothalamic nuclei, the periventricular grey zone (PGZ) of the optic tectum, and granular cells of the rhombencephalon. To further investigate the light sensitive properties of neurons, expression of c-fos, a marker for neuronal activity, was examined. c-fos mRNA was upregulated in response to changing light conditions in different nuclei within the zebrafish brain. Furthermore, under constant dark (DD) conditions, c-fos shows a significant circadian oscillation. Taken together, these results show that there are numerous areas of the zebrafish central nervous system, which contain deep brain photoreceptors and directly light-entrainable circadian pacemakers. However, there are also multiple brain nuclei, which possess neither, demonstrating a degree of pacemaker complexity that was not previously appreciated. PMID:24465943

Dim light at night increases depressive-like responses in male C3H/HeNHsd mice.

PubMed

Fonken, Laura K; Nelson, Randy J

2013-04-15

Daily patterns of light exposure have become increasingly variable since the widespread adoption of electrical lighting during the 20th century. Seasonal fluctuations in light exposure, shift-work, and transmeridian travel are all associated with alterations in mood. These studies implicate fluctuations in environmental lighting in the development of depressive disorders. Here we argue that exposure to light at night (LAN) may be causally linked to depression. Male C3H/HeNHsd mice, which produce nocturnal melatonin, were housed in either a standard light/dark (LD) cycle or exposed to nightly dim (5 lux) LAN (dLAN). After four weeks in lighting conditions mice underwent behavioral testing and hippocampal tissue was collected at the termination of the study for qPCR. Here were report that mice exposed to dLAN increase depressive-like responses in both a sucrose anhedonia and forced swim test. In contrast to findings in diurnal grass rats, dLAN mice perform comparably to mice housed under dark nights in a hippocampus-dependent learning and memory task. TNFα and IL1β gene expression do not differ between groups, demonstrating that changes in these pro-inflammatory cytokines do not mediate dLAN induced depressive-like responses in mice. BDNF expression is reduced in the hippocampus of mice exposed to dLAN. These results indicate that low levels of LAN can alter mood in mice. This study along with previous work implicates LAN as a potential factor contributing to depression. Further understanding of the mechanisms through which LAN contributes to changes in mood is important for characterizing and treating depressive disorders. Copyright © 2013 Elsevier B.V. All rights reserved.

Transcriptome Analysis in Haematococcus pluvialis: Astaxanthin Induction by High Light with Acetate and Fe2.

PubMed

He, Bangxiang; Hou, Lulu; Dong, Manman; Shi, Jiawei; Huang, Xiaoyun; Ding, Yating; Cong, Xiaomei; Zhang, Feng; Zhang, Xuecheng; Zang, Xiaonan

2018-01-07

Haematococcus pluvialis is a commercial microalga, that produces abundant levels of astaxanthin under stress conditions. Acetate and Fe 2+ are reported to be important for astaxanthin accumulation in H. pluvialis . In order to study the synergistic effects of high light stress and these two factors, we obtained transcriptomes for four groups: high light irradiation (HL), addition of 25 mM acetate under high light (HA), addition of 20 μM Fe 2+ under high light (HF) and normal green growing cells (HG). Among the total clean reads of the four groups, 156,992 unigenes were found, of which 48.88% were annotated in at least one database (Nr, Nt, Pfam, KOG/COG, SwissProt, KEGG, GO). The statistics for DEGs (differentially expressed genes) showed that there were more than 10 thousand DEGs caused by high light and 1800-1900 DEGs caused by acetate or Fe 2+ . The results of DEG analysis by GO and KEGG enrichments showed that, under the high light condition, the expression of genes related to many pathways had changed, such as the pathway for carotenoid biosynthesis, fatty acid elongation, photosynthesis-antenna proteins, carbon fixation in photosynthetic organisms and so on. Addition of acetate under high light significantly promoted the expression of key genes related to the pathways for carotenoid biosynthesis and fatty acid elongation. Furthermore, acetate could obviously inhibit the expression of genes related to the pathway for photosynthesis-antenna proteins. For addition of Fe 2+ , the genes related to photosynthesis-antenna proteins were promoted significantly and there was no obvious change in the gene expressions related to carotenoid and fatty acid synthesis.

Transcriptome dynamics during the transition from anaerobic photosynthesis to aerobic respiration in Rhodobacter sphaeroides 2.4.1.

PubMed

Arai, Hiroyuki; Roh, Jung Hyeob; Kaplan, Samuel

2008-01-01

Rhodobacter sphaeroides 2.4.1 is a facultative photosynthetic anaerobe that grows by anoxygenic photosynthesis under anaerobic-light conditions. Changes in energy generation pathways under photosynthetic and aerobic respiratory conditions are primarily controlled by oxygen tensions. In this study, we performed time series microarray analyses to investigate transcriptome dynamics during the transition from anaerobic photosynthesis to aerobic respiration. Major changes in gene expression profiles occurred in the initial 15 min after the shift from anaerobic-light to aerobic-dark conditions, with changes continuing to occur up to 4 hours postshift. Those genes whose expression levels changed significantly during the time series were grouped into three major classes by clustering analysis. Class I contained genes, such as that for the aa3 cytochrome oxidase, whose expression levels increased after the shift. Class II contained genes, such as those for the photosynthetic apparatus and Calvin cycle enzymes, whose expression levels decreased after the shift. Class III contained genes whose expression levels temporarily increased during the time series. Many genes for metabolism and transport of carbohydrates or lipids were significantly induced early during the transition, suggesting that those endogenous compounds were initially utilized as carbon sources. Oxidation of those compounds might also be required for maintenance of redox homeostasis after exposure to oxygen. Genes for the repair of protein and sulfur groups and uptake of ferric iron were temporarily upregulated soon after the shift, suggesting they were involved in a response to oxidative stress. The flagellar-biosynthesis genes were expressed in a hierarchical manner at 15 to 60 min after the shift. Numerous transporters were induced at various time points, suggesting that the cellular composition went through significant changes during the transition from anaerobic photosynthesis to aerobic respiration. Analyses of these data make it clear that numerous regulatory activities come into play during the transition from one homeostatic state to another.

Proteomics analysis reveals a dynamic diurnal pattern of photosynthesis-related pathways in maize leaves

PubMed Central

Lu, Tiegang; Zhang, Zhiguo

2017-01-01

Plant leaves exhibit differentiated patterns of photosynthesis rates under diurnal light regulation. Maize leaves show a single-peak pattern without photoinhibition at midday when the light intensity is maximized. This mechanism contributes to highly efficient photosynthesis in maize leaves. To understand the molecular basis of this process, an isobaric tag for relative and absolute quantitation (iTRAQ)-based proteomics analysis was performed to reveal the dynamic pattern of proteins related to photosynthetic reactions. Steady, single-peak and double-peak protein expression patterns were discovered in maize leaves, and antenna proteins in these leaves displayed a steady pattern. In contrast, the photosystem, carbon fixation and citrate pathways were highly controlled by diurnal light intensity. Most enzymes in the limiting steps of these pathways were major sites of regulation. Thus, maize leaves optimize photosynthesis and carbon fixation outside of light harvesting to adapt to the changes in diurnal light intensity at the protein level. PMID:28732011

Acute Effects of Morning Light on Plasma Glucose and Triglycerides in Healthy Men and Men with Type 2 Diabetes.

PubMed

Versteeg, Ruth I; Stenvers, Dirk J; Visintainer, Dana; Linnenbank, Andre; Tanck, Michael W; Zwanenburg, Gooitzen; Smilde, Age K; Fliers, Eric; Kalsbeek, Andries; Serlie, Mireille J; la Fleur, Susanne E; Bisschop, Peter H

2017-04-01

Ambient light intensity is signaled directly to hypothalamic areas that regulate energy metabolism. Observational studies have shown associations between ambient light intensity and plasma glucose and lipid levels, but human data on the acute metabolic effects of light are scarce. Since light is the main signal indicating the onset of the diurnal phase of physical activity and food intake in humans, we hypothesized that bright light would affect glucose and lipid metabolism. Therefore, we determined the acute effects of bright light on plasma glucose and lipid concentrations in 2 randomized crossover trials: (1) in 8 healthy lean men and (2) in 8 obese men with type 2 diabetes. From 0730 h, subjects were exposed to either bright light (4000 lux) or dim light (10 lux) for 5 h. After 1 h of light exposure, subjects consumed a 600-kcal mixed meal. Primary endpoints were fasting and postprandial plasma glucose levels. In healthy men, bright light did not affect fasting or postprandial plasma glucose levels. However, bright light increased fasting and postprandial plasma triglycerides. In men with type 2 diabetes, bright light increased fasting and postprandial glucose levels. In men with type 2 diabetes, bright light did not affect fasting triglyceride levels but increased postprandial triglyceride levels. We show that ambient light intensity acutely affects human plasma glucose and triglyceride levels. Our findings warrant further research into the consequences of the metabolic effects of light for the diagnosis and prevention of hyperglycemia and dyslipidemia.

Visible light active 2D C3N4-CdS hetero-junction photocatalyst for effective removal of azo dye by photodegradation

NASA Astrophysics Data System (ADS)

Ghosh Chaudhuri, Rajib; Chaturvedi, Ashwin; Iype, Eldhose

2018-03-01

A hetero-junction two dimensional photocatalyst that consists of organic semiconductor carbon nitride (C3N4) and inorganic semiconductor CdS, which acts as the light harvesting units and heterogeneous catalyst, was developed for the degradation of azo dye methyl orange (MO). Both materials are visible light active semiconductor. So the effective band gap of this heterojunction materials does not significantly change the visible light activity, but the injection of electrons from excited C3N4 to CdS increases the stability of hole-electron pair and that ultimately enhances the photocatalytic activity. This heterojunction catalyst finally can remove 97% of dyes and that is comparatively higher than individual pure materials. Finally, by using DFT analysis the band structure and the level diagrams of this photocatalyst are also analyzed.

Changes in leaf area, nitrogen content and canopy photosynthesis in soybean exposed to an ozone concentration gradient

USDA-ARS?s Scientific Manuscript database

Influences of ozone (O3) on light-saturated rates of photosynthesis in crop leaves have been well documented. To increase our understanding of O3 effects on individual- or stand level productivity, a mechanistic understanding of factors determining canopy photosynthesis is necessary. We used a canop...

Fortress Europe in the Field: Academics, Immigrants, and Methodological Considerations for Educational Studies

ERIC Educational Resources Information Center

Mielants, Eric; Weiner, Melissa F.

2015-01-01

This article addresses the difficulty of local-level qualitative educational research in Amsterdam in light of changes related to contemporary political discourse on decades of immigration, especially from the 1970s onward, and increasingly critical assessments of Dutch education in the literature. It considers recent developments in the…

Coaches' Voices Bring 6 Lessons to Light

ERIC Educational Resources Information Center

Brady, Cheryl H.

2007-01-01

In 1996, the Kansas City (Kan.) Public Schools, a largely poor, urban system, was facing a crisis. Talk at local and state levels was about closing a number of poor-performing schools. The author discusses how the district took matters in hand to make significant changes. Partnering with the local National Education Association leadership,…

Interest Groups, the Courts, and Educational Equality: A Policy Regimes Approach to "Vergara v. California"

ERIC Educational Resources Information Center

Superfine, Benjamin Michael; Thompson, Alea R.

2016-01-01

In "Vergara v. California" (2014), a trial-level court ruled that California laws governing teacher tenure and dismissal were unconstitutional. This study analyzes "Vergara" in light of the shifting use of the courts to promote equal educational opportunities and the changing power bases of educational interest groups,…

Therapeutic effect of forearm low level light treatment on blood flow, oxygenation, and oxygen consumption

NASA Astrophysics Data System (ADS)

Wang, Pengbo; Sun, Jiajing; Meng, Lingkang; Li, Zebin; Li, Ting

2018-02-01

Low level light/laser therapy (LLLT) is considered as a novel, non-invasive, and potential therapy in a variety of psychological and physical conditions, due to its effective intricate photobiomodulation. The mechanism of LLLT is that when cells are stimulated by photons, mitochondria produce a large quantity of ATP, which accelerates biochemical responses in the cell. It is of great significance to gain a clear insight into the change or interplay of various physiological parameters. In this study, we used functional near-infrared spectroscopy (fNIRS) and venous-occlusion plethysmography to measure the LLLT-induced changes in blood flow, oxygenation, and oxygen consumption in human forearms in vivo. Six healthy human participants (4 males and 2 females) were administered with 810-nm light emitted by LED array in ten minutes and blood flow, oxygenation and oxygen consumption were detected in the entire experiment. We found that LLLT induced an increase of blood flow and oxygen consumption on the treated site. Meanwhile, LLLT took a good role in promoting oxygenation of regional tissue, which was indicated by a significant increase of oxygenated hemoglobin concentration (Δ[HbO2]), a nearly invariable deoxygenated hemoglobin concentration (Δ[Hb]) and a increase of differential hemoglobin concentration (Δ[HbD] = Δ[HbO2] - Δ[Hb]). These results not only demonstrate enormous potential of LLLT, but help to figure out mechanisms of photobiomodulation.

Metabolism of trans-3-hexadecenoic acid in broad bean.

PubMed

Harwood, J L; James, A T

1975-01-02

1. Broad bean (Vicia faba) leaves contain rather high concentrations (about 4% of total fatty acids) of the trans-3-hexadecenoic acid. 2. Amounts of the acid increase with the age of the leaves and are absent from etiolated tissue. 3. Changes in the levels of trans-delta-4-hexadecenoic acid can be produced by subjecting the intact plants to various light/dark periods. 4. Chloroplasts isolated from broad-bean leaves show high rates of fatty acid synthesis from [1-14C]acetate. Synthesis is dependent on coenzyme A and ATP but is insensitive to the addition of exogenous acyl carrier protein. 5. The pattern of acids made includes about 20% palmitic, 5% hexadeconoic, 10% stearic and 60% oleic. trans-3-Hexadecenoic acid synthesis was most active in chloroplasts from plants exposed to the dark for 5 days and light for 3 days. 6. Arsenite addition inhibited stearate formation by isolated chloroplasts but resulted in a two-fold stimulation of overall synthesis. 7. The rate of fatty acid synthesis by isolated chloroplasts paralleled the changes in endogenous trans-3-hexadecenoic acid levels in the leaves from which they were isolated.

Highly sensitive and selective dynamic light-scattering assay for TNT detection using p-ATP attached gold nanoparticle.

PubMed

Dasary, Samuel S R; Senapati, Dulal; Singh, Anant Kumar; Anjaneyulu, Yerramilli; Yu, Hongtao; Ray, Paresh Chandra

2010-12-01

TNT is one of the most commonly used nitro aromatic explosives for landmines of military and terrorist activities. As a result, there is an urgent need for rapid and reliable methods for the detection of trace amount of TNT for screenings in airport, analysis of forensic samples, and environmental analysis. Driven by the need to detect trace amounts of TNT from environmental samples, this article demonstrates a label-free, highly selective, and ultrasensitive para-aminothiophenol (p-ATP) modified gold nanoparticle based dynamic light scattering (DLS) probe for TNT recognition in 100 pico molar (pM) level from ethanol:acetonitile mixture solution. Because of the formation of strong π-donor-acceptor interaction between TNT and p-ATP, para-aminothiophenol attached gold nanoparticles undergo aggregation in the presence of TNT, which changes the DLS intensity tremendously. A detailed mechanism for significant DLS intensity change has been discussed. Our experimental results show that TNT can be detected quickly and accurately without any dye tagging in 100 pM level with excellent discrimination against other nitro compounds.

Blue light filtered white light induces depression-like responses and temporary spatial learning deficits in rats.

PubMed

Meng, Qinghe; Lian, Yuzheng; Jiang, Jianjun; Wang, Wei; Hou, Xiaohong; Pan, Yao; Chu, Hongqian; Shang, Lanqin; Wei, Xuetao; Hao, Weidong

2018-04-18

Ambient light has a vital impact on mood and cognitive functions. Blue light has been previously reported to play a salient role in the antidepressant effect via melanopsin. Whether blue light filtered white light (BFW) affects mood and cognitive functions remains unclear. The present study aimed to investigate whether BFW led to depression-like symptoms and cognitive deficits including spatial learning and memory abilities in rats, and whether they were associated with the light-responsive function in retinal explants. Male Sprague-Dawley albino rats were randomly divided into 2 groups (n = 10) and treated with a white light-emitting diode (LED) light source and BFW light source, respectively, under a standard 12 : 12 h L/D condition over 30 days. The sucrose consumption test, forced swim test (FST) and the level of plasma corticosterone (CORT) were employed to evaluate depression-like symptoms in rats. Cognitive functions were assessed by the Morris water maze (MWM) test. A multi-electrode array (MEA) system was utilized to measure electro-retinogram (ERG) responses induced by white or BFW flashes. The effect of BFW over 30 days on depression-like responses in rats was indicated by decreased sucrose consumption in the sucrose consumption test, an increased immobility time in the FST and an elevated level of plasma CORT. BFW led to temporary spatial learning deficits in rats, which was evidenced by prolonged escape latency and swimming distances in the spatial navigation test. However, no changes were observed in the short memory ability of rats treated with BFW. The micro-ERG results showed a delayed implicit time and reduced amplitudes evoked by BFW flashes compared to the white flash group. BFW induces depression-like symptoms and temporary spatial learning deficits in rats, which might be closely related to the impairment of light-evoked output signals in the retina.

Effect of uniaxial stress on electroluminescence, valence band modification, optical gain, and polarization modes in tensile strained p-AlGaAs/GaAsP/n-AlGaAs laser diode structures: Numerical calculations and experimental results

NASA Astrophysics Data System (ADS)

Bogdanov, E. V.; Minina, N. Ya.; Tomm, J. W.; Kissel, H.

2012-11-01

The effects of uniaxial compression in [110] direction on energy-band structures, heavy and light hole mixing, optical matrix elements, and gain in laser diodes with "light hole up" configuration of valence band levels in GaAsP quantum wells with different widths and phosphorus contents are numerically calculated. The development of light and heavy hole mixing caused by symmetry lowering and converging behavior of light and heavy hole levels in such quantum wells under uniaxial compression is displayed. The light or heavy hole nature of each level is established for all considered values of uniaxial stress. The results of optical gain calculations for TM and TE polarization modes show that uniaxial compression leads to a significant increase of the TE mode and a minor decrease of the TM mode. Electroluminescence experiments were performed under uniaxial compression up to 5 kbar at 77 K on a model laser diode structure (p-AlxGa1-xAs/GaAs1-yPy/n-AlxGa1-xAs) with y = 0.16 and a quantum well width of 14 nm. They reveal a maximum blue shift of 27 meV of the electroluminescence spectra that is well described by the calculated change of the optical gap and the increase of the intensity being referred to a TE mode enhancement. Numerical calculations and electroluminescence data indicate that uniaxial compression may be used for a moderate wavelength and TM/TE intensity ratio tuning.

Low-Level Light Therapy with 410 nm Light Emitting Diode Suppresses Collagen Synthesis in Human Keloid Fibroblasts: An In Vitro Study

PubMed Central

Lee, Hyun Soo; Jung, Soo-Eun; Kim, Sue Kyung; Kim, You-Sun; Sohn, Seonghyang

2017-01-01

Background Keloids are characterized by excessive collagen deposition in the dermis, in which transforming growth factor β (TGF-β)/Smad signaling plays an important role. Low-level light therapy (LLLT) is reported as effective in preventing keloids in clinical reports, recently. To date, studies investigating the effect of LLLT on keloid fibroblasts are extremely rare. Objective We investigated the effect of LLLT with blue (410 nm), red (630 nm), and infrared (830 nm) light on the collagen synthesis in keloid fibroblasts. Methods Keloid fibroblasts were isolated from keloid-revision surgery samples and irradiated using 410-, 630-, 830-nm light emitting diode twice, with a 24-hour interval at 10 J/cm2. After irradiation, cells were incubated for 24 and 48 hours and real-time quantitative reverse transcription polymerase chain reaction was performed. Western blot analysis was also performed in 48 hours after last irradiation. The genes and proteins of collagen type I, TGF-β1, Smad3, and Smad7 were analyzed. Results We observed no statistically significant change in the viability of keloid fibroblasts after irradiation. Collagen type I was the only gene whose expression significantly decreased after irradiation at 410 nm when compared to the non-irradiated control. Western blot analysis showed that LLLT at 410 nm lowered the protein levels of collagen type I compared to the control. Conclusion LLLT at 410 nm decreased the expression of collagen type I in keloid fibroblasts and might be effective in preventing keloid formation in their initial stage. PMID:28392641

Low-Level Light Therapy with 410 nm Light Emitting Diode Suppresses Collagen Synthesis in Human Keloid Fibroblasts: An In Vitro Study.

PubMed

Lee, Hyun Soo; Jung, Soo-Eun; Kim, Sue Kyung; Kim, You-Sun; Sohn, Seonghyang; Kim, You Chan

2017-04-01

Keloids are characterized by excessive collagen deposition in the dermis, in which transforming growth factor β (TGF-β)/Smad signaling plays an important role. Low-level light therapy (LLLT) is reported as effective in preventing keloids in clinical reports, recently. To date, studies investigating the effect of LLLT on keloid fibroblasts are extremely rare. We investigated the effect of LLLT with blue (410 nm), red (630 nm), and infrared (830 nm) light on the collagen synthesis in keloid fibroblasts. Keloid fibroblasts were isolated from keloid-revision surgery samples and irradiated using 410-, 630-, 830-nm light emitting diode twice, with a 24-hour interval at 10 J/cm 2 . After irradiation, cells were incubated for 24 and 48 hours and real-time quantitative reverse transcription polymerase chain reaction was performed. Western blot analysis was also performed in 48 hours after last irradiation. The genes and proteins of collagen type I, TGF-β1, Smad3, and Smad7 were analyzed. We observed no statistically significant change in the viability of keloid fibroblasts after irradiation. Collagen type I was the only gene whose expression significantly decreased after irradiation at 410 nm when compared to the non-irradiated control. Western blot analysis showed that LLLT at 410 nm lowered the protein levels of collagen type I compared to the control. LLLT at 410 nm decreased the expression of collagen type I in keloid fibroblasts and might be effective in preventing keloid formation in their initial stage.

Understanding changes of stomatal conductance under different atmospheric humidity levels for different tropical rainforest species in Biosphere 2

NASA Astrophysics Data System (ADS)

Tornito, A. J. G.

2016-12-01

Understanding the dynamics of climate change is one of the biggest questions that scientists across the globe ask today. With understanding climate change comes the need to understand the ecological systems and how their biological and chemical processes contribute to climate change. As ocean ecosystems, rainforests are very productive systems and are responsible for most of the world's carbon budget. To maintain cooler conditions, tropical forests mitigate warming through evapotranspiration. The purpose of this project was to measure short-term plasticity by looking at stomatal conductance levels of different tropical rainforest species of plants in the rainforest, savannah, and desert habitats in the Biosphere 2 facility in Oracle, Arizona. It is known that stomatal conductance is affected by CO2, H2O, and light availability. It has been observed that temperature levels may not affect stomatal conductance because of the variability associated with it. Results indicated that there is a potential trend amongst these rainforest species when placed in different humidity percentage areas. By understanding stomatal conductance in response to humidity, we can better understand how productive rainforest systems are when humidity levels decrease, which may potentially occur as Earth undergoes global climate change.

Antibacterial Mechanism of 405-Nanometer Light-Emitting Diode against Salmonella at Refrigeration Temperature.

PubMed

Kim, Min-Jeong; Yuk, Hyun-Gyun

2017-03-01

The aim of this study was to elucidate the antibacterial mechanism of 405 ± 5-nm light-emitting diode (LED) illumination against Salmonella at 4°C in phosphate-buffered saline (PBS) by determining endogenous coproporphyrin content, DNA oxidation, damage to membrane function, and morphological change. Gene expression levels, including of oxyR , recA , rpoS , sodA , and soxR , were also examined to understand the response of Salmonella to LED illumination. The results showed that Salmonella strains responded differently to LED illumination, revealing that S. enterica serovar Enteritidis (ATCC 13076) and S. enterica subsp. enterica serovar Saintpaul (ATCC 9712) were more susceptible and resistant, respectively, than the 16 other strains tested. There was no difference in the amounts of endogenous coproporphyrin in the two strains. Compared with that in nonilluminated cells, the DNA oxidation levels in illuminated cells increased. In illuminated cells, we observed a loss of efflux pump activity, damage to the glucose uptake system, and changes in membrane potential and integrity. Transmission electron microscopy revealed a disorganization of chromosomes and ribosomes due to LED illumination. The levels of the five genes measured in the nonilluminated and illuminated S Saintpaul cells were upregulated in PBS at a set temperature of 4°C, indicating that increased gene expression levels might be due to a temperature shift and nutrient deficiency rather than to LED illumination. In contrast, only oxyR in S Enteritidis cells was upregulated. Thus, different sensitivities of the two strains to LED illumination were attributed to differences in gene regulation. IMPORTANCE Bacterial inactivation using visible light has recently received attention as a safe and environmentally friendly technology, in contrast with UV light, which has detrimental effects on human health and the environment. This study was designed to understand how 405 ± 5-nm light-emitting diode (LED) illumination kills Salmonella strains at refrigeration temperature. The data clearly demonstrated that the effectiveness of LED illumination on Salmonella strains depended highly on the serotype and strain. Our findings also revealed that its antibacterial mechanism was mainly attributed to DNA oxidation and a loss of membrane functions rather than membrane lipid peroxidation, which has been proposed by other researchers who studied the antibacterial effect of LED illumination by adding exogenous photosensitizers, such as chlorophyllin and hypericin. Therefore, this study suggests that the detailed antibacterial mechanisms of 405-nm LED illumination without additional photosensitizers may differ from that by exogenous photosensitizers. Furthermore, a change in stress-related gene regulation may alter the susceptibility of Salmonella cells to LED illumination at refrigeration temperature. Thus, our study provides new insights into the antibacterial mechanism of 405 ± 5-nm LED illumination on Salmonella cells. Copyright © 2017 American Society for Microbiology.

Antibacterial Mechanism of 405-Nanometer Light-Emitting Diode against Salmonella at Refrigeration Temperature

PubMed Central

Kim, Min-Jeong

2016-01-01

ABSTRACT The aim of this study was to elucidate the antibacterial mechanism of 405 ± 5-nm light-emitting diode (LED) illumination against Salmonella at 4°C in phosphate-buffered saline (PBS) by determining endogenous coproporphyrin content, DNA oxidation, damage to membrane function, and morphological change. Gene expression levels, including of oxyR, recA, rpoS, sodA, and soxR, were also examined to understand the response of Salmonella to LED illumination. The results showed that Salmonella strains responded differently to LED illumination, revealing that S. enterica serovar Enteritidis (ATCC 13076) and S. enterica subsp. enterica serovar Saintpaul (ATCC 9712) were more susceptible and resistant, respectively, than the 16 other strains tested. There was no difference in the amounts of endogenous coproporphyrin in the two strains. Compared with that in nonilluminated cells, the DNA oxidation levels in illuminated cells increased. In illuminated cells, we observed a loss of efflux pump activity, damage to the glucose uptake system, and changes in membrane potential and integrity. Transmission electron microscopy revealed a disorganization of chromosomes and ribosomes due to LED illumination. The levels of the five genes measured in the nonilluminated and illuminated S. Saintpaul cells were upregulated in PBS at a set temperature of 4°C, indicating that increased gene expression levels might be due to a temperature shift and nutrient deficiency rather than to LED illumination. In contrast, only oxyR in S. Enteritidis cells was upregulated. Thus, different sensitivities of the two strains to LED illumination were attributed to differences in gene regulation. IMPORTANCE Bacterial inactivation using visible light has recently received attention as a safe and environmentally friendly technology, in contrast with UV light, which has detrimental effects on human health and the environment. This study was designed to understand how 405 ± 5-nm light-emitting diode (LED) illumination kills Salmonella strains at refrigeration temperature. The data clearly demonstrated that the effectiveness of LED illumination on Salmonella strains depended highly on the serotype and strain. Our findings also revealed that its antibacterial mechanism was mainly attributed to DNA oxidation and a loss of membrane functions rather than membrane lipid peroxidation, which has been proposed by other researchers who studied the antibacterial effect of LED illumination by adding exogenous photosensitizers, such as chlorophyllin and hypericin. Therefore, this study suggests that the detailed antibacterial mechanisms of 405-nm LED illumination without additional photosensitizers may differ from that by exogenous photosensitizers. Furthermore, a change in stress-related gene regulation may alter the susceptibility of Salmonella cells to LED illumination at refrigeration temperature. Thus, our study provides new insights into the antibacterial mechanism of 405 ± 5-nm LED illumination on Salmonella cells. PMID:28003197

Effect of Red and Blue Light on Anthocyanin Accumulation and Differential Gene Expression in Strawberry (Fragaria × ananassa).

PubMed

Zhang, Yunting; Jiang, Leiyu; Li, Yali; Chen, Qing; Ye, Yuntian; Zhang, Yong; Luo, Ya; Sun, Bo; Wang, Xiaorong; Tang, Haoru

2018-04-03

Light conditions can cause quantitative and qualitative changes in anthocyanin. However, little is known about the underlying mechanism of light quality-regulated anthocyanin accumulation in fruits. In this study, light-emitting diodes (LEDs) were applied to explore the effect of red and blue light on strawberry coloration. The results showed contents of total anthocyanins (TA), pelargonidin 3-glucoside (Pg3G) and pelargonidin 3-malonylglucoside (Pg3MG) significantly increased after blue and red light treatment. Pg3G was the major anthocyanin component in strawberry fruits, accounting for more than 80% of TA, whereas Pg3MG accounted for a smaller proportion. Comparative transcriptome analysis was conducted using libraries from the treated strawberries. A total of 1402, 5034, and 3764 differentially-expressed genes (DEGs) were identified in three pairwise comparisons (red light versus white light, RL-VS-WL; blue light versus white light, BL-VS-WL; blue light versus red light, BL-VS-RL), respectively. Photoreceptors and light transduction components remained dynamic to up-regulate the expression of regulatory factors and structural genes related to anthocyanin biosynthesis under red and white light, whereas most genes had low expression levels that were not consistent with the highest total anthocyanin content under blue light. Therefore, the results indicated that light was an essential environmental factor for anthocyanin biosynthesis before the anthocyanin concentration reached saturation in strawberry fruits, and blue light could quickly stimulate the accumulation of anthocyanin in the fruit. In addition, red light might contribute to the synthesis of proanthocyanidins by inducing LAR and ANR .

PCH1 integrates circadian and light-signaling pathways to control photoperiod-responsive growth in Arabidopsis

PubMed Central

Huang, He; Yoo, Chan Yul; Bindbeutel, Rebecca; Goldsworthy, Jessica; Tielking, Allison; Alvarez, Sophie; Naldrett, Michael J; Evans, Bradley S; Chen, Meng; Nusinow, Dmitri A

2016-01-01

Plants react to seasonal change in day length through altering physiology and development. Factors that function to harmonize growth with photoperiod are poorly understood. Here we characterize a new protein that associates with both circadian clock and photoreceptor components, named PHOTOPERIODIC CONTROL OF HYPOCOTYL1 (PCH1). pch1 seedlings have overly elongated hypocotyls specifically under short days while constitutive expression of PCH1 shortens hypocotyls independent of day length. PCH1 peaks at dusk, binds phytochrome B (phyB) in a red light-dependent manner, and co-localizes with phyB into photobodies. PCH1 is necessary and sufficient to promote the biogenesis of large photobodies to maintain an active phyB pool after light exposure, potentiating red-light signaling and prolonging memory of prior illumination. Manipulating PCH1 alters PHYTOCHROME INTERACTING FACTOR 4 levels and regulates light-responsive gene expression. Thus, PCH1 is a new factor that regulates photoperiod-responsive growth by integrating the clock with light perception pathways through modulating daily phyB-signaling. DOI: http://dx.doi.org/10.7554/eLife.13292.001 PMID:26839287

Manifestation of Hyperandrogenism in the Continuous Light Exposure-Induced PCOS Rat Model

PubMed Central

Kang, Xuezhi; Jia, Lina; Shen, Xueyong

2015-01-01

Polycystic ovary syndrome (PCOS) is a complex endocrine and metabolic disorder, and its pathogenesis has yet to be completely clarified. A fully convincing animal model has not been established for PCOS. In earlier studies, researchers have shown that the exposure of rats to continuous light can induce PCOS; nevertheless, hyperandrogenism, a key characteristic observed in human PCOS, has not been reported previously. In the present study, we found that (1) body weights decreased in female rats in a continuous light environment with both ovarian and uterine augmentation; (2) the estrous cycle in rats under continuous light environment was disordered, and polycystic ovary-like changes occurred, accompanied with fur loss and lethargy; and (3) serum testosterone levels in rats in a continuous light environment significantly increased. Our data suggest that continuous light can lead to the occurrence of PCOS in female rats without the need for drugs; this is a reasonable PCOS animal model that is more consistent with the natural disease state in humans; and poor sleep habits or negligence of sleep hygiene may be an important lifestyle factor in pathogenesis of PCOS. PMID:26064969

Melatonin administration modifies circadian motor activity under constant light depending on the lighting conditions during suckling.

PubMed

Carpentieri, Agata R; Oliva, Clara; Díez-Noguera, Antoni; Cambras, Trinitat

2015-01-01

Early lighting conditions have been described to produce long-term effects on circadian behavior, which may also influence the response to agents acting on the circadian system. It has been suggested that melatonin (MEL) may act on the circadian pacemaker and as a scavenger of reactive oxygen and nitrogen species. Here, we studied the oxidative and behavioral changes caused by prolonged exposure to constant light (LL) in groups of rats that differed in MEL administration and in lighting conditions during suckling. The rats were exposed to either a light-dark cycle (LD) or LL. At 40 days old, rats were treated for 2 weeks with a daily subcutaneous injection of MEL (10 mg/kg body weight) or a vehicle at activity onset. Blood samples were taken before and after treatment, to determine catalase (CAT) activity and nitrite level in plasma. As expected, LL-reared rats showed a more stable motor activity circadian rhythm than LD rats. MEL treatment produced more reactivity in LD- than in LL rats, and was also able to alter the phase of the rhythm in LD rats. There were no significant differences in nitrite levels or CAT activity between the groups, although both variables increased with time. Finally, we also tested depressive signs by means of sucrose consumption, and anhedonia was found in LD males treated with MEL. The results suggest that the lighting conditions in early infancy are important for the long-term functionality of the circadian system, including rhythm manifestation, responses to MEL and mood alterations.

Regulation of melanopsin expression.

PubMed

Hannibal, Jens

2006-01-01

Circadian rhythms in mammals are adjusted daily to the environmental day/night cycle by photic input via the retinohypothalamic tract (RHT). Retinal ganglion cells (RGCs) of the RHT constitute a separate light-detecting system in the mammalian retina used for irradiance detection and for transmission to the circadian system and other non-imaging forming processes in the brain. The RGCs of the RHT are intrinsically photosensitive due to the expression of melanopsin, an opsin-like photopigment. This notion is based on anatomical and functional data and on studies of mice lacking melanopsin. Furthermore, heterologous expression of melanopsin in non-neuronal mammalian cell lines was found sufficient to render these cells photosensitive. Even though solid evidence regarding the function of melanopsin exists, little is known about the regulation of melanopsin gene expression. Studies in albino Wistar rats showed that the expression of melanopsin is diurnal at both the mRNA and protein levels. The diurnal changes in melanopsin expression seem, however, to be overridden by prolonged exposure to light or darkness. Significant increase in melanopsin expression was observed from the first day in constant darkness and the expression continued to increase during prolonged exposure in constant darkness. Prolonged exposure to constant light, on the other hand, decreased melanopsin expression to an almost undetectable level after 5 days of constant light. The induction of melanopsin by darkness was even more pronounced if darkness was preceded by light suppression for 5 days. These observations show that dual mechanisms regulate melanopsin gene expression and that the intrinsic light-responsive RGCs in the albino Wistar rat adapt their expression of melanopsin to environmental light and darkness.

Quasimodo mediates daily and acute light effects on Drosophila clock neuron excitability.

PubMed

Buhl, Edgar; Bradlaugh, Adam; Ogueta, Maite; Chen, Ko-Fan; Stanewsky, Ralf; Hodge, James J L

2016-11-22

We have characterized a light-input pathway regulating Drosophila clock neuron excitability. The molecular clock drives rhythmic electrical excitability of clock neurons, and we show that the recently discovered light-input factor Quasimodo (Qsm) regulates this variation, presumably via an Na + , K + , Cl - cotransporter (NKCC) and the Shaw K + channel (dK V 3.1). Because of light-dependent degradation of the clock protein Timeless (Tim), constant illumination (LL) leads to a breakdown of molecular and behavioral rhythms. Both overexpression ( OX ) and knockdown ( RNAi ) of qsm, NKCC, or Shaw led to robust LL rhythmicity. Whole-cell recordings of the large ventral lateral neurons (l-LNv) showed that altering Qsm levels reduced the daily variation in neuronal activity: qsm OX led to a constitutive less active, night-like state, and qsm RNAi led to a more active, day-like state. Qsm also affected daily changes in K + currents and the GABA reversal potential, suggesting a role in modifying membrane currents and GABA responses in a daily fashion, potentially modulating light arousal and input to the clock. When directly challenged with blue light, wild-type l-LNvs responded with increased firing at night and no net response during the day, whereas altering Qsm, NKKC, or Shaw levels abolished these day/night differences. Finally, coexpression of Shaw OX and NKCC RNAi in a qsm mutant background restored LL-induced behavioral arrhythmicity and wild-type neuronal activity patterns, suggesting that the three genes operate in the same pathway. We propose that Qsm affects both daily and acute light effects in l-LNvs probably acting on Shaw and NKCC.

Quasimodo mediates daily and acute light effects on Drosophila clock neuron excitability

PubMed Central

Bradlaugh, Adam; Ogueta, Maite; Chen, Ko-Fan; Stanewsky, Ralf; Hodge, James J. L.

2016-01-01

We have characterized a light-input pathway regulating Drosophila clock neuron excitability. The molecular clock drives rhythmic electrical excitability of clock neurons, and we show that the recently discovered light-input factor Quasimodo (Qsm) regulates this variation, presumably via an Na+, K+, Cl− cotransporter (NKCC) and the Shaw K+ channel (dKV3.1). Because of light-dependent degradation of the clock protein Timeless (Tim), constant illumination (LL) leads to a breakdown of molecular and behavioral rhythms. Both overexpression (OX) and knockdown (RNAi) of qsm, NKCC, or Shaw led to robust LL rhythmicity. Whole-cell recordings of the large ventral lateral neurons (l-LNv) showed that altering Qsm levels reduced the daily variation in neuronal activity: qsmOX led to a constitutive less active, night-like state, and qsmRNAi led to a more active, day-like state. Qsm also affected daily changes in K+ currents and the GABA reversal potential, suggesting a role in modifying membrane currents and GABA responses in a daily fashion, potentially modulating light arousal and input to the clock. When directly challenged with blue light, wild-type l-LNvs responded with increased firing at night and no net response during the day, whereas altering Qsm, NKKC, or Shaw levels abolished these day/night differences. Finally, coexpression of ShawOX and NKCCRNAi in a qsm mutant background restored LL-induced behavioral arrhythmicity and wild-type neuronal activity patterns, suggesting that the three genes operate in the same pathway. We propose that Qsm affects both daily and acute light effects in l-LNvs probably acting on Shaw and NKCC. PMID:27821737

Anxiolytic-like effects of restraint during the dark cycle in adolescent mice.

PubMed

Ota, Yuki; Ago, Yukio; Tanaka, Tatsunori; Hasebe, Shigeru; Toratani, Yui; Onaka, Yusuke; Hashimoto, Hitoshi; Takuma, Kazuhiro; Matsuda, Toshio

2015-05-01

Stress during developmental stage may cause psychological morbidities, and then the studies on stress are important in adolescent rodents. Restraint is used as a common stressor in rodents and the effects of restraint during the light cycle have been studied, but those of restraint during the dark cycle have not. The present study examined the effects of restraint during the light and dark cycles on anxiety behaviors in adolescent mice. Restraint for 3h during either the light or dark cycle impaired memory function in the fear conditioning test, but did not affect locomotor activity. In the elevated plus-maze test, restraint during the dark cycle reduced anxiety-like behaviors in mice. Repeated exposure to a 3-h period dark cycle restraint for 2 weeks had a similar anxiolytic-like effect. In contrast, restraint for 3h during the light cycle produced anxiety behavior in adolescent, but not adult, mice. The light cycle stress increased plasma corticosterone levels, and elevated c-Fos expression in the prefrontal cortex, paraventricular hypothalamic nucleus, basolateral amygdala and dentate gyrus, and enhanced serotonin turnover in the hippocampus and striatum, while the dark cycle stress did not. There was no difference in the stress-mediated reduction in pentobarbital-induced sleeping time between dark and light cycle restraint. These findings suggest that the anxiolytic effect of dark cycle restraint is mediated by corticosterone, serotonin or γ-aminobutyric acid-independent mechanisms, although the anxiogenic effect of light cycle restraint is associated with changes in plasma corticosterone levels and serotonin turnover in specific brain regions. Copyright © 2015 Elsevier B.V. All rights reserved.

Pressure-sensitive optrode

DOEpatents

Hirschfeld, T.B.

1985-04-09

An apparatus and method are disclosed for sensing changes in pressure and for generating optical signals related to changes in pressure. Light from a fiber optic is directed to a movable surface which is coated with a light-responsive material, and which moves relative to the end of the fiber optic in response to changes in pressure. The same fiber optic collects a portion of the reflected or emitted light from the movable surface. Changes in pressure are determined by measuring changes in the amount of light collected. 5 figs.

Elevated Ambient Light and Temperature Constrain Light Perception in Arctic Krill

NASA Astrophysics Data System (ADS)

Cohen, J.; Jørgen, B.; Moline, M. A.; Johnsen, G.

2016-02-01

Krill play an important role in polar ecosystems as grazers on phytoplankton and microzooplankton, as well as in the subsequent transfer of this energy to higher trophic levels including fish, birds, and marine mammals. In the Barents Sea ecosystem, krill are a particularly important food source sustaining the region's extensive fisheries production. Climate variability over the past half-century, including advection of warmer North Atlantic water and boreal euphausiid taxa, has impacted both krill and fish populations in the Barents Sea, as well as dependencies between them. To better understand these dependencies in the context of climate warming, sea ice loss, and increased winter/spring light levels, we examined temperature- and light-acclimation effects on the visual physiology of krill, which utilize vision for both capturing prey and avoiding predators. Here we show that both elevated temperature and light acclimation lead to changes in visual function in krill Thysanoessa inermis collected from Kongsfjord (Svalbard) in late winter. We found that krill eyes were faster, but less sensitive, in warmer and brighter conditions. Predicting the ecological implications of such physiological shifts is challenging. When coupled with models of the underwater light field and visual perception, these findings suggest that krill in the Barents Sea may be more effective at evading fish predators under future climate scenarios with increased North Atlantic water influence. However, shoaling of krill during the daytime phase of their diel vertical migration could oppose this and favor visual predation on krill by fish.

Photosynthetic response of Eriophorum vaginatum to in situ shrub shading in tussock tundra of northern Alaska

NASA Astrophysics Data System (ADS)

Anderson-Smith, A.; Pattison, R.; Sullivan, P.; Welker, J. M.

2009-12-01

Eriophorum vaginatum (Cotton Grass) is an important component of moist acidic tussock tundra, a plant community that appears to be undergoing changes in species composition associated with climate warming. This species is one of the most abundant in the arctic tundra, and provides important forage for caribou in their calving grounds on the Arctic Coastal Plain and along their migratory route through the foothills of Alaska. Recently, remote sensing data, repeat photography and plot-level measurements have indicated that shrub abundance is increasing while Eriophorum abundance is either constant or decreasing. One possible explanation for the reduction of Eriophorum while Betula nana is increasing, is that lower light levels in the taller Betula canopy may be constraining Eriophorum photosynthesis and subsequently reducing plant growth. This study measured the effect of shading on the light response of Eriphorum leaf photosynthesis in four different sites near Toolik Lake Alaska during the summer of 2009. Measurements were taken in: 1) a shrub patch within the drift zone of the ITEX long term snow fence experiment, 2) an LTER shade house (50% shading) built in 1989, 3) water track site 1 and water track site 2 (i.e. control areas with no experimental manipulations) Average photosynthetic rates for Eriophorum at a light level of 800 PAR varied from 3.8 to 10.9 umol m-2 s-1 and were not significantly different in shaded and unshaded areas. This study indicates that shading by shrubs does not appear to be altering the light response of Eriophorum nor does long-term shading by itself eliminate Eriophorum from the community. An alternative explanation for the decline of Eriophorum while Betula increases in abundance under changing climates may be related to plant and soil mineral nutrition, plant water relations or biotic processes involving herbivores.

EXTRASOLAR STORMS: PRESSURE-DEPENDENT CHANGES IN LIGHT-CURVE PHASE IN BROWN DWARFS FROM SIMULTANEOUS HST AND SPITZER OBSERVATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Hao; Apai, Dániel; Karalidi, Theodora

We present Spitzer /Infrared Array Camera Ch1 and Ch2 monitoring of six brown dwarfs during eight different epochs over the course of 20 months. For four brown dwarfs, we also obtained simulataneous Hubble Space Telescope ( HST )/WFC3 G141 grism spectra during two epochs and derived light curves in five narrowband filters. Probing different pressure levels in the atmospheres, the multiwavelength light curves of our six targets all exhibit variations, and the shape of the light curves evolves over the timescale of a rotation period, ranging from 1.4 to 13 hr. We compare the shapes of the light curves andmore » estimate the phase shifts between the light curves observed at different wavelengths by comparing the phase of the primary Fourier components. We use state-of-the-art atmosphere models to determine the flux contribution of different pressure layers to the observed flux in each filter. We find that the light curves that probe higher pressures are similar and in phase, but are offset and often different from the light curves that probe lower pressures. The phase differences between the two groups of light curves suggest that the modulations seen at lower and higher pressures may be introduced by different cloud layers.« less

Effects of radiation upon the light-sensing elements of the retina as characterized by scanning electron microscopy

NASA Technical Reports Server (NTRS)

Malachowski, M. J.; Tobias, C. A.; Leith, J. T.

1977-01-01

A model system using Necturus maculosus, the common mudpuppy, was established for evaluating effects of radiation upon the light-sensing elements of the retina. Accelerated heavy ions of helium and neon from the Berkeley Bevalac were used. A number of criteria were chosen to characterize radiation damage by observing morphological changes with the scanning electron microscope. The studies indicated retina sensitivity to high-LET (neon) particles at radiation levels below 10 rads (7 particles per visual element) whereas no significant effects were seen from fast helium ions below 50 rads.

Theoretical study on the ultra-narrow bandwidth tunable atomic filter with electromagnetically induced transparency

NASA Astrophysics Data System (ADS)

Liu, Yang; Li, Shu-qing; Feng, Zhong-ying; Liu, Xiao-fei; Gao, Jin-yue

2016-12-01

To obtain the weak signal light detection from the high background noise, we present a theoretical study on the ultra-narrow bandwidth tunable atomic filter with electromagnetically induced transparency. In a three-level Λ -type atomic system in the rubidium D1 line, the bandwidth of the EIT atomic filter is narrowed to ~6.5 \\text{MHz} . And the single peak transmission of the filter can be up to 86% . Moreover, the transmission wavelength can be tuned by changing the coupling light frequency. This theoretical scheme can also be applied to other alkali atomic systems.

Effect of Light Availability on the Interaction between Maritime Pine and the Pine Weevil: Light Drives Insect Feeding Behavior But Also the Defensive Capabilities of the Host

PubMed Central

Suárez-Vidal, Estefanía; López-Goldar, Xosé; Sampedro, Luis; Zas, Rafael

2017-01-01

Light is a major environmental factor that may determine the interaction between plants and herbivores in several ways, including top-down effects through changes in herbivore behavior and bottom-up effects mediated by alterations of plant physiology. Here we explored the relative contribution of these two regulation processes to the outcome of the interaction of pine trees with a major forest pest, the pine weevil (Hylobius abietis). We studied to what extent light availability influence insect feeding behavior and/or the ability of pines to produce induced defenses in response to herbivory. For this purpose, 3-year old Pinus pinaster plants from three contrasting populations were subjected to 6 days of experimental herbivory by the pine weevil under two levels of light availability (complete darkness or natural sunlight) independently applied to the plant and to the insect in a fully factorial design. Light availability strongly affected the pine weevil feeding behavior. The pine weevil fed more and caused larger feeding scars in darkness than under natural sunlight. Besides, under the more intense levels of weevil damage (i.e., those registered with insects in darkness), light availability also affected the pine’s ability to respond to insect feeding by producing induced resin defenses. These results were consistent across the three studied populations despite they differed in weevil susceptibility and inducibility of defenses. Morocco was the most damaged population and the one that induced more defensive compounds. Overall, results indicate that light availability modulates the outcome of the pine–weevil interactions through both bottom-up and top-down regulation mechanisms. PMID:28912787

Dim light at night provokes depression-like behaviors and reduces CA1 dendritic spine density in female hamsters.

PubMed

Bedrosian, Tracy A; Fonken, Laura K; Walton, James C; Haim, Abraham; Nelson, Randy J

2011-08-01

The prevalence of major depression has increased in recent decades; however, the underlying causes of this phenomenon remain unspecified. One environmental change that has coincided with elevated rates of depression is increased exposure to artificial light at night. Shift workers and others chronically exposed to light at night are at increased risk of mood disorders, suggesting that nighttime illumination may influence brain mechanisms mediating affect. We tested the hypothesis that exposure to dim light at night may impact affective responses and alter morphology of hippocampal neurons. Ovariectomized adult female Siberian hamsters (Phodopus sungorus) were housed for 8 weeks in either a light/dark cycle (LD) or a light/dim light cycle (DM), and then behavior was assayed. DM-hamsters displayed more depression-like responses in the forced swim and the sucrose anhedonia tests compared with LD-hamsters. Conversely, in the elevated plus maze DM-hamsters reduced anxiety-like behaviors. Brains from the same animals were processed using the Golgi-Cox method and hippocampal neurons within CA1, CA3, and the dentate gyrus were analyzed for morphological characteristics. In CA1, DM-hamsters significantly reduced dendritic spine density on both apical and basilar dendrites, an effect which was not mediated by baseline cortisol, as concentrations were equivalent between groups. These results demonstrate dim light at night is sufficient to reduce synaptic spine connections to CA1. Importantly, the present results suggest that night-time low level illumination, comparable to levels that are pervasive in North America and Europe, may contribute to the increasing prevalence of mood disorders. Copyright © 2011 Elsevier Ltd. All rights reserved.

Untargeted Metabolomics Reveals Predominant Alterations in Lipid Metabolism Following Light Exposure in Broccoli Sprouts

PubMed Central

Maldini, Mariateresa; Natella, Fausta; Baima, Simona; Morelli, Giorgio; Scaccini, Cristina; Langridge, James; Astarita, Giuseppe

2015-01-01

The consumption of vegetables belonging to the family Brassicaceae (e.g., broccoli and cauliflower) is linked to a reduced incidence of cancer and cardiovascular diseases. The molecular composition of such plants is strongly affected by growing conditions. Here we developed an unbiased metabolomics approach to investigate the effect of light and dark exposure on the metabolome of broccoli sprouts and we applied such an approach to provide a bird’s-eye view of the overall metabolic response after light exposure. Broccoli seeds were germinated and grown hydroponically for five days in total darkness or with a light/dark photoperiod (16 h light/8 h dark cycle). We used an ultra-performance liquid-chromatography system coupled to an ion-mobility, time-of-flight mass spectrometer to profile the large array of metabolites present in the sprouts. Differences at the metabolite level between groups were analyzed using multivariate statistical analyses, including principal component analysis and correlation analysis. Altered metabolites were identified by searching publicly available and in-house databases. Metabolite pathway analyses were used to support the identification of subtle but significant changes among groups of related metabolites that may have gone unnoticed with conventional approaches. Besides the chlorophyll pathway, light exposure activated the biosynthesis and metabolism of sterol lipids, prenol lipids, and polyunsaturated lipids, which are essential for the photosynthetic machinery. Our results also revealed that light exposure increased the levels of polyketides, including flavonoids, and oxylipins, which play essential roles in the plant’s developmental processes and defense mechanism against herbivores. This study highlights the significant contribution of light exposure to the ultimate metabolic phenotype, which might affect the cellular physiology and nutritional value of broccoli sprouts. Furthermore, this study highlights the potential of an unbiased omics approach for the comprehensive study of the metabolism. PMID:26084047

Adaptations in rod outer segment disc membranes in response to environmental lighting conditions.

PubMed

Rakshit, Tatini; Senapati, Subhadip; Parmar, Vipul M; Sahu, Bhubanananda; Maeda, Akiko; Park, Paul S-H

2017-10-01

The light-sensing rod photoreceptor cell exhibits several adaptations in response to the lighting environment. While adaptations to short-term changes in lighting conditions have been examined in depth, adaptations to long-term changes in lighting conditions are less understood. Atomic force microscopy was used to characterize the structure of rod outer segment disc membranes, the site of photon absorption by the pigment rhodopsin, to better understand how photoreceptor cells respond to long-term lighting changes. Structural properties of the disc membrane changed in response to housing mice in constant dark or light conditions and these adaptive changes required output from the phototransduction cascade initiated by rhodopsin. Among these were changes in the packing density of rhodopsin in the membrane, which was independent of rhodopsin synthesis and specifically affected scotopic visual function as assessed by electroretinography. Studies here support the concept of photostasis, which maintains optimal photoreceptor cell function with implications in retinal degenerations. Copyright © 2017 Elsevier B.V. All rights reserved.

Flexible polymer waveguides for light-activated therapy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kim, Moonseok; Kwok, Sheldon J. J.; Lin, Harvey H.; Lee, Dong Hee; Yun, Seok Hyun

2017-02-01

Conventional light-activated therapies, such as photodynamic therapy (PDT), photochemical tissue bonding (PTB), collagen crosslinking (CXL), low-level light therapy (LLLT), and antimicrobial therapy utilize external light sources and light propagation through free space, limiting treatment to accessible and superficial areas of the body. Recent progress has been made in developing biocompatible polymer waveguides to enhance light delivery to deep tissues. To further expand clinical utility, waveguides should be flexible and tough enough to enable use in anatomically difficult-to-reach regions, while having the requisite optical properties to achieve uniform and efficient illumination of the target area. Here, we present a new class of flexible polymer waveguides optimized for uniform light extraction into tissues. Our slab waveguides comprise two designs: first, a flexible polydimethylsiloxane (PDMS) based elastomer for CXL, and second, a tough polyacrylamide and alginate hydrogel for large-area phototherapies. Our waveguides are optically transparent in the visible wavelengths (400-750 nm) and a multimode fiber is used to couple light into the waveguide. We characterized the light propagation through the waveguides and light extraction into tissue, and validated our results with optical simulation. By changing the thickness and scattering properties, uniform light extraction through the length of the waveguide could be achieved. We demonstrate proof-of-concept scleral photo-crosslinking of an ex vivo porcine eyeball for prevention of myopia.

'Implementation deficit' and 'street-level bureaucracy': policy, practice and change in the development of community nursing issues.

PubMed

Bergen, Ann; While, Alison

2005-01-01

The present paper examines the mechanisms by which health and social care policies put forward by the Government may be translated into community nursing practice. Data from a research project on community nurse case managers were re-examined in the light of two classic theories often cited by policy analysts (i.e. implementation theory and 'street-level bureaucracy'). It was found that the extent to which nurses adopted the case management role, and the model of choice, depended on four major interrelated variables, namely: (1) the clarity of policy guidance; (2) the extent to which it coincided with professional (nursing) values; (3) local practices and policies; and (4) the personal vision of the community nurse. It is argued that this framework may have wider relevance, and this was tested out in two ways. First, major change in one of these variables (Government policy) over time was analysed for its effect on case management practice via the remaining variables. Secondly, an unrelated, but policy-initiated, nursing issue (nurse prescribing) was briefly examined in the light of the framework. It is suggested that this framework may be of some use when considering the likely practice response to policy-related changes in community nursing.

Phytochrome-Mediated Detection of Changes in Reflected Light

PubMed Central

Mancinelli, Alberto L.

1991-01-01

Measurements of phytochrome photoequilibria and photoconversion rates in vivo, in seedlings of Cucurbita pepo L. exposed to light in growth chambers, indicate that significant changes in the state of phytochrome can be brought about by changes in the quality and quantity of the light reflected from the walls of the growth chambers. The changes in reflected light, although large, were small in terms of the total radiation (direct light from the lamps plus wall-reflected light) to which the seedlings were exposed. The conditions used were approximate simulations of direct and reflected sunlight conditions in the natural environment. Keeping in mind the limitations imposed by the approximation of the simulations, the results from this study are consistent with the hypothesis that, in the natural environment, a plant might be capable of detecting the presence of nearby plants, before being shaded by them, through the phytochrome-mediated perception of changes in reflected light. PMID:16667942

Possible molecular mechanism underlying cadmium-induced circadian rhythms disruption in zebrafish

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Bo; Chen, Tian-Ming; Zhong, Yingbin

This study was aimed to explore the mechanisms underlying cadmium-induced circadian rhythms disruption. Two groups of zebrafish larvae treated with or without 5 ppm CdCl{sub 2} were incubated in a photoperiod of 14-h light/10-h dark conditions. The mRNA levels of clock1a, bmal1b, per2 and per1b in two groups were determined. Microarray data were generated in two group of samples. Differential expression of genes were identified and the changes in expression level for some genes were validated by RT-PCR. Finally, Gene Ontology functional and KEGG pathway enrichment analysis of differentially expressed genes (DEGs) were performed. In comparison with normal group, the mRNAmore » levels of clock1a, bmal1b, and per2 were significantly changed and varied over the circadian cycle in CdCl2-treated group. DEGs were obtained from the light (84 h, ZT12) and dark (88 h, ZT16) phase. In addition, G-protein coupled receptor protein signaling pathway and immune response were both enriched by DEGs in both groups. While, proteolysis and amino acid metabolism were found associated with DEGs in light phase, and Neuroactive ligand-receptor interaction and oxidation-reduction process were significantly enriched by DEGs in dark phase. Besides, the expression pattern of genes including hsp70l and or115-11 obtained by RT-PCR were consistent with those obtained by microarray analysis. As a consequence, cadmium could make significant effects on circadian rhythms through immune response and G protein-coupled receptor signaling pathway. Besides, between the dark and the light phase, the mechanism by which cadmium inducing disruption of circadian rhythms were different to some extent. - Highlights: • Cadmium could affect the expression levels of circadian rhythm-related genes. • Genes expression in microarray data were consistent with those in RT-PCR analysis. • Immune response and G protein-coupled receptor signaling pathway were identified. • Cadmium induces circadian rhythm disruption by different mechanism in day and night.« less

Session 21.2 - Measurement of Light at Night

NASA Astrophysics Data System (ADS)

Wainscoat, Richard J.

2016-10-01

The introduction of the mercury vapor lamp for general lighting in the 1930s probably marked the beginning of significant light pollution. Lighting levels have increased slowly, year-to-year, with sky brightness levels increasing only slowly on timescales of a year; no measurement protocols or instruments existed to quantify this increase. However, on timescales of 10-20 years, or on generational timescales, the increases in night sky levels, particularly in urban areas, have been dramatic. Younger people speak with their parents or grandparents who remark how beautiful the sky used to be, and how many stars they could see when they when they were younger. Older people can themselves remember how many stars were visible in the sky when they were younger. Whole generations of children now grow up without ever seeing the Milky Way. Society has not had tools to easily measure sky brightness, and monitoring from space has only recently become available. A subtle increase of 10% sky brightness per year, for example, is not noticeable to the human eye on the time scale of a year, and has been tolerated by society. But such an increase compounds to an increase of a factor 2.6 in 10 years, 6.7 in 20 years, and a factor 45 in 40 years, corresponding to a dramatic increase in sky brightness, an almost complete loss in ability to see faint objects in the night sky, and rendering the sky unusable for most forms of astronomy. The most striking examples are the urban observatories found in many major cities that can no longer be used. Session 2 was primarily focused on measurement of light at night, with an emphasis on measurement of light pollution. It comprised of 6 papers that are summarized below. Over the last decade, our ability to measure light pollution has grown tremendously, and the instrumentation needed to produce reliable quantitative measurements has become much more affordable, and now includes consumer grade digital cameras and even smart phones. During this same time period, light pollution has continued to grow. The widespread changes from mostly high-pressure sodium lighting to LED lighting that are now occurring make continued monitoring and measurement of light pollution particularly important into the future. Complete presentations may be viewed at: http://www.noao.edu/education/IAUGA2015FM21

Acute Effects of Morning Light on Plasma Glucose and Triglycerides in Healthy Men and Men with Type 2 Diabetes

PubMed Central

Versteeg, Ruth I.; Stenvers, Dirk J.; Visintainer, Dana; Linnenbank, Andre; Tanck, Michael W.; Zwanenburg, Gooitzen; Smilde, Age K.; Fliers, Eric; Kalsbeek, Andries; Serlie, Mireille J.; la Fleur, Susanne E.; Bisschop, Peter H.

2017-01-01

Ambient light intensity is signaled directly to hypothalamic areas that regulate energy metabolism. Observational studies have shown associations between ambient light intensity and plasma glucose and lipid levels, but human data on the acute metabolic effects of light are scarce. Since light is the main signal indicating the onset of the diurnal phase of physical activity and food intake in humans, we hypothesized that bright light would affect glucose and lipid metabolism. Therefore, we determined the acute effects of bright light on plasma glucose and lipid concentrations in 2 randomized crossover trials: (1) in 8 healthy lean men and (2) in 8 obese men with type 2 diabetes. From 0730 h, subjects were exposed to either bright light (4000 lux) or dim light (10 lux) for 5 h. After 1 h of light exposure, subjects consumed a 600-kcal mixed meal. Primary endpoints were fasting and postprandial plasma glucose levels. In healthy men, bright light did not affect fasting or postprandial plasma glucose levels. However, bright light increased fasting and postprandial plasma triglycerides. In men with type 2 diabetes, bright light increased fasting and postprandial glucose levels. In men with type 2 diabetes, bright light did not affect fasting triglyceride levels but increased postprandial triglyceride levels. We show that ambient light intensity acutely affects human plasma glucose and triglyceride levels. Our findings warrant further research into the consequences of the metabolic effects of light for the diagnosis and prevention of hyperglycemia and dyslipidemia. PMID:28470119

Reverse switching of surface roughness in a self-organized polydomain liquid crystal coating.

PubMed

Liu, Danqing; Liu, Ling; Onck, Patrick R; Broer, Dirk J

2015-03-31

In this work we propose randomly ordered polydomain nematic liquid crystal polymer networks to reversibly generate notable jagged relief patterns at a polymer coating surface by light illumination. The domain size is controlled by the addition of traces of partly insoluble fluorinated acrylate. The photoresponse of the coating is induced by a small amount of copolymerized azobenzene monomers. Upon exposure to UV light, azobenzene undergoes trans to cis isomerization, resulting in a change in molecular order and packing within each domain. The extent of this effect and its directionality depends on the domain orientation. Localized to domain level, this morphological change forms large 3D spikes at the surface with a modulation amplitude of more than 20% of the initial thickness. The process is reversible; the surface topographical patterns erase within 10 s by stopping the light exposure. A finite element model is applied to simulate the surface topography changes of the polydomain coating. The simulations describe the formation of the topographic features in terms of light absorption and isomerization process as a function of the director orientation. The random director distribution leads to surface structures which were found to be in close agreement with the ones measured by interference microscopy. The effect of domain size on surface roughness and depth modulation was explored and related to the internal mechanical constraints. The use of nematic liquid crystal polydomains confined in a polymer network largely simplifies the fabrication of smart coatings with a prominent triggered topographic response.

Multi-Level, Multi Time-Scale Fluorescence Intermittency of Photosynthetic LH2 Complexes: A Precursor of Non-Photochemical Quenching?

PubMed

Schörner, Mario; Beyer, Sebastian Reinhardt; Southall, June; Cogdell, Richard J; Köhler, Jürgen

2015-11-05

The light harvesting complex LH2 is a chromoprotein that is an ideal system for studying protein dynamics via the spectral fluctuations of the emission of its intrinsic chromophores. We have immobilized these complexes in a polymer film and studied the fluctuations of the fluorescence intensity from individual complexes over 9 orders of magnitude in time. Combining time-tagged detection of single photons with a change-point analysis has allowed the unambigeous identification of the various intensity levels due to the huge statistical basis of the data set. We propose that the observed intensity level fluctuations reflect conformational changes of the protein backbone that might be a precursor of the mechanism from which nonphotochemical quenching of higher plants has evolved.

Light-Dark Changes in Cytosolic Nitrate Pools Depend on Nitrate Reductase Activity in Arabidopsis Leaf Cells1[w

PubMed Central

Cookson, Sarah J.; Williams, Lorraine E.; Miller, Anthony J.

2005-01-01

Several different cellular processes determine the size of the metabolically available nitrate pool in the cytoplasm. These processes include not only ion fluxes across the plasma membrane and tonoplast but also assimilation by the activity of nitrate reductase (NR). In roots, the maintenance of cytosolic nitrate activity during periods of nitrate starvation and resupply (M. van der Leij, S.J. Smith, A.J. Miller [1998] Planta 205: 64–72; R.-G. Zhen, H.-W. Koyro, R.A. Leigh, A.D. Tomos, A.J. Miller [1991] Planta 185: 356–361) suggests that this pool is regulated. Under nitrate-replete conditions vacuolar nitrate is a membrane-bound store that can release nitrate to the cytoplasm; after depletion of cytosolic nitrate, tonoplast transporters would serve to restore this pool. To study the role of assimilation, specifically the activity of NR in regulating the size of the cytosolic nitrate pool, we have compared wild-type and mutant plants. In leaf mesophyll cells, light-to-dark transitions increase cytosolic nitrate activity (1.5–2.8 mm), and these changes were reversed by dark-to-light transitions. Such changes were not observed in nia1nia2 NR-deficient plants indicating that this change in cytosolic nitrate activity was dependent on the presence of functional NR. Furthermore, in the dark, the steady-state cytosolic nitrate activities were not statistically different between the two types of plant, indicating that NR has little role in determining resting levels of nitrate. Epidermal cells of both wild type and NR mutants had cytosolic nitrate activities that were not significantly different from mesophyll cells in the dark and were unaltered by dark-to-light transitions. We propose that the NR-dependent changes in cytosolic nitrate provide a cellular mechanism for the diurnal changes in vacuolar nitrate storage, and the results are discussed in terms of the possible signaling role of cytosolic nitrate. PMID:15908593

[Effect of total hypothermia on the fatty acid composition of blood phospholipids of rats and sousliks and light irradiation on chemical processes in lipid extract].

PubMed

Zabelinskiĭ, S A; Chebotareva, M A; Kalandarov, A M; Feĭzulaev, B A; Klichkhanov, N K; Krivchenko, A I; Kazennov, A M

2011-01-01

Effect of hypothermia on the fatty acid composition of rat and souslik blood phospholipids is studied. Different reaction of these animals to cooling is revealed: in rats no changes were observed in the fatty acid composition of blood phospholipids, whereas in the hibernating there were significant changes in the content of individual fatty acids (FA). The content of monoenic acids in sousliks decreased almost by 50%, while the content of saturated acid (C18) and of polyenic acids C18 : 2omega6 and C20 : 4omega6 rose significantly. Such changes seem to be the mechanism that promotes maintenance of the organism viability under conditions of a decreased level of metabolism, heart rhythm, and body temperature and is evolutionarily acquired. At the same time, the observed changes in the content of individual FA do not lead to sharp changes in such integrative parameters as the total non-saturation of phospholipids, which determines liquid properties of chylomicrons and other lipolipoprotein transport particles of the souslik blood. There are studied absorption spectra of blood lipid extracts of rats and sousliks under effect of light as well as effect of light upon the FA composition of lipid extracts of these animals. The FA composition of lipid extracts has been established to remain practically constant, whereas the character of changes of spectra under action of light indicates the presence in the extracts of oxidation-reduction reactions. The obtained data allow suggesting that in the lipid extract there occurs cooperation both of the phospholipid molecules themselves and of them with other organic molecules, which makes it possible for fatty acids to participate in processes of transport both of electrons and of protons. This novel role of FA as a participant of the electron transfer might probably be extrapolated to chemical reactions (processes) occurring inside the membrane.

Distribution and Variation of Indole Glucosinolates in Woad (Isatis tinctoria L.) 1

PubMed Central

Elliott, Malcolm C.; Stowe, Bruce B.

1971-01-01

The exceptionally high levels in woad (Isatis tinctoria L.) of three indolic goitrogens, namely glucobrassicin, neoglucobrassicin, and glucobrassicin-1-sulfonate, permit the facile study of their distribution in the plant and their changes during its development. Woad seeds contain as much as 0.23% fresh weight of glucobrassicin but no other indole glucosinolate, while 1-week-old seedlings also contain substantial amounts of neoglucobrassicin and glucobrassicin-1-sulfonate in their shoots whether grown in the light or dark. The sulfonate is not found in roots, and light depresses neoglucobrassicin levels in shoots. Sterile root cultures synthesize glucobrassicin and neoglucobrassicin, and significant quantities of these were even found to be excreted by the roots of intact sterile seedlings in culture. This may explain the long known deleterious effect of woad and other cruciferous crops on subsequent plantings and the observation could be of ecological importance. Long term changes in levels of all three substances in the plant are similar and are compatible with earlier suggestions that the compounds could be auxin precursors at the time of flower stem elongation. Since sterile seedlings readily incorporate 35SO42− into indole glucosinolates and relative specific radioactivities suggest that glucobrassicin is the precursor of the other two compounds, pathways of goitrogen biosynthesis should be relatively easily determined in this material. PMID:16657825

Distribution and Variation of Indole Glucosinolates in Woad (Isatis tinctoria L.).

PubMed

Elliott, M C; Stowe, B B

1971-10-01

The exceptionally high levels in woad (Isatis tinctoria L.) of three indolic goitrogens, namely glucobrassicin, neoglucobrassicin, and glucobrassicin-1-sulfonate, permit the facile study of their distribution in the plant and their changes during its development. Woad seeds contain as much as 0.23% fresh weight of glucobrassicin but no other indole glucosinolate, while 1-week-old seedlings also contain substantial amounts of neoglucobrassicin and glucobrassicin-1-sulfonate in their shoots whether grown in the light or dark. The sulfonate is not found in roots, and light depresses neoglucobrassicin levels in shoots. Sterile root cultures synthesize glucobrassicin and neoglucobrassicin, and significant quantities of these were even found to be excreted by the roots of intact sterile seedlings in culture. This may explain the long known deleterious effect of woad and other cruciferous crops on subsequent plantings and the observation could be of ecological importance. Long term changes in levels of all three substances in the plant are similar and are compatible with earlier suggestions that the compounds could be auxin precursors at the time of flower stem elongation. Since sterile seedlings readily incorporate (35)SO(4) (2-) into indole glucosinolates and relative specific radioactivities suggest that glucobrassicin is the precursor of the other two compounds, pathways of goitrogen biosynthesis should be relatively easily determined in this material.

Combined effects of high hydrostatic pressure and sodium nitrite on color, water holding capacity and texture of frankfurter

NASA Astrophysics Data System (ADS)

Jonas, G.; Csehi, B.; Palotas, P.; Toth, A.; Kenesei, Gy; Pasztor-Huszar, K.; Friedrich, L.

2017-10-01

The aim of this study was to investigate the effect of sodium nitrite and high hydrostatic pressure on the color, water holding capacity (WHC) and texture characteristics of frankfurter. Three hundred, 450 and 600 MPa (5 minutes; 20 °C) and 50, 75, 100 and 125 ppm (calculated on weight of meat) sodium nitrite were applied. Parameters were measured right after the pressure treatment. Data were evaluated with two-way analysis of variance (p 0.05) with pressure levels and sodium nitrite amounts as factors. Nitrite reduction significantly increased lightness (L*) and resulted in decreased redness (a*) value. The pressure treatments decreased the lightness at all nitrite concentrations and did not significantly affect the red color of frankfurters. Fifty and 75 ppm nitrite and pressurization at 300 or 450 MPa improved the water holding property of frankfurter. The pressure treatment did not significantly affect the WHC but changing the nitrite amount had significant effect on it. Interactive effect occurred between pressure levels and nitrite concentrations for hardness. The pressure treatment increased and the nitrite reduction decreased hardness. Significant changes were found in cohesiveness at 450 and 600 MPa in frankfurters containing 50 and 75 ppm nitrite: pressure treatment at higher levels and nitrite reduction decreased the value of cohesiveness.

[Light-dependent changes in the enzyme activity of the ascorbate-glutathione cycle and ascorbate oxidase in the leaves of pea].

PubMed

Mittova, V O; Igamberdiev, A U

2000-01-01

Light-determined activation of ferments of ascorbate-glutation cycle, ascorbate-oxidase in chloroplasts and cytosol is demonstrated as well as ascorbate-peroxidase, monodehydroascorbate-reductase, glutation-reductase and ascorbate-oxydase in mitochondria. On the other hands activity of mitochondrial dehydroascorbate-reductase increased on reduction of light most likely due to function of electron transport from glutation to dehydroascorbate in mitochondria. Glutation metabolism is proved to be endogenic catalytic process where the amount reconstructed glutation changes slowly with a delay and gradually follow light changes. Light dependable changes of glutation content in chloroplasts ensure resistance of ferment system again hydrogen peroxide and superoxide radicals that generate intensively at light.

Using NIR spatial illumination for detection and mapping chromophore changes during cerebral edema

NASA Astrophysics Data System (ADS)

Abookasis, David; Mathews, Marlon S.; Owen, Christopher M.; Binder, Devin K.; Linskey, Mark E.; Frostig, Ron D.; Tromberg, Bruce J.

2008-02-01

We used spatially modulated near-infrared (NIR) light to detect and map chromophore changes during cerebral edema in the rat neocortex. Cerebral edema was induced by intraperitoneal injections of free water (35% of body weight). Intracranial pressure (ICP) was measured with an optical fiber based Fabry-Perot interferometer sensor inserted into the parenchyma of the right frontal lobe during water administration. Increase in ICP from a baseline value of 10 cm-water to 145 cm-water was observed. Following induction of cerebral edema, there was a 26+/-1.7% increase in tissue concentration of deoxyhemoglobin and a 47+/-4.7%, 17+/-3% and 37+/-3.7% decrease in oxyhemoglobin, total hemoglobin concentration and cerebral tissue oxygen saturation levels, respectively. To the best of our knowledge, this is the first report describing the use of NIR spatial modulation of light for detecting and mapping changes in tissue concentrations of physiologic chromophores over time in response to cerebral edema.

The MOST Accurate Photometry for Cepheid Modes

NASA Astrophysics Data System (ADS)

Evans, Nancy Remage; Szabo, Robert; Szabados, Laszlo; Derekas, Aliz; Kiss, Laszlo; Matthews, Jaymie; Cameron, Chris

2014-06-01

Fundamental mode classical Cepheids have famously repeatable light curves and periods steady enough that we can watch them evolve (change period). Overtone pulsators, on theother hand often have period changes too large to be explained by evolution, at least during the longest (second and third) passages through the instability strip. We obtained a month long series of observations with the MOST satellite of the fundamental mode Cepheid RT Aur and the first overtone pulsator SZ Tau. RT Aur shows the traditional strict repetition of the light curve, with the Fourier amplitude ratio R1/R2 remaining constant (varying by only a percent). The light curve of SZ Tau, on the other hand, fluctuates in amplitude ratio at the level of approximately 50\\%. Furthermore prewhitening the RT Aur data with 10 frequencies reduces the Fourier spectrum to noise. For SZ Tau, considerable power is left after this prewhitening in a complicated variety of frequencies. Financial Support was provided by CXC NASA Contract NAS8-03060 (NRE), ESTEC Contract No. 4000106398/12/NL/KML (LS), European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement No. 269194(IRSES/ASK) (RS, AD).

An Ocean Acidification Acclimatised Green Tide Alga Is Robust to Changes of Seawater Carbon Chemistry but Vulnerable to Light Stress

PubMed Central

Li, Xinshu; Feng, Zhihua; Xu, Juntian

2016-01-01

Ulva is the dominant genus in the green tide events and is considered to have efficient CO2 concentrating mechanisms (CCMs). However, little is understood regarding the impacts of ocean acidification on the CCMs of Ulva and the consequences of thalli’s acclimation to ocean acidification in terms of responding to environmental factors. Here, we grew a cosmopolitan green alga, Ulva linza at ambient (LC) and elevated (HC) CO2 levels and investigated the alteration of CCMs in U. linza grown at HC and its responses to the changed seawater carbon chemistry and light intensity. The inhibitors experiment for photosynthetic inorganic carbon utilization demonstrated that acidic compartments, extracellular carbonic anhydrase (CA) and intracellular CA worked together in the thalli grown at LC and the acquisition of exogenous carbon source in the thalli could be attributed to the collaboration of acidic compartments and extracellular CA. Contrastingly, when U. linza was grown at HC, extracellular CA was completely inhibited, acidic compartments and intracellular CA were also down-regulated to different extents and thus the acquisition of exogenous carbon source solely relied on acidic compartments. The down-regulated CCMs in U. linza did not affect its responses to changes of seawater carbon chemistry but led to a decrease of net photosynthetic rate when thalli were exposed to increased light intensity. This decrease could be attributed to photodamage caused by the combination of the saved energy due to the down-regulated CCMs and high light intensity. Our findings suggest future ocean acidification might impose depressing effects on green tide events when combined with increased light exposure. PMID:28033367

An Ocean Acidification Acclimatised Green Tide Alga Is Robust to Changes of Seawater Carbon Chemistry but Vulnerable to Light Stress.

PubMed

Gao, Guang; Liu, Yameng; Li, Xinshu; Feng, Zhihua; Xu, Juntian

2016-01-01

Ulva is the dominant genus in the green tide events and is considered to have efficient CO2 concentrating mechanisms (CCMs). However, little is understood regarding the impacts of ocean acidification on the CCMs of Ulva and the consequences of thalli's acclimation to ocean acidification in terms of responding to environmental factors. Here, we grew a cosmopolitan green alga, Ulva linza at ambient (LC) and elevated (HC) CO2 levels and investigated the alteration of CCMs in U. linza grown at HC and its responses to the changed seawater carbon chemistry and light intensity. The inhibitors experiment for photosynthetic inorganic carbon utilization demonstrated that acidic compartments, extracellular carbonic anhydrase (CA) and intracellular CA worked together in the thalli grown at LC and the acquisition of exogenous carbon source in the thalli could be attributed to the collaboration of acidic compartments and extracellular CA. Contrastingly, when U. linza was grown at HC, extracellular CA was completely inhibited, acidic compartments and intracellular CA were also down-regulated to different extents and thus the acquisition of exogenous carbon source solely relied on acidic compartments. The down-regulated CCMs in U. linza did not affect its responses to changes of seawater carbon chemistry but led to a decrease of net photosynthetic rate when thalli were exposed to increased light intensity. This decrease could be attributed to photodamage caused by the combination of the saved energy due to the down-regulated CCMs and high light intensity. Our findings suggest future ocean acidification might impose depressing effects on green tide events when combined with increased light exposure.

Drug-induced sleep endoscopy with target-controlled infusion using propofol and monitored depth of sedation to determine treatment strategies in obstructive sleep apnea.

PubMed

Heiser, Clemens; Fthenakis, Phillippe; Hapfelmeier, Alexander; Berger, Sebastian; Hofauer, Benedikt; Hohenhorst, Winfried; Kochs, Eberhard F; Wagner, Klaus J; Edenharter, Guenther M

2017-09-01

Drug-induced sleep endoscopy (DISE) has become an important diagnostic examination tool in the treatment decision process for surgical therapies in the treatment of obstructive sleep apnea (OSA). Currently, there is a variety of regimes for the performance of DISE, which renders comparison and assessment across results difficult. It remains unclear how the different regimes influence the findings of the examination and the resulting conclusions and treatment recommendations. This study aimed to investigate the correlation between increasing levels of sedation (i.e., light, medium, and deep) induced by propofol using a target-controlled infusion (TCI) pump, with the obstruction patterns at the levels of the velum, oropharynx, tongue base, and epiglottis (i.e., VOTE classification). A second goal was the establishment of a sufficient sedation level to enable a reliable decision regarding treatment recommendations. Forty-three patients with OSA underwent a DISE procedure using propofol TCI. Three levels of sedation were defined, depending on entropy levels and assessment of sedation: light sedation, medium sedation, and deep sedation. The evaluation of the upper airway at each level, with increasing sedation, was documented using the VOTE classification. The elapsed time at which each assessment was performed was recorded. Upper airway changes occurred and were measured throughout the DISE procedure. Clinically useful determinations of airway closure occurred at medium sedation; this level of sedation was most probably achieved with a blood propofol concentration of 3.2 μg/ml. In all 43 patients, definite treatment decisions could be made at medium sedation level. Increasing sedation did not result in changes in the treatment decision. Changes in upper airway collapse during DISE with propofol TCI occur at levels of medium sedation. Decisions regarding surgical treatment could be made at this level of sedation. Upper Airway Collapse in Patients with Obstructive Sleep Apnea Syndrome by Drug Induced Sleep Endoscopy (URL: https://clinicaltrials.gov/ct2/results?term=NCT02588300&Search=Search ) REGISTRATION NUMBER: NCT02588300.

A comparison of the light-reduction capacity of commonly used incubator covers.

PubMed

Lee, Yi-Hui; Malakooti, Nima; Lotas, Marilyn

2005-01-01

The use of incubator covers to enhance preterm infants' rest and recovery is common in the NICU. However, the kinds of covers used vary extensively among and within nurseries. Few data exist on the effectiveness of different types of covers in reducing light levels to the infant. This study compared several types of commonly used incubator covers as to efficacy of light reduction. A descriptive, comparative design was used in this study. Twenty-three incubator covers were tested, including professional, receiving blanket, hand-crocheted, three-layer quilt, and flannel. The percentage of light level reduction of different incubator covers under various ambient light level settings. The amount of light reduction provided by incubator covers varies depending on type of fabric as well as percentage of incubator surface shielded by the cover. Dark-colored covers provided greater light reduction than bright/light-colored covers when covers identical in fabric type were compared. The light-reduction efficiency of the covers varied depending on the level of ambient light. Covers provided less light reduction in higher ambient light levels.

Laser barometer

DOEpatents

Abercrombie, Kevin R.; Shiels, David; Rash, Tim

2001-02-06

A pressure measuring instrument that utilizes the change of the refractive index of a gas as a function of pressure and the coherent nature of a laser light to determine the barometric pressure within an environment. As the gas pressure in a closed environment varies, the index of refraction of the gas changes. The amount of change is a function of the gas pressure. By illuminating the gas with a laser light source, causing the wavelength of the light to change, pressure can be quantified by measuring the shift in fringes (alternating light and dark bands produced when coherent light is mixed) in an interferometer.

Rapid changes in protein phosphorylation associated with light-induced gravity perception in corn roots

NASA Technical Reports Server (NTRS)

McFadden, J. J.; Poovaiah, B. W.

1988-01-01

The effect of light and calcium depletion on in vivo protein phosphorylation was tested using dark-grown roots of Merit corn. Light caused rapid and specific promotion of phosphorylation of three polypeptides. Pretreatment of roots with ethylene glycol bis N,N,N',N' tetraacetic acid and A23187 prevented light-induced changes in protein phosphorylation. We postulate that these changes in protein phosphorylation are involved in the light-induced gravity response.

Evolution of optical force on two-level atom by ultrashort time-domain dark hollow Gaussian pulse

NASA Astrophysics Data System (ADS)

Cao, Xiaochao; Wang, Zhaoying; Lin, Qiang

2017-09-01

Based on the analytical expression of the ultrashort time-domain dark hollow Gaussian (TDHG) pulse, the optical force on two-level atoms induced by a TDHG pulse is calculated in this paper. The phenomena of focusing or defocusing of the light force is numerical analyzed for different detuning, various duration time, and different order of the ultrashort pulse. The transverse optical force can change from a focusing force to a defocusing force depending on the spatial-temporal coupling effect as the TDHG pulses propagating in free space. Our results also show that the initial phase of the TDHG pulse can significantly changes the envelope of the optical force.

Quantitative Assessment of Ultrastructure and Light Scatter in Mouse Corneal Debridement Wounds

PubMed Central

Boote, Craig; Du, Yiqin; Morgan, Sian; Harris, Jonathan; Kamma-Lorger, Christina S.; Hayes, Sally; Lathrop, Kira L.; Roh, Danny S.; Burrow, Michael K.; Hiller, Jennifer; Terrill, Nicholas J.; Funderburgh, James L.; Meek, Keith M.

2012-01-01

Purpose. The mouse has become an important wound healing model with which to study corneal fibrosis, a frequent complication of refractive surgery. The aim of the current study was to quantify changes in stromal ultrastructure and light scatter that characterize fibrosis in mouse corneal debridement wounds. Methods. Epithelial debridement wounds, with and without removal of basement membrane, were produced in C57BL/6 mice. Corneal opacity was measured using optical coherence tomography, and collagen diameter and matrix order were quantified by x-ray scattering. Electron microscopy was used to visualize proteoglycans. Quantitative PCR (Q-PCR) measured mRNA transcript levels for several quiescent and fibrotic markers. Results. Epithelial debridement without basement membrane disruption produced a significant increase in matrix disorder at 8 weeks, but minimal corneal opacity. In contrast, basement membrane penetration led to increases in light scatter, matrix disorder, and collagen diameter, accompanied by the appearance of abnormally large proteoglycans in the subepithelial stroma. This group also demonstrated upregulation of several quiescent and fibrotic markers 2 to 4 weeks after wounding. Conclusions. Fibrotic corneal wound healing in mice involves extensive changes to collagen and proteoglycan ultrastructure, consistent with deposition of opaque scar tissue. Epithelial basement membrane penetration is a deciding factor determining the degree of ultrastructural changes and resulting opacity. PMID:22467580

Single-molecule spectroscopy reveals photosynthetic LH2 complexes switch between emissive states

PubMed Central

Schlau-Cohen, Gabriela S.; Wang, Quan; Southall, June; Cogdell, Richard J.; Moerner, W. E.

2013-01-01

Photosynthetic organisms flourish under low light intensities by converting photoenergy to chemical energy with near unity quantum efficiency and under high light intensities by safely dissipating excess photoenergy and deleterious photoproducts. The molecular mechanisms balancing these two functions remain incompletely described. One critical barrier to characterizing the mechanisms responsible for these processes is that they occur within proteins whose excited-state properties vary drastically among individual proteins and even within a single protein over time. In ensemble measurements, these excited-state properties appear only as the average value. To overcome this averaging, we investigate the purple bacterial antenna protein light harvesting complex 2 (LH2) from Rhodopseudomonas acidophila at the single-protein level. We use a room-temperature, single-molecule technique, the anti-Brownian electrokinetic trap, to study LH2 in a solution-phase (nonperturbative) environment. By performing simultaneous measurements of fluorescence intensity, lifetime, and spectra of single LH2 complexes, we identify three distinct states and observe transitions occurring among them on a timescale of seconds. Our results reveal that LH2 complexes undergo photoactivated switching to a quenched state, likely by a conformational change, and thermally revert to the ground state. This is a previously unobserved, reversible quenching pathway, and is one mechanism through which photosynthetic organisms can adapt to changes in light intensities. PMID:23776245

Single-molecule spectroscopy reveals photosynthetic LH2 complexes switch between emissive states.

PubMed

Schlau-Cohen, Gabriela S; Wang, Quan; Southall, June; Cogdell, Richard J; Moerner, W E

2013-07-02

Photosynthetic organisms flourish under low light intensities by converting photoenergy to chemical energy with near unity quantum efficiency and under high light intensities by safely dissipating excess photoenergy and deleterious photoproducts. The molecular mechanisms balancing these two functions remain incompletely described. One critical barrier to characterizing the mechanisms responsible for these processes is that they occur within proteins whose excited-state properties vary drastically among individual proteins and even within a single protein over time. In ensemble measurements, these excited-state properties appear only as the average value. To overcome this averaging, we investigate the purple bacterial antenna protein light harvesting complex 2 (LH2) from Rhodopseudomonas acidophila at the single-protein level. We use a room-temperature, single-molecule technique, the anti-Brownian electrokinetic trap, to study LH2 in a solution-phase (nonperturbative) environment. By performing simultaneous measurements of fluorescence intensity, lifetime, and spectra of single LH2 complexes, we identify three distinct states and observe transitions occurring among them on a timescale of seconds. Our results reveal that LH2 complexes undergo photoactivated switching to a quenched state, likely by a conformational change, and thermally revert to the ground state. This is a previously unobserved, reversible quenching pathway, and is one mechanism through which photosynthetic organisms can adapt to changes in light intensities.

Responses of the photosynthetic electron transport system to excess light energy caused by water deficit in wild watermelon.

PubMed

Sanda, Satoko; Yoshida, Kazuo; Kuwano, Masayoshi; Kawamura, Tadayuki; Munekage, Yuri Nakajima; Akashi, Kinya; Yokota, Akiho

2011-07-01

In plants, drought stress coupled with high levels of illumination causes not only dehydration of tissues, but also oxidative damage resulting from excess absorbed light energy. In this study, we analyzed the regulation of electron transport under drought/high-light stress conditions in wild watermelon, a xerophyte that shows strong resistance to this type of stress. Under drought/high-light conditions that completely suppressed CO(2) fixation, the linear electron flow was diminished between photosystem (PS) II and PS I, there was no photoinhibitory damage to PS II and PS I and no decrease in the abundance of the two PSs. Proteome analyses revealed changes in the abundance of protein spots representing the Rieske-type iron-sulfur protein (ISP) and I and K subunits of NAD(P)H dehydrogenase in response to drought stress. Two-dimensional electrophoresis and immunoblot analyses revealed new ISP protein spots with more acidic isoelectric points in plants under drought stress. Our findings suggest that the modified ISPs depress the linear electron transport activity under stress conditions to protect PS I from photoinhibition. The qualitative changes in photosynthetic proteins may switch the photosynthetic electron transport from normal photosynthesis mode to stress-tolerance mode. Copyright © Physiologia Plantarum 2011.

Chemical cues from fish heighten visual sensitivity in larval crabs through changes in photoreceptor structure and function.

PubMed

Charpentier, Corie L; Cohen, Jonathan H

2015-11-01

Several predator avoidance strategies in zooplankton rely on the use of light to control vertical position in the water column. Although light is the primary cue for such photobehavior, predator chemical cues or kairomones increase swimming responses to light. We currently lack a mechanistic understanding for how zooplankton integrate visual and chemical cues to mediate phenotypic plasticity in defensive photobehavior. In marine systems, kairomones are thought to be amino sugar degradation products of fish body mucus. Here, we demonstrate that increasing concentrations of fish kairomones heightened sensitivity of light-mediated swimming behavior for two larval crab species (Rhithropanopeus harrisii and Hemigrapsus sanguineus). Consistent with these behavioral results, we report increased visual sensitivity at the retinal level in larval crab eyes directly following acute (1-3 h) kairomone exposure, as evidenced electrophysiologically from V-log I curves and morphologically from wider, shorter rhabdoms. The observed increases in visual sensitivity do not correspond with a decline in temporal resolution, because latency in electrophysiological responses actually increased after kairomone exposure. Collectively, these data suggest that phenotypic plasticity in larval crab photobehavior is achieved, at least in part, through rapid changes in photoreceptor structure and function. © 2015. Published by The Company of Biologists Ltd.

Color and illuminance level of lighting can modulate willingness to eat bell peppers.

PubMed

Hasenbeck, Aimee; Cho, Sungeun; Meullenet, Jean-François; Tokar, Tonya; Yang, Famous; Huddleston, Elizabeth A; Seo, Han-Seok

2014-08-01

Food products are often encountered under colored lighting, particularly in restaurants and retail stores. However, relatively little attention has been paid to whether the color of ambient lighting can affect consumers' motivation for consumption. This study aimed to determine whether color (Experiment 1) and illuminance level (Experiment 2) of lighting can influence consumers' liking of appearance and their willingness to eat bell peppers. For red, green, and yellow bell peppers, yellow and blue lighting conditions consistently increased participants' liking of appearance the most and the least, respectively. Participants' willingness to consume bell peppers increased the most under yellow lighting and the least under blue lighting. In addition, a dark condition (i.e. low level of lighting illuminance) decreased liking of appearance and willingness to eat the bell peppers compared to a bright condition (i.e. high level of lighting illuminance). Our findings demonstrate that lighting color and illuminance level can influence consumers' hedonic impression and likelihood to consume bell peppers. Furthermore, the influences of color and illuminance level of lighting appear to be dependent on the surface color of bell peppers. © 2013 Society of Chemical Industry.

Blue Light Protects Against Temporal Frequency Sensitive Refractive Changes.

PubMed

Rucker, Frances; Britton, Stephanie; Spatcher, Molly; Hanowsky, Stephan

2015-09-01

Time spent outdoors is protective against myopia. The outdoors allows exposure to short-wavelength (blue light) rich sunlight, while indoor illuminants can be deficient at short-wavelengths. In the current experiment, we investigate the role of blue light, and temporal sensitivity, in the emmetropization response. Five-day-old chicks were exposed to sinusoidal luminance modulation of white light (with blue; N = 82) or yellow light (without blue; N = 83) at 80% contrast, at one of six temporal frequencies: 0, 0.2, 1, 2, 5, 10 Hz daily for 3 days. Mean illumination was 680 lux. Changes in ocular components and corneal curvature were measured. Refraction, eye length, and choroidal changes were dependent on the presence of blue light (P < 0.03, all) and on temporal frequency (P < 0.03, all). In the presence of blue light, refraction did not change across frequencies (mean change -0.24 [diopters] D), while in the absence of blue light, we observed a hyperopic shift (>1 D) at high frequencies, and a myopic shift (>-0.6 D) at low frequencies. With blue light there was little difference in eye growth across frequencies (77 μm), while in the absence of blue light, eyes grew more at low temporal frequencies and less at high temporal frequencies (10 vs. 0.2 Hz: 145 μm; P < 0.003). Overall, neonatal astigmatism was reduced with blue light. Illuminants rich in blue light can protect against myopic eye growth when the eye is exposed to slow changes in luminance contrast as might occur with near work.

Blue Light Protects Against Temporal Frequency Sensitive Refractive Changes

PubMed Central

Rucker, Frances; Britton, Stephanie; Spatcher, Molly; Hanowsky, Stephan

2015-01-01

Purpose Time spent outdoors is protective against myopia. The outdoors allows exposure to short-wavelength (blue light) rich sunlight, while indoor illuminants can be deficient at short-wavelengths. In the current experiment, we investigate the role of blue light, and temporal sensitivity, in the emmetropization response. Methods Five-day-old chicks were exposed to sinusoidal luminance modulation of white light (with blue; N = 82) or yellow light (without blue; N = 83) at 80% contrast, at one of six temporal frequencies: 0, 0.2, 1, 2, 5, 10 Hz daily for 3 days. Mean illumination was 680 lux. Changes in ocular components and corneal curvature were measured. Results Refraction, eye length, and choroidal changes were dependent on the presence of blue light (P < 0.03, all) and on temporal frequency (P < 0.03, all). In the presence of blue light, refraction did not change across frequencies (mean change −0.24 [diopters] D), while in the absence of blue light, we observed a hyperopic shift (>1 D) at high frequencies, and a myopic shift (>−0.6 D) at low frequencies. With blue light there was little difference in eye growth across frequencies (77 μm), while in the absence of blue light, eyes grew more at low temporal frequencies and less at high temporal frequencies (10 vs. 0.2 Hz: 145 μm; P < 0.003). Overall, neonatal astigmatism was reduced with blue light. Conclusions Illuminants rich in blue light can protect against myopic eye growth when the eye is exposed to slow changes in luminance contrast as might occur with near work. PMID:26393671

Touch Sensor Responds to Contact Pressure

NASA Technical Reports Server (NTRS)

Bejczy, A. K.

1982-01-01

Optical tactile sensor for mechanical hands senses contact pressure via change in light reflected from an elastic covering. Pressure against a cell cover causes distortion, which changes internal reflection of light. Change is sensed by detector, and output signal informs operator of contact. The greater the pressure and distortion, the greater the change in light reflection.

Changes in alcohol consumption and subsequent risk of type 2 diabetes in men.

PubMed

Joosten, Michel M; Chiuve, Stephanie E; Mukamal, Kenneth J; Hu, Frank B; Hendriks, Henk F J; Rimm, Eric B

2011-01-01

The objective of this study was to investigate the association of 4-year changes in alcohol consumption with a subsequent risk of type 2 diabetes. We prospectively examined 38,031 men from the Health Professionals Follow-Up Study who were free of diagnosed diabetes or cancer in 1990. Alcohol consumption was reported on food frequency questionnaires and updated every 4 years. A total of 1,905 cases of type 2 diabetes occurred during 428,497 person-years of follow-up. A 7.5 g/day (approximately half a glass) increase in alcohol consumption over 4 years was associated with lower diabetes risk among initial nondrinkers (multivariable hazard ratio [HR] 0.78; 95% CI: 0.60-1.00) and drinkers initially consuming <15 g/day (HR 0.89; 95% CI: 0.83-0.96), but not among men initially drinking ≥15 g/day (HR 0.99; 95% CI: 0.95-1.02; P(interaction) < 0.01). A similar pattern was observed for levels of total adiponectin and hemoglobin A(1c), with a better metabolic profile among abstainers and light drinkers who modestly increased their alcohol intake, compared with men who either drank less or among men who were already moderate drinkers and increased their intake. Likewise, compared with stable light drinkers (0-4.9 g/day), light drinkers who increased their intake to moderate levels (5.0-29.9 g/day) had a significantly lower risk of type 2 diabetes (HR 0.75; 95% CI: 0.62-0.90). Increases in alcohol consumption over time were associated with lower risk of type 2 diabetes among initially rare and light drinkers. This lower risk was evident within a 4-year period following increased alcohol intake.

Spectral Sensitivity Change May Precede Habitat Shift in the Developing Retina of the Atlantic Tarpon (Megalops atlanticus).

PubMed

Schweikert, Lorian E; Grace, Michael S

Fish that undergo ontogenetic migrations between habitats often encounter new light environments that require changes in the spectral sensitivity of the retina. For many fish, sensitivity of the retina changes to match the environmental spectrum, but the timing of retinal change relative to habitat shift remains unknown. Does retinal change in fish precede habitat shift, or is it a response to encountered changes in environmental light? Spectral sensitivity changes were examined over the development of the Atlantic tarpon (Megalops atlanticus) retina relative to ontogenetic shifts in habitat light. Opsin gene isoform expression and inferred chromophore use of visual pigments were examined over the course of M. atlanticus development. Spectral sensitivity of the retina was then determined by electroretinography and compared to the spectroradiometric measurements of habitat light encountered by M. atlanticus from juveniles to adults. These data, along with previously known microspectrophotometric measurements of sensitivity in M. atlanticus, indicate retinal spectral sensitivity that matches the dominant wavelengths of environmental light for juvenile and adult fish. For the intervening subadult stage, however, spectral sensitivity does not match the dominant wavelength of light it occupies but better matches the dominant wavelengths of light in the habitat of its forthcoming migration. These results first indicate that the relationship between environmental light spectrum and spectral sensitivity of the retina changes during M. atlanticus development and then suggest that such changes may be programmed to support visual anticipation of new photic environments.

Pine Beetle Detection

NASA Technical Reports Server (NTRS)

1995-01-01

Earth Systems Science Office scientists worked with officials in St. Tammany Parish, La., to detect and battle pine beetle infestation in Fontainebleu State Park. The scientists used a new method of detecting plant stress by using special lenses and modified sensors to detect a change in light levels given off by the plant before the stress is visible to the naked eye.

Capturing Moment-To-Moment Changes in Multivariate Human Experience

ERIC Educational Resources Information Center

De Ruiter, Naomi M. P.; Van Der Steen, Steffie; Den Hartigh, Ruud J. R.; Van Geert, Paul L. C.

2017-01-01

In this article, we aim to shed light on a technique to study intra-individual variability that spans the time frame of seconds and minutes, i.e., micro-level development. This form of variability is omnipresent in behavioural development and processes of human experience, yet is often ignored in empirical studies, given a lack of proper analysis…

U. S. light duty vehicle fleet emissions performance and the emissions impact of technology changes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sabourin, M.; Platte, L

1988-01-01

This paper determines the level of improvement in Federal Test Procedure (FTP) exhaust emissions realized by typical in-use vehicles over the last twenty years as emission standards have become increasingly stringent. Furthermore, this paper explores the likelihood that in-use emission performance improvements will continue now that emission standards have stabilized.

Effects of Livestock Herd Migration on Child Schooling in Marsabit District, Kenya

ERIC Educational Resources Information Center

Mburu, Samuel

2017-01-01

To throw light on the challenge of providing education to pastoral households in the context of social and economic change, this study investigates the effects of herd migration on child schooling in Northern Kenya. Specifically, the analysis uses both household panel data and community-level focus-group data to identify the barriers to schooling,…

Photosynthetic functions of cembran pines and dwarf pines during winter at timberline as regulated by different temperatures, snowcover and light.

PubMed

Lehner, Gabriele; Lütz, Cornelius

2003-02-01

Trees at timberline in the high Alps are exposed to a variety of climatic conditions. Most climatic stresses occur during winter and spring, when frost, occasionally low snow cover, and high irradiation interact. In this study, we follow reactions of photosynthesis from high winter to spring in two dominating tree species of the alpine timberline, which may indicate the status of stress response to a changing environment. The results indicate a level of physiological stability in trees, which are important for stabilising natural high mountain ecosystems. Trees of Pinus cembra and of Pinus mugo were selected at altitudes between 1850 m a.s.l. and 1950 m a.s.l. near innsbruck, Austria. At six sampling times from January to May, fast chlorophyll fluorescence was measured in the field and twigs were collected for further investigation in the laboratory. The following measurements were taken: photosynthetic oxygen formation, needle chlorophyll and carotenoid determination, and kinetic studies of the xanthophyll cycle. In general, both tree species showed similar results in most parameters studied. P. mugo seems to have some advantages if winter precipitation is high, when, because of its growth habitus, most needles will be snow covered. Primary photochemistry (trapping per reaction centre) in PS II does not change with sampling dates despite the fact that temperature and light are changing. However, first events in electron transport and whole needle photosynthesis are strongly affected by light and temperature conditions during the days before sampling. The kinetics of the xanthophyll cycle indicate not only light, but also strong temperature effects. P. mugo photosynthesis seems to have a higher stability under changing weather. Both tree species are well prepared to start with photosynthesis in winter, if favourable conditions, like foehn events, occur.

Hypericin-mediated photocytotoxic effect on HT-29 adenocarcinoma cells is reduced by light fractionation with longer dark pause between two unequal light doses.

PubMed

Sacková, Veronika; Kuliková, Lucia; Mikes, Jaromír; Kleban, Ján; Fedorocko, Peter

2005-01-01

The present study demonstrates the in vitro effect of hypericin-mediated PDT with fractionated light delivery. Cells were photosensitized with unequal light fractions separated by dark intervals (1 or 6 h). We compared the changes in viability, cell number, survival, apoptosis and cell cycle on HT-29 cells irradiated with a single light dose (12 J/cm(2)) to the fractionated light delivery (1 + 11 J/cm(2)) 24 and 48 h after photodynamic treatment. We found that a fractionated light regime with a longer dark period resulted in a decrease of hypericin cytotoxicity. Both cell number and survival were higher after light sensitization with a 6-h dark interval. DNA fragmentation occurred after a single light-dose application, but in contrast no apoptotic DNA formation was detected with a 6-h dark pause. After fractionation the percentage of cells in the G1 phase of the cell cycle was increased, while the proportion of cells in the G2 phase decreased as compared to a single light-dose application, i.e. both percentage of cells in the G1 and G2 phase of the cell cycle were near control levels. We presume that the longer dark interval after the irradiation of cells by first light dose makes them resistant to the effect of the second illumination. These findings confirm that the light application scheme together with other photodynamic protocol components is crucial for the photocytotoxicity of hypericin.

SU-F-T-525: Monitordeep-Inspiratory Breathhold with a Laser Sensor for Radiation Therapy of Left Breast Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tai, A; Currey, A; Li, X Allen

2016-06-15

Purpose: Radiation therapy (RT) of left sided breast cancers with deep-inspiratory breathhold (DIBH) can reduce the dose to heart. The purpose of this study is to develop and test a new laser-based tool to improve ease of RT delivery using DIBH. Methods: A laser sensor together with breathing monitor device (Anzai Inc., Japan) was used to record the surface breathing motion of phantom/volunteers. The device projects a laser beam to the chestwall and the reflected light creates a focal spot on a light detecting element. The position change of the focal spot correlates with the patient’s breathing motion and ismore » measured through the change of current in the light detecting element. The signal is amplified and displayed on a computer screen, which is used to trigger radiation gating. The laser sensor can be easily mounted to the simulation/treatment couch with a fixing plate and a magnet base, and has a sensitivity range of 10 to 40 cm from the patient. The correlation of breathing signals detected by laser sensor and visionRT is also investigated. Results: It is found that the measured breathing signal from the laser sensor is stable and reproducible and has no noticeable delay. It correlates well with the VisionRT surface imaging system. The DIBH reference level does not change with movement of the couch because the laser sensor and couch move together. Conclusion: The Anzai laser sensor provides a cost-effective way to improve beam gating with DIBH for treating left breast cancer. It can be used alone or together with VisionRT to determine the correct DIBH level during the radiation treatment of left breast cancer with DIBH.« less

Identification of Early Nuclear Target Genes of Plastidial Redox Signals that Trigger the Long-Term Response of Arabidopsis to Light Quality Shifts.

PubMed

Dietzel, Lars; Gläßer, Christine; Liebers, Monique; Hiekel, Stefan; Courtois, Florence; Czarnecki, Olaf; Schlicke, Hagen; Zubo, Yan; Börner, Thomas; Mayer, Klaus; Grimm, Bernhard; Pfannschmidt, Thomas

2015-08-01

Natural illumination conditions are highly variable and because of their sessile life style, plants are forced to acclimate to them at the cellular and molecular level. Changes in light intensity or quality induce changes in the reduction/oxidation (redox) state of the photosynthetic electron chain that acts as a trigger for compensatory acclimation responses comprising functional and structural adjustments of photosynthesis and metabolism. Such responses include redox-controlled changes in plant gene expression in the nucleus and organelles. Here we describe a strategy for the identification of early redox-regulated genes (ERGs) in the nucleus of the model organism Arabidopsis thaliana that respond significantly 30 or 60 min after the generation of a reduction signal in the photosynthetic electron transport chain. By comparing the response of wild-type plants with that of the acclimation mutant stn7, we could specifically identify ERGs. The results reveal a significant impact of chloroplast redox signals on distinct nuclear gene groups including genes for the mitochondrial electron transport chain, tetrapyrrole biosynthesis, carbohydrate metabolism, and signaling lipid synthesis. These expression profiles are clearly different from those observed in response to the reduction of photosynthetic electron transport by high light treatments. Thus, the ERGs identified are unique to redox imbalances in photosynthetic electron transport and were then used for analyzing potential redox-responsive cis-elements, trans-factors, and chromosomal regulatory hot spots. The data identify a novel redox-responsive element and indicate extensive redox control at transcriptional and chromosomal levels that point to an unprecedented impact of redox signals on epigenetic processes. Copyright © 2015 The Author. Published by Elsevier Inc. All rights reserved.

Duration and intensity of shade differentially affects mycorrhizal growth- and phosphorus uptake responses of Medicago truncatula

PubMed Central

Konvalinková, Tereza; Püschel, David; Janoušková, Martina; Gryndler, Milan; Jansa, Jan

2015-01-01

Plant and fungal partners in arbuscular mycorrhizal symbiosis trade mineral nutrients for carbon, with the outcome of this relationship for plant growth and nutrition being highly context-dependent and changing with the availability of resources as well as with the specific requirements of the different partners. Here we studied how the model legume Medicago truncatula, inoculated or not with a mycorrhizal fungus Rhizophagus irregularis, responded to a gradient of light intensities applied over different periods of time, in terms of growth, phosphorus nutrition and the levels of root colonization by the mycorrhizal fungus. Short-term (6 d) shading, depending on its intensity, resulted in a rapid decline of phosphorus uptake to the shoots of mycorrhizal plants and simultaneous accumulation of phosphorus in the roots (most likely in the fungal tissues), as compared to the non-mycorrhizal controls. There was, however, no significant change in the levels of mycorrhizal colonization of roots due to short-term shading. Long-term (38 d) shading, depending on its intensity, provoked a multitude of plant compensatory mechanisms, which were further boosted by the mycorrhizal symbiosis. Mycorrhizal growth- and phosphorus uptake benefits, however, vanished at 10% of the full light intensity applied over a long-term. Levels of root colonization by the mycorrhizal fungus were significantly reduced by long-term shading. Our results indicate that even short periods of shade could have important consequences for the functioning of mycorrhizal symbiosis in terms of phosphorus transfer between the fungus and the plants, without any apparent changes in root colonization parameters or mycorrhizal growth response, and call for more focused research on temporal dynamics of mycorrhizal functioning under changing environmental conditions. PMID:25763002

Effect of tidal cycle and food intake on the baseline plasma corticosterone rhythm in intertidally foraging marine iguanas.

PubMed

Woodley, Sarah K; Painter, Danika L; Moore, Michael C; Wikelski, Martin; Romero, L Michael

2003-06-15

In most species, plasma levels of baseline glucocorticoids such as corticosterone (B) have a circadian rhythm. This rhythm can be entrained by both photoperiod and food intake and is related to aspects of energy intake and metabolism. Marine iguanas (Amblyrhynchus cristatus) offer a unique opportunity to better understand the relative importance of the light:dark cycle versus food intake in influencing the rhythm in baseline B in a natural system. Compared to other species, food intake is not as strictly determined by the phase of the light:dark cycle. Animals feed in the intertidal zone so feeding activity is heavily influenced by the tidal cycle. We measured baseline plasma B levels in free-living iguanas over several 24-h periods that varied in the timing of low tide/foraging activity. We found that baseline B levels were higher during the day relative to night. However, when low tide occurred during the day, baseline B levels dropped coincident with the timing of low tide. Whether the baseline B rhythm (including the drop during foraging) is an endogenous rhythm with a circatidal component, or is simply a result of feeding and associated physiological changes needs to be tested. Together, these data suggest that the baseline B rhythm in marine iguanas is influenced by the tidal cycle/food intake as well as the light:dark cycle.

Effects of B site doping on electronic structures of InNbO4 based on hybrid density functional calculations

NASA Astrophysics Data System (ADS)

Lu, M. F.; Zhou, C. P.; Li, Q. Q.; Zhang, C. L.; Shi, H. F.

2018-01-01

In order to improve the photocatalytic activity under visible-light irradiation, we adopted first principle calculations based on density functional theory (DFT) to calculate the electronic structures of B site transition metal element doped InNbO4. The results indicated that the complete hybridization of Nb 4d states and some Ti 3d states contributed to the new conduction band of Ti doped InNbO4, barely changing the position of band edge. For Cr doping, some localized Cr 3d states were introduced into the band gap. Nonetheless, the potential of localized levels was too positive to cause visible-light reaction. When it came to Cu doping, the band gap was almost same with that of InNbO4 as well as some localized Cu 3d states appeared above the top of VB. The introduction of localized energy levels benefited electrons to migrate from valence band (VB) to conduction band (CB) by absorbing lower energy photons, realizing visible-light response.

Auto-luminescent genetically encoded ratiometric indicator for real-time Ca2+ imaging at the single cell level

NASA Astrophysics Data System (ADS)

Saito, Kenta; Kobayashi, Kentaro; Nagai, Takeharu

2011-12-01

Efficient bioluminescence resonance energy transfer (BRET) from a bioluminescent protein to a fluorescent protein with high fluorescent quantum yield has been utilized to enhance luminescence intensity, allowing single-cell imaging in near real time without external light illumination. We have applied this strategy to develop an autoluminescent Ca2+ indicator, BRAC, which is composed of Ca2+-binding protein, calmodulin, and its target peptide, M13, sandwiched between a yellow fluorescent protein variant, Venus, and an enhanced Renilla luciferase, RLuc8. With this BRAC, we succeeded visualization of Ca2+ dynamics at the single-cell level with temporal resolution at 1 Hz. Moreover, BRAC signals were acquired by ratiometric imaging capable of canceling out Ca2+-independent signal drifts due to change in cell shape, focus shift, etc. Taking advantage of the bioluminescence imaging property that does not require external excitation light, BRAC might become a powerful tool applicable in conjunction with so-called optogenetic technology by which we can control cellular and protein function by light illumination.

Influence of light-induced conical intersection on the photodissociation dynamics of D2(+) starting from individual vibrational levels.

PubMed

Halász, Gábor J; Csehi, András; Vibók, Ágnes; Cederbaum, Lorenz S

2014-12-26

Previous works have shown that dressing of diatomic molecules by standing or by running laser waves gives rise to the appearance of so-called light-induced conical intersections (LICIs). Because of the strong nonadiabatic couplings, the existence of such LICIs may significantly change the dynamical properties of a molecular system. In our former paper (J. Phys. Chem. A 2013, 117, 8528), the photodissociation dynamics of the D(2)(+) molecule were studied in the LICI framework starting the initial vibrational nuclear wave packet from the superposition of all the vibrational states initially produced by ionizing D(2). The present work complements our previous investigation by letting the initial nuclear wave packets start from different individual vibrational levels of D(2)(+), in particular, above the energy of the LICI. The kinetic energy release spectra, the total dissociation probabilities, and the angular distributions of the photofragments are calculated and discussed. An interesting phenomenon has been found in the spectra of the photofragments. Applying the light-induced adiabatic picture supported by LICI, explanations are given for the unexpected structure of the spectra.