WorldWideScience

Sample records for ambient uv-b radiation

  1. Ambient UV-B radiation reduces PSII performance and net photosynthesis in high Arctic Salix arctica

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Ro-Poulsen, H.;

    2011-01-01

    Ambient ultraviolet-B (UV-B) radiation potentially impacts the photosynthetic performance of high Arctic plants. We conducted an UV-B exclusion experiment in a dwarf shrub heath in NE Greenland (74°N), with open control, filter control, UV-B filtering and UV-AB filtering, all in combination with ...... across position in the vegetation. These findings add to the evidence that the ambient solar UV-B currently is a significant stress factor for plants in high Arctic Greenland....

  2. Ambient UV-B radiation decreases photosynthesis in high arctic Vaccinium uliginosum

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Ro-Poulsen, H.

    2008-01-01

    ). Leaf area, biomass, carbon, nitrogen and UV-B-absorbing compounds were determined from a late season harvest. Compared with the reduced UV-B treatment, the plants in ambient UV-B were found to have a higher content of UV-B-absorbing compounds, and canopy net photosynthesis was as an average 23% lower...... during the season. By means of the JIP-test, it was found that the potential of processing light energy through the photosynthetic machinery was slightly reduced in ambient UV-B. This indicates that not only the UV-B effects on PSII may be responsible for some of the observed reduction of photosynthesis...... on photosynthesis clearly indicates that V. uliginosum is negatively affected by the current level of UV-B....

  3. Ameliorating effect of UV-B radiation on the response of Norway spruce and Scots pine to ambient ozone concentrations

    International Nuclear Information System (INIS)

    Elevated levels of both ozone and UV-B radiation are typical for high-altitude sites. Few studies have investigated their possible interaction on plants. This study reports interactive effects of O3 and UV-B radiation in four-year-old Norway spruce and Scots pine trees. The trees were cultivated in controlled environmental facilities under simulated climatic conditions recorded on Mt Wank, an Alpine mountain in Bavaria, and were exposed for one growing season to simulated ambient or twice-ambient ozone regimes at either near ambient or near zero UV-B radiation levels. Chlorotic mottling and yellowing of current year needles became obvious under twice-ambient O3 in both species at the onset of a high ozone episode in July. Development of chlorotic mottling in relation to accumulated ozone concentrations over a threshold of 40 nL L–1 was more pronounced with near zero rather than ambient UV-B radiation levels. In Norway spruce, photosynthetic parameters at ambient CO2 concentration, measured at the end of the experiment, were reduced in trees cultivated under twice-ambient O3, irrespective of the UV-B treatment. Effects on photosynthetic capacity and carboxylation efficiency were restricted to trees exposed to near zero levels of UV-B radiation, and twice-ambient O3. The data indicate that UV-B radiation, applied together with O3, ameliorates the detrimental effects of O3. The data also demonstrate that foliar symptoms develop more rapidly in Scots pine than in Norway spruce at higher accumulated ozone concentrations. (author)

  4. Ambient UV-B radiation reduces PSII performance and net photosynthesis in high Arctic Salix arctica

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Ro-Poulsen, Helge;

    2011-01-01

    with leaf angle control. Two sites with natural leaf positions had ground angles of 0° (‘level site’) and 45° (‘sloping site’), while at a third site the leaves were fixed in an angle of 45° to homogenize the irradiance dose (‘fixed leaf angle site’). The photosynthetic performance of the leaves...... was characterized by simultaneous gas exchange and chlorophyll fluorescence measurements and the PSII performance through the growing season was investigated with fluorescence measurements. Leaf harvest towards the end of the growing season was done to determine the specific leaf area and the content of carbon......, nitrogen and UV-B absorbing compounds. Compared to a 60% reduced UV-B irradiance, the ambient solar UV-B reduced net photosynthesis in Salix arctica leaves fixed in the 45° position which exposed leaves to maximum natural irradiance. Also a reduced Calvin Cycle capacity was found, i.e. the maximum rate...

  5. Effects of Reducing the Ambient UV-B Radiation in the High Arctic on Salix arctica and Vaccinium uliginosum

    DEFF Research Database (Denmark)

    Albert, Kristian; Ro-Poulsen, Helge; Mikkelsen, Teis Nørgaard;

    2005-01-01

    Effects of reducing the ambient UV-B radiation on gas exchange and chlorophyll fluores-cence of two dwarf shrub species, Salix arctica and Vaccinium uliginosum, was studied in a high arctic heath in North East Greenland during two growing seasons. Films (Mylar, transmitting ¿ > 320 nm, and Lexan...

  6. Effects of reducing the ambient UV-B radiation in the high Arctic on Salix arctica and Vaccinium uliginosum

    DEFF Research Database (Denmark)

    Albert, K.R.; Ro-Poulsen, H.; Mikkelsen, Teis Nørgaard;

    2005-01-01

    Effects of reducing the ambient UV-B radiation on gas exchange and chlorophyll fluores-cence of two dwarf shrub species, Salix arctica and Vaccinium uliginosum, was studied in a high arctic heath in North East Greenland during two growing seasons. Films (Mylar, transmitting λ > 320 nm, and Lexan,...

  7. Foraging behavior of honey bees (hymenoptera: Apidae) on Brassica nigra and B. rapa grown under simulated ambient and enhanced UV-B radiation

    International Nuclear Information System (INIS)

    Two species of mustard, Brassica nigra and B. rapa, were grown under simulated ambient and enhanced ultraviolet-B (UV-B) radiation and exposed to pollinators, Apis mellifera L. Observations were made to determine whether UV-B-induced changes in these plants affected pollinator behavior. Total duration of the foraging trip, number of flowers visited, foraging time per flower, search time per flower, total amount of pollen collected, and pollen collected per flower were measured. There were no significant differences between UV-B treatments in any of the behaviors measured or in any of the pollen measurements. These results suggest that increases in the amount of solar UV-B reaching the earth's surface may not have a negative effect on the relationship between these members of the genus Brassica and their honey bee pollinators. 28 refs., 2 figs., 1 tab

  8. Foraging behavior of honey bees (hymenoptera: Apidae) on Brassica nigra and B. rapa grown under simulated ambient and enhanced UV-B radiation

    Energy Technology Data Exchange (ETDEWEB)

    Collins, S.A.; Robinson, G.E. [Univ. of Illinois, Urbana, IL (United States); Conner, J.K. [Univ. of Illinois, Champaign, IL (United States)

    1997-01-01

    Two species of mustard, Brassica nigra and B. rapa, were grown under simulated ambient and enhanced ultraviolet-B (UV-B) radiation and exposed to pollinators, Apis mellifera L. Observations were made to determine whether UV-B-induced changes in these plants affected pollinator behavior. Total duration of the foraging trip, number of flowers visited, foraging time per flower, search time per flower, total amount of pollen collected, and pollen collected per flower were measured. There were no significant differences between UV-B treatments in any of the behaviors measured or in any of the pollen measurements. These results suggest that increases in the amount of solar UV-B reaching the earth`s surface may not have a negative effect on the relationship between these members of the genus Brassica and their honey bee pollinators. 28 refs., 2 figs., 1 tab.

  9. Effects of ambient versus reduced UV-B radiation on high arctic Salix arctica assessed by measurements and calculations of chlorophyll-a fluorescence parameters from fluorescence transients

    DEFF Research Database (Denmark)

    Albert, Kristian Rost

    2005-01-01

    received approximately 90 and 40% of the ambient UV-B irradiance, respectively. The effects were examined through recordings of chlorophyll a fluorescence transients, determination of biomass and analysis of total carbon and nitrogen content and amount of soluble flavonoids in the leaves. The processing...... of light was analysed by means of the chlorophyll a fluorescence transient, using the so-called JIP test, as evolved by Reto J. Strasser and his coworkers. Reduction of the UV-B irradiance caused a rise in many of the fluorescence parameters during July, but not in August (late season). Thus increases...... on fluorescence parameters that were directly measured (e.g. F0 and FM) and those that were derived (e.g. quantum efficiencies, parameters per PSII reaction centres and per cross-section of leaf sample) are discussed in relation to one another, in relation to daily and seasonal variation, and from the perspective...

  10. UV-B radiation and acclimation in timberline plants

    Energy Technology Data Exchange (ETDEWEB)

    Turunen, Minna [Arctic Centre, University of Lapland, PO Box 122, FI-96101 Rovaniemi (Finland)]. E-mail: minna.turunen@ulapland.fi; Latola, Kirsi [Thule Institute, PO Box 7300, FI-90014 University of Oulu, Oulu (Finland)

    2005-10-15

    Research has shown that some plants respond to enhanced UV-B radiation by producing smaller and thicker leaves, by increasing the thickness of epidermis and concentration of UV-B absorbing compounds of their surface layers and activation of the antioxidant defence system. The response of high-altitude plants to UV-B radiation in controlled conditions is often less pronounced compared to low-altitude plants, which shows that the alpine timberline plants are adapted to UV-B. These plants may have a simultaneous co-tolerance for several stress factors: acclimation or adaptation to the harsh climate can also increase tolerance to UV-B radiation, and vice versa. On the other hand, alpine timberline plants of northern latitudes may be less protected against increasing UV-B radiation than plants from more southern latitudes and higher elevations due to harsh conditions and weaker preadaptation resulting from lower UV-B radiation exposure. It is evident that more long-term experimental field research is needed in order to study the interaction of climate, soil and UV-B irradiance on the timberline plants. - More long-term field research is needed to assess the interaction of climate, soil and UV-B on timberline plants.

  11. UV-B Radiation Contributes to Amphibian Population Declines

    Science.gov (United States)

    Blaustein, Andrew

    2007-05-01

    UV-B (280-315 nm) radiation is the most significant biologically damaging radiation at the terrestrial surface. At the organismal level, UV-B radiation can slow growth rates, cause immune dysfunction and result in sublethal damage. UV-B radiation can lead to mutations and cell death. Over evolutionary time, UV radiation has been an important stressor on living organisms. Natural events, including impacts from comets and asteroids, volcanic activity, supernova explosions and solar flares, can cause large-scale ozone depletion with accompanying increases in UV radiation. However, these natural events are transient. Moreover, the amount of ozone damage due to natural events depends upon a number of variables, including the magnitude of the event. This is different from modern-day human-induced production of chlorofluorocarbons (CFCs) and other chemicals that deplete stratospheric ozone continuously, resulting in long-term increases in UV-B radiation at the surface of the earth. We will briefly review the effects of UV-B exposure in one group of aquatic organisms_amphibians. UV-B has been implicated as a possible factor contributing to global declines and range reductions in amphibian populations.

  12. Biological responses to current UV-B radiation in Arctic regions

    DEFF Research Database (Denmark)

    Albert, Kristian; N. Mikkelsen, Teis; Ro-Poulsen, Helge

    -B was demonstrated to decrease photosynthesis and shift carbon allocation from shoots to roots. Moreover, ambient UV-B increased plant stress with detrimental effects on electron processing in the photosynthetic apparatus. Plant responses did not lead to clear changes in the amount of fungal root symbionts...... on high-arctic vegetation. They supplement previous investigations from the Arctic focussing on other variables like growth etc., which have reported no or minor plant responses to UV-B, and clearly indicates that UV-B radiation is an important factor affecting plant life at high-arctic Zackenberg...

  13. Effect of enhanced UV-B radiation on motile microorganisms

    International Nuclear Information System (INIS)

    The effect of slightly increased UV-B radiation was studied in four taxonomically very different microorganisms: the gliding prokaryotic cyanobacterium, Phormidium, the unicellular green alga Cosmarium, the flagellate Euglena and the cellular slime mold Dictyostelium. UV-B doses which can be expected as a result of a slight decrease of the protective ozone layer in the stratosphere, do not kill or damage the microorganisms visibly. However, such UV-B doses impair the development, motility and photoorientation of these organisms. Due to the inhibition of these physiological important parameters the organisms cannot respond adequately to the changing factors in their environment, which prevents the survival of the populations. (orig.)

  14. Growth, photosynthesis and UV-B absorbing compounds of Portuguese Barbela wheat exposed to ultraviolet-B radiation

    International Nuclear Information System (INIS)

    Wheat plants (Triticum aestivum L.) were exposed to two levels of UV-B radiation (ambient UV-B and high UV-B, simulating a 20% reduction in the ozone layer) under mediterranean field-growth conditions. After 4 months of UV-B treatment, total plant biomass of high UV-B plants was 18% lower compared to control plants. The decrease of biomass appears to be the result of changes in morphological and physiological processes. High UV-B treatment induces decreases in leaf area, net photosynthesis rate, transpiration rate and water use efficiency. Pigment analysis of leaf extracts showed increases in chlorophyll content and no effect on accumulation of UV-B absorbing pigments. The underlying mechanisms for these results are discussed. (author)

  15. Effect of Ambient UV-B on Stomatal Density, Conductance and Isotope Discrimination in Four Field Grown Soybean [Glycine max (L.) Merr.] Isolines

    Science.gov (United States)

    Interactions between UV-B radiation and drought stress have been studied but the underlying mechanisms have not been thoroughly investigated. We hypothesized that ambient UV-B radiation would increase water use efficiency (WUE) through its effects on epidermal development, specifically reduced stoma...

  16. Effects of enhanced UV-B radiation on Mentha spicata essential oils

    International Nuclear Information System (INIS)

    In vitro propagated plantlets representing two distinct chemotypes of Mentha spicata, viz. plants producing essential oils rich in piperitone oxide and piperitenone oxide (chemotype I) and rich in carvone and dihydrocarvone (chemotype II), were grown in the field under ambient or ambient plus supplemental UV-B radiation, biologically equivalent to a 15% ozone depletion over Patras (38.3°N, 29.1°E), Greece. Enhanced UV-B radiation stimulated essential oil production in chemotype II substantially, while a similar, non-significant trend was observed in chemotype I. No effect was found on the qualitative composition of the essential oils, whereas the quantitative composition was slightly modified in chemotype I. This is the first investigation reporting an improved essential oil content under UV-B supplementation in aromatic plants under field conditions

  17. Experimental assessment of cumulative temperature and UV-B radiation effects on Mediterranean plankton metabolism

    KAUST Repository

    Garcia-Corral, Lara S.

    2015-07-07

    The Mediterranean Sea is a vulnerable region for climate change, warming at higher rates compare to the global ocean. Warming leads to increased stratification of the water column and enhanced the oligotrophic nature of the Mediterranean Sea. The oligotrophic waters are already highly transparent, however, exposure of Mediterranean plankton to ultraviolet radiation (UV-B and UV-A) may increase further if the waters become more oligotrophic, thereby, allowing a deeper UV radiation penetration and likely enhancing impacts to biota. Here we experimentally elucidate the cumulative effects of warming and natural UV-B radiation on the net community production (NCP) of plankton communities. We conducted five experiments at monthly intervals, from June to October 2013, and evaluated the responses of NCP to ambient UV-B radiation and warming (+3°C), alone and in combination, in a coastal area of the northwest Mediterranean Sea. UV-B radiation and warming lead to reduced NCP and resulted in a heterotrophic (NCP < 0) metabolic balance. Both UV-B radiation and temperature, showed a significant individual effect in NCP across treatments and time. However, their joint effect showed to be synergistic as the interaction between them (UV × Temp) was statistically significant in most of the experiments performed. Our results showed that both drivers, would affect the gas exchange of CO2−O2 from and to the atmosphere and the role of plankton communities in the Mediterranean carbon cycle.

  18. Experimental assessment of cumulative temperature and UV-B radiation effects on Mediterranean plankton metabolism

    Directory of Open Access Journals (Sweden)

    Lara S. eGarcia-Corral

    2015-07-01

    Full Text Available The Mediterranean Sea is a vulnerable region for climate change, warming at higher rates compare to the global ocean. Warming leads to increased stratification of the water column and enhanced the oligotrophic nature of the Mediterranean Sea. The oligotrophic waters are already highly transparent, however, exposure of Mediterranean plankton to ultraviolet radiation (UV-B and UV-A may increase further if the waters become more oligotrophic, thereby, allowing a deeper UV radiation penetration and likely enhancing impacts to biota.Here we experimentally elucidate the cumulative effects of warming and natural UV-B radiation on the net community production (NCP of plankton communities. We conducted five experiments at monthly intervals, from June to October 2013, and evaluated the responses of NCP to ambient UV-B radiation and warming (+3ºC, alone and in combination, in a coastal area of the northwest Mediterranean Sea. UV-B radiation and warming lead to reduced net community production and resulted in a heterotrophic (NCP<0 metabolic balance. Both UV-B radiation and temperature, showed a significant individual effect in NCP across treatments and time. However, their joint effect showed to be synergistic as the interaction between them (UV x Temp was statistically significant in most of the experiments performed. Our results showed that both drivers, would affect the gas exchange of CO2-O2 from and to the atmosphere and the role of plankton communities in the Mediterranean carbon cycle

  19. DNA repair and resistance to UV-B radiation in western spotted frogs

    Science.gov (United States)

    Blaustein, A.R.; Hays, J.B.; Hoffman, P.D.; Chivers, D.P.; Kiesecker, J.M.; Leonard, W.P.; Marco, A.; Olson, D.H.; Reaser, J.K.; Anthony, R.G.

    1999-01-01

    We assessed DNA repair and resistance to solar radiation in eggs of members of the western spotted frog complex (Rana pretiosa and R. luteiventris), species whose populations are suffering severe range reductions and declines. Specifically, we measured the activity of photoreactivating enzyme (photolyase) in oocytes of spotted frogs. In some species, photoreactivation is the most important mechanism for repair of UV-damaged DNA. Using field experiments, we also compared the hatching success of spotted frog embryos at natural oviposition sites at three elevations, where some embryos were subjected to ambient levels of UV-B radiation and others were shielded from UV-B radiation. Compared with other amphibians, photolyase activities in spotted frogs were relatively high. At all sites, hatching success was unaffected by UV-B. Our data support the interpretation that amphibian embryos with relatively high levels of photolyase are more resistant to UV-B radiation than those with lower levels of photolyase. At the embryonic stage, UV-B radiation does not presently seem to be contributing to the population declines of spotted frogs.

  20. Effect of enhanced UV-B radiation on pollen quantity, quality, and seed yield in Brassica rapa (Brassicaceae)

    International Nuclear Information System (INIS)

    Three experiments examined the influence of ultraviolet-B radiation (UV-B; 280-320 nm) exposure on reproduction in Brassica rapa (Brassicacaeae). Plants were grown in a greenhouse under three biologically effective UV-B levels that stimulated either an ambient stratospheric ozone level (control), 16% (open-quotes low enhancedclose quotes), or 32% (open-quotes high enhancedclose quotes) ozone depletion levels at Morgantown, WV, USA in mid-March. In the first experiment,pollen production and viability per flower were reduced by ∼50% under both enhanced UV-B levels relative to ambient controls. While plants under high-enhanced UV-B produced over 40% more flowers than plants under the two lower UV-B treatments, whole-plant production of viable pollen was reduced under low-enhanced UV-B to 34% of ambient controls. In the second experiment, the influence of source-plant UV-B exposure on in vitro pollen from plants was examined and whether source-plant UV-B exposure influenced in vitro pollen germination and viability. Pollen from plants under both enhanced-UV-B was reduced from 65 to 18%. Viability of the pollen from plants grown under both enhanced UV-B treatments was reduced to a much lesser extent: only from ∼43 to 22%. Thus, ambient source-plant pollen was more sensitive to enhanced UV-B levels to fertilize plants growing under ambient-UV-B levels, and assessed subsequent seed production and germination. Seed abortion rates were higher in plants pollinated with pollen from the enhanced UV-B treatments, than from ambient UV-B. Despite this, seed yield (number and mass) per plant was similar, regardless of the UV-B exposure of their pollen source. Our findings demonstrate that enhanced UV-B levels associated with springtime ozone depletion events have the capacity to substantially reduce viable pollen production, and could ultimately reduce reproductive success of B. rapa. 37 refs., 4 figs., 2 tabs

  1. Effect of enhanced UV-B radiation on pollen quantity, quality, and seed yield in Brassica rapa (Brassicaceae)

    Energy Technology Data Exchange (ETDEWEB)

    Demchik, S.M.; Day, T.A. [West Virginia Univ., Morgantown, WV (United States)

    1996-05-01

    Three experiments examined the influence of ultraviolet-B radiation (UV-B; 280-320 nm) exposure on reproduction in Brassica rapa (Brassicacaeae). Plants were grown in a greenhouse under three biologically effective UV-B levels that stimulated either an ambient stratospheric ozone level (control), 16% ({open_quotes}low enhanced{close_quotes}), or 32% ({open_quotes}high enhanced{close_quotes}) ozone depletion levels at Morgantown, WV, USA in mid-March. In the first experiment,pollen production and viability per flower were reduced by {approx}50% under both enhanced UV-B levels relative to ambient controls. While plants under high-enhanced UV-B produced over 40% more flowers than plants under the two lower UV-B treatments, whole-plant production of viable pollen was reduced under low-enhanced UV-B to 34% of ambient controls. In the second experiment, the influence of source-plant UV-B exposure on in vitro pollen from plants was examined and whether source-plant UV-B exposure influenced in vitro pollen germination and viability. Pollen from plants under both enhanced-UV-B was reduced from 65 to 18%. Viability of the pollen from plants grown under both enhanced UV-B treatments was reduced to a much lesser extent: only from {approx}43 to 22%. Thus, ambient source-plant pollen was more sensitive to enhanced UV-B levels to fertilize plants growing under ambient-UV-B levels, and assessed subsequent seed production and germination. Seed abortion rates were higher in plants pollinated with pollen from the enhanced UV-B treatments, than from ambient UV-B. Despite this, seed yield (number and mass) per plant was similar, regardless of the UV-B exposure of their pollen source. Our findings demonstrate that enhanced UV-B levels associated with springtime ozone depletion events have the capacity to substantially reduce viable pollen production, and could ultimately reduce reproductive success of B. rapa. 37 refs., 4 figs., 2 tabs.

  2. Long-term effects of elevated UV-B radiation on photosynthesis and ultrastructure of Eriophorum russeolum and Warnstorfia exannulata

    International Nuclear Information System (INIS)

    The depletion of stratospheric ozone above the Arctic regions may increase the amount of UV-B radiation to which the northern ecosystems are exposed. In this paper, we examine the hypothesis that supplemental UV-B radiation may affect the growth rate and photosynthesis of boreal peatland plants and could thereby affect the carbon uptake of these ecosystems. In this study, we report the effects of 3-year exposure to elevated UV-B radiation (46% above ambient) on the photosynthetic performance and ultrastructure of a boreal sedge Eriophorum russeolum and a moss Warnstorfia exannulata. The experiment was conducted on a natural fen ecosystem at Sodankylae in northern Finland. The effects of UV-B radiation on the light response of E. russeolum CO2 assimilation and the maximal photochemical efficiency of photosystem II in a dark-adapted state (Fv/Fm) were measured in the field. In addition, the effect of supplemental UV-B radiation on organelles of photosynthetic cells was studied by electron microscopy. The UV-B treatment had no effect on the CO2 assimilation rate of either species, nor did it affect the structure of the cell organelles. On chlorophyll fluorescence, the UV-B exposure had only a temporary effect during the third exposure year. Our results suggested that in a natural ecosystem, even long-term exposure to reasonably elevated UV-B radiation levels does not affect the photosynthesis of peatland plants. - Research highlights: →Eriophorum russeolum and Warnstorfia exannulata are resistant to UV-B radiationUV-B exposure does not affect the growth or photosynthesis of E. russeolum →Long-term UV-B exposure has no effect on the ultrastructure of E. russeolum

  3. Possible impacts of changes in UV-B radiation on North American trees and forests

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, Joe H. [Department of Natural Resource Sciences and Landscape Architecture, University of Maryland, College Park, MD (United States)]. E-mail: js128@umail.umd.edu

    2005-10-15

    Approximately 35 species representing 14 tree genera have been evaluated for responses to UV-B radiation in North America. The best representation has been in the conifers where some 20 species representing three genera have been studied. Overall, about 1/3 of these have demonstrated some deleterious response to UV-B. However, most negative impacts have been observed under controlled environment conditions where sensitivity may be enhanced. Therefore, it seems unlikely that expected levels of ozone depletion will result in direct losses in productivity. However, the role that ambient or enhanced levels of UV-B may play in forest ecosystem processes is more difficult to access. One possible indirect response of forests to changes in UV-B radiation levels could be via alterations in plant secondary metabolites. Increases in phenolics and flavonoids that enhance epidermal UV-screening effectiveness may also influence leaf development, water relations or ecosystem processes such as plant-herbivore interactions or decomposition. - Projected increases in UV-B are not likely to have a direct impact on trees, but indirect responses could impact plant-herbivore interactions and nutrient cycling in forests.

  4. Variations in Growth, Photosynthesis and Defense System Among Four Weed Species Under Increased UV-B Radiation

    Institute of Scientific and Technical Information of China (English)

    Shiwen Wang; Liusheng Duan; Anthony Egrinya Eneji; Zhaohu Li

    2007-01-01

    Weed tolerance of UV-B radiation varies with species, and the radiation could affect weed ecology and management.Variations in growth, photosynthesis and defense system among four important agronomic weeds, Abutilon theophrasti Medik, Amaranthus retroflexus L., Digitaria sangulnalis (L.) Scop and Chloris virgata Swartz, under increased UV-B radiation (ambient and increased radiation at 2.7, 5.4 and 10.8 kJ·m-2·d-1) were studied in the greenhouse experiment. After 2 weeks of radiation, the shoots' dry mass decreased with increasing UV-B radiation except for D. sanguinalis. The reduction in biomass was the result of changes in morphology and physiology.Higher levels of UV-B treatment decreased the leaf area, plant height, net photosynthetic rate and chlorophyll contents, while it increased the contents of wax and UV-B absorbing compound in all species, except for A. retroflexus,which did not increase significantly. The activity of superoxide dismutase, catalase, ascorbate peroxide and the content of ascorbic acid changed differently among the weed species as UV-B radiation increased. D. sanguinalis was the most tolerant and A. retroflexus the most sensitive to increased UV-B radiation. The results also show that the two grass species (D. sanguinalis and C. virgata) were more tolerant to UV-B radiation than the two broadleafed species (A. theophrasti and A. retroflexus). The UV-B absorbing compound and leaf wax played important roles against UV-B damages in the two grass weeds. The overall results suggest that weed community, competition and management will be altered by continuous ozone depletion.

  5. Influence of enhanced UV-B radiation on biomass allocation and pigment concentrations in leaves and reproductive structures of greenhouse-grown Brassica rapa

    International Nuclear Information System (INIS)

    We assessed the effects of enhanced ultraviolet-B radiation (UV-B; 280–320 nm) on biomass allocation to roots, shoots, leaves and flowers in the annual Brassica rapa. In addition, we investigated how concentrations of chlorophyll and UV-B-absorbing compounds in leaves, ovaries and pollen changed in response to enhanced UV-B. Plants were grown for 38 d in a greenhouse under lampbanks providing daily biologically effective UV-B doses equivalent to those under ambient mid-March stratospheric ozone levels or 16% (‘low-enhanced UV-B’) or 32% (‘high-enhanced UV-B’) ozone depletion levels for Morgantown, WV, USA. Total and aboveground biomass of plants was less under low-enhanced UV-B, but similar to ambient controls under high-enhanced UV-B. Concentrations of UV-B-absorbing compounds in leaves (area basis) increased under high-enhanced UV-B by about 20%, but were similar to ambient controls under low-enhanced UV-B. More effective protection due to higher screening-compound concentrations in plants under high-enhanced UV-B may explain why biomass production was not reduced. Plants under high-enhanced UV-B also had more reproductive biomass and produced more flowers, and had less root mass, than plants under ambient or low-enhanced UV-B. Concentrations of leaf total chlorophyll were not affected by UV-B treatment. While UV-B treatment had no affect on concentrations of UV-B-absorbing compounds in ovaries, concentrations in pollen from plants under both enhanced-UV-B treatments were >40% greater than ambient controls

  6. Elevated UV-B radiation increased the decomposition of Cinnamomum camphora and Cyclobalanopsis glauca leaf litter in subtropical China

    Energy Technology Data Exchange (ETDEWEB)

    Song, Xinzhang Z.; Zhang, Huiling L.; Jiang, Hong; Yu, Shuquan Q. [Zhejiang Agriculture and Forestry Univ., Lin' an (China). The Nurturing Station for the State Key Lab. of Subtropical Silviculture; Zhejiang Agriculture and Forestry Univ., Lin' an (China). Zhejiang Provincial Key Lab. of Carbon Cycling and Carbon Sequestration in Forest Ecosystems; Chang, Scott X. [Alberta Univ., Edmonton (Canada). Dept. of Renewable Resources; Peng, Changhui H. [Quebec Univ., Montreal (Canada). Inst. of Environment Sciences

    2012-03-15

    Ultraviolet-B (UV-B) radiation reaching the earth's surface has been increasing due to ozone depletion and can profoundly influence litter decomposition and nutrient cycling in terrestrial ecosystems. The role of UV-B radiation in litter decomposition in humid environments is poorly understood; we thus investigated the effect of UV-B radiation on litter decomposition and nitrogen (N) release in a humid subtropical ecosystem in China. We conducted a field-based experiment using the litterbag method to study litter decomposition and N release under ambient and elevated (31% above ambient) UV-B radiation, using the leaf litter of two common tree species, Cinnamomum camphora and Cyclobalanopsis glauca, native to subtropical China. Elevated UV-B radiation significantly increased the decomposition rate of C. camphora and C. glauca leaf litter by 16.7% and 27.8%, respectively, and increased the N release from the decomposing litter of C. glauca but not C. camphora. Elevated UV-B radiation significantly accelerated the decomposition of litter of two native tree species and the N release from the decomposition litter of C. glauca in humid subtropical China, which has implications for soil carbon flux and forest productivity. (orig.)

  7. Effects of ambient versus reduced UV-B radiation on high arctic ¤Salix arctica¤ assessed by measurements and calculations of chlorophyll a fluorescence parameters from fluorescence transients

    DEFF Research Database (Denmark)

    Albert, K.R.; Mikkelsen, Teis Nørgaard; Ro-Poulsen, H.

    2005-01-01

    received approximately 90 and 40% of the ambient UV-B irradiance, respectively. The effects were examined through recordings of chlorophyll a fluorescence transients, determination of biomass and analysis of total carbon and nitrogen content and amount of soluble flavonoids in the leaves. The processing...... of light was analysed by means of the chlorophyll a fluorescence transient, using the so-called JIP test, as evolved by Reto J. Strasser and his coworkers. Reduction of the UV-B irradiance caused a rise in many of the fluorescence parameters during July, but not in August (late season). Thus increases...... on fluorescence parameters that were directly measured (e.g. F0 and FM) and those that were derived (e.g. quantum efficiencies, parameters per PSII reaction centres and per cross-section of leaf sample) are discussed in relation to one another, in relation to daily and seasonal variation, and from the perspective...

  8. Is UV-B radiation affecting charophycean algae in shallow freshwater systems?

    NARCIS (Netherlands)

    de Bakker, NVJ; van Bodegom, PM; van de Poll, WH; Boelen, P; Nat, E; Rozema, J; Aerts, R

    2005-01-01

    The objective of this study was to determine the effects of UV-B radiation on charophycean algae under natural conditions, since charophytes enhance water transparency in freshwater systems and levels of UV-B radiation have increased by ozone depletion. Potential and actual UV-B effects were studied

  9. Response of cotton and sorghum to several levels of subambient solar UV-B radiation: a test of the saturation hypothesis

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, R.S.; Day, T.A. [Arizona Stat. Univ., School of Life Sciences, Tempe AZ (United States)

    2004-11-01

    Some have proposed that plant responses to above-ambient or supplemented levels of solar ultraviolet-B radiation (UV-B; 280315 nm) are typically subtle because targets or receptors in plants become saturated. If true, in solar UV-B filter exclusion experiments we would expect that plant responses would level off or'saturate' as doses approached ambient levels. To test this so-called 'saturation hypothesis' we examined the response of Gossypium hirsutum (cotton) and Sorghum bicolor (sorghum) to filter exclusions that provided five levels of biologically effective UV-B, ranging from 36 to 91% of ambient solar levels in Arizona, USA. UVB dose had no effect on biomass production of either species. As UV-B dose increased or approached ambient, individual leaves of S. bicolorwere smaller, but plants produced more tillers and leaves. In G. hirsutum, individual leaves as well as total plant leaf area were smaller, but plants produced more branches. Bulk concentrations of soluble UV-B absorbing compounds increased with UV-B dose in both species. Leaf epidermal UV-B transmittance, assessed with the chlorophyll fluorescence technique, declined with increasing UV-B dose, and was well correlated with bulk concentrations of soluble UV-B screening compounds. Bulk concentrations of insoluble or wall-bound UV-B absorbing compounds were not affected by UV-B dose. The intensity of UV-induced blue fluorescence from leaf surfaces was strongly correlated with bulk concentrations of wall-bound UV-B absorbing compounds, and this signal has the potential to provide a rapid, non-invasive method to estimate concentrations of these compounds, which are time-consuming to extract. While both species were responsive to solar UV-B, responses did not appear to become saturated as doses approached ambient levels. Rather, responses required a threshold dose of >70% of solar ambient UVB leveis before they became apparent. (au)

  10. Effects of enhanced UV-B radiation on plant chemistry: nutritional consequences for a specialist and generalist lagomorph.

    Science.gov (United States)

    Thines, Nicole J; Shipley, Lisa A; Bassman, John H; Fellman, John K; Mattison, D Scott; Slusser, James R; Gao, Wei

    2007-05-01

    Ultraviolet-B (UV-B) radiation has been increasing in temperate latitudes in recent decades and is expected to continue rising for some time. Enhanced UV-B radiation can change plant chemistry, yet the effects of these changes on mammalian herbivores are unknown. To examine the influence of enhanced UV-B radiation on nutrition of a specialist and generalist hindgut fermenter, we measured nutritional and chemical constituents of three common North American range plants, big sagebrush (Artemisia tridentata), yarrow (Achillea millefolium), and bluebunch wheatgrass (Pseudoregneria spicata), and how these changes influenced in vitro dry matter digestibility and in vivo digestibility by pygmy rabbits (Brachylagus idahoensis) and eastern cottontails (Sylvilagus floridanus). Forages were irradiated for 3 mo with ambient (1x) or supplemental (1.6x) UV-B radiation representing a 15% ozone depletion for Pullman, WA, USA. Enhanced UV-B radiation had minimal effects on the nutritional content and the tannin-binding capacity of forages. Similarly, the terpene concentration in sagebrush and yarrow was not affected by higher UV-B irradiances. Flavonoid compounds increased in sagebrush but decreased in yarrow. Rabbit preference and intake was not affected by treatment levels for any forage species and no differences were found between treatments for dry matter, fiber, protein digestibility, and apparent digestible energy. PMID:17406969

  11. Responses of antioxidant defense system of Lespedeza davurica to enhanced UV-B radiation

    International Nuclear Information System (INIS)

    The objective of this study was to investigate the effects of different UV-B radiation intensity (CK, T1, T2) on antioxidant defense system and other related indicators of Lespedeza davurica (Laxm.) Schindl. Malonaldehyde (MDA), ascorbic acid (AsA) and carotenoid (Car) contents, as well as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) activities of leaves from Lespedeza davurica under different UV-B radiation intensity were investigated. Samples were collected once every three days. The UV-B treatment was continued 15 days. Result indicated that SOD and POD activities decreased, APX and POD activities increased with UV-B radiation enhanced during the whole treatment time. SOD, POD and CAT activities decreased with UV-B radiation intensity increasing. APX activity increased during the first 9-day treatment with radiation intensity increasing then decreased with radiation intensity increasing. UV-B radiation increased AsA content, decreased Car content. Both AsA and Car contents decreased with radiation intensity increasing when compared with control. O2- and MDA increased with radiation intensity increasing. All other tested indicators increased except SOD and POD activity as well as AsA content decreased after UV-B radiation treatment. Comprehensive evaluation of subordinate function showed that UV-B radiation reduced the antioxidant capacity of Lespedeza davurica, and the antioxidant capacity decreased with UV-B radiation intensity increasing. (author)

  12. Enhanced UV-B radiation increases glyphosate resistance in velvetleaf (Abutilon theophrasti).

    Science.gov (United States)

    Yin, Lina; Zhang, Mingcai; Li, Zhaohu; Duan, Liusheng; Wang, Shiwen

    2012-01-01

    Depletion of the ozone layer leads to increasing UV-B radiation on the earth's surface, which may affect weeds and their responses to herbicides. However, the effect of increased UV-B radiation on weeds and the interaction of weeds and herbicides are still obscure. The objective of this study was to compare glyphosate efficacy on velvetleaf that was grown under with and without increased UV-B radiation. Leaf area, dry weight and net photosynthesis of velvetleaf seedlings were adversely affected by increased UV-B radiation. Leaf cuticle wax significantly increased by 28% under increased UV-B radiation. Glyphosate efficacy on velvetleaf, evaluated by shoot dry weight, was significantly decreased by increased UV-B radiation. Exposure to increased UV-B radiation significantly decreased (14)C-glyphosate absorption from 49% to 43%, and also resulted in less (14)C-glyphosate translocation out of treated leaves and less glyphosate accumulation in newly expanded leaves. The decrease in glyphosate efficacy was due to changes in absorption and distribution, which were attributed to increased cuticle wax and decreased photosynthesis caused by increased UV-B radiation. These results suggest that the responses of weeds to herbicides may be affected by increased UV-B radiation, to the extent that higher rates may be required to achieve the desired effects.

  13. Effects of UV-B radiation on the growth interaction of Ulva pertusa and Alexandrium tamarense

    Institute of Scientific and Technical Information of China (English)

    CAI Heng-jiang; TANG Xue-xi; ZHANG Pei-yu; DONG Dong; QU Liang

    2005-01-01

    Enhanced UV-B(280- 320 nm) radiation resulting from ozone depletion is one of global environmental problems. Not only marine organisms but also marine ecosystems can be affected by enhanced UV-B radiation. The effects of UV-B radiation on interaction of macro-algae and micro-algae were investigated using Ulva pertusa Kjellman and Alexandrium tamarense as the materials in this study.The results demonstrated that UV-B radiation could inhibit the growth of Ulva pertusa and Alexandrium tamarense when they were both mono-cultured, and the growth inhibition of algae was more significant with increasing doses of UV-B radiation. Alexandrium tamarense could inhibit the growth of Ulva pertusa in mixed culture, and the growth inhibition was more significant when increasing the initial cell density. However, Ulva pertusa could inhibit the growth of Alexandriurm tamarense in early phase and stimulate the growth in latter phase when they were grown in mixed culture. Lower initial cell density(102 cell/mi) of Alexandriurm tamarense could inhibit the growth of Ulva pertusa under UV-B radiation treatment,however, with the initial cell density increasing(103 and 104 cell/ml), the growth of Ulva pertusa was stimulated under lower dose of UV-B radiation and inhibited under higher dose of UV-B radiation by Alexandrium tamarense.Compared with that in mixed culture, Ulva pertusa showed more positive inhibition to the growth of Alexandrium tamarense under UV-B radiation treatment.

  14. Different responses to UV-B enhanced solar radiation in radish and carrot

    International Nuclear Information System (INIS)

    Radish (Raphanus sativus L.) and carrot (Daucus carota L.), plants with underground storage organs grown in the field, were exposed to either ambient (UVA) or 20 % UV-B (UVE) enhanced solar radiation till their root yield stage. In radish, UVE produced a significant increase in shoot and root fresh mass (FM), increase in the contents of chlorophyll, carotenoids, flavonoids, and total proteins per unit FM, Hill reaction rate, and root yield. In contrast, carrot responded negatively to UVE showing a loss in the above parameters. (author)

  15. The effect of exposure to enhanced UV-B radiation on the penetration of monochromatic and polychromatic UV-B radiation in leaves of Brassica napus

    International Nuclear Information System (INIS)

    Using quartz optical fibres, penetration of both monochromatic (310 nm) and polychromatic UV-B (280–320 nm) radiation in leaves of Brassica napus L. (cv. Ceres) was measured. Plants were grown under either visible light (750 μmol m−2 s−1 photosynthetically active radiation) or with the addition of 8. 9 KJ m−2 day−1 biologically effective UV-B (UV-BBE) radiation. Results showed that of the 310 nm radiation that penetreated the leaf, 90% was within the intial one third of the leaf with high attenuation in the leaf epidermis, especially in UV-treated plants. Polychromatic UV-B radiation, relative to incident radiation, showed a relatively uniform spectral distribution within the leaf, except for collimated radiation. Over 30% of the UV-screening pigments in the leaf, including flavonoids, were found in the adaxial epidermal layer, making this layer less transparent to UV-B radiation than the abaxial epidermis, which contained less than 12% of the UV-screening pigments. UV-screening pigments increased by 20% in UV-treated leaves relative to control leaves. Densely arranged epicuticular wax on the adaxial leaf surface of UV-treated plants may have further decreased penetration of UV-B radiation by reflectance. An increased leaf thickness, and decreases in leaf area and leaf dry weight were also found for UV-treated plants. (author)

  16. Effect of UV- B radiation on the feeding behavior of the rotifer Brachionus plicatilis

    Institute of Scientific and Technical Information of China (English)

    FENG Lei; LI Xin; WANG Jinhe; HAN Honglei; TANG Xuexi; CHEN Xiguang

    2007-01-01

    Effect of UV - B radiation on the feeding behaviour of marine zooplankton is important to assessing the health harm of marine ecosystem due to the gradually enhanced UV - B radiation in air. However, there are a few studies on this topic. The feeding behavior of the rotifer, Brachionus plicatilis, under the treatment of UV - B radiation on five species of microalgae, i. e. , Chlorella sp. ,Tetraselmis chuii, Isochrysis galbana Park 8701, Chaetoceros muelleri Lermumerman, and Nitzschia clostertum, was studied. The results showed that the filtering and feeding rates of the rotifer decreased significantly with the dose increase of UV - B radiation when fed with five species of microalgae respectively (P < 0.05 ) which indicates UV - B radiation inhibits the feeding activities of the rotifer on microalage. The mixed culture experiments shows the rotifer preferred to feed Chlorella sp. , then C. muelleri, I.galbana, N. clostertum and T. chuii in turn if without UV - B radiation. Under the highest dose of UV - B radiation treatment (2.70 kJ/m2) , the rotifer preferred to feed C. muelleri, then Chlorella sp. , N. clostertum, I. galbana and T. chuii in turn.Chlorella sp. , I. galbana and C. muelleri became the more favorite foods of the rotifer while T. chuii and N. clostertum became less favorite foods. The change of feeding rate and feeding selectivity of zooplankton driven by the enhanced UV - B radiation will lead to the change in the structure of phytoplankton community.

  17. The effects of UV-B radiation on European heathland species

    DEFF Research Database (Denmark)

    Björn, Lars O.; Callaghan, T. V.; Johnsen, Ib;

    1997-01-01

    The effects of enhanced UV-B radiation on three examples of European shrub-dominated vegetation were studied in situ. The experiments were in High Arctic Greenland, northern Sweden and Greece, and at all sites investigated the interaction of enhanced UV-B radiation (simulating a 15% reduction in ...

  18. Effects of UV-B Radiation and Water Stress on Soybean Yield

    Institute of Scientific and Technical Information of China (English)

    REN Hongyu; XU Haiming; LI Dongming; HUANG Rui; WANG Licheng

    2009-01-01

    Soybean Dongnong 47 was subjected to the experiments of increasing UV-B radiation and water stress on soybean yield components in different growth periods. The results showed that 100-seed weight greatly increased during the early stage of pod filling in the treatment of weak UV-B radiation, seed number per plant as well as seed weight per plant and Dongnong47 yield also increased, while the yield and yield components of Dongnong47 during the blossom to mature period were negatively affected in the treatment of intensive UV-B radiation. 100-seed weight of Dongnong47 all increased in the double factor treatments of UV-B radiation and water stress, with the drought intensified, seed number per plant, seed weight per plant and yield of Dongnong47 decreased, the change of 100-seed weight were various and the antagonistic action of UV-B radiation and water stress were related with their intensity.

  19. Physiological and ultralstructural changes of Chlorella sp. induced by UV-B radiation

    Institute of Scientific and Technical Information of China (English)

    YU Juan; TANG Xuexi; ZHANG Peiyu; TIAN Jiyuan; DONG Shuanglin

    2005-01-01

    In order to investigate the mechanisms of enhanced UV-B radiation on algae, the effects of UV-B radiation on the physiological and ultrastructural changes of Chlorella sp. were examined. The results showed that UV-B radiation could inhibit the growth and photosynthesis of microalgae. UV-B radiation at lower doses increased the photosynthetic pigment (chlorophyll a (Chla) and carotenoid (Car)) contents, while at higher doses of UV-B radiation Chla and Car contents were decreased. The ultrastructure of Chlorella sp.without exposure to UV-B showed that the thylakoidlamellae were clear and regular, the stroma of its chloroplast was apparent and clear.The globules with photosynthetic pigments and the cristae of mitochondria were clearly seen. After exposure to UV-B radiation at dose of 2.88 kJ/m2, the thylakoid lamellae of Chlorella sp. were lost and dissolved, the globules which contained photosynthetic pigments in chloroplast were bleached; some mitochondria cristae were dissolved; slight plasmolysis was found in some Chlorella sp. cells. After exposure to 5.76 kJ/m2 UV-B radiation, the thylakoid was in disarray and disintegration, plasmolysis was found in most cells, and the cell wall was broken and began to fall out. Many blank areas were observed in cells, mitochondria were seriously deformed and most of the mitochondria cristae were dissolved. Also, globules containing photosynthetic pigments in chloroplast were bleached and some empty globules were found in chloroplast. Therefore, UV-B radiation could damage cell structure of Chlorella sp., and this damage increased with the dose of UV-B radiation they exposed to.

  20. Effects of Elevated Solar UV-B Radiation from Ozone Depletion on Terrestrial Ecosystems

    Institute of Scientific and Technical Information of China (English)

    LIU Qing; Terry V. Callaghan; ZUO Yuanyuan

    2004-01-01

    In the last three decades much research has been carried out to investigate the biological effects of a thinning stratospheric ozone layer accompanied by an enhanced level of solar ultraviolet-B radiation at the Earth's surface. Enhanced UV-B radiation affects ecosystems in many ways directly and indirectly. The responses can be biochemical, physiological, morphological or anatomical, and the direction of the response can vary between different species, communities and ecosystems. In this paper we firstly introduce general concepts, and methods for measuring the ecological effects of UV-B radiation. Secondly, we provide an overview interpretation of the effects of enhanced UV-B on terrestrial ecosystems from recent studies. These studies include effects of UV-B on growth and reproduction, composition of communities, competitive balance, decomposition of litter, and interactions with other factors etc. Finally, we recommend future research directions to identify the effects of elevated UV-B radiation on ecosystems in China.

  1. Biological responses to current UV-B radiation in Arctic regions

    DEFF Research Database (Denmark)

    Albert, Kristian; N. Mikkelsen, Teis; Ro-Poulsen, Helge

    Depletion of the ozone layer and the consequent increase in solar ultraviolet-B radiation (UV-B) may impact living conditions for arctic plants significantly. In order to evaluate how the prevailing UV-B fluxes affect the heath ecosystem at Zackenberg (74°30'N, 20°30'W) and other high...

  2. Response of Marine Microalgae, Heterotrophic Bacteria and Their Relationship to Enhanced UV-B Radiation

    Institute of Scientific and Technical Information of China (English)

    ZHOU Wenli; TANG Xuexi; XIAO Hui; WANG You; WANG Renjun

    2009-01-01

    Ozone depletion in the stratosphere has enhanced solar UV-B radiation reaching the Earth surface and has brought about significant effects to marine ecosystems. The effects of enhanced UV-B radiation on marine microalgae, heterotrophic bacteria and the interaction between them are discussed. The effects on marine microalgae have been proved to occur at molecular, cellular and population levels. Enhanced UV-B radiation increases microalgal flavonoid content but decreases their chlorophyll content and pho-tosynthesis rate; this rachation induces genetic change and results in DNA damage and change of protein content. There have been fewer studies on the effects of UV-B radiation on marine heterotrophic bacteria. Establishment of a nucroalgal ecological dynamic model at population and community levels under UV-B radiation has gradually become a hotspot. The effects of enhanced UV-B radiation on microalgae communities, heterotrophic bacterial populations and interaction between them will become a focus in the near future. This paper will make an overview on the studies concerning the effects of enhanced UV-B radiation on marine microal-gae and heterotrophic bacteria and the interaction between them.

  3. The lichens Xanthoria elegans and Cetraria islandica maintain a high protection against UV-B radiation in Arctic habitats.

    Science.gov (United States)

    Nybakken, Line; Solhaug, Knut Asbjørn; Bilger, Wolfgang; Gauslaa, Yngvar

    2004-07-01

    This study reports UV screening pigments in the upper cortices of two widespread lichens collected in three sun-exposed locations along a latitudinal gradient from the Arctic lowland to alpine sites of the Central European Alps. Populations from the Alps receive 3-5 times higher UV-B irradiance than their Arctic counterparts from Svalbard because of latitudinal and altitudinal gradients in UV-B irradiance. In Cetraria islandica, the screening capacity of melanin in the upper cortices was assessed by direct measurements of cortical transmittance (250-1,000 nm). A comparison of cortical transmittances in brown sun-exposed and pale shade-adapted forest C. islandica thalli showed that fungal melanins strongly absorb both UV-B and photosynthetically active radiation (PAR). For Xanthoria elegans cortical UV-B absorbing pigments, mainly the orange parietin, were extracted and quantified. Field experiments with extracted, parietin-deficient X. elegans thalli cultivated under various filters showed that UV-B was essential for the induction of parietin synthesis. The parietin resynthesis in these parietin-deficient samples increased with decreasing latitude of their location in which they had been sampled, which may imply that the synthesis of pigments is habitat specific. However, no latitudinal gradient in cortical screening capacity was detected for any of the two species investigated in the field. This implies that Arctic populations maintain a high level of screening pigments in spite of low ambient UV-B, and that the studied lichen species presumably may tolerate an increase in UV-B radiation due to the predicted thinning of the ozone layer over polar areas.

  4. Effect of UV-B radiation on leaf optical properties measured with fibre optics

    International Nuclear Information System (INIS)

    Changes in the internal light microenvironment in leaves of plants of Brassica campestris L. cv. Emma, B. carinata L., and Medicago saliva L. cv. Armour in response to exposure to UV-B (UV-B, 280–320 nm) radiation were measured using a fibreoptic microprobe. Plants were exposed for 2 weeks either to high visible light or to supplemental ultraviolet-B radiation. The spectral regime (400–700 nm; PAR ) was measured either midway through the leaf palisade or the spongy mesophyll. After exposure to UV-B radiation leaves of Brassica campesiris attenuated transmitted light more than the controls. At the same time both forward and back scattered light increased in the palisade and spongy mesophylls. In contrast, UV-treatment of Medicago saliva leaves increased light transmission into the palisade, while the back scattered component showed little change. Leaves of cariiwla showed little change in response to UV. Other responses to UV-B radiation included increases in leaf thickness, decreased total chlorophyll content, and changes in UV-B screening pigments and chlorophyll fluorescence induction kinetics. Brassica campestris was most sensitive to exposure to enhanced levels of UV-B radiation, whereas leaves of B. carinata were the least sensitive. Our data indicate that exposure to UV-B radiation altered the light microenvironment within leaves of the species different ways. These changes appeared to be caused by alterations in pigment content and leaf anatomy. In turn, the altered distribution of PAR within the leaf could influence photosynthesis

  5. The effects of UV-B radiation on European heathland species

    International Nuclear Information System (INIS)

    The effects of enhanced UV-B radiation on three examples of European shrub-dominated vegetation were studied in situ. The experiments were in High Arctic Greenland, northern Sweden and Greece, and at all sites investigated the interaction of enhanced UV-B radiation (simulating a 15% reduction in the ozone layer) with artificially increased precipitation. The Swedish experiment also involved a study of the interaction between enhanced UV-B radiation and elevated CO2 (600 ppm). These field studies were supported by an outdoor controlled environment study in the United Kingdom involving modulated enhancement of UV-B radiation in combination with elevated CO2 (700 ppm). Effects of the treatments on plant growth, morphology, phenology and physiology were measured. The effects observed were species specific, and included both positive and negative responses to the treatments. In general the negative responses to UV-B treatments of up to three growing seasons were small, but included reductions in shoot growth and premature leaf senescence. Positive responses included a marked increase in flowering in some species and a stimulation of some photosynthetic processes. UV-B treatment enhanced the drought tolerance of Pinus pinea and Pinus halepensis by increasing leaf cuticle thickness. In general, there were few interactions between the elevated CO2 and enhanced UV-B treatments. There was evidence to suggest that although the negative responses to the treatments were small, damage may be increasing with time in some long-lived woody perennials. There was also evidence in the third year of treatments for effects of UV-B on insect herbivory in Vaccinium species. The experiments point to the necessity for long-term field investigations to predict the likely ecological consequences of increasing UV-B radiation. (author)

  6. Crosstalk between MAV and MEP pathways in vitro grape plants exposed to UV-B radiation

    International Nuclear Information System (INIS)

    The synthesis of terpenoids from IPP (isopentenyl diphosphate) proceeds in plants throughout two pathways, the MVA (mevalonic acid) in cytosol and the MEP (2-C-methyl-D-erythritol 4-phosphate) in plastids. Ultraviolet-B (UV-B) radiation induced the synthesis of terpenes in in vitro grape plants according to the fluence rate. Low intensity UV-B promoted the MVA pathway while high intensity UV-B stimulated the MEP pathway. Mevastatin is known to inhibit the enzyme HMG-CoA reductase blocking terpene synthesis in cytosol. In vitro plants growing 45 days under 16 h-photoperiod (100 μmol m-2 s-1) were fed at the apex with mevastatin and then exposed to an UV-B dose administrated at two intensities: low UV-B (8.25 μW cm-2,16 h) or high UV-B (33 μW cm-2,4 h). Methanol: chloroform extracts were analyzed by GC-EIMS and compared with controls without mevastatin. Levels of γ-Sitosterol and Stigmasterol were significantly increased under low intensity UV-B in the controls. The plants treated with the inhibitor showed a significant decrease of both sterols and a decrease in the plastidial terpenes but sterols were higher under UV-B. These results suggest an IPP crosstalk between the MAV and MEP pathways under restrictive conditions. (authors)

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

    Science.gov (United States)

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

    2015-05-01

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

  8. Long-term structural canopy changes sustain net photosynthesis per ground area in high arctic Vaccinium uliginosum exposed to changes in near-ambient UV-B levels.

    Science.gov (United States)

    Boesgaard, Kristine S; Albert, Kristian R; Ro-Poulsen, Helge; Michelsen, Anders; Mikkelsen, Teis N; Schmidt, Niels M

    2012-08-01

    Full recovery of the ozone layer is not expected for several decades and consequently, the incoming level of solar ultraviolet-B (UV-B) will only slowly be reduced. Therefore to investigate the structural and photosynthetic responses to changes in solar UV-B we conducted a 5-year UV-B exclusion study in high arctic Greenland. During the growing season, the gas exchange (H₂O and CO₂) and chlorophyll-a fluorescence were measured in Vaccinium uliginosum. The leaf dry weight, carbon, nitrogen, stable carbon isotope ratio, chlorophyll and carotenoid content were determined from a late season harvest. The net photosynthesis per leaf area was on average 22% higher in 61% reduced UV-B treatment across the season, but per ground area photosynthesis was unchanged. The leaf level increase in photosynthesis was accompanied by increased leaf nitrogen, higher stomatal conductance and F(v)/F(m). There was no change in total leaf biomass, but reduction in total leaf area caused a pronounced reduction of specific leaf area and leaf area index in reduced UV-B. This demonstrates the structural changes to counterbalance the reduced plant carbon uptake seen per leaf area in ambient UV-B as the resulting plant carbon uptake per ground area was not affected. Thus, our understanding of long-term responses to UV-B reduction must take into account both leaf level processes as well as structural changes to understand the apparent robustness of plant carbon uptake per ground area. In this perspective, V. uliginosum seems able to adjust plant carbon uptake to the present amount of solar UV-B radiation in the High Arctic. PMID:22211955

  9. Enhanced UV-B radiation alleviates the adverse effects of summer drought in two Mediterranean pines under field conditions [ozone depletion

    International Nuclear Information System (INIS)

    The effects of enhanced UV-B (290-320 nm) radiation on two native Mediterranean pines (Pinus pinea L., Pinus halepensis Mill.) were recorded during a one-year field study. Plants received ambient or ambient plus supplemental UV-B radiation (simulating a 15% stratospheric ozone depletion over Patras. Greece, 38.3°N. 29.1°E) and only natural precipitation, i.e. they were simultaneously exposed to other natural stresses. particularly water stress during summer. Supplemental UV-B irradiation started in early February, 1993 and up to late June, no effects were observed on growth and photochemical efficiency of photosystem II, as measured by chlorophy II fluorescence induction. Water stress during the summer was manifested in the control plants as a decline in the ratio of variable to maximum fluorescence (Fv/Fm), the apparent photon yield for oxygen evolution (φI) and the photosynthetic capacity at 5% CO2 (Pm). In addition, a partial needle loss was evident. Under supplemental UV-B radiation, however, the decreases in Fv/Fm, φi, and Pm. as well as needle losses were significantly less. Soon after the first heavy autumn rains. photosynthetic parameters in both control and UV-B treated plants recovered to similar values. but the transient summer superiority of UV-B irradiated plants resulted in a significant increase in their dry weight measured at plant harvest. during late January. 1994. Plant height. UV-B absorbing compounds, photosynthetic pigments and relative water content measured at late spring. late summer and at plant harvest, were not significantly affected by supplemental UV-B radiation. The results indicate that enhanced UV-B radiation may be beneficial for Mediterranean pines through a partial alleviation of the adverse effects of summer drought. (author)

  10. Susceptibility of pollen to UV-B radiation: an assay of 34 taxa

    International Nuclear Information System (INIS)

    Much of the ultraviolet-B radiation (UV-B) research on plants has concentrated on vegetative plant parts, and only a small fraction has dealt with the reproductive system. The present study analyzed pollen grains of 34 taxa germinated and grown under two levels of UV-B radiation (187 and 460 mW/m2) or no UV-B (control group). Visible radiation at 260 micromoles m-2s-1 was present in all treatments. Taxa included those with binucleate and trinucleate pollen types. We detected differences among species. A significant reduction in pollen germination occurred in only five species. Pollen tubes of 50% of the species showed significant reduction in length. Trinucleate pollen types were more likely to exhibit tube length reduction than the binucleate types. Proportionately more monocotyledonous species were sensitive to UV-B treatment than dicotyledonous species, and proportionately more wild species were sensitive than cultivated species and pollen collected from plants growing in the field were somewhat more sensitive than pollen collected from plants grown in the greenhouse. Species in which pollination occurred earlier in the season were more likely to be susceptible to UV-B radiation than those for which anthesis took place later in the season, suggesting a possible adaptation to UV-B radiation. (author)

  11. Response of hoary alyssum (Berteroa incana L. to UV-B radiation

    Directory of Open Access Journals (Sweden)

    Agnieszka Stokłosa

    2012-12-01

    Full Text Available This greenhouse experiment evaluated the response of hoary alyssum plants, up to the rosette phase, to different levels of UV-B radiation. The experiment was carried out in the chambers, equipped with UV-B lamps, emitting biologically effective UV-B radiation of 0 (control, 4, 6 or 8 kJ. As a result, specific traits of the plants such as: leaf number, lamina length, leaf area, specific leaf weight, relative chlorophyll content and shoot biomass were unaffected by any of the UV-B treatments. Significant reductions in the share of large leaves, leaf stalk length and root biomass were noted for plants growing under 8 kJ UV-BBE.

  12. Effects of increased UV-B radiation and elevated levels of tropospheric ozone on physiological processes in European beech (Fagus sylvatica)

    International Nuclear Information System (INIS)

    As a consequence of the ongoing reduction of the stratospheric ozone layer, the vegetation is exposed to increasing levels of UV-B radiation (280–320 nm). In addition ozone in the troposphere is a pollutant and also capable of affecting the photosynthetic machinery. In this study, 5-year-old European beech trees were exposed from 1 July to October 1993 to two levels of UV-B radiation and two levels of ozone, alone and in combination, in open-top chambers equipped with lamps. The simulated UV-B levels corresponded to either clear sky ambient level or a 14% decrease in the stratospheric ozone column over eastern Denmark, resulting in a 23% difference in biologically effective UV-B (UV-BBE) irradiance. The maximum UV-BBE given was 8.61 kJ m−2 day−1. The ozone levels were either the ambient (average 32 nl l−1) or ambient with ozone addition (average resulting concentration 71 nl l−1). Compared to the control treatment (ambient UV-B, ambient O3) the elevated levels of UV-B and O3 affected the trees negatively, expressed as declines in net photosynthesis (Pn), stomatal conductance (gs), chlorophyll fluorescence (Fv/Fm) and acceleration of senescence, measured as yellowing of the leaves. The UV-B treatment induced stomatal closure before the other treatments did. The magnitude of the decreases in Pn and Fv/Fm occurred in the order: control <UV-B UV-B and O3. Compared to the control, the combination treatment with high levels accelerated the visual senescence processes by ca 27 days, while for high UV-B and O3 alone, there was an acceleration by 14 and 21 days, respectively. UV-B and O3 in combination enhanced the negative effects compared with UV-B and O3 alone. The Pn and Fv/Fm results could be related to this acceleration process. The chamber effect was investigated by comparing the control plots with a plot without open-top chamber. The trees in the chambers showed a higher Pn and Fv/Fm and a 14-day delayed senescence compared to the trees outside

  13. The effects of enriched CO2 and enhanced UV-B radiation on ultra structure of Dunaliella salina, singly and in combination

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The effects of ambient CO2/ambient UV-B, enriched CO2/ambient UV-B, ambient CO2/enhanced UV-B, and enriched CO2/enhanced UV-B on the ultrastructure of Dunaliella salina were investigated. (1) The ultrastructure of D.salina cell in the control experiment showed that the arrangement of thylakoid lamellae was regular, and there were many large starch grains among the thylakoid lamellae.A prominent well-developed pyrenoid was found in the middle of the chloroplast. Nucleus envelope and nucleolus were clearly observed. The Golgi apparatus accompanied by numerous vesicles with a compact arrangement of cisternae and the peripheral tips of the cisternae were swollen to a size comparable to that of some of the associated vesicles. (2) The ultrastructure of D. salina cell in enriched CO2 showed that the arrangement ofthylakoid was regular and the lamellae were vivid. Developed pyrenoids were found in the low-CO2-grown cells, but not in the high-CO2-grown cells. The mitochondria cristae were vivid. The arrangement of Golgi apparatus was compact. (3) The ultrastructure of D. salina cell in enhanced UV-B showed that the thylakoid was dissolved and the cells had a less developed pyrenoid or no detectable pyrenoid. Part of the nucleus envelope was dissolved. The number ofmitochondria was increased and some mitochondria cristae were disintegrated. The starch grains were broken apart into many small starch grains. The Golgi apparatus with a loose arrangement of cisternae and the peripheral tips of the Golgi cisternae were not especially swollen, with several large associated vesicles. (4) The ultrastructure of D. salina cell in the enriched CO2/enhanced UV-B showed that part of the thylakoid and nucleus envelopes of some cells were dissolved. The pyrenoid was larger than that of the enhanced UV-B. There were many mitochondria between stroma and chloroplast membrane, but mitochondria cristae were partly dissolved. Many small starch grains were accumulated in cells. The starch sheath

  14. Photomorphogenic effects of UV-B radiation on plants: consequences for light competition

    International Nuclear Information System (INIS)

    A combination of field and labotatory studies were conducted to explore the nature of photomorphogenic effects of ultraviolet-B radiation (UV-B; 280–320 nm) on plant morphology and to evaluate the ecological consequences of these alterations in morphology for interspecific competition. Under laboratory conditions, seedlings of cucumber (Cucumis sativus L.) and tomato (Lycopersicon esculentum Mill.) exhibited appreciable (ca. 50%) and rapid (< 3h) inhibition in hypocotyl elongation in response to UV-B exposure. In cucumber, this inhibition was reversible, occurred without any associated changes in dry matter production and was caused by UV-B incident on the cotyledons and not the stem or growing tip. Inhibition of stem elongation in etiolated tomato seedlings occurred at least 3 h prior to the onset of accumulation of UV-absorbing pigments and monochromatic UV supplied against a background of visible radiation revealed maximum effectiveness in inhibition around 300 nm. Collectively, these findings suggest that a specific, but yet unidentified, UV-B photoreceptor is involved in mediating certain morphological responses to UV-B. For mixtures of wheat (Triticum aestivum L.) and wild oat (Avena fatua L.), a common weedy competitor, supplemental UV-B irradiation in the field differentially altered shoot morphology which resulted in changes in canopy structure, light interception and calculated stand photosynthesis. It is argued that, because of its asymmetrical nature, competition for light can potentially amplify the effects of UV-B on shoot morphology and may, therefore, be an important mechanism by which changes in the solar UV-B spectrum associated with stratospheric ozone reduction could alter the composition and character of terrestrial vegetation

  15. Effects of environmental and artificial UV-B radiation on freshwater prawn Macrobrachium olfersi embryos

    Energy Technology Data Exchange (ETDEWEB)

    Nazari, Evelise Maria [Programa de Pos-Graduacao em Ciencias Morfologicas, Instituto de Ciencias Biomedicas, Universidade Federal do Rio de Janeiro, 21949-902 Rio de Janeiro, RJ (Brazil); Universidade Federal de Santa Catarina, Departamento de Biologia Celular, Embriologia e Genetica, Campus Universitario, 88040-900 Florianopolis, SC (Brazil); Ammar, Dib [Universidade do Oeste de Santa Catarina, Departamento de Biologia, Campus Universitario, 89600-000 Joacaba, SC (Brazil); Bem, Andreza Fabro de; Latini, Alexandra [Universidade Federal de Santa Catarina, Departamento de Bioquimica, Campus Universitario, 88040-900 Florianopolis, SC (Brazil); Mueller, Yara Maria Rauh [Universidade Federal de Santa Catarina, Departamento de Biologia Celular, Embriologia e Genetica, Campus Universitario, 88040-900 Florianopolis, SC (Brazil); Allodi, Silvana, E-mail: sallodi@histo.ufrj.br [Programa de Pos-Graduacao em Ciencias Morfologicas, Instituto de Ciencias Biomedicas, Universidade Federal do Rio de Janeiro, 21949-902 Rio de Janeiro, RJ (Brazil)

    2010-06-01

    The recent decrease of the stratospheric ozone has resulted in an increase of ultraviolet-B (UV-B) radiation reaching the Earth's surface. In freshwater ecosystems with transparent water, UV-B rays easily penetrate and potentially cause harmful effects to organisms. In this study, embryos of the prawn Macrobrachium olfersi were used to evaluate the impact of UV-B rays in freshwater environments. We observed three groups of embryos: the first was to assess whether UV-B radiation produced morphological defects and/or biochemical impairments in the laboratory. The second was to check whether embryos with the same impairments as those observed in the laboratory were found in their environment, under natural solar radiation. The third group was the non-irradiated control. The embryos irradiated with 310 mW cm{sup -2} UV-B for 30 min showed morphological alterations similar to those observed in embryos from the environmental control group. The most important effects of the UV-B radiation observed in M. olfersi embryos were morphological (1.2% of the total number of embryos from the environment and 2.8% of the total number of irradiated embryos), pigmentation changes in the eyes (78.0% of the total number of embryos from the environment and 98.9% of the total number of irradiated embryos), and disruption of the chromatophores (46.9% of the total number of embryos from the environment and 95.5% of the total number of irradiated embryos). We also observed an increase in egg volume, which was accompanied by a significant increase in water content in UV-B irradiated groups when compared with aquaria control embryos. In addition, a significant decrease in the mitotic index in eggs exposed to UV-B radiation was detected (0.17 for the embryos from the aquaria control, 0.10 for the embryos of the environmental control, and 0.04 for the irradiated groups). The low levels of NPSH and high levels of TBARS indicated that UV-B rays directly compromised the antioxidant function of

  16. Influence of light, UV-B radiation, and herbicides on wax biosynthesis of cucumber seedlings

    International Nuclear Information System (INIS)

    The behavior of cuticular alkane-1-ols and alkanes were studied in different developmental stages of cucumber seedlings grown in the dark or under white light, with or without UV-B radiation or in presence of wax biosynthesis inhibitors, trichloroacetic acid and metolachlor. Accumulation of alkane-1-ols increased light independently with seedling age. Synthesis of alkanes was strictly light and dose dependent. Addition of UV-B radiation did not alter the amounts of alkanes or alcohols, however, the distribution of homologues was shifted towards shorter chain homologues. Treatments with Cl3AcOH resulted in strong inhibition of alkane accumulation, whereas the amount of alkane-1-ols was changed neither at low nor at moderate concentrations of Cl3AcOH but their homologue distribution shifted towards longer chain lengths. This shifting was depressed in the presence of UV-B. At high concentrations of Cl3Ac0H similar homologue distributions as produced by UV-B (shift to shorter homologues) were observed. Metolachlor treatment resulted in an inhibition of alkane-1-ol production connected with rising amounts of alkanes, predominantly of short chain species. A simple model of wax biosynthesis is proposed which describes the interactions with white light, UV-B radiation and herbicides. (author)

  17. UV-B radiation does not limit carbohydrate level and carbohydrate metabolism in cucumber leaves

    Directory of Open Access Journals (Sweden)

    Magdalena Rybus-Zając

    2014-08-01

    Full Text Available Cucumber is a vegetable exhibiting relatively high sensitivity to environmental stress factors. When it is grown outdoors, from early stages of development there is a real risk of exposure to elevated UV-B radiation. In order to explain the effects of time-dependent UV-B doses on carbohydrate level and metabolism, the photosynthetic activity, accumulation of carbohydrates and activities of carbohydrate-related enzymes were determined in the cucumber leaves. Elevated UV-B radiation led to an increase in the rate of photosynthesis, which was reflected by an increase in SPAD values. Higher photosynthetic activity resulted in an increase in levels of soluble sugars. In view of the above-mentioned results, radiation stress led to a UV-B time-dependent dose increase in the activity of two enzymes decomposing carbohydrate: invertase and glucosidase. Our results suggest that the exposure of cucumber plants to supplemental UV-B doses does not limit the availability of the photoassimilate. Carbohydrates are required to provide not only respiratory energy for protection, maintenance (and repair of plant activity and structure, but also provide biosynthetic carbon skeletons for secondary metabolite synthesis

  18. Effect of UV-B radiation on free amino acid pools of marine diatoms

    Energy Technology Data Exchange (ETDEWEB)

    Doehler, G. (Frankfurt Univ. (Germany, F.R.). Botanisches Institut)

    1985-01-01

    The marine diatoms Asterionella glacialis, Chaetoceros debilis, Ditylum brightwellii and Thalassiosira punctigera were grown for 2 d under different levels of UV-B radiation (439, 717 and 1230 Jm/sup -2/d/sup -1/) at 18 /sup 0/C bubbling with normal air (0.035 vol.% CO/sub 2/). Enhanced levels of UV-B radiation reduced biomass production (dry weight), protein and pigment contents of all tested diatoms. UV-B influence on amides and free amino acid pools - using reversed-phase high-performance liquid chromatography - was found to be species dependent. Thalassiosira cells exposed to UV-B radiation are characterized by an increase of glutamic acid and a reduction of glutamine. The effect of UV-B irradiance on the other diatoms resulted in a marked enhancement of glutamine and a diminution of the glutamic acid concentration. Aspartic acid pool was reduced in nearly all marine diatoms. Results are discussed with reference to the inhibition of the enzymes for the carbon and nitrogen pathway.

  19. Plant Responses to Increased UV-B Radiation: A Research Project

    Science.gov (United States)

    DAntoni, H. L.; Skiles, J. W.; Armstrong, R.; Coughlan, J.; Daleo, G.; Mayoral, A.; Lawless, James G. (Technical Monitor)

    1994-01-01

    Ozone decrease implies more ultraviolet-B (UV-B) radiation reaching the surface of the Earth. Increased UV-B radiation triggers responses by living organisms. Despite the large potential impacts on vegetation, little is known about UV-B effects on terrestrial ecosystems. Long-term ecological studies are needed to quantify the effects of increased UV radiation on terrestrial ecosystems, asses the risks, and produce reliable data for prediction. Screening pigments are part of one of the protective mechanism in plants. Higher concentrations of screening pigments in leaves may be interpreted as a response to increased UV radiation. If the screening effect is not sufficient, important molecules will be disturbed by incoming radiation. Thus, genetics, photosynthesis, growth, plant and leaf shape and size, and pollen grains may be affected. This will have an impact on ecosystem dynamics, structure and productivity. It is necessary to monitor selected terrestrial ecosystems to permit detection and interpretation of changes attributable to global climate change and depleted ozone shield. The objectives of this project are: (1) To identify and measure indicators of the effects of increased solar UV-B radiation on terrestrial plants; (2) to select indicators with the greatest responses to UV-B exposure; (3) to test, adapt or create ecosystem models that use the information gathered by this project for prediction and to enhance our understanding of the effects of increased UV-B radiation on terrestrial ecosystems. As a first step to achieve these objectives we propose a three-year study of forest and steppe vegetation on the North slope of the Brooks Range (within the Arctic circle, in Alaska), in the Saguaro National Monument (near Tucson, Arizona) and in the forests and steppes of Patagonia (Argentina). We selected (1) vegetation north of the Polar Circle because at 70N there is 8% risk of plant damage due to increased UV-B radiation; (2) the foothills of Catalina Mountains

  20. Effects of solar UV-B radiation on canopy structure of Ulva communities from southern Spain.

    Science.gov (United States)

    Bischof, Kai; Peralta, Gloria; Kräbs, Gudrun; Van De Poll, Willem H; Pérez-Lloréns, José Lucas; Breeman, Anneke M

    2002-12-01

    Within the sheltered creeks of Cádiz bay, Ulva thalli form extended mat-like canopies. The effect of solar ultraviolet radiation on photosynthetic activity, the composition of photosynthetic and xanthophyll cycle pigments, and the amount of RubisCO, chaperonin 60 (CPN 60), and the induction of DNA damage in Ulva aff. rotundata Bliding from southern Spain was assessed in the field. Samples collected from the natural community were covered by screening filters, generating different radiation conditions. During daily cycles, individual thalli showed photoinhibitory effects of the natural solar radiation. This inhibition was even more pronounced in samples only exposed to photosynthetically active radiation (PAR). Strongly increased heat dissipation in these samples indicated the activity of regulatory mechanisms involved in dynamic photoinhibition. Adverse effects of UV-B radiation on photosynthesis were only observed in combination with high levels of PAR, indicating the synergistic effects of the two wavelength ranges. In samples exposed either to PAR+UV-A or to UV-B+UV-A without PAR, no inhibition of photosynthetic quantum yield was found in the course of the day. At the natural site, the top layer of the mat-like canopies is generally completely bleached. Artificially designed Ulva canopies exhibited fast bleaching of the top layer under the natural solar radiation conditions, while this was not observed in canopies either shielded from UV or from PAR. The bleached first layer of the canopies acts as a selective UV-B filter, and thus prevents subcanopy thalli from exposure to harmful radiation. This was confirmed by the differences in photosynthetic activity, pigment composition, and the concentration of RubisCO in thalli with different positions within the canopy. In addition, the induction of the stress protein CPN 60 under UV exposure and the low accumulation of DNA damage indicate the presence of physiological protection mechanisms against harmful UV-B. A

  1. The effects of UV-B radiation on loblolly pine. 3. Interaction with CO2 enhancement

    International Nuclear Information System (INIS)

    Projected depletions in the stratospheric ozone layer will result in increases in solar ultraviolet-B radiation (290–320 nm) reaching the earth's surface, These increases will likely occur in concert with other environmental changes such as increases in atmospheric carbon dioxide concentrations. Currently very little information is available on the effectiveness of UV-B radiation within a CO2-enriched atmosphere, and this is especially true for trees. Loblolly pine (Pinus taeda L.) seedlings were grown in a factorial experiment at the Duke University Phytotron with either 0, 8.8 or 13.8 kJ m−2 of biologically effective UV-B radiation (UV-BBE). The CO2 concentrations used were 350 and 650 μmol mol−1. Measurements of chlorophyll fluorescence were made at 5-week intervals and photosynthetic oxygen evolution and leaf pigments were measured after 22 weeks, prior to harvest. The results of this study demonstrated a clear growth response to CO2 enrichment but neither photosynthetic capacity nor quantum efficiency were altered by CO2. The higher UV-B irradiance reduced total biomass by about 12% at both CO2 levels but biomass partitioning was altered by the interaction of CO2 and UV-B radiation. Dry matter was preferentially allocated to shoot components by UV-B radiation at 350 μmol mol−1 CO2 and towards root components at 650 μmol mol−1 CO2. These subtle effects on biomass allocation could be important in the future to seedling establishment and competitive interactions in natural as well as agricultural communities

  2. Effects of silicon application on diurnal variations of physiological properties of rice leaves of plants at the heading stage under elevated UV-B radiation

    Science.gov (United States)

    Lou, Yun-sheng; Wu, Lei; Lixuan, Ren; Meng, Yan; Shidi, Zhao; Huaiwei, Zhu; Yiwei, Zhang

    2016-02-01

    We investigated the effects of silicon (Si) application on diurnal variations of photosynthetic and transpiration physiological parameters in potted rice ( Oryza sativa L. cv Nanjing 45) at the heading stage. The plants were subjected to two UV-B radiation levels, i.e., reference UV-B (A, ambient, 12.0 kJ m-2 day-1) and elevated UV-B radiation (E, a 20 % higher dose of UV-B than the reference, 14.4 kJ m-2 day-1), and four Si application levels, i.e., Si0 (no silicon supplementation, 0 kg SiO2 ha-1), Si1 (sodium silicate, 100 kg SiO2 ha-1), Si2 (sodium silicate, 200 kg SiO2 ha-1), and Si3 (slag silicon fertilizer, 200 kg SiO2 ha-1). Compared with the reference, elevated UV-B radiation decreased the diurnal mean values of the net photosynthetic rate ( Pn), intercellular carbon dioxide (CO2) concentration ( Ci), transpiration rate ( Tr), stomatal conductivity ( Gs), and water use efficiency (WUE) by 11.3, 5.5, 10.4, 20.3, and 6.3 %, respectively, in plants not supplemented with silicon (Si0), and decreased the above parameters by 3.8-5.5, 0.7-4.8, 4.0-8.7, 7.4-20.2, and 0.7-5.9 %, respectively, in plants treated with silicon (Si1, Si2, and Si3), indicating that silicon application mitigates the negative effects of elevated UV-B radiation. Under elevated UV-B radiation, silicon application (Si1, Si2, and Si3) increased the diurnal mean values of Pn, Ci, Gs, and WUE by 16.9-28.0, 3.5-14.3, 16.8-38.7, and 29.0-51.2 %, respectively, but decreased Tr by 1.9-10.8 %, compared with plants not treated with silicon (E+Si0), indicating that silicon application mitigates the negative effects of elevated UV-B radiation by significantly increasing the P n, C i, G s, and WUE and decreasing the T r of rice. Evident differences existed in mitigating the depressive effects of elevated UV-B radiation on diurnal variations of physiological parameters among different silicon application treatments, exhibiting as Si3>Si2>Si1>Si0. In addition to recycling steel industrial wastes, the

  3. Differential flavonoid response to enhanced UV-B radiation in Brassica napus

    International Nuclear Information System (INIS)

    We have examined the qualitative and quantitative differences in methanol-soluble flavonoids of leaves of two cultivars of Brassica napus, which were grown with or without (control) supplemental UV-B radiation. The flavonoids were identified using HPLC-diode array spectroscopy (-DAS), -electrospray ionization-mass spectroscopy (-ESI-MS) and 1H and 13C NMR, and quantitatively analysed by HPLC-DAS. After exposure to supplementary UV-B radiation, the overall amount of soluble flavonoids, kaempferol and quercetin glycosides, increased by ca 150% in cv. Paroll, compared to control plants. Cultivar Stallion showed a 70% increase, and also a lower overall content of soluble flavonoids compared to Paroll. The supplementary UV-B radiation resulted in a marked, specific increase in the amount of quercetin glycosides relative to the kaempferol glycosides with a 36- and 23-fold increase in cvs Paroll and Stallion, respectively. Four of the flavonol glycosides appearing after supplemental UV-B exposure were identified as quercetin- and kaempferol 3-sophoroside-7-glucoside and 3-(2″′-E-sinapoylsophoroside)-7-glucoside. (author)

  4. The impact of UV-B radiation and ozone on terrestrial vegetation

    International Nuclear Information System (INIS)

    Although terrestrial vegetation has been exposed to UV-B radiation and ozone over the course of evolutionary history, it is essential to view the effects on vegetation of changing levels of these factors in the context of other features of climate change, such as increasing CO(2) levels and changes in temperature and precipitation patterns. Much of our understanding of the impacts of increased UV-B and ozone levels has come from studies of the effects of each individual factor. While such information may be relevant to a wider understanding of the roles that these factors may play in climate change, experience has shown that the interactions of environmental stresses on vegetation are rarely predictable. A further limitation on the applicability of such information results from the methodologies used for exposing plants to either factor. Much of our information comes from growth chamber, greenhouse or field studies using experimental protocols that made little or no provision for the stochastic nature of the changes in UV-B and ozone levels at the earth's surface, and hence excluded the roles of repair mechanisms. As a result, our knowledge of dose-response relationships under true field conditions is both limited and fragmentary, given the wide range of sensitivities among species and cultivars. Adverse effects of increased levels of either factor on vegetation are qualitatively well established, but the quantitative relationships are far from clear. In both cases, sensitivity varies with stage of plant development. At the population and community levels, differential responses of species to either factor has been shown to result in changes in competitiveness and community structure. At the mechanistic level, ozone generally inhibits photosynthetic gas exchange under both controlled and field conditions, and although UV-B is also inhibitory in some species under controlled conditions, others appear to be indifferent, particularly in the field. Both factors affect

  5. Effects of increasing UV-B radiation and atmospheric CO2 on photosynthesis and growth: implications for terrestrial ecosystems

    International Nuclear Information System (INIS)

    Increases in UV-B radiation reaching the earth as a result of stratospheric ozone depletion will most likely accompany increases in atmospheric CO2 concentrations. Many studies have examined the effects of each factor independently, but few have evaluated the combined effects of both UV-B radiation and elevated CO2. In general the results of such studies have shown independent effects on growth or seed yield. Although interspecific variation is large, high levels of UV-B radiation tends to reduce plant growth in sensitive species, while CO2 enrichment tends to promote growth in most C3 species. However, most previous studies have not looked at temporal effects or at the relationship between photosynthetic acclimation to CO2 and possible photosynthetic limitations imposed by UV-B radiation. Elevated CO2 may provide some protection against UV-B for some species. In contrast, UV-B radiation may limit the ability to exploit elevated CO2 in other species. Interactions between the effects of CO2 enrichment and UV-B radiation exposure have also been shown for biomass allocation. Effects on both biomass allocation and photosynthetic acclimation may be important to ecosystem structure in terms of seedling establishment, competition and reproductive output. Few studies have evaluated ecosystem processes such as decomposition or nutrient cycling. Interactive effects may be subtle and species specific but should not be ignored in the assessment of the potential impacts of increases in CO2 and UV-B radiation on plants. (author)

  6. Inactivation of bacteriophage infecting Bacteroides strain GB124 using UV-B radiation.

    Science.gov (United States)

    Diston, David; Ebdon, James E; Taylor, Huw D

    2014-01-01

    Ultraviolet-B radiation (280-320 nm) has long been associated with the inactivation of microorganisms in the natural environment. Determination of the environmental inactivation kinetics of specific indicator organisms [used as tools in the field of microbial source tracking (MST)] is fundamental to their successful deployment, particularly in geographic regions subject to high levels of solar radiation. Phage infecting Bacteroides fragilis host strain GB124 (B124 phage) have been demonstrated to be highly specific indicators of human fecal contamination, but to date, little is known about their susceptibility to UV-B radiation. Therefore, B124 phage (n = 7) isolated from municipal wastewater effluent, were irradiated in a controlled laboratory environment using UV-B collimated beam experiments. All B124 phage suspensions possessed highly similar first order log-linear inactivation profiles and the mean fluence required to inactivate phage by 4 - log(10) was 320 mJ cm(-2). These findings suggest that phage infecting GB124 are likely to be inactivated when exposed to the levels of UV-B solar radiation experienced in a variety of environmental settings. As such, this may limit the utility of such methods for determining more remote inputs of fecal contamination in areas subject to high levels of solar radiation.

  7. Interactive effects of ozone and low UV-B radiation on antioxidants in spruce (Picea abies) and pine (Pinus sylvestris) needles

    International Nuclear Information System (INIS)

    To study the role of low UV-B radiation in modulating the response of antioxidants to ozone, 4-year-old pine (Pinus sylvestris L.) and spruce (Picea abies L.) seedlings potted in natural soil, were exposed in phytochambers to fluctuating ozone concentrations between 9 and 113 nl 1−1 according to field data recorded at Mt Wank (1175 m above sea level, Bavaria, Germany) and two-times ambient O3 levels. UV-B radiation was either added at a biologically effective level of ca 1.2 kJ m−2 day−1 , which is close to that found in March at Mt Wank, or was excluded by filters (<0.08 kJ m−2 day−1). After one growth phase current-year needles were collected and analysed for antioxidative enzyme activities (superoxide dismutase, SOD, EC 1.15.1.1; catalase, CAT, EC 1.11.1.6; guaiacol peroxidase, POD, EC 1.11.1.7) and soluble antioxidants (ascorbate, glutathione). CAT, POD, ascorbate and glutathione, but not SOD, were increased in needles of both species in response to twice ambient O3 levels. UV-B radiation in the presence of ambient O3 caused an increase in total SOD activity in spruce but had no effects on antioxidants in pine. Twice ambient O3 levels together with low UV-B radiation counteracted the O3-induced increases in ascorbate and CAT in pine but not in spruce. Under these conditions spruce needles showed the highest antioxidative protection and revealed no indication of lipid peroxidation. Pine needles exposed to UV-B and elevated O3 levels showed elevated lipid peroxidation and a 5-fold increase in dehydroascorbate, suggesting that this species was less protected and suffered higher oxidative stress than spruce. (author)

  8. Effects of Enhanced UV-B Radiation on the Activity and Expression of Alternative Oxidase in Red Kidney Bean Leaves

    Institute of Scientific and Technical Information of China (English)

    Ming-Guang Zhao; Ying-Gao Liu; Li-Xin Zhang; Lin Zheng; Yu-Rong Bi

    2007-01-01

    An increase in ultraviolet (UV) B radiation on the earth's surface is a feature of current global climate changes. It has been reported that alternative oxidase (AOX) may have a protective role against oxidative stress induced by environmental stresses, such as UV-B. To better understand the characteristic tolerance of plants to UV-B radiation, the effects of enhanced UV-B radiation on the activity and expression of AOX in red kidney bean (Phaseolus vulgaris) leaves were investigated in the present study. The results show that the total respiration rate and AOX activity in red kidney bean leaves increased significantly during treatment with enhanced UV-B. However, cytochrome oxidase (COX) activity did not change at 24 h of UV-B treatment, before dropping rapidly. Both alternative pathway content and alternative pathway activity were increased in the presence of exogenous H2O2. Immunoblotting analysis with anti-AOX monoclonal antibody revealed that expression of the AOX protein increased in red kidney bean leaves under enhanced UV-B radiation, reaching a peak at 72increase in AOX activity in red kidney bean leaves under enhanced UV-B radiation was mainly due to H2O2-induced AOX expression.

  9. Observations of UV-B radiation during biomass burning at cuiabá, Brazil

    Science.gov (United States)

    Sahai, Y.; Kirchhoff, V. W. J. H.; Paes Leme, N.; Casiccia, C.

    During the last few years, a network (6 stations) of Brewer spectrophotometers has been established in different ecosystems in South America by the Brazilian National Institute for Space Research (INPE). A Brewer spectrophotometer permits simultaneous observations of total ozone and UV-B radiation and is operational on a routine basis at Cuiabá (16°S, 56°W), Brazil, since 1991. Surface ozone is also measured at Cuiabá using UV ozone monitor since 1987. In this paper we present and discuss the simultaneous observations from these two instruments obtained in 1995. This study permits comparison of the observations during the biomas burning period (dry season) with the wet season. Although surface ozone levels were considerably higher during the biomass burning season, no effect on the total ozone column could be observed. The UV-B radiation, however, was significantly reduced due to absorption by biomass burning aerosols.

  10. Effect of UV-B Radiation (290-320nm) on the Nitrogen Metabolism of Several Marine Diatoms.

    Science.gov (United States)

    Döhler, G

    1985-04-01

    The marine diatoms Bellerochea yucatanensis, Biddulphia sinensis, Ditylum brightwellii, Lauderia annulata and Thalassiosira rotula were grown for 2 days under different levels of UV-B radiation (439, 717, and 1230J · m (-2) ·d(-1)). UV-B stress depressed the growth rates of all species. A low UV-B dose (439 J · m (-2) · d (-1), weighted), usually caused a slight increase in biomass production (dry weight} in comparison to nontreated cells. Enhanced UV-B reduced the dry matter productivity of all diatoms. All marine diatoms exposed to UV-B showed a diminution of protein and pigment content (chlorophyll a, chlorophyll c(1) + C(2), and carotenoids). Algae grown in 20 %o or 35 %o salt concentrations were more sensitive to UV-B radiation than those grown in 45%o. S. The effect of higher UV-B dose (717J · m (-2) · d(-1), weighted) upon the pools of free amino acids was species-dependent. Aspartate and asparagine levels were reduced in all diatoms. A marked increase in glutamine levels was found in Bellerochea, Biddulphia, Ditylum and Lauderia. Thalassiosira cells exposed to UV-B showed a significant increase in glutamate levels and a reduction of glutamine levels. (15)N and (14)C incorporation into several amino acids was reduced by exposure to UV-B. The results are discussed with reference to the inhibition of the enzymes for carbon and nitrogen metabolism. PMID:23196172

  11. Mediated modeling of the impacts of enhanced UV-B radiation on ecosystem services.

    Science.gov (United States)

    van den Belt, Marjan; Bianciotto, Oscar A; Costanza, Robert; Demers, Serge; Diaz, Susana; Ferreyra, Gustavo A; Koch, Evamaria W; Momo, Fernando R; Vernet, Maria

    2006-01-01

    This article describes the use of group model building to facilitate interaction with stakeholders, synthesize research results and assist in the development of hypotheses about climate change at the global level in relation to UV-B radiation and ecosystem service valuation. The objective was to provide a platform for integration of the various research components within a multidisciplinary research project as a basis for interaction with stakeholders with backgrounds in areas other than science. An integrated summary of the scientific findings, along with stakeholder input, was intended to produce a bridge between science and policymaking. We used a mediated modeling approach that was implemented as a pilot project in Ushuaia, Argentina. The investigation was divided into two participatory workshops: data gathering and model evaluation. Scientists and the local stakeholders supported the valuation of ecosystem services as a useful common denominator for integrating the various scientific results. The concept of economic impacts in aquatic and marsh systems was represented by values for ecosystem services altered by UV-B radiation. In addition, direct local socioeconomic impacts of enhanced UV-B radiation were modeled, using data from Ushuaia. We worked with 5 global latitudinal regions, focusing on net primary production and biomass for the marine system and on 3 plant species for the marsh system. Ecosystem service values were calculated for both sectors. The synthesis model reflects the conclusions from the literature and from experimental research at the global level. UV-B is not a significant stress for the marshes, relative to the potential impact of increases in the sea level. Enhanced UV-B favors microbial dynamics in marine systems that could cause a significant shift from primary producers to bacteria at the community level. In addition, synergetic effects of UV-B and certain pollutants potentiate the shift to heterotrophs. This may impact the oceanic

  12. Mediated modeling of the impacts of enhanced UV-B radiation on ecosystem services.

    Science.gov (United States)

    van den Belt, Marjan; Bianciotto, Oscar A; Costanza, Robert; Demers, Serge; Diaz, Susana; Ferreyra, Gustavo A; Koch, Evamaria W; Momo, Fernando R; Vernet, Maria

    2006-01-01

    This article describes the use of group model building to facilitate interaction with stakeholders, synthesize research results and assist in the development of hypotheses about climate change at the global level in relation to UV-B radiation and ecosystem service valuation. The objective was to provide a platform for integration of the various research components within a multidisciplinary research project as a basis for interaction with stakeholders with backgrounds in areas other than science. An integrated summary of the scientific findings, along with stakeholder input, was intended to produce a bridge between science and policymaking. We used a mediated modeling approach that was implemented as a pilot project in Ushuaia, Argentina. The investigation was divided into two participatory workshops: data gathering and model evaluation. Scientists and the local stakeholders supported the valuation of ecosystem services as a useful common denominator for integrating the various scientific results. The concept of economic impacts in aquatic and marsh systems was represented by values for ecosystem services altered by UV-B radiation. In addition, direct local socioeconomic impacts of enhanced UV-B radiation were modeled, using data from Ushuaia. We worked with 5 global latitudinal regions, focusing on net primary production and biomass for the marine system and on 3 plant species for the marsh system. Ecosystem service values were calculated for both sectors. The synthesis model reflects the conclusions from the literature and from experimental research at the global level. UV-B is not a significant stress for the marshes, relative to the potential impact of increases in the sea level. Enhanced UV-B favors microbial dynamics in marine systems that could cause a significant shift from primary producers to bacteria at the community level. In addition, synergetic effects of UV-B and certain pollutants potentiate the shift to heterotrophs. This may impact the oceanic

  13. Protective effect of UV-A radiation during acclimation of the photosynthetic apparatus to UV-B treatment.

    Science.gov (United States)

    Štroch, Michal; Materová, Zuzana; Vrábl, Daniel; Karlický, Václav; Šigut, Ladislav; Nezval, Jakub; Špunda, Vladimír

    2015-11-01

    We examined the acclimation response of the photosynthetic apparatus of barley (Hordeum vulgare L.) to a combination of UV-A and UV-B radiation (UVAB) and to UV-B radiation alone. Our aim was to evaluate whether UV-A radiation prevents UV-B-induced damage to the photosynthetic apparatus and whether UV-A pre-acclimation is required to mitigate the negative influence of UV-B radiation. Barley plants were grown from seeds under low photosynthetically active radiation (50 μmol m(-2) s(-1)) either in the absence or presence of UV-A radiation (UVA- and UVA+ plants, respectively). After 8 days of development, plants were exposed simultaneously to UV-A and UV-B radiation for the next 6 days. Additionally, UVA- plants were exposed to UV-B radiation alone. The UVA+ plants had a higher CO2 assimilation rate near the light-saturation region (A(N)) and a higher content of both total chlorophylls (Chls) and total carotenoids than the UVA- plants. Chls content, A(N), the potential quantum yield of photosystem II (PSII) photochemistry (F(V)/F(M)), the capacity of light-induced thermal energy dissipation and the efficiency of excitation energy transfer within PSII remained the same or even increased in both UVA+ and UVA- plants after UVAB treatment. On the contrary, exposure of UVA- plants to UV-B radiation itself led to a reduction in all these characteristics. We revealed that the presence of UV-A radiation during UVAB treatment not only mitigated but completely eliminated the negative effect of UV-B radiation on the functioning of the photosynthetic apparatus and that UV-A pre-acclimation was not crucial for development of this UV-A-induced resistance against UV-B irradiation. PMID:26233710

  14. Does enhanced solar UV-B radiation affect marine primary producers in their natural habitats?

    Science.gov (United States)

    Häder, Donat-P

    2011-01-01

    This article is a highlight of the paper by Li et al. in this issue of Photochemistry and Photobiology as well as a short summary of the research on the effects of solar UV-B radiation on primary production in the oceans. Laboratory experiments under controlled conditions using artificial light sources indicate species-specific damage of many phytoplankton groups. Mesocosm studies in enclosures of limited volume allow analyzing UV effects in multigeneration monitoring of natural assemblages. Field studies to determine the effects of short-wavelength solar radiation require sensitive instrumentation and measurements over extended areas of the open ocean to yield significant results. Results from a cruise described in the paper by Li et al. indicate clear effects of UV-B and UV-A on the photosynthetic carbon fixation of phytoplankton communities with spatial differences between coastal and open-ocean waters. Increasing temperatures and acidification in the ocean due to global climate change may exacerbate the detrimental effects of solar UV-B radiation. PMID:21208211

  15. Arctic microorganisms respond more to elevated UV-B radiation than CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D.; Lee, J.A. [University of Sheffield (United Kingdom). Dept. of Animal and Plant Sciences; Campbell, C.D. [The Macaulay Land Use Research Institute, Aberdeen (United Kingdom); Callaghan, T.V. [Abisko Scientific Research Station, Abisko (Sweden); Gwynn-Jones, D. [University of Wales, Aberystwyth (United Kingdom). Institute of Biological Sciences

    2002-07-01

    Surface ultraviolet-B radiation and atmospheric CO{sub 2} concentrations have increased as a result of ozone depletion and burning of fossil fuels. The effects are likely to be most apparent in polar regions where ozone holes have developed and ecosystems are particularly sensitive to disturbance. Polar plant communities are dependent on nutrient cycling by soil microorganisms, which represent a significant and highly labile portion of soil carbon (C) and nitrogen (N). It was thought that the soil microbial biomass was unlikely to be affected by exposure of their associated plant communities to increased UV-B. In contrast, increasing atmospheric CO{sub 2} concentrations were thought to have a strong effect as a result of greater below-ground C allocation. In addition, there is a growing belief that ozone depletion is of only minor environmental concern because the impacts of UV-B radiation on plant communities are often very subtle. Here we show that 5 years of exposure of a subarctic heath to enhanced UV-B radiation both alone and in combination with elevated CO{sub 2} resulted in significant changes in the C:N ratio and in the bacterial community structure of the soil microbial biomass. (author)

  16. Enhanced resistance to UV-B radiation in Anabaena sp. PCC 7120 (Cyanophyceae) by repeated exposure.

    Science.gov (United States)

    Qin, Hongjie; Li, Dunhai

    2014-07-01

    In natural habitats, organisms especially phytoplankton are not always continuously subjected to ultraviolet-B radiation (UVBR). By simulation of the natural situation, the N2-fixing cyanobacterium Anabaena sp. PCC 7120 was subjected to UV-B exposure and recovery cycles. A series of morphological and physiological changes were observed in Anabaena sp. PCC 7120 under repeated UVBR when compared with controls. Such as the breakage of filaments, intervals between heterocysts, heterocyst frequency, total carbohydrate, and carotenoids were increased, while the nitrogenase activity and photosynthetic activity were inhibited by repeated UVBR; however, these activities could recover when UV-B stress was removed. Unexpectedly, the over-compensatory growth was observed at the end of the second round of exposure and recovery cycle. Our results showed that discontinuous UVBR could increase the growth rate and the tolerance as well as repair capacity of Anabaena sp. PCC 7120. These results indicate that moderate UVBR may increase the growth of cyanobacteria in natural habitats.

  17. Effects of enhanced UV-B radiation on pea (Pisum sativum L.) grown under field conditions in the UK

    International Nuclear Information System (INIS)

    A new modulated lamp system is described. This system has successfully provided an ultraviolet-B (UV-B) supplement in proportion to ambient UV-B. The modulated system was used to simulate the UV-B environment resulting from an annual mean reduction of 15% in the stratospheric ozone under UK field conditions, but taking account of seasonal variation in depletion. The effects of this enhanced level of UV-B on the growth, physiology and yield of four cultivars of pea were assessed. Enhanced UV-B resulted in small reductions in the number of stems and total stem length per plant (respectively 4.7 and 8.7%). There were also significant decreases in the dry weight of peas (10.1%), pods (10.3%) and stems (7.8%) per plant. UV-B treatment had no effect on the number of peas per pod or average pea weight, but did significantly reduce (12.1%) the number of pods per plant. This decrease in pod number was partly due to enhanced abscission of pods during the final month of plant growth. UV-B treatment had no significant effect on chlorophyll fluorescence characteristics or CO2 assimilation rate per unit leaf area. These results are consistent with previous controlled environment experiments, and suggest that reduction in yield may be due to direct effects of UV-B on plant growth rather than a decrease in photosynthetic capacity per unit leaf area. (author)

  18. Effects of ozone depletion and UV-B radiation on humans and the environment

    Energy Technology Data Exchange (ETDEWEB)

    Solomon, K.R. [Guelph Univ., ON (Canada). Centre for Toxicology

    2008-03-15

    This paper summarized current research related to the effects of ultraviolet (UV-B) radiation on human health and the environment. Effects included direct responses in human as well as effects on biogeochemistry and the environmental cycling of substances. UV radiation has many harmful effects on the skin, eyes, and immune systems of humans. Skin cancer is a leading cause of death among fair-skinned populations exposed to UV radiation. The role of UV radiation in cataract formation was discussed, as well as issues related to the suppression of immune responses. The link between sunlight exposure and vitamin D levels in human populations was examined. The effects of UV radiation on terrestrial and aquatic ecosystems were reviewed. Issues related to biogeochemistry and atmospheric processes were discussed. The review suggested that changes in the intensity of solar UV radiation due to ozone depletion will have important repercussions for all organisms on the planet. It was concluded that the combined effects of UV-B radiation and climate change will not be easy to predict. 201 refs., 4 figs.

  19. Above- and below-ground responses of Calamagrostis purpurea to UV-B radiation and elevated CO{sub 2} under phosphorus limitation

    Energy Technology Data Exchange (ETDEWEB)

    Bussell, J.S.; Gwynn-Jones, D.; Griffith, G.W.; Scullion, J. (Aberystwyth Univ., IBERS, Wales (United Kingdom))

    2012-08-15

    UV-B radiation and elevated CO{sub 2} may impact rhizosphere processes through altered below-ground plant resource allocation and root exudation, changes that may have implications for nutrient acquisition. As nutrients limit plant growth in many habitats, their supply may dictate plant response under elevated CO{sub 2}. This study investigated UV-B exposure and elevated CO{sub 2} effects, including interactions, on plant growth, tissue chemistry and rooting responses relating to P acquisition. The sub-arctic grass Calamagrostis purpurea was subjected to UV-B (0 or 3.04 kJ m-2day-1) and CO{sub 2} (ambient 380 or 650 ppmv) treatments in a factorial glasshouse experiment, with sparingly soluble P (0 or 0.152 mg P per plant as FePO{sub 4}) a further factor. It was hypothesized that UV-B exposure and elevated CO{sub 2} would change plant resource allocation, with CO{sub 2} mitigating adverse responses to UV-B exposure and aiding P uptake. Plant biomass and morphology, tissue composition and rhizosphere leachate properties were measured. UV-B directly affected chemical composition of shoots and interacted with CO{sub 2} to give a greater root biomass. Elevated CO{sub 2} altered the composition of both shoots and roots and increased shoot biomass and secondary root length, while leachate pH decreased. Below-ground responses to CO{sub 2} did not affect P acquisition although P limitation progressively reduced leachate pH and increased secondary root length. Although direct plant growth, foliar composition and below-ground nutrient acquisition responses were dominated by CO{sub 2} treatments, UV-B modified these CO{sub 2} responses significantly. These interactions have implications for plant responses to future atmospheric conditions. (Author)

  20. Multilevel UV-B Attenuance : Morphological and Chemical Adaptations of Vicia faba to Ultraviolet-B Radiation

    OpenAIRE

    Meijkamp, B.B.

    2006-01-01

    Due to anthropogenic reduction of stratospheric ozone, levels of potentially harmful solar UV-B radiation (280-315 nm) have been increasing on earth during the last three decades. The main aim of this thesis was to study growth responses and morphological and chemical adaptation mechanisms to harmful UV-B radiation. Two cultivars of Vicia faba, differing in UV-B sensitivity were used as a model system. Constitutive defence mechanisms appeared to function very well; even in the sensitive cv. P...

  1. Dynamics of anthocyanin in aging of ipomea purpurea flowers treated by uv-b radiation

    OpenAIRE

    Анастасія Миколаївна Берестяна

    2014-01-01

    The dynamics of the anthocyanin content reduction in the course of aging of the Ipomoea purpureа petals, which characterizes the rate of the degradation processes in a cell, has been studied. The analysis included the impact of various UV-B radiation doses on the rate of anthocyanin age-related decomposition. The experiment proved that but one dose – 12.6 kJ/m2 contributed to the deceleration of the anthocyanin decomposition rate, within the range studied. The probable mechanisms that connect...

  2. Dynamics of anthocyanin in aging of ipomea purpurea flowers treated by uv-b radiation

    Directory of Open Access Journals (Sweden)

    Анастасія Миколаївна Берестяна

    2014-10-01

    Full Text Available The dynamics of the anthocyanin content reduction in the course of aging of the Ipomoea purpureа petals, which characterizes the rate of the degradation processes in a cell, has been studied. The analysis included the impact of various UV-B radiation doses on the rate of anthocyanin age-related decomposition. The experiment proved that but one dose – 12.6 kJ/m2 contributed to the deceleration of the anthocyanin decomposition rate, within the range studied. The probable mechanisms that connect ageing and pigment degradation are being discussed. 

  3. P1 Epigenetic Regulation in Leaves of High Altitude Maize Landraces: Effect of UV-B Radiation

    Science.gov (United States)

    Rius, Sebastián P.; Emiliani, Julia; Casati, Paula

    2016-01-01

    P1 is a R2R3-MYB transcription factor that regulates the accumulation of a specific group of flavonoids in maize floral tissues, such as flavones and phlobaphenes. P1 is also highly expressed in leaves of maize landraces adapted to high altitudes and higher levels of UV-B radiation. In this work, we analyzed the epigenetic regulation of the P1 gene by UV-B in leaves of different maize landraces. Our results demonstrate that DNA methylation in the P1 proximal promoter, intron1 and intron2 is decreased by UV-B in all lines analyzed; however, the basal DNA methylation levels are lower in the landraces than in B73, a low altitude inbred line. DNA demethylation by UV-B is accompanied by a decrease in H3 methylation at Lys 9 and 27, and by an increase in H3 acetylation. smRNAs complementary to specific regions of the proximal promoter and of intron 2 3′ end are also decreased by UV-B; interestingly, P1 smRNA levels are lower in the landraces than in B73 both under control conditions and after UV-B exposure, suggesting that smRNAs regulate P1 expression by UV-B in maize leaves. Finally, we investigated if different P1 targets in flower tissues are also regulated by this transcription factor in response to UV-B. Some targets analyzed show an induction in maize landraces in response to UV-B, with higher basal expression levels in the landraces than in B73; however, not all the transcripts analyzed were found to be regulated by UV-B in leaves. PMID:27148340

  4. Effect of enhanced UV-B radiation on methane emission in a paddy field and rice root exudation of low-molecular-weight organic acids.

    Science.gov (United States)

    He, Yongmei; Zhan, Fangdong; Li, Yuan; Xu, Weiwei; Zu, Yanqun; Yue, Ming

    2016-06-01

    A local rice variety, "Baijiaolaojing", was grown in a paddy field in the Yuanyang rice terraces under ambient and supplemental levels of ultraviolet-B (UV-B, 280-315 nm) radiation. The effects of enhanced UV-B radiation (5 and 10 kJ m(-2) d(-1)) on methane emissions in the paddy field were evaluated using a closed-chamber gas chromatography-based system, and the contents of low-molecular-weight organic acids (LMWOAs) in root exudates were determined by high-performance liquid chromatography (HPLC). Peaks in methane emissions in the paddy field were detected at 60, 80 and 100 days after rice transplantation. The highest level of cumulative methane emissions occurred at the tillering stage, followed by the jointing-booting and maturity stages. The lowest level was found at the flowering stage. The enhanced UV-B radiation did not change the seasonal variation in methane emissions in the paddy field; however, it induced a significant increase in the flux of methane emissions at the jointing-booting and maturity stages, as well as a significant increase in the cumulative flux of methane emissions throughout the growth period. In addition, the enhanced UV-B radiation caused an increase in the contents of oxalic acid and succinic acid and a decrease in the contents of tartaric acid and malic acid in rice root exudates. Furthermore, a significant positive correlation (r = 0.725, p oxalic acid and the methane emissions in the paddy field. The results indicated that enhanced UV-B radiation promoted methane emissions in the paddy field, which was closely associated with its impact on the exudation of LMWOAs by rice roots. PMID:27194164

  5. Effect of UV-B radiation (290-320 nm) on the nitrogen metabolism of several marine diatoms

    Energy Technology Data Exchange (ETDEWEB)

    Doehler, G.

    1985-01-01

    The marine diatoms Bellerochea yucatanensis, Biddulphia sinensis, Ditylum brightwellii, Lauderia annulata and Thalassiosira rotula were grown for 2 days under different levels of UV-B radiation (439, 717, and 1230 J . m/sup -2/ . d/sup -1/). UV-B stress depressed the growth rates of all species. A low UV-B dose (439 J . m/sup -2/ . d/sup -1/, weighted), usually caused a slight increase in biomass production (dry weight) in comparison to nontreated cells. Enhanced UV-B reduced the dry matter productivity of all diatoms. All marine diatoms exposed to UV-B showed a diminution of protein and pigment content (chlorophyll a, chlorophyll c/sub 1/ + c/sub 2/, and carotenoids). Algae grown in 20per mille or 35per mille salt concentrations were more sensitive to UV-B radiation than those grown in 45per mille S. The effect of higher UV-B dose (717 J . m/sup -2/ . d/sup -1/, weighted) upon the pools of free amino acids was species-dependent. Aspartate and asparagine levels were reduced in all diatoms. A marked increase in glutamine levels was found in Bellerochea, Biddulphia, Ditylum and Lauderia. Thalassiosira cells exposed to UV-B showed a significant increase in glutamate levels and a reduction of glutamine levels. /sup 15/N and /sup 14/C incorporation into several amino acids was reduced by exposure to UV-B. The results are discussed with reference to the inhibition of the enzymes for carbon and nitrogen metabolism.

  6. The nopaline synthase (nos) promoter is inducible by UV-B radiation through a pathway dependent on reactive oxygen species

    International Nuclear Information System (INIS)

    The molecular mechanism of plant response to UV-B radiation was studied using the nopaline synthase (nos) promoter, which has been shown to be inducible by methyl jasmonate (MJ) and reactive oxygen species (ROS). In the leaves of transgenic tobacco (Nicotiana tabacum L.) plants that carried a fusion between the nos promoter and the chloramphenicol acetyltransferase (cat) gene, 2 h of UV-B treatment resulted in a transient increase in the level of cat mRNA, a maximum being reached at 6 h after the UV-B treatment. It was also found that MJ and UV-B enhance nos promoter expression via separate pathways. Diethyldithiocarbamic acid, a potent inhibitor of jasmonate production, had little effect on UV-B stimulation of the nos promoter. In contrast, antioxidants, such as dimethylthiourea, reduced glutathione, cysteine, N-acetylcysteine and DTT, blocked UV-B induction of the nos promoter, but did not affect MJ induction of the nos promoter. These results suggest that UV-B induction of the nos promoter is mediated via a pathway that requires reactive oxygen species and is distinct from the jasmonate or MJ mediating pathway. (author)

  7. UV-B辐射对马尾松凋落叶分解和养分释放的影响%Effect of UV-B radiation on the leaf litter decomposition and nutrient release of Pinus massoniana

    Institute of Scientific and Technical Information of China (English)

    宋新章; 张慧玲; 江洪; 余树全; 张智婷

    2011-01-01

    lamps and removing most of the solar UV-B reaching sample through the mylar filters are the two most common approaches when attempting to simulate and test the effects of enhanced UV-B levels associated with ozone depletion.Most of the studies were conducted in the Northern Hemisphere using UV-B lamps systems to stimulate enhanced UV-B conditions.But an unrealistic balance between UV-B, UV-A (315 -400 nm), and visible (400 -700 nm) radiation may exaggerate the effects of UV-B.Exclusion of solar UV-B through the use of mylar filters that absorb most of the incident solar UV-B provides a relatively simple mean to compare the influences of the current enhanced UV-B level vs.lower levels in the past.The ozone change is also taking place in subtropical China with an average annual depletion of 0.27%.The effect of UV-B radiation on litter decomposition of woody plant was poorly understood especially in China.The leaf litter decomposition of Pinus massoniana, which is a common coniferous species in subtropical China, under ambient and reduced (by 22% under ambient) UV-B radiation conditions by filtering existing solar radiation with mylar filters was investigated with litterbag method during 12 months experiment in this study.The aim of our study is to assess the effect of the changes in UV-B radiation on leaf litter decomposition, lignin degradation, and nutrient (N, P and K ) release from P.massoniana.The results showed that the leaf litter decomposition rate slowed 47.74% under reduced UV-B radiation than that under ambient UV-B.UV-B radiation is very significantly accelerated the leaf litter decomposition of P.massoniana (p<0.01), and promoted the release of P, K, C and lignin degradation, but had no obvious effect on release of N.The results indicated that UV-B radiation would speed up the nutrient cycle in P.massoniana forest and decrease the carbon store in litter layer of P.massoniana forest.%由大气臭氧层减薄导致的UV-B辐射变化将直接影响到

  8. Short-term UV-B radiation affects photosynthetic performance and antioxidant gene expression in highbush blueberry leaves.

    Science.gov (United States)

    Inostroza-Blancheteau, Claudio; Acevedo, Patricio; Loyola, Rodrigo; Arce-Johnson, Patricio; Alberdi, Miren; Reyes-Díaz, Marjorie

    2016-10-01

    The impact of increased artificial UV-B radiation on photosynthetic performance, antioxidant and SOD activities and molecular antioxidant metabolism responses in leaves of two highbush blueberry (Vaccinium corymbosum L. cv. Brigitta and Bluegold) genotypes was studied. Plants were grown in a solid substrate and exposed to 0, 0.07, 0.12 and 0.19 W m(-2) of biologically-effective UV-B irradiance for 0-72 h. Our findings show that net photosynthesis (Pn) decreased significantly in Bluegold, accompanied by a reduction in the effective quantum yield (ФPSII) and electron transport rate (ETR), especially at the highest UV-B irradiation. On the other hand, Brigitta showed a better photosynthetic performance, as well as a clear increment in the antioxidant activity response that could be associated with increased superoxide dismutase activity (SOD) in the early hours of induced UV-B stress in all treatments. At the molecular level, the expression of the three antioxidant genes evaluated in both genotypes had a similar tendency. However, ascorbate peroxidase (APX) expression was significantly increased (6-fold) in Bluegold compared to Brigitta. Thus, the reduction of Pn concomitant with a lower photochemical performance and a reduced response of antioxidant metabolism suggest that the Bluegold genotype is more sensitive to UV-B radiation, while Brigitta appears to tolerate better moderate UV-B irradiance in a short-term experiment.

  9. Short-term UV-B radiation affects photosynthetic performance and antioxidant gene expression in highbush blueberry leaves.

    Science.gov (United States)

    Inostroza-Blancheteau, Claudio; Acevedo, Patricio; Loyola, Rodrigo; Arce-Johnson, Patricio; Alberdi, Miren; Reyes-Díaz, Marjorie

    2016-10-01

    The impact of increased artificial UV-B radiation on photosynthetic performance, antioxidant and SOD activities and molecular antioxidant metabolism responses in leaves of two highbush blueberry (Vaccinium corymbosum L. cv. Brigitta and Bluegold) genotypes was studied. Plants were grown in a solid substrate and exposed to 0, 0.07, 0.12 and 0.19 W m(-2) of biologically-effective UV-B irradiance for 0-72 h. Our findings show that net photosynthesis (Pn) decreased significantly in Bluegold, accompanied by a reduction in the effective quantum yield (ФPSII) and electron transport rate (ETR), especially at the highest UV-B irradiation. On the other hand, Brigitta showed a better photosynthetic performance, as well as a clear increment in the antioxidant activity response that could be associated with increased superoxide dismutase activity (SOD) in the early hours of induced UV-B stress in all treatments. At the molecular level, the expression of the three antioxidant genes evaluated in both genotypes had a similar tendency. However, ascorbate peroxidase (APX) expression was significantly increased (6-fold) in Bluegold compared to Brigitta. Thus, the reduction of Pn concomitant with a lower photochemical performance and a reduced response of antioxidant metabolism suggest that the Bluegold genotype is more sensitive to UV-B radiation, while Brigitta appears to tolerate better moderate UV-B irradiance in a short-term experiment. PMID:27343876

  10. Physiological Defense Mechanism of Ligularia intermedia Against UV-B Radiation on Dongling Mountain

    Institute of Scientific and Technical Information of China (English)

    李鑫; 贾顺姬; 简嘉; 林孟仪; 李骑昂; 黄晓春; 张超; 张荣庆; 张贵友

    2003-01-01

    Ligularia intermedia growing at different altitudes were used to investigate the mechanism of ultraviolet (UV)-resistance on physiological aspects in the field.The tests compared the absorbance of the UV-absorbing compound, the content of chlorophyll a, chlorophyll b, and carotenoids, and the activities of peroxidase (POX) and superoxide dismutase (SOD) in Ligularia intermedia growing at three different altitudes on Dongling Mountain in northern China.There were no significant differences between the plants growing at 1160 m and 1820 m.However, all of these factors increased dramatically at 2190 m.The results indicate that the UV-resistance of the plants mainly depends on the mechanism of filtering the radiation and preventing the reactive oxygen species (ROS) damage produced by UV-B.

  11. Aerosol radiative forcing efficiency in the UV-B region over central Argentina

    Science.gov (United States)

    Palancar, Gustavo G.; Olcese, Luis E.; Lanzaco, Bethania L.; Achad, Mariana; López, María Laura; Toselli, Beatriz M.

    2016-07-01

    AEROSOL Robotic Network (AERONET), Moderate Resolution Imaging Spectroradiometer (MODIS) and global UV-B (280-315 nm) irradiance measurements and calculations were combined to investigate the effects of aerosol loading on the ultraviolet B radiation (UV-B) reaching the surface under cloudless conditions in Córdoba, Argentina. The aerosol radiative forcing (ARF) and the aerosol forcing efficiency (ARFE) were calculated for an extended period of time (2000-2013) at a ground-based monitoring site affected by different types and loading of aerosols. The ARFE was evaluated by using the aerosol optical depth (AOD) at 340 nm retrieved by AERONET at the Cordoba CETT site. The individual and combined effects of the single scattering albedo (SSA) and the solar zenith angle (SZA) on the ARFE were also analyzed. In addition, and for comparison purposes, the MODIS AOD at 550 nm was used as input in a machine learning method to better characterize the aerosol load at 340 nm and evaluate the ARFE retrieved from AOD satellite measurements. The ARFE at the surface calculated using AOD data from AERONET ranged from (-0.11 ± 0.01) to (-1.76 ± 0.20) Wm-2 with an average of -0.61 Wm-2; however, when using AOD data from MODIS (TERRA/AQUA satellites), it ranged from (-0.22 ± 0.03) to (-0.65 ± 0.07) Wm-2 with an average value of -0.43 Wm-2. At the same SZA and SSA, the maximum difference between ground and satellite-based was 0.22 Wm-2.

  12. Long-term effects of elevated ozone and UV-B radiation on vegetation and methane dynamics in northern peatland ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Morsky, S.K.

    2012-06-15

    . However, the temporary decrease in CH{sub 4} emission was not consistent and towards the end of the experiment O{sub 3} tended to increase net CH{sub 4} emission. Enhanced UV-B radiation did not affect leaf anatomy or senescence rate of Eriophorum russeolum leaves. In addition, there were no UV-B effects on the total chlorophyll or carotenoid concentrations in E. russeolum leaves during the current study. UV-B radiation transiently increased the amount of cell wall bound UV-absorbing pigments in E. russeolum leaves. Organic acid concentrations in peat were slightly higher in the UV-B treatment compared to ambient control treatment. Elevated UV-B radiation did not reduce net CH{sub 4} emission during the three consecutive growing seasons nor did it affect wintertime CH{sub 4} emission rates. The results of this thesis indicate that almost doubled ambient O{sub 3} or moderately enhanced UV-B would not reduce vitality of peatland vegetation in the near future. However, these stress factors can change carbon allocation below ground, which would increase net CH{sub 4} emissions from northern peatlands in the longer term. (orig.)

  13. TiO2 nanoparticles as an effective UV-B radiation skin-protective compound in sunscreens

    International Nuclear Information System (INIS)

    Protecting human skin against harmful UV-B radiation coming from the sun is currently a problem. Due to the decreased thickness of the ozone layer, a more dangerous amount of UV-B light reaches the surface of our planet. This causes increased frequency of skin diseases. Titanium dioxide (TiO2) fine particles are embedded with sunscreens into the skin to effectively attenuate UV-B radiation. This study evaluates the most appropriate size of such particles assuming they are spheres. The distribution of TiO2 particles within the skin, achieved with topically applied sunscreens, is determined experimentally by the tape-stripping technique. Computer code implementing the Monte Carlo method is used to simulate photon migration within the plain 20 μm thick horny layer matrix partially filled with nano-sized TiO2 particles. Dependences of harmful UV-B radiation of 307-311 nm absorbed by, backscattered from and transmitted through the horny layer on the concentration of TiO2 particles are obtained and analysed. As a result, particles of 62 nm are found to be the most effective in protecting skin against UV-B light

  14. Effects of lanthanum(III) on nitrogen metabolism of soybean seedlings under elevated UV-B radiation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The hydroponic culture experiments of soybean bean seedlings were conducted to investigate the effect of lanthanum (La) on nitrogen metabolism under two different levels of elevated UV-B radiation (UV-B, 280-320 nm). The whole process of nitrogen metabolism involves uptake and transport of nitrate, nitrate assimilation, ammonium assimilation, amino acid biosynthesis, and protein synthesis. Compared with the control, UV-B radiation with the intensity of 0.15 W/m2 and 0.45 W/m2 significantly affected the whole nitrogen metabolism in soybean seedlings (p < 0.05). It restricted uptake and transport of NO3-, inhibited activity of some key nitrogen-metabolism-related enzymes such as nitrate reductase (NR) related to the nitrate reduction, as well as glutamine systhetase (GS) and glutamine synthase (GOGAT) related to the ammonia assimilation while it increased the content of free amino acids and decreased that of soluble protein as well. The damage effect of high level of UV-B radiation on nitrogen metabolism was greater than that of low one. And UV-B radiation promoted the activity of the anti-adversity enzyme glutamate dehydrogenase (GDH), which reduced the toxicity of excess ammonia in plant. After pretreatment with the optimum concentration of La (20 mg/L), La could increase the activity of NR, GS, GOGAT, and GDH, and ammonia assimilation, but decrease nitrate and ammonia accumulation. In conclusion, La could relieve the damage effect of UV-B radiation on plant by regulating nitrogen metabolism process, and its alleviating effect under low level was better than that under the high one.

  15. Effects of enhanced UV-B radiation on secondary metabolites in forage plants and potential consequences for multiple trophic responses involving mammalian herbivores

    Science.gov (United States)

    Thines, Nicole J.; Bassman, John H.; Shipley, Lisa A.; Slusser, James R.

    2004-10-01

    Herbivores represent the interface between primary production and higher trophic levels. The effects of enhanced UV-B radiation on microbes, invertebrate herbivores, and detritivores has received limited study in both terrestrial and aquatic ecosystems. However, although direct effects (e.g. melanoma, cataracts) on mammals have been documented, indirect effects (e.g., resulting from changes in plant chemistry) of enhanced UV-B on mammalian herbivores have not been evaluated. Although the diet of mammalian herbivores has little effect on nutritional quality for their associated predators, to the extent changes in plant chemistry affect aspects of population dynamics (e.g., growth, fecundity, densities), higher trophic levels can be affected. In this study, different forage species of varying inherent levels of key secondary metabolites are being grown in the field under either ambient or ambient plus supplemental UV-B radiation simulating a 15% stratospheric ozone depletion for Pullman, Washington. At various time intervals, foliage is being sampled and analyzed for changes in secondary metabolites and other attributes. Using controlled feeding trials, changes in plant secondary metabolites are being related to preference and digestibility in specialist and generalist mammalian hindgut herbivores, digestion in ruminants and non-ruminants, and to selected aspects of population dynamics in mammalian herbivores. Results suggest how UV-B-induced changes in plant secondary chemistry affect animal nutrition, and thus animal productivity in a range of mammalian herbivores. Reductions in palatability and digestibility of plant material along with reductions in fecundity and other aspects of population dynamics could have significant economic ramifications for farmers, ranchers and wildlife biologists.

  16. Improved UV-B screening capacity does not prevent negative effects of ambient UV irradiance on PSII performance in High Arctic plants. Results from a six year UV exclusion study

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Ro-Poulsen, H.;

    2010-01-01

    Long-term responses of ambient solar ultraviolet (UV) radiation were investigated on Salix arctica and Vaccinium uliginosum in a High Arctic heath ecosystem in Zackenberg, northeast Greenland. Over a period of six years, UV exclusion was conducted in the growing season by means of filters: 60% UV......, exposing the vegetation to high spring UV-B, and to be present in the future to the degree the ozone layer is not fully recovered....

  17. The effects of altered levels of UV-B radiation on an Antarctic grass and lichen

    NARCIS (Netherlands)

    Lud, D.; Huiskes, A.H.L.; Moerdijk-Poortvliet, T.C.W.; Rozema, J.J.

    2001-01-01

    We report a long-term experiment on the photosynthetic response of natural vegetation of Deschampsia antarctica (Poaceae) and Turgidosculum complicatulum (Lichenes) to altered UV-B levels on Leonie Island, Antarctica. UV-B above the vegetation was reduced by filter screens during two seasons. Half o

  18. On the interaction of UV-B radiation (280-315 mm) with water stress in crop plants

    International Nuclear Information System (INIS)

    Cowpea (Vigna unguiculata L. Walp.) seedlings (3-day-old) were subjected to 4 kinds of experimental treatments: (1) control without exposure to any stress (-D-UV), (2) moderate water stress with no UV-B irradiation (+D-UV), (3) no water stress but exposure to UV-B radiation (-D+UV), and (4) moderate water stress and exposure to UV-B (+D+UV). UV-B and drought stress in the combined form elicited beneficial effects on the morphological and growth characteristics, and a few additive inhibitory effects in some functional processes. An increase in the specific leaf weight (SLW) was observed in the combination of stresses, which could be a defence mechanism against UV-B. The combination of stresses promoted the synthesis of anthocyanins and phenolic compounds. The responses of plants to the combination of stresses indicate that during simultaneous exposure of plants to multiple stresses, one form of stress could minimize the damage by the other. The enhancement of superoxide dismutase (SOD) and catalase activities appear to serve as acclimation mechanisms to scavenge the toxic, free radicals of oxygen produced under stress conditions. However, the inhibition in nitrate metabolism was greater in the combined stresses than in either of the stresses imposed separately. The results of this study illustrate that the interaction of stresses during simultaneous multiple stress conditions brings out certain beneficial effects. (author)

  19. On the interaction of UV-B radiation (280-315 mm) with water stress in crop plants

    Energy Technology Data Exchange (ETDEWEB)

    Balakumar, T.; Vincent, V.H.B. (Univ of Stress Physiology and Plant Biochemistry, Dept. of Botany, The American College, Madurai (India)); Paliwal, K. (Dept. of Plant Sciences, Madurai Kamaraj Univ., Madurai (India))

    1993-01-01

    Cowpea (Vigna unguiculata L. Walp.) seedlings (3-day-old) were subjected to 4 kinds of experimental treatments: (1) control without exposure to any stress (-D-UV), (2) moderate water stress with no UV-B irradiation (+D-UV), (3) no water stress but exposure to UV-B radiation (-D+UV), and (4) moderate water stress and exposure to UV-B (+D+UV). UV-B and drought stress in the combined form elicited beneficial effects on the morphological and growth characteristics, and a few additive inhibitory effects in some functional processes. An increase in the specific leaf weight (SLW) was observed in the combination of stresses, which could be a defence mechanism against UV-B. The combination of stresses promoted the synthesis of anthocyanins and phenolic compounds. The responses of plants to the combination of stresses indicate that during simultaneous exposure of plants to multiple stresses, one form of stress could minimize the damage by the other. The enhancement of superoxide dismutase (SOD) and catalase activities appear to serve as acclimation mechanisms to scavenge the toxic, free radicals of oxygen produced under stress conditions. However, the inhibition in nitrate metabolism was greater in the combined stresses than in either of the stresses imposed separately. The results of this study illustrate that the interaction of stresses during simultaneous multiple stress conditions brings out certain beneficial effects. (au).

  20. Multilevel UV-B Attenuance : Morphological and Chemical Adaptations of Vicia faba to Ultraviolet-B Radiation

    NARCIS (Netherlands)

    Meijkamp, B.B.

    2006-01-01

    Due to anthropogenic reduction of stratospheric ozone, levels of potentially harmful solar UV-B radiation (280-315 nm) have been increasing on earth during the last three decades. The main aim of this thesis was to study growth responses and morphological and chemical adaptation mechanisms to harmf

  1. Photochemical degradation of chromophoric-dissolved organic matter exposed to simulated UV-B and natural solar radiation

    NARCIS (Netherlands)

    Zhang, Y.; Liu, M.; Qin, B.; Feng, S.

    2009-01-01

    Photochemical degradation of chromophoric-dissolved organic matter (CDOM) by UV-B radiation decreases CDOM absorption in the UV region and fluorescence intensity, and alters CDOM composition. CDOM absorption, fluorescence, and the spectral slope indicating the CDOM composition were studied using 0.2

  2. Induction and differential expression of certain novel proteins in Anabaena L31 under UV-B radiation stress

    Directory of Open Access Journals (Sweden)

    Piyoosh Kumar Babele

    2015-02-01

    Full Text Available For examining how UV-B radiation alters the proteome of the N2-fixing cyanobacterium, Anabaena L31, we extracted proteins from cultures irradiated with UV-B + white light and controls (white light irradiated and analyzed the proteins using two-dimensional gel electrophoresis (2-DE and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS. Twenty one proteins, including 2 hypothetical proteins were identified and placed in 8 functional categories. However several of the proteins were housekeeping proteins involved in key metabolic processes such as carbon, amino acid biosynthesis and energy metabolism, certain proteins seem to have a role in stress (antioxidative enzymes, translation, cellular processes and reductases. Two novel hypothetical proteins (all3797 and all4050 were characterized in detail. These two were over-expressed after UV-B irradiation and characterized as FAS 1 (all3797 and PRC barrel-like (all4050 proteins. Bioinformatics analysis revealed that the genes of both the hypothetical proteins have promoter regions as well as transcription binding sites in their upstream region (UTR. Promoters present in all3797 genes suggest their crucial role against UV-B and certain other abiotic stresses. To our knowledge these novel proteins have not been previously reported in any Anabaena strains subjected to UV-B stress. Although we have focused our study on a limited number of proteins, results obtained shed light on the highly complicated but poorly studied aspect of UV-B radiation-mediated changes in the proteome and expression of proteins in cyanobacteria.

  3. The response of human skin commensal bacteria as a reflection of UV radiation: UV-B decreases porphyrin production.

    Directory of Open Access Journals (Sweden)

    Yanhan Wang

    Full Text Available Recent global radiation fears reflect the urgent need for a new modality that can simply determine if people are in a radiation risk of developing cancer and other illnesses. Ultraviolet (UV radiation has been thought to be the major risk factor for most skin cancers. Although various biomarkers derived from the responses of human cells have been revealed, detection of these biomarkers is cumbersome, probably requires taking live human tissues, and varies significantly depending on human immune status. Here we hypothesize that the reaction of Propionibacterium acnes (P. acnes, a human resident skin commensal, to UV radiation can serve as early surrogate markers for radiation risk because the bacteria are immediately responsive to radiation. In addition, the bacteria can be readily accessible and exposed to the same field of radiation as human body. To test our hypothesis, P. acnes was exposed to UV-B radiation. The production of porphyrins in P. acnes was significantly reduced with increasing doses of UV-B. The porphyrin reduction can be detected in both P. acnes and human skin bacterial isolates. Exposure of UV-B to P. acnes- inoculated mice led to a significant decrease in porphyrin production in a single colony of P. acnes and simultaneously induced the formation of cyclobutane pyrimidine dimers (CPD in the epidermal layers of mouse skin. Mass spectrometric analysis via a linear trap quadrupole (LTQ-Orbitrap XL showed that five peptides including an internal peptide (THLPTGIVVSCQNER of a peptide chain release factor 2 (RF2 were oxidized by UV-B. Seven peptides including three internal peptides of 60 kDa chaperonin 1 were de-oxidized by UV-B. When compared to UV-B, gamma radiation also decreased the porphyrin production of P. acnes in a dose-dependent manner, but induced a different signature of protein oxidation/de-oxidation. We highlight that uncovering response of skin microbiome to radiation will facilitate the development of pre

  4. Cadmium telluride quantum dots (CdTe-QDs and enhanced ultraviolet-B (UV-B radiation trigger antioxidant enzyme metabolism and programmed cell death in wheat seedlings.

    Directory of Open Access Journals (Sweden)

    Huize Chen

    Full Text Available Nanoparticles (NPs are becoming increasingly widespread in the environment. Free cadmium ions released from commonly used NPs under ultraviolet-B (UV-B radiation are potentially toxic to living organisms. With increasing levels of UV-B radiation at the Earth's surface due to the depletion of the ozone layer, the potential additive effect of NPs and UV-B radiation on plants is of concern. In this study, we investigated the synergistic effect of CdTe quantum dots (CdTe-QDs, a common form of NP, and UV-B radiation on wheat seedlings. Graded doses of CdTe-QDs and UV-B radiation were tested, either alone or in combination, based on physical characteristics of 5-day-old seedlings. Treatments of wheat seedlings with either CdTe-QDs (200 mg/L or UV-B radiation (10 KJ/m(2/d induced the activation of wheat antioxidant enzymes. CdTe-QDs accumulation in plant root cells resulted in programmed cell death as detected by DNA laddering. CdTe-QDs and UV-B radiation inhibited root and shoot growth, respectively. Additive inhibitory effects were observed in the combined treatment group. This research described the effects of UV-B and CdTe-QDs on plant growth. Furthermore, the finding that CdTe-QDs accumulate during the life cycle of plants highlights the need for sustained assessments of these interactions.

  5. Exposure of Metarhizium acridum mycelium to light induces tolerance to UV-B radiation.

    Science.gov (United States)

    Brancini, Guilherme T P; Rangel, Drauzio E N; Braga, Gilberto Ú L

    2016-03-01

    Metarhizium acridum is an entomopathogenic fungus commonly used as a bioinsecticide. The conidium is the fungal stage normally employed as field inoculum in biological control programs and must survive under field conditions such as high ultraviolet-B (UV-B) exposure. Light, which is an important stimulus for many fungi, has been shown to induce the production of M. robertsii conidia with increased stress tolerance. Here we show that a two-hour exposure to white or blue/UV-A light of fast-growing mycelium induces tolerance to subsequent UV-B irradiation. Red light, however, does not have the same effect. In addition, we established that this induction can take place with as little as 1 min of white-light exposure. This brief illumination scheme could be relevant in future studies of M. acridum photobiology and for the production of UV-B resistant mycelium used in mycelium-based formulations for biological control. PMID:26884481

  6. Influence of UV-B radiation on lead speciation in the presence of natural particles of estuarine waters.

    Science.gov (United States)

    Kumar, M Praveen; Mota, A M; Gonçalves, M L S

    2016-09-01

    The influence of UV-B irradiation on filtered and non-filtered water samples collected in a non-polluted area of Tagus estuary was evaluated in this study. In the laboratory, both samples were titrated with lead (Pb(+2)) followed by differential pulse anodic stripping voltammetry (DPASV), before and after 1 and 10 days under UV-B irradiation. Metal-ligand complexing parameters were obtained based on a macromolecular heterogeneous ligand described by two distinct sites with a labile behavior, and a third small homogeneous weaker group, which concentration was determined from a potentiometric titration. Under UV-B radiation, the complexing strength decreased with time in both (filtered and non-filtered) irradiated samples, but this effect was more pronounced in the non-filtered water, which might be due to some adsorption of dissolved macromolecular ligands on the particles and/or to further degradation of dissolved organic matter (DOM). Furthermore, the presence of particles favored the break-down of the macromolecular ligand under long UV-B exposure time. These results present ecological implications for the estuarine ecosystems such as bioavailability and toxicity. PMID:27230154

  7. Impact of UV-B radiation on photosynthetic assimilation of 14C-bicarbonate and inorganic 15N-compounds by cyanobacteria

    International Nuclear Information System (INIS)

    The cyanobacteria Anabaena cylindrica and Synechococcus leopoliensis (=Anacystis nidulans) were grown at different levels of UV-B radiation (439, 717, 1230 and 1405 J m-2d-1, weighted according Caldwell, 1971) for 2 days. Dry weight was hardly affected but phycocyanin content of both species decreased linearly to the level of UV-B radiation. Contents of protein, carotenoids and chlorophyll a were reduced only after exposure to high doses (1230 J m-2d-1) of UV-B radiation. Photosynthetic 14CO2 fixation of Anabaena cells was reduced linearly with increasing UV-B dose whereas no effect could be observed in Synechococcus. A depression of photosynthetic 15N-nitrate uptake was found after UV-B stress in both species. UV-B irradiance caused an increase of 15N-incorporation into glutamine, but no effect was noted for incorporation into alanine or aspartic acid. An increase of 15N-excess in glutamic acid linear with the UV-B dose was observed in Synechococcus, only. Patterns of 14C-labelled photosynthetic products were either less affected by UV-B radiation (Anabaena) or an enhancement of 14C-label in total amino acids was detected (Synechococcus). The amount of total free amino acids increased parallel to the level of UV-B radiation. Only, the high dose of UV-B (1405 J m-2 d-1, weighted) results in a decrease of the glutamine pool. Our results indicate an inhibition of glutamate synthase by UV-B irradiation in Anabaena, only. Results were discussed with reference to the damage of the photosynthetic apparatus. (orig.)

  8. Effects of UV-B radiation on microcystin production of a toxic strain of Microcystis aeruginosa and its competitiveness against a non-toxic strain

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhen, E-mail: zhyang@niglas.ac.cn; Kong, Fanxiang, E-mail: fxkong@niglas.ac.cn; Shi, Xiaoli; Yu, Yang; Zhang, Min

    2015-02-11

    Highlights: • UV-B radiation showed higher inhibition to non-toxin producing than toxin-producing strains on growth and photosynthetic activity. • Both intracellular and extracellular MC contents decreased markedly under UV-B radiation. • Higher resistance to UV-B radiation helped toxin-producing M. aeruginosa to predominate in the competition. - Abstract: Microcystins (MCs) produced by toxic cyanobacteria pose a health hazard to humans and animals. Some environmental factors can alter the MC concentrations by affecting the abundance of toxin-producing strains in a cyanobacteria population and/or their toxin production. In this study, we designed a monoculture and competition experiment to investigate the impacts of UV-B radiation on MC production and the competition between toxin and non-toxin producing strains of Microcystis aeruginosa. UV-B radiation resulted in higher inhibition of the growth and photosynthetic activity of the non-toxin producing strain relative to that observed for the toxin-producing strain. Both intracellular and extracellular MC contents decreased markedly when the toxin-producing strain was exposed to UV-B radiation. In addition, a quantitative real-time PCR assay revealed that the ratio of toxin-producing M. aeruginosa under UV-B exposure was higher than that under PAR alone at an early stage of the experiment. However, its abundance under UV-B exposure was lower compared with the PAR alone treatment after day 12. Our study demonstrated that UV-B radiation has a great impact on the abundance of the toxin-producing strain in the Microcystis population and their toxin production, which suggests that the fluctuation of UV-B radiation affects the MC level of cyanobacteria blooms.

  9. Effects of UV-B radiation on microcystin production of a toxic strain of Microcystis aeruginosa and its competitiveness against a non-toxic strain

    International Nuclear Information System (INIS)

    Highlights: • UV-B radiation showed higher inhibition to non-toxin producing than toxin-producing strains on growth and photosynthetic activity. • Both intracellular and extracellular MC contents decreased markedly under UV-B radiation. • Higher resistance to UV-B radiation helped toxin-producing M. aeruginosa to predominate in the competition. - Abstract: Microcystins (MCs) produced by toxic cyanobacteria pose a health hazard to humans and animals. Some environmental factors can alter the MC concentrations by affecting the abundance of toxin-producing strains in a cyanobacteria population and/or their toxin production. In this study, we designed a monoculture and competition experiment to investigate the impacts of UV-B radiation on MC production and the competition between toxin and non-toxin producing strains of Microcystis aeruginosa. UV-B radiation resulted in higher inhibition of the growth and photosynthetic activity of the non-toxin producing strain relative to that observed for the toxin-producing strain. Both intracellular and extracellular MC contents decreased markedly when the toxin-producing strain was exposed to UV-B radiation. In addition, a quantitative real-time PCR assay revealed that the ratio of toxin-producing M. aeruginosa under UV-B exposure was higher than that under PAR alone at an early stage of the experiment. However, its abundance under UV-B exposure was lower compared with the PAR alone treatment after day 12. Our study demonstrated that UV-B radiation has a great impact on the abundance of the toxin-producing strain in the Microcystis population and their toxin production, which suggests that the fluctuation of UV-B radiation affects the MC level of cyanobacteria blooms

  10. The effect of UV-B radiation enhancement on the interspecific competition between Skeletonema costatum and Heterosigma akashiwo

    Institute of Scientific and Technical Information of China (English)

    XIAO Hui; TANG Xuexi; ZHANG Peiyu; CAI Hengjiang

    2005-01-01

    The responses of the interspecific competition between Skeletonema costatum and Heterosigma akashiwo to UV-B radiation enhancement were studied by the co-culture method. The results showed that Heterosigma akashiwo exhibited inhibition on the growth of Skeletonema costatum, and with the increase of initial inoculation density of Heterosigma akashiwo, heavier inhibition on Skeletonema costatum appeared. Under different inoculation proportions, Heterosigma akashiwo could always be in predominance in competition with Skeletonema costatum. The UV-B radiation treatment could change the competition relationship between Skeletonema costatum and Heterosigma akashiwo, which could increase the competitive dominance of Skeletonema costatum and decrease the competitive dominance of Heterosigma akashiwo. When the inoculation proportions of Heterosigma akashiwo and Skeletonema costatum were H:S=1:4 and H:S=1:1, Skeletonema costatum was in predominance in this competition; however, Heterosigma akashiwo was in predominance when the inoculation proportion was H:S=4:1.

  11. Epidermal transmittance and phenolic composition in leaves of atrazine-tolerant and atrazine-sensitive cultivars of Brassica napus grown under enhanced UV-B radiation

    International Nuclear Information System (INIS)

    Experiments were conducted on the atrazine-tolerant mutant Stallion and the atrazine-sensitive cv. Paroll of Brassica napus L., which were grown under either visible light or with the addition of UV-B radiation (280–320 nm) for 15 days. The mutant has been shown to be sensitive to high levels of visible light as compared to the atrazine-sensitive cultivar and therefore we wished to determine plant response to UV-B radiation with respect to potential pigment changes, certain anatomical features, radiation penetration and partial photosynthesis. With regard to pigment changes, we were particularly interested in whether the compositional shift in flavonol pigments under enhanced UV-B radiation, previously suggested to favour increased antioxidant activity, is confined to the adaxial epidermis, which generally receives most UV-B radiation or whether the pigment shift is also inducible in the abaxial epidermis.As was to be expected, the penetration of UV-B radiation (310 nm) was lower in the UV-B-exposed plants, which was correlated with an increased amount of UV-screening pigments in the adaxial and abaxial epidermal layers. The main flavonoid glycosides showed the largest shift from kaempferol to quercetin as aglycone moiety in the adaxial epidermal layer. However, in the abaxial epidermal layer the hydroxycinnamic acid (HCA) derivatives and kaempferol glycosides were predominant. Penetration of 430 nm light was higher after UV-B exposure, and probably contributed to the fact that photosynthetic efficiency of photosystem II was unchanged or higher after UV-B exposure. UV-B radiation decreased leaf area in the atrazine-tolerant mutant only. Both cultivars showed an increased leaf thickness after UV-B exposure due to cell elongation mainly of the palisade tissue. This was especially evident in the mutant

  12. The Effect of UV-B Radiation on Bufo arenarum Embryos Survival and Superoxide Dismutase Activity

    Directory of Open Access Journals (Sweden)

    O. Fridman

    2006-03-01

    Full Text Available The exposure of Bufo arenarum embryos to 300-310 nm UV-B at a dose of 4,104 Joule/m2 resulted in 100% lethality within 24 hr while 820 Joule/m2 was the NOEC value for short-term chronic (10 days exposure. The dose response curves show that lethal effects are proportional with the dose and achieve its highest value within 48 hr post exposure. The superoxide dismutase (SOD activity in amphibian embryos for sublethal UV-B exposures was evaluated by means of UV-B treatments with 273 (A, 820(B, 1368(C and 1915(D Joule/m2 at 2 and 5 hours post irradiation. The SOD activity in units/mg protein in A, B, C and D at 2 hr after treatments were 80.72 ± 14.29, 74.5 ± 13.19, 39.5 ± 6.99 and 10.7 ± 1.89 respectively while for control embryos it was 10.88 ± 1.31. At 5 hr after treatments the SOD values were similar to those found in control embryos. The results confirm the high susceptibility of amphibian embryos to UV-B and point out that the SOD activity is enhanced by low doses of UV-B irradiation achieving significantly higher values than in control embryos at 2 hr post exposure.

  13. Time sequence of the damage to the acceptor and donor sides of photosystem II by UV-B radiation as evaluated by chlorophyll a fluorescence

    NARCIS (Netherlands)

    Rensen, van J.J.S.; Vredenberg, W.J.; Rodrigues, G.C.

    2007-01-01

    The effects of ultraviolet-B (UV-B) radiation on photosystem II (PS II) were studied in leaves of Chenopodium album. After the treatment with UV-B the damage was estimated using chlorophyll a fluorescence techniques. Measurements of modulated fluorescence using a pulse amplitude modulated fluoromete

  14. Lipids and pigment-protein complexes of photosynthetic apparatus of Deschampsia antarctica Desv. plants under UV-B radiation

    Directory of Open Access Journals (Sweden)

    Svietlova N. B.

    2012-01-01

    Full Text Available Aim. To investigate structural and functional modifications of major components of photosynthetic membranes of endemic antarctic species D. antarctica under UV-B radiation. Methods. For quantitative determination of photosynthetic membrane components we used Arnon’s method (for chlorophylls and carotenoids; separation of carotenoids was carried out by Merzlyak’s method; polar lipids were isolated by Zill and Harmon method in modification of Yakovenko and Mihno; glycolipids separation and identification we carried out by Yamamoto method; and sulfoquinovosyl diacylglycerol content was determined by Kean method. The separation, disintegration and determination of pigment-protein complexes of chloroplasts were carried out by Anderson method. Authenticity of differences between the mean arithmetic values of indices was set after the Student criterion. Differences were considered as reliable at p 0.05. Results. We determined structural and functional changes in lipids, carotenoids and pigment-protein complexes at the photosyntetic apparatus level in D. antarctica plants under UV-B radiation. Conclusions. Adaptation of D. antarctica plants to UV-B radiation is accompanied by a cascade of physiological and biochemical rearrangements at the level of photosynthetic apparatus, manifested as the changes in pigment, lipid and pigment-protein complexes content

  15. Antioxidant responses of damiana (Turnera diffusa Willd to exposure to artificial ultraviolet (UV radiation in an in vitro model: part II; UV-B radiation

    Directory of Open Access Journals (Sweden)

    Lluvia de Abril Alexandra Soriano-Melgar

    2014-05-01

    Full Text Available Introduction: Ultraviolet type B (UV-B radiation effects on medicinal plants have been recently investigated in the context of climate change, but the modifications generated by UV-B radiation might be used to increase the content of antioxidants, including phenolic compounds. Objective: To generate information on the effect of exposure to artificial UV-B radiation at different high-doses in the antioxidant content of damiana plants in an in vitro model. Methods: Damiana plantlets (tissue cultures in Murashige-Skoog medium were irradiated with artificial UV-B at 3 different doses (1 0.5 ± 0.1 mW cm-2 (high for 2 h daily, (2 1 ± 0,1 mW cm-2 (severe for 2 h daily, or (3 1 ± 0.1 mW cm-2 for 4 h daily during 3 weeks. The concentration of photosynthetic pigments (chlorophylls a and b, carotenoids, vitamins (C and E and total phenolic compounds, the enzymatic activity of superoxide dismutase (SOD, EC 1.15.1.1 and total peroxidases (POX, EC 1.11.1, as well as total antioxidant capacity and lipid peroxidation levels were quantified to assess the effect of high artificial UV-B radiation in the antioxidant content of in vitro damiana plants. Results: Severe and high doses of artificial UV-B radiation modified the antioxidant content by increasing the content of vitamin C and decreased the phenolic compound content, as well as modified the oxidative damage of damiana plants in an in vitro model. Conclusion: UV-B radiation modified the antioxidant content in damiana plants in an in vitro model, depending on the intensity and duration of the exposure.

  16. Anthropogenic changes in the surface all-sky UV-B radiation through 1850–2005 simulated by an Earth system model

    Directory of Open Access Journals (Sweden)

    T. Yokohata

    2012-02-01

    Full Text Available The historical anthropogenic change in the surface all-sky UV-B (solar ultraviolet: 280–315 nm radiation through 1850–2005 is evaluated using an Earth system model. Responses of UV-B dose to anthropogenic changes in ozone and aerosols are separately evaluated using a series of historical simulations including/excluding these changes. Increases in these air pollutants cause reductions in UV-B transmittance, which occur gradually/rapidly before/after 1950 in and downwind of industrial and deforestation regions. Furthermore, changes in ozone transport in the lower stratosphere, which is induced by increasing greenhouse gas concentrations, increase ozone concentration in the extratropical upper troposphere and lower stratosphere. These transient changes work to decrease the amount of UV-B reaching the Earth's surface, counteracting the well-known effect increasing UV-B due to stratospheric ozone depletion, which developed rapidly after ca. 1980. As a consequence, the surface all-sky UV-B radiation change between 1850 and 2000 is negative in the tropics and NH extratropics and positive in the SH extratropics. Comparing the contributions of ozone and aerosol changes to the UV-B change, the transient change in ozone absorption of UV-B mainly determines the total change in the surface all-sky UV-B radiation at most locations. On the other hand, the aerosol direct and indirect effects on UV-B play an equally important role to that of ozone in the NH mid-latitudes and tropics. A typical example is East Asia (25° N–60° N and 120° E–150° E, where the effect of aerosols (ca. 70% dominates the total UV-B change.

  17. Anthropogenic changes in the surface all-sky UV-B radiation through 1850–2005 simulated by an Earth system model

    Directory of Open Access Journals (Sweden)

    S. Watanabe

    2012-06-01

    Full Text Available The historical anthropogenic change in the surface all-sky UV-B (solar ultraviolet: 280–315 nm radiation through 1850–2005 is evaluated using an Earth system model. Responses of UV-B dose to anthropogenic changes in ozone and aerosols are separately evaluated using a series of historical simulations including/excluding these changes. Increases in these air pollutants cause reductions in UV-B transmittance, which occur gradually/rapidly before/after 1950 in and downwind of industrial and deforestation regions. Furthermore, changes in ozone transport in the lower stratosphere, which is induced by increasing greenhouse gas concentrations, increase ozone concentration in the extratropical upper troposphere and lower stratosphere. These transient changes work to decrease the amount of UV-B reaching the Earth's surface, counteracting the well-known effect increasing UV-B due to stratospheric ozone depletion, which developed rapidly after ca. 1980. As a consequence, the surface UV-B radiation change between 1850 and 2000 is negative in the tropics and NH extratropics and positive in the SH extratropics. Comparing the contributions of ozone and aerosol changes to the UV-B change, the transient change in ozone absorption of UV-B mainly determines the total change in the surface UV-B radiation at most locations. On the other hand, the aerosol direct and indirect effects on UV-B play an equally important role to that of ozone in the NH mid-latitudes and tropics. A typical example is East Asia (25° N–60° N and 120° E–150° E, where the effect of aerosols (ca. 70% dominates the total UV-B change.

  18. The combined effects of CO2 concentration and enhanced UV-B radiation on faba bean. 3. Leaf optical properties, pigments, stomatal index and epidermal cell density

    International Nuclear Information System (INIS)

    Seedlings of Vicia faba L. (cv. Minica) were grown in a factorial experiment in a greenhouse. The purpose of the study was to determine whether CO2 enrichment and supplemental UV-B radiation affect leaf optical properties and whether the combined effects differ from single factor effects. Seedlings were grown at either 380 μmol mol-1 or 750 μmol mol-1 CO2 and at four levels of UV-B radiation. After 20 and 40 days of treatment, absorptance, transmittance and reflectance of photosynthetically active radiation (PAR) were measured on the youngest fully developed leaf. On the same leaf, the specific leaf area on a fresh weight basis (SLAfw), chlorophyll content, UV-B absorbance, transmittance of UV light and stomatal index were measured. UV-B radiation significantly increased PAR absorptance and decreased PAR transmittance. The increased PAR absorptance can be explained by an increased chlorophyll content in response to UV-B radiation. Leaf transmittance of UV radiation decreased with increasing UV-B levels mainly caused by increased absorbance of UV absorbing compounds. UV-B radiation decreased both the stomatal density and epidermal cell density of the abaxial leaf surface, leaving the stomatal index unchanged. Effects of CO2 enrichment were less pronounced than those of UV-B radiation. The most important CO2 effect was an increase in stomatal density and epidermal cell density of the adaxial leaf surface. The stomatal index was not affected. No interaction between CO2 and UV-B radiation was found. The results are discussed in relation to the internal light environment of the leaf. (author)

  19. Photosynthetic 14CO2 fixation and [15N]-ammonia assimilation during UV-B radiation of Lithodesmium variabile

    International Nuclear Information System (INIS)

    Uptake of [15N]-ammonia was more sensitive to UV-B exposure than the total 14CO2 fixation rate of Lithodesmium variabile Takano. Short-term UV-B radiation (15 min) had practically no effect on the kinetics of [15N]-ammonia, whereas there was an effect on [14C]-bicarbonate uptake rate. A significant reduction was found after 30 and 60 min UV-B stress. The time course of photosynthetic uptake of 15NH4Cl at several wavelengths was markedly depressed at shorter wavelengths (irradiation with WG 280). A short-term (11 min) exposure to ultraviolet radiation had no influence on the [14C]-labeled photosynthetic products. However, the [15N]-label of several amino acids and the ratio of [15N]-glutamine to [15N]-glutamic acid varied after irradiation with different ultraviolet wavebands. The results are discussed with reference to UV damage to the key enzymes of nitrogen metabolism. (author)

  20. Effects of UV-B radiation on photosynthesis and transpiration in leaves and pods of two yellow lupine varieties

    International Nuclear Information System (INIS)

    Changes in the rates of photosynthesis and transpiration, and the greenness index (SPAD) were studied in a pot experiment performed on leaves of two morphological types of yellow lupine, under conditions of differentiated UV-B radiation. The rates of photosynthesis and transpiration, stomatal conductance, and concentration of intercellular CO2 were also measured in pods of two yellow lupine varieties tested in the study. It was found that the intensity of UV-B irradiation, in a range from 1.8 to 4.5 W/square m, administered over the entire vegetation season, did not reduce the level of leaf photosynthesis in the two yellow lupine varieties. It was also reported that photosynthesis rate in yellow lupine pods, measured as a level of CO2 assimilation, assumed negative values, which indicates that the amount of gas liberated to the atmosphere was higher than its uptake

  1. Effects of UV-B radiation on microcystin production of a toxic strain of Microcystis aeruginosa and its competitiveness against a non-toxic strain.

    Science.gov (United States)

    Yang, Zhen; Kong, Fanxiang; Shi, Xiaoli; Yu, Yang; Zhang, Min

    2015-01-01

    Microcystins (MCs) produced by toxic cyanobacteria pose a health hazard to humans and animals. Some environmental factors can alter the MC concentrations by affecting the abundance of toxin-producing strains in a cyanobacteria population and/or their toxin production. In this study, we designed a monoculture and competition experiment to investigate the impacts of UV-B radiation on MC production and the competition between toxin and non-toxin producing strains of Microcystis aeruginosa. UV-B radiation resulted in higher inhibition of the growth and photosynthetic activity of the non-toxin producing strain relative to that observed for the toxin-producing strain. Both intracellular and extracellular MC contents decreased markedly when the toxin-producing strain was exposed to UV-B radiation. In addition, a quantitative real-time PCR assay revealed that the ratio of toxin-producing M. aeruginosa under UV-B exposure was higher than that under PAR alone at an early stage of the experiment. However, its abundance under UV-B exposure was lower compared with the PAR alone treatment after day 12. Our study demonstrated that UV-B radiation has a great impact on the abundance of the toxin-producing strain in the Microcystis population and their toxin production, which suggests that the fluctuation of UV-B radiation affects the MC level of cyanobacteria blooms.

  2. Effects of UV-B radiation on anatomical characteristics, phenolic compounds and gene expression of the phenylpropanoid pathway in highbush blueberry leaves.

    Science.gov (United States)

    Inostroza-Blancheteau, Claudio; Reyes-Díaz, Marjorie; Arellano, Alejandro; Latsague, Mirtha; Acevedo, Patricio; Loyola, Rodrigo; Arce-Johnson, Patricio; Alberdi, Miren

    2014-12-01

    The effects of increased doses of UV-B radiation on anatomical, biochemical and molecular features of leaves of two highbush blueberry (Vaccinium corymbosum L. cv. Brigitta and Bluegold) genotypes were investigated. Plants were grown in a solid substrate and exposed to 0, 0.07, 0.12 and 0.19 Wm(-2) of biologically effective UV-B radiation for up to 72 h. Leaf thickness and the adaxial epidermis thickness fell more than 3-fold in both genotypes at the highest UV-B dose. Moreover, in Bluegold an evident disorganization in the different cell layers was observed at the highest UV-B radiation. A significant decrease in chlorophyll a/b after 6 h in Brigitta under the greater UV-B doses was observed. Anthocyanin and total phenolics were increased, especially at 0.19 Wm(-2), when compared to the control in both genotypes.Chlorogenic acid was the most abundant hydroxycinnamic acid in Brigitta, and was significantly higher (P ≤ 0.05) than in Bluegold leaves. Regarding the expression of phenylpropanoid genes, only the transcription factor VcMYBPA1 showed a significant and sustained induction at higher doses of UV-B radiation in both genotypes compared to the controls. Thus, the reduction of leaf thickness concomitant with a lower lipid peroxidation and rapid enhancement of secondary metabolites, accompanied by a stable induction of the VcMYBPA1 transcription factor suggest a better performance against UV-B radiation of the Brigitta genotype.

  3. Study of the effect of different type of aerosols on UV-B radiation from measurements during EARLINET

    Directory of Open Access Journals (Sweden)

    D. S. Balis

    2004-01-01

    Full Text Available Routine lidar measurements of the vertical distribution of the aerosol extinction coefficient and the extinction-to-backscatter ratio have been performed at Thessaloniki, Greece using a Raman lidar system in the frame of the EARLINET project since 2000. Co-located spectral and broadband solar UV-B irradiance measurements, as well as total ozone observations, were available whenever lidar measurements were obtained. From the available measurements several cases could be identified that allowed the study of the effect of different types of aerosol on the levels of the UV-B solar irradiance at the Earth's surface. The TUV radiative transfer model has been used to simulate the irradiance measurements, using total ozone and the lidar aerosol data as input. From the comparison of the model results with the measured spectra the effective single scattering albedo was determined using an iterative procedure, which has been verified against results from the 1998 Lindenberg Aerosol Characterization Experiment. It is shown that for the same aerosol optical depth and for the same total ozone values the UV-B irradiances at the Earth's surface can show differences up to 10%, which can be attributed to differences in the aerosol type. It is shown that the combined use of the estimated single scattering albedo and of the measured extinction-to-backscatter ratio leads to a better characterization of the aerosol type probed.

  4. Study of the effect of different type of aerosols on UV-B radiation from measurements during EARLINET

    Directory of Open Access Journals (Sweden)

    D. S. Balis

    2003-09-01

    Full Text Available Routine lidar measurements of the vertical distribution of the aerosol extinction coefficient and the extinction-to-backscatter ratio have been performed at Thessaloniki, Greece using a Raman lidar system in the frame of the EARLINET project since 2000. Spectral and broadband UV-B irradiance measurements, as well as total ozone observations, were available whenever lidar measurements were obtained. From the available measurements several cases could be identified that allowed the study of the effect of different types of aerosol on the levels of the UV-B solar irradiance at the Earth's surface. The TUV radiative transfer model has been used to simulate the irradiance measurements, using total ozone and the lidar aerosol data as input. From the comparison of the model results with the measured spectra the effective single scattering albedo was determined using an iterative procedure, which has been verified against results from the 1998 Lindenberg Aerosol Characterization Experiment. It is shown that the same aerosol optical depth and same total ozone values can show differences up to 10% in the UV-B irradiance at the Earth's surface, which can be attributed to differences in the aerosol type. It is shown that the combined use of the estimated single scattering albedo and the measured extinction-to-backscatter ratio leads to a better characterization of the aerosol type probed.

  5. Competition and sensitivity of wheat and wild oat exposed to enhanced UV-B radiation at different densities under field conditions

    International Nuclear Information System (INIS)

    The influence of enhanced UV-B radiation (approximating a 15% ozone layer reduction) on competitive interaction between spring wheat (Triticum aestivum) and wild oat (Avena fatua) was examined in the field. The density-dependent mortality of both wheat and wild oat did not exhibit a significant difference between control and UV-B treatment conditions. A relatively high degree of competitive stress enhanced the effects of UV-B stress on biomass reduction. The relative competitive status of wheat in terms of total biomass increased under UV-B enhancement while it decreased when based upon grain production. Shifts in competitive balance occurred with significant changes in total biomass, especially when plants grew at higher densities in monocultures and mixtures. The sensitivity of wild oat to intensification of UV-B radiation at higher densities in mixtures was greater than that at lower densities. At all densities examined, wheat grown in mixture was significantly less sensitive to UV-B radiation than that in monoculture, and just the opposite for wild oat. The density of monocultures did not alter the response index (RI) of wheat and wild oat to enhanced UV-B radiation. (author)

  6. Combined effects of elevated UV-B radiation and the addition of selenium on common (Fagopyrum esculentum Moench) and tartary [Fagopyrum tataricum (L.) Gaertn.] buckwheat

    International Nuclear Information System (INIS)

    Plants of Fagopyrum esculentum and Fagopyrum tataricum grown outdoors under three levels of UV-B radiation were studied for 9 weeks, from sowing to ripening. At week 7 they were sprayed with Se solution (1 g/cubic m). Morphological, physiological, and biochemical parameters of the plants were monitored. Elevated UV-B radiation, corresponding to a 17% reduction of the ozone layer, induced synthesis of UV absorbing compounds. In both species it caused a reduction in amounts of chlorophyll a during the time of intensive growth. This effect was increased in tartary buckwheat in the presence of Se. The respiratory potential was lower in plants subjected to enhanced UV-B radiation during the time of intensive growth. The effective quantum yield of photosystem 2 was also reduced in both species and was mitigated by the addition of Se. Se also mitigated the stunting effect of UV-B radiation and the lowering of biomass in common buckwheat

  7. UV-B Radiation Suppresses the Growth and Antioxidant Systems of Two Marine Microalgae, Platymonas subcordiformis (Wille) Hazen and Nitzschia closterium (Ehrenb.) W. Sm

    Institute of Scientific and Technical Information of China (English)

    Pei-Yu ZHANG; Juan YU; Xue-Xi TANG

    2005-01-01

    This study investigated whether increased solar UV-B radiation (280-315 nm) could suppress the growth of marine microalgae through effects on their antioxidant systems. Two marine microalgae species, Platymonas subcordiformis (Wille) Hazen and Nitzschia closterium (Ehrenb.) W. Sm, were exposed to a range of UV-B radiation and both showed reductions in their growth rates, and the chlorophyll a (Chl a) and carotenoid (Car) contents when UV-B radiation dose increased. Superoxide anion radical (O2)production and the concentration of hydrogen peroxide (H2O2) and malodiadehyde (MDA) also increased with the increasing of UV-B radiation. Antioxidant systems, non-enzymic components (Car and glutathione content) and enzymic components (superoxide dismutase (SOD) and catalase (CAT) activity), decreased as a result of enhanced UV-B radiation. When the exogenous glutathione (GSH) was added, the effects of UVB radiation on the growth of the two species were alleviated. These results suggest that enhanced UV-B radiation suppressed the antioxidant systems and caused some active oxygen species to accumulate, which in turns retarded the development of the marine microalgae.

  8. Changes of proteins in the Antarctic ice microalga Chlamydomonas sp. cultured under UV-B radiation stress

    Institute of Scientific and Technical Information of China (English)

    KAN Guangfeng; MIAO Jinlai; SHI Cuijuan; LI Guangyou

    2006-01-01

    Antarctic ice microalga Chlamydomonas sp. can thrive undisturbed under high UV radiation in the Antarctic ice layer. However, it is unknown that the initial adaptation mechanisms in protein level occurring in response to high UV radiation. Global-expression profiling of proteins in response to stress was analyzed by two-dimensional electrophoresis (2-DE) and image analysis. In the 2-DE analysis,protein preparation is the key step. Three different protein extract methods were compared, and the results showed that the trichloroacetic acid (TCA)-acetone fractional precipitation method was the fittest one. At the same time, the proteins in Chlamydomonas sp. were compared in 2-DE way, and the synthesis of seven protein spots was found disappeared and 18 decreased after exposed to UV-B radiation. In addition, 14 protein spots were enhanced or induced, among which two new peptides (20 and 21 kDa) appeared whose isoelectric point (pI) was 7.05 and 4.60 respectively. These changed proteins might act as key role in the acclimation of Antarctic ice microalga to UV-B radiation

  9. Responses of photosynthetic properties and chloroplast ultrastructure of two moss crusts from a desert biological soil crust to supplementary UV-B radiation

    Science.gov (United States)

    Hui, Rong; Li, Xinrong; Zhao, Yang; Pan, Yanxia

    2016-04-01

    Our understanding of plant responses to supplementary ultraviolet-B (UV-B) radiation due to stratospheric ozone depletion has improved over recent decades. However, research on biological soil crusts (BSCs) is scarce and it remains controversial. Laboratory studies were conducted to investigate the influence of UV-B radiation on the Bryum argenteum and Didymodon vinealis isolated from BSCs, which are both dominant species in moss crusts found within patches of shrubs and herbs in the Tengger Desert of northern China. The aim of the current work was to evaluate whether supplementary UV-B radiation affected photosynthetic properties and chloroplast ultrastructure of two moss crusts and whether response differences were observed between the crusts. Four levels of UV-B radiation of 2.75 (control), 3.08, 3.25, and 3.41 W m-2 was achieved using fluorescence tube systems for 10 days, simulating 0, 6, 9, and 12% of stratospheric ozone at the latitude of Shapotou, respectively. We measured photosynthetic apparatus as assessed by chlorophyll a fluorescence parameters, photosynthetic pigment contents, and observations of chloroplast ultrastructure. Additionally, soluble proteins and UV-B absorbing compounds were simultaneously investigated. The results of this study showed that chlorophyll a fluorescence parameters (i.e., the maximal quantum yield of PSII photochemistry, the effective quantum yield of PSII photochemistry, and photochemical quenching coefficient), photosynthetic pigment contents, soluble protein contents, total flavonoid contents and the ultrastructure were negatively influenced by elevated UV-B radiation and the degree of detrimental effects significantly increased with the intensity of UV-B radiation. Moreover, results demonstrated that the negative effects on photosynthesis and chloroplast ultrastructure were more serious in B. argenteum than that in D. vinealis. These results may not only provide a potential mechanism for supplemental UV-B effects on

  10. Effects of UV-B radiation on the growth and reproduction of Vicia angustifolia%UV-B辐射对窄叶野豌豆生长繁殖的影响

    Institute of Scientific and Technical Information of China (English)

    王颖; 王兴安; 王仁君; 邱念伟; 马宗琪; 杜国祯

    2012-01-01

    A simulation experiment with supplementation and exclusion of solar ultraviolet-B ( UV-B) radiation was conducted to study the effects of enhanced and near ambient UV-B radiation on the growth and reproduction of alpine annual pasture Vicia angustifolia on Qinghai-Tibet Plateau. Enhanced UV-B decreased the plant height and biomass, biomass allocation to fruit, flower number, and 100-seed mass significantly, delayed flowering stage, increased the concentration degree of flowering and success rate of reproduction, but had little effect on seed yield. Near ambient UV-B radiation made the plant height increased after an initial decrease, decreased biomass allocation to fruit and 100-seed mass, but little affected flowering duration, flower number, and seed yield. Both enhanced and near ambient UV-B radiation could inhibit the growth and production of V. angustifolia, and the effect of enhanced UV-B radiation was even larger.%采用增补和滤除掉部分自然UV-B辐射的模拟试验,研究了增强和近环境UV-B辐射对高寒草甸一年生牧草窄叶野豌豆生长和繁殖的影响.结果表明:增补UV-B辐射处理后,窄叶野豌豆的株高、生物量、分配向果实的生物量、总花数和种子百粒重均显著下降,花期延迟,开花集中度和繁殖成功率有所提高,而种子产量无显著变化.相对于减弱UV-B辐射处理,近环境UV-B辐射使窄叶野豌豆的株高先降后升,分配向果实的生物量减少,花期、花数和种子产量无显著变化,种子百粒重减小.增强和近环境UV-B辐射对窄叶野豌豆的生长和繁殖有一定的抑制作用,且增强UV-B辐射的影响更大.

  11. A comparison of the ecophysiological responses of Chenopodium album and Amaranthus retroflexus to the exclusion of ultraviolet-A and UV-B radiation in the field and the glasshouse

    Energy Technology Data Exchange (ETDEWEB)

    Cann, J.C.; Miller, S.D.; Vogelmann, T.C. [Univ. of Wyoming, Laramie, WY (United States)

    1995-06-01

    The goal of this study was to determine how well two naturalized C{sub 3} and C{sub 4} weedy species, Chenopodium album and Amaranthus retroflexus, would respond to ultraviolet exclusion under field and glasshouse conditions. These plants were grown in: (1) a high elevation (2188m) field plot in Laramie, WY USA, during the summer of 1994 and (2) a glasshouse during the spring of 1995. Three types of plastic were used to exclude either UV-A, UV-B, or both UV-A and UV-B. During the summer of 1994, photosynthetically active radiation and UV-B fluence rates were measured daily. A total of seven biochemical and physiological parameters, such as chlorophyll, flavonoids, biomass, growth rate, stomatal density, and stomatal conductance were measured at bimonthly intervals. The results of the field experiment show almost no effects of excluding UV-A, UV-B, or both upon plant growth, pigment content, or photosynthetic response. Our results suggest that these plants, unlike some crop plants, may be physiologically pre-adapted to tolerate high ambient levels of ultraviolet radiation.

  12. High mortality of Red Sea zooplankton under ambient solar radiation.

    Directory of Open Access Journals (Sweden)

    Ali M Al-Aidaroos

    Full Text Available High solar radiation along with extreme transparency leads to high penetration of solar radiation in the Red Sea, potentially harmful to biota inhabiting the upper water column, including zooplankton. Here we show, based on experimental assessments of solar radiation dose-mortality curves on eight common taxa, the mortality of zooplankton in the oligotrophic waters of the Red Sea to increase steeply with ambient levels of solar radiation in the Red Sea. Responses curves linking solar radiation doses with zooplankton mortality were evaluated by exposing organisms, enclosed in quartz bottles, allowing all the wavelengths of solar radiation to penetrate, to five different levels of ambient solar radiation (100%, 21.6%, 7.2%, 3.2% and 0% of solar radiation. The maximum mortality rates under ambient solar radiation levels averaged (±standard error of the mean, SEM 18.4±5.8% h(-1, five-fold greater than the average mortality in the dark for the eight taxa tested. The UV-B radiation required for mortality rates to reach ½ of maximum values averaged (±SEM 12±5.6 h(-1% of incident UVB radiation, equivalent to the UV-B dose at 19.2±2.7 m depth in open coastal Red Sea waters. These results confirm that Red Sea zooplankton are highly vulnerable to ambient solar radiation, as a consequence of the combination of high incident radiation and high water transparency allowing deep penetration of damaging UV-B radiation. These results provide evidence of the significance of ambient solar radiation levels as a stressor of marine zooplankton communities in tropical, oligotrophic waters. Because the oligotrophic ocean extends across 70% of the ocean surface, solar radiation can be a globally-significant stressor for the ocean ecosystem, by constraining zooplankton use of the upper levels of the water column and, therefore, the efficiency of food transfer up the food web in the oligotrophic ocean.

  13. Evaluation of the role of damage to photosystem II in the inhibition of CO2 assimilation in pea leaves on exposure to UV-B radiation

    International Nuclear Information System (INIS)

    Mature pea (Pisum sativum L., cv. Meteor) leaves were exposed to two levels of UV-B radiation, with and without supplementary UV-C radiation, during 15 h photoperiods. Simultaneous measurements of CO2 assimilation and modulated chlorophyll fluorescence parameters demonstrated that irradiation with UV-B resulted in decreases in CO2 assimilation that are not accompanied by decreases in the maximum quantum efficiency of photosystem II (PSII) primary photochemistry. Increased exposure to UV-B resulted in a further loss of CO2 assimilation and decreases in the maximum quantum efficiency of PSII primary photochemistry, which were accompanied by a loss of the capacity of thylakoids isolated from the leaves to bind atrazine, thus demonstrating that photodamage to PSII reaction centres had occurred. Addition of UV-C to the UV-B treatments increased markedly the rate of inhibition of photosynthesis, but the relationships between CO2 assimilation and PSII characteristics remained the same, indicating that UV-B and UV-C inhibit leaf photosynthesis by a similar mechanism. It is concluded that PSII is not the primary target site involved in the onset of the inhibition of photosynthesis in pea leaves induced by irradiation with UV-B. (author)

  14. Carbon allocation from source to sink leaf tissue in relation to flavonoid biosynthesis in variegated Pelargonium zonale under UV-B radiation and high PAR intensity.

    Science.gov (United States)

    Vidović, Marija; Morina, Filis; Milić, Sonja; Albert, Andreas; Zechmann, Bernd; Tosti, Tomislav; Winkler, Jana Barbro; Jovanović, Sonja Veljović

    2015-08-01

    We studied the specific effects of high photosynthetically active radiation (PAR, 400-700 nm) and ecologically relevant UV-B radiation (0.90 W m(-2)) on antioxidative and phenolic metabolism by exploiting the green-white leaf variegation of Pelargonium zonale plants. This is a suitable model system for examining "source-sink" interactions within the same leaf. High PAR intensity (1350 μmol m(-2) s(-1)) and UV-B radiation induced different responses in green and white leaf sectors. High PAR intensity had a greater influence on green tissue, triggering the accumulation of phenylpropanoids and flavonoids with strong antioxidative function. Induced phenolics, together with ascorbate, ascorbate peroxidase (APX, EC 1.11.1.11) and catalase (CAT, EC 1.11.1.6) provided efficient defense against potential oxidative pressure. UV-B-induced up-regulation of non-phenolic H2O2 scavengers in green leaf sectors was greater than high PAR-induced changes, indicating a UV-B role in antioxidative defense under light excess; on the contrary, minimal effects were observed in white tissue. However, UV-B radiation had greater influence on phenolics in white leaf sections compared to green ones, inducing accumulation of phenolic glycosides whose function was UV-B screening rather than antioxidative. By stimulation of starch and sucrose breakdown and carbon allocation in the form of soluble sugars from "source" (green) tissue to "sink" (white) tissue, UV-B radiation compensated the absence of photosynthetic activity and phenylpropanoid and flavonoid biosynthesis in white sectors. PMID:25661975

  15. Ethylene Production and 1-Aminocyclopropane-1-Carboxylate (ACC) Synthase Gene Expression in Tomato(Lycopsicon esculentum Mill.) Leaves Under Enhanced UV-B Radiation

    Institute of Scientific and Technical Information of China (English)

    Lizhe An; Xunling Wang; Xiaofeng Xu; Hongguan Tang; Manxiao Zhang; Zongdong Hou; Yanhong Liu; Zhiguang Zhao; Huyuan Feng; Shijian Xu

    2006-01-01

    Tomato (Lycopsicon esculentum Mill.) plants grown in a greenhouse were irradiated with two different levels of UV-B, namely 8.82 (T1) and 12.6 kJ/m2 per day (T2). Ethylene production, 1-aminocyclopropane-1carboxylate (ACC) content, 1-(malonylamino) cyclopvopane-1-carboxylic acid (MACC) content, gene expression of ACC synthase (EC 4.4.1.14), and ACC oxidase activity in tomato leaves were determined. The results indicated that ACC content, the activity of ACC synthase and ACC oxidase, and ethylene production increased continuously under low doses of UV-B radiation, whereas at high doses of radiation these parameters increased during the first 12 d and then started to decrease. The MACC content increased continuously over 18 d under both doses of UV-B irradiation. The changes in ACC content, ACC synthase activity,ACC oxidase activity, the transcriptional level of the ACC synthase gene, and ethylene production were consistent with each other, suggesting that ACC synthase was the key enzyme in ethylene biosynthesis and that ethylene production in tomato leaf tissues under UV-B radiation could be regulated by the expression of the ACC synthase gene. The results also indicate that the change in ethylene metabolism may be an adaptive mechanism to enhanced UV-B radiation.

  16. UV-B辐射胁迫下杨梅幼苗的高光谱响应%High-spectral responses of Myrica rubra seedlings to UV-B radiation stress

    Institute of Scientific and Technical Information of China (English)

    金鑫杰; 江洪; 陈健; 时启龙; 张倩倩

    2012-01-01

    A simulated field experiment with three treatments, i. e. , ambient light ( control) , reduced UV-B radiation, and enhanced UV-B radiation, was conducted to evaluate the effects of solar ultraviolet ( UV-B) radiation on the seedlings of Myrica rubra, a typical woody species in subtropical region. The leaf chlorophyll content, spectral reflectance and spectral characteristic parameters were measured and analyzed. As compared with the control, enhanced UV-B radiation decreased the seedling chlorophyll content while reduced UV-B radiation significantly increased the chlorophyll content, and these effects reflected in the spectral reflectance. Under the effects of the three gradients of UV-B radiation, the differences in the reflectance at visible region mainly occurred around the green peak and red edge on the reflectance curve, and the peak wavelength of the red edge shifted to longer wavelength. Enhanced UV-B radiation had an accumulated temporal effect on M. rubra. The inverted-Gaussian model parameters R0, λ0, λp, Rs, and 6 were the useful guides to reveal the spectral responses of M. rubra seedlings under UV-B radiation stress, among which, R8 performed the best. The differences in the spectral reflectance under different UV-B radiation levels could be effectively distinguished with the vegetation indices composed of the spectral reflectance of narrow wave bands or the reflectance at specific wavelengths.%设置UV-B滤光减弱、UV-B辐射增强和自然光(对照)3组模拟大田试验,比较了不同UV-B辐射处理下,亚热带典型木本植物杨梅幼苗的叶绿素含量、光谱反射率及光谱特征参数,研究UV-B辐射变化对亚热带森林树种的影响.结果表明:增强UV-B辐射可降低杨梅幼苗的叶绿素含量,而降低辐射则会显著促进叶绿素的增加,并且这种胁迫反应于光谱反射率中.3种不同梯度UV-B辐射作用下,可见光部分光谱反射率间的差异主要集中在绿光反射峰及红边附近,

  17. Ambient UV-B exposure reduces the binding of ofloxacin with bacterial DNA gyrase and induces DNA damage mediated apoptosis.

    Science.gov (United States)

    Singh, Jyoti; Dwivedi, Ashish; Mujtaba, Syed Faiz; Singh, Krishna P; Pal, Manish Kumar; Chopra, Deepti; Goyal, Shruti; Srivastav, Ajeet K; Dubey, Divya; Gupta, Shailendra K; Haldar, Chandana; Ray, Ratan Singh

    2016-04-01

    Ofloxacin (OFLX) is a broad spectrum antibiotic, which generates photo-products under sunlight exposure. Previous studies have failed to explain the attenuated anti-bacterial activity of OFLX. The study was extended to explore the unknown molecular mechanism of photogenotoxicity on human skin cell line (HaCaT) under environmental UV-B irradiation. Photochemically OFLX generates ROS and caused 2'-dGuO photodegradation. We have addressed the binding affinity of OFLX and its photo-products against DNA gyrase. Significant free radical generation such as (1)O2, O2(•-) and (•)OH reduces antioxidants and demonstrated the ROS mediated OFLX phototoxicity. However, the formation of micronuclei and CPDs showed photogenotoxic potential of OFLX. OFLX induced cell cycle arrest in sub-G1 peak. OFLX triggers apoptosis via permeabilization of mitochondrial membrane with the downregulation of anti-apoptotic Bcl-2 and caspase-3 whereas, upregulation of pro-apoptotic Bax and Cyto-C proteins. Our study illustrated that binding affinity of OFLX photo-products with DNA gyrase was mainly responsible for the attenuated antimicrobial activity. It was proved through molecular docking study. Thus, study suggests that sunlight exposure should avoid by drug users especially during peak hours for their safety from photosensitivity. Clinicians may guide patients regarding the safer use of photosensitive drugs during treatment. PMID:26812543

  18. RESPONSES IN NITROGEN MASS AND NITROGEN METABOLISM OF WILD SUGARCANE (SACCHARUM SPONTANEUM L.) CLONES TO ENHANCED UV-B RADIATION UNDER FIELD CONDITIONS

    OpenAIRE

    Yanqun Zu; Yuan Li; Haiyun Wang; Yongmei He

    2013-01-01

    Field experiments were conducted to evaluate effects of enhanced UV-B radiation (280-315 nm) on intraspecific responses in nitrogen mass and nitrogen metabolism of six wild sugarcane (Saccharum spontaneum L.) clones. The clones were collected from original sites with different altitudes (4-1780 m above sea-level) and latitudes (18-38°N). The supplemental UV-B radiation was 5.00 kJâ¢m-2, simulating a depletion of 20% stratospheric ozone. Out of the six tested wild sugarcane clones, available ...

  19. The effect of UV-B and UV-C radiation on Hibiscus leaves determined by ultraweak luminescence and fluorescence induction [chlorophyll fluorescence induction, ultraweak luminescence

    International Nuclear Information System (INIS)

    The effects of UV-C (254 nm) and UV-B (280-320 nm) on chlorophyll fluorescence induction and ultraweak luminescence (UL) in detached leaves of Hibiscus rosa-sinensis L. were investigated. UL from leaves exposed to UV-B and UV-C radiation reached a maximum 72 h after irradiation. In both cases most of the light was of a wavelength over 600 nm. An increase in the percentage of long wavelength light with time was detected. UV radiation increased peroxidase activity, which also reached a maximum 72 h after irradiation. UV-B and UV-C both reduced variable chlorophyll fluorescence. No effect on the amount of chlorophyll or UV screening pigments was observed with the short-term irradiation used in this investigation. (author)

  20. Effects of UV-B Radiation Levels on Concentrations of Phytosterols, Ergothioneine, and Polyphenolic Compounds in Mushroom Powders Used As Dietary Supplements.

    Science.gov (United States)

    Sapozhnikova, Yelena; Byrdwell, William Craig; Lobato, Amada; Romig, Bill

    2014-03-27

    Compositional changes of powder dietary supplements made from mushrooms exposed to different levels of UV-B irradiation were evaluated for the bioactive naturally occurring mushroom antioxidant, ergothioneine; other natural polyphenolic compounds, e.g., flavonoids, lignans, etc.; and selected phytosterols. Four types of mushroom powder consisting of white, brown (Agaricus bisporus), oyster (Pleurotus ostreatus), and shiitake (Lentinula edodes) mushrooms from three different treatment groups (control, low and high UV-B exposures) were evaluated. Ergothioneine concentrations found in mushroom powders were 0.4-10.4 mg/g dry weight (dw) and were not appreciably affected by UV-B radiation. No individual polyphenols were detected above 0.1 μg/g. Phytosterols ergosterol (2.4-6.2 mg/g dw) and campesterol (14-43 μg/g dw) were measured in mushroom powder samples. Ergosterol concentrations decreased significantly with the increased level of UV-B treatment for all mushroom powder types, except for white. These results provide some new information on effects of UV-B radiation on these important natural bioactive compounds in mushrooms.

  1. Effects of salicylic acid (SA), ultraviolet radiation (UV-B and UV-C) on trans-resveratrol inducement in the skin of harvested grape berries

    Institute of Scientific and Technical Information of China (English)

    Xiaodong LI; Xianbo ZHENG; Shutang YAN; Shaohua LI

    2008-01-01

    Effects of salicylic acid (SA), ultraviolet radiation (UV-B and UV-C) on the trans-resveratrol (Res) inducement of the skin of harvested grape berries were studied with three grape cultivars Takasuma, Tano Red and Carigane. Split plot design tests were adopted to compare the effects of UV-B and UV-C radiation on Res inducement of different cultivars. Results showed that tents in the skins of harvested berries for the three-selected cultivars. However, the effect of SA varied with the cultivars, and Res inducement by SA was more effective to Tano Red than Takasuma and Carigane. UV-B or UV-C irradiation significantly increased Res contents in grape skins and UV-C was more effective than UV-B. The effects of UV types and dosages on Res inducement depended upon cultivars. In the range of 0-3.6 kJ.m-2, the Res contents in the skins of the three grape cultivars were enhanced along with the increase of dosages of UV-B and UV-C.

  2. Long-term structural canopy changes sustain net photosynthesis per ground area in high arctic Vaccinium uliginosum exposed to changes in near-ambient UV-B levels

    DEFF Research Database (Denmark)

    Boesgaard, Kristine Stove; Albert, Kristian Rost; Ro-Poulsen, Helge;

    2012-01-01

    Full recovery of the ozone layer is not expected for several decades and consequently, the incoming level of solar ultraviolet-B (UV-B) will only slowly be reduced. Therefore to investigate the structural and photosynthetic responses to changes in solar UV-B we conducted a 5-year UV-B exclusion...

  3. Effects of stron UV-B radiation on air chemistry and climate; Auswirkungen verstaerkter UV-B-Strahlung auf Luftchemie und Klima

    Energy Technology Data Exchange (ETDEWEB)

    Schoenemeyer, T.; Seidl, W.; Forkel, R.; Kuhn, M.; Wehrhahn, J.; Grell, G.

    1998-07-01

    Effects of enhanced UV radiation on air chemistry, climate and climate change were investigated, and its interactions with other environmental problems like acidification of soil and surface water, reduction in the variety of species, and desertification were gone into. [German] In der vorliegenden Arbeit wurden die bisher vorliegenden Erkenntnisse ueber die Auswirkungen erhoehter UV-Strahlung infolge des Abbaus von Ozon in der Stratosphaere auf Luftchemie und Klima zusammengetragen. Die Problematik wird in ihrer ganzen Breite beleuchtet und dabei deutlich gemacht, ueber welche zahlreichen Mechanismen eine erhoehte UV-Strahlung auch zu Klimaaenderungen fuehren kann. Dies unterstreicht die Notwendigkeit, Verknuepfungen mit anderen Umweltproblemen wie der Versauerung des Bodens und von Gewaessern, der Abnahme der Artenvielfalt sowie der zunehmenden Wuestenbildung herzustellen. (orig.)

  4. Effects of solar UV-B radiation on canopy structure of Ulva communities from southern Spain

    NARCIS (Netherlands)

    Bischof, K; Peralta, G; Krabs, G; van de Poll, WH; Perez-Llorens, JL; Breeman, AM

    2002-01-01

    Within the sheltered creeks of Cadiz bay, Ulva thalli form extended mat-like canopies. The effect of solar ultraviolet radiation on photosynthetic activity, the composition of photosynthetic and xanthophyll cycle pigments, and the amount of RubisCO, chaperonin 60 (CPN 60), and the induction of DNA d

  5. Effects of solar UV-B radiation on canopy structure of Ulva communities from southern Spain

    NARCIS (Netherlands)

    Bischof, K.; Peralta, G.; Kräbs, G.; van de Poll, W.H.; Lucas Pérez-Lloréns, J.; Breeman, A.M.

    2002-01-01

    Within the sheltered creeks of Cádiz bay, Ulva thalli form extended mat-like canopies. The effect of solar ultraviolet radiation on photosynthetic activity, the composition of photosynthetic and xanthophyll cycle pigments, and the amount of RubisCO, chaperonin 60 (CPN 60), and the induction of DNA d

  6. Ultraviolet-B (UV-B) radiation as an elicitor of flavonoid production in callus cultures of jatropha (Jatropha curcas L.)

    International Nuclear Information System (INIS)

    Callus cultures of jatropha (Jatropha curcas L.) grown in Murashige and Skoog's (MS) medium supplemented with naphthalene-acetic acid (NAA, 20 microM) and 6-furfurylaminopurine (kinetin, 20 microM) were exposed to ultraviolet-B (UV-B) radiation to investigate its potential as an abiotic elicitor of flavonoid production. Prior to irradiation, the levels of the flavonoids, apigenin, vitexin and isovitexin in the leaf and callus extracts were determined through high performance liquid chromatography (HPLC). Results showed that vitexin and isovitexin were the dominant flavonoids in the leaves while only apigenin was detected in the calli, suggesting a correlation between the degree of differentiation and biosynthesis of flavonoids in plant tissues. Irradiation of callus cultures for 7 d using two UV-B doses (12.6 and 25.3 kJ/sq m) induced synthesis of all three flavonoids (up to 780 micro g/g dw increase) to levels similar to or higher than those found in whole leaves. The combined levels of the three flavonoids in the cultures treated with the higher UV-B dose were 20-fold higher than the control and were comparable to concentrations found in leaves while a 10-fold increase in combined flavonoid levels was observed in calli irradiated with the lower UV-B dose. Furthermore, random amplified polymorphic DNA (RAPD) analyses of DNA extracts from the leaves and calli revealed that UV-B irradiation enhanced flavonoid synthesis without altering DNA sequence. These results further support the supposed involvement of UV-B in the transcriptional regulation of the expression of flavonoid biosysnthetic genes. Overall, the findings showed that elicitation through UV-B irradiation is an effective strategy to induce flavonoid production in dedifferentiated J. curcas cultures that have lost their capacity to produce the flavonoids normally synthesized in intact organs. (author)

  7. Research on the Signals of Cotton in Response to UV-B Radiation%棉花响应UV-B辐射的信号初探

    Institute of Scientific and Technical Information of China (English)

    侍福梅; 孟慧敏; 王超

    2011-01-01

    Phenotype and hydrogen peroxide and nitric oxide were studied in three kinds of cotton under ultraviolet-B (UV-B) radiation with or without SNP and ABA treatment. The results indicated that leaves of cotton seedlings showed obvious rust, and leaves in vitro dehydrate apparently suffering UV-B stress, Pretreatment with sudium nitroprusside (SNP) and abscisic acid (ABA) lightened rust and wilt symptom of the leaves due to UV-B radiation. Both hydrogen peroxide (H2 O2) dyed with 3, 3-diaminobenzidine (DAB) and nitric oxide (NO) labelled by 4,5-diaminofluorescein diacetate (DAF-2DA) were increased after UV-B radiation than untreated control. And the release of NO alleviated the damage from UV-B radiation by reducing the accumulation of H2O2. In additon, pretreatment with ABA significantly increased the tolerance of cotton, which is bound up with the production of R2O2 and NO. Therefore, UV-B radiation caused damage of cotton during the growth and development , and all of H2 O2, NO and ABA are members of the signal transduction during the interaction between cotton and UV-B stress.%以3种棉花为供试材料,研究紫外线-B(UV-B)辐射及外源SNP、ABA叠加处理对棉花幼苗表观形态及内源H2O2与NO水平的影响.结果表明,UV-B辐射引起棉花幼苗叶片呈现锈色伤斑,离体叶片明显失水萎蔫.叶片外源涂抹SNP、ABA能减轻UV-B辐射引起的幼叶伤斑与萎蔫症状,缓解UV-B辐射所造成的伤害.DAB及DAF-2DA染色结果显示,UV-B辐射引起棉花内源H2O2与NO含量增加,面NO的释放通过减少H2O2积累减轻紫外辐射对棉花的伤害.ABA预处理可增强棉花对紫外伤害的耐受能力,且与H2O2与NO的释放密切相关.UV-B辐射对棉花生长造成伤害,H2O2、NO及ABA都参与棉花应答UV-B胁迫的信号转导过程.

  8. Differences of UV-B radiation sensitivity of rice%水稻对UV-B辐射响应的敏感性差异

    Institute of Scientific and Technical Information of China (English)

    何永美; 湛方栋; 高召华; 祖艳群; 李元

    2012-01-01

    综述了UV-B辐射对水稻(Oryza sativa L.)的影响和水稻对UV-B辐射的抗性机制.UV-B辐射对水稻生长、叶片形态、生物量、产量、光合系统、病害等产生一定的影响.水稻对UV-B辐射的敏感性因子主要有CPD光解酶、UV-B吸收物质、抗氧化酶等.UV-B辐射使水稻叶片中产生了ROS,导致Rubisco酶降解,光合色素含量变化,抑制了光合作用,最终影响水稻籽粒形成和产量.水稻对UV-B辐射响应存在着品种差异,CPD光解酶编码基因的自然突变会引起水稻UV-B敏感性的差异,CPD光解酶活性是水稻对UV-B敏感性的关键因素.通过建立响应指数公式,对水稻UV-B响应敏感性的品种差异进行评估,存在品种差异的原因主要是基因、生长、生理、生育期和环境背景的差异.最后对UV-B辐射对水稻的影响、水稻对UV-B响应的差异及机理有待深入研究的方向进行了展望.%The effects and its resistance mechanisms of enhanced UV-B radiation on rice were summarized. Effect of enhance UV-B radiation on the growth, leaf shape, biomass, yield, photosynthesis system and disease of rice were reported. Cyclobutane pyrimidine dimer (CPD) photolyase, UV-B absorbing compound and antioxidant enzymes are the main factors indicated the sensitivity of rice to UV-B radiation. UV-B radiation induces reactive oxygen species (ROS) production, Rubisco enzyme decomposition, photosynthetic pigments content decrease and photosynthesis inhibition of rice leaves, and resulted in decrease in grain yield. There were species differences on rice response to UV-B radiation. Spontaneous mutation of gene encoding CPD photolyase would cause UV-B sensitivity differences in rice. CPD photolyase activity is the key factor influencing in rice sensitivity to UV-B radiation. Species differences of rice response to UV-B radiation could be assessed by the response index. The differences in species mainly are due to genes, growth, physiology, reproductive

  9. Physiological responses and molecular mechanism of rice (Oryza sativa)exposed to enhanced UV-B radiation%水稻对UV-B辐射增强的生理响应及其分子机制研究

    Institute of Scientific and Technical Information of China (English)

    林文雄

    2013-01-01

    本文以水稻为研究对象,从细胞、个体和群体水平系统分析了不同水稻品种对UV-B辐射增强差异响应的遗传生理与防卫机制.试从农业生态系统角度,结合作者近期研究成果,系统分析了近年来国内外的研究重点及其成就.已有研究认为水稻对UV-B辐射增强的生理响应存在明显的种间差异,通常认为起源于靠近赤道附近的低纬度地区的籼稻品种比高纬度地区的粳稻品种更抗(耐)UV-B辐射污染,但许多研究结果不支持这一假说,即在籼粳稻品种中均存在明显对UV-B辐射增强呈不同抗性的种质资源.进一步研究结果表明水稻对UV-B辐射的响应差异是可遗传的数量性状.QTL定位分析结果发现多数抗UV-B辐射相关性状的加性QTL主要集中在第1、2、3、6染色体上,并检测到一些加性QTL还存在加性×加性上位性及其与环境的显著互作效应.作者还深入分析了水稻抗UV-B辐射增强的分子生理与调控机制,提出适当增加植物的硅营养,可以有效提高其抗逆性.最后,作者提出从农田生态系统角度研究和评价UV-B辐射增强所带来的生态风险及其影响是今后研究的重点,强调应重视研究田间条件下UV-B辐射增强及其与其他生态环境因子的互作对作物生长发育的综合影响,在此基础上,探索建立作物遗传改良与栽培调控的减灾防灾技术,为应对全球环境变化,制订相关防护策略提供理论依据和技术支撑.%In this paper, the genetic physiology and defense mechanism to enhanced UV-B radiation were reviewed at cellular, individual and population levels of rice. Analysis and achievements of recent researches in this field under combined agro-ecosystem approach and research observations were explained. Significant differences in the responses of rice germplasms to enhanced UV-B radiation had been reported. Since ambient UV-B radiation level at lower latitudes was greater than that

  10. Ectopic expression of ubiquitin-conjugating enzyme gene from wild rice, OgUBC1, confers resistance against UV-B radiation and Botrytis infection in Arabidopsis thaliana

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, En Hee; Pak, Jung Hun; Kim, Mi Jin; Kim, Hye Jeong [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of); Shin, Sang Hyun [National Crop Experiment Station, Rural Development Administration, Suwon 441-100 (Korea, Republic of); Lee, Jai Heon; Kim, Doh Hoon; Oh, Ju Sung [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of); Oh, Boung-Jun [BioControl Center, Jeonnam 516-942 (Korea, Republic of); Jung, Ho Won, E-mail: hwjung@dau.ac.kr [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of); Chung, Young Soo, E-mail: chungys@dau.ac.kr [Department of Genetic Engineering, Dong-A University, Busan 604-714 (Korea, Republic of)

    2012-10-19

    Highlights: Black-Right-Pointing-Pointer We isolated a novel E2 ubiquitin-conjugating enzyme from leaves of wild rice plants. Black-Right-Pointing-Pointer The OgUBC1 was highly expressed in leaves treated with SA and UV-B radiation. Black-Right-Pointing-Pointer The recombinant OgUBC1 has an enzymatic activity of E2 in vitro. Black-Right-Pointing-Pointer The OgUBC1 could protect disruption of plant cells by UV-B radiation. Black-Right-Pointing-Pointer OgUBC1 confers disease resistance and UV-B tolerance in transgenic Arabidopsis plants. -- Abstract: A previously unidentified gene encoding ubiquitin-conjugating enzyme was isolated from leaves of wild rice plant treated with wounding and microbe-associated molecular patterns. The OgUBC1 gene was composed of 148 amino acids and contained a typical active site and 21 ubiquitin thioester intermediate interaction residues and 4 E3 interaction residues. Both exogenous application of salicylic acid and UV-B irradiation triggered expression of OgUBC1 in leaves of wild rice. Recombinant OgUBC1 proteins bound to ubiquitins in vitro, proposing that the protein might act as E2 enzyme in planta. Heterologous expression of the OgUBC1 in Arabidopsis thaliana protected plants from cellular damage caused by an excess of UV-B radiation. A stable expression of chalcone synthase gene was detected in leaves of OgUBC1-expressing Arabidopsis, resulting in producing higher amounts of anthocyanin than those in wild-type Col-0 plants. Additionally, both pathogenesis-related gene1 and 5 were transcribed in the transgenic Arabidopsis in the absence of pathogen infection. The OgUBC1-expressing plants were resistant to the infection of Botrytis cinerea. Taken together, we suggested that the OgUBC1 is involved in ubiquitination process important for cellular response against biotic and abiotic stresses in plants.

  11. Analysis of the P1 promoter in response to UV-B radiation in allelic variants of high-altitude maize

    Directory of Open Access Journals (Sweden)

    Rius Sebastián

    2012-06-01

    Full Text Available Abstract Background Plants living at high altitudes are typically exposed to elevated UV-B radiation, and harbor mechanisms to prevent the induced damage, such as the accumulation of UV-absorbing compounds. The maize R2R3-MYB transcription factor P1 controls the accumulation of several UV-B absorbing phenolics by activating a subset of flavonoid biosynthetic genes in leaves of maize landraces adapted to high altitudes. Results Here, we studied the UV-B regulation of P1 in maize leaves of high altitude landraces, and we investigated how UV-B regulates P1binding to the CHS promoter in both low and high altitude lines. In addition, we analyzed whether the expansion in the P1 expression domain between these maize landraces and inbred lines is associated to changes in the molecular structure of the proximal promoter, distal enhancer and first intron of P1. Finally, using transient expression experiments in protoplasts from various maize genotypes, we investigated whether the different expression patterns of P1 in the high altitude landraces could be attributed to trans- or cis-acting elements. Conclusions Together, our results demonstrate that, although differences in cis-acting elements exist between the different lines under study, the different patterns of P1 expression are largely a consequence of effects in trans.

  12. 拟南芥芥子酸酯对UV-B辐射的响应%Response of sinapate esters in Arabidopsis thaliana to UV-B radiation

    Institute of Scientific and Technical Information of China (English)

    李敏; 王垠; 牟晓飞; 王洋; 阎秀峰

    2012-01-01

    芥子酸酯(sinapate esters)是拟南芥和其他十字花科植物中大量存在的一类具有紫外吸收作用的羟基肉桂酸衍生物,有研究表明其紫外吸收能力甚至强于类黄酮.以模式植物拟南芥(Arabidopsis thaliana)为实验材料,通过施加低强度(40 μW/cm2)、相对长时间(7 d)的UV-B辐射,考察了拟南芥幼苗和成苗芥子酸酯组分(芥子酰葡萄糖、芥子酰苹果酸)和含量及合成途径关键酶编码基因表达水平对UV-B辐射的响应.经过7d的UV-B辐射处理,拟南芥幼苗和成苗的芥子酰葡萄糖、芥子酰苹果酸含量均高于对照植株,芥子酸酯表现为响应UV-B辐射而积累.无论是幼苗还是成苗,叶片中芥子酰苹果酸的含量都要比芥子酰葡萄糖高出一个数量级,而且在UV-B处理过程中观察到芥子酰葡萄糖含量减少而芥子酰苹果酸含量增加,催化芥子酰葡萄糖生成芥子酰苹果酸的芥子酰葡萄糖苹果酸转移酶编码基因的表达水平也显著提高,说明芥子酰苹果酸在拟南芥叶片响应UV-B辐射过程中起重要作用并优先合成.另外,拟南芥幼苗中两种芥子酸酯的含量是成苗中的数十倍之多,芥子酸酯合成途径关键酶编码基因fah1和sng1的相对表达量也显著高于成苗.同时,在响应UV-B辐射的过程中,幼苗中芥子酰葡萄糖、芥子酰苹果酸含量的变化幅度(分别是7.01%、6.05%)远远低于成苗叶片中芥子酰葡萄糖、芥子酰苹果酸含量的变化幅度(分别是21.88%、70.63%),这可能意味着拟南芥叶片中芥子酸酯对于UV-B辐射的防护作用,幼苗属于组成型防御(constitutive defense),而到成苗则转变为诱导型防御(inducible defense).%The impact of UV-B radiation (280 to 320 nm) at the earth's surface is predicted to increase because of the anthropogenic depletion of stratospheric ozone caused by industrial emissions of atmospheric pollutants. Plant growth and productivity are compromised

  13. Differential physiological and biochemical responses of two cyanobacteria Nostoc muscorum and Phormidium foveolarum against oxyfluorfen and UV-B radiation.

    Science.gov (United States)

    Sheeba; Pratap Singh, Vijay; Kumar Srivastava, Prabhat; Mohan Prasad, Sheo

    2011-10-01

    In the present study, degree of tolerance and tolerance strategies of two paddy field cyanobacteria viz. Nostoc muscorum and Phormidium foveolarum against oxyfluorfen (10 and 20 μg ml(-1)) and UV-B (7.2 kJ m(-2)d(-1)) stress were investigated. Oxyfluorfen and UV-B decreased growth, photosynthesis, nutrient uptake, nitrate reductase, acid and alkaline phosphatase activities, which accompanied with the increase in the level of oxidative stress. However, growth was more affected in N. muscorum than P. foveolarum. Antioxidants exhibited differential responses against oxyfluorfen and UV-B stress. Ascorbate and proline levels were higher in P. foveolarum. A protein of 66 kDa was expressed in N. muscorum, however, it was absent in P. foveolarum than those of N. muscorum. Besides this, a protein of 29 kDa appeared in P. foveolarum under all the treatments, but it was present only in control cells of N. muscorum cells. Overall results indicated resistant nature of P. foveolarum against oxyfluorfen and UV-B stress in comparison to N. muscorum. PMID:21798597

  14. Effects of enhanced UV-B radiation in combination with other stress factors on the growth and function of agricultural plants

    International Nuclear Information System (INIS)

    Measurements of variable fluorescence, oxygen production and absorption changes suggested that the reaction centers of photosystem II are inhibited by UV-B radiation and, at the same time, are changed into dissipative sinks for the excitation energy. Selective impairment of water splitting is excluded as a cause of the inhibition of the primary processes of photosynthesis. The activity of photosystem I is not affected. (orig./AJ)

  15. Level of UV-B radiation influences the effects of glyphosate-based herbicide on the spotted salamander.

    Science.gov (United States)

    Levis, Nicholas A; Johnson, Jarrett R

    2015-07-01

    Glyphosate-based herbicides are the number one pesticide in the United States and are used commonly around the world. Understanding the affects of glyphosate-based herbicides on non-target wildlife, for example amphibians, is critical for evaluation of regulations pertaining to the use of such herbicides. Additionally, it is important to understand how variation in biotic and abiotic environmental conditions, such as UV-B light regime, could potentially affect how glyphosate-based herbicides interact with non-target species. This study used artificial pond mesocosms to identify the effects of generic glyphosate-based herbicide (GLY-4 Plus) on mortality, cellular immune response, body size, and morphological plasticity of larvae of the spotted salamander (Ambystoma maculatum) under conditions that reflect moderate (UV(M)) and low (UV(L)) UV-B light regimes. Survival within a given UV-B level was unaffected by herbicide presence or absence. However, when herbicide was present, survival varied between UV-B levels with higher survival in UV(M) conditions. Herbicide presence in the UV(M) treatments also decreased body size and reduced cellular immune response. In the UV(L) treatments, the presence of herbicide increased body size and affected tail morphology. Finally, in the absence of herbicide, body size and cellular immune response were higher in UV(M) treatments compared to UV(L) treatments. Thus, the effects of herbicide on salamander fitness were dependent on UV-B level. As anthropogenic habitat modifications continue to alter landscapes that contain amphibian breeding ponds, salamanders may increasingly find themselves in locations with reduced canopy cover and increased levels of UV light. Our findings suggest that the probability of surviving exposure to the glyphosate-based herbicide used in this study may be elevated in more open canopy ponds, but the effects on other components of fitness may be varied and unexpected. PMID:25794558

  16. UV-B辐射增强及种植密度对大麦生长发育的影响%Effects of planting density and enhanced UV-B radiation on growth and development of barley

    Institute of Scientific and Technical Information of China (English)

    朱婷婷; 娄运生; 黄岩

    2013-01-01

    A field experiment was conducted to investigate the effects of enhanced UV-B radiation and different planting densities on growth and development of barley. The experiment was designed with four levels of UV-B radiation i. e. control (CK, ambient) , enhanced UV-B (El , enhanced 10% ) , enhanced UV-B (E2, 20% enhanced) and enhanced UV-B (E3, 30% enhanced) and with three levels of planting densities i.e. 5.56 g/m2 ( D1 ) , 11. 11 g/m2 ( D2) and 16.67 g/m2 (D3). The results showed that the decreases in plant height, green leaf area and biomass (root and shoot) decreased under enhanced UV-B radiation, and the stronger the radiation, the more obvious the inhibition. The inhibition varied with growth stages. Under natural light, increasing planting density led to the increase in plant height and the decreases in green leaf area and biomass. Under enhanced UV-B treatment E2, the inhibition could be alleviated by increasing planting density.%在大田条件下研究了不同UV-B辐射强度及种植密度对大麦生长发育的影响.UV-B辐射强度设4个水平,即对照(自然光)、E1(比对照增强10%)、E2(比对照增强20%)和E3(比对照增强30%);种植密度(播种量)设3个水平,即D1(5.56 g/m2)、D2(11.11g/m2)和D3(16.67g/m2).结果表明,UV-B辐射增强明显抑制大麦生长,使植株变矮,绿叶面积和干物质量下降,且辐射越强,抑制作用越明显,但抑制程度随生育期而异.在自然光下,增大种植密度可使株高增加,绿叶面积和干物质量下降;UV-B辐射增强20%处理下,增大种植密度可减轻UV-B辐射增强对大麦生长的抑制作用.在UV-B辐射增强条件下,适当提高大麦种植密度,可降低UV-B辐射增强对大麦生长的不利影响.

  17. Constitutive or Inducible Protective Mechanisms against UV-B Radiation in the Brown Alga Fucus vesiculosus? A Study of Gene Expression and Phlorotannin Content Responses.

    Directory of Open Access Journals (Sweden)

    Emeline Creis

    Full Text Available A role as UV sunscreens has been suggested for phlorotannins, the phenolic compounds that accumulate in brown algae in response to a number of external stimuli and take part in cell wall structure. After exposure of the intertidal brown alga Fucus vesiculosus to artificial UV-B radiation, we examined its physiological responses by following the transcript level of the pksIII gene encoding a phloroglucinol synthase, likely to be involved in the first step of phlorotannins biosynthesis. We also monitored the expression of three targeted genes, encoding a heat shock protein (hsp70, which is involved in global stress responses, an aryl sulfotransferase (ast, which could be involved in the sulfation of phlorotannins, and a vanadium bromoperoxidase (vbpo, which can potentially participate in the scavenging of Reactive Oxygen Species (ROS and in the cross-linking and condensation of phlorotannins. We investigated whether transcriptional regulation of these genes is correlated with an induction of phlorotannin accumulation by establishing metabolite profiling of purified fractions of low molecular weight phlorotannins. Our findings demonstrated that a high dose of UV-B radiation induced a significant overexpression of hsp70 after 12 and 24 hours following the exposure to the UV-B treatment, compared to control treatment. The physiological performance of algae quantified by the photosynthetic efficiency (Fv/Fm was slightly reduced. However UV-B treatment did not induce the accumulation of soluble phlorotannins in F. vesiculosus during the kinetics of four weeks, a result that may be related to the lack of induction of the pksIII gene expression. Taken together these results suggest a constitutive accumulation of phlorotannins occurring during the development of F.vesiculosus, rather than inducible processes. Gene expression studies and phlorotannin profiling provide here complementary approaches to global quantifications currently used in studies of

  18. Changes in dissolved organic material determine exposure of stream benthic communities to UV-B radiation and heavy metals: Implications for climate change

    Science.gov (United States)

    Clements, W.H.; Brooks, M.L.; Kashian, D.R.; Zuellig, R.E.

    2008-01-01

    Changes in regional climate in the Rocky Mountains over the next 100 years are expected to have significant effects on biogeochemical cycles and hydrological processes. In particular, decreased discharge and lower stream depth during summer when ultraviolet radiation (UVR) is the highest combined with greater photo-oxidation of dissolved organic materials (DOM) will significantly increase exposure of benthic communities to UVR. Communities in many Rocky Mountain streams are simultaneously exposed to elevated metals from abandoned mines, the toxicity and bioavailability of which are also determined by DOM. We integrated field surveys of 19 streams (21 sites) along a gradient of metal contamination with microcosm and field experiments conducted in Colorado, USA, and New Zealand to investigate the influence of DOM on bioavailability of heavy metals and exposure of benthic communities to UVR. Spatial and seasonal variation in DOM were closely related to stream discharge and significantly influenced heavy metal uptake in benthic organisms. Qualitative and quantitative changes in DOM resulting from exposure to sunlight increased UV-B (290-320nm) penetration and toxicity of heavy metals. Results of microcosm experiments showed that benthic communities from a metal-polluted stream were tolerant of metals, but were more sensitive to UV-B than communities from a reference stream. We speculate that the greater sensitivity of these communities to UV-B resulted from costs associated with metal tolerance. Exclusion of UVR from 12 separate Colorado streams and from outdoor stream microcosms in New Zealand increased the abundance of benthic organisms (mayflies, stoneflies, and caddisflies) by 18% and 54%, respectively. Our findings demonstrate the importance of considering changes in regional climate and UV-B exposure when assessing the effects of local anthropogenic stressors. ?? Journal compilation ?? 2008 Blackwell Publishing.

  19. Intra- and interspecific differences of 10 barley and 10 tomato cultivars in response to short-time UV-B radiation: A study analysing thermoluminescence, fluorescence, gas-exchange and biochemical parameters

    International Nuclear Information System (INIS)

    The impact of UV-B radiation on 10 genotypically different barley and tomato cultivars was tested in a predictive study to screen for potentially UV-tolerant accessions and to analyze underlying mechanisms for UV-B sensitivity. Plant response was analyzed by measuring thermoluminescence, fluorescence, gas exchange and antioxidant status. Generally, barley cultivars proved to be much more sensitive against UV-B radiation than tomato cultivars. Statistical cluster analysis could resolve two barley groups with distinct differences in reaction patterns. The UV-B sensitive group showed a stronger loss in PSII photochemistry and a lower gas-exchange performance and regulation after UV-B radiation compared to the more tolerant group. The results indicate that photosynthetic light and dark reactions have to play optimally in concert to render plants more tolerant against UV-B radiation. Hence, measuring thermoluminescence/fluorescence and gas exchange in parallel will have much higher potential in identifying tolerant cultivars and will help to understand the underlying mechanisms. - Mechanisms of UV-B tolerance and sensitivity in crop plants.

  20. Mean Annual UV-B Irradiance

    Data.gov (United States)

    U.S. Environmental Protection Agency — Ultraviolet-B (UV-B) radiation is the most energetic part of sunlight reaching the Earth's surface (wavelength region is 280 to 315 nm), and it has been shown to...

  1. Depletion of stratospheric ozone over the Antarctic and Arctic: Responses of plants of polar terrestrial ecosystems to enhanced UV-B, an overview

    Energy Technology Data Exchange (ETDEWEB)

    Rozema, Jelte [Department of Systems Ecology, Institute of Ecological Science, Climate Centre, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam (Netherlands)]. E-mail: jelte.rozema@ecology.falw.vu.nl; Boelen, Peter [Department of Systems Ecology, Institute of Ecological Science, Climate Centre, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam (Netherlands); Blokker, Peter [Department of Systems Ecology, Institute of Ecological Science, Climate Centre, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam (Netherlands)

    2005-10-15

    Depletion of stratospheric ozone over the Antarctic has been re-occurring yearly since 1974, leading to enhanced UV-B radiation. Arctic ozone depletion has been observed since 1990. Ozone recovery has been predicted by 2050, but no signs of recovery occur. Here we review responses of polar plants to experimentally varied UV-B through supplementation or exclusion. In supplementation studies comparing ambient and above ambient UV-B, no effect on growth occurred. UV-B-induced DNA damage, as measured in polar bryophytes, is repaired overnight by photoreactivation. With UV exclusion, growth at near ambient may be less than at below ambient UV-B levels, which relates to the UV response curve of polar plants. UV-B screening foils also alter PAR, humidity, and temperature and interactions of UV with environmental factors may occur. Plant phenolics induced by solar UV-B, as in pollen, spores and lignin, may serve as a climate proxy for past UV. Since the Antarctic and Arctic terrestrial ecosystems differ essentially (e.g. higher species diversity and more trophic interactions in the Arctic), generalization of polar plant responses to UV-B needs caution. - Polar plant responses to UV-B may be different in the Arctic than Antarctic regions.

  2. Enhanced UV-B radiation during pupal stage reduce body mass and fat content, while increasing deformities, mortality and cell death in female adults of solitary bee Osmia bicornis.

    Science.gov (United States)

    Wasielewski, Oskar; Wojciechowicz, Tatiana; Giejdasz, Karol; Krishnan, Natraj

    2015-08-01

    The effects of enhanced UV-B radiation on the oogenesis and morpho-anatomical characteristics of the European solitary red mason bee Osmia bicornis L. (Hymenoptera: Megachilidae) were tested under laboratory conditions. Cocooned females in the pupal stage were exposed directly to different doses (0, 9.24, 12.32, and 24.64 kJ/m(2) /d) of artificial UV-B. Our experiments revealed that enhanced UV-B radiation can reduce body mass and fat body content, cause deformities and increase mortality. Following UV exposure at all 3 different doses, the body mass of bees was all significantly reduced compared to the control, with the highest UV dose causing the largest reduction. Similarly, following UV-B radiation, in treated groups the fat body index decreased and the fat body index was the lowest in the group receiving the highest dose of UV radiation. Mortality and morphological deformities, between untreated and exposed females varied considerably and increased with the dose of UV-B radiation. Morphological deformities were mainly manifested in the wings and mouthparts, and occurred more frequently with an increased dose of UV. Cell death was quantified by the Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay (DNA fragmentation) during early stages of oogenesis of O. bicornis females. The bees, after UV-B exposure exhibited more germarium cells with fragmented DNA. The TUNEL test indicated that in germarium, low doses of UV-B poorly induced the cell death during early development. However, exposure to moderate UV-B dose increased programmed cell death. In females treated with the highest dose of UV-B the vast majority of germarium cells were TUNEL-positive. PMID:24644123

  3. Effect of UV-B (290-320 nm) irradiation on growth and metabolism of cucumber cotyledons

    International Nuclear Information System (INIS)

    Cucumber (Cucumis sativus L. cv. Natsusairaku 3) seedlings were grown in a growth cabinet under UV-B (290–320 nm) irradiation (equivalent to the UV-B radiation normally incident at Tokyo, 36°N latitude, during clear sky conditions in mid-april on a weighted daily fluence basis) and a UV-B-free control condition. UV-B irradiation inhibited the growth of the cotyledons, i.e. the increase in area, and increase in fresh and dry weights of the cotyledons. The greatest inhibition rate was observed in the increase in area, causing a significant increase in specific leaf weight (the ratio of weight to area). UV-B irradiation had no significant effect on DNA and RNA contents in the cotyledons, but decreased protein content slightly. In contrast, the irradiation reduced the amounts of organic acids and soluble sugars, indicating that primary carbon metabolism was very sensitive to UV-B radiation. UV-B irradiation lowered the photosynthetic activity in the cotyledons without any effect on chlorophyll content and respiratory activity. These results indicate that UV-B radiation at the ambient level may act as a physiological stress in some UV-sensitive plants. (author)

  4. Effects of intensified UV-B radiation on growth and anatomical structure of two flue-cured tobacco cultivars%增强UV-B辐射对两个烤烟品种生长和叶片解剖结构的影响

    Institute of Scientific and Technical Information of China (English)

    何承刚; 綦世飞; 邵建平; 周冀衡; 姜华

    2012-01-01

    Effects of intensified UV-B radiation on growth and anatomical structure were studied in leaves of two flue-cured tobacco cultivars, Yunyan 87 (Y87) and Hongda (HD). Plants were exposed to UV-B radiation at ambient (as a control) , ambient plus 5. 30 kJ m-2d-1' (Tl) and ambient plus 8. 50 kj m-2d-1 (T2) levels ( simulating a 24. 65% and 39. 53% ozone depletion, respectively, at Kunming, 25?4'N, 102?3'E, at summer solstice) under field conditions. Plant height and stem diameter exposed to low UV-B radiation were the largest, whereas to high UV-B radiation were the least. Influential tendencies of UV-B radiation on intemode and plant height of HD were the same. Internode of Y87 was decreased as UV-B radiation enhanced. Length, width, and leaf area of HD were increased as UV-B radiation enhanced , whereas those of Y87 were the largest under low UV-B radiation treatment. Low UV-B radiation promoted increase in leaf area index, weight per unit leaf area, and weight per leaf of both cultivars. Compared to control, high UV-B radiation decreased weight per unit leaf area and weight per leaf of both cultivars, and increased leaf area index. Thickness of palisade tissues, leaf thickness, ratio of palisade tissues thickness to spongy and to leaf thickness under low UV-B radiation were the largest, whereas those under high UV-B radiation were the least. Change in plant height, inter-node and leaf area in response to UV-B radiation indicated that Y87 is more sensitive to UV-B stress. Low UV-B radiation can improve growth and anatomical structure of tobacco leaves.%以云南两个烤烟主栽品种云烟87和红花大金元为试验材料,模拟昆明地区24.65%和39.53%的臭氧衰减时增强的UV-B辐射(分别为T1 =5.30kJ m-2d-1和T2=8.50kJ m-2d-1),研究了大田条件下增强UV-B辐射对两个烤烟品种生长和上部叶解剖结构的影响.结果表明:增强UV-B辐射对两个烤烟品种株高和茎粗的影响都是以低UV-B辐射最大.UV-B辐射增

  5. ESTIMATION OF UV-B EXPOSURE IN AMPHIBIAN AQUATIC ENVIRONMENTS

    Science.gov (United States)

    Estimation of ultraviolet radiation B (UV-B; 280 to 320 nm wavelenghts) dose is essential for determining whether UV-B contributes to amphibian population declines and malformations. UV-B dose in wetlands is effected by location, time of day and year, atmospheric levels of ozone,...

  6. The sensitivity variability of seven species of marine microalgae to the influence of UV-B radiation

    International Nuclear Information System (INIS)

    Acute toxic experiments to 7 species of marine unicellular algae were performed under laboratory conditions. Three phenomena were observed. The relative growth rate (K) in treated groups provoked significant decrease (P 50 and 48 h car. EC50 were much higher than that of 48 h K (EC50), predicting that K was the most sensitive indicator among the three indexes. Spectrophotometric method was used to investigate the absorption in UV protion. Results showed that the absorption peaks concentrated in UV-C spectrum. The order of absorbency per 104 cells from low to high in UV-B portion was Chlorophyta > Bacillariophyta > Chrysophyta, which was concordant with the sensitivity order. The results also indicated a rough relationship between sensitivity and UV absorbency

  7. Influence of UV-B radiation on developmental changes, ethylene, CO[sub 2] flux and polyamines in cv. Doyenne d'Hiver pear shoots grown in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Predieri, S. (Consiglio Nazionale delle Ricerche, Centro Studi di Technica Frutticola, Bologna (Italy)); Krizek, D.T. (Climate Stress Laboratory, USDA, Beltsville, MD (United States)); Chien, Y. Wang (Horticultural Crops quality Laboratory, USDA, Beltsville, MD (United States)); Mirecki, R.M. (Climate Stress Laboratory, USDA, Beltsville, MD (United States)); Zimmerman, R.H. (Fruit Laboratory, USDA, Beltsville, MD (United States))

    1993-01-01

    In vitro shoots of cv. Doyenne d'Hiver pear (Pyrus communis L.) were irradiated under controlled environments for 6 h per day at 5 different levels of biologically effective UV-B radiation (UV-B[sub BE]). UV-B exposure caused a progressive increase in apical necrosis above background levels and stimulated leaf abscission. Shoots grown for 2 weeks at 7.8 mol m[sup -2] day[sup -1] of photosynthetic photon flux (PPF) and treated with 8.4 or 12.0 kJ m[sup -1] day[sup -1] UV-B[sub BE] produced up to 4 times more ethylene than those given 2.2 or 5.1 kJ m[sup -2] day[sup -1] UV-B[sub BE] or untreated controls. Exposure of shoots to 12 kJ m[sup -2] day[sup -1] of UV-B[sub BE] caused an increase in free putrescine content after 4 to 14 days of irradiation. Shoots showed a decrease in CO[sub 2] uptake after 3 days of UV-B; thereafter, they appeared to recover their photosynthetic capacity. Under typical PPF conditions used in micropropagation (90 [mu]mol m[sup -2] s[sup -1]), 8.4 kJ m[sup -2] day[sup -1] of UV-B radiation was injurious to relatively tender tissues of in vitro pear shoots; increasing the level of UV-B[sub BE] to 12 kJ m[sup -2] day[sup -1] produced even more adverse effects. (au).

  8. Evaluating the combined effects of pretilachlor and UV-B on two Azolla species.

    Science.gov (United States)

    Prasad, Sheo Mohan; Kumar, Sushil; Parihar, Parul; Singh, Anita; Singh, Rachana

    2016-03-01

    The present study assessed the comparative responses of two agronomic species of Azolla (A.microphylla and A. pinnata) exposed to man-made and natural stressors by evaluating biomass accumulation, pigments (chlorophyll a and b and carotenoid contents), photosynthetic activity and nitrogen metabolism. The study was carried out in field where two species of Azolla were cultured and treated with various concentrations (5, 10 and 20 μg ml(-1)) of herbicide; pretilachlor [2-chloro-2,6-diethyl-N-(2-propoxyethyl) acetanilide] and enhanced levels (UV-B1: ambient +2.2 kJ m(-2) day(-1) and UV-B2: ambient +4.4 kJ m(-2) day(-1)) of UV-B, alone as well as in combination. Biomass accumulation, photosynthetic pigments; chlorophyll a, b and carotenoids, photosynthetic oxygen yield and photosynthetic electron transport activities i.e. photosystem II (PS II) and photosystem I (PS I) in both the species declined with the increasing doses of pretilachlor and UV-B radiation, which further declined when applied in combination. The lower doses (5 and 10 μg ml(-1)) of pretilachlor and UV-B (UV-B1 and UV-B2) alone, damaged mainly the oxidation side of PS II, whereas higher dose (20 μg ml(-1)) of pretilachlor alone and in combination with UV-B1 and UV-B2 caused damage to PS II reaction centre and beyond this towards the reduction side. A significant enhancement in respiration was also noticed in fronds of both the Azolla species following pretilachlor and UV-B treatment, hence indicating strong damaging effect. The nitrate assimilating enzymes - nitrate reductase and nitrite reductase and ammonium assimilating enzymes - glutamine synthetase and glutamate synthase were also severely affected when treated either with pretilachlor and/or UV-B while glutamate dehydrogenase exhibited a stimulatory response. The study suggests that both the species of Azolla showed considerable damage under pretilachlor and UV-B treatments alone, however, in combination the effect was more intense. Further, in

  9. 青藏高原强UV-B辐射对美丽风毛菊光合作用和色素含量的影响%Effects of strong solar UV-B radiation on photosynthesis and photosynthetic pigment contents of Saussurea superba on Qinghai-Tibet Plateau

    Institute of Scientific and Technical Information of China (English)

    师生波; 尚艳霞; 朱鹏锦; 张德罡

    2011-01-01

    以青藏高原矮嵩草草甸的主要伴随种美丽风毛菊为材料,通过滤除太阳辐射光谱中UV-B成分的模拟试验,研究了强太阳UV-B辐射对高山植物光合作用、光合色素和紫外吸收物质的影响.结果表明:与对照相比,弱UV-B处理能促使美丽风毛菊叶片净光合速率增加和提高稳态PSⅡ光化学效率;对照中叶片厚度的相对增加能弥补单位叶面积光合色素的光氧化损失,是高山植物对强UV-B辐射的一种适应方式.短期滤除UV-B辐射处理时紫外吸收物质含量几乎没有变化,说明高山植物叶表皮层中该类物质受环境波动的影响较小.强UV-B环境下光合色素的相对增加是一种表象,而青藏高原强太阳UV-B辐射对高山植物美丽风毛菊的光合生理过程仍具有潜在的负影响.%Taking the main companion species Saussurea superba in an alpine Kobresia humilis meadow on Qinghai-Tibet Plateau as test material, a UV-B exclusion experiment with UV-B excluding and UV-B transmitting filters was performed to study the effects of strong solar UV-B on the photosynthesis, photosynthetic pigments, and UV-B-absorbing compounds of S. superba, aimed to examine the adaptation capability of alpine plants to strong solar UV-B radiation. The removal of UV-B components from natural sunlight increased the net photosynthetic rate (P<0. 05 ) and PS Ⅱ photochemistry efficiency of S. superba. The relatively increased leaf thickness under ambient UV-B could compensate the photo-oxidation of photosynthetic pigments, an inherent characteristic of alpine plants growing in intense UV-B. Short-term removal of UV-B radiation had no obvious effects on the UV-B-absorbing compounds, suggesting that these compounds in epidermal layer of S. superba could hardly be affected by the environment. It was concluded that the increase of photosynthetic pigment contents due to the enhancement of leaf thickness was a specious phenomenon, but the strong solar UV-B

  10. Temperature Sensitivity of Wheat Plant Respiration and Soil Respiration Influenced by Increased UV-B Radiation from Elongation to Flowering Periods%紫外(UV-B)辐射增强对拔节-孕穗期小麦植株呼吸和土壤呼吸的温度敏感性影响

    Institute of Scientific and Technical Information of China (English)

    陈书涛; 胡正华; 李涵茂; 季宇虹; 杨燕萍

    2009-01-01

    Field experiment was carried out in the spring of 2008 in order to investigate the effects of increased UV-B radiation on the temperature sensitivity of wheat plant respiration and soil respiration from elongation to flowering periods. Static chamber-gas chromatography method was used to measure ecosystem respiration and soil respiration under 20% UV-B radiation increase and control. Environmental factors such as temperature and moisture were also measured. Results indicated that supplemental UV-B radiation inhibited the ecosystem respiration and soil respiration from wheat elongation to flowering periods, and the inhibition effect was more obvious for soil respiration than for ecosystem respiration. Ecosystem respiration rates, on daily average, were 9%, 9%, 3%, 16% and 30% higher for control than for UV-B treatment for the five measurement days, while soil respiration rates were 99%, 93%, 106%, 38% and 10% higher for control than for UV-B treatment. The Q10 s (temperature sensitivity coefficients) for plant respiration under control and UV-B treatments were 1.79 and 1.59, respectively, while the Q10 s for soil respiration were 1.38 and 1.76, respectively. The Q10 s for ecosystem respiration were 1.65 and 1.63 under CK and UV-B treatments, respectively. Supplemental UV-B radiation caused a lower Q10 for plant respiration and a higher Q10 for soil respiration, although no significant effect of supplemental UV-B radiation on the Q10 for ecosystem respiration was found.%为研究紫外(UV-B)辐射增强对拔节-孕穗期麦田植株呼吸和土壤呼吸的温度敏感性的影响,应用静态箱-气相色谱法,于2008年春进行田间试验,观测UV-B辐射增强20%处理以及对照(CK)的麦田生态系统呼吸和土壤呼吸的日变化规律,同时观测温度、湿度等环境因子.结果表明,UV-B辐射增强明显抑制了拔节-孕穗期间麦田生态系统呼吸和土壤呼吸作用,且对土壤呼吸的抑制作用大于对生态系统呼吸的抑

  11. The Greenhouse effect: impacts of ultraviolet-B (UV-B) radiation, carbon dioxide (CO2), and ozone (O3) on vegetation.

    Science.gov (United States)

    Krupa, S V; Kickert, R N

    1989-01-01

    There is a fast growing and an extremely serious international scientific, public and political concern regarding man's influence on the global climate. The decrease in stratospheric ozone (O3) and the consequent possible increase in ultraviolet-B (UV-B) is a critical issue. In addition, tropospheric concentrations of 'greenhouse gases' such as carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) are increasing. These phenomena, coupled with man's use of chlorofluorocarbons (CFCs), chlorocarbons (CCs), and organo-bromines (OBs) are considered to result in the modification of the earth's O3 column and altered interactions between the stratosphere and the troposphere. A result of such interactions could be the global warming. As opposed to these processes, tropospheric O3 concentrations appear to be increasing in some parts of the world (e.g. North America). Such tropospheric increases in O3 and particulate matter may offset any predicted increases in UV-B at those locations. Presently most general circulation models (GCMs) used to predict climate change are one- or two-dimensional models. Application of satisfactory three-dimensional models is limited by the available computer power. Recent studies on radiative cloud forcing show that clouds may have an excess cooling effect to compensate for a doubling of global CO2 concentrations. There is a great deal of geographic patchiness or variability in climate. Use of global level average values fails to account for this variability. For example, in North America: 1. there may be a decrease in the stratospheric O3 column (1-3%); however, there appears to be an increase in tropospheric O3 concentrations (1-2%/year) to compensate up to 20-30% loss in the total O3 column; 2. there appears to be an increase in tropospheric CO2, N2O and CH4 at the rate of roughly 0.8%, 0.3% and 1-2%, respectively, per year; 3. there is a decrease in erythemal UV-B; and 4. there is a cooling of tropospheric air temperature due to

  12. The Greenhouse effect: impacts of ultraviolet-B (UV-B) radiation, carbon dioxide (CO2), and ozone (O3) on vegetation.

    Science.gov (United States)

    Krupa, S V; Kickert, R N

    1989-01-01

    There is a fast growing and an extremely serious international scientific, public and political concern regarding man's influence on the global climate. The decrease in stratospheric ozone (O3) and the consequent possible increase in ultraviolet-B (UV-B) is a critical issue. In addition, tropospheric concentrations of 'greenhouse gases' such as carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) are increasing. These phenomena, coupled with man's use of chlorofluorocarbons (CFCs), chlorocarbons (CCs), and organo-bromines (OBs) are considered to result in the modification of the earth's O3 column and altered interactions between the stratosphere and the troposphere. A result of such interactions could be the global warming. As opposed to these processes, tropospheric O3 concentrations appear to be increasing in some parts of the world (e.g. North America). Such tropospheric increases in O3 and particulate matter may offset any predicted increases in UV-B at those locations. Presently most general circulation models (GCMs) used to predict climate change are one- or two-dimensional models. Application of satisfactory three-dimensional models is limited by the available computer power. Recent studies on radiative cloud forcing show that clouds may have an excess cooling effect to compensate for a doubling of global CO2 concentrations. There is a great deal of geographic patchiness or variability in climate. Use of global level average values fails to account for this variability. For example, in North America: 1. there may be a decrease in the stratospheric O3 column (1-3%); however, there appears to be an increase in tropospheric O3 concentrations (1-2%/year) to compensate up to 20-30% loss in the total O3 column; 2. there appears to be an increase in tropospheric CO2, N2O and CH4 at the rate of roughly 0.8%, 0.3% and 1-2%, respectively, per year; 3. there is a decrease in erythemal UV-B; and 4. there is a cooling of tropospheric air temperature due to

  13. Quasi-biennial oscillation in atmospheric ozone, and its possible consequences for damaging UV-B radiation and for determination of long-term ozone trends

    Energy Technology Data Exchange (ETDEWEB)

    Gruzdev, A.N. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Atmospheric Physics

    1995-12-31

    The quasi-biennial oscillation (QBO) in ozone is supposed to be related to the QBO of zonal wind in the tropical stratosphere, with an approximate period of 29 months. Generally speaking, mechanisms of QBO-related effects in the extratropical atmosphere should depend on season and region, resulting in other periodicities (e.g., a 20-month periodicity) due to nonlinear interaction between the `pure` QBO and an annual cycle. Seasonal and regional dependences of QBO-related effects in ozone not only influence the regime of ozone variability itself, but can have important consequences, for example, for interannual changes in biologically active UV-B radiation and for determination of long-term ozone trends. This work is concerned with these problems

  14. 增补UV-B辐射下南亚热带森林建群树种叶片对UV-B辐射的防护%UV-B Screening in Leaves of Constructive Tree Species of Low Subtropical Forest under Supplementary UV-B Radiation

    Institute of Scientific and Technical Information of China (English)

    赵平; 孙谷畴; 曾小平

    2008-01-01

    研究了我国南亚热带森林5种建群树种UV-B辐射诱导的UV-B吸收物质(在280~320 nm波长下测定)的积累及抗UV-B辐射的可能性保护机制.增补UV-B辐射下,马尾松(Pinus massoniana)针叶的甲醇可溶性提取物和细胞壁的碱提取酚类的含量明显高于正常水平的光辐射下.红椎(Castanopsis hystrix)和厚壳桂(Cryptocarya chinensis)叶片的这些化学物质也升高,意味着增补UV-B辐射刺激UV-B辐射吸收物质的生成,形成抗UV-B辐射的功能性保护结构.然而,自然光下已含有大量细胞壁碱提取酚类的荷木(Schima superba)和藜蒴(Castanopsis fissa),这些化合物在增补UV-B辐射下则见下降,很有可能表皮层细胞壁碱提取酚类被转移到含有较低甲醇可溶性色素的液胞可溶性化合物里,这一现象意示着可能涉及叶肉组织光合机构的保护策略.增补UV-B下,马尾松针叶的叶绿素a和b含量不受影响,而其他4种阔叶树叶片则下降10.7% 到16.8%不等.胡萝卜素对增补UV-B辐射的响应变化不一,红椎和荷木的胡萝卜素水平下降,而马尾松、厚壳桂和藜蒴的胡萝卜素则上升,后者也许与功能性增加激发能耗散有关.结果显示,自然条件下不同树种展示出不同的驯化策略以形成抗UV-B辐射增加的防护机制.表4参29%The accumulation of UV-B absorbing materials (measured at the wavelength band of 280~320 nm) induced by UV-B radiation and possible involvement of a protective screening against UV-B radiation were investigated in five constructive species of low subtropical forest in South China. The methanol soluble extracts and alkali-extractable cell wall-bound phendics were significantly higher in needles of Pinus massoniana under supplementary UV-B radiation than under normal level of sunlight. These compounds were also enhanced in leaves of Castanopsis hystrix and Cryptocarya chinensis, implying that the supplementary UV-B radiation stimulated the synthesis

  15. Advances in influence of UV-B radiation on medicinal plant secondary metabolism%UV-B辐射对药用植物次生代谢的影响研究进展

    Institute of Scientific and Technical Information of China (English)

    吴洋; 房敏峰; 岳明; 柴永福; 王慧; 李易非

    2012-01-01

    Stratospheric ozone depletion results in an increased level of solar UV-B radiation (UV-B, 280-320 ran) reaching the earth surface. By the effect of UV-B radiation, various medicinal active ingredients changed because of the change of gene expression , enzyme activity and secondary metabolism, clinical effect is also changed. The research status of UV-B radiation and the accumulation of plant secondary metabolites in the past 10 years were summarized in this paper to supply reference for cultivation and exploitation of the medicinal plants.%平流层臭氧稀薄导致到达地面的中波紫外辐射( UV-B,280 ~ 320 nm)增加.受UV-B辐射影响,药用植物的基因表达、酶活性及次生代谢发生改变,导致多种药用活性成分含量变化从而影响临床疗效.该文综述了近10年来国内外学者对UV-B辐射与植物次生代谢产物积累方面的研究成果,为药用植物的栽培和开发提供参考.

  16. Antioxidant responses of damiana (Turnera diffusa Willd) to exposure to artificial ultraviolet (UV) radiation in an in vitro model; part ii; UV-B radiation.

    Science.gov (United States)

    Soriano-Melgar, Lluvia de Abril Alexandra; Alcaraz-Meléndez, Lilia; Méndez-Rodríguez, Lía C; Puente, María Esther; Rivera-Cabrera, Fernando; Zenteno-Savín, Tania

    2014-05-01

    Introducción: Los efectos de la radiación ultravioleta tipo B (UV-B) sobre las plantas medicinales se han investigado recientemente en el contexto del cambio climático, pero las modificaciones que genera la radiación UV-B podrían emplearse para modificar el contenido de compuestos antioxidantes, incluyendo los compuestos fenólicos. Objetivo: Generar información sobre el efecto de una alta exposición a UV-B artificial en el contenido antioxidante de damiana (Turnera diffusa, Willd) en un modelo in vitro. Método: Plántulas de damiana en cultivo de tejidos (medio Murashige-Skoog) fueron irradiadas con UV-B artificial en 3 diferentes dosis: (1) 0,5 ± 0,1 mW cm-2 (alto) por 2 h diarias, (2) 1 ± 0,1 mW cm-2 (severa) por 2 h diarias, o (3) 1 ± 0,1 mW cm-2 durante 4 horas diarias por 3 semanas. Se cuantificó la concentración de pigmentos fotosintéticos (clorofilas a y b, carotenoides), vitaminas (C y E) y compuestos fenólicos totales, la actividad enzimática de la superóxido dismutasa (SOD, EC 1.15.1.1) y las peroxidasas totales (POX, EC 1.11.1), así como la capacidad antioxidante total y la peroxidación de lípidos para evaluar el efecto de la alta radiación UV-B artificial en el contenido antioxidante de damiana in vitro. Resultados: Dosis altas y severas de radiación UV-B artificial modificaron el contenido antioxidante incrementando el contenido de vitamina C y disminuyendo el contenido de compuestos fenólicos totales, además de modificar el daño oxidativo de plantas de damiana en un modelo in vitro. Conclusión: La radiación UV-B modifica el contenido antioxidante en damiana en un modelo in vitro, dependiendo de la intensidad y el tiempo de exposición.

  17. 螺旋藻对短期增强UV-B辐射的生理生化响应%Physiological and biochemical responses of Spirulina platensis to short-term enhanced UV-B radiation

    Institute of Scientific and Technical Information of China (English)

    薛林贵; 石小霞; 褚可成; 陈志梅; 李师翁

    2011-01-01

    The amount of UV-B radiation reaching the earth's surface is increasing due to attenuation of the stratospheric ozone. Although the release of ozone-depleting material has declined significantly in the past decade, there is a considerable lag in the recovery of the ozone layer. Cyanobacteria are the oldest photosynthetic pro-karyotes and play an important role in the aquatic ecosystem. UV-B can penetrate water to a depth sufficient to disrupt aquatic ecosystems. For example, the depth of water required to remove 90% of the solar radiation at 310 nm is about 20 m in the clearest ocean. Thus, a large number of cyanobacteria populate aquatic habitats that are exposed to UV-B radiation. UV-B radiation is known to affect cyanobacteria biomass by disrupting physiological and biochemical processes. However, cyanobacteria have developed mechanisms to counteract the damaging effects of UV-B, including production of UV-screening pigments [(e.g., mycosporine-like amino acids (MAAs)] and downward migration. We evaluated the effects of short-term enhanced UV-B radiation on physiological indices, including photosynthetic pigment content, MDA, MAAs, and proline, in Spirulina platensis. S. Platensis were exposed to 240 μW/cm2UV-B for 3.5 h. By compared with untreated cyanobacteria cells, exposure to increased levels of UV-B radiation was associated with a reduction in chlorophyll a, carotenoid and phycobiliprotein content, with a change in MDA content. Our results suggest that increased levels of UV-B radiation causes bleaching of the photosynthetic pigment. Exposure to higher levels of UV-B was also associated with increased synthesis of MAAs and accumulation of proline. We hypothesize that this is a mitigation strategy to reduce the damaging effects of UV-B.%通过生物化学和对比分析的方法,研究了短期增强UV-B辐射对钝顶螺旋藻(Spirulina platensis)794光合色素、丙二醛(MDA)、类菌孢素氨基酸(MAAs)以及脯氨酸含量的影响.研究结果显

  18. Improving radiation data quality of USDA UV-B monitoring and research program and evaluating UV decomposition in DayCent and its ecological impacts

    Science.gov (United States)

    Chen, Maosi

    Solar radiation impacts many aspects of the Earth's atmosphere and biosphere. The total solar radiation impacts the atmospheric temperature profile and the Earth's surface radiative energy budget. The solar visible (VIS) radiation is the energy source of photosynthesis. The solar ultraviolet (UV) radiation impacts plant's physiology, microbial activities, and human and animal health. Recent studies found that solar UV significantly shifts the mass loss and nitrogen patterns of plant litter decomposition in semi-arid and arid ecosystems. The potential mechanisms include the production of labile materials from direct and indirect photolysis of complex organic matters, the facilitation of microbial decomposition with more labile materials, and the UV inhibition of microbes' population. However, the mechanisms behind UV decomposition and its ecological impacts are still uncertain. Accurate and reliable ground solar radiation measurements help us better retrieve the atmosphere composition, validate satellite radiation products, and simulate ecosystem processes. Incorporating the UV decomposition into the DayCent biogeochemical model helps to better understand long-term ecological impacts. Improving the accuracy of UV irradiance data is the goal of the first part of this research and examining the importance of UV radiation in the biogeochemical model DayCent is the goal of the second part of the work. Thus, although the dissertation is separated into two parts, accurate UV irradiance measurement links them in what follows. In part one of this work the accuracy and reliability of the current operational calibration method for the (UV-) Multi-Filter Rotating Shadowband Radiometer (MFRSR), which is used by the U.S. Department of Agriculture UV-B Monitoring and Research Program (UVMRP), is improved. The UVMRP has monitored solar radiation in the 14 narrowband UV and VIS spectral channels at 37 sites across U.S. since 1992. The improvements in the quality of the data result

  19. Effects of enhanced UV-B radiation on basic chemical compositions of two flue-cured tobacco cultivars%增强UV-B辐射对两个烤烟品种主要化学成分的影响

    Institute of Scientific and Technical Information of China (English)

    何承刚; 杨志新; 邵建平; 綦世飞; 周冀衡; 苏菲

    2012-01-01

    以云南两个烤烟主栽品种“云烟87”和“红花大金元”为试验材料,模拟昆明地区24.65%和39.53%的臭氧衰减时增强的UV-B辐射(分别为T1 5.30 kJ·m-2·d-1和T2 8.50 kJ·m-2·d-1),研究了大田条件下增强UV-B辐射对两个烤烟品种烟叶常规化学成分、质体色素和酚类含量的影响,为揭示UV-B辐射对烤烟化学质量特征的影响机理提供理论依据.结果表明:两种UV-B辐射明显降低了两个烤烟品种的水溶性糖和邻苯二酚含量,同时造成两个烤烟品种全氮、全钾、游离氨基酸、质体色素和类黄酮明显增加.增强UV-B辐射对两个烤烟品种烟碱含量的影响不同,增强UV-B辐射使“云烟87”的烟碱含量增加,使“红花大金元”烟碱含量降低.水溶性糖和总氮含量变化对UV-B辐射的响应说明“云烟87”品种对UV-B辐射更敏感.%The effects of enhanced UV-B radiation on basic chemical components, chromoplast pigment and phenols contents were studied in the leaves of two flue-cured tobacco cultivars - "Yunyan 87" (Y87) and "Honghuadajinyuan" (HD). Selected cultivars were exposed to UV-B radiation at ambient (control, CK), ambient plus 5.30 kJ·m -2·d-1 (T1) and ambient plus 8.50 kJ·m- 2·d-1(T2) levels that respectively simulated 24.65% and 39.53% ozone depletions under summer solstice field conditions in Kunming City (located at 25°04'N and 102°73'E). The study was meant to provide theoretical basis for the formation mechanism of chemical quality of flue-cured tobacco leaves in different ambient UV-B regions. Water soluble total sugar and catechol levels declined markedly in leaves of both cultivars with two doses of UV-B radiation compared with CK. However, total nitrogen, potassium, free amino acids, chromoplast pigment and flavonoid levels increased in leaves of both cultivars. While nicotine level increased in the leaves of Y87, it decreased in the leaves of HD under two doses of UV-B radiation compared with

  20. Study on the Effects of Enhanced UV-B Radiation and CO2 Doubling on Peanuts%UV原B辐射增强和CO2倍增复合作用对花生影响的研究

    Institute of Scientific and Technical Information of China (English)

    高晓玲; 何应森; 徐晓燕

    2013-01-01

    Under controlled conditions, the effects of enhanced UV-B radiation and CO2 doubling on peanuts seedlings are studied in this paper. The experimental results showed that after the composite treatment of enhanced UV-B radiation and CO2 doubling the peanut plant height, leaf number, leaf area and dry weight was significantly higher than the sepa-rate UV-B treatment group, close to or slightly higher than the control; experiments also showed that with the composite treatment the MDA content reduced and the enzyme activities of SOD, POD, CAT was significantly increased, lightly higher than the control. This indicated that the promoting effect of CO2 doubling on the peanut growth offset the harmful effects of UV-B radiation, enhancing the ability of anti UV-B radiation of peanut.%  通过控制条件下,研究增强的UV原B辐射和CO2倍增对花生幼苗的影响。实验结果表明,增强UV原B辐射和CO2倍增复合处理时,花生幼苗的株高、叶片数、叶面积及干重等明显高于单独UV原B处理组,接近或略高于对照组。实验还显示,复合处理能使MDA含量减少,SOD、POD、CAT酶活性明显升高,同样略高于对照组。说明CO2倍增对花生生长的促进作用抵消了UV原B辐射的伤害作用,增强了花生抗UV原B辐射的能力。

  1. Solar UV-B effects on PSII performance in Betula nana are influenced by PAR level and reduced by EDU

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Mikkelsen, Teis Nørgaard; Ro-Poulsen, Helge;

    2012-01-01

    -B transparent filter control (Teflon), UV-B-absorbing filter (Mylar) and UV-AB-absorbing filter (Lexan). Ethylenediurea (EDU), a chemical normally used to protect plants against ozone injury, was sprayed on the leaves both in the field and in an additional laboratory study to investigate if EDU mitigated......The long-term and diurnal responses of photosystem II (PSII) performance to near-ambient UV-B radiation were investigated in High Arctic Betula nana. We conducted an UV exclusion experiment with five replicated blocks consisting of open control (no filter), photosynthetic active radiation and UV...

  2. Appraisal of alternative skin model for the study of epidermal restoration following exposure to various environmental stress agents: ionising radiation and UV B

    International Nuclear Information System (INIS)

    Human skin is a major target tissue for ionising radiation (IR) and UV B. We developed a skin explant model and used 2 types of keratinocytes to study survival and oxidative stress induced by these radiations. We examined oxidative damages by measuring R.O.S. produced and cellular anti-oxidant defenses induced. We observed into skin exposed to IR a modulation of genes expression implied in the control of oxidative stress, confirmed by the decrease of catalase, glutathione peroxidase and superoxide dismutase enzymatic activities. The imbalance observed between anti- and pro-apoptotic genes expression shows that keratinocytes apoptosis may be partly dependent on radio-induced R.O.S. production. We showed the difference of radiosensitivity between N.H.E.K. and Ha Ca.T., which may be linked to their differential oxidative responses. In addition, during re-epithelialising, we demonstrated that activated N.H.E.K. after IR express keratin 6, release pro-inflammatory cytokines and proliferate, without modification of their differentiation. Treatment of N.H.E.K. with geranyl geranylacetone (G.G.A.) has a beneficial effect on their radio-induced activation by increasing IL-1 release, their migration in scrapped area and their survival. G.G.A. has an anti apoptotic ability (induction of Hsp70- caspase-3 pathway) and migratory properties (P38/RhoA activation) on N.H.E.K., but after IR, only caspase-3 pathway is induced. This work thus contributes to the understanding of cutaneous damages after IR and G.G.A. mechanism of action which accelerates re-epithelialising. (author)

  3. Effect of UV-B Radiation on POD and SOD Isoenzyme of Arabidopsis thaliana%UV-B辐射对拟南芥POD、SOD同工酶的影响

    Institute of Scientific and Technical Information of China (English)

    李晓阳; 孙永星; 宋丽平; 韩榕

    2011-01-01

    选择哥伦比亚生态型(Columbia-0)的野生型拟南芥(Arabidopsis thaliana L.)为供试材料,研究了其POD、SOD同工酶对不同剂量UV-B胁迫的响应.结果显示,POD和SOD同工酶活性与UV-B辐射的剂量关系密切.POD、SOD同工酶活性在低剂量UV-B辐射时呈增加趋势,在中、高剂量UV-B辐射时活性则呈下降趋势.在UV-B胁迫下,POD同工酶酶带没有发生变化;SOD同工酶酶带在胁迫下,出现了新的酶带(SOD4、SOD5).说明拟南芥在受到低剂量的UV-B胁迫下,可以通过提高自身的保护系统来抵御外界不良环境的影响;而受到较高剂量的UV-B胁迫时,会破坏植物的保护系统,造成不可逆的损伤.%Ecotype of Columbia ( Columbia-0) wild-type Arabidopsis (Arabidopsis thaliana L. ) was used to study the respond of UV-B stress of different doses on its POD and SOD isoenzyme. The results showed that, POD and SOD isoenzyme activity was very closed to the dose of UV-B radiation. The activity of POD and SOD isoenzyme showed an increasing trend in the low dose of UV-B radiation, but in the medium and high doses of UV-B radiation, the activity was decreased. In the stress of UV-B, the enzyme belts of POD isozymes did not change, and new belts of SOD isozymes ( SOD4, SODS ) was appeared. It was explained at low doses of UV-B stress, Arabidopsis could improve their own protection system to resist the adverse environmental impact from the outside world, but at high doses of UV-B stress, it would destroy the plant's protection system and cause irreversible damage.

  4. 低能氮离子束与UV-B增强对水稻光合及蒸腾速率的影响%Effects of low-energy N+ion beam irradiation on photosynthetic and transpiration in rice under enhanced UV-B radiation

    Institute of Scientific and Technical Information of China (English)

    李林玉; 黄群策; 张书艮; 赵帅鹏

    2013-01-01

    moderated the damage caused by enhanced UV-B radiation, while more ways should be found and applied in this field. Low-energy N+ion implantation has been widely used in the mutation breeding of plant and microorganism due to its higher mutation frequency and wide mutation spectrum since the early 1980s. There are some reports showing that appropriate doses of low-energy N+ion beam treatment could inspire the anti-oxidative enzyme system and change the physicochemical characteristics in plant cells on some level, which could regulate its defense system to deal with the outside stress. However, there was no report about the interactions between enhanced UV-B radiation and low-energy N+ion beam radiation on rice. The effects of low-energy N+ion beam irradiation on diurnal variations of photosynthesis and photosynthetic pigment contents in rice under enhanced UV-B radiation were investigated in the study. The experiment materials were pre-treated by three different doses of low-energy N+ ion beam that was conducted in Henan provincial at a key laboratory of ion beam bio-engineering, Zhengzhou university, China. Then the test materials were planted in an experimental field and uniformly managed routinely. One month later, the rice seedlings were implanted into the planting boxes provided by the laboratory. After turning green, the seedlings were treated with UV-B radiation for two months (from 8:00 to 17:00 per day) except for rainy or cloudy days. The dose of enhanced UV-B radiation was 16.46 kJ/m2·d (a 20% difference in ambient UV-B, Zhengzhou, China) which was detected by an ultraviolet irradiation detector and normalized at 297nm to obtain effective radiation. Two months later, the photosynthetic parameters (Pn,Tr,Gs,Ci) were determined with a portable photosynthesis system (CB-1102, Beijing Yaxin Liyi Science and Technology Co., Ltd. China) every two hours from 7:00 a.m. to 17:00 p.m. on a cloudless day, and the photosynthetic pigment content was determined too. The

  5. A thirty percent increase in UV-B has no impact on photosynthesis in well-watered and droughted pea plants in the field

    International Nuclear Information System (INIS)

    It has been suggested that field experiments which increase UV-B irradiation by a fixed amount irrespective of ambient light conditions (‘square-wave’), may overestimate the response of photosynthesis to UV-B irradiation. In this study, pea (Pisum sativum L.) plants were grown in the field and subjected to a modulated 30% increase in ambient UK summer UV-B radiation (weighted with an erythemal action spectrum) and a mild drought treatment. UV-A and ambient UV control treatments were also studied. There were no significant effects of the UV-B treatment on the in situ CO2 assimilation rate throughout the day or on the light-saturated steady-state photosynthesis. This was confirmed by an absence of UV-B effects on the major components contributing to CO2 assimilation; photosystem II electron transport, ribulose 1,5-bisphosphate regeneration, ribulose 1,5-bisphosphate carboxylase/oxygenase carboxylation, and stomatal conductance. In addition to the absence of an effect on photosynthetic activities, UV-B had no significant impact on plant biomass, leaf area or partitioning. UV-B exposure increased leaf flavonoid content. The UV-A treatment had no observable effect on photosynthesis or productivity. Mild drought resulted in reduced biomass, a change in partitioning away from shoots to roots whilst maintaining leaf area, but had no observable effect on photosynthetic competence. No UV-B and drought treatment interactions were observed on photosynthesis or plant biomass. In conclusion, a 30% increase in UV-B had no effects on photosynthetic performance or productivity in well-watered or droughted pea plants in the field. (author)

  6. Research advance on responsive and adaptive mechanism of Cryptogam to the increased UV-B radiation%隐花植物对UV-B辐射响应和适应机制的研究进展

    Institute of Scientific and Technical Information of China (English)

    回嵘; 李新荣; 贾荣亮; 赵昕; 刘立超

    2012-01-01

    Cryptogam means nonseed-bearing plant; it is a constituent part of biological soil crust ( BSC )-the main characteristic on the surface in arid and semi-arid regions, which plays a vital role in ecosystem. According to diversity and difference of the dominated species in BSC, the cryptogam is mainly distinguished into three basic types; algae, moss and lichen. Because of their simple morphological and anatomical structures, the cryptogam is easily influenced by environments and often used as an indicator of environmental variations. So the response and a-daptability of cryptogam to environmental factors is of great importance in the stability of the whole ecosystem. The increase in the intensity of ultraviolet radiation ( mainly UV - B) invades land due to stratospheric ozone depletion resulted from human activities, made a series of impacts on terrestrial beings, it also effects the composition, structure and function of cryptogam to an even greater degree. Many studies have shown that enhanced UV - B radiation intensity made effects on growth development, photosynthesis, metabolism, antioxidant system and cell membrane of plants. Therefore, studies related to the effects of enhanced UV - B radiation on cryptogam has become a growing tendency and one of the hot spots in UV - B radiation research. The Cryptogam has very important eco-value in arid and semi-arid regions, which is the dominant component of BSC in desert region, It is also one of the evaluating index for ecosystem stability and restoration of degraded ecosystem. Now there are many reports about the researches concerned with the effects of UV - B on cryptogam and as a result the paper introduces the concerned domestic and international researches in this field, which include effects of cryptogam to enhanced UV - B radiation on biomass, photosynthetic ability, photosynthetic pigments, antioxidant enzymes activity, water-soluble protein content, DNA damage, fatty acids and so on. In order to understand

  7. Outdoor studies on the effects of solar UV-B on bryophytes : Overview and methodology

    NARCIS (Netherlands)

    Boelen, P.; de Boer, M.K.; de Bakker, N.; Rozema, Jelte

    2006-01-01

    In this review all recent field studies on the effects of UV-B radiation on bryophytes are discussed. In most of the studies fluorescent UV-B tubes are used to expose the vegetation to enhanced levels of UV-B radiation to simulate stratospheric ozone depletion. Other studies use screens to filter th

  8. Effect of elevated ultraviolet-B (UV-B) radiation on CH4 emission in herbicide resistant transgenic rice from a paddy soil%UV-B辐射增强对抗除草剂转基因水稻CH4排放的影响

    Institute of Scientific and Technical Information of China (English)

    娄运生; 周文鳞

    2012-01-01

    to which transgenic biotechnology has been successfully applied for genetic improvements such as disease and/ or insect resistance, herbicide, drought and/or salt tolerance. However, transgenic rice has not yet been officially approved for commercial production in the world, because it is uncertain whether the rice will have any possible impacts on environmental and food safety. Therefore, safety assessment on transgenic rice was conducted to investigate gene flow through pollen transfer, change in biodiversity, non-target effects and food safety, etc. However, little attention has been paid to the effect of transgenic rice on CH4 emission in paddy soil. Hence, the objective of this study was to investigate the dynamics of CH4 emission in herbicide resistant transgenic rice from a paddy field under elevated UV-B radiation. Field experiment was conducted to investigate methane (CH4 ) emission as affected by elevated UV-B radiation. The field experiment was designed with two UV-B radiation levels, i. e. ambient (A, control) and elevated (E, 14.4 kj-m -d , simulating 25% stratospheric ozone depletion), and performed at the Station of Agricultural Meteorology, Nanjing University of Information Science and Technology, Nanjing, China. Two rice cultivars were tested in this experiment, including herbicide resistant transgenic rice (japonica line B2 ) and its parent conventional rice (japonica cv Xiushui 63 ) . The transgenic line of japonica rice B2 contained bar gene with herbicide Basta resistance. CH4 emission was determined by the closed chamber method at 10-day interval during rice growing period in a loamy clay paddy soil. The results indicated that, elevated UV-B radiation had no effect on seasonal dynamics of CH4 flux in paddy field. Compared with control, elevated UV-B radiation significantly increased CH4 flux and total amount of CH4 emission. The sub-total amount of CH4 emission peaked at tillering stage, and then jointing to booting stages, accounting for 51. 55

  9. Effects of UV-B radiation levels on concentrations of phytosterol, ergothioneine, and polyphenolic compounds in mushroom powder used as dietary supplements

    Science.gov (United States)

    Compositional changes of powder dietary supplement made from mushrooms previously exposed to different levels of UV-B irradiation were evaluated for the bioactive naturally occurring mushroom anti-oxidant, ergothioneine, other natural polyphenolic anti-oxidants: e.g. flavonoids, lignans, and others,...

  10. Effects of UV-B radiation on population growth of rotifer Brachionus urceus%UV-B辐射增强对壶状臂尾轮虫种群增殖的影响

    Institute of Scientific and Technical Information of China (English)

    王进河; 冯蕾; 唐学玺

    2009-01-01

    运用群体累计培养的方法研究了UV-B辐射增强对壶状臂尾轮虫(Brachionus urceus)种群增殖的影响.结果表明:UV-B辐射增强对壶状臂尾轮虫的种群数量、雌体抱卵率和种群增殖率都有显著影响(P<0.05).实验表明,在本实验辐射强度(20μW/cm2)和剂量范围内(0.24、0.48、0.72、0.96和1.20kJ/m2),壶状臂尾轮虫的种群数量和种群增殖率均以对照组最高,各UV-B辐射处理组则随UV-B辐射剂量的增大而呈一致性减小,说明该种群的种群数量和种群增殖率随UV-B辐射的增强显示一致性的影响,两者都可以作为大气UV-B辐射强弱的生物指标.%The effects of UV-B radiation on population growth of rotifer Brachionus urceus were studied using the method of population accumulative culture. The results showed that the population numbers, the percentage of egg-bearing females relative to the total number of females and population growth rate of rotifer Brachionus urceus were significantly affected by UV-B radiation (P<0.05). At the experimental intensity of 20μW/cm2and in the dose range studied (0.00, 0.24, 0.48, 0.72, 0.96 and 1.20kJ /m2), both the population number and growth rate was the highest in the control and decreased with the increment of UV-B radiation. In addition, the population number and growth rate of rotifer Brachionus urceus showed a similar tendency of decrease with the dose increase of UV-B radiation. Both of them could be used as an ideal biomarker for the enhancement of UV-B radiation.

  11. 大田条件下UV-B辐射对元阳梯田2个地方水稻品种硅、类黄酮和总酚含量的影响%Effects of UV-B Radiation on the Contents of Silicon, Flavonoids and Total Phenolic of Two Local Rice Varieties in Yuanyang Terrace Under Field Conditions

    Institute of Scientific and Technical Information of China (English)

    何永美; 湛方栋; 祖艳群; 陈海燕; 李元

    2013-01-01

    云南元阳梯田稻田被认为是持续稳定稻田生态系统的典型代表.在元阳梯田原生环境中,通过大田试验,研究UV-B辐射(0、2.5、5.0、7.5 kJ·m-2)增强对元阳梯田地方水稻白脚老粳和月亮谷的茎与叶硅含量、叶类黄酮和总酚含量的影响.结果表明:(1)UV-B辐射处理下,白脚老粳拔节期茎和叶的硅含量、月亮谷抽穗期茎的硅含量、拔节期和抽穗期叶的硅含量均显著增加.(2)UV-B辐射导致白脚老粳(除2.5 kJ·m-2)和月亮谷抽穗期叶的类黄酮含量显著增加.(3)UV-B辐射导致白脚老粳分蘖期(除2.5 kJ·m-2)、拔节期(除2.5 kJ ·m-2)和抽穗期叶的总酚含量均显著增加;月亮谷分蘖期和抽穗期(除2.5 kJ· m-2)叶的总酚含量显著增加.(4)2个水稻品种叶的硅含量与类黄酮、总酚含量均呈极显著正相关.总体来看,UV-B辐射增强促进白脚老粳茎与叶硅含量、叶类黄酮和总酚含量的增加,其增加百分率高于月亮谷,表明白脚老粳和月亮谷对UV-B辐射的抗性有所不同.%The local paddle field in Yuanyang Terrace was considered as a sustainable and stable agricultural ecosystem.Two local rice varieties,Baijiaolaojing and Yuelianggu,were grown in the paddy field for two consecutive years under ambient and supplemental levels of ultraviolet-B (UV-B,280~315 nm) radiation to determine the potential for alterations in contents of silicon in culm and leaves,of flavonoids and total phenolic in leaves.The supplemental UV-B radiation was 2.5 kJ· m-2,5.0 kJ·m-2 and 7.5 kJ· m-2,simulating a depletion of 10%,20% and 30% stratospheric ozone.The results showed that:(1)The silicon contents of culm and leaves in jointing stage of Baijiaolaojing,of culm in heading stage and of leaves in jointing and heading stage of Yuelianggu were siginificantly increased under UV-B radiation.(2)Except 2.5 kJ· m-2 UV-B radiation,the flavonoids contents of leaves in heading stage of Baijiaolaojing and

  12. Effect of Enhanced UV-B Radiation on Arabidopsis Mesophyll Cell Protein%增强UV-B辐射对拟南芥叶肉细胞蛋白的影响

    Institute of Scientific and Technical Information of China (English)

    魏小丽; 郑娜; 李晓阳; 韩榕

    2013-01-01

    Four-week-old wild-type Arabidopsis seedlings ( Columbia-O) was treated using different doses of UV-B radiation,the protein in the mesophyll cells was extracted using acetone precipitation and TCA-acetone,then Arabidopsis mesophyllcellular protein content and composition of the different intensity of UV-B radiation response were analyzed.The results showed that comparing two methods,the protein content of the TCA-acetone extract is relatively higher,which was more suitable for the analysis of enhanced UV-B radiation on Arabidopsis mesophyll cell protein; The changes of protein contents by two extraction methods showed the same trend,along with the increasing of UV-B radiation dose,the protein content increased first and then reduced,B2 group reached a maximum.In addition,the number of protein bands and expression has taken place significant change,the most obvious changes were also in the middle dose treatment group ( B2) ,both new bands and disappearance bands.This may be due to the Arabidopsis thaliana can activate some of its own resistance gene expressions and induce resistance protein by low doses of UV-B radiation,and thus resist the damage of UV-B; however,when subjected to high doses of UV-B radiation,damage their own protein synthesis pathway,and affect protein synthesis.%采用不同剂量的UV-B辐射处理4周龄的野生型拟南芥幼苗(Columbia-0),分别采用丙酮沉淀法和TCA-丙酮法提取其叶肉细胞中的蛋白质,进而研究分析拟南芥叶肉细胞中蛋白质的含量与组成对不同强度UV-B辐射的响应.结果显示,两种方法相比较,TCA-丙酮法所提取得到的蛋白含量相对较多,更适合于分析增强UV-B辐射对拟南芥叶肉细胞蛋白质的影响;而两种方法所提取得到的蛋白质含量的变化趋势相同,随着UV-B辐射剂量的增加,蛋白质含量呈先增加后减少的趋势,B2组达到了最大.此外,蛋白条带的数目和表达量也都发生了显著变化,同样

  13. 增强UV—B辐射下NO对细胞壁多糖组分含量的影响%Effects of NO on Contents of Cell Wall Polysaccharides Fraction under Enhanced UV-B Radiation

    Institute of Scientific and Technical Information of China (English)

    曲颖; 王弋博; 金文杰; 李文建; 安黎哲

    2012-01-01

    以豌豆(Pisumsativum)幼苗茎为材料,研究增强UV—B辐射下一氧化氮(N0)对细胞壁多糖组分含量的影响。结果表明,增强UV-B辐射使单位长度内细胞壁多糖总量增加;使细胞壁多糖结构组分果胶、半纤维素I、半纤维素Ⅱ和纤维素的含量增加;NO供体处理对半纤维素I、半纤维素Ⅱ和纤维素的影响与UV-B辐射相似,使它们含量增加;增强UV-B辐射条件下,氮合酶(NOS)抑制剂和NO清除剂处理使半纤维素I、半纤维素Ⅱ和纤维素的含量降低,抵消了增强UV-B辐射对他们的影响。说明UV-B辐射可能通过N0信号上调了半纤维素I、半纤维素Ⅱ和纤维素含量,增加了他们在细胞壁多糖中的比例,因而改变细胞壁的化学特性以及影响了细胞壁的机械延展性。无论对照条件下用N0供体处理,还是UV—B辐射条件下用NOS抑制剂、N0清除剂处理,对果胶含量影响不大,表明N0信号可能与UV-B辐射诱导果胶含量增加无关。%Effects of nitric oxide (NO) on contents of cell wall polysaccharides fraction in stems of pea (Pi- sum sativum)seedlings under enhanced UV-B radiation were studied. Results showed that total contents of cell wall polysaccharides, and contents of pectin, hemicellulose I, hemicellulose II and celluloses at pea seedling stems per unit length increased under UV-B radiation. NO donor treatment also increased contents of hemicellulose I, hemicellulose II and celluloses at pea seedling stems per unit length. Under UV-B radia- tion treatments, the additional inhibitor of nitric oxide synthase and NO scavenger abated the effects of UV- B radiation on contents of hemicellulose I, hemicellulose II and celluloses, making their contents decreased. It is believed that UV-B radiation, with NO as a probable signaling molecule, can increase the contents of hemicellulose I, hemicellulose II and celluloses. So their proportions among cell wall

  14. UV-B and Mediterranean forest species: Direct effects and ecological consequences

    Energy Technology Data Exchange (ETDEWEB)

    Paoletti, E. [Istituto Protezione Piante, Consiglio Nazionale delle Ricerche, Via Madonna del Piano, I-50019 Sesto Fiorentino (Italy)]. E-mail: e.paoletti@ipp.cnr.it

    2005-10-15

    Experimental results from plants receiving elevated doses of UV-B radiation generally show that Mediterranean forest species are well protected against increases in UV-B radiation. Natural adaptations to water stress and excess light (elevated concentrations of UV-B screening compounds, leaf hairs, thick cuticle and epidermis), and UV-B responses (thickening of the cuticle, increase in carotenoids) may avoid or counter-balance UV-B radiation damage. This response confirms that Mediterranean forest vegetation is adapted to face oxidative stress factors, such as elevated tropospheric ozone concentrations, drought and high radiation, including UV-B. Nevertheless, in the long term, species-specific and season-specific differential responses in growth, physiology, phenology and reproductive behaviour may alter the interactions between species and lead to slow but important changes in ecosystem structure and function. - Mediterranean plant adaptations against water stress and excess light may also afford protection against UV-B.

  15. UV-B and Mediterranean forest species: Direct effects and ecological consequences

    International Nuclear Information System (INIS)

    Experimental results from plants receiving elevated doses of UV-B radiation generally show that Mediterranean forest species are well protected against increases in UV-B radiation. Natural adaptations to water stress and excess light (elevated concentrations of UV-B screening compounds, leaf hairs, thick cuticle and epidermis), and UV-B responses (thickening of the cuticle, increase in carotenoids) may avoid or counter-balance UV-B radiation damage. This response confirms that Mediterranean forest vegetation is adapted to face oxidative stress factors, such as elevated tropospheric ozone concentrations, drought and high radiation, including UV-B. Nevertheless, in the long term, species-specific and season-specific differential responses in growth, physiology, phenology and reproductive behaviour may alter the interactions between species and lead to slow but important changes in ecosystem structure and function. - Mediterranean plant adaptations against water stress and excess light may also afford protection against UV-B

  16. Growth, photosynthesis and nitrogen metabolism in soybean varieties after exclusion of the UV-B and UV-A/B components of solar radiation

    Institute of Scientific and Technical Information of China (English)

    Sanjay; Singh; Baroniya; Sunita; Kataria; Govind; Prakash; Pandey; Kadur; N.; Guruprasad

    2014-01-01

    A field experiment was conducted to study the impact of the exclusion of the solar UV components on growth, photosynthesis and nitrogen metabolism in soybean(Glycine max)varieties PK-472, Pusa-24, JS 71-05, JS-335, NRC-7 and Kalitur. The plants were grown in specially designed UV exclusion chambers wrapped with filters to exclude UV-B or UV-A/B and transmitted all UV. Exclusion of UV significantly enhanced the growth of the aerial parts as well as the growth of the below ground parts in all of the six soybean varieties.Nitrate reductase activity(NRA) was significantly reduced, whereas leghemoglobin(Lb)content, total soluble protein, net photosynthesis(Pn) and α-tocopherol content were enhanced after UV exclusion. The exclusion of solar UV-A/B enhanced all parameters to a larger extent than the exclusion of solar UV-B in four of the six varieties of soybean except for NRC-7 and Kalitur. These two varieties responded more to UV-B exclusion compared to UV-A/B exclusion. A significant inverse correlation between the NRA and the number of nodules per plant was observed. The extent of response in all parameters was greater in PK-472 and JS71-05 than that in Kalitur and JS-335 after UV exclusion. The exclusion of UV augmented the growth of nodules, Lb content and α-tocopherol levels and conferred higher rates of Pnto support better growth of nodules. Control plants(+ UV-A/B) seemed to fulfill their N demand through the assimilation of NO-3resulting in lower symbiotic nitrogen fixation and higher NR activity.

  17. Growth, photosynthesis and nitrogen metabolism in soybean varieties after exclusion of the UV-B and UV-A/B components of solar radiation

    Directory of Open Access Journals (Sweden)

    Sanjay Singh Baroniya

    2014-12-01

    Full Text Available A field experiment was conducted to study the impact of the exclusion of the solar UV components on growth, photosynthesis and nitrogen metabolism in soybean (Glycine max varieties PK-472, Pusa-24, JS 71-05, JS-335, NRC-7 and Kalitur. The plants were grown in specially designed UV exclusion chambers wrapped with filters to exclude UV-B or UV-A/B and transmitted all UV. Exclusion of UV significantly enhanced the growth of the aerial parts as well as the growth of the below ground parts in all of the six soybean varieties. Nitrate reductase activity (NRA was significantly reduced, whereas leghemoglobin (Lb content, total soluble protein, net photosynthesis (Pn and α-tocopherol content were enhanced after UV exclusion. The exclusion of solar UV-A/B enhanced all parameters to a larger extent than the exclusion of solar UV-B in four of the six varieties of soybean except for NRC-7 and Kalitur. These two varieties responded more to UV-B exclusion compared to UV-A/B exclusion. A significant inverse correlation between the NRA and the number of nodules per plant was observed. The extent of response in all parameters was greater in PK-472 and JS71-05 than that in Kalitur and JS-335 after UV exclusion. The exclusion of UV augmented the growth of nodules, Lb content and α-tocopherol levels and conferred higher rates of Pn to support better growth of nodules. Control plants (+ UV-A/B seemed to fulfill their N demand through the assimilation of NO3− resulting in lower symbiotic nitrogen fixation and higher NR activity.

  18. 达乌里胡枝子抗氧化防御系统对增强UV-B辐射的动态响应%Responses of Antioxidant Defense System of Lespedeza davurica to Enhanced UV-B Radiation

    Institute of Scientific and Technical Information of China (English)

    郝文芳; 杜润峰; 王龙飞

    2012-01-01

    为探究增强UV-B辐射对达乌里胡枝子(Lespedeza davrica)抗氧化能力的影响,采用盆栽试验研究其在不同UV-B辐射强度(CK=0,T1=1.944 kJ· m-2 ·d-1,T2=3.002 kJ·m-2·d-1)下的抗氧化保护系统相关指标的动态响应,UV-B辐射处理持续15 d,每3d取样一次至结束后第3d再取样一次.结果表明:随着处理时间的延长,增强UV-B辐射使超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性降低,抗坏血酸过氧化物酶(APX)和过氧化物酶(POD)活性升高,且SOD,POD和CAT的活性随着辐射强度的增加而降低,APX活性在开始处理9d内随着辐射强度的增加而增加,此后随着辐射强度的增加而降低;增强UV-B辐射使抗坏血酸(AsA)含量增加,类胡萝卜素(Car)含量降低,且二者的含量均随着辐射强度的增加而降低;增强UV-B辐射使超氧阴离子(Oi-)、丙二醛(MDA)含量升高,O2·-含量和MDA含量均随着辐射强度的增加而增加.UV-B处理结束后,除SOD活性、POD活性、AsA含量呈下降趋势外,其他指标都呈上升趋势.通过隶属函数法综合评价得出:增强UV-B辐射降低了达乌里胡枝子的抗氧化能力,随着UV-B辐射强度的增加,抗氧化能力降低.%The objective of this study was to investigate the effects of different UV-B radiation intensity (CK, T1. T2)on antioxidant defense system and other related indicators of Lespedeza davurica (Laxm. ) Schindl. Malonaldehyde (MDA), ascorbic acid (AsA) and carotenoid (Car) contents, as well as superox-ide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) activities of leaves from Lespedeza davurica under different UV-B radiation intensity were investigated. Samples were collected once every three days. The UV-B treatment was continued 15 days. Result indicated that SOD and POD activities decreased, APX and POD activities increased with UV-B radiation enhanced during the whole treatment time. SOD, POD and CAT activities decreased with UV-B

  19. Effects of Enhanced UV-B Radiation on Accumulation and Cycling of Mg and Zn of Wheat Field Ecosystem.%增强的UV-B辐射对麦田生态系统Mg和Zn累积和循环的影响

    Institute of Scientific and Technical Information of China (English)

    李元; 王勋陵; 胡之德

    2001-01-01

    Influences of enhanced ultraviolet radiation (UV-B,280-315nm) on accumulation and cycling of Mg and Zn of wheat field ecosystem were investigated under field conditions.UV-B radiation increased concentrations of Mg and Zn in leaves and stems,and affected concentrations of Mg and Zn in roots and spikes at various developmental stages significantly.The responses of accumulation of Mg and Zn in leaves to UV-B radiation were different among developmental stages.Accumulation of Zn in stems were higher than control under 2.54 and 4.25 kJ.m-2 UV-B radiation,and lower than control under 5.31 kJ.m-2 UV-B radiation.At various developmental stages,UV-B radiation significantly reduced accumulation of Mg in stems,roots and spikes,and accumulation of Zn in roots and spikes.UV-B radiation significantly decreased accumulation of Mg and Zn in whole plants at various developmental stages.The contribution of biomass to the accumulation of Mg and Zn might be more than that of the concentrations of Mg and Zn.UV-B radiation reduced output of Mg and Zn of spring wheat colonies.This might indicate decreases in output-input ratio and cycling function of Mg and Zn in wheat field ecosystem.Increases in concentrations of exchangeable Mg and available Zn in soil were the results of decreases in output of Mg and Zn of spring wheat colonies. It might lead to the occurrence of higher storage of Mg and Zn in soil.

  20. Effects of anthracene and UV-B radiation on larvae of Argopecten irradians%蒽和UV-B辐射增强对海湾扇贝早期发育的影响

    Institute of Scientific and Technical Information of China (English)

    谭海丽; 王玉堃; 唐学玺; 周斌; 王其翔; 王悠

    2013-01-01

    The effects of anthracene and UV-B radiation on the early stage embryos development of benthos, and the single and joint a-cute toxicological effects of anthracene and UV-B radiation on the trochophore and D larvae of Argopecten irradians under the controlled laboratory conditions were studied. The results showed that with the increase of time and the anthracenes concentration or the increase of days and radiation does, the liabilities of the trochophore and D larvae declined. With the combination of anthracene and UV-B radiation , the liabilities of trochophore and D larvae were lower than those in the single action. Compared to D larvae, the trochophore was more sensitive to anthracene and UV-B radiation.%为了探讨蒽和UV-B辐射对底栖生物早期发育的影响,在实验生态学的条件下,选择海湾扇贝(Argopecten irradians)担轮幼虫和D型幼虫作为受试生物进行单一和联合急性毒性试验.结果表明:在实验的蒽浓度和UV-B辐射剂量下,随着蒽浓度和作用时间的增加,海湾扇贝担轮幼虫和D型幼虫的存活率逐渐降低;随着UV-B辐射剂量和辐射天数的增加,海湾扇贝担轮幼虫和D型幼虫存活率下降;在蒽和UV-B辐射共同作用对担轮幼虫和D型幼虫处理时,其两个发育阶段的存活率较两者单独作用的存活率均低很多;担轮幼虫较D型幼虫对蒽和UV-B辐射更敏感.

  1. Effect of Enhanced UV-B Radiation on Stress Physiology of Mentha piperita L.%增强UV-B辐射对胡椒薄荷逆境生理指标的影响

    Institute of Scientific and Technical Information of China (English)

    吴能表; 马红群

    2012-01-01

    The stress physiology of Mentha piperita L.under enhanced UV-B radiation(natural light conrol 0、light UV-B radiation stress 0.15 W/m^2 and heavy UV-B radiation stress 0.35 W/m^2) was studied.The result indicated that Mentha piperita L.made adaptation physiological reaction under enhanced UV-B radiation.The content of proline,soluble sugar and three antioxidases increased while the content of soluble protein decresed under 0.15 W/m^2 UV-B radiation.The content of proline and CAT activity rose firstly,then went down later;the content of soluble sugar and SOD activity rose firstly then stabilized;while the content of soluble protein,MDA and POD activity went down firstly then rose.Though the variation of all the indexs was different under enhanced UV-B radiation,all the indexs except the content of soluble protein were increased compareing to themselves under natual light control.%对增强UV-B辐射胁迫下(辐射强度分别为自然光对照0、0.15 W/m^2、0.35 W/m^2)下生长的胡椒薄荷(Mentha piperita L.)逆境生理指标的动态变化进行了研究.结果表明:薄荷对增强UV-B辐射胁迫做出了适应性生理反应.0.15 W/m^2下薄荷叶片内脯氨酸、可溶性糖、MDA质量浓度及3种抗氧化酶活性升高,蛋白质质量浓度下降;0.35 W/m^2下薄荷叶片内脯氨酸质量浓度和CAT活性先升高后降低,可溶性糖质量浓度和SOD活性先升高再趋于平稳,可溶性蛋白质、MDA质量浓度和POD活性先降低后升高.尽管不同强度UV-B辐射下各个指标变化趋势不同,但与自然光对照相比,经过UV-B辐射处理后,薄荷内可溶性蛋白质质量浓度降低,而其它指标均升高.

  2. Effect of Enhanced UV-B Radiation on the Contents of Aroma Precursor of Flue-cured Tobacco%增强UV-B辐射对烤烟香气前体物含量的影响

    Institute of Scientific and Technical Information of China (English)

    左敏; 周冀衡; 何伟; 肖志新; 杨虹琦; 张发明; 柳立; 彭艳; 陈习宇

    2011-01-01

    为探讨不同UV-B辐射强度对烤烟品种不同部位烟叶香气前体物含量的影响,本研究以红大和K326为材料,分析了增加UV-B辐射强度后对两个烤烟品种烟叶的叶绿素、类胡萝卜素、多酚类物质和主要非挥发性有机酸、高级脂肪酸等香气前体物含量的影响.结果表明:增强UV-B辐射,两个烤烟品种烟叶的叶绿素、类胡萝卜素、多酚类物质和部分多元酸、高级脂肪酸等香气前体物含量明显提高,且1.75 W/m2 UV-B辐射处理烟株的香气前体物增幅大于4.55 W/m2 UV-B辐射处理.同时,增加UV-B辐射对不同部位烟叶香气前体物含量的影响也不尽相同,其中部烟叶受到的影响明显高于下部烟叶;而红大品种在增大UV-B辐射处理后,其香气前体物含量的增幅明显高于K326品种.%A pot experiment was carried out to explore the effect of different UV-B radiation intensity on the contents of aroma precursor of different leaves of flue-cured tobacco. The contents of chlorophyll , carotenoids, polyphenols and main non-volatile acids, fatty acids were analyzed after enhancing UV-B radiation. The results showed that the contents of chlorophyll, carotenoids, polyphenols and part of multiple acids, higher fatty acid increased obviously. And the increasing rates of the contents of aroma precursors of tobacco under 1. 75 W/m2 UV-B radiation were more than that of the tobacco under 4. 55 W/m2 UV-B radiation. In the meantime, enhanced UV-B radiation didn't have the same effect on the contents of aroma precursor of different leaves of flue-cured tobacco. The effect on middle leaves was stronger than that of bottom leaves. And the increasing rates of the contents of aroma precursors of hongda were more than that of K326 obviously after enhancing UV-B radiation.

  3. 基于光子技术的UV-B辐射对植物细胞伤害评价方法%Evaluation Method of UV-B Radiation Damage on Plant Cell Based on Photonic Technology

    Institute of Scientific and Technical Information of China (English)

    习岗; 张晓辉; 刘锴; 李少华

    2011-01-01

    用50 μW/cm2 UV-B连续辐射大豆愈伤组织16 h,发现大豆愈伤组织的自发发光强度逐渐增长,延迟发光呈现衰减的趋势.通过对延迟发光动力学过程的分析,得到了UV-B辐射下大豆愈伤组织延迟发光的特征参数积分强度I(T)、初始光子数I0、相干时间τ和衰减参数β的变化规律.结果表明,大豆愈伤组织延迟发光初始光子数I0、相干时间τ和衰减参数β随着UV-B辐射时间的延长逐渐减小,延迟发光积分强度I(T)与初始光子数I0成极好的正相关.根据生物超弱光子辐射的意义定义了描述细胞生命状态有序程度的序参量,发现在50 μW/cm2UV-B连续辐射下,大豆愈伤组织序参量逐渐减小,大豆愈伤组织序参量的变化很好地反映了UV-B辐射对组织细胞的伤害.%In order to evaluate the method of UV-B radiation damage on plant cell by photonic technology,soybean callus was radiated by 50 μW/cm2 UV-B for 16 h. Ultraweak photon emission from soybean callus was collected and analyzed. The results showed that strength of spontaneous luminescence (SL) in ultraweak photon emission of soybean callus increased and delayed luminescence (DL) decreased gradually. Through the analyses of dynamic presses of DL, the change rules of dynamic parameters of DL such as integrated intensity I( T), initial I0, correlation time τ and decay constantβ were obtained. It was indicated that integrated intensity I( T), initial photon number I0, correlation time τ and decay constant β decreased with the UV-B radiation time, and I(T) was positive correlation to initial photon number I0. The order parameter used to describe order degree of cell was defined according to biological signification of ultraweak photon emission. The study found that the changes of the order parameter of soybean callus under the action of UV-B radiation reflected the damage of UV-B radiation on cell. So, the damage of UV-B radiation on plant cell could be expressed by

  4. Ultraviolet radiation levels associated with the use of fluorescent general lighting, UV-A and UV-B lamps in the workplace and home

    International Nuclear Information System (INIS)

    A detailed programme of measurements was undertaken by NRPB to determine the ultraviolet irradiance levels likely to be encountered in the workplace and in the home, where fluorescent lighting is used. Assessments have been made of the possible potential risk of the induction of acute effects (photokeratitis, erythema) and of inducing malignant melanoma and non-malignant melanoma skin cancers resulting from exposure to commonly used fluorescent lamps. The optical absorption properties of materials commonly used in diffusers and controllers in commercial and domestic lighting units were also measured. Irradiance data, both weighted (for biological effectiveness) and unweighted, for various lamp types are presented in the report, together with some typical spectral output distributions. The results show that at commonly used illumination levels the UVR emissions from general and special fluorescent lamps presented neither an acute nor a significant chronic hazard. High UV-B emission levels were measured from 'UV-B' lamps used in this study, and exposure to these lamps would result in acute injury within a short time. Great care should be taken in the use of these lamps, and advice should be provided to workers to ensure safe working conditions and procedures. (author)

  5. Effect of UV-B radiation on Reactive Oxygen Species and Antioxidant Enzymes of Nostoc flagelliforme Cells%UV-B辐射对发菜细胞活性氧及抗氧化酶活性的影响

    Institute of Scientific and Technical Information of China (English)

    撒玉霞; 于海峰; 杨蕾

    2013-01-01

    In order to explore the impact of ultraviolet-B (UV-B) radiation on reactive oxygen species (ROS) metabolism, the changes of reactive oxygen species(ROS) content and antioxidant enzyme activities were determined in liquid suspension cultivation of Nostoc flagelliforme cells. The results indicated that the superoxide anion (O2-) production and hydrogen peroxide (H2O2) content of Nostoc flagelliforme cells were increased under 1 and 5 W/m2 UV-B treatment, and the maximum of O2- production reached under UV-B treatment for 6 h, that were 480.62 and 510.34 nmol/g DW, respectively. The H2O2 content was increased at all times and reached 210.24 and 229.89 nmol/g DW under UV-B treatment for 48 h .The malondialdehyde (MDA) content attained 0.085 and 0.147 μmol/g DW .which were 251.70% and 413.72% of the control exposure to UV-B for 48 h . The activities of superoxide dismutase (SOD) and catalase (CAT) reached the maximum at 12 h at both intensities. The ascorbate peroxidase (APX) activity was increased in the early radiation ( 0~6 h ), then APX activity was unstable under 1 W/m2 UV-B treatment and declined rapidly under 5 W/m2 UV-B treatment%以液体悬浮培养的发菜细胞为研究对象,测定UV-B辐射处理后发菜细胞中活性氧含量和抗氧化酶活性的变化,探讨UV-B辐射对发菜细胞活性氧代谢的影响.实验结果表明,在1 W/m2和5 W/m2 UV-B辐射下,处理时间延长,发菜细胞中的超氧阴离子(O2-)与过氧化氢(H2O2)的含量显著增加,O2-的含量在辐射处理6h时达到最大值480.62、510.34 nmol/g DW,分别为对照的160.09%和169.99%,H2O2的含量是持续增加,在48h达到210.24和229.89 nmol/g DW.丙二醛(MDA)含量在48 h时达到0.085和0.147μmol/gDW,分别为对照的251.70%和413.72%.超氧化物歧化酶(SOD)和过氧化氢酶(CAT)的活性先升高后降低,在辐射12h时均达到最大;抗坏血酸过氧化物酶(APX)的活性在辐射初期(0~6 h)呈增长趋势,随后经1W/m2 UV-B辐射

  6. 增强UV-B辐射对3种芦荟蒽醌类物质含量的影响%Effects of Enhanced UV-B Radiation on Anthraquinones Content of 3 Species of Aloe

    Institute of Scientific and Technical Information of China (English)

    王红星; 胡春红; 李景原

    2011-01-01

    以中华芦荟、库拉索芦荟和木立芦荟为试验材料,采用HPLC技术,研究了增强UV-B辐射对3种芦荟叶片中主要药用成分总蒽醌、芦荟素和芦荟大黄素含量的影响.结果显示:增强UV-B辐射20 d,每天处理6 h,库拉索芦荟和木立芦荟叶中总蒽醌、芦荟素、芦荟大黄素的含量增加,叶提取物中出峰数量增多,总峰面积增大;而中华芦荟中蒽醌类物质含量显著降低,叶提取物中出峰数量减少,总峰面积减少.研究表明,增强UV-B辐射能刺激库拉索芦荟和木立芦荟叶片中蒽醌类物质的积累和新物质的合成,而不利于中华芦荟蒽醌类物质的积累.%Effects of enhanced UV-B radiation on anthraquinones,aloin and aloe-emondin contents of 3 species of Aloe were studied by High Performance Liquid Chromatography(HPLC).The results indicated that twenty days of enhanced UV-B radiation (daily 6 h) could increase total anthraquinone,aloin,aloe-emodin contents in Aloe barbadensis and Aloe arborescens leaves.In addition,the number of peaks,the total peak area increased in A.barbadensis and A.arborescens leaf extracts.However, the total anthraquinone, aloin,aloe-emodin contents, the number of peaks,the total peak area lowered significantly under the UV-B radiation in Aloe vera var.chinensis.This result shows that the accumulation of anthraquinone in A.barbadensis and A.arborescens leaves can be promoted by UV-B radiation but not conducive to A.vera var.chinensis.

  7. 黄连同工酶及相关逆境指标对UV-B的响应研究%Response of Isozyme and Stress Indexes of Coptis chinensis to UV-B Radiation

    Institute of Scientific and Technical Information of China (English)

    温泉; 张楠; 曹瑞霞; 周心渝; 唐娟; 吴能表

    2012-01-01

    Objective:To study the physiological mechanism of anti-stress of Coptic chinensis and provide theoretical basis for its cultivation and promoting its quality. Methods: Different degrees of the range of time and intensity of UV-B radiation were set in the experiment. Used the technique of polyacrylarnide gelatin vertical board electrophoresis(PAGE) to analyse the isozyme and related stress index. Results:The isoenzymic bands of SOD1 (Rf = 0. 125),SOD2(Rf = 0.312),CAT1(Rf = 0.428),POD3(Rf = 0.290),POD4(Rf = 0.636) were induced by UV-B radiation after 3 hours, with the increase of the lime of UV-B radiation, those isoenzymic bands was going to vanish or became unclear. Moreover,isoenzymic bands of CAT1 (Rf = 0.428) 、POD3( Rf=0. 290) disappeared in advance under heavy intensity of UV-B radiation. Furthermore, the contents of MDA, soluble sugar, proline were higher dramatically than those of control group under UV-B radiation. However,excluding the increases of proline in UL group,the content of MDA,soluble sugar,proline of other groups commenced to decrease slowly and isoenzymic bands of soluble protein increase after 7 hours of UV-B radiation. Conclusion; The increase of the expression of antioxidase isozyme, accumulation of soluble sugar ,soluble protein and oilier antioxidase matter is induced by the short-time UV-B radiation, which can protect Coplis chinensis from being harmed by UV-B radiation. However,regulation system of Coptis chinensis are broken,metabolism is disordered,the bands of antioxidase isozyme vanish or weaken, the bands of soluble protein are increased and widened,these phenomenon is caused by 7 hours of UV-B radiation.%目的:探讨UV-B辐射胁迫下黄连的抗逆生理机制,为黄连栽培及提高黄连品质提供参考依据.方法:通过设置UV-B辐射时间及不同强度梯度,运用聚丙烯酰胺垂直板电泳技术,对各处理组的黄连同工酶及相关逆境指标进行了分析.结果:UV-B辐射3h后,SOD1(Rf=0.125)、SOD2(Rf

  8. 金龟子绿僵菌分生孢子暴露在B段紫外光下毒力的降低%Exposure of Metarhizium anisopliae conidia to UV-B radiation reduces its virulence

    Institute of Scientific and Technical Information of China (English)

    Edimara A Francisco; Drauzio E N Rangel; Newton La Scala Jr; José C Barbosa; Ant(o)nia do C B Correia

    2008-01-01

    The UV-A and UV-B wavelengths of solar radiation may seriously reduce viability of Metarhizium anisopliaeconidia,a fungus used extensively in Brazil for insect pest control. The conidial tolerances to UV-A and UV-B radiation werestudied for one isolate (IBCB 425) commercially available product produced on rice grains. Aqueous or oil emulsion conidialsuspensions were irradiated for O (control), 2, or 3 h using the solar simulator filtered with diacetate filter to remove UV-Cradiation which afforded 652 mW.m-2 in the spectral range of 280~370 nm. The UV tolerance was based on conidial germi-nation (viability) and virulence to Diatraea saccharalis larvae. Conidia formulated with oil emulsion had higher survival after3 h of UV exposure, but the virulence of the eonidia previously exposed to 2 h of UV radiation were similar when oil formula-ted or not. The mortality of D. saccharalis caterpillars exposed to non-UV-irradiated conidia was greater than that of larvae ex-posed to irradiated conidia, and the LT50values were lower for the non-irradiated suspensions than for those irradiated. Thisapparent reduction in virulence was directly related reduction in viability or delay of germination of UV-irradiated conidia.

  9. Ultraviolet radiation levels associated with the use of fluorescent general lighting, UV-A and UV-B lamps in the workplace and home

    CERN Document Server

    Whillock, M; MacKinlay, Alistair F; Mundy, S J; Todd, Carl David

    1988-01-01

    A detailed programme of measurements was undertaken by NRPB to determine the ultraviolet irradiance levels likely to be encountered in the workplace and in the home, where fluorescent lighting is used. Assessments have been made of the possible potential risk of the induction of acute effects (photokeratitis, erythema) and of inducing malignant melanoma and non-malignant melanoma skin cancers resulting from exposure to commonly used fluorescent lamps. The optical absorption properties of materials commonly used in diffusers and controllers in commercial and domestic lighting units were also measured. Irradiance data, both weighted (for biological effectiveness) and unweighted, for various lamp types are presented in the report, together with some typical spectral output distributions. The results show that at commonly used illumination levels the UVR emissions from general and special fluorescent lamps presented neither an acute nor a significant chronic hazard. High UV-B emission levels were measured from 'U...

  10. Influence of ambient and enhanced ultraviolet-B radiation on the plant growth and physiological properties in two contrasting populations of Hippophae rhamnoides

    International Nuclear Information System (INIS)

    Two contrasting sea buckthorn (Hippophae rhamnoides L.) populations from low and high altitude regions were employed to investigate the effects of prevailing and enhanced ultraviolet-B (UV-B) radiation on plant growth and physiological properties under a UVB-enhanced/exclusion system. The experimental design included three UV-B regimes, including excluded (-UVB), near-ambient (NA) and enhanced UV-B (+UVB) radiation. Compared with the control (-UVB), NA caused the formation of smaller but thicker plant leaves in both sea buckthorn populations, paralleled with significant increments of carotenoids and UV-absorbing compounds as well as improved water economy. NA also induced more biomass partition from shoot to root, but CO2 assimilation rate (A), photosynthetic area and biomass accumulation were unaffected. The low-altitude population seemed sensitive to +uvB, as indicated by the decreases in total biomass, A and ascorbic acid content (Asa, an antioxidant) compared with NA. However, little +UVB effect occurred on the high-altitude population, and we suggest that the higher tolerance of this population could be associated with its specific morphological and physiological characteristics, such as small but thick leaves and high-level of Asa content, as well as its greater physiological modification in response to NA, e.g., increases in protective compounds (carotenoids and UV-absorbing compounds) and improvement in water economy, in comparison to the low-altitude population, which form an effective adaptation strategy to enhanced UV-B stress

  11. Hormone-controlled UV-B responses in plants.

    Science.gov (United States)

    Vanhaelewyn, Lucas; Prinsen, Els; Van Der Straeten, Dominique; Vandenbussche, Filip

    2016-08-01

    Ultraviolet B (UV-B) light is a portion of solar radiation that has significant effects on the development and metabolism of plants. Effects of UV-B on plants can be classified into photomorphogenic effects and stress effects. These effects largely rely on the control of, and interactions with, hormonal pathways. The fairly recent discovery of the UV-B-specific photoreceptor UV RESISTANCE LOCUS 8 (UVR8) allowed evaluation of the role of downstream hormones, leading to the identification of connections with auxin and gibberellin. Moreover, a substantial overlap between UVR8 and phytochrome responses has been shown, suggesting that part of the responses caused by UVR8 are under PHYTOCHROME INTERACTING FACTOR control. UV-B effects can also be independent of UVR8, and affect different hormonal pathways. UV-B affects hormonal pathways in various ways: photochemically, affecting biosynthesis, transport, and/or signaling. This review concludes that the effects of UV-B on hormonal regulation can be roughly divided in two: inhibition of growth-promoting hormones; and the enhancement of environmental stress-induced defense hormones. PMID:27401912

  12. Hormone-controlled UV-B responses in plants.

    Science.gov (United States)

    Vanhaelewyn, Lucas; Prinsen, Els; Van Der Straeten, Dominique; Vandenbussche, Filip

    2016-08-01

    Ultraviolet B (UV-B) light is a portion of solar radiation that has significant effects on the development and metabolism of plants. Effects of UV-B on plants can be classified into photomorphogenic effects and stress effects. These effects largely rely on the control of, and interactions with, hormonal pathways. The fairly recent discovery of the UV-B-specific photoreceptor UV RESISTANCE LOCUS 8 (UVR8) allowed evaluation of the role of downstream hormones, leading to the identification of connections with auxin and gibberellin. Moreover, a substantial overlap between UVR8 and phytochrome responses has been shown, suggesting that part of the responses caused by UVR8 are under PHYTOCHROME INTERACTING FACTOR control. UV-B effects can also be independent of UVR8, and affect different hormonal pathways. UV-B affects hormonal pathways in various ways: photochemically, affecting biosynthesis, transport, and/or signaling. This review concludes that the effects of UV-B on hormonal regulation can be roughly divided in two: inhibition of growth-promoting hormones; and the enhancement of environmental stress-induced defense hormones.

  13. Effects of Enhanced UV-B Radiation on Resistant Substances in Nostoc commune%增强的UV-B辐射对地木耳中抗逆性物质的影响

    Institute of Scientific and Technical Information of China (English)

    王弋博; 曲颖; 杨亚军

    2011-01-01

    The contents of photosynthetic pigment (Chla,carotenoid and phycobilin),free proline,soluble polysaccharide and trehalose in Nostoc commune and terrestrial blue alga were studied in glasshouse condition irradiated with biological effective UV-B radiation of 2.54 kJ·m-2·d-1 (T1),4.25 kJ m-2·d-1 (T2) and 8.35 kJ·m-2·d-1 (T3)(stimulating 12%,20%and 40% attenuation in stratospheric ozone at Lanzhou in summer,respectively).The results indicated that the contents of photosynthetic pigment accumulated under low dosage and short time treatment with UV-B radiation,but they would reduce under high dosage and long time treatment.The content of free proline and trehalose accumulated with T1,T2 and T3 UV-B radiation treatment.Comparing the increasing rate of the three treatments,one can see that the increasing rate was the maximum for T3,followed by that for T2,and the minimum was for T1.The accumulation of free proline and trehalose showed a positive correlation with UV-B radiation dosage.With the degradation of soluble poIysaccharide in Nostoc commune,trehalose increased under UV-Bradiation.One of the reasons of the adaption of Nostoc commune to enhanced UV-B radiation is the effective accumulation of resistant substances.%实验室条件下模拟兰州地区夏至臭氧层衰减12%、20%和40%时增强的UV-B辐射2.54kJ·m-2·d-1(T1)、4.25 kJ·m-2· d-1 (T2)和8.35 kJ·m-2·d-1(T3),研究了不同强度的UV-B辐射对陆生蓝藻地木耳(Nostoc commune)中的的抗逆性物质光合色素(叶绿素a、类胡萝卜素和藻胆素)、游离脯氨酸、可溶性粗多糖和海藻糖含量变化的影响.结果表明:低剂量、短时间的UV-B辐射增加地木耳中光合色素的积累,高强度、长时间的辐射使光合色素含量减少;T1、T2、T3处理均能引起脯氨酸和海藻糖的积累,且增长率是T1<T2<T3,表明脯氨酸和海藻糖的积累与UV-B辐射的剂量呈正相关.在UV-B辐射下,海藻糖的积累是伴随着地

  14. Influences of Drought and Enhanced UV-B Radiation on the Photosynthetic Pigment of Fagopyrum dibotrys%干旱及增强UV-B胁迫对金荞麦光合色素的影响

    Institute of Scientific and Technical Information of China (English)

    王雯; 张益锋

    2012-01-01

    [目的]研究干旱胁迫和增强UV-B辐射对金荞麦光合色素的影响,以期为金荞麦规范化种植提供理论依据.[方法]采用盆栽试验的方法,测定金荞麦在不同程度干旱胁迫和UV-B辐射处理下先合色素的含量,并计算光合色素比值.[结果]金荞麦叶绿素a含量、叶绿素b含量、总叶绿素含量、叶绿素a/叶绿素b、类胡萝卜素含量都随干旱程度的加重而降低,类胡萝卜素/叶绿素在处理中后期基本随干旱程度的加深而有升高的趋势,在后期达到显著水平;在水分充足的状况下,增强的UV-B辐射降低了叶绿素a、叶绿素b和总叶绿素含量,显著提高了类胡萝卜素含量和类胡萝卜素/叶绿素;在干旱胁迫下,增强的UV-B辐射提高了叶绿素b和总叶绿素含量.[结论]金荞麦光合色素对于旱胁迫敏感,且在一定程度上能指示反映叶片受伤害程度,并反映土壤干旱水平;增强的UV-B辐射能减小由干旱胁迫带来的金荞麦光合色素变化.%[Objective] To study the influences of drought stress and enhanced UV-B radiation on photosynthetic pigment of Fagopyrum dibotrys (D. Don) Hara.so as to provide a theoretical basis for the cultivation of F. Dibotrys. [ Method] By experiment of potted plant,the photosynthetic pigments of F. Dibotrys under different drought stresses and UV-B radiations were determined and its ratio was calculated. [ Result]Chlorophyll a, chlorophyll b, total chlorophyll, carotenoid contents and ratio of chlorophyll a/streophyll b in F. Dibotrys reduced with the severity of drought. Ratios of carotenoid to chlorophyll in F. Dibotrys showed a rising trend with the deepening drought and reached a significant level at the later stage. Under conditions of adequate water,enhanced UV-B radiation significantly reduced chlorophyll a,chlorophyll b and total chlorophyll contents in F. Dibotrys,and it also significantly increased the ratios of carotenoid/chlorophyll in F. Dibotrys

  15. UV-B exposure, ROS, and stress: inseparable companions or loosely linked associates?

    Science.gov (United States)

    Hideg, Eva; Jansen, Marcel A K; Strid, Ake

    2013-02-01

    Ultraviolet-B (UV-B) radiation has long been perceived as a stressor. However, a conceptual U-turn has taken place, and UV-B damage is now considered rare. We question whether UV-stress and UV-B-induced reactive oxygen species (ROS) are still relevant concepts, and if ROS-mediated signaling contributes to UV-B acclimation. Measurements of antioxidants and of antioxidant genes show that both low and high UV-B doses alter ROS metabolism. Yet, there is no evidence that ROS control gene expression under low UV-B. Instead, expression of antioxidant genes is linked to the UV RESISTANCE LOCUS 8 pathway. We hypothesize that low UV-B doses cause 'eustress' (good stress) and that stimuli-specific signaling pathways pre-dispose plants to a state of low alert that includes activation of antioxidant defenses.

  16. Responses of secondary chemicals in sugar maple (Acer saccharum) seedlings to UV-B, springtime warming and nitrogen additions

    Energy Technology Data Exchange (ETDEWEB)

    Sager, E.P.S.; Hutchinson, T.C. [Trent Univ., Peterborough, ON (Canada). Environmental Studies

    2006-10-15

    Elevated UV-B radiation due to climatic change and ozone depletion may represent a significant springtime environmental stressor to germinating seedlings in temperate forest regions. This study aimed to determine the effects of UV-B, nitrogen (N) fertilization and climate warming on the concentrations of base cations and secondary metabolites in the foliage of sugar maple seedlings growing in acid or alkaline soils. The influence of measured flavonoids and phenolics on herbivore activity was examined, as well as the relationship between foliar concentrations of calcium (Ca); manganese (Mn); and N and the production of phenolic and flavonoid compounds. Experimental plots were established in mature hardwood forests in alkaline and acid soil locations in Bobcaygeon and Haliburton, Ontario. Pentagonal open-top chambers were used to lengthen the growing season and simulate an earlier spring. Ammonium nitrate was applied at a rate comparable with an additional deposition of 5 g N per m per year. Fertilizer was applied on 3 separate occasions. Ambient UV-B radiation was screened out with Mylar D polyester film. Sites, treatments and time of sampling had complex effects on foliar elemental chemistry, production of secondary compounds and herbivory. Foliar concentrations of individual phenols were higher in seedlings in the UV-B exclusion treatments. At both sites, removal of ambient UV-B led to increases in flavonoids and chlorogenic acid, and reduced herbivore activity. At Haliburton, ammonium nitrate fertilization led to further increases in foliar Mn. Nitrogen additions led to decreases in the concentrations of some flavonoids at both sites. It was concluded that the composition of the forest soil governs the response of seedlings when they are exposed to abiotic stressors. 63 refs., 5 tabs., 8 figs.

  17. 低剂量微波辐射对增强UV-B辐射损伤菘蓝幼苗抗氧化酶活性的影响%Influence of Low Doses Microwave Radiation on Activities of Antioxidative Enzymes of Isatis indigotica Seedlings Exposed to Enhanced UV-B Radiation

    Institute of Scientific and Technical Information of China (English)

    陈怡平; 刘永军; 赵萌萌; 崔瑛

    2005-01-01

    In order to determine the damage repair role of microwave in the stress resistance of Isatis indigotica to UV-B radiation,the seedlings subjected to UV-B radiation of 10.08 kJ·m-2·d-1 for 8 h under photosynthetically active radiation (220 μmol·m-2·s-1) were exposed to microwave radiation of 0,3,6,9 and 12 s (126 mW·cm-2,2 450 MHz).Afterwards,changes of UV-B-injured leaves of the fourth in the activities of enzymes,such as SOD,CAT and POD,and in the concentration of malondialdehyde (MDA) and ascorbic acid (AsA),and UV absorbing compounds were measured to test the effects of microwave treatment.The results indicated when the seedlings were treated using 10.08 kJ·m-2·d-1 UV-B and then exposed to shorter microwave radiation,the activities of SOD,CAT and POD,and the concentration of AsA,and UV absorbing compounds increased significantly.UV-B-injured Isatis indigotica seedlings treated with microwave radiation recovered faster from enhanced UV-B stress resistance because the MDA concentration decreased compared with UV-B treatment alone.However,the repaired effect on seedlings injured by UV-B damage became weak,and even lost with the augment of microwave radiation time.Those changes in the vigor of enzymes and in concentration of MDA,AsA and UV-B absorbing compound suggested that microwave radiation of suitable time length had a positive physiological repair role on UV-B-damaged plants.However,the mechanisms of microwave repair effect in plants damaged by UV-B are not clear at present and additional work will be needed to investigate in the future.%为了探讨低剂量微波对增强UV-B辐射损伤菘蓝(Isatis indigotica Fort.)的修复作用,将经过10.08 kJ·m-2·d-1辐射损伤(PAR=220 μmol·m-2·s-1)的菘蓝幼苗分别经0、3、6、9和12 s等不同时间的微波辐照(126 mW·cm-2,2 450 MHz),然后测定其幼苗MDA含量、紫外吸收物质含量、抗坏血酸含量以及3种抗氧化酶SOD、CAT和POD活性.结果表明,增强UV-B辐射损伤

  18. Effect of enhanced UV-B radiation on metabolism and berberine content of Coptis chinensis%增强UV-B对黄连代谢及小檗碱含量的影响

    Institute of Scientific and Technical Information of China (English)

    温泉; 张楠; 曹瑞霞; 周心渝; 唐娟; 吴能表

    2011-01-01

    目的:测定黄连根中小檗碱含量对不同UV-B辐射强度的响应,为提高黄连小檗碱含量提供理论参考.方法:实验设置了CK(自然光),UL(0.05 W·m-2),UM(0.10 W·m-2),UH(0.20 W·m-2)4个处理组,探讨UV-B辐射下初生代谢中光合特性、PPP途径和次生代谢中酪氨酸酶及黄连根中的小檗碱含量的变化特性.结果:在UH辐射胁迫下,黄连叶片中光合色素、PSⅡ非光化学猝灭系数(qN),初始荧光(Fo),电子传递速率(ETR)以及6-磷酸葡萄糖脱氢酶活性、根中小檗碱含量均较其他组低.而处于UM辐射下的黄连,光合作用能力、PPP途径、酪氨酸酶活性以及小檗碱含量均高于对照组,产生了胁迫应激反应来抵御适度的UV-B辐射.结论:黄连处于UM辐射时,通过增强光合作用及PPP途径,能提供较多的次生代谢物前体物及次生代谢物所必需的NADPH,进而小檗碱的含量也相应提高,为黄连栽培种植中提高小檗碱含量提供参考.%Objective: To reveal the response of content berberine in root of Coptis chinensis to different intensity of UV-B radiation, and provide the theory basis for promoting the content of berberine. Method: Four groups of UV-B radiation were set in the experiment which included; natural light control (0 W · m-2) ,UL(0.05 W · m-2) ,UM(0.10 W · m-2) , UH(0.20 W · m-2). The special photosynthesis character, PPP pathway in the primary metabolism and lyrosinase activity, the changes of berberine in the root of C. chinensis were measured under different UV-B radiation. Result: Photosynthetic pigment, qN, Fo, ETR, activity of glucoses-phosphate dehydrogenase and the content of berberine in the root of C. chinensis, all of these parameters were lower than other groups under the UH radiation. However, under the UM radiation,C. chinensis protected itself from the light UV-B radiation by promoting the power of photosynthesis and PPP pathway in order to produce more NADPH and secondary metabolites

  19. Potassium phosphite increases tolerance to UV-B in potato.

    Science.gov (United States)

    Soledad, Oyarburo Natalia; Florencia, Machinandiarena Milagros; Laura, Feldman Mariana; Raúl, Daleo Gustavo; Balbina, Andreu Adriana; Pía, Olivieri Florencia

    2015-03-01

    The use of biocompatible chemical compounds that enhance plant disease resistance through Induced Resistance (IR) is an innovative strategy to improve the yield and quality of crops. Phosphites (Phi), inorganic salts of phosphorous acid, are environment friendly, and have been described to induce disease control. Phi, similar to other plant inductors, are thought to be effective against different types of biotic and abiotic stress, and it is assumed that the underlying signaling pathways probably overlap and interact. The signaling pathways triggered by UV-B radiation, for instance, are known to crosstalk with other signaling routes that respond that biotic stress. In the present work, the effect of potassium phosphite (KPhi) pre-treatment on UV-B stress tolerance was evaluated in potato leaves. Plants were treated with KPhi and, after 3 days, exposed to 2 h/day of UV-B (1.5 Watt m(-2)) for 0, 3 and 6 days. KPhi pre-treatment had a beneficial effect on two photosynthetic parameters, specifically chlorophyll content and expression of the psbA gene. Oxidative stress caused by UV-B was also prevented by KPhi. A decrease in the accumulation of hydrogen peroxide (H2O2) in leaves and an increase in guaiacol peroxidase (POD) and superoxide dismutase (SOD) activities were also observed. In addition, the expression levels of a gene involved in flavonoid synthesis increased in UV-B-stressed plants only when pre-treated with KPhi. Finally, accumulation of glucanases and chitinases was induced by UV-B stress and markedly potentiated by KPhi pre-treatment. Altogether, this is the first report that shows a contribution of KPhi in UV-B stress tolerance in potato plants.

  20. Effects of UV-B radiation on stems elongation and cell wall polysaccharides of pea seedlings%UV-B辐射对豌豆伸长生长和细胞壁多糖组分的影响

    Institute of Scientific and Technical Information of China (English)

    曲颖; 王弋博; 冯虎元; 程佳强; 李文建; 安黎哲

    2012-01-01

    In order to study the relationship between elongation growth inhibition induced by ultraviolet-B (UV-B) radiation and the changes of cell wall polysaccharides fraction;the stems length and contents of total sugar and uronic acid of cell wall polysaccharides fractions (pectin;hemicelluloses A;hemicelluloses B and cellulose) of pea stems irradiated with UV-B were analyzed. The results showed that with the sample of traditional pea;the stem length increased;while the amounts of cell wall polysaccharides per unit length decreased in primary 5 days;which showed a significantly negative correlation (p<0.05). However;the elongation growth of stems was inhibited and amounts of cell wall polysaccharides increased with UV-B irradiated sample. Under UV-B radiation;the stem length decreased by 7.35 cm and the amounts of cell wall polysaccharides increased by 0.07 mg/cm compared with control group on the 5th day. Compared with CK;the total sugar of pectin;hemicelluloses A;hemicelluloses B;and cellulose of UV-B irradiated group increased by 22.30%;42.30%;21.47%;and 12.05%;respectively;meanwhile the related uronic acid increased by 6%;33.3%;17.24%;and 18.08%;respectively. These results can be suggested that the metabolism of cell wall polysaccharides may be regulated by UV-B radiation. The changes of cell wall structure may be involved in cell wall thickness;which will lead to the cell wall rigidified. Therefore the extensibility of cell wall is decreased and elongation growth is inhibited.%为探讨紫外线-B (UV-B)辐射引起的豌豆幼苗生长抑制与细胞壁结构组分变化的关系,以豌豆幼苗为对象,研究UV-B辐射对豌豆幼苗株高、细胞壁多糖组分(包括果胶、半纤维素A、半纤维素B和纤维素)中总糖含量与醛酸含量的影响.研究结果表明:自然生长的豌豆幼苗,随着生长天数的增加,幼苗株高增加,但单位长度细胞壁多糖总量降低,两者呈显著负相关(p<0.05); UV-B辐射会抑制豌豆幼苗

  1. Effects of Enhanced UV-B Radiation on Amino Acid and Secondary Metabolite Contents in Mentha piperita L.%UV-B辐射对薄荷药用成分质量分数的影响

    Institute of Scientific and Technical Information of China (English)

    吴能表; 罗红丽; 马红群; 吴督督; 张扬欢; 胡丽涛; 孙金春

    2012-01-01

    To study the effects of UV-B radiation on amino acid and secondary metabolite contents in Mentha piperita L. , M. piperita plants were exposed to enhanced UV-B radiation at 0.15 and 0.35 W/m2 , and flavone, medicinal amino acids, and menthol, menthone, and P-menthone in the volatile oils were determined. Under 0. 15 W/m2 radiation stress, the content of flavone in the plants was significantly increased; the contents of Glu, Lys, Gly and menthol, menthone and P-menthone in the volatile oils were significantly decreased, while Leu and Phe first increased and then decreased, and the content of soluble proteins decreased significantly 20 and 30 days after the treatment. Under 0.15 W/m2 radiation stress, the content of flavone first increased and decreased later and reached the maximum after 30 days; the contents of Glu, Gly, Leu, Tyr, Phe and Arg and the sum of 9 medicinal amino acids were decreased significantly in 10--40 days, the content of soluble proteins was decreased 20 days after the treatment, and the contents of menthol, menthone, P-menthone in the volatile oils were increased significantly. It is concluded from the present work that low dosage UV-B radiation promoted the synthesis of the aromatic amino acid Phe and the branched-chain amino acid Leu while high dosage UV-B radiation decreased the contents of medicinal amino acids of M. piperita L, and that the M. piperita plants could increase the contents of the secondary metabolites such as flavone, menthol, menthone and P-menthone to enhance their adaptability to UV-B radiation.%目的:探讨增强UV-B辐射对胡椒薄荷氨基酸及药用次生代谢物质量分数的影响.方法:人工模拟生长环境中紫外辐射增强处理胡椒薄荷,用分光光度法测胡椒薄荷内黄酮质量分数,氨基酸采用日立L-8800型全自动氨基酸分析仪测定,薄荷挥发油中主要药用成分质量分数测定采用Agilent 6820气相色谱仪(配氢火焰检测器FID,美国安

  2. UV-B Radiation Induces Macrophage Migration Inhibitory Factor–Mediated Melanogenesis through Activation of Protease-Activated Receptor-2 and Stem Cell Factor in Keratinocytes

    OpenAIRE

    Enomoto, Akiko; Yoshihisa, Yoko; Yamakoshi, Takako; Ur Rehman, Mati; Norisugi, Osamu; HARA Hiroshi; Matsunaga, Kenji; Makino, Teruhiko; Nishihira, Jun; Shimizu, Tadamichi

    2011-01-01

    UV radiation indirectly regulates melanogenesis in melanocytes through a paracrine regulatory mechanism involving keratinocytes. Protease-activated receptor (PAR)-2 activation induces melanosome transfer by increasing phagocytosis of melanosomes by keratinocytes. This study demonstrated that macrophage migration inhibitory factor (MIF) stimulated PAR-2 expression in human keratinocytes. In addition, we showed that MIF stimulated stem cell factor (SCF) release in keratinocytes; however, MIF ha...

  3. 滤减UV-B辐射对烤烟蛋白质组变化的影响%Effects of reduced UV-B radiation on the variation of flue-cured tobacco proteome

    Institute of Scientific and Technical Information of China (English)

    陈宗瑜; 毕婷; 吴潇潇

    2012-01-01

    To understand the effects of different UV-B radiation intensity on the physiological metabolism and its regulatory pathways of flue-cured tobacco, two-dimensional gel electrophoresis and mass spectrum technique was adopted to study the physiological traits and protein expression profiles of Nicotina toboxcum L cv. "K326" , a flue-tobacco cultivar commonly planted in Yunnan Province, under the covering of different transparent films to reduce UV-B radiation. Two treatments were installed, i. e. , covering with polyethylene (treatment 1, 75. 8% UV-B radiation intensity) and Mylar (treatment II, 37.5% UV-B radiation intensity). In the two treatments, ten protein spots expressed significantly different. As compared in treatment I, five protein spots were up-regulated while the other five were down-regulated in treatment II. Among the ten protein spots, three were redox-related, three were photosynthesis-related, one was a kinase involved in energy metabolism, one was RNA-binding, and the other two were to be further identified. A preliminary research was also made on the effects of different UV-B radiation intensity on the physiological metabolism of "K326" at proteome level. During the physiological mature period, transition period, and process mature period of "K326" , the net photosynthetic rate (Pn) was significantly higher in treatment II than in treatment I, which was in accordance with the result mentioned above (three up-regulated proteins related with photosynthesis in treatment II). Comparatively, the "K326" in treatment I grew faster, and most of the morphological parameters such as stem girth and specific leaf mass were higher.%为研究不同UV-B辐射强度对烤烟生理代谢及调控途径的影响,应用蛋白质双向电泳联用质谱技术,以云南普遍种植的烤烟K326为试验材料,通过覆盖不同透明薄膜滤减UV-B辐射的方式,对75.8%(聚乙烯膜,处理1)和37.5%(麦拉膜,处理2)UV-B辐射透过率处理下K326的蛋白质

  4. Effects of ultraviolet radiation B (UV-B) on photosynthesis of natural phytoplankton assemblages in a marine bay in Southern China

    Institute of Scientific and Technical Information of China (English)

    YUAN XiangCheng; YIN KeDong; ZHOU WeiHua; CAO WenXi; XU XiaoQiang; ZHAO Di

    2007-01-01

    Solar ultraviolet radiation B (UVB) is known to have inhibitive effects on phytoplankton photosynthesis. UVB light decreases rapidly with increasing depth in the water column and exerts different degrees of UVB inhibitive effects on phytoplankton photosynthesis. In this study, the objectives were to quantify effects of UVB on phytoplankton photosynthesis and quantum yield, and to examine UVB effects on phytoplankton photosynthesis when light varies. The insitu experiments were conducted in Da Ya Bay, which is a semienclosed area in the subtropical South China. The results showed a significant reduction of photosynthetic rates and quantum yield in the presence of UVB. Maximum photosynthetic rates (Pmax) and maximum quantum yield (φmax) were 11%-22% and 17%-49% less under solar radiation with UVB than without UVB. A simplified model was developed to describe the UVB biologically effective fluence rate (E*inh) as an exponential decay function of depth. Light-shift experiments, in which water samples from the surface and at depth of 4 m were divided into several subsamples, and each subsamples were then incubated at different depths with and without UVB in the water column, showed that phytoplankton from the deeper water (4 m) had more inhibitive rates by UVB than that from the surface when exposed to the same light condition.

  5. Effects of UV-B radiation on ^15N urea absorption, utilization and distribution in fruiting shoot of peach under protected culture%UV-B辐射对设施桃结果枝~(15)N尿素吸收、利用及分配特性的影响

    Institute of Scientific and Technical Information of China (English)

    于妮娜; 谭秋平; 谭钺; 张海森; 高东升

    2012-01-01

    This study was conducted to determine the effects of UV-B radiation on 15 N absorption, utilization and as well as distribution in 2 year-fruiting shoot of peach under protected culture. The zero ( control), low, moderate and high intensities of UV-B radiation were conducted on six-year-old greenhouse-grown ' chunjie' peaches (Prunus persica ev. Chunjie). Leaves were fed with 15 N-labeled urea at the various stages of fruit development. Subsequently, leaves, fruits and branches were respectively harvested for the determination. The Ndff levels of the sampled organs are increased under the UV-B irradiation, and are distinctively influenced at various phonological phases. At the fruit-swelling stage, the highest Ndff levels of most organs are detectable under either the moderate and high intensity of UV-B radiation condition, except for those of biennial branches under the low intensity of UV-B radiation. At the core-hardening stage, the highest Ndff levels in vegetative organs are examined under either moderate or high intensity of UV-B radiation condition, and yet the low intensity of UV-B radiation condition is responsible for those in both flesh and stone. At the fruit-coloring stage, the moderate intensity of UV-B radiation condition turns out to contribute to the highest Ndff levels in organs determined. It indicates that the UV-B radiation raise 15N utilization efficiency notably by bearing branches. At the fruit-swelling stage, the high intensity of UV-B radiation condition exerts significantly distinct consequences on ^15N distribution to the tested organs. At fruit-swelling stage, higher intensive UV-B radiation significantly raised the utilization efficiency of ^15N (50.28%), while at stages of core-hardening and fruit-coloring, the utilization efficiencies of ^15N peaked under moderate intensity of UV-B radiation condition, with significant increase by 83.99% and 105.56% compared to control, respectively. At the fruit-swelling and fruit

  6. Antarctic marine bacteria versus UV-B irradiation

    International Nuclear Information System (INIS)

    The most important stages of knowledge development in Antarctic marine microbiology, from the beginning of this century, were reviewed and systematized. Multi-annual studies from 1978 to 1988 demonstrated a great variation in total and saprophytic bacterial numbers at different sites in the Antarctic. These sites included inshore waters (Admiralty Bay), open ocean waters (Drake Passage and Bransfield Strait), and the vicinity of pack-ice in Scotia Sea. Bacterial biomass, which is highly comparable to that of other organisms, combined with many times shorter bacterial generation time, (in case of saprophytic population it amounts to 17.5 h), must have profound consequences for cold marine ecosystems of the Antarctic. Higher numbers of bacteria were found in open surface waters, down to 75 m. High transparency of oceanic offshore waters causes that UV radiation (280-400 nm) penetrates to biologically effective depths to about 50 m. The UV-B sensitivity of 25 Antarctic bacterial strains from the following various habitats: coastal waters, krill stomach, krill feaces, water ice edge, water below ice and sea ice was examined. The strains were irradiated in UV-B transparent cuvettes on an optical bench with artificial UV-B (290 nm; 1.21 W. m-2 ] during 10 hours in temperature 4oC. ATP (adenosine triphosphate), number of bacterial cells, lethal effect of UV-B and survival of bacteria, total bacterial number, biovolume and changes in biochemical/physiological properties have been estimated. The results indicated a high interspecific variability in the sensitivity against UV-B. The ATP content show at the beginning of irradiation an increase (reaching typical for individual species maximum, at 0.5 to 4 hours) and afterwards a decrease to the level above zero (also characteristic of species). We hypothesize that first anabolic processes and after that catabolic processes are destroyed by UV. Survival of the bacterial strains ranged between 0 and 3.2%. Among 25 bacterial

  7. Transcriptomic, proteomic and metabolomic analysis of maize responses to UV-B: Comparison of greenhouse and field growth conditions

    OpenAIRE

    Casati, Paula; Campi, Mabel; Morrow, Darren J; Fernandes, John; Walbot, Virginia

    2011-01-01

    UV-B radiation from normal solar fluence elicits physiological and developmental changes in plants under fluctuating environmental conditions. Most UV photobiology studies in plants utilize controlled greenhouse and growth chamber environments in which few conditions vary except the brief presence of UV-B radiation. Our purpose was to compare responses to UV-B in irradiated and shielded maize organs in field (natural solar plus 2x solar supplementation for defined periods) and greenhouse (2x ...

  8. 紫外线B辐射增强对杂交稻籼型恢复系结实率和千粒重的影响%Effect of Enhanced UV-B Radiation on Seed Setting Rate and 1 000-grain Weight of Indica Hybrid Rice Restorer Lines

    Institute of Scientific and Technical Information of China (English)

    况浩池; 曾祥瑞; 罗俊涛; 曾正明; 杨扬; 陈光珍; 何兴材; 付均

    2013-01-01

    [Objective] This study was to investigate the effect of enhanced UV-B radiation on seed setting rate and 1 000-grain weight of hybrid rice combinations.[Method] The seed setting rate and 1 000-grain weight of 10 new sterile indica restorer lines planted in pots under enhanced UV-B radiation and fluorescent lamps (control) were respectively measured,and the differences were compared.[Result]The enhanced UV-B radiation significantly reduced the seed setting rate of indica restorer lines,and the differences between that UV-B radiation treatment and control all reached extremely significant level.In addition,the enhanced UV-B radiation reduced the 1 000-grain weight of most indica restorer lines,and compared with that of control the difference achieved significant or very significant level.However,the effect of enhanced UV-B radiation on seed setting rate and 1 000-grain weight differed to different indica restorer lines,and the differences among restorer lines tested were significant or very significant,which indicated the possibility to screen antiUV-B radiation rice materials and combinations.Finally,the indica restorer lines 09R-14,Luhui 37 and 10R-7703 which were strongly resistant to UV-B radiation were screened out.[Conclusion] This study laid foundation for breeding hybrid rice varieties resistance to UV-B radiation.%[目的]研究UV-B辐射增强对杂交稻组合及亲本的影响.[方法]通过盆栽和增强UV-B辐射试验,研究了UV-B辐射增强对10个新育籼型恢复系结实率和千粒重的影响.[结果]UV-B辐射增强导致籼型恢复系结实率明显下降,与对照相比差异全部达到极显著水平;UV-B辐射增强导致绝大多数籼型恢复系千粒重下降,与对照相比差异达到显著或极显著水平.但UV-B辐射增强对不同籼型恢复系结实率和千粒重的影响程度差异较大,参试恢复系之间达到显著或极显著差异水平,这一结果预示着筛选抗UV-B辐射的杂交水稻育种材料和

  9. UV-B effects on crops: response of the irrigated rice ecosystem

    International Nuclear Information System (INIS)

    Increasing ultraviolet-B (UV-B) radiation resulting from depletion of the stratospheric ozone layer could have damaging effects on crops. This paper reviews recent findings on direct effects of UV-B on rice growth and yield as well as indirect effects via impacts on other organisms in the rice (Oryza sativa) agroecosystem. The findings are based on research by scientists at the International Rice Research Institute (IRRI) in Los Baños, the Philippines, and their collaborators in China and the United States; with comparison to research by scientists in other countries. Current results indicate that while enhanced UV-B directly impacts many aspects of rice growth, physiology, and biochemistry under controlled phytotron conditions; in general rice growth and yield are not affected under natural field conditions. The difference in response may be related both to the levels of UV-B exposure used in phytotron vs. field studies and the lower ratio of UV-A to UV-B in the phytotron compared to field. In terms of indirect effects on rice blast disease, enhanced UV-B affected both the fungus itself (Pyricularia grisea) and the susceptibility of the rice plant to the fungus. Based on these data, simulation models estimated potential impacts of higher UV-B levels on blast severity and rice yield in different countries of southeast and east Asia. Ultimately, results from rice studies can be used to identify strategies to minimize any negative effects of UV-B on rice productivity

  10. Pollen sensitivity to ultraviolet-B (UV-B) suggests floral structure evolution in alpine plants.

    Science.gov (United States)

    Zhang, Chan; Yang, Yong-Ping; Duan, Yuan-Wen

    2014-03-31

    Various biotic and abiotic factors are known to exert selection pressures on floral traits, but the influence of ultraviolet-B (UV-B) light on the evolution of flower structure remains relatively unexplored. We have examined the effectiveness of flower structure in blocking radiation and the effects of UV-B on pollen viability in 42 species of alpine plants in the Hengduan Mountains, China. Floral forms were categorized as either protecting or exposing pollen grains to UV-B. The floral materials of plants with exposed and protected pollen grains were able to block UV-B at similar levels. Exposure to UV-B radiation in vitro resulted in a significantly greater loss of viability in pollen from plant species with protective floral structures. The pronounced sensitivity of protected pollen to UV-B radiation was associated with the type of flower structure. These findings demonstrate that UV-B plays an important role in the evolution of protective floral forms in alpine plants.

  11. Quantitative changes in secondary metabolites of dark-leave willow (Salix myrsinifolia) exposed to enhanced ultraviolet-B radiation

    Energy Technology Data Exchange (ETDEWEB)

    Tegelberg, R.; Julkunen-Tiitto, R. [Univ. of Joensuu, Dept. of Biology, Joensuu (Finland)

    2001-07-01

    This is a study of the impact of increased ultraviolet-B (UV-B) radiation on the secondary chemistry of Salix myrsinifolia (dark-leave willow). For nearly two decades, the loss of stratospheric ozone above the high latitudes of the Northern Hemisphere has increased UV-B radiation (280-320 nm) over the long-term mean. Willows (Salicaceae) are widely distributed in these northern regions. To determine the effects of increased UV-B radiation on willows, the plantlets of three clones of S. myrsinifolia were grown under ambient (3.6 kJ m{sup -2} day{sup -1}) or enhanced (7.18 kJ m{sup -2} day{sup -1}) UV-B irradiance. After the 2-week indoor experiment, the concentrations of UV-B-screening phenolics (flavonoids and phenolic acids) and low-UV-B-screening phenolics (salicylates and condensed tannins) in fresh leaves were investigated and the biomass of leaves, stems and roots was determined. As expected, the total amount of flavonoids in willow leaves clearly increased when plantlets were exposed to higher UV-B irradiation. However, the degree of increase of individual compounds varied: luteolin-7-glucoside, monomethyl-monocoumaryl-luteolin-7-glucoside and one myricetin derivative increased significantly, while the apigenin-7-glucuronide increased only slightly. The enhanced UV-B also increased the amount of p-hydroxycinnamic acid derivative. The UV-B effects on other phenolic acids and tannins were minor. In contrast to the other phenolics, the amounts of two salicylates, salicin and saligenin, decreased under enhanced UV-B irradiation. Our results indicate that the concentrations of both UV-B-screening and low-UV-B-screening phenolic compounds in leaves of S. myrsinifolia may vary in response to elevated UV-B radiation. However, while the UV-B protective flavonoids and phenolic acids accumulate during UV-B exposure, the concentrations of certain salicylates decrease. (au)

  12. Effects of laser pretreatment on cells of broad bean in UV-B-induced damage protection%激光预处理可保护蚕豆细胞免受UV-B辐射的损伤

    Institute of Scientific and Technical Information of China (English)

    齐智; 岳明; 王勋陵

    2000-01-01

    The embryos of broad bean (Vicia faba L.) were irradiated for 5 min by a He-Ne laser (632.8 nm,1.63 J·mm-2) or for 1 min by a CO2 laser (1,060 nm,2.53 J·mm-2).Afterwards they were cultivated in Petri dish in the constant temperature incubator in Knop until the length of epicotyl of broad bean was perhaply 3 cm that could be treated by ultraviolet-B (UV-B) radiation.The epicotyl of broad bean was irradiated for 7 h by 1.02,3.03,4.52 kJ·m-2 UV-B respectively in the ambient condition of 70 μmol·m-2·s-1 photosynthetically active radiation (PAR) in the growth cabinet.According to the changes of content of MDA,ascorbate acid (AsA) and UV-B absorbing compounds (absorbance at 300 nm),the effects of protecting of laser to the epicotyl of broad bean from UV-B radiation were tested.The results showed that laser pretreatment on the embryos could enhance the resistance of UV-B stress in epicotyl.Comparing with the control (without UV-B or laser radiation) and UV-B radiation alone,the MDA content was decreased significantly while AsA content was increased in the condition of laser pretreatment.It was also found that laser pretreatment alone could improve the content of UV-B absorbing compounds.If laser pretreatment followed UV-B radiation,the content of UV-B absorbing compounds was improved higher than laser treatment and UV-B treatment respectively.We suppose that laser pretreatment could enhance stress resistance in plant by a pathway of increasing the content of AsA and UV-B absorbing compounds while decreasing the MDA concentration.%当蚕豆的胚被He-Ne激光(632.8 nm,1.63 J·mm-2)照射5 min或被CO2激光(1060 nm,2.53 J·mm-2) 照射1 min后,将其置入Knop营养液中进行恒温培养.当蚕豆的上胚轴长到大约3 cm时,在光背景(PAR)为70 μmol·m-2·s-1条件下,分别用1.02、3.03、4.52 kJ·m-2的UV-B 辐射蚕豆的上胚轴7 h.根据蚕豆丙二醛(MDA)、抗坏血酸(AsA)和UV-B吸收物的含量变化,来测试激光对UV-B照射蚕豆的上

  13. Combined Effects of Cd and Enhanced UV-B Radiation on Growth and Physiology of Winter Wheat Seedling%镉和UV-B辐射增强复合胁迫对冬小麦幼苗生长和生理的影响

    Institute of Scientific and Technical Information of China (English)

    何永美; 湛方栋; 徐渭渭; 高召华; 李元; 祖艳群

    2013-01-01

    The effects of the individual and combined cadmium(Cd), enhanced UV-B radiation on the growth and physiology of winter wheat were studied with seeds germination and pot experiments. Results showed that: (1)No significant effect of the Cd and enhanced UV-B radiation individual or combined stress on seeds germination rate of winter wheat was observed. The growth of winter wheat seedlings was inhibited significantly. The inhibitory effects with the combined stress were significantly greater than with a single stress.(2)The chlorophyll contents in winter wheat leaves decreased significantly and the flavonoid contents increased significantly under enhanced UV-B radiation. The effects of Cd stress were not obvious. The effects of enhanced UV-B radiation on chlorophyll and flavonoid contents did not intensify with the combined Cd stress. (3)The cell membrane permeability of winter wheat leaves increased significantly with individual Cd or enhanced UV-B radiation stresses. The MDA contents increased significantly with Cd stress. The effects of Cd stress on the MDA contents in winter wheat leaves were promoted by the combined enhanced UV-B radiation.(4)The contents of Cd in winter wheat shoots under Cd and enhanced UV-B radiation combined stresses were significantly higher than that under Cd stress. These results indicate that there were additive effects of Cd and enhanced UV-B radiation combined stress on the growth and physiology of winter wheat.%通过种子萌发和盆栽试验研究了镉(Cd)与UV-B辐射增强单独和复合胁迫对冬小麦幼苗生长和生理的影响,结果表明:(1)Cd与UV-B单独或复合胁迫对冬小麦种子萌发率没有显著影响,但明显抑制冬小麦幼苗的生长,复合胁迫的抑制效应明显大于单一胁迫;(2)UV-B辐射增强导致冬小麦叶片的叶绿素含量显著或极显著下降,类黄酮含量极显著增加,Cd胁迫没有显著影响,且复合Cd胁迫后不加剧UV-B辐射对冬小麦叶片叶绿素

  14. Influences of enhanced UV-B radiation and drought stress on biomass accumulation and allocation of Fagopyrum dibotrys%干旱及增强UV-B胁迫对金荞麦生物量积累与分配的影响

    Institute of Scientific and Technical Information of China (English)

    张益锋; 何平; 张春平

    2011-01-01

    目的:研究干旱胁迫和增强UV-B辐射对金荞麦生物量积累与分配的影响,以期作为金养麦规范化种植提供科学理论依据.方法:采用盆栽试验的方法,测定金养麦在不同程度干旱胁迫和UV-B辐射处理下各器官生物量,并计算生物量分配的情况.结果:在充足水分状况下:增强UV-B辐射显著降低了金荞麦各器官生物量积累,降低了金荞麦根生物量配置,提高了金养麦茎生物量配置.在中度干旱胁迫下,增强的UV-B辐射提高了金荞麦根生物量积累和配置、茎生物量积累.在重度干旱胁迫下,增强的UV-B辐射提高了金养麦根生物量积累,能使金荞麦茎生物量积累得到一定提高,金荞麦各器官生物量配置对增强UV-B辐射均不甚敏感.结论:增强的UV-B辐射对金荞麦生物量积累和分配的影响因水分状况的差异和器官的差异而不同.总体看来,基本证实了增强UV-B辐射能减轻干旱胁迫对金荞麦生物量积累的影响.%Objective;To study the influences of enhanced UV-B radiation and drought stress on the biomass accumulation and allocation of Fagopyrum dibotrys, and so as to provide a theoretical basis for the cultivation, the protection and use of F. dibotrys. Method; By experiment of potted plant, the biomass accumulation and allocation of F. dibotrys were measured under different drought stresses and UV-B radiations. Result; In conditions of adequate water, enhanced UV-B radiation significantly reduced biomass accumulation to root, biomass accumulation to leaves, total biomass accumulation and biomass allocation to root in F. dibotrys, while it could increase biomass allocation to stem. In conditions of moderate drought stress, enhanced UV-B radiation increased biomass accumulation to root, biomass accumulation to stem and biomass accumulation to root. In the conditions of severe drought stress, enhanced UV-B radiation increased biomass accumulation to root, it also could lead in a

  15. 不同时期减弱UV-B辐射对烤烟部分生理生化特征的影响%Effects of Reduced UV-B Radiation on Partial Physiological and Chemical Characteristics of Flue-cured Tobacco in Different Growing Stage

    Institute of Scientific and Technical Information of China (English)

    简少芬; 董卓娅; 陈宗瑜; 田先娇; 谭淑文; 吴潇潇; 颜侃

    2011-01-01

    采用大棚加盖Mylar膜的方法,在大田条件下研究了烤烟不同生育期(旺长期、生理成熟期和工艺成熟期)减弱UV-B辐射(相当于自然环境下强度的39.59%)对不同叶位叶片含水量(LWC)、比叶重(SLW)、光合色素、类黄酮(Fv)和丙二醛(MDA)等的影响.结果表明,旺长期减弱UV-B辐射对烟叶LWC影响较小,但可降低中、下部烟叶的SLW,生理成熟期和工艺成熟期减弱UV-B辐射可降低中、上部叶的LWC,但可提高其SLW值.旺长期和生理成熟期减弱UV-B辐射可降低中部叶的叶绿素a(chl a)、b(chl b)含量,工艺成熟期减弱UV-B辐射后中、上部叶的chla、b含量上升.旺长期和生理成熟期减弱UV-B辐射降低MDA含量,FV和类胡萝卜素(car)变化与MDA基本相反.结果说明,旺长期较强的UV-B辐射有利于提高烟叶的SLW,旺长期和生理成熟期较强的UV-B辐射还可促进chl和car的合成,MDA的变化与FV和car有一定的关系.%The effects of reduced UV-B radiation (39. 59% of natural intensity) .which was obtained by covering with Mylar plastic membrane,on leaf water content ( LWC) .specific leaf weight (SLW) ,photosynthetic pigments,flavonoid ( FV) and malondialdehyde ( MDA) of different leaf positions in tobacco variety K326 were studied in different growing stages, e. G. Fast-growing period, physiological maturity period and technological maturity period, with field experiment The results showed that there was a little influence of reduced UV-B radiation on LWC in fast-growing period, whereas SLW of middle and bottom leaves were decreased. UV-B radiation reduction in physiological maturity period and technological maturity period reduced LWC of middle and upper leaves, but improved SLW. Chlorophyll a and b ( chl a,chl b) of middle leaf were decreased by reduced UV-B radiation in fast-growing period and physiological maturity period. However,chl a and chl b of middle and upper leaves were increased by UV-B radiation reduction in

  16. 增强UV-B辐射及氮水平对长春花生长和生理代谢的影响%The Effects of Supplementary UV-B Radiation and Nitrogen Levels on the Growth and Physiological Metabolism of Catharanthus roseus

    Institute of Scientific and Technical Information of China (English)

    郭晓瑞; 汪红玲; 王化楠; 段喜华

    2011-01-01

    The increased UV-B radiation and nitrogen deposition have become two important environmental factors affecting plant growth. Here, a medical plant Catharantkus roseus was subjected to altered UV-B and nitrogen level to study their influence in a sole or combined way on growth and vinblastine production. Our results showed that the UV-B exerted an obviously adverse effect on plant growth and biomass accumulation. The UV-B stress also led to physiological damages, for instance, the elevated MDA content. The increased supply with nitrogen nutrition could largely alleviate the inhibitory effects and damage symptom induced by UV-B stress. The UV-B absorbing compounds were enhanced remarkably by the supplementary UV-B radiation, and it was increased further when the nitrogen nutrition were supplied. The vinblastine content was increased markedly in the supplementary UV-B radiation, and which were increased further when the nitrogen supply increased. It was concluded that an increased nitrogen supply could not only alleviate the inhibitory effect of UV stress on plant growth, but enhance vinblastine accumulation in plants. We proposed that enrichment of nitrogen nutrition provide more N source for alkaloid synthesis induced by UV-B radiation, eventually resulting in increased alkaloid content.%地表UV-B辐射增强和氮沉降增加目前已成为影响植物生长的重要生态因子.本文以药用植物长春花(Catharanthus roseus)为材料,研究UV-B辐射和氮供应增加对长春花生长、生理及长春碱含量的协同效应.研究结果表明,紫外辐射增加对长春花生长和生物量积累具有显著的抑制作用.同时外源增加氮供应能明显缓解紫外辐射引起的生长抑制效应.紫外辐射引起的叶片膜脂过氧化胁迫导致了长春花叶片丙二醛含量显著增加,但同时增加氮供应能显著降低丙二醛水平.增强UV-B辐射处理显著促进长春花叶片UV-B吸收化合物合成积累,并随氮供应

  17. Effects of enhanced UV-B radiation on population quantity dynamics of weeds,soil macroanimals and wheat aphids in the wheat field ecosystem%增强的UV-B辐射对麦田生态系统中种群数量动态的影响

    Institute of Scientific and Technical Information of China (English)

    李元; 王勋陵

    2001-01-01

    研究了大田栽培和自然光条件下,模拟UV-B辐射(UV-B,280~315nm)增强对麦田生态系统杂草、大型土壤动物和麦蚜种群数量动态的影响。在UV-B辐射下,杂草和大型土壤动物的种类和数量降低,物种多样性改变,杂草总生物量也降低。UV-B辐射降低麦蚜复合种群数量,并与麦叶粗纤维、可溶性蛋白、可溶性糖、Mg和Zn含量有显著的相关性。UV-B辐射还导致麦蚜与麦叶Mg、Fe和Zn含量均显著增加。%Influences of enhanced ultraviolet radiation(UV-B,280~315nm)on population quantity dynamics of weeds,soil macroanimals and wheat aphids in the wheat field ecosystem were investigated,Under UV-B radiation,species number and population quantity of weeds and soil macroanimals decreased,species diversity changed,total biomass of weeds reduced.UV-B radiation decreased population quantity of wheat aphids,which were significantly correlated with HCel,soluble protein content,CHO and the concentrations of Mg and Zn in wheat leaves.UV-B radiation resulted in significant increase of the concentrations of Mg,Fe and Zn in wheat aphids and wheat leaves.

  18. UV-B-induced Oxidative Damage and Protective Role of Exopolysaccharides in Desert Cyanobacterium Microcoleus vaginatus

    Institute of Scientific and Technical Information of China (English)

    Lan-Zhou Chen; Gao-Hong Wang; Song Hong; An Liu; Cheng Li; Yong-Ding Liu

    2009-01-01

    UV-B-induced oxidative damage and the protective effect of exopolysaccharides (EPS) in Microcoleus vaginatus, a cyanobacterium isolated from desert crust, were investigated. After being irradiated with UV-B radiation, photosynthetic activity (Fv/Fm), cellular total carbohydrates, EPS and sucrose production of irradiated cells decreased, while reducing sugars, reactive oxygen species (ROS) generation, malondialdehyde (MDA) production and DNA strand breaks increased significantly. However, when pretreated with 100 mg/L exogenous EPS, EPS production in the culture medium of UV-B stressed cells decreased significantly; Fv/Fm, cellular total carbohydrates, reducing sugars and sucrose synthase (SS) activity of irradiated cells increased significantly, while ROS generation, MDA production and DNA strand breaks of irradiated cells decreased significantly. The results suggested that EPS exhibited a significant protective effect on DNA strand breaks and lipid peroxidation by effectively eliminating ROS induced by UV-B radiation in M. vaginatus.

  19. DETECTION OF UV-B-INDUCED THYMINE DIMER IN A CYANOBACTERIUM, SCYTONEMA SP.

    Directory of Open Access Journals (Sweden)

    Pavan Kumar

    2014-02-01

    Full Text Available DNA molecule is one of the major targets for UVR that can alter its molecular structure by forming different types of lesions leading to chronic mutagenic and even death of the cell. In comparison to UV-B, the wavelength of UV-A has poor efficiency in inducing the DNA damage; because they are not absorbed by native DNA. Before assessing the impact of UV-B radiation on DNA, we observed its effects on growth and survival of the test organism Scytonema sp. It was observed that growth and survival were severely affected by UV-B radiation for different durations. UV-B treatment causes loss in the cooperative binding property of DNA which is evident from the failure of complementary strands of DNA.

  20. UV-B辐射对元阳梯田水稻根系LMWOAs分泌量和根际微生物数量的影响%Effects of UV-B radiation on rice roots-exudated LMWOAs and rhizospheric microorganism quantities in a paddy field of Yuanyang Terraces, Yunnan Province

    Institute of Scientific and Technical Information of China (English)

    何永美; 湛方栋; 吴炯; 高召华; 李元

    2016-01-01

    在元阳梯田地方水稻品种———白脚老粳的拔节孕穗期、抽穗扬花期和成熟期,通过小区实验研究不同UV-B辐射强度(0、5.0、10.0 kJ·m-2)对水稻根系低分子量有机酸(LMWOAs)分泌量和根际7个类群微生物数量的影响,并对水稻LMWOAs分泌量和根际微生物数量进行相关分析。结果表明:UV-B辐射增强导致水稻根系草酸和琥珀酸分泌量增加,酒石酸和苹果酸分泌量下降。水稻根际细菌、真菌、自生固氮菌、纤维分解菌、无机磷细菌和钾细菌的数量均在成熟期最大,拔节孕穗期次之,抽穗扬花期最小;但放线菌数量在拔节孕穗期最大,抽穗扬花期次之,成熟期最小。UV-B辐射增强不改变根际微生物数量随生育期进程的动态变化规律,但导致水稻根际7个类群微生物的数量显著或极显著增加。水稻根系草酸分泌量与根际自生固氮菌、纤维分解菌数量呈显著正相关,琥珀酸分泌量与自生固氮菌数量呈显著正相关,与细菌、真菌、纤维分解菌、无机磷细菌和钾细菌数量呈极显著正相关。综上可知UV-B辐射增强影响大田水稻根际微生物的数量,与其改变水稻根系低分子量有机酸的分泌量密切相关。%A local rice variety,“Baijiaolaojing”, was grown in a paddy field in the Yuanyang Terrace under ambient and elevated(5.0 and 10.0 kJ·m-2)ultraviolet-B(UV-B, 280~315 nm)radiation. The rice plant and rhizospheric soil were sampled at jointing-booting, heading-flowering and maturity stages of rice. The exudation of low-molecular-weight organic acids(LMWOAs)including oxalic acid, succinic acid, tartaric acid, and malic acid by rice roots and the quantity of 7 microbial groups in rice rhizosphere were determined. Results showed that elevated UV-B radiation increased the concentrations of oxalic acid and succinic acid, but decreased tartaric acid and malic acid. Rhizo-spheric bacteria

  1. Combined effects of water, nutrient, and UV-B stress on female fitness in Brassica (Brassicaceae)

    International Nuclear Information System (INIS)

    Our knowledge of the effects of increased levels of ultraviolet-B radiation (UV-B) on plant fitness is limited mainly to yield studies in a few crop species. Previous greenhouse and garden studies of Brassica have found greater detrimental effects of UV-B on fitness in gardens than in the greenhouse, suggesting the possibility that additional stresses in the field decrease the ability of Brassica to cope with UV-B. Possible interactions between UV-B and water/nutrient stress in determining plant fitness have rarely, if ever, been studied experimentally. Here we report measurements of female fitness in two species of Brassica in an experiment in which both UV-B and levels of water and nutrients were varied in a 2 X 2 factorial design. Water and nutrient stress reduced female fitness in both species, while UV-B caused fitness reductions in only one of the species. There was evidence for interactions between UV-B and water/nutrient stress for only a few of the traits measured; most traits, including those closely related to fitness, showed no evidence of an interaction

  2. UV-B辐射增强对红松幼苗针叶脂质过氧化及抗氧化系统的影响%Effects of Elevated UV-B Radiation on Lipid Peroxidation and Antioxidant System in Needles of Pinus koraiensis seedling

    Institute of Scientific and Technical Information of China (English)

    魏晓雪; 于景华; 李德文; 佟璐; 庞海河; 祖元刚

    2011-01-01

    The 3-year-old pot-cultured Pinus koraiensis seedlings were used in this experiment. The seedings were treated with the following treatments; CK (Control), T1 treatment (3.25 μW·cm-2 UV-B radiation), T2 treatment (6.51 μW·cm-2 UV-B radiation) and T3 treatment (9. 76 μW ·cm-2 UV-B radiation). Effects of UV-B radiation on the concentration of free radical, the degree of lipid peroxidation and antioxidant system in needles of P. koraiensis were determined after 40 days of UV-B treatment. The results showed that the elevated UV-B radiation significantly increased concentrations of hydroxyl radical ( · OH), hydrogen peroxide radicals ( H2O2 ) and malondialdehyde (MDA) ( P < 0. 05). The concentrations of H2O2( 149. 05 mmol·g-1 ) and MDA ( 12. 56 μmol·g-1 ) were maximal under T3 treatment.The elevated UV-B radiation induced the activities of catalase ( CAT), ascorbate peroxide ( APX ), and superoxide dismutase ( SOD), but significantly decreased the activity of peroxidase (POD) (P < 0. 05 ). Concentration of soluble protein was increased with exposure to UV-B radiation (CK treatment was 0. 17 mg·g -1, while T3 treatment was 0. 26 mg·g-1). Carotenoid and flavonoid were decreased significantly by all UV-B radiations treatments. Simultaneously, the results of correlation analysis showed that the concentration of soluble protein had significant positive correlations with the concentrations of free radical and MDA ( P < 0. 01 ), and the concentration of hydroxyl radical had significant negative correlations with the concentrations of carotenoid and flavonoid ( P < 0. 01 ). This study demonstrated that the supplemental UV-B radiation increased the concentration of free radical and affected the physiological metabolism in needles of P. koraiensis seedlings. Simultaneously, P. koraiensis was able to increase the activities of CAT, APX, SOD and the concentration of soluble protein against oxidative stress injury caused by supplemental UV-B radiation, but the

  3. 紫外线照射对梁平柚果皮基因表达的影响%Effect of UV-B Radiation on Gene Expression in Peels of'Liangping'Pommelo[Citrus grandis(L.)Osbeck

    Institute of Scientific and Technical Information of China (English)

    程春振; 朱世平; 吴波; 阳佳位; 贝学军; 马岩岩; 钟广炎

    2011-01-01

    A suppression subtractive hybridization library was successfully constructed using cDNA synthesized from RNA extracted from peels of 'Liangping' pemmelo[Citrus grandis (L.) Osbeck]receiving UV-B radiation as tester and non-UVB treatment as driver.Two hundred randomly-picked positive clones were sequenced, and a total of 168 EST sequences were obtained.One hundred and fourteen ESTs, involving in 57 genes, were found to share considerable homology with known genes while the rest 54 ESTs had low or even no homology with known genes.Function analysis showed that these differentially expressed genes were related to numerical celluar events such as stress-tolerance, growth and development, cell apoptosis, cell differenciation, gene transcription and translation, signaling, energy metabolism, carbohydrate and amino acid metabolism and secondary metabolism.%采用SSH技术以紫外照射的梁平柚[Citrus grandis(L.)Osbeck]果皮作为实验方(tester),以未被照射的正常果皮作为驱动方(driver),构建了一个梁平柚果皮紫外诱导基因的正向差减文库.经菌液PCR检测后随机挑取200个阳性克隆测序,获得168条表达序列标签(ESTs).比对这168条ESTs,发现有分属于57个基因的114条ESTs与已知基因高度同源,54条ESTs同源性较低或没有同源性.功能分析发现,这些ESTs主要参与抗逆防御、生长发育、细胞凋亡、转录与翻译、细胞分化、信号传导、能量代谢、糖类及氨基酸代谢以及次生代谢等.

  4. Stratospheric ozone depletion : High arctic tundra plant growth on Svalbard is not affected by enhanced UV-B after 7 years of UV-B supplementation in the field

    NARCIS (Netherlands)

    Rozema, Jelte; Boelen, P.; Solheim, B.; Zielke, M.; Buskens, A; Doorenbosch, M.; Fijn, R.; Herder, J.; Callaghan, T.; Bjoern, L.O.; Jones, D.G.; Broekman, R.; Blokker, P.; van de Poll, W.H.

    2006-01-01

    The response of tundra plants to enhanced UV-B radiation simulating 15 and 30% ozone depletion was studied at two high arctic sites (Isdammen and Adventdalen, 78 degrees N, Svalbard).The set-up of the UV-B supplementation systems is described, consisting of large and small UV lamp arrays, installed

  5. RadNet (Environmental Radiation Ambient Monitoring System)

    Data.gov (United States)

    U.S. Environmental Protection Agency — RadNet, formerly Environmental Radiation Ambient Monitoring System (ERAMS), is a national network of monitoring stations that regularly collect air, precipitation,...

  6. 外源NO对增补UV-B辐射下兴安落叶松幼苗叶片光合色素和叶绿素荧光特性的影响%Effect of Exogenous Nitric Oxide on Photosynthetic Pigments and Chlorophyll Fluorescence under Enhanced UV-B Radiation in Larix gmelinii

    Institute of Scientific and Technical Information of China (English)

    孟庆焕; 祖元刚; 郭晓瑞; 段喜华

    2013-01-01

    在增强UV-B辐射下,以3年生兴安落叶松幼苗为实验材料,研究了外源NO供体硝普钠(Sodium nitroprusside,SNP)对幼苗的光合色素(Chla、Chlb和Car)和叶绿素荧光参数的影响.方差分析结果表明0.5 mmol·L-1的SNP对增补UV-B胁迫下的兴安落叶松幼苗产生显著影响.0.5 mmol·L-1的SNP能够显著抑制增补UV-B辐射后光合色素、Fv/Fm、φPSⅡ、Fv’/Fm’和qP的明显下降以及Chla/Chlb、Fo和NPQ的升高.表明了外源NO能够减轻UV-B辐射胁迫下兴安落叶松幼苗光合反应中心的生理损伤,从而增强兴安落叶松幼苗对增补UV-B辐射胁迫环境的适应能力.%Under enhanced UV-B radiation,3-year-old seedlings of Larix gmelinii were chose as target to study the impact of exogenous nitric oxide on photosynthetic pigments (Chl a,Chl b and Car) and chlorophyll fluorescence.The results of variance analysis showed 0.5 mmol · L-1 sodium nitroprusside (SNP) ,a NO donor,have significant impact on nursery stocks of L.gmelinii under enhanced UV-B radiation stress.0.5 mmol · L-1 SNP can significantly inhibited the apparent decline in photosynthetic pigments,Fy/Fm,ΦPSⅡ ,Fv'/Fm' and qP,and the obvious increase in chl a/chl b,F0 and NPQ after supplement UV-B radiation.All these results indicated that exogenous nitric oxide could reduce the physical damage of photosynthetic reaction centers in seedlings of L.gmelinii under UV-B radiation stress,and enhancement of environmental adaptability of the seedling to supplementary UV-B radiation stress.

  7. High Mortality of Red Sea Zooplankton under Ambient Solar Radiation

    OpenAIRE

    Al-Aidaroos, Ali M.; El-Sherbiny, Mohsen M. O.; Sathianeson Satheesh; Gopikrishna Mantha; Susana Agustī; Beatriz Carreja; Duarte, Carlos M.

    2014-01-01

    High solar radiation along with extreme transparency leads to high penetration of solar radiation in the Red Sea, potentially harmful to biota inhabiting the upper water column, including zooplankton. Here we show, based on experimental assessments of solar radiation dose-mortality curves on eight common taxa, the mortality of zooplankton in the oligotrophic waters of the Red Sea to increase steeply with ambient levels of solar radiation in the Red Sea. Responses curves linking solar radiatio...

  8. UV-B辐射对8个大豆品种种子萌发率和 幼苗生长的影响%Effects of increased UV-B radiation on seed germination and seedlings growth of eight cultivars of Glycine max

    Institute of Scientific and Technical Information of China (English)

    冯虎元; 徐世健; 安黎哲; 刘志杰; 王勋陵

    2001-01-01

    Eight cultivars of soybean (Glycine max (L.) Merr.) were exposed to visible light (220 μmol.m-2.s-1),three dose of UV-B radiation (5,10,15 μW.cm-2.s-1,respectively) and the dark to investigated the effects of enhanced UV-B radiation on seed germination and seedlings growth.The results indicate that enhanced UV-B irradiation had no effect on the germination of soybean cultivars,maximum germination,however,was influenced by UV-B in some cultivars.In addition,UV-B retarded the time up to their maximum germination.Germination in the dark was higher than visible light and increased ultraviolet-B irradiance .Enhanced UV-B radiation led to root of seedlings stunt and short.Chlorophyll a,chlorophyll b and total chlorophyll concentration were also reduced by enhanced UV-B irratiation while flavonoids were stimulated.These UV-B effect and differences between soybean cultivars would cause far-reaching biological and ecological significance.%在生长房5种(暗处、可见光、低、中、高强度紫外线-B)处理下,研究了8个大豆品种的种子萌发率和萌发后幼苗的生长状况。结果表明,暗处种子萌发率高于自然光和UV-B辐射的种子。UV-B辐射增强对大豆种子的萌发率没有显著影响,仅使部分品种的最大萌发率降低和导致部分品种达到最大萌发率的时间延长。幼苗的生长对增强的UV-B辐射非常敏感。使大部分品种的胚根变短增粗,这可能是植物激素作用的结果。大豆的叶绿素a、叶绿素b和总叶绿素含量明显受到UV-B辐射的抑制。UV-B作用能促进类黄酮在幼苗中的积累,紫外吸收色素的增设有利于提高对UV-B的抵抗力。UV-B辐射的这种效应及大豆品种间的差异在自然情况下会产生深远的生物学和生态学意义

  9. Effects of reduced UV-B radiation on morphological characteristics of flue-cured tobacco and its identical and difference analysis%减弱UV-B辐射对烤烟形态特征影响及其同异分析

    Institute of Scientific and Technical Information of China (English)

    钟楚

    2011-01-01

    Stem height, girth, internode distance and leaf length, width and area of the 7th, 11' and 15' leaves in different reduced UV-B radiation conditions (T,, 75. 74% ; T2, 70. 08% and T3, 30. 39% ) in field were investigated to determine effects of reduced UV-B radiation on morphological characteristics of flue-cured tobacco NC297. Comprehensive characteristics was analyzed with identical and difference analysis (IDA) and compared with grey relation analysis ( GRA). Results showed that reduced UV-B radiation increased stem height and internode distance of NC297 with T2 > T3 >T, , but significantly reduced stem girth with T3. The 7' leaf was affected comparatively larger than the others. Leaf length and area were increased with T2 and T3 as well as leaf width increased significantly with T2. Leaf length of the 11 * leaf was increased with T2 and T3. However, leaf width and leaf area of the 11 leaf and all characteristics of the 15 leaf were not significantly affected by UV-B radiation. Both results of IDA and GRA showed that comprehensive effect of reduced UV-B radiation on morphology of flue-cured tobacco was non-linear. The morphology was more sensitive to UV-B radiation with higher intensity UV-B. Result of IDA was reliable, and the calculation was more simple and convenient than GRA. Therefore, it can be used for comprehensive evaluation of flue-cured tobacco morphology.%为研究UV-B辐射对烤烟形态的影响,分析了大田不同减弱UV-B辐射(T1,75.74%;T2,70.08%;T3,30.39%)条件下烤烟品种NC297株高、茎围、节距和第7、11、15叶位的叶长、叶宽和叶面积的差异.采用同异分析法分析了不同UV-B辐射下NC297的综合形态特征,并与灰色关联度分析法进行了对比.结果表明,减弱UV-B辐射增加了NC297株高和节距,且T2>T3>T1,而T3茎围显著降低.第7叶位受UV-B辐射影响较大,其中叶长和叶面积以T2和T3增加明显,叶宽以T2增加明显,而第11叶位仅T2和T3叶长增加显

  10. Ambient radiation exposure: measurements and effects

    International Nuclear Information System (INIS)

    A brief review of the available literature, data and reports of various radiation exposure and protection studies and various measurements techniques are presented. A linear quadratic model has been given illustrating the validity of radiation hormesis

  11. Ecological Effects on the Aphid Sitobion avenae (Fabricius) Exposed to UV-B Radiation for Several Successive Generations%连续多代UV-B处理对麦长管蚜生态学的影响

    Institute of Scientific and Technical Information of China (English)

    朱国平; 杨杰; 张丽; 赵惠燕

    2012-01-01

    The effects and changing patterns of UV-B on growth, development and reproduction of Sitobion avenae (Fabricius) were evaluated by establishing an age-specific life table of S. avenae exposed to UV-B for eight successive generations. The results revealed that the population degradation existed in the population of S. avenae after being raised for several generations in the experimental condition. Under the UV-B irradiation, the developmental duration (T) increased gradually with the increase of generations, while the intrinsic rate of increase (Rm) , net reproductive rate (R0) > finite increase rate (A) and population number tendency index (I) of S. avenae decreased until the third generations, then stable in the following generations. The developmental duration of the second, the third and the fourth instar nymph from F1 to F5 of S. avenae were delayed, while no significant difference was found in F7 generation. Additionally, under the condition of UV-B, the adult longevity, fecundity (F) and population number tendency index (I) decreased until the F3 generation and then increased or trended to stabilize thereafter. In conclusion, the effects of UV-B would be accumulated in the progeny. As the selective forces in the environment, UV-B inhibited the growth and propagation of S. avenae, however, the adaptation of S. avenae to stress was enhanced with the increase of generations. We also found that, the transform of phenotype from unwinged to winged S. avenae was significant in this study, which was related with that of the ecology parameters.%为评估紫外线UV-B对麦长管蚜Sitobion avenae (Fabricius)生长、发育和繁殖的影响,用中波紫外线(UV-B)连续照射8代麦长管蚜3、4龄若虫,并用特定年龄生命表方法对其后代生态学参数进行分析.结果显示,麦长管蚜在实验室条件下多代饲养,表现出明显的种群退化现象.在UV-B的影响下,随着世代的增加,麦长管蚜的内禀增长率(Rm)、净增值率(R0)

  12. 连续2年UV-B辐射增强对传统水稻品种群体磷、钾累积及异质性特征的影响%Effects of Two-Year Concessional Enhance UV-B Radiation on P and K Accumulation and Heterogeneous Distribution of 2 Traditional Rice Varieties in Yuanyan Terraces

    Institute of Scientific and Technical Information of China (English)

    祖艳群; 刘畅; 何永美; 李元

    2015-01-01

    UV-B radiation, which is one of environmental problem, has influenced ecosystem and human health. UV-B radiation has been paid more and more attention due to its influencing on material cycle. It is important to evaluate the responses of stable agricultural ecosystem to enhanced UV-B radiation, which located in area with high elevation and background UV-B. Field experiments were conducted to understand effects of two-year concessional UV-B radiation (0 and 5.0 kJ·m-2·d-1) on P and K accumulation and heterogeneous distribution of two traditional rice (Oryza sativa)varieties (BJLJ and YLG) in-situ Yuanyan terraces, Yunnan Province. The results showed that (1) Under two-year concessional enhanced UV-B radiation, biomass of leaves, stem, root and grain of two rice varieties decreased by 8.1%~61.3%; (2) Expect for P accumulation of stem of YLG, P contents and accumulation of leaves, stem, root, grain of two rice varieties increased with P accumulation of leaves and grain increased by 39.0%~46.2% and 39.1%~66.7%, respectively; (3) K accumulation of stem and root of two rice varieties increased. Except for total K accumulation of BJLJ in 2012, K accumulation increased by under enhanced UV-B radiation 5.0 kJ·m-2·d-1treatment. Therefore, P and K accumulation of traditional rice varieties increased with enhanced UV-B radiation. The responses of traditional rice varieties to enhance UV-B radiation are assumed on P accumulation in leaves, stem resistance and grain nutrients reserve.%UV-B辐射增强作为全球环境问题之一,UV-B辐射增强对全球物质循环产生的影响受到广泛的关注.为了评估持久稳定农田生态系统营养元素在高海拔和高 UV-B 辐射背景下对 UV-B 辐射的响应,在元阳梯田大田条件下,通过 2 年连续UV-B辐射处理(0和5.0 kJ·m-2·d-1),原位研究低纬度高海拔区稳定持续稻田生态系统中传统水稻(Oryza sativa)品种(月亮谷-YLG和白脚老粳-BJLJ)对P素和K素的群体累积特征及

  13. UV-B Perception and Acclimation in Chlamydomonas reinhardtii.

    Science.gov (United States)

    Tilbrook, Kimberley; Dubois, Marine; Crocco, Carlos D; Yin, Ruohe; Chappuis, Richard; Allorent, Guillaume; Schmid-Siegert, Emanuel; Goldschmidt-Clermont, Michel; Ulm, Roman

    2016-04-01

    Plants perceive UV-B, an intrinsic component of sunlight, via a signaling pathway that is mediated by the photoreceptor UV RESISTANCE LOCUS8 (UVR8) and induces UV-B acclimation. To test whether similar UV-B perception mechanisms exist in the evolutionarily distant green alga Chlamydomonas reinhardtii, we identified Chlamydomonas orthologs of UVR8 and the key signaling factor CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1). Cr-UVR8 shares sequence and structural similarity to Arabidopsis thaliana UVR8, has conserved tryptophan residues for UV-B photoreception, monomerizes upon UV-B exposure, and interacts with Cr-COP1 in a UV-B-dependent manner. Moreover, Cr-UVR8 can interact with At-COP1 and complement the Arabidopsis uvr8 mutant, demonstrating that it is a functional UV-B photoreceptor. Chlamydomonas shows apparent UV-B acclimation in colony survival and photosynthetic efficiency assays. UV-B exposure, at low levels that induce acclimation, led to broad changes in the Chlamydomonas transcriptome, including in genes related to photosynthesis. Impaired UV-B-induced activation in the Cr-COP1 mutant hit1 indicates that UVR8-COP1 signaling induces transcriptome changes in response to UV-B. Also, hit1 mutants are impaired in UV-B acclimation. Chlamydomonas UV-B acclimation preserved the photosystem II core proteins D1 and D2 under UV-B stress, which mitigated UV-B-induced photoinhibition. These findings highlight the early evolution of UVR8 photoreceptor signaling in the green lineage to induce UV-B acclimation and protection. PMID:27020958

  14. Transcriptional profiling of summer wheat, grown under different realistic UV-B irradiation regimes.

    Science.gov (United States)

    Zinser, Christian; Seidlitz, Harald K; Welzl, Gerhard; Sandermann, Heinrich; Heller, Werner; Ernst, Dieter; Rau, Werner

    2007-07-01

    There is limited information on the impact of present-day ultraviolet-B (UV-B) radiation on a reprogramming of gene expression in crops. Summer wheat was cultivated in controlled environmental facilities under simulated realistic climatic conditions. We investigated the effect of different regimes of UV-B radiation on summer wheat (Triticum aestivum L.) cultivars Nandu, Star and Turbo. Until recently, these were most important in Bavaria. Different cultivars of crops often show great differences in their sensitivity towards UV-B radiation. To identify genes that might be involved in UV-B defence mechanisms, we first analyzed selected genes known to be involved in plant defence mechanisms. RNA gel blot analysis of RNA isolated from the flag leaf of 84-day-old plants showed differences in transcript levels among the cultivars. Flag leaves are known to be important for grain development, which was completed at 84 days post-anthesis. Catalase 2 (Cat2) transcripts were elevated by increased UV irradiation in all cultivars with highest levels in cv. Nandu. Pathogenesis-related protein 1 (PR1) transcripts were elevated only in cv. Star. A minor influence on transcripts for phenylalanine ammonia-lyase (PAL) was observed in all three cultivars. This indicates different levels of acclimation to UV-B radiation in the wheat cultivars studied. To analyze these responses in more detail, UV-B-exposed flag leaves of 84-day-old wheat (cv. Nandu) were pooled to isolate cDNAs of induced genes by suppression-subtractive hybridization (SSH). Among the initially isolated cDNA clones, 13 were verified by RNA gel blot analysis showing an up-regulation at elevated levels of UV-B radiation. Functional classification revealed genes encoding proteins associated with protein assembly, chaperonins, programmed cell death and signal transduction. We also studied growth, flowering time, ear development and yield as more typical agricultural parameters. Plant growth of young plants was reduced at

  15. Surviving but not thriving: inconsistent responses of zooxanthellate jellyfish polyps to ocean warming and future UV-B scenarios.

    Science.gov (United States)

    Klein, Shannon G; Pitt, Kylie A; Carroll, Anthony R

    2016-01-01

    Complex changes to UV radiation at the Earth's surface are occurring concurrently with ocean warming. Despite few empirical tests, jellyfish are hypothesised to be increasing in some parts of the world because they are robust to environmental stressors. Here we examine the effects of UV-B and ocean warming projections on zooxanthellate jellyfish polyps. We exposed Cassiopea sp. polyps to three levels of UV-B (future-low (1.43 Wm(2)), current (1.60 Wm(2)), future-high (1.77 Wm(2))) and two levels of temperature (current-day (25 °C) and future (28 °C)) over 6 weeks. The intensity of UV-B was varied throughout the day to mimic diel variation in UV-B irradiance. Polyp survival, asexual reproduction and YII were measured. In the current and future-high UV-B treatments, more polyps were produced in 25 °C than 28 °C. This pattern, however, was reversed under future-low UV-B conditions, where more polyps were produced at 28 °C. YII was highest under current summer conditions and future conditions of low UV-B and increased temperature. YII, however, was reduced under high UV-B conditions but was further reduced with warming. Our results suggest that although Cassiopea polyps may survive elevated UV-B and warming conditions, they are unlikely to thrive. If, however, UV-B radiation decreases then ocean warming may facilitate increases in Cassiopea populations. PMID:27374028

  16. 达乌里胡枝子抗氧化防御系统对干旱及增强UV-B辐射的动态响应%Dynamic Responses of Antioxidative Defense System of Lespedeza davurica to Drought and Enhanced UV-B Radiation

    Institute of Scientific and Technical Information of China (English)

    赵洁; 杜润峰; 王龙飞; 王钰莹; 郝文芳

    2013-01-01

    以达乌里胡枝子(Lespedeza davurica)为研究对象,通过对照、中度干旱以及干旱与增强UV-B辐射复合处理,对其超氧阴离子(O2-)、丙二醛(MDA)和抗氧化剂含量及抗氧化酶活性的动态变化进行研究,探讨其抗氧化能力及膜脂过氧化的动态响应.结果表明:与单因子干旱胁迫相比,复合胁迫使超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性降低,抗坏血酸过氧化物酶(APX)及过氧化物酶(POD)活性升高,其中低强度UV-B辐射与干旱复合胁迫使SOD活性极显著低于单因子干旱胁迫下的(P<0.01),POD活性随UV-B辐射强度增加而降低,APX和CAT活性随UV-B辐射强度增加而增加.与单因子干旱胁迫相比,复合胁迫使抗坏血酸(AsA)含量增加,且随UV-B辐射强度的增加先增加后降低;使叶绿素(Chl)和类胡萝卜素(Car)含量降低,随UV-B辐射强度增加而降低.低强度UV-B辐射与干旱复合胁迫前6d花青素含量极显著高于对照(P<0.01).复合胁迫前期,MDA和O2-含量均比单因子干旱胁迫的低,后期则不同.隶属函数综合评价得出,中度干旱以及复合胁迫均能提高达乌里胡枝子的抗氧化能力,且与干旱胁迫相比,低强度UV B辐射与干旱复合胁迫下其抗氧化能力较高,而高强度UV-B辐射与干旱复合胁迫下则较低.%The effects of drought and enhanced UV-B radiation on the antioxidant defense system and membrane lipid peroxidation in Lespedeza davurica were investigated. Compared with the single-stress of drought, the co-stresses of drought and enhanced UV-B radiation decreased the activities of superoxide dis-mutase (SOD) and catalase (CAT) , and increased the activities of ascorbate peroxidase (APX) and peroxi-dase (POD). SOD activity under the co-stresses of drought and low UV-B radiation intensity was significantly lower than that under the single-stress of drought. With the increase of UV-B radiation intensity under co-stresses, POD activity decreased

  17. UV-B辐射引起的绿豆幼苗叶片Rubisco量降低与H2O2含量升高有关%Reduction of Rubisco Amount by UV-B Radiation Is Related to Increased H2O2 Content in Leaves of Mung Bean Seedlings

    Institute of Scientific and Technical Information of China (English)

    贺军民; 佘小平; 孟朝妮; 赵文明

    2004-01-01

    To understand the role of H2O2 in the damaging effect of UV-B radiation on ribulose- 1,5-bisphosphate carboxylase/oxygenase (Rubisco)content, the time courses of changes in Rubisco and H2O2 contents under UV-B treatment were measured in the primary leaves of two mung bean cultivars (Phaseolus raditus L. cv. Zhonglu-1 and Qindou-20). A 0.4 W/m2 UV-B treatment caused a drop of the former to about 1/3 and a 30%-40%rise in H2O2 content in a week in both cultivars but with Qindou-20 showing stronger responses. Such higher rate of increase in proteolytic activity under UV-B treatment implies that UV-B lowers Rubisco by activating proteolytic enzymes which hydrolizes Rubisco. Scavenging of H2O2 by exogenously added ascorbic acid (ASA) significantly inhibited the UV-B-induced decrease in Rubisco amount and increases in H2O2 level and proteolytic activity. It is shown that H2O2 participates in the UV-B-induced reduction of Rubisco amount. It is suggested that H2O2 stimulates the degradation of Rubisco by activation of proteolytic systems.%为了探讨UV-B辐射引起的Rubisco含量降低的可能机制,研究了两个绿豆品种(秦豆-20和中绿-1)幼苗在UV-B辐射下叶片Rubisco含量、蛋白水解酶活性和H2O2含量的变化.结果表明:UV-B辐射显著加速了两个绿豆品种幼苗叶片H2O2含量和蛋白水解酶活性上升,使Rubiscco含量下降.秦豆-20品种在UV-B辐射下H2O2含量和蛋白水解酶活性的上升程度明显大于中绿-1,相应其Rubisco含量的下降程度也大于中绿-1.抗坏血酸处理能明显降低UV-B辐射下两品种幼苗叶片H2O2含量,同时明显抑制蛋白水解酶活性的上升及Rubisco含量的下降.结果说明UV-B辐射诱导Rubisco含量的降低可能通过提高H2O2水平从而加强蛋白水解酶系统的活化而加速了Rubisco的降解.

  18. UV-B辐射胁迫对水稻叶绿素荧光动力学的影响%Effects of enhanced UV-B radiation stress on kinetics of chlorophyll fluorescence in rice Coryza sativa L

    Institute of Scientific and Technical Information of China (English)

    林文雄; 吴杏春; 梁义元; 陈芳育; 郭玉春

    2002-01-01

    研究结果表明,增强的紫外线-B(UV-B,280~320nm)辐射会导致水稻植株矮化4.71%~16.59%、叶面积变小、干物质生产量减少11.79%~60.57%.究其原因主要是叶片光合作用色素叶绿素a、叶绿素b和类胡萝卜素含量的降低和叶绿素a荧光动力学参数的改变,光合系统Ⅱ受到破坏,光合作用能力下降、生长发育受阻.

  19. 不同生育期美丽风毛菊PSⅡ光化学效率和色素含量对UV-B辐射的响应%Response of PS Ⅱ photochemistry efficiency and photosynthetic pigments during exposure of alpine plants Saussurea superba to natural UV-B radiation

    Institute of Scientific and Technical Information of China (English)

    丁伟; 尚艳霞; 师瑞; 师生波

    2012-01-01

    A UV-B-exclusion study was performed in alpine Kobresia humilis meadow during plants growing season. The PS II photochemistry efficiency, photosynthetic pigments and UV-B-absorbing compounds were measured on native alpine plant Saussurea superba. 1) The 3 min dark adapted quantum efficiency of PS II photochemistry, Fv/Fm, showed an increasing trend after a short-term removal UV-B radiation from natural sunlight in all measurements. These means there were photo-inactivation and/or photo-damage of photosynthesis occurred in PS II reaction center. 2)There were same tendency in PS II photochemistry efficiency ΦPSII and photochemical quenching qP for all measurements during plants growing season; The ΦPSII and qP were increased and NPQ decreased after removal UV-B treatment, which means that there was an increasing in PS II photochemistry efficiency and a decreasing in non-photochemical quenching and current solar UV-B intensity can impair photosynthetic function. 3) The reduction of photosynthetic pigments contents were mainly caused by the reducing of leaf thickness and relative increase of photosynthetic pigments contents in amb UV-B treatment a specious phenomenon. In summary, strong solar UV-B radiation in Qinghai-Tibet region has a potential negative influence on photosynthetic physiology process in S. superba. UV-B-absorbing compounds were not influenced during the short-term removal of UV-B radiation, mainly due to strong stabilization of these compounds existed in the epidermal layer of the alpine plant S. superba and can provide effective defense against the natural solar UV-B intensity.%以高山植物美丽风毛菊为材料,在矮嵩草草甸植物群落生长季的不同月份,采用短期滤除太阳辐射光谱中UV-B成分的方法,研究了UV-R辐射对PSⅡ光化学效率、光合色素和紫外吸收物质的影响.结果表明,1)与对照相比,low UV-B处理时3 min暗适应的PSⅡ最大光化学量子效率Fv/Fm呈升高的趋势,说明UV-B辐

  20. Raised UV-B Stress at the Time of the end-Permian Biosphere Crisis

    Science.gov (United States)

    Visscher, H.; Brinkhuis, H.; Kuerschner, W.; Looy, C.; Van Konijnenburg - Van Cittert, J.

    2001-12-01

    It is likely that the Phanerozoic biosphere has been exposed to recurrent episodes of elevated UV-B radiation caused by ozone depletion events. Natural phenomena that have the potential to disrupt the stratospheric ozone balance include asteroid or comet impacts and large-scale volcanism. However, while UV-B exposure has long been known to be damaging to life, no distinctive UV-B effects have so far been detected in the fossil record of terrestrial and aquatic organisms. Notably land plants display a wide variety of biochemical and morphological responses to enhanced UV-B exposure. Adverse effects of UV-B stress on photosynthesis, growth and development of plants are largely due to altered gene action. Progressive increase in mutation rates indicates that UV-B enhancement can generate genomic instability of plant populations. Among fossil remains of land plants, only successive assemblages of dispersed spores and pollen may provide the sample size and stratigraphic spacing needed to recognize morphological traits that could indicate enhanced mutation. In spores and pollen of recent plants, mutational effects can be reflected morphologically by abnormal variation in overall shape and size, disorganized wall structure and/or the presence of permanent tetrads in which individual microspores have failed to separate from one another during sporogenesis. On the basis of spore/pollen records from Europe, North America, Asia and Africa, we document the worldwide proliferation of dispersed tetrads of microspores of heterosporous lycopsids that occurred in conjunction with the dramatic end-Permian biosphere crisis. This conspicuous `tetrad event' may reflect an episode of raised UV-B stress, resulting from ozone depletion induced by outgassing of volatile halocarbons at the time of emplacement of voluminous doleritic intrusives in organic-rich Paleozoic deposits in Siberia.

  1. UV-B optical thickness observations of the atmosphere

    Science.gov (United States)

    Kirchhoff, V. W. J. H.; Silva, A. A.; Costa, C. A.; Leme, N. Paes; PavãO, H. G.; Zaratti, F.

    2001-02-01

    The optical thickness of the atmosphere, τ, was deduced from measurements of narrowband direct solar UV-B radiation. A measurement campaign was organized to obtain the radiation at three different sites, during the month of August 1999, using the same methods and instruments, in order to deduce the atmospheric optical thickness in the spectral UV-B range (280-320 nm). The three observation sites were chosen to cover a wide range of measurement conditions; located near the tropical Atlantic Ocean (Natal, 5.8°S, 35.2°W), on the Andes mountains (La Paz, 16.5°S, 68.1°W), and in the biomass burning area of central Brazil (Campo Grande, 19.2°S, 54.3°W). The UV-B measurements were made with a Brewer spectrophotometer at each site. Since the instrument measures atmospheric ozone and SO2 simultaneously, it is possible, from the total atmospheric optical thickness τ, to deduce the aerosol optical thickness τaerosol. The results have been combined in different ways to compare with satellite data, showing good performance. Time variations as short as about 10 min can be seen. On clear days the time variations are relatively small, as expected. On the other hand, for the biomass burning site, for conditions of mixed air masses (the instrument is not looking directly at plumes) one can see very large variations in τ in relatively short time intervals, for example, for one case, from 3.5 to 7.0 in about 30 min. Absolute values for τ at Natal and La Paz were near 2.0 and at Campo Grande, between 2.5 and 3.0, but with occasional highs of about 4.5. For τaerosol, Natal and La Paz had values between 0.0 and 0.4, whereas Campo Grande had most values near 0.4, with occasional highs near 1.0, 1.2, and 2.2.

  2. Development of an innovative peat lipstick based on the UV-B protective effect of humic substances

    Directory of Open Access Journals (Sweden)

    R. Klöcking

    2013-04-01

    Full Text Available Humic acids (HA are known for their antiviral and UV-B protecting effects, and are considered promising as ingredients for a UV-protective lipstick which is being developed to minimise or even prevent recurrences of UV- induced herpes. In this study, the UV/Vis spectra of three natural HA and three synthetic HA-like substances are analysed to determine the appropriateness of their UV-absorbing characteristics for the product under development. The contribution of a matrix component (castor oil to the total UV absorption of the lipstick is also assessed. The results confirm the expected high UV-B absorption of the individual test substances, but reveal considerable differences in the UV-A wavelength range. Castor oil absorbs only UV-B radiation; and when mixed with HA it enhances total absorption in the UV-B range, but reduces it in the UV-A range. This is probably due to molecular interactions between castor oil and HA. Preliminary results from cultures of human U937 cells assayed for survival 24 hours after exposure to UV-B radiation show that both HA and castor oil exert a significant concentration-dependent UV-B protective filter effect similar to that of the UV-B absorbing reference substance p-aminobenzoic acid (PABA.

  3. Enhanced expression and differential inducibility of soybean chalcone synthase genes by supplemental UV-B in dark-grown seedlings

    International Nuclear Information System (INIS)

    By developing gene-specific RT-PCR and using filters to allow transmission down to 290 nm (UV-B+) or blocking all radiation below 320 nm (UV-B(-)), the effect of UV-B+ and UV-B- light on expression of each of the presently known seven members of soybean chalcone synthase (CHS) gene family in dark-grown seedlings was analyzed. Dark expression was detectable already in 18 h dark-germinating embryos, with progressive increases on successive days, suggesting that chs belongs to a class of genes expressed very early during germination, and that the expression at this stage is either constitutive or induced by non-light-dependent factors present in the seed or made available following imbibition. Exposure of 18 h dark-germinating embryos to UV-B- or to UV-B+ light did not lead to an increase in chs signal. However, the 24 h dark-germinating embryos showed a distinct effect of UV-B+, interestingly coinciding with the stage when the head of seedlings was in the process of being pushed up above ground by stem elongation, suggesting the possibility of a developmental switch modulating the appearance of UV-B response. The response to UV-B- was most prominent in chs1 and almost silent in chs2, while the up-regulation by UV-B+ was most prominent in chs5 and chs6 and much less so in chs2. Interestingly, chs2 was noted to be the only member of the Gmchs gene family devoid of H-box, raising the possibility that the H-box may be a good indicator of the photo-inducibility of a chs gene. (author)

  4. Relationship of Indirect Effects of UV-B Radiation on Stomatal Movement of Vicia faba Leaves with Nitric Oxide and Hydrogen Peroxide%UV-B辐射对蚕豆叶片气孔运动的间接效应与NO和H2O2有关

    Institute of Scientific and Technical Information of China (English)

    徐华; 贺军民; 黄辰; 佘小平

    2006-01-01

    0.2 W·m-2的UV-B辐射不仅能诱导整体蚕豆叶片气孔导度和开度的显著降低,而且能明显降低蚕豆叶肉光合活性,但该强度的UV-B辐射却不能明显影响离体表皮条的气孔开度.说明0.2 W·m-2的UV-B主要通过间接途径调控了蚕豆叶片气孔运动.借助药理学试验和激光扫描共聚焦显微镜技术,进一步对该间接效应过程中是否有NO和H2O2的参与进行了探讨.结果显示:NO专一性清除剂cPTIO和一氧化氮合酶(NOS)抑制剂L-NAME均能有效地抑制UV-B辐射诱导的叶片气孔关闭和保卫细胞内源NO水平的升高;H2O2清除剂抗坏血酸(ASC)和过氧化氢酶(CAT)也能有效地逆转UV-B辐射诱导的气孔关闭和保卫细胞内源H2O2含量的升高.另外,外源NO或H2O2处理也能有效地诱导叶片气孔关闭.结果说明0.2 W·m-2的UV-B辐射对蚕豆叶片气孔关闭的间接诱导与NO和H2O2有关.%0.2 W · m-2 UV-B radiation could induce Vicia faba leaves to not only significantly reduce their stomatal conductance and aperture as a whole but also significantly decrease photosynthetic activity of their leaf mesophyll,but this radiation could not exert significant influence on the stomatal aperture of excised epidermis strips. This indicated that 0. 2 W · m-2 UV-B ratiation adjusted the stomatal movement of V. faba leaves mainly in indirect ways. Whether NO and H2O2 were concerned with the adjustment in indirect ways was further explored by pharmaceutical experiment and laser-scanning confocal microscopy. The results showed that cPTIO,a scavenger specific to No,and L-NAME,NO-synthase inhibitor,both effectively inhibited the closedown of the leaf stomata and the increase of endogenous NO in the guard cells,which were induced by UV-B radiation;ascorbic acid ,a H2O2 in the guard cells ,which were induced by UV-B radiation. In addition,exogenous NO or H2O2 could effectively induce the closedown of the leaf stomata. It was indicated that the indirect

  5. 大田增强UV-B辐射对元阳梯田地方水稻茎秆性状和倒伏指数的影响%Effects of enhanced UV-B radiation on culm charateristics and lodging index of two local rice varieties in Yuanyang terraces under field condition

    Institute of Scientific and Technical Information of China (English)

    何永美; 湛方栋; 祖艳群; 徐渭渭; 李元

    2015-01-01

    Two local rice varieties (Baijiaolaojing and Yuelianggu) were cultivated in situ in Yuanyang terraces,China,in 2012 and 2013 to investigate the effect of enhanced UV-B radiation condition (0,2.5,5.0 and 7.5 kJ · m-2) on internode characteristics including length,culm diameter,culm wall thickness from the first to the fourth internode,as well as the lodging index.The results showed that UV-B radiation had no significant influence on internode length and culm,but significantly reduced the culm wall thickness,with that of the fourth internode region decreased by 11.6% to 19.6% under 7.5 kJ · m-2 UV-B radiation.The enhanced UV-B radiation increased the lodging index of rice varieties,making them more prone to lodging.The fourth internode had the highest lodging index which was higher than the lodging critical value (200).The decrease in culm wall thickness due to the enhanced UV-B radiation could be responsible for the increasing lodging risk of rice varieties grown in Yuanyang terraces.%大田原位种植元阳梯田2个地方水稻品种——白脚老粳和月亮谷,研究2年不同强度(0、2.5、5.0和7.5 kJ·m-2)UV-B辐射对水稻穗下第1至第4节的茎秆性状(节间长、茎秆粗和茎壁厚)和倒伏指数的影响.结果表明:增强UV-B辐射对水稻茎秆的节间长和茎秆粗没有显著影响,但导致茎壁厚度显著减小,其中,7.5 kJ·m-2 UV-B辐射对水稻穗下第4节茎秆茎壁厚度的影响较大,降幅为11.6%~19.6%;增强UV-B辐射导致水稻茎秆的倒伏指数增加,增大水稻倒伏的风险,水稻穗下第4节茎秆倒伏指数最大,并大于倒伏临界值(200);水稻穗下第4节、第3节和第2节茎秆的倒伏指数与茎壁厚度呈显著负相关.表明增强UV-B辐射显著减小元阳梯田水稻茎秆的茎壁厚是增加其倒伏风险的主要原因.

  6. 短时间不同剂量UV-B辐射处理对冬小麦幼苗生理指标的影响%Influences of Different UV-B Radiation Treatments in Short Time on Some Physiological Characteristics of Winter Wheat Seedlings

    Institute of Scientific and Technical Information of China (English)

    张文会; 王明卓; 苗秀莲; 张玉霞; 李宝娟

    2009-01-01

    [Objective] studying the influences of different UV-B radiation treatments in short time on some physiological characteristics of winter wheat seedlings was to provide reference for the mechanism of plant response to ultraviolet irradiation in short time. [Method] The winter wheat taken as materials were treated with 15 and 30 μW/cm2 UV-B radiation, then the physiological indexes such as pigment content and photosynthetic rate were determined. [Results] The UV-B treatment caused the declines of chlorophyll content, soluble protein content and water content of leaves, besides, dose-effect was existed. The decline of 30 μW/cm2 treatment was bigger than that of 15 μW/cm2 treatment. The influences of UV-B radiation on carotenoid content and anthocyanidin content were similar; the change trends were declined firstly then increased. The UV-B treatment with two doses restrained the electron transport of PSⅡ, particularly; the inhibitory effect was biggest after treated 2 h, and then this effect was declined in 4, 6 and 8 h, so the dose-effect was existed. The UV-B radiation with two doses restricted photosynthetic rate and the inhibitory effect increased with the increase of treatment time. The high dose treatment caused huge damage to membrane system, while the result of low dose treatment was not obvious. [Conclusion] UV-B radiation treatment had dose-effect on winter wheat seedlings in short time and the influence of high dose was bigger than that of low dose. With the increase of treatment time, the damage was alleviated; besides, the result was not similar to that of UV-B radiation in long time.%[目的]研究短时间不同剂量UV-B辐射对冬小麦幼苗叶片生理指标的影响,为进一步研究植物应答短时间紫外线照射的机理提供参考.[方法]以冬小麦为试验材料,采用15和30 μW/cm2的UV-B照射强度对冬小麦幼苗进行短时间照射处理.测定指标包括:①反射光谱值.用Unispec光谱仪测定反射光谱,并计

  7. UV B-Induced Vertical Migrations of Cyanobacteria in a Microbial Mat.

    Science.gov (United States)

    Bebout, B M; Garcia-Pichel, F

    1995-12-01

    Exposure to moderate doses of UV B (0.35 to 0.79 W m(sup-2) s(sup-1) or 0.98 to 2.2 (mu)mol of photons m(sup-2) s(sup-1) at 310 nm) caused the surface layers of microbial mats from Solar Lake, Sinai, Egypt, to become visibly lighter green. Concurrent with the color change were rapid and dramatic reductions in gross photosynthesis and in the resultant high porewater oxygen concentrations in the surface layers of the mats. The depths at which both maximum gross photosynthesis and maximum oxygen concentrations occurred were displaced downward. In contrast, gross photosynthesis in the deeper layers of the mats increased in response to UV B incident upon the surface. The cessation of exposure to UV B partially reversed all of these changes. Taken together, these responses suggest that photoautotrophic members of the mat community, most likely the dominant cyanobacterium Microcoleus chthonoplastes, were migrating in response to the added UV B. The migration phenomenon was also observed in response to increases in visible radiation and UV A, but UV B was ca. 100-fold more effective than visible radiation and ca. 20-fold more effective than UV A in provoking the response. Migrating microorganisms within this mat are apparently able to sense UV B directly and respond behaviorally to limit their exposure to UV. Because of strong vertical gradients of light and dissolved substances in microbial mats, the migration and the resultant vertical redistribution of photosynthetic activity have important consequences for both the photobiology of the cyanobacteria and the net primary productivity of the mat ecosystem.

  8. UV B-induced vertical migrations of cyanobacteria in a microbial mat

    International Nuclear Information System (INIS)

    Exposure to moderate doses of UV B (0.35 to 0.79 W m-2 s-1 or 0.98 to 2.2 μmol of photons m-2 s-1 at 310 nm) caused the surface layers of microbial mats from Solar Lake, Sinai, Egypt, to become visibly lighter green. Concurrent with the color change were rapid and dramatic reductions in gross photosynthesis and in the resultant high porewater oxygen concentrations in the surface layers of the mats. The depths at which both maximum gross photosynthesis and maximum oxygen concentrations occurred were displaced downward. In contrast, gross photosynthesis in the deeper layers of the mats increased in response to UV B incident upon the surface. The cessation of exposure to UV B partially reversed all of these changes. Taken together, these responses suggest that photoautotrophic members of the mat community, most likely the dominant cyanobacterium Microcoleus chthonoplastes, were migrating in response to the added UV B. The migration phenomenon was also observed in response to increases in visible radiation and UV A, but UV B was ca. 100-fold more effective than visible radiation and ca. 20-fold more effective than UV A in provoking the response. Migrating microorganisms within this mat are apparently able to sense UV B directly and respond behaviorally to limit their exposure to UV. Because of strong vertical gradients of light and dissolved substances in microbial mats, the migration and the resultant vertical redistribution of photosynthetic activity have important consequences for both the photobiology of the cyanobacteria and the net primary productivity of the mat ecosystem

  9. 水稻对UV-B辐射增强的抗性遗传及其生理生化特性研究%Genetics of resistance of Oryza sativa to increased UV-B radiation and its physiobiochemical characteristics

    Institute of Scientific and Technical Information of China (English)

    林文雄; 梁义元; 金吉雄

    1999-01-01

    本研究结果表明紫外线B(UV-B,280~330nm)能严重影响水稻秧苗生长发育,从而引起植株矮化,叶片干枯,叶绿素含量降低,单株干物质减少甚至死亡.不同水稻基因型对紫外线的反应存在明显差异.在3个供试品种(HR、M63、Hr)中,HR最抗UV-B危害.遗传分析表明水稻抗UV-B的性状为数量遗传性状且受多对隐性基因控制,生化分析表明水稻秧苗经UV-B处理后,在0~3d内,随着时间推移,秧苗保护酶活性明显增强,之后,保护酶活性逐惭下降,MDA含量相应增加.抗UV-B品种HR比感UV-B品种Hr保护酶活性一直较高,膜质过氧化程度较低,反映了保护酶对抵抗UV-B危害的重要作用.

  10. UV—B增强下6-BA、GA3对油桃光合和抗氧化酶活性的影响%Effects of 6-BA and GA3 on photosynthesis and antioxidase activity of nectarine under enhanced UV-B radiation

    Institute of Scientific and Technical Information of China (English)

    张良英; 牛歆雨; 刘林

    2012-01-01

    [Objective] The study was to find out the regulation metabolism of plant growth regulators on photosynthesis of nectarine under enhanced UV-B radiation. [Method] The effects of 6-BA and GA3 on photosynthesis and antioxidase activity of nectarine were investigated. [Result] The results showed that Pn value decreased and chlorophyll a content increased in TL treatment (supplemental UV'B 15 μW·cm^(-2)). However, both Pn value and chlorophyll a content decreased significantly in TH treatment(supplemental UV-B 30 μW· cm^(-2)). Under enhanced UV-B radiation, foliar spray of 50 mg" L-1 GA3 and 6-BA improved Pn, the content of chlorophyll a and b, compared with TH. 6-BA increased SOD and POD activity in leaves under enhanced UV-B, but reduced MDA content. Flavoniod content increased in TH +6-BA treatment, but it was not significantly different from that of CK. Flavoniod content of TH +GA3 treatment increased significantly. However, MDA content and antioxidase activity had no significant change. [Conclusion] It is suggested that the increase of net photosynthetic rate in TH +6-BA treatment under en- hanced UV-B radiation may attribute to the enhance of SOD and POD activity.%【目的】为探讨uv—B增强下植物生长调节剂对油桃光合作用的调控,【方法】以‘中油桃8号’为试材,研究了叶面喷施6一BA和GA,对UV—B增强下油桃光合特性和抗氧化酶活性的影响。【结果l结果表明,补充15μW·cm^(-2)的UV—B辐射后,油桃的净光合速率下降,叶绿素a含量增加;补充30μW·cm^(-2)之的UV-B辐射,净光合速率和叶绿素a含量受到明显抑制,叶绿素b略有下降。喷施50mg·L^(-1)6-BA和GA,可有效提高UV—B增强下叶片的Pn和叶绿素a、b含量。50mg·L^(-1)6-BA处理14d后,UV—B增强下叶片的SOD、POD活性明显上升,MDA含量显著下降,类黄酮含量与对照无显著差异;而GA3处理则提高了叶片的类

  11. Probing behaviors of Sitobion avenae (Hemiptera: Aphididae on enhanced UV-B irradiated plants

    Directory of Open Access Journals (Sweden)

    Hu Zu-Qing

    2013-01-01

    Full Text Available UV-B induced changes in plants can influence sap-feeding insects through mechanisms that have not been studied. Herein the grain aphid, Sitobion avenae (Fabricius (Hemiptera: Aphididae, was monitored on barley plants under the treatments of control [0 kJ/ (m2.d], ambient UV-B [60 kJ/ (m2.d], and enhanced UV-B [120 kJ/ (m2.d] irradiation. Electrical penetration graph (EPG techniques were used to record aphid probing behaviors. Enhanced UV-B irradiated plants negatively affected probing behaviors of S. avenae compared with control plants. In particular, phloem factors that could diminish sieve element acceptance appeared to be involved, as reflected by smaller number of phloem phase, shorter phloem ingestion, and fewer aphids reaching the sustained phloem ingestion phase (E2>10min. On the other hand, factors from leaf surface, epidermis, and mesophyll cannot be excluded, as reflected by higher number of non-probing, longer non-probing and pathway phase, and later the time to first probe.

  12. Response of radiation monitors for ambient dose equivalent, H*(10)

    International Nuclear Information System (INIS)

    Radiation monitors are used all over the world to evaluate if places with presence of ionising radiation present safe conditions for people. Radiation monitors should be tested according to international or national standards in order to be qualified for use. This work describes a methodology and procedures to evaluate the energy and angular responses of any radiation monitor for ambient dose equivalent, H*(10), according to the recommendations of ISO and IEC standards. The methodology and the procedures were applied to the Monitor Inteligente de Radiacao MIR 7026, developed by the Instituto em Engenharia Nuclear (IEN), to evaluate and to adjust its response for H*(10), characterizing it as an ambient dose equivalent meter. The tests were performed at the Laboratorio Nacional de Metrologia das Radiacoes Ionizantes (LNMRI), at Instituto de Radioprotecao e Dosimetria (IRD), and results showed that the Monitor Inteligente de Radiacao MIR 7026 can be used as an EI*(10) meter, in accordance to the IEC 60846 standard requirements. The overall estimated uncertainty for the determination of the MIR 7026 response, in all radiation qualities used in this work, was 4,5 % to a 95 % confidence limit. (author)

  13. Effects of UV-B exclusion on photosynthetic physiology in alpine plant Saussurea superba%滤除自然光中UV-B辐射成分对高山植物美丽风毛菊光合生理的影响

    Institute of Scientific and Technical Information of China (English)

    师生波; 尚艳霞; 朱鹏锦; 张德罡

    2011-01-01

    采用滤除自然光谱中UV-B辐射成分的方法,探讨了高山植物美丽风毛菊(Saussurea superba)光合机构对青藏高原强UV-B辐射的响应和适应特性.结果表明,强太阳光中的UV-B成分能引起净光合速率的降低.连续16天不同天气下的观测表明,滤除UV-B处理时3 min暗适应的光化学量子效率有升高的趋势;晴天下稳态光化学效率的分析也显示滤除UV-B处理的实际光化学量子效率和光化学猝灭系数有升高趋势,意味着自然光中的UV-B成分可限制美丽风毛菊叶片PSII反应中心的激发能捕获效率.PSII有效光化学量子效率的增加和非光化学猝灭系数的降低进一步表明,UV-B辐射能导致有效光化学效率的降低和非光化学能量耗散的增加.由上可知,自然强UV-B辐射是限制美丽风毛菊叶片光合作用的一个因素.滤除UV-B辐射处理对光合色素含量的影响较小,无论以叶面积还是叶鲜重为基础的滤除UV-B处理仅有微弱的增加趋势,说明强UV-B辐射具有加速光合色素的光氧化进程,促进细胞成熟和叶片衰亡的潜在作用.同样UV-B吸收物质的含量也几乎没有变化,表明强太阳辐射环境下生活的高山植物美丽风毛菊叶表皮层中已具有较多的紫外线屏蔽物质,足以抵御目前环境中强太阳UV-B辐射可能引起的伤害,较少受UV-B辐射波动的影响.%Aims In the Qinghai-Tibet area, high levels of UV-B radiation reach the earth's surface as part of strong solar radiation.It is therefore important to examine the response and adaptation of native alpine plants to strong UV-B radiation.Our objective was to determine the physiological response of the photosynthetic apparatus to current ambient UV-B intensity.Methods UV-B-exclusion experiments were conducted on a field site with UV-B-excluding and UV-B-transmining filters.The two filters transmitted similar levels of photosynthetically active radiation, and there were no differences

  14. O3浓度升高和UV-B辐射增强对大豆叶片抗氧化酶活性及POD同工酶的影响%Combined Effects of Elevated O3 Concentration and UV-B Radiation on Anti-Oxidative Enzymes Activities and POD Enzymes Isozymes of Soybean

    Institute of Scientific and Technical Information of China (English)

    刘轶鸥; 王岩; 刘波; 杨兴; 赵天宏

    2013-01-01

    During the last several decades, significant reductions in the concentrations of stratospheric ozone( O3) have been reported. The decrease of ozone concentration causes an increment of ultraviolet-B radiation to earth surface. The objective of this experiment is to reveal the toxicological mechanism under elevated ozone concentration and UV-B radiation singly or in combination on plant anti-oxidation enzymes activities and POD isoenzyme. Open-top chambers ( OTCs) were utilized to investigate change of anti-oxidation enzymes activities and POD isoenzyme band in soybean( Glycine max) leaves under elevated ozone concentration and UV-B radiation singly or in combination treatment. The results of anti-oxidation enzymes activities indicated that either O3 treatment or UV-B treatment induced a decrease on SOD,POD and CAT,and in the combined stress,anti-oxidation enzymes activities had intensified this trend to a certain degree. The result of POD isozyme band showed that a new band appeared under O3 treatment in branching stage and two new bands appeared in flowering stage and podding stage compared of branching stage,and the shade of color of POD isoenzyme bands was lighter compared to CK treatment. It was suggested that in all growth period,POD isoenzyme activity was inhibited under combined stress.%以大豆品种铁丰29为材料,利用开顶式气室(OTCs)研究了O3浓度升高和UV-B辐射增强单独胁迫及复合胁迫下大豆叶片抗氧化酶(SOD、POD和CAT)活性及POD同工酶谱带的变化.结果表明:O3处理大豆叶片SOD、CAT和POD活性均低于对照;UV处理下,大豆叶片SOD、CAT、POD活性也均低于对照,但基本高于O3处理;O3及UV复合处理下,加剧了SOD、CAT、POD活性的减弱.对POD同工酶研究发现,在分枝期,O3处理产生Ⅰ条新谱带,开花期和结荚期均比分枝期多2条谱带,并且受胁迫处理的POD酶谱带与对照相比颜色较浅,说明在整个生育期,胁迫处理下的大豆叶片POD同工酶活性受到抑制.

  15. Non-invasive measurements of leaf epidermal transmittance of UV radiation using chlorophyll fluorescence: field and laboratory studies

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, P.W. [Southwest Texas State Univ.. Dept. of Biology, San Marcos, TX (United States); Searles, P.S.; Ryel, R.J.; Caldwell, M.M. [Utah State Univ., Dept. of Rangeland Resources and the Ecology Center, Logan, UT (United States); Ballare, C.L. [IFEVA, Univ. de Buenos Aires, Dept. de Ecologia, Facultad de Agronomia, Buenos Aires, (Argentina)

    2000-07-01

    Ratios of chlorophyll fluorescence induced by ultraviolet (UV) and bluegreen (BG) radiation [F(UV)/F(BG)] were determined with a Xe-PAM fluorometer to test the utility of this technique as a means of non-intrusively assessing changes in the pigmentation and optical properties of leaves exposed to varying UV exposures under laboratory and field conditions. For plants of Vicia faba and Brassica campestris, grown under controlled-environmental conditions, F(UV-B)/F(BG) was negatively correlated with whole-leaf UV-B-absorbing pigment concentrations. Fluorescence ratios of V.faba were similar to, and positively correlated with (r{sup 2} = 0.77 [UV-B]; 0.85 [UV-A]), direct measurements of epidermal transmittance made with an integrating sphere. Leaves of 2 of 4 cultivars of field-grown Glycine max exposed to near-ambient solar UV-B at a mid-latitude site (Buenos Aires, Argentina, 34 degrees S) showed significantly lower abaxial F(UV-B)/F(BG) values (i.e., lower UV-B epidermal transmittance) than those exposed to attenuated UV-B, but solar UV-B reduction had a minimal effect on F(UV-B)/F(BG) in plants growing at a high-latitude site (Tierra del Fuego, Argentina, 55 degrees S). Similarly, the exotic Taraxacum officinale did not show significant changes in F(UV-B)/F(BG) when exposed to very high supplemental UV-B (biologically effective UV-B = 14-15 kJ m{sup -2} day{sup -1}) in the field in Tierra del Fuego, whereas a native species, Gunnera magellanica, showed significant increases in F(UV-B)/F(BG) relative to those receiving ambient UV-B. These anomalous fluorescence changes were associated with increases in BG-absorbing pigments (anthocyanins), but not UV-B-absorbing pigments. These results indicate that non-invasive estimates of epidermal transmittance of UV radiation using chlorophyll fluorescence can detect changes in pigmentation and leaf optical properties induced by UV-B radiation under both field and laboratory conditions. However, this technique may be of limited

  16. Is parietin a UV-B or a blue-light screening pigment in the lichen Xanthoria parietina?

    Science.gov (United States)

    Gausla, Yngvar; Ustvedt, Elin Margrete

    2003-04-01

    Xanthoria parietina is a widespread lichen coloured by the orange cortical pigment parietin (= physcion). We studied the pigment content in 60 thalli sampled in 4 habitats along a sun-shade gradient from evergreen boreal forests through open deciduous stands to sea cliffs. The significant positive regression between contents of parietin per unit area and site factors (reflecting the openness of the canopy relative to an open sky) across sampled habitats suggested a photoprotective role of parietin at UV-B and/or blue wavelengths, the two absorbance maxima of parietin. UV-B susceptibility of X. parietina, measured as permanent reductions in photosystem II, decreased highly significantly with increasing parietin content per thallus area. However, as much as three-fold greater UV-B irradiances than ambient daily summer maxima, maintained continuosly for 240 h were required to cause UV-B damage even in thalli of shaded habitats. Since a previous study has documented a high PAR susceptibility of parietin-deficient X. parietina in the absence of UV-B, there are reasons to believe that the blue light screening of parietin is functionally more important than the UV-B screening. A strong positive relationship between parietin content per unit area and reflectance at 500 nm allows the parietin content in X. parietina thalli to be assessed non-destructively by reflectance measurements.

  17. The interactive effects of UV-B and insecticide exposure on tadpole survival, growth and development

    Science.gov (United States)

    Bridges, C.M.; Boone, M.D.

    2003-01-01

    Because declines within amphibian populations can seldom be attributed to a single cause, it is important to focus on multiple stressors, both natural and anthropogenic. Variables such as UV-B radiation and chemical contamination can interact with one another in ways that might not be predicted from single-factor studies. We exposed southern leopard frog (Rana sphenocephala) tadpoles to the insecticide carbaryl and varying intensities of UV-B radiation in artificial ponds and examined their effects on survival, size at metamorphosis, and the duration of the larval period. Tadpole survival to metamorphosis was positively influenced by UV-B intensity. Tadpoles in ponds exposed to carbaryl contained over three times more algae and yielded larger metamorphs than control ponds. Although previous laboratory studies have indicated carbaryl becomes more toxic in the presence of UV-B, we did not find such an effect, perhaps because of the protection afforded by dissolved organic carbon within the ponds. Our research emphasizes the importance of conducting field studies to more accurately predict what occurs under a natural setting. Published by Elsevier Science Ltd.

  18. Effects of temperature on UV-B-induced DNA damage and photorepair in Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    LI Shao-shan; WANG Yan; BJ(O)RN Lars Olof

    2004-01-01

    DNA damage in the form of cyclobutane pyrimidine dimers(CPDs) and (6-4) photoproducts(6-4PPs) induced by UV-B radiation in Arabidopsis thaliana at different temperatures was investigated using ELISA with specific monoclonal antibodies. CPDs and 6-4PPs increased during 3 h UV-B exposure, but further exposure led to decreases. Contrary to the commonly accepted view that DNA damage induced by UV-B radiation is temperature-independent because of its photochemical nature, we found UV-B-induction of CPDs and 6-4PPs in Arabidopsis to be slower at a Iow than at a high temperature. Photorepair of CPDs at 24℃ was much faster than that at 0℃ and 12℃,with 50% CPDs removal during 1 h exposure to white light. Photorepair of 6-4PPs at 12℃ was very slow as compared with that at 24℃,and almost no removal of 6-4PPs was detected after 4 h exposure to white light at 0℃. There was evidence to suggest that temperaturedependent DNA damage and photorepair could have important ecological implications.

  19. Arabidopsis STO/BBX24 negatively regulates UV-B signaling by interacting with COP1 and repressing HY5 transcriptional activity

    Institute of Scientific and Technical Information of China (English)

    Lei Jiang; Yan Wang; Qian-Feng Li; Lars Olof Bj(o)rn; Jun-Xian He; Shao-Shan Li

    2012-01-01

    UV-B (280-315 nm) is an integral part of solar radiation and can act either as a stress inducer or as a developmental signal.In recent years,increasing attention has been paid to the Iow-fluence UV-B-induced photomorphogenic response and several key players in this response have been identified,which include UVR8 (a UV-B-specific photoreceptor),COPI (a WD40-repeat-containing RING finger protein),HY5 (a basic zipper transcription factor),and RUP1/2 (two UVR8-interacting proteins).Here we report that Arabidopsis SALT TOLERANCE (STO/BBX24),a known regulator for light signaling in plants,defines a new signaling component in UV-B-mediated photomorphogenesis.The bbx24 mutant is hypersensitive to UV-B radiation and becomes extremely dwarfed under UV-B treatment.By contrast,BBX24 overexpression transgenic lines respond much more weakly to UV-B than the bbx24 and wild-type plants.BBX24 expression is UV-B-inducible and its accumulation under UV-B requires COP1.Co-immunoprecipitation experiments indicate that BBX24 interacts with COP1 in planta upon UV-B illumination.Moreover,BBX24 interacts with HY5 and acts antagonistically with HY5 in UV-B-induced inhibition of hypocotyl elongation.Furthermore,BBX24 attenuates UV-B-induced HY5 accumulation and suppresses its transcription-activation activity.Taken together,our results reveal a previously uncharacterized function of the light-regulated BBX24 in UV-B responses and demonstrate that BBX24 functions as a negative regulator of photomorphogenic UV-B responses by interacting with both COP1 and HY5.The UV-B-inducible expression pattern and its suppression of HY5 activity suggest that BBX24 could be a new component of the feedback regulatory module of UV-B signaling in plants.

  20. The impact of enhanced ultraviolet-B radiation on litter quality and decomposition processes in Vaccinium leaves from the Subarctic

    International Nuclear Information System (INIS)

    The aim of this study was to investigate how UV-B radiation will affect 1) the quality of plant litter grown under different UV-B levels in the Subarctic and 2) decomposition under different UV-B levels. The deciduous dwarf shrubs Vaccinium uliginosum and V. myrtillus grew under ambient and enhanced UV-B (corresponding to 15% ozone depletion) in a natural heath ecosystem in the Subarctic. After two growing seasons senesced leaves were collected and decomposed in a 2 × 2 factorial experiment under both laboratory conditions for 62 d (V. uliginosum: no UV-B and 10 kJ m-2 d-1 UV- BBE) and under field conditions for twelve months (V. myrtillus: ambient and enhanced UV-B corresponding 15% ozone depletion). Additionally, colonization and growth of decomposing fungi were studied on leaves decomposed without and with UV-B in the laboratory. The enhanced UV-B during growth changed the litter quality (decrease in α-cellulose, increase in tannins). Subsequently the microbial respiration was decreased. This and the decreased cellulose/lignin ratio may have led to the lower relative mass loss due to treatments as detected both after 62 d decomposition in the laboratory and after twelve months decomposition in the field. The UV-B during decomposition decreased the proportion of lignin in the plant residues, which is possibly due to photodegradation by UV-B. Total microbial respiration decreased, indicating the decomposers' sensitivity to UV-B. In general, the litter decomposing under UV-B was less colonized by fungal decomposers. Mucor hiemalis and Truncatella truncata were significantly more abundant in the control, indicating sensitivity to UV-B radiation, while Penicillium brevicompactum was equally abundant in the UV-B and control. There is strong indication of a change in decomposer fungal community structure due to UV-B. Just one of the three fungal species common on the control litter was dominant on leaves decomposed under UV-B. (author)

  1. Factors affecting UV-B-induced changes in Arabidopsis thaliana L. gene expression: The role of development, protective pigments and the chloroplast signal

    International Nuclear Information System (INIS)

    Gene expression is known to change in response to UV-B radiation. In this paper, we have investigated three factors in Arabidopsis leaves that are likely to influence these changes: development, protective pigments and the 'chloroplast signal'. During late leaf development the major change in pigment composition, after exposure to UV-B radiation, is an increase in UV-absorbing pigments. Chl and Chl a/b ratio do not change substantially. Similarly Chl fluorescence is not altered. In contrast, RNA transcripts of photosynthetic proteins are reduced more in older leaves than in young leaves. To determine the role of flavonoids in UV-B protection, plants of Arabidopsis mutant tt-5, which have reduced flavonoids and sinapic esters, were exposed to UV-B and RNA transcript levels determined. The tt-mutants were more sensitive to UV-B radiation than wild-type. To examine the role of the chloroplast signal in regulating UV-B induced changes in gene expression, Arabidopsis gun mutants (genome uncoupled) have been used. The results show that UV-B-induced down-regulation still takes place in gun mutants and strongly suggests that the chloroplast signal is not required. Overall, this study clearly demonstrates that UV-B-induced changes in gene expression are influenced by both developmental and cellular factors but not chloroplastic factors

  2. UVR8 mediates UV-B-induced Arabidopsis defense responses against Botrytis cinerea by controlling sinapate accumulation.

    Science.gov (United States)

    Demkura, Patricia V; Ballaré, Carlos L

    2012-05-01

    Light is emerging as a central regulator of plant immune responses against herbivores and pathogens. Solar UV-B radiation plays an important role as a positive modulator of plant defense. However, since UV-B photons can interact with a wide spectrum of molecular targets in plant tissues, the mechanisms that mediate their effects on plant defense have remained elusive. Here, we show that ecologically meaningful doses of UV-B radiation increase Arabidopsis resistance to the necrotrophic fungus Botrytis cinerea and that this effect is mediated by the photoreceptor UVR8. The UV-B effect on plant resistance was conserved in mutants impaired in jasmonate (JA) signaling (jar1-1 and P35S:JAZ10.4) or metabolism of tryptophan-derived defense compounds (pen2-1, pad3-1, pen2 pad3), suggesting that neither regulation of the JA pathway nor changes in levels of indolic glucosinolates (iGS) or camalexin are involved in this response. UV-B radiation, acting through UVR8, increased the levels of flavonoids and sinapates in leaf tissue. The UV-B effect on pathogen resistance was still detectable in tt4-1, a mutant deficient in chalcone synthase and therefore impaired in the synthesis of flavonoids, but was absent in fah1-7, a mutant deficient in ferulic acid 5-hydroxylase, which is essential for sinapate biosynthesis. Collectively, these results indicate that UVR8 plays an important role in mediating the effects of UV-B radiation on pathogen resistance by controlling the expression of the sinapate biosynthetic pathway. PMID:22447155

  3. UVR8 Mediates UV-B-Induced Arabidopsis Defense Responses against Botrytis cinerea by Controlling Sinapate Accumulation

    Institute of Scientific and Technical Information of China (English)

    Patricia V. Demkura; Carlos L. Ballaré

    2012-01-01

    Light is emerging as a central regulator of plant immune responses against herbivores and pathogens.Solar UV-B radiation plays an important role as a positive modulator of plant defense.However,since UV-B photons can interact with a wide spectrum of molecular targets in plant tissues,the mechanisms that mediate their effects on plant defense have remained elusive.Here,we show that ecologically meaningful doses of UV-B radiation increase Arabidopsis resistance to the necrotrophic fungus Botrytis cinerea and that this effect is mediated by the photoreceptor UVR8.The UV-B effect on plant resistance was conserved in mutants impaired in jasmonate (JA) signaling (jar1-1 and P35S:JAZ10.4) or metabolism of tryptophan-derived defense compounds (pen2-1,pad3-1,pen2 pad3),suggesting that neither regulation of the JA pathway nor changes in levels of indolic glucosinolates (iGS) or camalexin are involved in this response.UV-B radiation,acting through UVR8,increased the levels of flavonoids and sinapates in leaf tissue.The UV-B effect on pathogen resistance was still detectable in tt4-f,a mutant deficient in chalcone synthase and therefore impaired in the synthesis of flavonoids,but was absent in fah1-7,a mutant deficient in ferulic acid 5-hydroxylase,which is essential for sinapate biosynthesis.Collectively,these results indicate that UVR8 plays an important role in mediating the effects of UV-B radiation on pathogen resistance by controlling the expression of the sinapate biosynthetic pathway.

  4. INFLUENCE OF UV-B RADIATION ON THE INTERSPECIFIC COMPETITION BETWEEN AMPHIDINIUM CARTERAE AND ISOCHRYSIS GALBANA%UV-B辐射对强壮前沟藻(Amphidinium carterae)和等鞭金藻(Isochrysis galbana)种间竞争的影响

    Institute of Scientific and Technical Information of China (English)

    谢志浩; 俞泓伶; 曹鲁妍

    2011-01-01

    In this paper, the effects of UV-B radiation on interspecific competition between Amphidinium carterae and Isochrysis galbana were studied using the co-culture method. The results showed that: in single culture experiments, with increased inoculums, both species entered the exponential growth phase and the plateau phase faster, and the maximum cell density reduced. In the mixed culture experiments, L galbana dominated in the competition with A. carterae in the A : 1 = 1 : 4 and the A : I = 1 : 1 treatments. In contrast, only under the A : I = 4 : 1 inoculation ratio did A. carterae exhibit inhibition to the growth of L galbana. UV-B irradiation effectively influenced the interspecific growth interaction of these two species. With increased UV-B irradiation, the competitive dominance of L galbana decreased in the A : I = 1 : 4 treatment and in some cases, A. carterae became relatively more competitive in the A : I = 4 : 1 treatment.%采用共培养的方法,研究了UV-B辐射对不同起始密度强壮前沟藻和等鞭金藻种间竞争的影响。结果表明,在单养时,随着起始密度的增加,2种微藻在生长过程中进入指数生长期和平台期的时间逐渐缩短,所达到的最大种群密度都依次降低。在混养时,当接种比例为A∶I=1∶4和A∶I=1∶1时,等鞭金藻在种间竞争中占有优势;当接种比例为A∶I=4∶1时,强壮前沟藻占有优势。UV-B辐射对两种微藻的种间竞争存在明显的影响。接种比例为A∶I=1∶4时,随着UV-B辐射时间的延长,等鞭金藻对强壮前沟藻的竞争优势逐渐降低,接种比例为A∶I=4∶1时,强壮前沟藻的竞争优势有所加强。

  5. Regulation of the expression of NADP-malic enzyme by UV-B, red and far-red light in maize seedlings

    Directory of Open Access Journals (Sweden)

    P. Casati

    1999-10-01

    Full Text Available The induction of nicotinamide adenine dinucleotide phosphate-malic enzyme (NADP-ME in etiolated maize (Zea mays seedlings by UV-B and UV-A radiation, and different levels of photosynthetically active radiation (PAR, 400-700 nm was investigated by measuring changes in activity, protein quantity and RNA levels as a function of intensity and duration of exposure to the different radiations. Under low levels of PAR, exposure to UV-B radiation but not UV-A radiation for 6 to 24 h caused a marked increase in the enzyme levels similar to that observed under high PAR in the absence of UV-B. UV-B treatment of green leaves following a 12-h dark period also caused an increase in NADP-ME expression. Exposure to UV-B radiation for only 5 min resulted in a rapid increase of the enzyme, followed by a more gradual rise with longer exposure up to 6 h. Low levels of red light for 5 min or 6 h were also effective in inducing NADP-ME activity equivalent to that obtained with UV-B radiation. A 5-min exposure to far-red light following UV-B or red light treatment reversed the induction of NADP-ME, and this effect could be eliminated by further treatment with UV-B or red light. These results indicate that physiological levels of UV-B radiation can have a positive effect on the induction of this photosynthetic enzyme. The reducing power and pyruvate generated by the activity of NADP-ME may be used for respiration, in cellular repair processes and as substrates for fatty acid synthesis required for membrane repair.

  6. UV-B affects photosynthesis, ROS production and motility of the freshwater flagellate, Euglena agilis Carter

    Energy Technology Data Exchange (ETDEWEB)

    Kottuparambil, Sreejith [Institute of Green Environmental Research Center, University of Incheon, Incheon, 406 840 (Korea, Republic of); Shin, Woongghi [Department of Biology, Chungnam University, Daejeon, 306 764 (Korea, Republic of); Brown, Murray T. [School of Marine Science and Engineering, Plymouth University, Drake Circus, Plymouth PL4 8AA (United Kingdom); Han, Taejun, E-mail: hanalgae@hanmail.net [Institute of Green Environmental Research Center, University of Incheon, Incheon, 406 840 (Korea, Republic of); Department of Marine Science, University of Incheon, Incheon, 406 840 (Korea, Republic of)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer We proposed a hypothesis for the UV-B protective/adaptive mechanism in Euglena agilis. After moderate levels of UV-B radiation, ROS plays a signaling role to shut down photosynthetic system for protection against harmful UV radiation. Black-Right-Pointing-Pointer E. agilis exposed to excessive UV appears to become animal-like, investing all its stored energy into movement rather than into sustaining its photosynthetic machinery. Black-Right-Pointing-Pointer This adaptation allows E. agilis to avoid harmful UV and seek a safe place where the organism may regain its photosynthetic capacity for survival. - Abstract: The effects of ultraviolet B (UV-B; 295-320 nm) radiation on certain vital physiological (photosynthesis), biochemical (production of reactive oxygen species - ROS) and behavioral (motility and orientation) characteristics were investigated in the unicellular photoautotroph, Euglena agilis Carter. The photosynthetic performance of E. agilis was recorded after exposure of between 15 and 60 min followed by a period of recovery lasting 6-24 h under dim light (5-10 {mu}mol photons m{sup -2} s{sup -1}). The maximum quantum yield of PS II (F{sub v}/F{sub m}) was reduced to 65% and 14% of initial values immediately following 15 and 30 min UV-B exposure, but recovered to 100 and 86% of the initials, respectively. Values of rETR{sub max} in E. agilis exposed to 15 min UV-B were similar to those of the initials, but a 30 min UV exposure resulted in 75% reduction of rETR{sub max} with only a 43% recovery as compared with the initial after 24 h recovery. After a 60 min UV-B exposure, there were no Chl a fluorescence signals, and hence no F{sub v}/F{sub m} or rETR{sub max}. A UV dose-dependent increase in DCFH-DA fluorescence was found in E. agilis cells, reflecting an increase in ROS production. After exposures to UV-B for between 15 and 60 min, the percentages of motile cells in the population decreased to 76, 39 and 15

  7. Ambient temperature cadmium zinc telluride radiation detector and amplifier circuit

    International Nuclear Information System (INIS)

    A low noise, low power consumption, compact, ambient temperature signal amplifier for a Cadmium Zinc Telluride (CZT) radiation detector is disclosed. The amplifier can be used within a larger system (e.g., including a multi-channel analyzer) to allow isotopic analysis of radionuclides in the field. In one embodiment, the circuit stages of the low power, low noise amplifier are constructed using integrated circuit (IC) amplifiers , rather than discrete components, and include a very low noise, high gain, high bandwidth dual part preamplification stage, an amplification stage, and an filter stage. The low noise, low power consumption, compact, ambient temperature amplifier enables the CZT detector to achieve both the efficiency required to determine the presence of radionuclides and the resolution necessary to perform isotopic analysis to perform nuclear material identification. The present low noise, low power, compact, ambient temperature amplifier enables a CZT detector to achieve resolution of less than 3% full width at half maximum at 122 keV for a Cobalt-57 isotope source. By using IC circuits and using only a single 12 volt supply and ground, the novel amplifier provides significant power savings and is well suited for prolonged portable in-field use and does not require heavy, bulky power supply components. 9 figs

  8. The effects of ultraviolet-B radiation on freshwater invertebrates: Experiments with a solar simulator

    Science.gov (United States)

    Hurtubise, R.D.; Havel, J.E.; Little, E.E.

    1998-01-01

    There is concern that decreases in stratospheric ozone will lead to hazardous levels of ultraviolet-B (UV-B) radiation at the Earth's surface. In clear water, UV-B may penetrate to significant depths. The purpose of the current study was to compare the sensitivity of freshwater invertebrates to UV-B. We used a solar simulator, calibrated to match local ambient solar radiation, to expose five species of freshwater invertebrates to enhanced levels of UV-B radiation. UV-B measurements in a eutrophic pond revealed that 10% of the irradiance penetrated to 30-cm depth and 1% to 57-cm depth. The irradiance at the upper 5-20 cm was comparable to levels used in the simulator. Median lethal dose (LD50) values were determined for the cladocerans Ceriodaphnia reticulata, Scapholeberis kingii (two induced color morphs), and Daphnia magna; the ostracod Cyprinotus incongruens; and the amphipod Hyalella azteca. Among the species, 96-h LD50 estimates were quite variable, ranging from 4.2 to 84.0 ??W cm-2. These estimates indicated S. kingii to be highly sensitive and H. azteca, C. reticulata, and D. magna to be moderately sensitive, whereas the ostracod C. incongruens was very tolerant to UV-B radiation. Overall, this study suggests that, in shallow ponds without physical refuges, UV-B radiation would have the strongest effects upon cladocerans and amphipods occurring in the water column, whereas ostracods would be better protected.

  9. Regulation of plant MSH2 and MSH6 genes in the UV-B-induced DNA damage response.

    Science.gov (United States)

    Lario, Luciana D; Ramirez-Parra, Elena; Gutierrez, Crisanto; Casati, Paula; Spampinato, Claudia P

    2011-05-01

    Deleterious effects of UV-B radiation on DNA include the formation of cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone photoproducts (6-4PPs). These lesions must be repaired to maintain the integrity of DNA and provide genetic stability. Of the several repair systems involved in the recognition and removal of UV-B-induced lesions in DNA, the focus in the present study was on the mismatch repair system (MMR). The contribution of MutSα (MSH2-MSH6) to UV-induced DNA lesion repair and cell cycle regulation was investigated. MSH2 and MSH6 genes in Arabidopsis and maize are up-regulated by UV-B, indicating that MMR may have a role in UV-B-induced DNA damage responses. Analysis of promoter sequences identified MSH6 as a target of the E2F transcription factors. Using electrophoretic mobility shift assays, MSH6 was experimentally validated as an E2F target gene, suggesting an interaction between MMR genes and the cell cycle control. Mutations in MSH2 or MSH6 caused an increased accumulation of CPDs relative to wild-type plants. In addition, msh2 mutant plants showed a different expression pattern of cell cycle marker genes after the UV-B treatment when compared with wild-type plants. Taken together, these data provide evidence that plant MutSα is involved in a UV-B-induced DNA damage response pathway.

  10. UV-B Exposure Affects the Biosynthesis of Microcystin in Toxic Microcystis aeruginosa Cells and Its Degradation in the Extracellular Space

    Directory of Open Access Journals (Sweden)

    Zhen Yang

    2015-10-01

    Full Text Available Microcystins (MCs are cyclic hepatotoxic heptapeptides produced by cyanobacteria that can be toxic to aquatic and terrestrial organisms. MC synthesis and degradation are thought to be influenced by several different physical and environmental parameters. In this study, the effects of different intensities of UV-B radiation on MC biosynthesis in Microcystis cells and on its extracellular degradation were investigated by mRNA analysis and degradation experiments. Exposure to UV-B at intensities of 1.02 and 1.45 W/m2 not only remarkably inhibited the growth of Microcystis, but also led to a decrease in the MC concentration. In addition, mcyD transcription was decreased under the same UV-B intensities. These results demonstrated that the effects of UV-B exposure on the biosynthesis of MCs in Microcystis cells could be attributed to the regulation of mcy gene transcription. Moreover, the MC concentration was decreased significantly after exposure to different intensities of UV-B radiation. Of the three MC variants (MC-LR, -RR and -YR, L, R and Y are abbreviations of leucine, arginine and tyrosine, MC-LR and MC-YR were sensitive to UV-B radiation, whereas MC-RR was not. In summary, our results showed that UV-B radiation had a negative effect on MC production in Microcystis cells and MC persistence in the extracellular space.

  11. UV-B辐射增强对喜树叶片色素含量和形态结构的影响%Effects of Enhanced UV-B Radiation on Leaf Morphology and Structure and Pigment Contents of Camptotheca acuminata

    Institute of Scientific and Technical Information of China (English)

    王海霞; 刘文哲

    2011-01-01

    Effects of enhanced UV-B radiation (5.0 μW/cm2) on leaf morphology and structure and the contents of photosynthetic pigment and flavonoids in Camptotheca acuminata were investigated in pots experiment. The results showed as follows: (1)The contents of chlorophyll and flavonoids, the ratio of chlorophyll a to chlorophyll b (Chla/Chlb) increased in earlier stage and decreased in later stage under enhanced UV-B radiation compared with which growing under natural light, while carotenoids content increased constantly. (2)The leaf shape asymmetry occurred because of skewing, the photosynthetic pigments distribution in leaves were uneven, the adaxial epidermis was thickened, the chloroplast structure was distorted. (3)Further studies with scanning electron microscope (SEM) observation revealed that the number of epidermal hairs and glandular trichomes increased, glandular trichomes turned shorter and wider, stomatal apparatus in abaxial epidermis were coverd by waxy and aperture decreased. Therefore, the author considered that the UV-B radiation treatment could start the defense system of Camptotheca acuminata seedling, but finally it still could do great harm to the membrane system, membrane lipid peroxidation appeared.%笔者通过盆栽试验,以自然辐射为对照,研究人工增强UV-B辐射下(5.0μW/cm2)喜树叶片中光合色素、类黄酮化合物含量及叶片形态结构的变化.试验结果表明:(1)UV-B辐射增强导致喜树叶片总叶绿素含量、叶绿素a与叶绿素b的比值(Chla/Chlb)及类黄酮类化合物含量上升,并随后呈下降趋势,而类胡萝卜素含量持续升高;(2)UV-B辐射增强导致叶形呈不对称状,色素分布异常,并伴有上表皮增厚、栅栏组织细胞增多、叶绿体扭曲的变化;(3)UV-B辐射增强使喜树叶片上表皮蜡质层增厚,表皮毛和腺毛数量增多,腺毛变短而粗;下表皮气孔被蜡质覆盖,开度变小.因此,增强UV-B辐射处理后,喜树幼苗体内的防御系统

  12. Ecophysiological strategies in response to UV-B radiation stress in cultures of temperate microalgae isolated from the Pacific coast of South America Estrategias ecofisiológicas en respuesta a la radiación ultravioleta-B en cultivos de microalgas templadas aisladas de la costa sudamericana del Pacífico

    Directory of Open Access Journals (Sweden)

    VIVIAN MONTECINO

    2001-06-01

    Full Text Available Marine microalgae exposed to ultraviolet radiation (UV have complex adaptive responses provided by a series of protection and repair mechanisms. Interspecific differences in UV sensibility could result in differential selection of the more tolerant species, having consequences for the structure of phytoplankton assemblages. The relative importance of protection and photorepair mechanisms of microalgal cells exposed to potential UV-B stress was studied in monocultures with different taxonomic, ecological and size characteristics obtained from the Chilean coast. Differences in photosynthesis and growth rates were predicted, since the ability to effectively acclimate to UV is not universal between microalgal species. The dinoflagellate Alexandrium catenella Whedon et Kofoid Balech, the diatom Phaeodactylum tricornutum Bohlin, the chrysophyte Aureococcus sp. and the cyanobacterium Spirulina subsalsa Oersted were acclimated during exponential cell growth under PAR + UV-A radiation (365 nm, 140-240 kJ m-2 d-1 and thereafter exposed 2 h d-1 to high and low UV-B radiation (312 nm, maximum 3.1 kJ m-2 d-1 at the center of the 16 h light period. Measured parameters were growth rates (µ, in vivo spectral absorption, cellular fluorescence capacity, pigment concentration, photosynthesis and photoreactivation during three cycles in controls and treatment samples. Growth rates diminished less than 35 % in Phaeodactylum and Aureococcus compared to 80-100 % decrease in Alexandrium and Spirulina. In these two last species, a significant increase in UV absorbing substances was observed, probably related to the presence of mycosporine-like aminoacids (MAAs and scytonemin, respectively, and also lower photoreactivation efficiency compared to Phaeodactylum and Aureococcus. The analysis of photosynthetic performance under different PAR/UV-A ratios for Alexandrium and Phaeodactylum, could also explain the differences in µ. These results suggest that in time, species

  13. Nitrate limitation and ocean acidification interact with UV-B to reduce photosynthetic performance in the diatom Phaeodactylum tricornutum

    Directory of Open Access Journals (Sweden)

    W. Li

    2014-12-01

    Full Text Available It has been proposed that ocean acidification (OA will interact with other environmental factors to influence the overall impact of global change on biological systems. Accordingly we investigated the influence of nitrogen limitation and OA on the physiology of diatoms by growing the diatom Phaeodactylum tricornutum Bohlin under elevated (1000 μatm, HC or ambient (390 μatm, LC levels of CO2 with replete (110 μmol L-1, HN or reduced (10 μmol L-1, LN levels of NO3- and subjecting the cells to solar radiation with or without UV irradiance to determine their susceptibility to UV radiation (280–400 nm. Our results indicate that OA and UVB induced significantly higher inhibition of both the photosynthetic rate and quantum yield under LN than under HN conditions. UVA or/and UVB increased the cells' non-photochemical quenching (NPQ regardless of the CO2 levels. Under LN and OA conditions, activity of superoxide dismutase and catalase activities were enhanced, along with the highest sensitivity to UVB and the lowest ratio of repair to damage of PSII. HC-grown cells showed a faster recovery rate of yield under HN but not under LN conditions. The finding that nitrate limitation and ocean acidification interact with UV-B to reduce photosynthetic performance of the diatom P. tricornutum implies that ocean primary production and the marine biological C pump will be affected by the OA under multiple stressors.

  14. Association of amphibians with attenuation of ultraviolet-b radiation in montane ponds

    Science.gov (United States)

    Adams, M.J.; Schindler, D.E.; Bury, B.R.

    2001-01-01

    Ambient ultraviolet-b (UV-B) radiation (280-320 nm) has increased at north-temperate latitudes in the last two decades. UV-B can be detrimental to amphibians, and amphibians have shown declines in some areas during this same period. We documented the distribution of amphibians and salmonids in 42 remote, subalpine and alpine ponds in Olympic National Park, Washington, United States. We inferred relative exposure of amphibian habitats to UV-B by estimating the transmission of 305- and 320-nm radiation in pond water. We found breeding Ambystoma gracile, A. macrodactylum and Rana cascadae at 33%, 31%, and 45% of the study sites, respectively. Most R. cascadae bred in fishless shallow ponds with relatively low transmission of UV-B. The relationship with UV-B exposure remained marginally significant even after the presence of fish was included in the model. At 50 cm water depth, there was a 55% reduction in incident 305-nm radiation at sites where breeding populations of R. cascadae were detected compared to other sites. We did not detect associations between UV-B transmission and A. gracile or A. macrodactylum. Our field surveys do not provide evidence for decline of R. cascadae in Olympic National Park as has been documented in Northern California, but are consistent with the hypothesis that the spatial distribution of R. cascadae breeding sites is influenced by exposure to UV-B. Substrate or pond depth could also be related to the distribution of R. cascadae in Olympic National Park.

  15. UV-B inhibition of hypocotyl growth in etiolated Arabidopsis thaliana seedlings is a consequence of cell cycle arrest initiated by photodimer accumulation.

    Science.gov (United States)

    Biever, Jessica J; Brinkman, Doug; Gardner, Gary

    2014-06-01

    Ultraviolet (UV) radiation is an important constituent of sunlight that determines plant morphology and growth. It induces photomorphogenic responses but also causes damage to DNA. Arabidopsis mutants of the endonucleases that function in nucleotide excision repair, xpf-3 and uvr1-1, showed hypersensitivity to UV-B (280-320nm) in terms of inhibition of hypocotyl growth. SOG1 is a transcription factor that functions in the DNA damage signalling response after γ-irradiation. xpf mutants that carry the sog1-1 mutation showed hypocotyl growth inhibition after UV-B irradiation similar to the wild type. A DNA replication inhibitor, hydroxyurea (HU), also inhibited hypocotyl growth in etiolated seedlings, but xpf-3 was not hypersensitive to HU. UV-B irradiation induced accumulation of the G2/M-specific cell cycle reporter construct CYCB1;1-GUS in wild-type Arabidopsis seedlings that was consistent with the expected accumulation of photodimers and coincided with the time course of hypocotyl growth inhibition after UV-B treatment. Etiolated mutants of UVR8, a recently described UV-B photoreceptor gene, irradiated with UV-B showed inhibition of hypocotyl growth that was not different from that of the wild type, but they lacked UV-B-specific expression of chalcone synthase (CHS), as expected from previous reports. CHS expression after UV-B irradiation was not different in xpf-3 compared with the wild type, nor was it altered after HU treatment. These results suggest that hypocotyl growth inhibition by UV-B light in etiolated Arabidopsis seedlings, a photomorphogenic response, is dictated by signals originating from UV-B absorption by DNA that lead to cell cycle arrest. This process occurs distinct from UVR8 and its signalling pathway responsible for CHS induction.

  16. Ambient ultraviolet radiation in the Arctic reduces root biomass and alters microbial community composition but has no effects on microbial biomass

    DEFF Research Database (Denmark)

    Rinnan, R.; Keinänen, M.M.; Kasurinen, A.;

    2005-01-01

    that microbial community composition was altered by UV reduction. Although the UV responses were slight considering the large dose difference between the treatments (from near-ambient to up to 90% UV-B reduction), we cannot rule out the possibility that the recovery of ozone layer would change the below...

  17. 增强UV-B辐射对水稻叶绿素荧光特性的影响%Influence of Enhanced UV-B Radiation on Chlorophyll Fluorescence Characteristics of Rice

    Institute of Scientific and Technical Information of China (English)

    乔媛; 殷红; 李虎; 杨振兴; 高敏

    2014-01-01

    以沈农265水稻为试材,自然光为对照,研究了2种增强紫外辐射处理下(分别增加5%和10%),水稻不同生育时期光合色素含量和叶绿素荧光动力学参数的变化特征。研究结果显示,两处理下的叶绿素含量在拔节期减少最多,叶绿素a分别下降13.87%和23.30%,叶绿素b分别下降10.76%和17.70%;而类胡萝卜素含量均有所增加,其中抽穗期增幅最大,分别比对照增加了21.55%和31.02%。2种处理下的PSⅡ原初光能转换效率( Fv/Fm )在灌浆期下降最多,分别比对照下降了4.4%和7.83%;PSⅡ潜在活性(Fv/Fo)也比对照降低了9.02%和17.03%;实际量子产量(ΦPSⅡ)在抽穗期降幅较大,但处理间差异不显著(P<0.05);2种处理下的光化学荧光淬灭系数(qP)均有所降低,且降幅随生育进程逐渐减小;2种处理下的非光化学荧光淬灭( NPQ)在各生育时期的变化截然相反,分别比对照升高和降低。%It was used to investigate the contents of photosynthetic pigment and the characteristics of chloro-phyll fluorescence kinetics parameters in the different growth stages of rice ( Shennong 265 ) at different treatments (UV radiation intensity increased by 5% and 10% respectively),compared with natural lighting. Results showed that the contents of chlorophyll-a and chlorophyll-b were diminished significantly in the jointing stage. The content of chlorophyll-a was diminished by 13. 87% and 23. 30% respectively. The content of chlorophyll-b was diminished by 10. 76% and 17. 70% respectively. The contents of carotenoids were increased by 21. 55% and 31. 02% respec-tively,especially in the heading stage. The intrinsic photochemical efficiency (Fv/Fm) of two treatments was dimin-ished by 4. 4% and 7. 83% respectively in the filling stage,and the potential activities (Fv/Fo) were diminished by 9. 02% and 17. 03% respectively. Decreasing amplitude of effective quantum yield (ΦPSⅡ) in the heading stage was

  18. Surviving but not thriving: inconsistent responses of zooxanthellate jellyfish polyps to ocean warming and future UV-B scenarios

    OpenAIRE

    Klein, Shannon G.; Pitt, Kylie A.; Carroll, Anthony R.

    2016-01-01

    Complex changes to UV radiation at the Earth’s surface are occurring concurrently with ocean warming. Despite few empirical tests, jellyfish are hypothesised to be increasing in some parts of the world because they are robust to environmental stressors. Here we examine the effects of UV-B and ocean warming projections on zooxanthellate jellyfish polyps. We exposed Cassiopea sp. polyps to three levels of UV-B (future-low (1.43 Wm2), current (1.60 Wm2), future-high (1.77 Wm2)) and two levels of...

  19. OPTICAL CHARACTERISTICS OF NATURAL WATERS PROTECT AMPHIBIAN POPULATIONS FROM UV-B IN THE US PACIFIC NORTHWEST

    Science.gov (United States)

    Increased exposure to ultraviolet-B (UV-B) radiation has been proposed as a major environmental stressor leading to global amphibian declines. Prior experimental evidence from the US Pacific Northwest (PNW) indicating the acute embryonic sensitivity of at least 4 amphibian specie...

  20. Effect of moderate UV-B irradiation on Synechocystis PCC 6803 biliproteins

    International Nuclear Information System (INIS)

    In the present study, we investigated the mechanism of UV-B radiation induced damage to the light harvesting apparatus of the cyanobacterium Synechocystis 6803. Liquid chromatography analysis and spectroscopy investigations performed on phycobilisomes or isolated biliproteins irradiated with moderate UV-B intensity (1.3 W/m2) revealed rapid destruction of β-phycocyanin and a slower damage of the other biliproteins, α-phycocyanin and both α and β-allophycocyanin. EPR spin trapping measurements revealed that carbon centered adducts of the spin trap DMPO were formed. This evidence indicates that free radicals produced from bilins probably attack the polypeptide chain of protein inducing its degradation. Our results show that the bilin chromophore is the main target of UV-B irradiation, causing structural changes, which in turn induce reaction of the chromophore with atmospheric oxygen and lead to production of reactive radicals. Our results also demonstrate that β-phycocyanin is the most affected biliprotein, probably due to the presence of two bilins as chromophore

  1. Topical Administration of Manuka Oil Prevents UV-B Irradiation-Induced Cutaneous Photoaging in Mice

    Directory of Open Access Journals (Sweden)

    Oh Sook Kwon

    2013-01-01

    Full Text Available Manuka tree is indigenous to New Zealand, and its essential oil has been used as a traditional medicine to treat wounds, fever, and pain. Although there is a growing interest in the use of manuka oil for antiaging skin care products, little is known about its bioactivity. Solar ultraviolet (UV radiation is the primary environmental factor causing skin damage and consequently premature aging. Therefore, we evaluated manuka oil for its effects against photoaging in UV-B-irradiated hairless mice. Topical application of manuka oil suppressed the UV-B-induced increase in skin thickness and wrinkle grading in a dose-dependent manner. Application of 10% manuka oil reduced the average length, depth, and % area of wrinkles significantly, and this was correlated with inhibition of loss of collagen fiber content and epidermal hyperplasia. Furthermore, we observed that manuka oil could suppress UV-B-induced skin inflammation by inhibiting the production of inflammatory cytokines. Taken together, this study provides evidence that manuka oil indeed possesses antiphotoaging activity, and this is associated with its inhibitory activity against skin inflammation induced by UV irradiation.

  2. UV-B Induced Generation of Reactive Oxygen Species Promotes Formation of BFA-Induced Compartments in Cells of Arabidopsis Root Apices.

    Science.gov (United States)

    Yokawa, Ken; Kagenishi, Tomoko; Baluška, František

    2015-01-01

    UV-B radiation is an important part of the electromagnetic spectrum emitted by the sun. For much of the period of biological evolution organisms have been exposed to UV radiation, and have developed diverse mechanisms to cope with this potential stress factor. Roots are usually shielded from exposure to UV by the surrounding soil, but may nevertheless be exposed to high energy radiation on the soil surface. Due to their high sensitivity to UV-B radiation, plant roots need to respond rapidly in order to minimize exposure on the surface. In addition to root gravitropism, effective light perception by roots has recently been discovered to be essential for triggering negative root phototropism in Arabidopsis. However, it is not fully understood how UV-B affects root growth and phototropism. Here, we report that UV-B induces rapid generation of reactive oxygen species which in turn promotes the formation of BFA-induced compartments in the Arabidopsis root apex. During unilateral UV-B irradiation of roots changes in auxin concentration on the illuminated side have been recorded. In conclusion, UV-B-induced and ROS-mediated stimulation of vesicle recycling promotes root growth and induces negative phototropism.

  3. Appraisal of alternative skin model for the study of epidermal restoration following exposure to various environmental stress agents: ionising radiation and UV B; Evaluation d'un modele alternatif de peau dans l'etude de l'atteinte epidermique apres exposition a differents agents de stress environnementaux: rayonnements ionisants (RI) et ultra-violets B (UVB)

    Energy Technology Data Exchange (ETDEWEB)

    Isoir, M

    2006-06-15

    Human skin is a major target tissue for ionising radiation (IR) and UV B. We developed a skin explant model and used 2 types of keratinocytes to study survival and oxidative stress induced by these radiations. We examined oxidative damages by measuring R.O.S. produced and cellular anti-oxidant defenses induced. We observed into skin exposed to IR a modulation of genes expression implied in the control of oxidative stress, confirmed by the decrease of catalase, glutathione peroxidase and superoxide dismutase enzymatic activities. The imbalance observed between anti- and pro-apoptotic genes expression shows that keratinocytes apoptosis may be partly dependent on radio-induced R.O.S. production. We showed the difference of radiosensitivity between N.H.E.K. and Ha Ca.T., which may be linked to their differential oxidative responses. In addition, during re-epithelialising, we demonstrated that activated N.H.E.K. after IR express keratin 6, release pro-inflammatory cytokines and proliferate, without modification of their differentiation. Treatment of N.H.E.K. with geranyl geranylacetone (G.G.A.) has a beneficial effect on their radio-induced activation by increasing IL-1 release, their migration in scrapped area and their survival. G.G.A. has an anti apoptotic ability (induction of Hsp70- caspase-3 pathway) and migratory properties (P38/RhoA activation) on N.H.E.K., but after IR, only caspase-3 pathway is induced. This work thus contributes to the understanding of cutaneous damages after IR and G.G.A. mechanism of action which accelerates re-epithelialising. (author)

  4. UV-B induced generation of reactive oxygen species promotes formation of BFA-induced compartments in cells of Arabidopsis root apices

    Directory of Open Access Journals (Sweden)

    Ken eYokawa

    2016-01-01

    Full Text Available UV-B radiation is an important part of the electromagnetic spectrum emitted by the sun. For much of the period of biological evolution organisms have been exposed to UV radiation, and have developed diverse mechanisms to cope with this potential stress factor. Roots are usually shielded from exposure to UV by the surrounding soil, but may nevertheless be exposed to high energy radiationon the soil surface. Due to their high sensitivity to UV-B radiation, plant roots need to respond rapidly in order to minimize exposure on the surface. In addition to root gravitropism, effective light perception by roots has recently been discovered to be essential for triggering negative root phototropism in Arabidopsis. However, it is not fully understood how UV-B affects root growth and phototropism. Here, we report that UV-B induces rapid generation of reactive oxygen species which in turn promotes the formation of BFA-induced compartments in the Arabidopsis root apex. During unilateral UV-B irradiation of roots changes in auxin concentration on the illuminated side have been recorded. In conclusion, UV-B-induced and ROS-mediated stimulation of vesicle recycling promotes root growth and induces negative phototropism.

  5. Effect of Lanthanum (Ⅲ) on Reactive Oxygen Metabolism of Soybean Seedlings under Supplemental UV-B Irradiation

    Institute of Scientific and Technical Information of China (English)

    Yan Shengrong; Huang Xiaohua; Zhou Qing

    2007-01-01

    The effect of lanthanum (Ⅲ) on reactive oxygen metabolism of soybean seedlings under elevated ultraviolet-B radiation (UV-B: 280~320 nm) at 0.15 and 0.45 W·cm-2 levels respectively was studied through hydroponics in the laboratory. Plasmolemma permeability and contents of malonadialdehyde (MDA), hydrogen peroxide (H2O2), and proline gradually increased during the imposition of UV-B radiation and subsequently decreased during recovery from UV-B stress. The dynamic tendency of catalase (CAT) activity was similar to that of the above four indices. The activity of peroxidase (POD) initially increased, then remained at a high level, and finally dropped steeply when soybean seedlings were exposed to a low dosage of UV-B radiation. However, POD activity rose throughout and declined slightly on the eleventh day when soybean seedlings were stressed by a high dosage. With the addition of La(Ⅲ) of 20 mg·L-1, the rising tendency of plasmolemma permeability and contents of MDA, H2O2, and proline were slowed down during the stress period, whereas the declining speed was accelerated during the recovery period. The activities of CAT and POD were higher than those without La(Ⅲ) in all experiments. It suggested that the regulative effect of La(Ⅲ) on antioxidant enzymes such as CAT and POD could strengthen their capacities to scavenge reactive oxygen species (ROS), decrease contents of MDA and proline, and maintain normal plasmolemma permeability. Further more, the protective potential of La(Ⅲ) was better under low UV-B radiation than under a high one.

  6. High-power UV-B LEDs with long lifetime

    Science.gov (United States)

    Rass, Jens; Kolbe, Tim; Lobo-Ploch, Neysha; Wernicke, Tim; Mehnke, Frank; Kuhn, Christian; Enslin, Johannes; Guttmann, Martin; Reich, Christoph; Mogilatenko, Anna; Glaab, Johannes; Stoelmacker, Christoph; Lapeyrade, Mickael; Einfeldt, Sven; Weyers, Markus; Kneissl, Michael

    2015-03-01

    UV light emitters in the UV-B spectral range between 280 nm and 320 nm are of great interest for applications such as phototherapy, gas sensing, plant growth lighting, and UV curing. In this paper we present high power UV-B LEDs grown by MOVPE on sapphire substrates. By optimizing the heterostructure design, growth parameters and processing technologies, significant progress was achieved with respect to internal efficiency, injection efficiency and light extraction. LED chips emitting at 310 nm with maximum output powers of up to 18 mW have been realized. Lifetime measurements show approximately 20% decrease in emission power after 1,000 operating hours at 100 mA and 5 mW output power and less than 30% after 3,500 hours of operation, thus indicating an L50 lifetime beyond 10,000 hours.

  7. The Methoxyflavonoid Isosakuranetin Suppresses UV-B-Induced Matrix Metalloproteinase-1 Expression and Collagen Degradation Relevant for Skin Photoaging

    Science.gov (United States)

    Jung, Hana; Lee, Eunjoo H.; Lee, Tae Hoon; Cho, Man-Ho

    2016-01-01

    Solar ultraviolet (UV) radiation is a main extrinsic factor for skin aging. Chronic exposure of the skin to UV radiation causes the induction of matrix metalloproteinases (MMPs), such as MMP-1, and consequently results in alterations of the extracellular matrix (ECM) and skin photoaging. Flavonoids are considered as potent anti-photoaging agents due to their UV-absorbing and antioxidant properties and inhibitory activity against UV-mediated MMP induction. To identify anti-photoaging agents, in the present study we examined the preventative effect of methoxyflavonoids, such as sakuranetin, isosakuranetin, homoeriodictyol, genkwanin, chrysoeriol and syringetin, on UV-B-induced skin photo-damage. Of the examined methoxyflavonoids, pretreatment with isosakuranetin strongly suppressed the UV-B-mediated induction of MMP-1 in human keratinocytes in a concentration-dependent manner. Isosakuranetin inhibited UV-B-induced phosphorylation of mitogen-activated protein kinase (MAPK) signaling components, ERK1/2, JNK1/2 and p38 proteins. This result suggests that the ERK1/2 kinase pathways likely contribute to the inhibitory effects of isosakuranetin on UV-induced MMP-1 production in human keratinocytes. Isosakuranetin also prevented UV-B-induced degradation of type-1 collagen in human dermal fibroblast cells. Taken together, our findings suggest that isosakuranetin has the potential for development as a protective agent for skin photoaging through the inhibition of UV-induced MMP-1 production and collagen degradation. PMID:27598131

  8. The Methoxyflavonoid Isosakuranetin Suppresses UV-B-Induced Matrix Metalloproteinase-1 Expression and Collagen Degradation Relevant for Skin Photoaging.

    Science.gov (United States)

    Jung, Hana; Lee, Eunjoo H; Lee, Tae Hoon; Cho, Man-Ho

    2016-01-01

    Solar ultraviolet (UV) radiation is a main extrinsic factor for skin aging. Chronic exposure of the skin to UV radiation causes the induction of matrix metalloproteinases (MMPs), such as MMP-1, and consequently results in alterations of the extracellular matrix (ECM) and skin photoaging. Flavonoids are considered as potent anti-photoaging agents due to their UV-absorbing and antioxidant properties and inhibitory activity against UV-mediated MMP induction. To identify anti-photoaging agents, in the present study we examined the preventative effect of methoxyflavonoids, such as sakuranetin, isosakuranetin, homoeriodictyol, genkwanin, chrysoeriol and syringetin, on UV-B-induced skin photo-damage. Of the examined methoxyflavonoids, pretreatment with isosakuranetin strongly suppressed the UV-B-mediated induction of MMP-1 in human keratinocytes in a concentration-dependent manner. Isosakuranetin inhibited UV-B-induced phosphorylation of mitogen-activated protein kinase (MAPK) signaling components, ERK1/2, JNK1/2 and p38 proteins. This result suggests that the ERK1/2 kinase pathways likely contribute to the inhibitory effects of isosakuranetin on UV-induced MMP-1 production in human keratinocytes. Isosakuranetin also prevented UV-B-induced degradation of type-1 collagen in human dermal fibroblast cells. Taken together, our findings suggest that isosakuranetin has the potential for development as a protective agent for skin photoaging through the inhibition of UV-induced MMP-1 production and collagen degradation. PMID:27598131

  9. The Methoxyflavonoid Isosakuranetin Suppresses UV-B-Induced Matrix Metalloproteinase-1 Expression and Collagen Degradation Relevant for Skin Photoaging

    Directory of Open Access Journals (Sweden)

    Hana Jung

    2016-09-01

    Full Text Available Solar ultraviolet (UV radiation is a main extrinsic factor for skin aging. Chronic exposure of the skin to UV radiation causes the induction of matrix metalloproteinases (MMPs, such as MMP-1, and consequently results in alterations of the extracellular matrix (ECM and skin photoaging. Flavonoids are considered as potent anti-photoaging agents due to their UV-absorbing and antioxidant properties and inhibitory activity against UV-mediated MMP induction. To identify anti-photoaging agents, in the present study we examined the preventative effect of methoxyflavonoids, such as sakuranetin, isosakuranetin, homoeriodictyol, genkwanin, chrysoeriol and syringetin, on UV-B-induced skin photo-damage. Of the examined methoxyflavonoids, pretreatment with isosakuranetin strongly suppressed the UV-B-mediated induction of MMP-1 in human keratinocytes in a concentration-dependent manner. Isosakuranetin inhibited UV-B-induced phosphorylation of mitogen-activated protein kinase (MAPK signaling components, ERK1/2, JNK1/2 and p38 proteins. This result suggests that the ERK1/2 kinase pathways likely contribute to the inhibitory effects of isosakuranetin on UV-induced MMP-1 production in human keratinocytes. Isosakuranetin also prevented UV-B-induced degradation of type-1 collagen in human dermal fibroblast cells. Taken together, our findings suggest that isosakuranetin has the potential for development as a protective agent for skin photoaging through the inhibition of UV-induced MMP-1 production and collagen degradation.

  10. Ultraviolet-B radiation alters phenolic salicylate and flavenoid composition of Populus trichocarpa leaves

    Energy Technology Data Exchange (ETDEWEB)

    Warren, J. M. [USDA Forest Service, Forestry Science Laboratory, Corwallis, OR (United States); Bassman, J. H. [Washington State Univ., Dept. of Natural Resources Sciences, Pullman, WA (United States); Fellman, J. K.; Mattinson, D. S. [Washington State Univ., Dept. of Horticulture and Landscape Architecture, Pullman, WA (United States); Eigenbrode, S. [Idaho Univ., Dept. of Plant, Soil and Entomological Sciences, Moscow, ID (United States)

    2003-06-01

    Foliar phenolic composition of field- and greenhouse-grown black cottonwood was studied by subjecting samples to near zero, ambient and twice-ambient concentrations of biologically effective ultraviolet-B radiation. Phenolic compounds were extracted after three months, separated by liquid chromatography and identified and quantified by diode-array spectrometry and mass spectrometry. Phenolic compounds that were found to have increased in response to UV-B radiation were flavonoids, although increasing the level of radiation to ambient and twice ambient levels did not result in further flavonoid accumulation in either greenhouse or field samples. There was, however, an increase in salicortin, a non-flavonoid glycoside, and a salicylates that is important in plant-herbivore-predator relationships. It was concluded that enhanced solar UV-B radiation has the capacity to significantly alter trophic structure in some ecosystems by stimulating specific phenolic compounds. 74 refs., 1 tab., 6 figs.

  11. Interactive effects of supplemental UV-B and temperature in European aspen seedlings: Implications for growth, leaf traits, phenolic defense and associated organisms.

    Science.gov (United States)

    Randriamanana, Tendry R; Lavola, Anu; Julkunen-Tiitto, Riitta

    2015-08-01

    Past studies reveal opposite effects of elevated UV-B and temperature on plant growth and concentrations of UV-B absorbing compounds, yet few studies have dealt with the combined and interactive effects of these two climate change factors on woody dioecious plants. We investigated the interactive effects of UV-B and temperature treatments on growth, leaf traits and phenolic concentrations in Populus tremula L. (European aspen) seedlings. We also considered the consequences of these effects on their associated organisms: herbivorous insects, rust pathogens, the presence of endophytic fungi and whether or not the responses differ between genders and genotypes. Supplemental temperature and UV-B were modulated to +2 °C and +30.77% above ambient conditions, respectively. Warming increased growth, photosynthesis and foliar nitrogen concentration but reduced leaf thickness and phenolic concentrations. On the other hand, supplemental UV-B increased total phenolic glycosides, mainly flavonols and phenolic acids, and partially counteracted the positive effects of warming on growth. Fast growing genotypes were less susceptible to the growth-reducing effect of combined UVB + T, less infected with rust disease and less prone to insect damage probably due to their higher salicylate and lower nitrogen concentrations. Under ambient temperature, the males of European aspen were taller and had bigger leaves than the females, while under elevated temperature, females grew bigger and, under UV-B, had more tremulacin than males. The multiple interactive effects of UV-B and temperature on growth, leaf traits and phenolic compounds, highlight the importance of multifactor experiments as a realistic predictor of plant responses to climate change.

  12. COP1 is required for UV-B-induced nuclear accumulation of the UVR8 photoreceptor.

    Science.gov (United States)

    Yin, Ruohe; Skvortsova, Mariya Y; Loubéry, Sylvain; Ulm, Roman

    2016-07-26

    The UV-B photoreceptor UV RESISTANCE LOCUS 8 (UVR8) promotes UV-B acclimation and tolerance in Arabidopsis thaliana UVR8 localizes to both cytosol and nucleus, but its main activity is assumed to be nuclear. UV-B photoreception stimulates nuclear accumulation of UVR8 in a presently unknown manner. Here, we show that CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) is required for UV-B-induced nuclear accumulation of UVR8, but bypassing the COP1 requirement for UVR8 nuclear accumulation did not rescue the cop1 mutant UV-B phenotype. Using a glucocorticoid receptor (GR)-based fusion protein system to conditionally localize GR-UVR8 to the nucleus, we have demonstrated that both photoactivation and nuclear localization of UVR8 are required for UV-B-induced photomorphogenic responses. In contrast, there was no UV-B response when UV-B-activated UVR8 was artificially retained in the cytosol. In agreement with a predominantly nuclear activity, constitutively active UVR8(W285A) accumulated in the nucleus also in the absence of UV-B. Furthermore, GR-COP1 expression lines suggested that UV-B-activated UVR8 can be coimported into the nucleus by COP1. Our data strongly support localization of UVR8 signaling in the nucleus and a dual role for COP1 in the regulation of UV-B-induced UVR8 nuclear accumulation and in UVR8-mediated UV-B signaling. PMID:27407149

  13. Ozone, cloud, solar and UV-B levels at a low pollution, southern hemisphere, sub-tropical site for winter/spring 1995

    International Nuclear Information System (INIS)

    This paper analyses daily ozone, cloud cover, solar radiation and ultraviolet waveband (UV-B) data for winter/spring at a low pollution Southern Hemispheric sub-tropical site (27.80 deg south). Relationships of meteorological factors and UV-B levels and the implications for humans will be discussed. The average ozone concentration for the period was 290 Dobson Units (DU). An anti-correlation is presented between the ozone and UV-B data over a 5 day period during winter. An ozone deficiency of 45 DU was calculated for the cloud free day on the 16th July, 1995, in which the UV-B level exceeded the clear sky envelope by about 6%. Part of this increase may be attributed to a decrease in cloud cover. In winter, the July average of the daily integrated UV-B irradiance was 29.0 kJ/m2, (a level which is comparable to that observed in Japan during the summer months). The high measured UV-B irradiance, shows that it is necessary even in winter to minimise UV exposure at sub-tropical location

  14. ambiental

    Directory of Open Access Journals (Sweden)

    Roque Leal Salcedo

    2008-01-01

    Full Text Available El derecho internacional ambiental es un conocimiento de carácter transversal, que entre otras consideraciones refleja las preocupaciones de la sociedad por la implementación de un modelo de desarrollo sustentable para el respeto a las reglas del medio natural que garantizan la integridad y renovación de los sistemas naturales. El presente artículo enfoca esta visión a través del análisis de material documental revisado, entre ellos tratados internacionales que permiten distinguir el desarrollo del derecho internacional ambiental y el papel de Organización de las Naciones Unidas (ONU, en el propósito común del derecho individual y colectivo de disfrutar de una vida, un ambiente seguro, sano y ecológicamente equilibrado. En función a estas disertaciones las consideraciones finales exponen parte de la visión que ha estructurado la ONU y que representan un aporte considerable en el fomento de la conciencia mundial sobre la necesidad de establecer vínculos entre las naciones para el continuo desarrollo de esta rama del derecho.

  15. Effect of He-Ne Laser Radiation on Component,Content of the Flavonoids and Growth Parameters in Beta vulgaris under Enhanced UV-B Radiation%He-Ne激光和紫外-B辐射对红梗牛皮菜黄酮类化合物成分、含量及生长的影响

    Institute of Scientific and Technical Information of China (English)

    张晋豫; 邱宗波; 王勋陵; 岳明

    2008-01-01

    分别用He-Ne激光(5.23 mW/mm2,5 min/d)和紫外-B辐射(UV-B,280~320 nm)(强度12 μW/cm2,8 h/d)及二者复合处理红梗牛皮菜(Beta vulgaris var.cicila),然后通过水解比色和高效液相色谱(HPLC)法分析叶中甲醇水溶性黄酮类化合物,并测定形态与生长指标.结果表明,UV-B辐射处理后黄酮类化合物含量增加到对照的160%,但激光复合处理后,则恢复到略高于对照的水平.其中槲皮素和黄酮在各处理组中变化非常显著,槲皮素在UV-B(B)、He-Ne激光(L)及二者复合(BL)处理后被大量诱导;而黄酮仅在对照组(CK)和L组出现.分析表明,He-Ne激光与UV-B辐射一样,对黄酮类化合物的诱导是具有选择性的,具有高UV吸收并具较高抗氧化作用的化合物更容易被诱导.因此He-Ne激光很可能通过这种选择机制来减轻UV-B导致的伤害.

  16. Cloud forming properties of ambient aerosol in the Netherlands and resultant shortwave radiative forcing of climate.

    NARCIS (Netherlands)

    Khlystov, A.

    1998-01-01

    This thesis discusses properties of ambient aerosols in the Netherlands which are controlling the magnitude of the local aerosol radiative forcing. Anthropogenic aerosols influence climate by changing the radiative transfer through the atmosphere via two effects, one is direct and a second is indire

  17. Effects of enhanced UV-B on pigment-based phytoplankton biomass and composition of mesocosm-enclosed natural marine communities from three latitudes.

    Science.gov (United States)

    Roy, Suzanne; Mohovic, Bruna; Gianesella, Sônia M F; Schloss, Irene; Ferrario, Martha; Demers, Serge

    2006-01-01

    (which were the lowest of the three sites), high irradiances (which were the highest noon incident photosynthetically available radiation and UV of the three sites) and UV-B penetration down to the bottom of the mesocosms. In Ushuaia a small bloom took place over the first 5 days. The RM-ANOVA showed no overall effect of the UV-B treatments for any of the pigments examined but on the last 3 days of the experiment several green algae-type pigments, such as Chl b and siphonein, showed increased concentrations under the HUVB treatment. UV-B enhancement hence favored green algae, as seen from the stronger increase over time in the ratio of Chl b to Chl a associated with the HUVB treatment. UV-B enhancement also seemed to cause a slight decrease in physiological condition, because the relative concentration of chlorophyllide a and some pheophorbides that may be the product of dying algae increased during the HUVB treatments in Ubatuba and particularly in Ushuaia (where UV-B also penetrated to the bottom of mesocosms). For all three sites changes in phytoplankton biomass due to the UV-B treatments were minor, even though UV-B enhancement was important. This study indicates that effects of enhanced UV-B on the community structure of both phytoplankton and their grazers are potentially more important than effects on overall algal biomass. PMID:17205624

  18. Environmental policy. Ambient radioactivity levels and radiation doses in 1996

    International Nuclear Information System (INIS)

    The report is intended as information for the German Bundestag and Bundesrat as well as for the general population interested in issues of radiological protection. The information presented in the report shows that in 1996, the radiation dose to the population was low and amounted to an average of 4 millisievert (mSv), with 60% contributed by natural radiation sources, and 40% by artificial sources. The major natural source was the radioactive gas radon in buildings. Anthropogenic radiation exposure almost exclusively resulted from application of radioactive substances and ionizing radiation in the medical field, for diagnostic purposes. There still is a potential for reducing radiation doses due to these applications. In the reporting year, there were 340 000 persons occupationally exposed to ionizing radiation. Only 15% of these received a dose different from zero, the average dose was 1.8 mSv. The data show that the anthropogenic radiation exposure emanating from the uses of atomic energy or applications of ionizing radiation in technology is very low. (orig./CB)

  19. Environmental policy. Ambient radioactivity levels and radiation doses in 1998

    International Nuclear Information System (INIS)

    The report contains information on the natural (background) radiation exposure (chapter II), the natural radiation exposure as influenced by anthropogenic effects (chapter III), the anthropogenic radiation exposure (chapter IV), and the radiation doses to the environment and the population emanating from the Chernobyl fallout (chapter V). The natural radiation exposure is specified referring to the contributions from cosmic and terrestrial background radiation and intake of natural radioactive substances. Changes of the natural environment resulting from anthropogenic effects (technology applications) inducing an increase in concentration of natural radioactive substances accordingly increase the anthropogenic radiation exposure. Indoor air radon concentration in buildings for instance is one typical example of anthropogenic increase of concentration of natural radioactivity, primarily caused by the mining industry or by various materials processing activities, which may cause an increase in the average radiation dose to the population. Measurements so far show that indoor air concentration of radon exceeds a level of 200 Bq/m3 in less than 2% of the residential buildings; the EUropean Commission therefore recommends to use this concentration value as a maximum value for new residential buildings. Higher concentrations are primarily measured in areas with relevant geological conditions and abundance of radon, or eg. in mining areas. (orig./CB)

  20. The influence of enhanced UV-B irradiation on the growth and composition of plants

    International Nuclear Information System (INIS)

    Barley (Hordeum vulgare), corn (Zea mays), bean (Phaseolus vulgaris), and radish (Raphanus Sativus) were irradiated under a lighting device for 5 to 10 days continuously at an increased UV-B fluence rate. These four species reacted differently to the elevated UV-radiation in their growth parameters, composition and leaf surface. Bean seedlings incurred the greatest damage, radish and barley seedlings less damage, and corn seedlings were hardly affected. The fresh weight, loaf area and chlorophyll, carstenoid and galactolipid contents were reduced in all species, whereas protein contents were increased throughout compared to controls. An approx. 50% increase in flavaroid content was noted in barley and radish seedlings. Studies on barley seedlings showed the effects on growth parameters and composition to be more market with increasing UV-B fluence rate. Fresh weights, chlorophyll and carotinoid contents were reduced proportionately, in contrast to flavaroid content which increased with increasing fluence rate to 180% of the control value. A bronze discolouration of the leaves appeared regularly at the highest fluence rate. (orig./AJ)

  1. Cloud forming properties of ambient aerosol in the Netherlands and resultant shortwave radiative forcing of climate.

    OpenAIRE

    Khlystov, A.

    1998-01-01

    This thesis discusses properties of ambient aerosols in the Netherlands which are controlling the magnitude of the local aerosol radiative forcing. Anthropogenic aerosols influence climate by changing the radiative transfer through the atmosphere via two effects, one is direct and a second is indirect. Due to the scattering of solar light on aerosol particles the Earth surface receives less radiation and thus cools, which is called the direct aerosol effect.The indirect effect includes proces...

  2. The Effects of Ambient Conditions on Helicopter Harmonic Noise Radiation: Theory and Experiment

    Science.gov (United States)

    Greenwood, Eric; Sim, Ben W.; Boyd, D. Douglas, Jr.

    2016-01-01

    The effects of ambient atmospheric conditions, air temperature and density, on rotor harmonic noise radiation are characterized using theoretical models and experimental measurements of helicopter noise collected at three different test sites at elevations ranging from sea level to 7000 ft above sea level. Significant changes in the thickness, loading, and blade-vortex interaction noise levels and radiation directions are observed across the different test sites for an AS350 helicopter flying at the same indicated airspeed and gross weight. However, the radiated noise is shown to scale with ambient pressure when the flight condition of the helicopter is defined in nondimensional terms. Although the effective tip Mach number is identified as the primary governing parameter for thickness noise, the nondimensional weight coefficient also impacts lower harmonic loading noise levels, which contribute strongly to low frequency harmonic noise radiation both in and out of the plane of the horizon. Strategies for maintaining the same nondimensional rotor operating condition under different ambient conditions are developed using an analytical model of single main rotor helicopter trim and confirmed using a CAMRAD II model of the AS350 helicopter. The ability of the Fundamental Rotorcraft Acoustics Modeling from Experiments (FRAME) technique to generalize noise measurements made under one set of ambient conditions to make accurate noise predictions under other ambient conditions is also validated.

  3. Efeitos da radiação ultravioleta-B sobre a morfologia foliar de Arabidopsis thaliana (L. Heynh. (Brassicaceae Effects of ultraviolet-B radiation on leaf morphology of Arabidopsis thaliana (L. Heynh. (Brassicaceae

    Directory of Open Access Journals (Sweden)

    Maria Regina Torres Boeger

    2006-06-01

    Full Text Available A redução da camada de ozônio resulta no aumento da radiação ultravioleta que atinge a superfície terrestre, especialmente a radiação ultravioletaB (UV-B. O aumento da radiação poderá induzir a mudanças estruturais e fisiológicas nas plantas, influenciando no seu crescimento e desenvolvimento. O objetivo deste trabalho foi determinar os efeitos da radiação UV-B ambiente sobre a morfologia das folhas de Arabidopsis thaliana desenvolvidas em condições controladas. As sementes de A. thaliana cresceram em câmaras de crescimento, com 300 µmol m-2s-1 de radiação fotossinteticamente ativa (PAR com ou sem 6 kJ m-2 s-1 de radiação UV-Bbe (UV-Bbe; UV-B biologicamente efetiva. Após 21 dias, 10 folhas de cada tratamento (com e sem radiação UV-B foram coletadas para avaliar área foliar, massa fresca e seca, AEF, densidades estomáticas e de tricomas de ambas as faces da folha, espessura da lâmina foliar e concentração de compostos fenólicos e de clorofila total, a e b. As folhas tratadas com radiação UV-B apresentaram menor área foliar, massa fresca e seca, densidade de tricomas na face adaxial e densidade de estômatos na face abaxial da folha. Entretanto, apresentaram os maiores valores médios de espessura total da lâmina e do mesofilo, maior concentração de clorofila total, clorofila a e clorofila b e compostos fenólicos foliares do que as folhas não tratadas com radiação UV-B. Essas diferenças morfológicas significativas (p Reduction of the ozone layer results in the increase in ultraviolet radiation reaching the earth's surface, especially the ultraviolet-B (UV-B. The increase of radiation may induce structural and physiological changes in plants, influencing their growth and development. This paper evaluates the effects of ambient UV-B radiation upon to the leaf morphology of Arabidopsis thaliana developed under controlled conditions. The seeds of A. thaliana grown in environmental chamber, with 300 µmol m-2

  4. Ambient ultraviolet radiation induces protective responses in soybean but does not attenuate indirect defense

    Energy Technology Data Exchange (ETDEWEB)

    Winter, Thorsten R. [Department of Botany II, Julius-von-Sachs Institute for Biosciences, University of Wuerzburg, Julius-von-Sachs-Platz 3, 97082 Wuerzburg (Germany); Rostas, Michael [Department of Botany II, Julius-von-Sachs Institute for Biosciences, University of Wuerzburg, Julius-von-Sachs-Platz 3, 97082 Wuerzburg (Germany)], E-mail: rostas@botanik.uni-wuerzburg.de

    2008-09-15

    We investigated the effects of ambient ultraviolet (UV) radiation on (i) the performance and chemistry of soybean plants, (ii) the performance of Spodoptera frugiperda and (iii) the foraging behavior of the herbivore's natural enemy Cotesia marginiventris which exploits herbivore-induced plant volatiles (VOC) for host location. The accumulation of protective phenolics was faster in plants receiving ambient UV than in controls exposed to sun light lacking UV. Accordingly, isorhamnetin- and quercetin-based flavonoids were increased in UV exposed plants. No UV effects were found on the performance and feeding behavior of S. frugiperda. Herbivore-damaged plants emitted the same VOC when grown under ambient or attenuated UV for 5, 10 or 30 days. Consequently, C. marginiventris was attracted but did not discriminate between exposed and unexposed soybeans. In summary, ambient UV radiation affected soybean morphology and physiology but did not destabilize interactions between trophic levels. - Ambient ultraviolet radiation does not alter induced VOC emission in soybean and thus host location of the parasitoid Cotesia marginiventris remains effective.

  5. Levels of prostaglandins and arachidonic acid in UV-B irradiated human skin before and after topical application of benzyl-2,5-diacetoxybenzoate, a salicylic acid derivative

    Energy Technology Data Exchange (ETDEWEB)

    Barr, R.M.; Black, A.K.; Mallet, A.I.; Greaves, M.W.

    1982-07-01

    Benzyl-2,5-diacetoxybenzoate (BDAB) was tested for anti-inflammatory activity on experimentally inflamed skin. Human abdominal skin was irradiated with three minimal erythema doses of UV-B (290-320nm) radiation to give a maximum erythema at 24 hours with an associated rise in PGE2 and PGF2 alpha levels measured by gas chromatography-mass spectrometry. Topical application of a 1% w/w preparation of BDAB neither decreased the evoked erythema nor diminished the rise in PGE2 and PGF2 alpha concentrations. BDAB, applied topically, was judged to be ineffectual as an anti-inflammatory agent in UV-B erythema.

  6. Depletion of stratospheric ozone over the Antarctic and Arctic : Responses of plants of polar terrestrial ecosystems to enhanced UV-B, an overview

    NARCIS (Netherlands)

    Rozema, Jelte; Boelen, Peter; Blokker, Peter

    2005-01-01

    Depletion of stratospheric ozone over the Antarctic has been re-occurring yearly since 1974, leading to enhanced UV-B radiation. Arctic ozone depletion has been observed since 1990. Ozone recovery has been predicted by 2050, but no signs of recovery occur. Here we review responses of polar plants to

  7. Direct and indirect effects of UV-B exposure on litter decomposition: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Xinzhang Song

    Full Text Available Ultraviolet-B (UV-B exposure in the course of litter decomposition may have a direct effect on decomposition rates via changing states of photodegradation or decomposer constitution in litter while UV-B exposure during growth periods may alter chemical compositions and physical properties of plants. Consequently, these changes will indirectly affect subsequent litter decomposition processes in soil. Although studies are available on both the positive and negative effects (including no observable effects of UV-B exposure on litter decomposition, a comprehensive analysis leading to an adequate understanding remains unresolved. Using data from 93 studies across six biomes, this introductory meta-analysis found that elevated UV-B directly increased litter decomposition rates by 7% and indirectly by 12% while attenuated UV-B directly decreased litter decomposition rates by 23% and indirectly increased litter decomposition rates by 7%. However, neither positive nor negative effects were statistically significant. Woody plant litter decomposition seemed more sensitive to UV-B than herbaceous plant litter except under conditions of indirect effects of elevated UV-B. Furthermore, levels of UV-B intensity significantly affected litter decomposition response to UV-B (P<0.05. UV-B effects on litter decomposition were to a large degree compounded by climatic factors (e.g., MAP and MAT (P<0.05 and litter chemistry (e.g., lignin content (P<0.01. Results suggest these factors likely have a bearing on masking the important role of UV-B on litter decomposition. No significant differences in UV-B effects on litter decomposition were found between study types (field experiment vs. laboratory incubation, litter forms (leaf vs. needle, and decay duration. Indirect effects of elevated UV-B on litter decomposition significantly increased with decay duration (P<0.001. Additionally, relatively small changes in UV-B exposure intensity (30% had significant direct effects

  8. Direct and indirect effects of UV-B exposure on litter decomposition: a meta-analysis.

    Science.gov (United States)

    Song, Xinzhang; Peng, Changhui; Jiang, Hong; Zhu, Qiuan; Wang, Weifeng

    2013-01-01

    Ultraviolet-B (UV-B) exposure in the course of litter decomposition may have a direct effect on decomposition rates via changing states of photodegradation or decomposer constitution in litter while UV-B exposure during growth periods may alter chemical compositions and physical properties of plants. Consequently, these changes will indirectly affect subsequent litter decomposition processes in soil. Although studies are available on both the positive and negative effects (including no observable effects) of UV-B exposure on litter decomposition, a comprehensive analysis leading to an adequate understanding remains unresolved. Using data from 93 studies across six biomes, this introductory meta-analysis found that elevated UV-B directly increased litter decomposition rates by 7% and indirectly by 12% while attenuated UV-B directly decreased litter decomposition rates by 23% and indirectly increased litter decomposition rates by 7%. However, neither positive nor negative effects were statistically significant. Woody plant litter decomposition seemed more sensitive to UV-B than herbaceous plant litter except under conditions of indirect effects of elevated UV-B. Furthermore, levels of UV-B intensity significantly affected litter decomposition response to UV-B (PUV-B effects on litter decomposition were to a large degree compounded by climatic factors (e.g., MAP and MAT) (PUV-B on litter decomposition. No significant differences in UV-B effects on litter decomposition were found between study types (field experiment vs. laboratory incubation), litter forms (leaf vs. needle), and decay duration. Indirect effects of elevated UV-B on litter decomposition significantly increased with decay duration (PUV-B exposure intensity (30%) had significant direct effects on litter decomposition (PUV-B on litter decomposition.

  9. Multiplex polymerase chain reaction analysis of UV-A- and UV-B-induced delayed and early mutations in V79 Chinese hamster cells.

    Science.gov (United States)

    Dahle, Jostein; Noordhuis, Paul; Stokke, Trond; Svendsrud, Debbie Hege; Kvam, Egil

    2005-01-01

    We previously reported that approximately 10% of V79 Chinese hamster fibroblast populations clonally derived from single cells immediately after irradiation with either ultraviolet B (UV-B, 290-320 nm, mainly 311 nm) or ultraviolet A (UV-A, 320-400 nm, mainly 350-390 nm) radiation exhibit genomic instability. The instability is revealed by relatively high mutation frequencies in the hypoxanthine phosphoribosyl transferase (hprt) gene up to 23 cell generations after irradiation. These delayed mutant clones exhibited higher levels of oxidative stress than normal cells. Therefore, persistently increased oxidative stress has been proposed as a mechanism for UV-induced genomic instability. This study investigates whether this mechanism is reflected in the deletion spectrum of delayed mutant clones. Eighty-eight percent of the delayed mutant clones derived from UV-A-irradiated populations were found to have total deletion of the hprt gene. Correspondingly, 81% of UV-A-induced early mutations (i.e. detected shortly after irradiation) also had total deletions. Among delayed UV-B-induced mutant clones, 23% had total deletions and 8% had deletion of one exon, whereas all early UV-B events were either point mutations or small deletions or insertions. In conclusion, the multiplex polymerase chain reaction deletion screen showed that there were explicit differences in the occurrence of large gene alterations between early and delayed mutations induced by UV-B radiation. For UV-A radiation the deletion spectra were similar for delayed and early mutations. UV-A radiation is, in contrast to UV-B radiation, only weakly absorbed by DNA and probably induces mutation almost solely via production of reactive oxygen species. Therefore, the present results support the hypothesis that persistent increase in oxidative stress is involved in the mechanism of UV-induced genomic instability.

  10. Field research on the effects of UV-B filters on terrestrial Antarctic vegetation

    NARCIS (Netherlands)

    Huiskes, A.H.L.; Lud, D.; Moerdijk-Poortvliet, T.C.W.

    2001-01-01

    Patches of vegetation of six common species growing on Leonie Island (67 degrees 35' S, 68 degrees 20' W), Antarctic Peninsula region were covered with either UV-B transparent perspex screens or UV-B absorbing screens. Uncovered plots served as a control. Temperature and relative humidity were monit

  11. Ambient radiation levels in positron emission tomography/computed tomography (PET/CT) imaging center

    Energy Technology Data Exchange (ETDEWEB)

    Santana, Priscila do Carmo; Oliveira, Paulo Marcio Campos de; Mamede, Marcelo; Silveira, Mariana de Castro; Aguiar, Polyanna; Real, Raphaela Vila, E-mail: pridili@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Silva, Teogenes Augusto da [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-01-15

    Objective: to evaluate the level of ambient radiation in a PET/CT center. Materials and methods: previously selected and calibrated TLD-100H thermoluminescent dosimeters were utilized to measure room radiation levels. During 32 days, the detectors were placed in several strategically selected points inside the PET/CT center and in adjacent buildings. After the exposure period the dosimeters were collected and processed to determine the radiation level. Results: in none of the points selected for measurements the values exceeded the radiation dose threshold for controlled area (5 mSv/ year) or free area (0.5 mSv/year) as recommended by the Brazilian regulations. Conclusion: in the present study the authors demonstrated that the whole shielding system is appropriate and, consequently, the workers are exposed to doses below the threshold established by Brazilian standards, provided the radiation protection standards are followed. (author)

  12. Effect of ambient pressure and radiation reabsorption of atmosphere on the flame spreading over thermally thin combustibles in microgravity

    Institute of Scientific and Technical Information of China (English)

    杜文峰; 胡文瑞

    2003-01-01

    For the flame spread over thermally thin combustibles in an atmosphere, if the atmosphere cannot emit and absorb the thermal radiation (e.g. for atmosphere of O2-N2), the conductive heat transfer from the flame to the fuel surface dominates the flame spread at lower ambient atmosphere. As the ambient pressure increases, the flame spread rate increases, and the radiant heat transfer from the flame to the fuel surface gradually becomes the dominant driving force for the flame spread. In contrast, if the atmosphere is able to emit and absorb the thermal radiation (e.g. for atmosphere of O2-CO2), at lower pressure, the heat transfer from flame to the fuel surface is enhanced by the radiation reabsorption of the atmosphere at the leading edge of the flame, and both conduction and thermal radiation play important roles in the mechanism of flame spread. With the increase in ambient pressure, the oxygen diffuses more quickly from ambient atmosphere into the flame, the chemical reaction in the flame is enhanced, and the flame spread rate increases. When the ambient pressure is greater than a critical value, the thermal radiation from the flame to the solid surface is hampered by the radiation reabsorption of ambient atmosphere with the further increase in ambient pressure. As a result, with the increase in ambient pressure, the flame spread rate decreases and the heat conduction gradually dominates the flame spread over the fuel surface.

  13. Isolation of UV-B resistant bacteria from two high altitude Andean lakes (4,400 m) with saline and non saline conditions.

    Science.gov (United States)

    Flores, María R; Ordoñez, Omar F; Maldonado, Marcos J; Farías, María E

    2009-12-01

    Laguna (L.) Negra and L. Verde are high altitude Andean lakes located at the 4,400 m altitude in the Andean desert (Puna) in the Argentine northwest. Both lakes are exposed to extreme weather conditions but differ in salinity contents (salinity 6.7% for L. Negra and 0.27% for L. Verde). The aim of this work was to isolate ultraviolet B fraction (UV-B) resistant bacteria under UV-stress in order to determine, a possible connection, between resistance to UV-B and tolerance to salinity. DNA damage was determined by measuring CPDs accumulation. Connection among pigmentation production and UV resistance was also studied. Water samples were exposed to artificial UV-B radiation for 24 h. Water aliquots were plated along the exposition on different media, with different salinity and carbon source content (Lake medium (LM) done with the lake water plus agar and LB). CFU were counted and DNA damage accumulation was determined. Isolated bacteria were identified by 16S rDNA sequence. Their salinity tolerance, were measured at 1, 5 and 10% NaCl and their pigment production in both media was determined. In general it was found that UV resistance and pigment production were the optimum in Lake Medium done with lake water which maintained similar salinity. The most resistant bacteria in L. Negra were different strains of Exiguobacterium sp. and, in L. Verde, Staphylococcus sp. and Stenotrophomonas maltophilia. These bacteria showed the production and increase of UV-Vis absorbing compounds under UV stress and in LM. Bacterial communities from both lakes were well adapted to high UV-B exposure under the experimental conditions, and in many cases UV-B even stimulated growth. The idea that resistance to UV-B could be related to adaptation to high salinity is still an open question that has to be answered with future experiments. PMID:20118609

  14. Synthesis of Nanoscale Tips Using Femtosecond Laser Radiation under Ambient Condition

    OpenAIRE

    Venkatakrishnan K; Sivakumar M; Tan B

    2009-01-01

    Abstract We report a unique growth of platelet-shaped nanoscale tips of transparent dielectric using femtosecond laser radiation at MHz pulse repetition rate with nitrogen background gas flow under ambient condition. The tips grew with sharp nanoscale apex while their base and lengths are of the order of few hundred nanometers. In the absence of nitrogen, the irradiation leads to nanofibrous structure formation. The collision between the nitrogen gas atoms and the vapor species slows down plu...

  15. UV-B modulates the interplay between terpenoids and flavonoids in peppermint (Mentha x piperita L.).

    Science.gov (United States)

    Dolzhenko, Yuliya; Bertea, Cinzia M; Occhipinti, Andrea; Bossi, Simone; Maffei, Massimo E

    2010-08-01

    Modulation of secondary metabolites by UV-B involves changes in gene expression, enzyme activity and accumulation of defence metabolites. After exposing peppermint (Mentha x piperita L.) plants grown in field (FP) and in a growth chamber (GCP) to UV-B irradiation, we analysed by qRT-PCR the expression of genes involved in terpenoid biosynthesis and encoding: 1-deoxy-D-xylulose-5-phosphate synthase (Dxs), 2-C-methyl-D-erythritol-2,4-cyclodiphosphate synthase (Mds), isopentenyl diphosphate isomerase (Ippi), geranyl diphosphate synthase (Gpps), (-)-limonene synthase (Ls), (-)-limonene-3-hydroxylase (L3oh), (+)-pulegone reductase (Pr), (-)-menthone reductase (Mr), (+)-menthofuran synthase (Mfs), farnesyl diphosphate synthase (Fpps) and a putative sesquiterpene synthase (S-TPS). GCP always showed a higher terpenoid content with respect to FP. We found that in both FP and GCP, most of these genes were regulated by the UV-B treatment. The amount of most of the essential oil components, which were analysed by gas chromatography-mass spectrometry (GC-MS), was not correlated to gene expression. The total phenol composition was found to be always increased after UV-B irradiation; however, FP always showed a higher phenol content with respect to GCP. Liquid chromatography-mass spectrometry (LC-ESI-MS/MS) analyses revealed the presence of UV-B absorbing flavonoids such as eriocitrin, hesperidin, and kaempferol 7-O-rutinoside whose content significantly increased in UV-B irradiated FP, when compared to GCP. The results of this work show that UV-B irradiation differentially modulates the expression of genes involved in peppermint essential oil biogenesis and the content of UV-B absorbing flavonoids. Plants grown in field were better adapted to increasing UV-B irradiation than plants cultivated in growth chambers. The interplay between terpenoid and phenylpropanoid metabolism is also discussed.

  16. Effect of UV-B on enzymes of nitrogen metabolism in the cyanobacterium Nostoc calcicola

    International Nuclear Information System (INIS)

    The effects of ultraviolet-B (UV-B; 280–315 nm) irradiation on nitrogenase and nitrate reductase (NR) activity have been studied in the filamentous and heterocystous N2-fixing cyanobacterium Nostoc calcicola. Exposure of cultures to UV-B (5W/m2) for as little as 30 min caused complete inactivation of nitrogenase activity whereas nitrate reductase activity was stimulated twofold in comparison to one exposed to fluorescent white light. GS activity was also inhibited by UV-B treatment, but there was no total loss of activity even after 4 h. NR activity showed a gradual stimulation up to 4 h and thereafter it became constant. Stimulation was also obtained in reductant deficient cultures (12 h incubation in the dark) suggesting independence of NR of PS-II under UV-B. NR activity was also unaffected in the presence of DCMU, a known inhibitor of PS-II. However, both O2 evolution and 14CO2 uptake were completely abolished following 30 min of UV-B treatment. Addition of the protein synthesis inhibitor chloramphenicol (25 μg/mL) to cultures did not show any inhibitory effect on NR activity. SDS-PAGE analysis of UV-B treated cultures elicited gradual loss of protein bands with increasing duration of exposure. Our findings suggest that UV-B irradiance has differential effects on the enzymes of the nitrogen metabolism in the cyanobacterium Nostoc calcicola. Further studies are needed to reveal the exact mechanism involved in the stimulation of NR activity by UV-B. Whether UV-B has a direct effect on NO2− accumulation in the cells needs detailed investigation. (author)

  17. Photoactivated UVR8-COP1 module determines photomorphogenic UV-B signaling output in Arabidopsis.

    Science.gov (United States)

    Huang, Xi; Yang, Panyu; Ouyang, Xinhao; Chen, Liangbi; Deng, Xing Wang

    2014-03-01

    In Arabidopsis, ultraviolet (UV)-B-induced photomorphogenesis is initiated by a unique photoreceptor UV resistance locus 8 (UVR8) which utilizes its tryptophan residues as internal chromophore to sense UV-B. As a result of UV-B light perception, the UVR8 homodimer shaped by its arginine residues undergoes a conformational switch of monomerization. Then UVR8 associates with the constitutively photomorphogenic 1-suppressor of PHYA (COP1-SPA) core complex(es) that is released from the cullin 4-damaged dna binding protein 1 (CUL4-DDB1) E3 apparatus. This association, in turn, causes COP1 to convert from a repressor to a promoter of photomorphogenesis. It is not fully understood, however, regarding the biological significance of light-absorbing and dimer-stabilizing residues for UVR8 activity in photomorphogenic UV-B signaling. Here, we take advantage of transgenic UVR8 variants to demonstrate that two light-absorbing tryptophans, W233 and W285, and two dimer-stabilizing arginines, R286 and R338, play pivotal roles in UV-B-induced photomorphogenesis. Mutation of each residue results in alterations in UV-B light perception, UVR8 monomerization and UVR8-COP1 association in response to photomorphogenic UV-B. We also identify and functionally characterize two constitutively active UVR8 variants, UVR8W285A and UVR8R338A, whose photobiological activities are enhanced by the repression of CUL4, a negative regulator in this pathway. Based on our molecular and biochemical evidence, we propose that the UVR8-COP1 affinity in plants critically determines the photomorphogenic UV-B signal transduction coupling with UVR8-mediated UV-B light perception.

  18. Photoactivated UVR8-COP1 module determines photomorphogenic UV-B signaling output in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Xi Huang

    2014-03-01

    Full Text Available In Arabidopsis, ultraviolet (UV-B-induced photomorphogenesis is initiated by a unique photoreceptor UV resistance locus 8 (UVR8 which utilizes its tryptophan residues as internal chromophore to sense UV-B. As a result of UV-B light perception, the UVR8 homodimer shaped by its arginine residues undergoes a conformational switch of monomerization. Then UVR8 associates with the constitutively photomorphogenic 1-suppressor of PHYA (COP1-SPA core complex(es that is released from the cullin 4-damaged dna binding protein 1 (CUL4-DDB1 E3 apparatus. This association, in turn, causes COP1 to convert from a repressor to a promoter of photomorphogenesis. It is not fully understood, however, regarding the biological significance of light-absorbing and dimer-stabilizing residues for UVR8 activity in photomorphogenic UV-B signaling. Here, we take advantage of transgenic UVR8 variants to demonstrate that two light-absorbing tryptophans, W233 and W285, and two dimer-stabilizing arginines, R286 and R338, play pivotal roles in UV-B-induced photomorphogenesis. Mutation of each residue results in alterations in UV-B light perception, UVR8 monomerization and UVR8-COP1 association in response to photomorphogenic UV-B. We also identify and functionally characterize two constitutively active UVR8 variants, UVR8W285A and UVR8R338A, whose photobiological activities are enhanced by the repression of CUL4, a negative regulator in this pathway. Based on our molecular and biochemical evidence, we propose that the UVR8-COP1 affinity in plants critically determines the photomorphogenic UV-B signal transduction coupling with UVR8-mediated UV-B light perception.

  19. Effects of UV-B irradiation on growth, survival, pigmentation and nitrogen metabolism enzymes in Cyanobacteria

    International Nuclear Information System (INIS)

    The effects of artificial UV-B irradiation on growth, survival, pigmentation, nitrate reductase (NR), glutamine synthetase (GS) and total protein profile have been studied in a number of N2-fixing cyanobacterial strains isolated from rice (paddy) fields in India. Different organisms show different effects in terms of growth and survival. Complete killing of Anabaena sp. and Nostoc carmium occurs after 120 min of UV-B exposure, whereas the same occurs only after 150 min of exposure in the case of Nostoc commune and Scytonema sp. Growth patterns of the cells treated with UV-B revealed that Nostoc commune and Scytonema sp. are comparatively more tolerant than Anabaena sp. and Nostoc carmium. Pigment content, particularly phycocyanin, was severely decreased following UV-B irradiation in all strains tested so far. In vivo NR activity was found to increase, while in vivo GS activity was decreased following exposure to UV-B for different durations in all test organisms; although complete inhibition of GS activity did not occur even after 120 min of UV-B exposure. (author)

  20. Effects of UV-B irradiation on growth, survival, pigmentation and nitrogen metabolism enzymes in Cyanobacteria

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, R.P.; Hader, D.P. [Institut fuer Botanik und Pharmazeutische Biologie, Friedrich-Alexander Universitaet, Erlangen (Germany); Kumar, H.D.; Kumar, A. [Banaras Hindu University, Varanasi (India)

    1995-12-31

    The effects of artificial UV-B irradiation on growth, survival, pigmentation, nitrate reductase (NR), glutamine synthetase (GS) and total protein profile have been studied in a number of N{sub 2}-fixing cyanobacterial strains isolated from rice (paddy) fields in India. Different organisms show different effects in terms of growth and survival. Complete killing of Anabaena sp. and Nostoc carmium occurs after 120 min of UV-B exposure, whereas the same occurs only after 150 min of exposure in the case of Nostoc commune and Scytonema sp. Growth patterns of the cells treated with UV-B revealed that Nostoc commune and Scytonema sp. are comparatively more tolerant than Anabaena sp. and Nostoc carmium. Pigment content, particularly phycocyanin, was severely decreased following UV-B irradiation in all strains tested so far. In vivo NR activity was found to increase, while in vivo GS activity was decreased following exposure to UV-B for different durations in all test organisms; although complete inhibition of GS activity did not occur even after 120 min of UV-B exposure. (author). 37 refs, 6 figs.

  1. Interaction of the Arabidopsis UV-B-Specific Signaling Component UVR8 with Chromatin

    Institute of Scientific and Technical Information of China (English)

    Catherine Cloix; Gareth I.Jenkins

    2008-01-01

    Arabidopsis UV RESISTANCE LOCUS8 (UVR8) is a UV-B-specific signaling component that regulates expression of a range of genes concerned with UV protection. Here, we investigate the interaction of UVR8 with chromatin. Using antibodies specific to UVR8 in chromatin immunoprecipitation (CHIP) assays with wild-type plants, we show that native UVR8 binds to chromatin in vivo. Similar experiments using an anti-GFP antibody with plants expressing a GFP-UVR8 fusion show that UVR8 associates with a relatively small region of chromatin containing the HY5 gene. UVR8 interacts with chromatin containing the promoter regions of other genes, but not with all the genes it regulates. UV-B is not required for the interaction of UVR8 with chromatin because association with several gene loci is observed in the absence of UV-B. Pulldown assays demonstrate that UVR8 associates with histones in vivo and competition experiments indicate that the interaction is preferentially with histone H2B. ChIP experiments using antibodies that recognize specific histone modifications indicate that the UV-B-stimulated transcription of some genes may be correlated with histone modification. In particular, the ELIP1 promoter showed a significant enrichment of diacetyl histone H3 (K9/K14) following UV-B exposure.These findings increase understanding of the interaction of the key UV-B-specific regulator UVR8 with chromatin.

  2. Effects of enhanced ultraviolet-B radiation on water use efficiency, stomatal conductance, leaf nitrogen content and morphological characteristics of Spiraea pubesoens in a warm-temperate deciduous broad-leaved forest

    Institute of Scientific and Technical Information of China (English)

    CHEN Lan; ZHANG Shouren

    2007-01-01

    Spiraeapubescens,a common shrub in the warm temperate deciduous forest zone which is distributed in the Dongling Mountain area of Beijing,was exposed to ambient and enhanced ultraviolet-B(UV-B,280-320 nm)radiation by artificially supplying a daily dose of 9.4 kJ/m2 for three growing seasons,a level that simulated a 17% depletion in stratospheric ozone.The objective of this study was to explore the effects of long-term UV-B enhancement on stomatal conductance,leaf tissue δ13C,leaf water content,and leaf area.Particular attention was paid to the effects of UV-B radiation on water use efficiency(WUE)and leaf total nitrogen content.Enhanced UV-B radiation significantly reduced leaf area (50.1%)but increased leaf total nitrogen content(102%).These changes were associated with a decrease in stomatal conductance(16.1%)and intercellular CO2 concentration/air CO2 concentration(C/Ca)(4.0%),and an increase in leaf tissue δ13C(20.5%),leaf water content(3.1%),specific leaf weight(SLW)(5.2%)and WUE(4.1%).The effects of UV-B on the plant were greatly affected by the water content of the deep soil(30-40 cm).During the dry season,differences in the stomatat conductance δ13C,and WUE between the control and UV-B treated shrubs were very small;whereas,differences became much greater when soil water stress disappeared.Furthermore,the effects of UV-B became much less significant as the treatment period progressed over the three growing seasons.Correlation analysis showed that enhanced UV-B radiation decreased the strength of the correlation between soil water content and leaf water content, δ13C,Ci/Ca,stomatal conductance,with the exception of WUE that had a significant correlation coefficient with soil water content.These results suggest that WUE would become more sensitive to soil water variation due to UV-B radiation.Based on this experiment,it was found that enhanced UV-B radiation had much more significant effects on morphological traits and growth of S.pubescens than hydro

  3. Combined exposure to ambient UVB radiation and nitrite negatively affects survival of amphibian early life stages

    Energy Technology Data Exchange (ETDEWEB)

    Macias, Guadalupe [Donana Biological Station, CSIC, Spanish Council for Scientific Research. P.O. Box 1056, Sevilla 41013 (Spain); Marco, Adolfo [Donana Biological Station, CSIC, Spanish Council for Scientific Research. P.O. Box 1056, Sevilla 41013 (Spain)], E-mail: amarco@ebd.csic.es; Blaustein, Andrew R. [Department of Zoology, Oregon State University, Corvallis, Oregon, 97331 (United States)

    2007-10-15

    Many aquatic species are sensitive to ambient levels of ultraviolet-B radiation (UVB) and chemical fertilizers. However, recent studies indicate that the interaction among multiple stressors acting simultaneously could be contributing to the population declines of some animal species. Therefore, we tested the potential synergistic effects between ambient levels of UVB and a contaminant, sodium nitrite in the larvae of two amphibian species, the common European toad Bufo bufo and the Iberian green frog Rana perezi. We studied R. perezi from both mountain and coastal populations to examine if populations of the same species varied in their response to stressors in different habitats. Both species were sensitive to the two stressors acting alone, but the interaction between the two stressors caused a multiplicative impact on tadpole survival. For B. bufo, the combination of UVB and nitrite was up to seven times more lethal than mortality for each stressor alone. In a coastal wetland, the combination of UVB and nitrite was four times more toxic for R. perezi than the sum of the effect on mortality for each stressor alone. One mg/L of nitrite killed half the population of R. perezi at Gredos Mountains at day 10 in the absence of UVB. In the presence of UVB, 50% of the tadpoles from the same experiment died at day 7. Similar toxic response were found for R. perezi in two highly contrasted environments suggesting this synergistic interaction can be a widespread phenomenon. The interaction of excess chemical fertilizers and manure with ambient UVB radiation could be contributing to the global decline of some amphibian species. We suggest that potential exposure to UVB radiation be accounted for when assessing water quality criteria regarding nitrite pollution.

  4. Influence of ambient meteorology on the accuracy of radiation measurements: insights from field and laboratory experiments

    Science.gov (United States)

    Oswald, Sandro M.; Pietsch, Helga; Baumgartner, Dietmar J.; Rieder, Harald E.

    2016-04-01

    A precise knowledge of the surface energy budget, which includes the solar and terrestrial radiation fluxes, is needed to accurately characterize the global energy balance which is largely determining Earth's climate. To this aim national and global monitoring networks for surface radiative fluxes have been established in recent decades. The most prominent among these networks is the so-called Baseline Surface Radiation Network (BSRN) operating under the auspices of the World Climate Research Programme (WCRP) (Ohmura et al., 1998). National monitoring networks such as the Austrian RADiation Monitoring Network (ARAD), which has been established in 2010 by a consortium of the Central Agency of Meteorology and Geodynamics (ZAMG), the University of Graz, the University of Innsbruck, and the University of Natural Resources and Applied Sciences, Vienna (BOKU), orient themselves on BSRN standards (McArthur, 2005). ARAD comprises to date five sites (Wien Hohe Warte, Graz/University, Innsbruck/University, Kanzelhöhe Observatory and Sonnblick (which is also a BSRN site)) and aims to provide long-term monitoring of radiation budget components at highest accuracy and to capture the spatial patterns of radiation climate in Austria (Olefs et al., 2015). Given the accuracy requirement for the local monitoring of radiative fluxes instrument offsets, triggered by meteorological factors and/or instrumentation, pose a major challenge in radiation monitoring. Within this study we investigate effects of ambient meteorology on the accuracy of radiation measurements performed with pyranometers contained in various heating/ventilation systems (HV-systems), all of which used in regular operation within the ARAD network. We focus particularly on instrument offsets observed following precipitation events. To quantify pyranometer responses to precipitation we performed a series of controlled laboratory experiments as well as targeted field campaigns in 2015 and 2016. Our results indicate

  5. Effect of UV Radiation and Evaluated CO2 on Morphological Traits, Yield and Yield Components of Canola (Brassica napus L. Grown under Water Deficit Stress

    Directory of Open Access Journals (Sweden)

    Hamid Reza TOHIDI MOGHADAM

    2011-05-01

    Full Text Available In this study, we studied the combined effects of UV radiation, CO2 and water stress on the morphological traits, yield and yield components of canola (Brassica napus cv. �Okapi� and �Talaye� under twelve growth conditions: complete irrigation with ambient CO2 with UV-A (control, complete irrigation with ambient CO2 with UV-B, complete irrigation with ambient CO2 with UV-C, limited irrigation with ambient CO2 with UV-A, limited irrigation with ambient CO2 with UV-B, limited irrigation with ambient CO2 with UV-C, complete irrigation with elevated CO2 with UV-A, complete irrigation with elevated CO2 with UV-B, complete irrigation with elevated CO2 with UV-C, limited irrigation with elevated CO2 with UV-A, limited irrigation with elevated CO2 with UV-B and limited irrigation with elevated CO2 with UV-C. The results showed that water stress significantly decreased all of traits except for the oil percentage. Additionally, an elevated level of CO2 significantly increased the final yield, 1000-seed weight, oil yield, plant height, specific leaf area and number of branches per plant, whereas UV radiation decreased all of the traits in this experiment. Elevated CO2 ameliorated the adverse effects of UV radiation in the final yield, seed weight, oil percentage, oil yield, plant height, specific leaf area and number of branches per plant. This study showed that elevated CO2 can partially ameliorate some of the adverse effects of UV radiation in canola plants. Furthermore, in this study, we observed that the increase in the yield was due to the increase in the seed weight and number of branches caused by elevated CO2 in canola plants. In addition, the maximum yield was obtained from the �Talaye� cultivar under conditions of sunlight, full irrigation and elevated CO2.

  6. Involvement of cathepsin B in mitochondrial apoptosis by p-phenylenediamine under ambient UV radiation.

    Science.gov (United States)

    Goyal, Shruti; Amar, Saroj Kumar; Dubey, Divya; Pal, Manish Kumar; Singh, Jyoti; Verma, Ankit; Kushwaha, Hari Narayan; Ray, Ratan Singh

    2015-12-30

    Paraphenylenediamine (PPD), a derivative of paranitroaniline has been most commonly used as an ingredient of oxidative hair dye and permanent tattoos. We have studied the phototoxic potential of PPD under ambient ultraviolet radiation. PPD is photodegraded and form a novel photoproduct under UV A exposure. PPD shows a concentration dependent decrease in cell viability of human Keratinocyte cells (HaCaT) through MTT and NRU test. Significant intracellular ROS generation was measured by DCFDA assay. It caused an oxidative DNA damage via single stranded DNA breaks, micronuclei and CPD formation. Both lysosome and mitochondria is main target for PPD induced apoptosis which was proved through lysosomal destabilization and release of cathepsin B by immunofluorescence, real time PCR and western blot analysis. Cathepsin B process BID to active tBID which induces the release of cytochrome C from mitochondria. Mitochondrial depolarization was reported through transmission electron microscopy. The cathepsin inhibitor reduced the release of cytochrome C in PPD treated cells. Thus study suggests that PPD leads to apoptosis via the involvement of lysosome and mitochondria both under ambient UV radiation. Therefore, photosensitizing nature of hair dye ingredients should be tested before coming to market as a cosmetic product for the safety of human beings. PMID:26223015

  7. 紫外辐射对灯盏花附生、内生细菌数量的影响及机理%Effects of UV-B radiation on quantity of epiphytic bacteria, endophytic bacteria and physiological mechanism of Erigeron breviscapus

    Institute of Scientific and Technical Information of China (English)

    宣灵; 何永美; 湛方栋; 张丽梅; 祖艳群; 李元

    2009-01-01

    采用大田研究方法,模拟5.0kJ·m~(-2)紫外辐射(UV-B,280~315nm)增强对灯盏花Erigeronbreviscapus附生、内生细菌数量、优势种群以及类黄酮、游离氨基酸、可溶性蛋白、淀粉和可溶性糖含量的影响.UV-B辐射极显著减少灯盏花苗期叶和花期根与叶附生细菌数量(p<0.01),显著减少灯盏花果熟期根与叶附生细菌数量(p<0.05).极显著减少灯盏花苗期根与叶和花期叶与茎及果熟期茎内生细菌的数量,果熟期根内生细菌数量显著增加.灯盏花附生细菌优势种群为芽孢杆菌Bacillus和欧文氏菌Erwinia,内生细菌优势种群为芽孢杆菌;UV-B辐射可导致灯盏花附生和内生细菌优势种群数目减少.UV-B辐射还会使灯盏花生理指标发生变化,直接导致灯盏花附生细菌数量的减少,可溶性糖、游离氨基酸和可溶性蛋白含量与附生细菌数量呈显著正相关(p<0.05).UV-B辐射增加灯盏花各部位类黄酮含量,间接影响灯盏花内生细菌数量,根类黄酮含量与内生细菌数量呈极显著正相关(p<0.01).

  8. 金龟子绿僵菌诱发UV-B抗性导致分生孢子产孢和孢子逆境耐受性的转化%Inducing UV-B tolerance of Metarhizium anisopliae var.anisopliae conidia results in a trade-off between conidial production and conidial stress tolerance

    Institute of Scientific and Technical Information of China (English)

    德罗奇欧· 兰格尔; Donald W Roberts

    2007-01-01

    The conidial tolerance of Metarhizium anisopliae var.anisopliae isolate ARSEF 2575 to UV-B irradiation is greatly influenced by growth-environment alterations. In this review, we report high variability in conidial UV-B tolerance in response to altered culture conditions.Conidia produced on insect cadavers[Zophobas morio(Coleoptera) or Galleria mellonella(Lepidoptera)] had low tolerance to UV-B radiation; and conidia produced on potato dextrose agar supplemented with yeast extract (PDAY) had medium UV-B tolerance; whereas conidia produced on a minimal medium without any carbon source (MM), on MM with a non-preferred carbon source such as lactose (=MML), on PDAY plus 1 M NaCl or KCl, or PDBY with high alkalinity had the highest UV-B tolerances. All of the above conditions that induced high UV-B tolerance, however, also greatly reduced conidial production. Comparisons between stress tolerance and conidial production, particularly with conidia produced under osmotic and nutritive stress, point out that the benefits of producing very tolerant conidia have the enormous cost of low conidial production. Growth under visible light also greatly improved conidial UV-B tolerance, but light did not negatively influence conidial production. Therefore, culture on rich media under light is proposed as the most promising approach to producing conidia with improved UV-B tolerance for biological control of pest insects in agriculture.

  9. Pectins, ROS homeostasis and UV-B responses in plant roots.

    Science.gov (United States)

    Yokawa, Ken; Baluška, František

    2015-04-01

    Light from the sun contains far-red, visible and ultra violet (UV) wavelength regions. Almost all plant species have been evolved under the light environment. Interestingly, several photoreceptors, expressing both in shoots and roots, process the light information during the plant life cycle. Surprisingly, Arabidopsis root apices express besides the UVR8 UV-B receptor, also root-specific UV-B sensing proteins RUS1 and RUS2 linked to the polar cell-cell transport of auxin. In this mini-review, we focus on reactive oxygen species (ROS) signaling and possible roles of pectins internalized via endocytic vesicle recycling system in the root-specific UV-B perception and ROS homeostasis.

  10. Standard UV-B irradiation of platelets concentrates to prevent from PT-GVHD for alloimmunization

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Takayoshi [Toranomon Hospital, Tokyo (Japan); Nagahashi, Hisakata; Takenouchi, Kogi; Tayama, Tatsuya; Tadokoro, Kenji; Juji, Takeo

    1994-11-01

    We tried to make an appropriate standard condition for UV-B irradiation of platelets concentrates (PC), which is useful for prophylaxis against post-transfusion graft versus host disease (PT-GVHD) as well as prevention against alloimmunization. Agitation of PC bags during UV-B irradiation is necessary to irradiate evenly cells in the bag, because a lot of UV-B ray should be absorbed by bag membrane and plasma. Amounts of UV-B that each lymphocyte or platelet would actually receive on an average (UVavg) was calculated by the equation as below. UV{sup *}avg=K{sub 1} x (K{sub 2}{sup L} - 1) x UV/(log{sub e}K{sub 2} x L), K{sub 1} and K{sub 2} are permeability index of bag membrane and that in plasma, respectively; while L and UV stands for depth of PC bag and emitting dose of UV-B, respectively. We irradiated PC bags with UV-B in a dose of 541-13,525 J/m{sup 2} of UV{sup *}avg, and examined lymphocytes in the bags about the responder and stimulator activities in mixed lymphocytes culture (MLR), as well as platelet function in the bags. Irradiation more than 5,000 J/m{sup 2} of UV{sup *}avg is needed to suppress responder and stimulator activities, and platelet function is maintained up to 13,525 J/m{sup 2} of UV{sup *}avg. In conclusion, UV-irradiation in a range of 6,000-13,000 J/m{sup 2} of UV{sup *}avg is considered appropriate to prevent from RT-GVHD or alloimmunization. (author).

  11. Influence of solar UV radiation on the nitrogen metabolism in needles of Scots pine (Pinus sylvestris L.)

    Energy Technology Data Exchange (ETDEWEB)

    Krywult, Marek [Department of Instrumental Analysis, Provincial Sanitary-Epidemiological Station, State Sanitary Inspection, Pradnicka 76, PL-31-202 Krakow (Poland)], E-mail: marasek2@gazeta.pl; Smykla, Jerzy [Department of Biodiversity, Institute of Nature Conservation, Polish Academy of Sciences, Mickiewicza 33, PL-31-120 Krakow (Poland)], E-mail: smykla@iop.krakow.pl; Kinnunen, Heli [Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi (Finland)], E-mail: heli.kinnunen@gmail.com; Martz, Francoise [Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi (Finland)], E-mail: francoise.martz@metla.fi; Sutinen, Marja-Liisa [Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi (Finland); Department of Biology, University of Oulu, P.O. Box 3000, FI-90014 (Finland)], E-mail: marja-liisa.sutinen@metla.fi; Lakkala, Kaisa [Arctic Research Centre, Finnish Meteorological Institute (FMI-ARC), Taehtelaentie 62, FI-99600 Sodankylae (Finland)], E-mail: kaisa.lakkala@fmi.fi; Turunen, Minna [Arctic Centre, University of Lapland, POB 122, FI-96101 Rovaniemi (Finland)], E-mail: minna.turunen@ulapland.fi

    2008-12-15

    Needles of 20-year-old Scots pine (Pinus sylvestris L.) saplings were studied in an ultraviolet (UV) exclusion field experiment (from 2000 to 2002) in northern Finland (67 deg. N). The chambers held filters that excluded both UV-B and UV-A, excluded UV-B only, transmitted all UV (control), or lacked filters (ambient). UV-B/UV-A exclusion decreased nitrate reductase (NR) activity of 1-year-old needles of Scots pines compared to the controls. The proportion of free amino acids varied in the range 1.08-1.94% of total proteins, and was significantly higher in needles of saplings grown under UV-B/UV-A exclusion compared to the controls or UV-B exclusion. NR activity correlated with air temperature, indicating a 'chamber effect'. The study showed that both UV irradiance and increasing temperature are significant modulators of nitrogen (N) metabolism in Scots pine needles. - This research presents new information on the responses of N metabolism, particularly nitrate reductase (NR) activity, of Scots pine needles to UV radiation and temperature.

  12. Flavonoids Derived from Abelmoschus esculentus Attenuates UV-B Induced Cell Damage in Human Dermal Fibroblasts Through Nrf2-ARE Pathway

    Science.gov (United States)

    Patwardhan, Juilee; Bhatt, Purvi

    2016-01-01

    Background: Ultraviolet-B (UV-B) radiation is a smaller fraction of the total radiation reaching the Earth but leads to extensive damage to the deoxyribonucleic acid (DNA) and other biomolecules through formation of free radicals altering redox homeostasis of the cell. Abelmoschus esculentus (okra) has been known in Ayurveda as antidiabetic, hypolipidemic, demulscent, antispasmodic, diuretic, purgative, etc. Objective: The aim of this study is to evaluate the protective effect of flavonoids from A. esculentus against UV-B-induced cell damage in human dermal fibroblasts. Materials and Methods: UV-B protective activity of ethyl acetate (EA) fraction of okra was studied against UV-B-induced cytotoxicity, antioxidant regulation, oxidative DNA damage, intracellular reactive oxygen species (ROS) generation, apoptotic morphological changes, and regulation of heme oxygenase-1 (HO-1) gene through nuclear factor E2-related factor 2-antioxidant response element (Nrf2-ARE) pathway. Results: Flavonoid-rich EA fraction depicted a significant antioxidant potential also showing presence of rutin. Pretreatment of cells with EA fraction (10–30 μg/ml) prevented UV-B-induced cytotoxicity, depletion of endogenous enzymatic antioxidants, oxidative DNA damage, intracellular ROS production, apoptotic changes, and overexpression of Nrf2 and HO-1. Conclusion: Our study demonstrated for the 1st time that EA fraction of okra may reduce oxidative stress through Nrf2-ARE pathway as well as through endogenous enzymatic antioxidant system. These results suggested that flavonoids from okra may be considered as potential UV-B protective agents and may also be formulated into herbal sunscreen for topical application. SUMMARY Flavonoid-enriched ethyl acetate (EA) fraction from A. esculentus protected against ultraviolet-B (UV-B)-induced oxidative DNA damageEA fraction prevented UV-B-induced cytotoxicity, depletion of endogenous enzymatic antioxidants, and intracellular reactive oxygen species

  13. Non-contact skin emissivity: measurement from reflectance using step change in ambient radiation temperature.

    Science.gov (United States)

    Togawa, T

    1989-02-01

    A method of estimating skin emissivity based on reflectance measurement upon transient stepwise change in the ambient radiation temperature was proposed. To effect this change, two shades at different temperatures were switched mechanically, and the change in radiation from the skin surface was recorded through an aperture for each shade by a high-resolution, fast-response radiometer having a sensitivity within the 8-14 microns range. Measurements were made on the forehead, forearm, palm and back of the hand in 10 male and 10 female subjects. No significant differences in emissivity were observed among sites and between sexes. The overall average of the skin emissivity obtained was 0.971 +/- 0.005 (SD). This result is inconsistent with most reported skin emissivity values. However, as the former studies had many inherent inadequacies, both theoretical and experimental, it is considered that most of these reported skin emissivities are unacceptable. The method proposed in this study has the following advantages: (1) relative calibration between instruments is unnecessary, (2) non-contact measurement can be achieved, and (3) each measurement can be made within one minute.

  14. Influence of Solar Radiation and Biotic Interactions on Bacterial and Eukaryotic Communities Associated with Sewage Decomposition in Ambient Water - Poster

    Science.gov (United States)

    Sewage and ambient water both consist of a highly complex array of bacteria and eukaryotic microbes. When these communities are mixed, the persistence of sewage-derived pathogens in environmental waters can represent a significant public health concern. Solar radiation and biotic...

  15. Influence of solar radiation and biotic interactions on bacterial and eukaryotic communities associated with sewage decomposition in ambient water

    Science.gov (United States)

    Sewage and ambient water both consist of a highly complex array of bacteria and eukaryotic microbes. When these communities are mixed, the persistence of sewage-derived pathogens in environmental waters can represent a significant public health concern. Solar radiation and biot...

  16. Ocean acidification mediates photosynthetic response to UV radiation and temperature increase in the diatom Phaeodactylum tricornutum

    Directory of Open Access Journals (Sweden)

    E. W. Helbling

    2012-10-01

    Full Text Available Increasing atmospheric CO2 concentration is responsible for progressive ocean acidification, ocean warming as well as decreased thickness of upper mixing layer (UML, thus exposing phytoplankton cells not only to lower pH and higher temperatures but also to higher levels of solar UV radiation. In order to evaluate the combined effects of ocean acidification, UV radiation and temperature, we used the diatom Phaeodactylum tricornutum as a model organism and examined its physiological performance after grown under two CO2 concentrations (390 and 1000 μatm for more than 20 generations. Compared to the ambient CO2 level (390 μatm, growth at the elevated CO2 concentration increased non-photochemical quenching (NPQ of cells and partially counteracted the harm to PS II (photosystem II caused by UV-A and UV-B. Such an effect was less pronounced under increased temperature levels. The ratio of repair to UV-B induced damage decreased with increased NPQ, reflecting induction of NPQ when repair dropped behind the damage, and it was higher under the ocean acidification condition, showing that the increased pCO2 and lowered pH counteracted UV-B induced harm. As for photosynthetic carbon fixation rate which increased with increasing temperature from 15 to 25 °C, the elevated CO2 and temperature levels synergistically interacted to reduce the inhibition caused by UV-B and thus increase the carbon fixation.

  17. Characterization of clouds and aerosols by lidar remote sensing with regard to the transfer of UV radiation. Final report; Leitthema 4: Solare UV-B-Strahlung. Teilvorhaben: Charakterisierung von Wolken und Aerosolen durch Lidar-Fernerkundung hinsichtlich des UV-Strahlungstransfers. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, H.; Muecke, R.; Kreipl, S.

    2000-05-01

    The investigations characterize aerosols and clouds over Garmisch-Partenkirchen by lidar remote sensing, and support the interpretation of measurements of the transfer of UV radiation. Extensive tests of calibration procedures were performed, and the lidar system was modified to meet the requirements. The focal point were measurements accompanying the CUVRA (Characteristics of the UV Radiation field in the Alps) campaign at IFU in March 1999. 767 lidar measurements in two wavelength channels were performed on 12 days during this campaign. Aerosol and cloud situations were characterized by determining lower and upper layer heights (time resolution down to 1 minute, height resolution down to 15 meters), multi layer situations from ground to the tropopause region (up to 5 aerosol and cloud layers), optical depths at 532 nm and 355 nm (range 0.01 to 3), wavelength dependences of the optical depth between 532 nm and 355 nm (range of wavelength exponent 0 to -2), and lidar ratios (extinction/backscatter) at 532 nm (range 20 to 38). (orig.) [German] Die Untersuchungen charakterisieren Aerosole und Wolken ueber Garmisch-Partenkirchen durch Lidar-Fernerkundung und dienen der Interpretation von Messungen des UV-Strahlungsflusses. Hierzu waren umfangreiche Arbeiten zum Testen von Eichverfahren notwendig, ebenso wie Modifizerungen des Lidarsystems. Schwerpunkt der Untersuchungen waren Messungen waehrend der CUVRA (Characteristics of the UV Radiation field in the Alps) Messkampagne im Maerz 1999 am IFU. Waehrend dieser Kampagne wurden an 12 Messtagen 767 Lidarmessungen in jeweils zwei Wellenlaengenkanaelen durchgefuehrt. Die Aerosol- und Wolkensituationen wurden charakterisiert durch die Bestimmung von Schichtunter- und obergrenzen (Zeitaufloesung bis zu 1 Minute, Hoehenaufloesung bis zu 15 m), der Mehrschichtigkeit vom Boden bis zum Tropopausenbereich (bis zu 5 Aerosol- und Wolkenschichten), der optischen Dicken bei 532 nm und 355 nm (Bereich 0.01 bis 3), der

  18. Distribution of Boreal Toad Populations in Relation to Estimated UV-B Dose in Glacier National Park, Montana, USA

    Science.gov (United States)

    This work provides information on amphibian distributions as well as the range of UV-B exposure in mountain habitats, and will be of use to scientists interested in tracking changes in amphibian distributions and abundance, and spatial and temporal patterns of UV-B exposure

  19. UV-B辐射对黄化番茄幼苗生长及光合作用的影响%Effects of UV-B on growth and photosynthesis in etiolating type tomato seedling

    Institute of Scientific and Technical Information of China (English)

    胡志峰; 郁继华

    2014-01-01

    以黄化番茄和普通番茄幼苗为试材,研究UV-B辐射对番茄幼苗生长和光合作用的影响.结果表明:UV-B辐射处理对番茄幼苗株高、茎粗、叶片的抑制作用非常明显,且对叶绿素破坏严重,导致幼苗光合速率降低,类黄酮含量升高10%以上.UV-B处理后两种番茄生长都受到明显抑制,但以黄化苗的变化更为明显,表明黄化番茄幼苗对 UV-B辐射更为敏感.%The effect of UV-B on the growth and photosynthesis in etiolating type and the normal toma-to seedling were studied.The results showed that the plant height,stem diameter and leaf size of the two kinds of tomato seedlings were inhibited by UV-B radiation.The UV-B radiation caused great damage of chlorophyll and decrease in photosynthetic rate (Pn ).The flavonoid content increased considerably under UV-B radiation.The changes of the etiolating type were more distinctly.It is indicated that the etiolating type is more sensitive than the normal tomato to UV-B radiation.

  20. Simulation of increasing UV radiation as a consequence of ozone depletion

    Science.gov (United States)

    Diaz, Susana B.; Camilion, Carolina; Lacoste, Karine; Escobar, Julio; Demers, Serge; Gianesella, Sonia M. F.; Roy, Suzanne

    2003-11-01

    UV plays a key roll in several biological functions. As consequence of the ozone depletion investigations to study the effects of UV radiation on human health and terrestrial and aquatic ecosystems have been carried out in laboratories and in the field. Experiments performed in laboratories, irradiating samples with lamps often present the inconvenience that light sources do not reproduce properly the solar spectrum. Field experiments are usually carried out comparing samples exposed to ambient irradiance (normal or increased) against 100% UV-B screened samples. This scenario also differs from the real situation of normal irradiance against UV-B increased irradiance. Some authors have solved this problem performing studies under ambient conditions, simulating the ozone depletion by supplementation of the UV-B radiation with lamps. As part of the IAI CNR-26, "Enhanced Ultraviolet-B Radiation in Natural Ecosystems as an added Perturbation due to Ozone Depletion," mesocosms experiments were performed at Rimouski, Canada), Ubatuba (Brasil) and Ushuaia, Argentina) using the supplementing methodology. In this paper we introduce the design of the measurements and lamps setting and the methodology used to calculate the attenuation constant and the irradiance at the water column at the mesocosms during the experiment, emphasizing on the Ubatuba campaign.

  1. Soybean rhizosphere soil parameters in response to enhanced UV-B radia-tion under field condition%大田条件下UV-B辐射增强对大豆根际土壤相关指标的影响

    Institute of Scientific and Technical Information of China (English)

    张令瑄; 谢婷婷; 王瑾; 张文会; 吕志伟

    2016-01-01

    Soybean variety Xihuang 27 was exposed to enhanced UV⁃B radiation, under field condition, and rhizo⁃sphere soil parameters including soil microorganisms, content of organic matter, total nitrogen, activities of soil urease and invertase were measured during soybean development. At branching period, flowering period and seed⁃filling period, en⁃hanced UV⁃B radiation significantly inhibited the activities of soil urease by 17�9%, 11�7% and 5�7%, respectively and invertase by 23�5%, 6�1% and 13�2%, respectively. The amount of bacteria was deereased by 40�1%, 38�2% and 26�1%, respectively and the amount of aerobic azotobacter dropped by 72�2%, 33�3% and 35�7%, respectively. The a⁃mount of actinomycete was decreased by 36�3% and 50�0% only at branching and flowering whereas the amount of fungi was significantly decreased by 59�0% only at branching. No significant inhibition was found on the content of organic matter and total nitrogen. In conclusion, enhanced UV⁃B radiation could reduce the amounts of rhizosphere soil microorganisms and soil enzyme activities.%为了研究UV⁃B辐射增强对田间大豆根际土壤相关指标的影响,在大田条件下,通过模拟UV⁃B辐射增强,对大豆根际土壤微生物数量、根际土壤有机质含量、总氮含量以及根际土壤脲酶和转化酶酶活性进行测定。结果表明,在分枝期、花期及鼓粒期,UV⁃B辐射增强使脲酶的活性分别下降17�9%、1�7%和5�7%;转化酶的活性分别下降23�5%、6�1%和13�2%;细菌的数量显著降低40�1%、38�2%和26�1%;好氧固氮菌的数量显著降低72�2%、33�3%和35�7%。放线菌的数量只在分枝期和花期显著降低36�3%和50�0%,真菌的数量只在分枝期显著降低;UV⁃B辐射增强对土壤有机质、总氮含量没有显著影响。说明UV⁃B辐射增强可对大豆根际微生物的数量及土壤酶的活

  2. Effect of UV-B irradiation on interspecific competition between Ulva pertusa and Grateloupia filicina

    Institute of Scientific and Technical Information of China (English)

    李丽霞; 张培玉; 赵吉强; 周文礼; 唐学玺

    2010-01-01

    We report the effect of UV-B irradiation(9.6 kJ m-2day-1)on interspecific competition between two species of macroalgae,Ulva pertusa(U)and Grateloupia filicina(G),in co-culture.Growth of U.pertusa and G.filicina was inhibited by UV-B irradiation in mono-culture and specific growth rate (μ)declined as a result.Interspecific competition between U.pertusa and G.filicina was closely related to the initial weights when co-cultured.When initial ratios of U.pertusa(U)to G.filicina(G)were U:G=1.2:1 and 1:1,U.pertus...

  3. Expression profiling of human melanocytes in response to UV-B irradiation

    Directory of Open Access Journals (Sweden)

    Saioa López

    2015-12-01

    Full Text Available A comprehensive gene expression analysis of human melanocytes was performed assessing the transcriptional profile of dark melanocytes (DM and light melanocytes (LM at basal conditions and after UV-B irradiation at different time points (6, 12 and 24 h, and in culture with different keratinocyte-conditioned media (KCM+ and KCM−. The data, previously published in [1], have been deposited in NCBI's Gene Expression Omnibus (GEO accession number: GSE70280.

  4. 细胞内IP3-Ca2+途径对UV-B辐射下玉米幼苗光合特性的调控机制%Regulation Mechanism of Intracellular IP3-Ca2+ on Photosynthesis in Maize Seedlings under UV-B Stress

    Institute of Scientific and Technical Information of China (English)

    吴能表; 洪鸿

    2013-01-01

      使用外加0.15 W m−2 UV-B及不同钙效应剂处理玉米幼苗,研究细胞Ca2+信号系统对UV-B辐射下玉米幼苗光合作用的调控机制.结果表明, UV诱导的胞内Ca2+荧光增强受胞内IP3通道阻断剂肝素(Heparin)、胞内CaM活性抑制剂三氟啦嗪(TFP)抑制,降低玉米幼苗Chl a、Chl b及Chl a+b含量、原初光能转化效率(Fv/Fm)、PSII活性(Fv/Fo)、Hill 反应活力、水分利用效率(WUE),提高胞间二氧化碳浓度(Ci),最终导致净光合速率(Pn)下降;细胞质膜钙通道阻断剂氯化镧(LaCl3)引发的此效应较小.据此提出, UV-B辐射下,玉米幼苗叶片细胞IP3动员胞内钙库释放Ca2+,调节光合色素合成、Hill反应活性、WUE, CaM介导的下游反应调节Gs,是Ca2+信号系统最终实现对Pn调控的主要机制.%UV-B radiation is one of the main adverse environmental factors, obviously affecting plants’ growth and development. Calciumion, as the second messenger in cell signal transduction system, mediates a series of physiological and biochemical reac-tions, which is helpful to alleviate the damage from adverse environmental factors. To investigate the regulational relation be-tween calcium signal system and UV-B radiation in maize, we studied the effects of calcium signal on photosynthesis in maize (Zea mays L.) seedlings under UV-B stress.With the treatments of seedlings growing in natural condition (CK), 0.15 W m−2 UV-B radiation (UV-B), 0.15 W m−2 UV-B radiation+Heparin (UV-B+H), 0.15 W m−2 UV-B radiation+Trifluoperzine (UV-B+TFP), 0.15 W m−2 UV-B radiation+LaCl3 (UV-B+LaCl3), 0.15 W m−2 UV-B radiation+CaCl2 (UV-B+CaCl2), respectively. The Ca2+fluorescence intensity increased rapidly when it was treated with UV-B. However, when the maize leaves were treated with Hepa-rin (intracellular IP3 channel blocker) and Trifluoperazine (intracellular CaM activity inhibitor), the increase of Ca2+fluorescence intensity was inhibited in the mean time, chlorophyll

  5. UV-B stress induced metabolic rearrangements explored with comparative proteomics in three Anabaena species.

    Science.gov (United States)

    Shrivastava, Alok Kumar; Chatterjee, Antra; Yadav, Shivam; Singh, Prashant Kumar; Singh, Shilpi; Rai, L C

    2015-09-01

    Comparative proteomics together with physiological variables revealed different responses among three species of diazotrophic cyanobacterium Anabaena exposed to UV-B stress at the same time points. Perceptible decline in PSII activity, ATP pool, nitrogenase activity and respiration rate was observed for all the three species; this being maximum in Anabaena doliolum, followed by Anabaena sp. PCC 7120 and minimum in Anabaena L31. Statistical analysis of the protein abundance divided majority of them as early accumulated in A. L31, late accumulated in A. sp. PCC 7120 and downregulated in A. doliolum. Tolerance of A. L31 may be ascribed to post-translational modification reflected through the highest number of protein isoforms in its proteome followed by A. PCC 7120 and A. doliolum. Furthermore, increase in abundance of cyanophycinase, glutamine synthetase and succinate semialdehyde dehydrogenase in A. L31 suggests operation of an alternate pathway for assimilation of nitrogen and carbon under UV-B stress. An early accumulation of four proteins viz., glutamate ammonia ligase (Alr2328), transketolase (Alr3344), inorganic pyrophosphatase (All3570), and trigger protein (Alr3681) involved respectively in amino acid metabolism, energy metabolism, biosynthesis of cofactor and trigger protein and chaperone like activity across three species, suggests them to be marker of UV-B stress in Anabaena spp. This article is part of a Special Issue entitled: Proteomics in India.

  6. Enhanced DNA repair of cyclobutane pyrimidine dimers changes the biological response to UV-B radiation

    Energy Technology Data Exchange (ETDEWEB)

    Yarosh, Daniel B

    2002-11-30

    The goal of DNA repair enzyme therapy is the same as that for gene therapy: to rescue a defective proteome/genome by introducing a substitute protein/DNA. The danger of inadequate DNA repair is highlighted in the genetic disease xeroderma pigmentosum. These patients are hypersensitive to sunlight and develop multiple cutaneous neoplasms very early in life. The bacterial DNA repair enzyme T4 endonuclease V was shown over 25 years ago to be capable of reversing the defective repair in xeroderma pigmentosum cells. This enzyme, packaged in an engineered delivery vehicle, has been shown to traverse the stratum corneum, reach the nuclei of living cells of the skin, and enhance the repair of UV-induced cyclobutane pyrimidine dimers (CPD). In such a system, changes in DNA repair, mutagenesis, and cell signaling can be studied without manipulation of the genome.

  7. UV-B radiation affects plant volatile emissions and shade avoidance responses

    NARCIS (Netherlands)

    Gankema, P.

    2015-01-01

    Plants detect and integrate an assortment of signals from their environment, and use these signals to maximise their performance by adjusting their growth and development as well as their secondary metabolite production. In this thesis, we investigated how plants integrate visual and olfactory signa

  8. Increase of vitamin D2 by UV-B exposure during the growth phase of white button mushroom (Agaricus bisporus

    Directory of Open Access Journals (Sweden)

    Hanne L. Kristensen

    2012-04-01

    Full Text Available Background: Mushrooms are the only non-animal food source of vitamin D. Wild mushrooms have naturally high vitamin D2 content, and cultivated mushrooms produce vitamin D2 from ergosterol when exposed to supplementary UV-B during the post-harvest phase.Objectives: This study investigated the effects of providing supplementary UV-B during the growth phase on vitamin D2 formation and the interactions with growth of mushrooms, as compared to supplementary UV-B during the post-harvest phase or exposure to sunlight for both cultivated and wild mushrooms.Methods: Experiments were carried out with exposure to supplementary UV-B just prior to harvest in the range of 0–2,400 mJ cm−2. Mushrooms grew for 2 days with or without repeated UV-B exposure each day. Vitamin D2 and growth rate were determined. In addition, some mushrooms were post-harvest treated by exposure at 200 mJ cm−2 supplementary UV-B or natural sunlight, prior to vitamin D2 determination.Results: The content of vitamin D2 was 0.2–164 µg 100 g−1 fresh weight, and there was a linear relationship between UV-dose up to 1,000 mJ cm−2 and vitamin D2 content. The fast growth rate of the mushrooms diluted the vitamin D2 from 24 to 3 µg 100 g−1 within 2 days of exposure at 200 mJ cm−2. Following repeated UV-B exposure, vitamin D2 increased to 33 µg vitamin D2 100 g−1. Growth was unaffected by UV-B. Post-harvest exposure to supplementary UV-B resulted in a higher vitamin D2 content of 32 µg 100 g−1 compared to the 24 µg 100 g−1 obtained from exposure to UV-B during the growth phase. In contrast, wild and cultivated mushrooms with and without exposure to sunlight had vitamin D2 content in the range of 0.2–1.5 µg vitamin D2 100 g−1.Conclusions: This study showed that mushrooms with a well-defined content of vitamin D2 can be obtained by exposure to supplementary UV-B just prior to harvest.

  9. Evidence of a possible turning point in solar UV-B over Canada, Europe and Japan

    Directory of Open Access Journals (Sweden)

    C. S. Zerefos

    2012-03-01

    Full Text Available This study examines the long-term variability of UV solar irradiances at 305 nm and 325 nm over selected sites in Canada, Europe and Japan. Site selection was restricted to the availability of the most complete UV spectroradiometric datasets during the period 1990–2011. The analysis includes the long-term variability of total ozone, aerosol optical depth and cloud fraction at the sites studied. The results, based on observations and modeling, suggest that over Canada, Europe and Japan the period under study can be divided into three sub-periods of scientific merit: the first period (1991–1994 is the period perturbed by the Pinatubo volcanic eruption, during which excess volcanic aerosol has enhanced the "conventional" amplification factor of UV-B at ground level by an additional factor that depends on solar elevation. The increase of the UV-B amplification factor is the result of enhanced scattering processes caused by the injection of huge amounts of volcanic aerosols during the perturbed period. The second period (1995–2006 is characterized by a 0.14% yr−1 increase in total ozone and an increasing trend in spectral irradiance by 0.94% yr−1 at 305 nm and 0.88% yr−1 at 325 nm. That paradox was caused by the significant decline of the aerosol optical depth by more than 1% yr−1 (the "brightening" effect and the absence of any statistically significant trend in the cloud fraction. The third period (2007–2011 shows statistically significant evidence of a slowdown or even a turning point in the previously reported upward UV-B trends over Canada, Europe and Japan.

  10. Effects of UV-B on activities of enzymes of secondary phenolic metabolism in barley primary leaves

    International Nuclear Information System (INIS)

    Barley (Hordeum vulgare L.) was grown in a glasshouse with 13.56 or 8.84 kJ m−2: biologically effective UV-B (280–320 nm: UV-BBE) simulating levels predicted to occur with 25 or 5% ozone depletion at 40°N latitude, with UV-A (320–400 mm), or with no supplemental irradiation. Activities of L-phenylalanine ammonia-lyase (PAL, EC 4.3.1.5). chalcone-flavanone isomerase (CFI, EC 5.5.1.6) and peroxidase (EC 1.11.1.7) were determined from the 5th through the 30th day after planting. PAL regulates diversion of L-phenylalanine into precursors for secondary phenolics. CFI regulates an early step of flavonoid biosynthesis, and peroxidase activates phenolic precursors for cross-linking and rigidifying cell walls. At all ages UV-B decreased soluble protein leaf−1 but had little effect on fresh weight or CFI activity. Exposure to UV-B decreased peroxidase activity only slightly in early growth stages but decreased it about 40% by day 30. PAL activity was highest 5 days after planting under all treatments, decreased thereafter, and was not detectable in control plants after day 10. UV-B prolonged PAL activity through day 15 in plants given the highest level of UV-B. This UV-B prolongation of PAL activity is correlated with, and is a likely underlying mechanism to explain, the UV-B- enhanced accumulation of flavonoids and ferulic acid in barley primary leaves. The results are discussed in terms of barley leaf adaptation to UV-B as developmental response dependent on conditions of plant growth. (author)

  11. Efficient Rutin and Quercetin Biosynthesis through Flavonoids-Related Gene Expression in Fagopyrum tataricum Gaertn. Hairy Root Cultures with UV-B Irradiation.

    Science.gov (United States)

    Huang, Xuan; Yao, Jingwen; Zhao, Yangyang; Xie, Dengfeng; Jiang, Xue; Xu, Ziqin

    2016-01-01

    Transformed hairy roots had been efficiently induced from the seedlings of Fagopyrum tataricum Gaertn. due to the infection of Agrobacterium rhizogenes. Hairy roots were able to display active elongation with high root branching in 1/2 MS medium without growth regulators. The stable introduction of rolB and aux1 genes of A. rhizogenes WT strain 15834 into F. tataricum plants was confirmed by PCR analysis. Besides, the absence of virD gene confirmed hairy root was bacteria-free. After six different media and different sources of concentration were tested, the culturing of TB7 hairy root line in 1/2 MS liquid medium supplemented with 30 g l(-1) sucrose for 20 days resulted in a maximal biomass accumulation (13.5 g l(-1) fresh weight, 1.78 g l(-1) dry weight) and rutin content (0.85 mg g(-1)). The suspension culture of hairy roots led to a 45-fold biomass increase and a 4.11-fold rutin content increase in comparison with the suspension culture of non-transformed roots. The transformation frequency was enhanced through preculturing for 2 days followed by infection for 20 min. The UV-B stress treatment of hairy roots resulted in a striking increase of rutin and quercetin production. Furthermore, the hairy root lines of TB3, TB7, and TB28 were chosen to study the specific effects of UV-B on flavonoid accumulation and flavonoid biosynthetic gene expression by qRT-PCR. This study has demonstrated that the UV-B radiation was an effective elicitor that dramatically changed in the transcript abundance of ftpAL, FtCHI, FtCHS, FtF3H, and FtFLS-1 in F. tataricum hairy roots. PMID:26870075

  12. Efficient rutin and quercetin biosynthesis through flavonoids-related gene expression in Fagopyrum tataricum Gaertn hairy root cultures with UV-B irradiation

    Directory of Open Access Journals (Sweden)

    Xuan eHuang

    2016-02-01

    Full Text Available Transformed hairy roots had been efficiently induced from the seedlings of Fagopyrum tataricum Gaertn. due to the infection of Agrobacterium rhizogenes. Hairy roots were able to display active elongation with high root branching in 1/2 MS medium without growth regulators. The stable introduction of rolB and aux1 genes of A. rhizogenes WT strain 15834 into F. tataricum plants was confirmed by PCR analysis. Besides, the absence of virD gene confirmed hairy root was bacteria-free. After 6 different media and different sources of concentration were tested, the culturing of TB7 hairy root line in 1/2 MS liquid medium supplemented with 30 g•l-1 sucrose for 20 days resulted in a maximal biomass accumulation (13.5 g•l-1 fresh weight, 1.78 g•l-1 dry weight and rutin content (0.85 mg•g-1. The suspension culture of hairy roots led to a 45-fold biomass increase and a 4.11-fold rutin content increase in comparison with the suspension culture of non-transformed roots. The transformation frequency was enhanced through preculturing for 2 days followed by infection for 20 min. The UV-B stress treatment of hairy roots resulted in a striking increase of rutin and quercetin production. Furthermore, the hairy root lines of TB3,TB7 and TB28 were chosen to study the specific effects of UV-B on flavonoid accumulation and flavonoid biosynthetic gene expression by qRT-PCR. This study has demonstrated that the UV-B radiation was an effective elicitor that dramatically changed in the transcript abundance of FtPAL, FtCHI, FtCHS, FtF3H and FtFLS-1 in F. tataricum hairy roots.

  13. UV B-Induced Vertical Migrations of Cyanobacteria in a Microbial Mat

    OpenAIRE

    Bebout, B. M.; Garcia-Pichel, F

    1995-01-01

    Exposure to moderate doses of UV B (0.35 to 0.79 W m(sup-2) s(sup-1) or 0.98 to 2.2 (mu)mol of photons m(sup-2) s(sup-1) at 310 nm) caused the surface layers of microbial mats from Solar Lake, Sinai, Egypt, to become visibly lighter green. Concurrent with the color change were rapid and dramatic reductions in gross photosynthesis and in the resultant high porewater oxygen concentrations in the surface layers of the mats. The depths at which both maximum gross photosynthesis and maximum oxygen...

  14. Increase of vitamin D2 by UV-B exposure during the growth phase of white button mushroom (Agaricus bisporus)

    DEFF Research Database (Denmark)

    Kristensen, Hanne; Rosenqvist, Eva S. K.; Jakobsen, Jette

    2012-01-01

    Background: Mushrooms are the only non-animal food source of vitamin D. Wild mushrooms have naturally high vitamin D2 content, and cultivated mushrooms produce vitamin D2 from ergosterol when exposed to supplementary UV-B during the post-harvest phase. Objectives: This study investigated...... the effects of providing supplementary UV-B during the growth phase on vitamin D2 formation and the interactions with growth of mushrooms, as compared to supplementary UV-B during the post-harvest phase or exposure to sunlight for both cultivated and wild mushrooms. Methods: Experiments were carried out...... with exposure to supplementary UV-B just prior to harvest in the range of 0-2,400 mJ cm-2. Mushrooms grew for 2 days with or without repeated UV-B exposure each day. Vitamin D2 and growth rate were determined. Some mushrooms were post-harvest treated by exposure at 200 mJ cm-2 supplementary UV-B or natural...

  15. Enhanced biosynthesis of quercetin occurs as A photoprotective measure in Lycopersicon esculentum mill. under Acute UV-B exposure

    Directory of Open Access Journals (Sweden)

    Abhilasha Shourie

    2014-06-01

    Full Text Available Lycopersicon esculentum respond to UV-B by enhanced synthesis of flavonoid quercetin, a strong antioxidant that helps the plants to well acclimatize to UV-B stress. Three weeks old plants of L. esculentum were subjected to acute UV-B irradiation for 20, 40 and 60 minutes daily until 28 days and analyzed for the morphological and biochemical changes. UV-B exposure for 40 and 60 minutes considerably affected the growth and biomass of L. esculentum. The leaves were deformed, developed chlorosis and abscised early as compared to the unexposed plants. Biomass declined by 35% and total chlorophyll decreased by 24.7% due to disintegration of chloroplasts. Enhancement was seen in the content of carotenoids, anthocyanins and total flavonoids by 15, 33.3 and 22.8%, respectively, which was attributed to the photoprotective role of these compounds as potential quenchers of excess excitation energy. Quercetin content decreased on UV-B exposure to 20 and 40 min, and thereafter increased significantly by 5.19% on 60 min of exposure. This pattern probably indicated that the over-expression of genes involved in its biosynthesis such as phenylalanine ammonia lyase (PAL, chalcone synthase (CHS, flavanone 3-hydroxylase (F3H and dihydroflavonol 4-reductase (DFR occurred only after certain threshold exposure (60 min, which could be the strategy for developing tolerance against UV-B stress in L. esculentum.

  16. UV-B induced transcript accumulation of DAHP synthase in suspension-cultured Catharanthus roseus cells

    Science.gov (United States)

    2010-01-01

    The enzyme 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase (EC 4.1.2.15) catalyzes the first committed step in the shikimate pathway of tryptophan synthesis, an important precursor for the production of terpenoid indole alkaloids (TIAs). A full-length cDNA encoding nuclear coded chloroplast-specific DAHP synthase transcript was isolated from a Catharanthus roseus cDNA library. This had high sequence similarity with other members of plant DAHP synthase family. This transcript accumulated in suspension cultured C. roseus cells on ultraviolet (UV-B) irradiation. Pretreatment of C.roseus cells with variety of agents such as suramin, N-acetyl cysteine, and inhibitors of calcium fluxes and protein kinases and MAP kinase prevented this effect of UV-B irriadiation. These data further show that the essential components of the signaling pathway involved in accumulation DAHP synthase transcript in C. roseus cells include suramin-sensitive cell surface receptor, staurosporine-sensitive protein kinase and MAP kinase. PMID:20704760

  17. Effect of exogenous nitric oxide on antioxidant system of Taxus chinensis var. mairei under UV-B stress%外源NO对UV-B胁迫下红豆杉抗氧化系统的影响

    Institute of Scientific and Technical Information of China (English)

    李德文; 李美兰; 于景华; 祖元刚

    2012-01-01

    为探讨一氧化氮(nitric oxide,NO)对紫外线-B( UV-B)辐射胁迫下植物抗氧化系统的影响,以盆栽5年生南方红豆杉(Taxus chinensis var.mairei)幼苗为材料,硝普钠(sodium nitroprusside,SNP)为外源NO供体,设置CK(对照)、SNP(+0.1 mmol·L-1SNP)、UV-B(+4.22 kJ·m-2·d-1 UV-B)及UV-B+ SNP(+0.1 mmol·L-1 SNP+4.22 kJ·m-2·d-1UV-B)4个处理,研究外源NO对UV-B胁迫下南方红豆杉幼苗针叶过氧化氢(H2O2)含量、脂质过氧化程度及抗氧化物质含量的影响.结果表明:UV-B胁迫显著提高了南方红豆杉针叶H2O2及MDA含量(P<0.05),施加外源NO降低UV-B胁迫下针叶H2O2及MDA含量,提高紫杉醇、类黄酮及类胡萝卜素等抗氧化物质含量(P<0.05);各处理对抗氧化酶活性影响不同,SNP处理显著提高针叶中CAT和POD活性(P<0.05),UV-B和SNP+UV-B处理均提高针叶中POD活性,降低CAT活性和APX活性(P<0.05).本研究证实,外源NO可提高UV-B胁迫下植物抗氧化酶活性和抗氧化物质含量,降低其H2O2含量及脂质过氧化程度,从而在一定程度上缓解UV-B胁迫对植物的伤害.%In order to approach the effect of nitric oxide ( NO) on the plant antioxidant system under the stress of UV-B radiation, a pot experiment with 5-year old Taxus chinensis var. mairei seedlings was conducted to study the effect of sodium nitroprusside (SNP) as an exogenous NO donor on" the seedlings leaf antioxidant system under elevated UV-B radiation. Four treatments, i. e. , CK (control) , SNP (+ 0..1 mmol · L-1 of SNP) , UV-B ( +4.22 kJ·m-2 · d-1 UV-B), and UV-B+SNP ( + 0. 1 mmol · L-1 of SNP + 4. 22 kJ · m- · d-1 UV-B) , were installed, and the leaf hydrogen peroxide ( H2 O2) , malondialdehyde ( MD A ) , and antioxidant concentrations were measured. Elevated UV-B radiation increased the leaf H2O2 and MDA concentrations significantly (P<0.05) , while exogenous NO addition decreased the H2O2 and MDA concentrations and increased the taxol, flavonoids

  18. Depicting the Dependency of Isoprene in Ambient Air and from Plants on Temperature and Solar Radiation by Using Regression Analysis

    Science.gov (United States)

    Saxena, Pallavi; Ghosh, Chirashree

    2016-07-01

    Among all sources of volatile organic compounds, isoprene emission from plants is an important part of the atmospheric hydrocarbon budget. In the present study, isoprene emission capacity at the bottom of the canopies of plant species viz. Dalbergia sissoo and Nerium oleander and in ambient air at different sites selected on the basis of land use pattern viz. near to traffic intersection with dense vegetation, away from traffic intersection with dense vegetation under floodplain area (Site I) and away from traffic intersection with dense vegetation under hilly ridge area (Site II) during three different seasons (monsoon, winter and summer) in Delhi were measured. In order to find out the dependence of isoprene emission rate on temperature and solar radiation, regression analysis has been performed. In case of dependency of isoprene in ambient air on temperature and solar radiation in selected seasons it has been found that high isoprene was found during summer season as compared to winter and monsoon seasons. Thus, positive linear relationship gives the best fit between temperature, solar rdaiation and isoprene during summer season as compared to winter and monsoon season. On the other hand, in case of isoprene emission from selected plant species, it has been found that high temperature and solar radiation promotes high isoprene emission rates during summer season as compared to winter and monsoon seasons in D. sissoo. Thus, positive linear relationship gives the best fit between temperature, solar radiation and isoprene emission rate during summer season as compared to winter and monsoon season. In contrast, in case of Nerium oleander, no such appropriate relationship was obtained. The study concludes that in ambient air, isoprene concentration was found to be high during summer season as compared to other seasons and gives best fit between temperature, solar radiation and isoprene. In case of plants, Dalbergia sissoo comes under high isoprene emission category

  19. Automatic national network of radiation environmental monitoring in Mexico; Red nacional automatica de monitoreo radiologico ambiental en Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Aguirre, Jaime; Delgado, Jose L.; Lopez, Manuel; Zertuche, Jorge V., E-mail: jaguirre@cnsns.gob.mx, E-mail: jldelgado@cnsns.gob.mx, E-mail: mlopez@cnsns.gob.mx, E-mail: jorge.zertuche@cnsns.gob.mx [Comision Nacional de Seguridad Nuclear y Salvaguardias (CNSNS), D.F. (Mexico). Direccion de Vigilancia Radiologica

    2013-07-01

    The Direccion de Vigilancia Radiologica (DVR) of the Comision Nacional de Seguridad Nuclear y Salvaguardias (CNSNS) de Mexico, performs several function for environmental radiation monitoring. One of these functions is the permanent monitoring of the environmental gamma radiation. For this, it implemented the Red Nacional Automatica de Monitoreo Radiologico Ambiental (RENAMORA) - the National Automated Network for Environmental Radiation Monitoring,which currently comprises 60 detector probes for gamma radiation which with a programmable system that includes information technologies, data transmission and software can send the information in real time to a primary center of data located in the facilities of CNSNS. - When the data are received, the system performs the verification and extraction of the information organized in Tables and charts, and generates a report of environmental gamma radiation dose rate average for each of the probes and for each period of time determined bu CNSNS. The RENAMORA covers the main cities and allows to establish the bases of almost the entire country, as well as to warn about abnormal situations caused by incidents or natural events generated by human activities inside or outside the country which involves radioactive materials; paying special attention to main radiological sites, such as the surroundings of the Laguna Verde Nuclear Power Plants, research centers and the radioactive waste disposal sites.

  20. Calibration procedures of area monitors in terms of the Ambient Dose Equivalent H*(10), for gamma, x-ray radiation fields

    International Nuclear Information System (INIS)

    In the present thesis procedures for calibrating portable survey meters in terms of the new ICRU quantities H*(10) ambient dose equivalent are discussed. Also the remendations of International Comission on Radiation Protection in their report ICRP 60 that inludes the operational magnitudes that the International Comission of Radiation Units proposed for calibrating area monitors

  1. The effect of warming and enhanced ultraviolet radiation on gender-specific emissions of volatile organic compounds from European aspen.

    Science.gov (United States)

    Maja, Mengistu M; Kasurinen, Anne; Holopainen, Toini; Julkunen-Tiitto, Riitta; Holopainen, Jarmo K

    2016-03-15

    Different environmental stress factors often occur together but their combined effects on plant secondary metabolism are seldom considered. We studied the effect of enhanced ultraviolet (UV-B) (31% increase) radiation and temperature (ambient +2 °C) singly and in combination on gender-specific emissions of volatile organic compounds (VOCs) from 2-year-old clones of European aspen (Populus tremula L.). Plants grew in 36 experimental plots (6 replicates for Control, UV-A, UV-B, T, UV-A+T and UV-B+T treatments), in an experimental field. VOCs emitted from shoots were sampled from two (1 male and 1 female) randomly selected saplings (total of 72 saplings), per plot on two sampling occasions (June and July) in 2014. There was a significant UV-B×temperature interaction effect on emission rates of different VOCs. Isoprene emission rate was increased due to warming, but warming also modified VOC responses to both UV-A and UV-B radiation. Thus, UV-A increased isoprene emissions without warming, whereas UV-B increased emissions only in combination with warming. Warming-modified UV-A and UV-B responses were also seen in monoterpenes (MTs), sesquiterpenes (SQTs) and green leaf volatiles (GLVs). MTs showed also a UV × gender interaction effect as females had higher emission rates under UV-A and UV-B than males. UV × gender and T × gender interactions caused significant differences in VOC blend as there was more variation (more GLVs and trans-β-caryophyllene) in VOCs from female saplings compared to male saplings. VOCs from the rhizosphere were also collected from each plot in two exposure seasons, but no significant treatment effects were observed. Our results suggest that simultaneous warming and elevated-UV-radiation increase the emission of VOCs from aspen. Thus the contribution of combined environmental factors on VOC emissions may have a greater impact to the photochemical reactions in the atmosphere compared to the impact of individual factors acting alone.

  2. Involvement of inositol biosynthesis and nitric oxide in the mediation of UV-B induced oxidative stress

    Directory of Open Access Journals (Sweden)

    Dmytro I Lytvyn

    2016-04-01

    Full Text Available The involvement of NO-signaling in ultraviolet B (UV-B induced oxidative stress in plants is an open question. Inositol biosynthesis contributes to numerous cellular functions, including the regulation of plants tolerance to stress. This work reveals the involvement of inositol-3-phosphate synthase 1 (IPS1, a key enzyme for biosynthesis of myo-inositol and its derivatives, in the response to NO-dependent oxidative stress in Arabidopsis. Homozygous mutants deficient for IPS1 (atips1 and wild-type plants were transformed with a reduction-oxidation-sensitive green fluorescent protein 2 (grx1-rogfp2 and used for the dynamic measurement of UV-B-induced and SNP (sodium nitroprusside-mediated oxidative stresses by confocal microscopy. atips1 mutants displayed greater tissue-specific resistance to the action of UV-B than the wild type. SNP can act both as an oxidant or repairer depending on the applied concentration, but mutant plants were more tolerant than the wild type to nitrosative effects of high concentration of SNP. Additionally, pretreatment with low concentrations of SNP (10, 100 μM before UV-B irradiation resulted in a tissue-specific protective effect that was enhanced in atips1. We conclude that the interplay between nitric oxide and inositol signaling can be involved in the mediation of UV-B-initiated oxidative stress in the plant cell.

  3. Ambient radioactivity levels and radiation doses. Annual report 2013; Umweltradioaktivitaet und Strahlenbelastung. Jahresbreicht 2013

    Energy Technology Data Exchange (ETDEWEB)

    Hachenberger, Claudia; Trugenberger-Schnabel, Angela; Loebke-Reinl, Angelika; Peter, Josef (comps.) [Bundesamt fuer Strahlenschutz, Salzgitter (Germany)

    2015-04-15

    The report on environmental radioactivity and radiation exposure 2013 includes data concerning the following issues: sources of natural and artificial radioactivity, radon in buildings, radioactive materials in construction materials and industrial products, nuclear weapon tests, the consequences of reactor accidents in Chernobyl and Fukushima, nuclear facilities, occupational exposure, radiation exposure from medical applications, handling of radioactive materials in research and technology, radioactive wastes, radiation accidents and specific incidents.

  4. The co-application effects of fullerene and ascorbic acid on UV-B irradiated mouse skin

    International Nuclear Information System (INIS)

    The role of fullerene as a pro-oxidant or anti-oxidant in Ultraviolet B ray (UV-B)-induced disorders in mouse skin was investigated. Fullerene gave no photo-toxic effect to UV-B-irradiated mouse skin. Since erythema was concentrated at the pore circumference in a UV-B irradiation experiment in mouse skin, the sebaceous gland pairs was strongly implicated as a site for the generation of reactive oxygen species (ROS). In a histological evaluation of the skin stained with CH3MDFDA (ROS index) and YO-Pro-1 (apoptosis index), the fluorescence intensity of a sebaceous gland significantly increased with UV-B irradiation. With the application of fullerene to UV-irradiated mouse skin, no toxicity was recognized in comparison with the control, and erythema, the ROS index, and the apoptosis index decrease with the application of fullerene. Ascorbyl radical (AA·) increased with the application of ascorbate (AA) to UV-B-irradiated mouse skin, and AA· decreased with the application of fullerene. The co-application of AA and fullerene, which suppressed AA· in vitro, significantly suppressed erythema, and also suppressed both the ROS index and apoptosis index in mouse skin after UV-B irradiation. In both mouse skin at 48 h after UV-B irradiation and in an attempt to reproduce this phenomenon artificially in vitro, a similar high AA· peak (AA·/H· > 4) was observed in electron spin resonance (ESR) charts. The binding of fullerene with AA impairs the Fenton reaction between AA and Fe-protein based on the observation of ascorbate-specific UV absorption and a linear equation for the calibration curve. Therefore, fullerene may impair the intercalation of AA to a heme pocket by binding with AA. These results suggest that the co-application of AA and fullerene is effective against oxidative skin damage caused by UV-B irradiation, and the development of an AA· inhibitor such as fullerene should be useful for reducing organ damage associated with Fe-protein oxidation.

  5. Ambient Air Quality Data Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Office of Air and Radiation??s (OAR) Ambient Air Quality Data (Current) contains ambient air pollution data collected by EPA, other federal agencies, as well as...

  6. Pine weevil feeding on Norway spruce bark has a stronger impact on needle VOC emissions than enhanced ultraviolet-B radiation

    Energy Technology Data Exchange (ETDEWEB)

    Blande, James D. [Department of Environmental Science, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio (Finland)], E-mail: James.Blande@uku.fi; Turunen, Katariina [Department of Environmental Science, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio (Finland)], E-mail: ksturune@hytti.uku.fi; Holopainen, Jarmo K. [Department of Environmental Science, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio (Finland)], E-mail: Jarmo.Holopainen@uku.fi

    2009-01-15

    Plants can respond physiologically to damaging ultraviolet-B radiation by altering leaf chemistry, especially UV absorbing phenolic compounds. However, the effects on terpene emissions have received little attention. We conducted two field trials in plots with supplemented UV-B radiation and assessed the influence of feeding by pine weevils, Hylobius abietis L., on volatile emissions from 3-year old Norway spruce trees (Picea abies L. Karst.). We collected emissions from branch tips distal to the feeding weevils, and from whole branches including the damage sites. Weevil feeding clearly induced the emission of monoterpenes and sesquiterpenes, particularly linalool and (E)-{beta}-farnesene, from branch tips, and the sums of monoterpenes and sesquiterpenes emitted by whole branches were substantially increased. We discovered little effect of UV-B radiation up to 30% above the ambient level on volatile emissions from branch tips distal to damage sites, but there was a possible effect on bark emissions from damage sites. - Chronic exposure to enhanced UV-B radiation has little effect on volatile emissions of Norway spruce.

  7. Photosynthesis of two Arctic macroalgae under different ambient radiation levels and their sensitivity to enhanced UV radiation

    NARCIS (Netherlands)

    Brouwer, P.E.M.; Bischof, K.; Hanelt, D.; Kromkamp, J.C.

    2000-01-01

    The change in optimal quantum efficiency (F-v/F-m) of the Arctic species Laminaria saccharina and Palmaria palmata was investigated in a long-term experiment in situ under different radiation levels during the summer of 1997 in the Kongsfjord (Ny-Alesund, Spitsbergen, Norway, 78 degrees 55.5'N, 11 d

  8. Ocean acidification mediates photosynthetic response to UV radiation and temperature increase in the diatom Phaeodactylum tricornutum

    Directory of Open Access Journals (Sweden)

    E. W. Helbling

    2012-06-01

    Full Text Available Increasing atmospheric CO2 concentration is responsible for progressive ocean acidification, ocean warming as well as decreased thickness of upper mixing layer (UML, thus exposing phytoplankton cells not only to lower pH and higher temperatures but also to higher levels of solar UV radiation. In order to evaluate the combined effects of ocean acidification, UV radiation and temperature, we used the diatom Phaeodactylum tricornutum as a model organism and examined its physiological performance after grown under two CO2 concentrations (390 and 1000 µatm for more than 20 generations. Compared to the ambient CO2 level (390 µatm, growth at the elevated CO2 concentration increased non-photochemical quenching (NPQ of cells and partially counteracted the harm to PSII caused by UV-A and UV-B. Such an effect was less pronounced under increased temperature levels. As for photosynthetic carbon fixation, the rate increased with increasing temperature from 15 to 25 °C, regardless of their growth CO2 levels. In addition, UV-induced inhibition of photosynthesis was inversely correlated to temperature. The ratio of repair to UV-induced damage showed inverse relationship with increased NPQ, showing higher values under the ocean acidification condition against UV-B, reflecting that the increased pCO2 and lowered pH counteracted UV-B induced harm.

  9. PI3P 和 NO 在 UV-B 诱导蚕豆气孔关闭中的关系%The interactions of PI3P and NO in UV-B-induced stomatal closure of broad bean

    Institute of Scientific and Technical Information of China (English)

    樊彩明; 王静; 胡洁; 贺军民

    2015-01-01

    By stomatal bioassay and measurement of endogenous nitric oxide (NO)level in guard cells,the interactions of NO and phosphatidylinositol 3-phosphate (PI3P)[the product of phos-phatidylinositol 3-kinase (PI3K)]in UV-B-induced stomatal closure were studied in the epidermal strips of abaxial surface of broad bean(Vicia faba L.)leaves.The results showed that both the NO production in guard cells and stomatal closure induced by UV-B were significantly inhibited by PI3K inhibitors wortmannin (WM)and LY294002 (LY).Meanwhile,exogenous NO-relea-sing compound sodium nitroprusside (SNP)could completely reverse the inhibitory effect of LY and WM on the UV-B-induced stomatal closure,and WM and LY could not inhibit exogenous SNP-induced stomatal closure of broad bean.These results indicate that PI3P acts upstream of NO in the signal transduction pathway of UV-B-induced stomatal closure of broad bean.%以蚕豆(Vicia faba L.)叶片下表皮为材料,结合气孔开度分析和保卫细胞内源一氧化氮(NO)水平的测定,研究了 NO 和磷脂酰肌醇3-激酶(PI3K)的催化产物磷脂酰肌醇3-磷酸(PI3P)在紫外线 B(UV-B)诱导气孔关闭中的关系。结果显示:UV-B 辐射诱导蚕豆保卫细胞 NO 产生和气孔关闭的效应能被 PI3K 抑制剂沃曼青霉素(WM)和 LY294002(LY)显著抑制。同时,外源 NO释放剂硝普钠(SNP)处理能完全逆转 WM 和 LY 对 UV-B 诱导气孔关闭的抑制效应,而 WM 和LY 却不能抑制外源 SNP 诱导蚕豆气孔关闭的效应。结果说明,在 UV-B 诱导蚕豆气孔关闭的信号转导途径中 PI3P 的作用在 NO 上游。

  10. Ambient radiation levels in a microPET/CT research laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Sarmento, D.M.; Rodrigues, D.L.; Sanches, M.P.; Carneiro, J.C.G.G., E-mail: janetegc@ipen.br [Instituto de Pesquisas Energeticas e Nucleres (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    This study focuses on initial radiological evaluation and the exposure situation related to the worker task in a micro-positron emission tomography/computed tomography laboratory (microPET/CT). Selected and calibrated thermoluminescent dosimeters, TLD, of CaSO{sub 4}:Dy were used to measure room radiation levels. The detectors were placed in several selected points inside the microPET/CT laboratory and adjacent rooms. In addition, the occupationally exposed workers were monthly evaluated for external and internal exposures. In none of the selected points the dose values exceeded the radiation dose limit established for supervised area, as well as the values obtained in individual monitoring. (author)

  11. Ambient radiation levels in a microPET/CT research laboratory

    International Nuclear Information System (INIS)

    This study focuses on initial radiological evaluation and the exposure situation related to the worker task in a micro-positron emission tomography/computed tomography laboratory (microPET/CT). Selected and calibrated thermoluminescent dosimeters, TLD, of CaSO4:Dy were used to measure room radiation levels. The detectors were placed in several selected points inside the microPET/CT laboratory and adjacent rooms. In addition, the occupationally exposed workers were monthly evaluated for external and internal exposures. In none of the selected points the dose values exceeded the radiation dose limit established for supervised area, as well as the values obtained in individual monitoring. (author)

  12. Gamma radiation levels in the ambient environment of the QNPP Base

    Institute of Scientific and Technical Information of China (English)

    WENG Jianqing; HE Jun; XIANG Yuanyi; WANG Kan; LI Xia; HAN Zhengdong

    2007-01-01

    Monitoring results of gamma dose rate level in 1992-2004 in the ambient environment of the Qinshan Nuclear Power Plants(QNPP)Base,the northeast of Zhejiang Province.are reported in this paper.It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84-113 nGy/h.with an average of 96 nGy/h in the 13 years.The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base,and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City.Within 50 km from the QNPP Base,the cumnlative dose rate of the thermoluminescent dosimeter(TLD)is 90 nGy/h,which is lower than the background level of 111 nGy/h.

  13. Analysis of limitations to CO2 assimilation on exposure of leaves of two Brassica napus cultivars to UV-B

    International Nuclear Information System (INIS)

    Apex and Bristol cultivars of oilseed rape (Brassica napus) were irradiated with 0.63 W m−2 of UV-B over 5 d. Analyses of the response of net leaf carbon assimilation to intercellular CO2 concentration were used to examine the potential limitations imposed by stomata, carboxylation velocity and capacity for regeneration of ribulose 1,5-bis-phosphate on leaf photosynthesis. Simultaneous measurements of chlorophyll fluorescence were used to estimate the maximum quantum efficiency of photosystem II (PSII) photochemistry, the quantum efficiency of linear electron transport at steady-state photosynthesis, and the light and CO2-saturated rate of linear electron transport. Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) content and activities were assayed in vitro. In both cultivars the UV-B treatment resulted in decreases in the light-saturated rate of CO2 assimilation, which were accompanied by decreases in carboxylation velocity and Rubisco content and activity. No major effects of UV-B were observed on end-product inhibition and stomatal limitation of photosynthesis or the rate of photorespiration relative to CO2 assimilation. In the Bristol cultivar, photoinhibition of PSII and loss of linear electron transport activity were observed when CO2 assimilation was severely inhibited. However, the Apex cultivar exhibited no major inhibition of PSII photochemistry or linear electron transport as the rate of CO2 assimilation decreased. It is concluded that loss of Rubisco is a primary factor in UV-B inhibition of CO2 assimilation. (author)

  14. Response of growth and antioxidant enzymes in Azolla plants (Azolla pinnata and Azolla filiculoides) exposed to UV-B.

    Science.gov (United States)

    Masood, Amjad; Zeeshan, M; Abraham, G

    2008-06-01

    Effect of ultravilolet-B (0.4 Wm(-2)) irradiation on growth, flavonoid content, lipid peroxidation, proline accumulation and activities of superoxide dismutase and peroxidase was comparatively analysed in Azolla pinnata and Azolla filiculoides. Growth measured as increment in dry weight reduced considerably due to all UV-B treatments. However, the reduction was found to be severe in A. filiculoides as compared to A. pinnata. The level of UV-absorbing compound flavonoids increased significantly in A. pinnata plants whereas only a slight increase in the flavonoid content was observed in A. filiculoides. UV-B exposure led to enhanced production of malondialdehyde (MDA) and electrolyte leakage in A. filiculoides than A. pinnata. Proline accumulation also showed a similar trend. Marked differences in the activity of antioxidant enzymes such as superoxide dismutase (SOD) and peroxidase (POD) was noticed in both the plants exposed to UV-B. Our comparative studies indicate A. pinnata to be better tolerant to UV-B as compared with A. filiculoides which appears to be sensitive. PMID:18637563

  15. Skin anti-photoaging properties of ginsenoside Rh2 epimers in UV-B-irradiated human keratinocyte cells

    Indian Academy of Sciences (India)

    Sun-Joo Oh; Sihyeong Lee; Woo-Yong Choi; Chang-Jin Lim

    2014-09-01

    Ginseng, one of the most widely used herbal medicines, has a wide range of therapeutic and pharmacological applications. Ginsenosides are the major bioactive ingredients of ginseng, which are responsible for various pharmacological activities of ginseng. Ginsenoside Rh2, known as an antitumour ginsenoside, exists as two different stereoisomeric forms, 20()-ginsenoside Rh2 [20()-Rh2] and 20()-ginsenoside Rh2 [20()-Rh2]. This work aimed to assess and compare skin anti-photoaging activities of 20()-Rh2 and 20()-Rh2 in UV-B-irradiated HaCat cells. 20()-Rh2, but not 20()-Rh2, was able to suppress UV-B-induced ROS production in HaCat cells. Both stereoisomeric forms could not modulate cellular survival and NO level in UV-B-irradiated HaCat cells. Both 20()-Rh2 and 20()-Rh2 exhibited suppressive effects on UV-B-induced MMP-2 activity and expression in HaCat cells. In brief, the two stereoisomers of ginsenoside Rh2, 20()-Rh2 and 20()-Rh2, possess skin anti-photoaging effects but possibly in different fashions.

  16. Influence of postharvest UV-B treatment and fermentation on secondary plant compounds in white cabbage leaves.

    Science.gov (United States)

    Harbaum-Piayda, Britta; Palani, Kalpana; Schwarz, Karin

    2016-04-15

    The influence of postharvest UV-B on its own and in combination with fermentation (e.g. sauerkraut production) on formation and degradation of bioactive compounds was investigated in white cabbage, processed according to traditional Chinese fermentation methods. The pattern of polyphenols was affected by postharvest UV-B: Newly formed coumaroylglycoside, feruloylglycoside, caffeoylglycoside (up to 1 mg/g dry matter; 4 days) and quercetintriglycoside (0.4-0.5 mg/gdm; 4 days) might be related to postharvest increase in enzyme activity in the biosynthesis. Decreasing contents were observed for the glucosinolates glucobrassicin and 4-methoxyglucobrassicin, but the formation of the degradation products dihydroascorbigen and dihydro-4-methoxyascorbigen, which might be related to cell shrinking as mechanical damage. Fermentation resulted in deglycosidation of hydroxycinnamic acids. Newly generated cinnamic acid from coumaric acid aglycone was detected in fermented plant material combined with UV-B (50 μg/g). Glucosinolates and dihydroascorbigens were completely degraded. This study shows exemplary UV-B as a supplemental step to improve the nutritional quality of processed plants.

  17. A novel narrow band UV-B emitting phosphor-YPO4:Sb3+,Gd3+

    Institute of Scientific and Technical Information of China (English)

    邓陶丽; 闫世润; 胡建国

    2016-01-01

    YPO4 phosphors single-doped with Sb3+ or Gd3+ and co-doped with Sb3+ and Gd3+were prepared by a solid-state reaction method. The phase purity, morphology, photoluminescence excitation and emission properties of the prepared phosphors were inves-tigated. The results showed that Sb3+ could sensitize Gd3+ in the co-doped phosphors which made the phosphors excitable by short-wave ultraviolet (UV) at a wavelength between 220 and 260 nm. Under 253.7 nm excitation, the co-doped phosphors Y1–x–yPO4: Sb3+x,Gd3+yshowed strong emission of Gd3+ at a wavelength of 312 nm whose intensity changed with the doping concentrations of Gd3+ and Sb3+. The optimized Y0.77PO4:Sb3+0.07,Gd3+0.16 phosphor showed an intensity comparable to commercial LaPO4:Ce phosphor (UVB-315), making it a potential candidate for mercury low-pressure discharge narrow-band UV-B emitting lamps.

  18. Responses of PSII photochemistry efficiency and photosynthetic pigments of Saussurea superba to short-term UV-B-supplementation%高山植物美丽风毛菊PSII光化学效率和光合色素对短期增补UV-B辐射的响应

    Institute of Scientific and Technical Information of China (English)

    师生波; 尚艳霞; 师瑞; 张波

    2012-01-01

    Aims Native alpine plants that have grown and evolved on the Qinghai-Tibetan Plateau of China for a long time have developed a strong adaptation capacity for harsh environmental factors, such as low temperature, low air pressure, strong sunlight and solar UV-B radiation. The objective of this study was to determine the response of PSII photochemistry efficiency to short-term enhanced solar UV-B intensity in alpine plants. We examined whether UV-B-absorbing compounds were sufficiently efficient to protect the photosynthetic apparatus from UV-B photo-inactivation or photo-damage and evaluated the influence of UV-B radiation on photosynthetic pigments. Methods Field experiments were conducted during the 2008 and 2009 growing seasons in alpine Kobresia hu-milis meadow near Haibei Alpine Meadow Ecosystem Research Station (37°29'-37°45' N, 101°12'-101°33' E; alt. 3 200 m) using the native alpine plant Saussurea superba. Short-term UV-B-supplementation studies were performed over 5 days using UV-B-313 fluorescence lamps, which were filtered with a cellulose diacetate film to get increased UV-B treatment and a Mylar film as a control. Pulse-modulated in-vivo chlorophyll fluorescence was used to obtain rapid information of UV-B on photosynthetic processes. The 3-min dark-adapted maximum quantum efficiency of PSII photochemistry, F(V)/F(m), and PSII photochemistry efficiency were measured under natural sunlight. The contents of photosynthetic pigments and UV-B-absorbing compounds were analyzed based on leaf area unit. Important findings Although there was no significant difference, F(v)/F(m) showed a decreasing trend after short-term exposure to enhanced UV-B radiation in all measurements throughout the growing season. The reduction of the actual photochemical quantum efficiency and photochemical quenching as well as the increase of non-photochemical quenching in UV-B supplemented treatment, when compared to the control, indicated there was a decrease in PSII

  19. Is pollen morphology of Salix polaris affected by enhanced UV-B irradiation? Results from a field experiment in High Arctic tundra

    NARCIS (Netherlands)

    D. Yeloff; P. Blokker; P. Boelen; J. Rozema

    2008-01-01

    This study tested the hypothesis that the thickness of the pollen wall will increase in response to enhanced UV-B irradiation, by examining the effect of enhanced UV-B irradiance on the pollen morphology of Salix polaris Wahlem. grown in a field experiment on the Arctic tundra of Svalbard. Measureme

  20. Synthesis of Glass Nanofibers Using Femtosecond Laser Radiation Under Ambient Condition

    Directory of Open Access Journals (Sweden)

    Venkatakrishnan K

    2009-01-01

    Full Text Available Abstract We report the unique growth of nanofibers in silica and borosilicate glass using femtosecond laser radiation at 8 MHz repetition rate and a pulse width of 214 fs in air at atmospheric pressure. The nanofibers are grown perpendicular to the substrate surface from the molten material in laser-drilled microvias where they intertwine and bundle up above the surface. The fibers are few tens of nanometers in thickness and up to several millimeters in length. Further, it is found that at some places nanoparticles are attached to the fiber surface along its length. Nanofiber growth is explained by the process of nanojets formed in the molten liquid due to pressure gradient induced from the laser pulses and subsequently drawn into fibers by the intense plasma pressure. The attachment of nanoparticles is due to the condensation of vapor in the plasma.

  1. Leaf apoplastic proteome composition in UV-B treated Arabidopsis thaliana mutants impaired in extracellular glutathione degradation

    Directory of Open Access Journals (Sweden)

    A. Masi

    2016-03-01

    We then compared the expression changes resulting from the mutation and from the UV-B treatment. Rearrangements occurring in apoplastic protein composition suggest the involvement of hydrogen peroxide, which may ultimately act as a signal. Other important changes related to hormonal effects, cell wall remodeling, and redox activities are also reported. We argue that oxidative stress conditions imposed by UV-B and by disruption of the gamma-glutamyl cycle result in similar stress-induced responses, to some degree at least. Data shown here are associated with the article from Trentin et al. (2015 [1]; protein data have been deposited to the PRIDE database (Vizcaíno et al., 2014 [2] with identifier PXD001807.

  2. UV-B and B-band Optical Flare Search in AR Lacertae, II Pegasi, and UX Arietis Star Systems

    Science.gov (United States)

    Vander Haagen, G. A.

    2013-11-01

    A high-cadence search was conducted on the known RS CVn-type flare stars AR Lac, II Peg, and UX Ari. Two optical flares were observed in the B-band on AR Lac at 5 milliseconds (ms) resolution for a rate of 0.04 fl/hr. Flare energy of the two B-band fast-flares ranged from 0.55 to 16.7 × 1033 ergs. The UV-B and B-band search of II Peg for 44.5 hours at 5 and 10 ms resolution and UV-B band search of UX Ari for 25.6 hours at 10 ms resolution detected no flare activity.

  3. In vivo activation of human immunodeficiency virus type 1 long terminal repeat by UV type A (UV-A) light plus psoralen and UV-B light in the skin of transgenic mice.

    OpenAIRE

    Morrey, John D; Bourn, S M; Bunch, T.D.; Jackson, M K; Sidwell, R. W.; Barrows, L R; Daynes, R A; Rosen, C A

    1991-01-01

    UV irradiation has been shown to activate the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) in cell culture; however, only limited studies have been described in vivo. UV light has been categorized as UV-A (400 to 315 nm), -B (315 to 280 nm), or -C (less than 280 nm); the longer wavelengths are less harmful but more penetrative. Highly penetrative UV-A radiation constitutes the vast majority of UV sunlight reaching the earth's surface but is normally harmless. UV-B ir...

  4. Vitamin D2 Formation from Post-Harvest UV-B Treatment of Mushrooms (Agaricus bisporus) and Retention during Storage

    Science.gov (United States)

    The objectives of this research were to study the effects of high intensity (0.5, 0.75, and 1.0 mW/cm2), dose (0.5, 1.0, and 1.5 J/cm2), and post-harvest time (1 and 4 days) on the vitamin D2 formation in Portabella mushrooms (Agaricus bisporus) as a result of UV-B exposure, as well as the vitamin D...

  5. The interplay of transcription factors in suppression of UV-B induced flavonol accumulation by flg22

    OpenAIRE

    Schenke, Dirk; Cai, Daguang

    2014-01-01

    Biotic stress can be mimicked by application of elicitors, which comprise of microbe-associated molecular patterns (MAMPs). Treatment of plant cell cultures with MAMPs such as flg22 suppressed the expression of UV-B-induced flavonol pathway genes (FPGs) in parsley, carrot and Arabidopsis. This is thought to allow the plant focusing its secondary metabolism on the pathogen defense during MAMP-triggered immunity (MTI). Recently we reported that this suppression also depends on prevention of his...

  6. UV-B-induced signaling events leading to enhanced-production of catharanthine in Catharanthus roseus cell suspension cultures

    Science.gov (United States)

    Ramani, Shilpa; Chelliah, Jayabaskaran

    2007-01-01

    Background Elicitations are considered to be an important strategy towards improved in vitro production of secondary metabolites. In cell cultures, biotic and abiotic elicitors have effectively stimulated the production of plant secondary metabolites. However, molecular basis of elicitor-signaling cascades leading to increased production of secondary metabolites of plant cell is largely unknown. Exposure of Catharanthus roseus cell suspension culture to low dose of UV-B irradiation was found to increase the amount of catharanthine and transcription of genes encoding tryptophan decarboxylase (Tdc) and strictosidine synthase (Str). In the present study, the signaling pathway mediating UV-B-induced catharanthine accumulation in C. roseus suspension cultures were investigated. Results Here, we investigate whether cell surface receptors, medium alkalinization, Ca2+ influx, H2O2, CDPK and MAPK play required roles in UV-B signaling leading to enhanced production of catharanthine in C. roseus cell suspension cultures. C. roseus cells were pretreated with various agonists and inhibitors of known signaling components and their effects on the accumulation of Tdc and Str transcripts as well as amount of catharanthine production were investigated by various molecular biology techniques. It has been found that the catharanthine accumulation and transcription of Tdc and Str were inhibited by 3–4 fold upon pretreatment of various inhibitors like suramin, N-acetyl cysteine, inhibitors of calcium fluxes, staurosporine etc. Conclusion Our results demonstrate that cell surface receptor(s), Ca2+ influx, medium alkalinization, CDPK, H2O2 and MAPK play significant roles in UV-B signaling leading to stimulation of Tdc and Str genes and the accumulation of catharanthine in C. roseus cell suspension cultures. Based on these findings, a model for signal transduction cascade has been proposed. PMID:17988378

  7. UV-B-induced signaling events leading to enhanced-production of catharanthine in Catharanthus roseus cell suspension cultures

    Directory of Open Access Journals (Sweden)

    Chelliah Jayabaskaran

    2007-11-01

    Full Text Available Abstract Background Elicitations are considered to be an important strategy towards improved in vitro production of secondary metabolites. In cell cultures, biotic and abiotic elicitors have effectively stimulated the production of plant secondary metabolites. However, molecular basis of elicitor-signaling cascades leading to increased production of secondary metabolites of plant cell is largely unknown. Exposure of Catharanthus roseus cell suspension culture to low dose of UV-B irradiation was found to increase the amount of catharanthine and transcription of genes encoding tryptophan decarboxylase (Tdc and strictosidine synthase (Str. In the present study, the signaling pathway mediating UV-B-induced catharanthine accumulation in C. roseus suspension cultures were investigated. Results Here, we investigate whether cell surface receptors, medium alkalinization, Ca2+ influx, H2O2, CDPK and MAPK play required roles in UV-B signaling leading to enhanced production of catharanthine in C. roseus cell suspension cultures. C. roseus cells were pretreated with various agonists and inhibitors of known signaling components and their effects on the accumulation of Tdc and Str transcripts as well as amount of catharanthine production were investigated by various molecular biology techniques. It has been found that the catharanthine accumulation and transcription of Tdc and Str were inhibited by 3–4 fold upon pretreatment of various inhibitors like suramin, N-acetyl cysteine, inhibitors of calcium fluxes, staurosporine etc. Conclusion Our results demonstrate that cell surface receptor(s, Ca2+ influx, medium alkalinization, CDPK, H2O2 and MAPK play significant roles in UV-B signaling leading to stimulation of Tdc and Str genes and the accumulation of catharanthine in C. roseus cell suspension cultures. Based on these findings, a model for signal transduction cascade has been proposed.

  8. Effect of UV-B irradiance on the ATP content of microorganisms of the Weddell Sea (Antartica)

    Energy Technology Data Exchange (ETDEWEB)

    Vosjan, J.H.; Nieuwland, G. (Netherlands Inst. for Sea Research, Den Burg (Netherlands)); Doehler, G. (Frankfurt Universitaet (Federal Republic of Germany). Botanisches Institut)

    1990-06-01

    The effect of UV-B irradiation on the ATP content of natural assemblages of planktonic microorganisms in the upper 30-m water layer of the Weddell Sea (Antartica) was studied. After five hours of irradiation with UV (290-320 nm) of 1.35 W.m{sup -2} a 75% decrease in the ATP content of the microorganisms was observed. (author). 11 refs.; 3 figs.

  9. Ultraviolet-b radiation effects on water relations, leaf development, and photosynthesis in droughted pea plants

    International Nuclear Information System (INIS)

    The effects of ultraviolet-B (UV-B) radiation on water relations leaf development and gas-exchange characteristics in pea (Pisum sativum L. cv Meteor) plants subjected to drought were investigated. Plants grown throughout their development under a high irradiance of UV-B radiation (0.63 W m-2) were compared with those grown without UV-B radiation and after 12 d one-half of the plants were subjected to 24 d of drought that resulted in mild water stress. UV-B radiation resulted in a decrease of adaxial stomatal conductance by approximately 65%, increasing stomatal limitation of CO2 uptake by 10 to 15%. However, there was no loss of mesophyll light saturated photosynthetic activity. Growth in UV-B radiation resulted in large reductions of leaf area and plant biomass which were associated with a decline in leaf cell numbers and cell division UV-B radiation also inhibited epidermal cell expansion of the exposed surface of leaves. There was an interaction between UV-B radiation and drought treatments: UV-B radiation both delayed and reduced the severity of drought stress through reductions in plant water-loss rates, stomatal conductance, and leaf area

  10. Short-term UV-B exposure induces metabolic and anatomical changes in peel of harvested lemons contributing in fruit protection against green mold.

    Science.gov (United States)

    Ruiz, V E; Interdonato, R; Cerioni, L; Albornoz, P; Ramallo, J; Prado, F E; Hilal, M; Rapisarda, V A

    2016-06-01

    UV-B radiation (UVBR) is a small fraction of the solar spectrum from 280 to 315nm. UVBR produces photomorphogenic acclimation responses in plants, modulating their cellular structure and physiology. Here, changes in the peel of harvested lemons after short time exposure to UVBR were analyzed and its potential effects against fungal infection were studied. In the flavedo, UVBR treatment induced variations in the respiratory profiles and increased the phenolic compound contents. Final products of the flavonoid pathway (flavones, flavonols and anthocyanins) increased more markedly than their precursors (flavanones and dihydroflavonols). The increased accumulation of soluble phenolics in the flavedo of treated lemons is associated with the high antioxidant activity found in the flavedo of these samples. Supporting the biochemical determinations, anatomical observations showed abundant intravacuolar deposits of phenolic compounds and an increase in the cell wall thickness in UVBR-treated samples. Metabolic and anatomical modifications associated to UVBR improved natural defenses against Penicillium digitatum, the causal agent of green mold disease. Our results suggest that mature postharvest lemons exposed to the artificial radiation showed phenotypic plasticity, allowing an acclimation response to UVBR which confers fruit resistance to pathogens. Thus, combination of UVBR with other treatments could represent an important improvement to control postharvest diseases on citrus. PMID:27017432

  11. Medición y predicción de la radiación solar global UV-B bajo cielos claros y sin nubes

    Directory of Open Access Journals (Sweden)

    Jaime Wright Gilmore

    2016-03-01

    Full Text Available Se presentan mediciones experimentales de la radiación solar ultravioleta en el rango B del espectro solar (UV-B y la radiación ultravioleta en el rango total RUV (UV-A+UV-B en días claros y sin nubes en Heredia, Costa Rica. Se utilizó una radiómetro UV-B, que mide la radiación solar en el rango espectral 280-315 nm, y un radiómetro RUV, que mide la radiación solar en el rango espectral 280-385 nm. La dependencia entre entre UV-B y RUV también fue investigada, y se encontró un excelente grado de asociación entre ambas. Además se detalló que UV-B representa solamente un 5,4% de RUV, a pesar de que UV-B es mil veces más potente que UV-A. Los valores de UV-B medidos in situ fueron comparados con los valores predichos por un modelo atmosférico espectral, el cual utiliza como datos de entrada: la hora del día, la latitud, la altitud, el albedo superficial, la distancia Tierra-Sol, la turbiedad atmosférica y el ozono atmosférico. La comparación entre los valores medidos y predichos dio resultados satisfactorios.

  12. Ambient Air Quality Data Inventory

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Office of Air and Radiation's (OAR) Ambient Air Quality Data (Current) contains ambient air pollution data collected by EPA, other federal agencies, as well as...

  13. Effects of stratocumulus, cumulus, and cirrus clouds on the UV-B diffuse to global ratio: Experimental and modeling results

    International Nuclear Information System (INIS)

    Broadband measurements of global and diffuse UV-B irradiance (280-315 nm) together with modeled and measured diffuse to global ratios (DGR) have been used to characterize the influence of different types of clouds on irradiance at the surface. Measurements were carried out during 2000-2001 in Córdoba City, Argentina. The Tropospheric Ultraviolet Visible (TUV) model was used to analyze the behavior of the modeled DGRs for different cloud optical depths and at different altitudes and solar zenith angles (SZA). Different cloud altitudes were also tested, although only the results for a cloud placed at 1.5-2.5 km of altitude are shown. A total of 16 day with stratocumulus, 12 with cumulus, and 16 with cirrus have been studied and compared among them and also against 21 clear sky days. Different behaviors were clearly detected and also differentiated through the analysis of the averages and the standard deviations of the DGRs: 1.02±0.06 for stratocumulus, 0.74±0.18 for cumulus, 0.63±0.12 for cirrus, and 0.60±0.13 for the clear sky days, respectively. Stratocumulus clouds showed a low variability in the DGR values, which were concentrated close to one at all SZAs. DGR values for cumulus clouds presented a large variability at all SZAs, mostly associated with the different optical depths. Finally, the closeness between the DGR values for cirrus clouds and the DGR values for clear days showed that these clouds generally do not strongly affect the UV-B irradiance at the surface at any SZA. In the opposite side, stratocumulus clouds were identified as those with the largest effects, at all SZAs, on the UV-B irradiance at the surface.

  14. UV-B-induced differential transcription of psbA genes encoding the D1 protein of photosystem II in the cyanobacterium Synechocystis 6803

    International Nuclear Information System (INIS)

    UV-B irradiation of intact Synechocystis sp. PCC 6803 cells results in the loss of photosystem II activity, which can be repaired via de novo synthesis of the D1 (and D2) reaction center subunits. In this study, we investigated the effect of UV-B irradiation on the transcription of the psbA2 and psbA3 genes encoding identical D1 proteins. We show that UV-B irradiation increases the level of psbA2 mRNA 2-3-fold and, more dramatically, it induces a 20-30-fold increase in the accumulation of the psbA3 mRNA even at levels of irradiation too low to produce losses of either photosystem II activity or D1 protein. The induction of psbA3 transcript accumulation is specific for UV-B light (290-330 nm). Low intensity UV-A emission (330-390 nm) and white light induce only a small, at most, 2-3-fold enhancement, whereas no effect of blue light was observed. Expression patterns of chimeric genes containing the promoter regions of the psbA2, psbA3 genes fused to the firefly luciferase (luc) reporter gene indicate that (i) transcription of psbA2/luc and psbA3/luc transgenes was elevated, similarly to that of the endogenous psbA genes, by UV-B irradiation, and that (ii) a short, 80-base pair psbA3 promoter fragment is sufficient to maintain UV-B-induced transcription of the luc reporter gene. Furthermore, our findings indicate that UV-B-induced expression of the psbA2 and psbA3 genes is a defense response against UV-B stress, which is regulated, at least, partially at the level of transcription and does not require active electron transport

  15. Development of an innovative peat lipstick based on the UV-B protective effect of humic substances

    OpenAIRE

    R. Klöcking; Y. Felber; M. Guhr; Meyer, G.; Schubert, R.; J.I. Schoenherr

    2013-01-01

    Humic acids (HA) are known for their antiviral and UV-B protecting effects, and are considered promising as ingredients for a UV-protective lipstick which is being developed to minimise or even prevent recurrences of UV- induced herpes. In this study, the UV/Vis spectra of three natural HA and three synthetic HA-like substances are analysed to determine the appropriateness of their UV-absorbing characteristics for the product under development. The contribution of a matrix component (castor o...

  16. Future projections of surface UV-B in a changing climate

    Science.gov (United States)

    Watanabe, S.; Sudo, K.; Nagashima, T.; Takemura, T.; Kawase, H.; Nozawa, T.

    2011-08-01

    Results of comprehensive long-term simulations of surface all-sky and clear-sky ultraviolet (UV) radiation through 1960-2100 are presented. A new earth system model, MIROC-ESM-CHEM, is used for the simulation, which considers key processes that change the surface UV radiation: atmospheric dynamics and chemistry affecting ozone in the stratosphere and troposphere, aerosols and clouds in the troposphere, and changes in surface albedo with sea ice and snow cover. In contrast to previous assessments considering only the effect of long-term change in stratospheric ozone, the simulated long-term behavior of UV radiation in this study is strongly affected by other processes. In one of two simulations, all-sky UV radiation in the northern midlatitudes is projected to increase in the 21st century despite the expected recovery of the stratospheric ozone layer. Reductions in aerosols and clouds are expected to overcompensate for the effect of ozone recovery. The results are sensitive to the future socioeconomic scenario, describing GHG concentrations and emissions of aerosol and ozone precursors in the troposphere. The interannual variability of UV radiation associated with the 11 year solar cycle and local processes is also discussed.

  17. Effect of Rare Earths on Plants under Supplementary Ultraviolet-B Radiation: Ⅱ. Effect of Cerium on Antioxidant Defense System in Rape Seedlings under Supplementary Ultraviolet-B Radiation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Effects of cerium (Ce3 + ) on membranous protective enzymes in rape seedlings exposed to two levels of enhanced ultraviolet-B radiation (UV-B, 280 ~ 320 nm) were studied by hydroponics in the laboratory. The results show that the chlorophyll content decreases and membrane permeability increases in the leaves under UV-B irradiation with an intenposed to a low level of UV-B radiation. POD activity in leaves exposed to a high level of UV-B radiation is enhanced constantly. The sensitivities of these enzymes to UV-B radiation are SOD > CAT > POD. The injury by UV-B radiation on the functions of protective enzymes is lightened, their ability to scavenge radicals is improved, and the membrane permeability is maintained by Ce. Furthermore, the protective effect of cerium is more obvious in plants exposed to low levels of UV-B radiation than to high levels of it. Accordingly, all results prove that the protective effect of Ce on plants under UV-B radiation is realized through the protective system of plants.

  18. Assessment of ambient dose equivalent rate performance of an automatic survey meter as an instrument to quantify the presence of radiation in soils

    CERN Document Server

    Yoshimura, E M; Okuno, E

    2002-01-01

    Those who work in radiation protection are faced with various quantities that were created to account for the effects of ionizing radiation in the human body. As far as the experimental point of view is concerned, each available equipment is planned to measure a distinct quantity, for a specific radiation protection application, and it is not always clear which one it is. This paper shows a series of tests, planned and applied to a portable gamma ray spectrometer, in order to assure that the monitoring low dose levels of radiation with it is reliable. The equipment is fully automated and does not allow modifications of the conversion factors from counts to ambient dose equivalent. It is therefore necessary to assure that the values provided by the equipment are correct and refer to the actual situation one expects to find in practice. The system is based on an NaI(Tl) scintillation detector, mounted with its electronics in a portable case, suitable for field measurements. It measures ambient dose equivalent r...

  19. Effect of cerium on photosynthetic characteristics of soybean seedling exposed to supplementary ultraviolet-B radiation

    Institute of Scientific and Technical Information of China (English)

    LIANG Chan-juan; HUANG Xiao-hua; ZHOU Qing

    2006-01-01

    Effects of cerium (Ce3+) on photosynthetic characteristics were investigated by hydroponics under laboratory conditions when soybean seedlings were exposed to two levels of supplementary UV-B radiation. UV-B radiation badly inhibited the photosynthesis in soybean seedling, leading to a reduction in net photosynthetic rate (Ph), Hill reaction activity, light saturated photosynthetic rate (Ps) and apparent quanta yield (AQY), as well as the CO2 and light saturated photosynthetic rate (Pm) and carboxulation efficiency (CE). On the contrary, Ce obviously promoted the photosynthesis of plants by increasing Hill reaction activity, accelerating electron transport and photophosphorylation, and enhancing carboxylation efficiency. For Ce+UV-B treatments,the values of photosynthetic parameters were still lower than those of the control, but obviously higher than those of UV-B treatment.The results indicated that Ce alleviated the inhibition of UV-B radiation on the photosynthesis in soybean seedling to a certain extent.In correlating of Pn with Hill activity, AQY and CE, we found that the changes of photosynthetic rate were mainly influenced by the regulating effect of Ce on Hill activity and AQY at low level (0.15 W/m2) of UV-B radiation, but were dominated by the regulating effect of Ce on CE at high level (0.45 W/m2). Thus, Ce could regulate many aspects in photosynthesis of soybean seedling under UV-B stress. The regulating mechanism was close related with the dosage of UV-B radiation.

  20. Simulation of ozone depletion using ambient irradiance supplemented with UV lamps.

    Science.gov (United States)

    Díaz, S; Camilión, C; Escobar, J; Deferrari, G; Roy, S; Lacoste, K; Demers, S; Belzile, C; Ferreyra, G; Gianesella, S; Gosselin, M; Nozais, C; Pelletier, E; Schloss, I; Vernet, M

    2006-01-01

    In studies of the biological effects of UV radiation, ozone depletion can be mimicked by performing the study under ambient conditions and adding radiation with UV-B lamps. We evaluated this methodology at three different locations along a latitudinal gradient: Rimouski (Canada), Ubatuba (Brazil) and Ushuaia (Argentina). Experiments of the effect of potential ozone depletion on marine ecosystems were carried out in large outdoor enclosures (mesocosms). In all locations we simulated irradiances corresponding to 60% ozone depletion, which may produce a 130-1900% increase in 305 nm irradiance at noon, depending on site and season. Supplementation with a fixed percentage of ambient irradiance provides a better simulation of irradiance increase due to ozone depletion than supplementation with a fixed irradiance value, particularly near sunrise and sunset or under cloudy skies. Calculations performed for Ushuaia showed that, on very cloudy days, supplementation by the square-wave method may produce unrealistic irradiances. Differences between the spectra of the calculated supplementing irradiance and the lamp for a given site and date will be a function of the time of day and may become more or less pronounced according to the biological weighting function of the effect under study. PMID:17205620

  1. Ultraviolet-B radiation causes shade-type ultrastructural changes in Brassica napus

    International Nuclear Information System (INIS)

    Cell and chloroplast structural changes in palisade cells from mature leaves of Brassica napus L. cv. Paroll were quantified following exposure of plants to enhanced ultraviolet-B (280–320 nm; 13 kJ m−2 day−1 biologically effective UV-B) radiation at two different levels of photosynthetically active radiation (PAR, 400–700 nm; 200 and 700 μmol m−2 s−1). Short-term changes in leaf ultrastructure after 30 min and longer term changes after one day and one week were analyzed using stereological techniques incorporating light and electron microscopy and mathematical reconstruction of a mean cell for each sample. Ultraviolet-B together with either relatively high or low PAR resulted in cell structural changes resembling those typical of plants under shade conditions, with the most marked response occurring after 30 min of UV-B radiation. The ultrastructural changes at the cellular level were generally similar in both the relatively high and low PAR plus UV-B radiation treatments. The surface areas of all three thylakoid types, the appressed, non-appressed and margin thylakoids increased in the palisade tissue under supplemental UV-B irradiation. Although the appressed and non-appressed thylakoids increased in surface area, they did not increase equally, leaving open the possibility that the two thylakoid types have independent regulatory systems or different sensitivity to UV-B radiation. Increased thylakoid packing (mm2 thylakoid membrane per mm2 leaf surface) in UV-B-exposed plants may increase the statistical probability of photon interception. An increased level of UV-absorbing pigments after one week of supplemental UV-B radiation did not prevent or significantly ameliorate UV effects. Our data supported the assumption that UV-B radiation may have a regulatory role besides damaging effects and that an increased UV-B environment will likely increase this regulatory influence of UV-B radiation. (author)

  2. Effect of Lanthanum on Plants under Supplementary Ultraviolet-B Radiation: Effect of Lanthanum on Flavonoid Contents in Soybean Seedlings Exposed to Supplementary Ultraviolet-B Radiation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The effect of La on flavonoids, chlorophyll contents, and phenylalanine ammonia-lyase (PAL) activity in soybean seedlings under supplementary ultraviolet-B radiation (UV-B, 280 ~ 320 nm) was studied. The results show that PAL activity, contents of flavonoids and chlorophyll in the plants pretreated with La (20 mg· L-1) are higher than those in CK. UV-B radiation could result in an increase in flavonoid content and PAL activity, associated with a decrease in chlorophyll content. However, the increase in the range of PAL activity and flavonoid content in UV-B treatment are lesser than those in the La treatment. The changes of flavonoid contents and PAL activity in La + UV-B treatment are similar to those in UV-B treatment, and the increase in their range is higher than those in UV-B treatment. This shows that La can enhance the resistance of soybean seedling to UV-B radiation and alleviate the damage of UV-B radiation by increasing flavonoid content, chlorophyll content, and PAL activity.

  3. Secondary metabolites and phenylpropanoid pathway enzymes as influenced under supplemental ultraviolet-B radiation in Withania somnifera Dunal, an indigenous medicinal plant.

    Science.gov (United States)

    Takshak, Swabha; Agrawal, S B

    2014-11-01

    The present study aims to investigate the effects of supplemental ultraviolet B (3.6 kJ m(-2)day(-1) above ambient) radiation on secondary metabolites and phenylpropanoid pathway enzymes of Withania somnifera under field conditions at 40, 70, and 100 days after transplantation. Secondary metabolites' (alkaloids, anthocyanins, carotenoids, flavonoids, lignin, phytosterols, saponins, and tannins) concentrations were analysed at the end of the treatments. Activities of phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD), 4-coumarate-CoA ligase (4CL), chalcone-flavanone isomerase (CHI), and dihydroflavonol reductase (DFR) were also determined. In treated plants, secondary metabolite-concentrations generally increased (higher concentrations being recorded in roots compared to leaves). Anomalies were recorded for lycopene in roots and phytosterols in leaves (all sampling ages); β-carotene declined in leaves at third sampling age. s-UV-B-treated plants depicted decrease in withanolide A content with concomitant increase in withaferin A (two major alkaloids analysed by HPLC) compared to their respective controls. Phenylpropanoid pathway enzyme-activities increased in leaves and roots under s-UV-B treatment, the latter showing greater increase. The study concludes that s-UV-B is a potent factor in increasing the concentrations of secondary metabolites and their biosynthetic pathway enzymes in W. somnifera.

  4. UV-B对不同烤烟品种质体色素的影响%Effects of UV-B on the Plastid Pigment Content of the Different Flue-cured Tobacco Cultivars

    Institute of Scientific and Technical Information of China (English)

    马俊红; 李军营; 马二登; 李大肥; 卢秀萍

    2013-01-01

    [ Objective ] The aim was to study the effects of UV-B on the plastid pigment content of the different flue - cured tobacco cultivars, and discuss the influencing mechanism to quality of flue - cured tobacco. [ Method] Three varieties of Honghuadajinyuan, K326 and Yunyan 87 were radiated on 5 different UV-B radiation intensities. The fresh leaves of tobacco were collected after 7, 14, 21 and 28 days of treatment to detect chlorophyll and carotenoid content. [ Result] The results show that effects of the ultraviolet on plastid pigment content of different flue - cured tobacco varieties depend on UV-B intensity and irradiation time. And the differences among different varieties were very large. 30% less ultraviolet radiation treatment for 28 days leads to the plastid pigment content of middle leaf of K326 and Yunyan 87 increasing, and no change for Honghuadajinyuan. For more 1.5 h UV-B irradiation of treatment, plastid pigment content of all 3 varieties reduces after 28 days. And for more 3.0 h ultraviolet irradiation of treatment for 7 days, plastid pigment content of Honghuadajinyuan and K326 increased, chlorophyll content of Yunyan 87 decreased, carotenoid content increased. [Conclusion] This study provides important theory basis for the effects of UV-B on plastid pigment of different flue - cured tobacco varieties, improving the quality of tobacco and rational deploy of tobacco varieties.%[目的]研究不同UV-B强度对烤烟质体色素含量的影响,探讨UV-B对烤烟品质的影响机理.[方法]采用5个不同的UV-B辐射强度,对3个品种红花大金元、K326和云烟87,旺长期烟株进行辐射处理,分别采集处理7、14、21和28 d后的新鲜叶片测定叶绿素和类胡萝卜紊含量.[结果] UV-B对不同烤烟品种质体色素含量的影响随UV-B强度和照射时间而变化,且不同品种之间的差异较大.减弱30% UV-B处理28 d后,导致K326和云烟87中部叶质体色素含量升高,但对红花大金元

  5. Development of a map of environmental radiation in Aragon; Elaboracion de un mapa de radiacion ambiental en Aragon

    Energy Technology Data Exchange (ETDEWEB)

    Calvete, H. I.; Carrion, J. A.; Gale, C.; Garcia, B.; Nunez-Lagos, R.; Perez, C.; Puimedon, J.; Rodriguez, S.; Sanchez, P.; Sarsa, M. L.; Villar, J. A.; Virto, A.

    2013-06-01

    This paper presents the results of the measurements of the environmental radioactivity levels obtained in selected locations of the 33 administrative divisions of the Autonomous Region of Aragon (Spain). The ambient dose levels have been recorded by using thermoluminescent dosimeters (TLD) during a period of four years (2008-2012). the average ambient dose equivalent H (10) level in Aragon is 0.82 mSv/year. This research has been supported by the Aragon Government and the Obra Social de la Caixa under the grants GA-LC-014/2008 and GA-LC-035/2010. (Author) 6 refs.

  6. The DNA-mismatch repair enzyme hMSH2 modulates UV-B-induced cell cycle arrest and apoptosis in melanoma cells.

    Science.gov (United States)

    Seifert, Markus; Scherer, Stefan J; Edelmann, Wilfried; Böhm, Markus; Meineke, Viktor; Löbrich, Markus; Tilgen, Wolfgang; Reichrath, Jörg

    2008-01-01

    The mechanisms by which the post-replicative DNA mismatch repair (MMR) enzyme MSH2 is involved in the complex response mechanisms to UV damage are yet to be clarified. Here, we show increased levels of MSH2 mRNA in malignant melanoma, metastases of melanoma, and melanoma cell (MeWo) lines as compared with melanocytic nevi or primary cultured benign melanocytes. UV-B treatment modulated MSH2 expression and silencing of MSH2 gene expression using small interfering RNA technology regulated UV-B-induced cell cycle arrest and apoptosis in human MeWo. We show that MSH2-deficient non-malignant mouse fibroblasts (MEF-/-) are partially resistant against UV-B-induced apoptosis and show reduced S-Phase accumulation. In addition, we show that an Msh2 point mutation (MEFGA) that affects MMR does not affect UV-B-induced apoptosis. In conclusion, we demonstrate that MSH2 modulates in human melanocytes both UV-B-induced cell cycle regulation and apoptosis, most likely via independent, uncoupled mechanisms.

  7. Study of the environmental radiation in Zacatecas City; Estudio de la radiacion ambiental en la Ciudad de Zacatecas

    Energy Technology Data Exchange (ETDEWEB)

    Quirino, L.L.; Mireles, F.; Davila, J.I.; Rios, C.; Lugo, J.F.; Pinedo, J.L.; Lopez, H.; Garcia, M.L.; Soriano, J.M. [Centro Regional de Estudios Nucleares, Universidad Autonoma de Zacatecas, Cipres 10, Fracc. La Penuela, 96068 Zacatecas (Mexico)

    2000-07-01

    A study of detection of environmental radiation in the inner of an office is presented and a comparison of the results is made when the facilities are closed or aired. The used method is based on radiation detection by means of Geiger-Mueller RM 60 and RM 70 detectors with the aid of a personal computer which provides a detection method of radiation in real time. The used method in this study is suggested to detect the variation of radiation in closed or aired environments and as a surveillance system of radiation levels. The obtained results are discussed and they are compared with those obtained in another places. (Author)

  8. Moderate salt treatment alleviates ultraviolet-B radiation caused impairment in poplar plants

    Science.gov (United States)

    Ma, Xuan; Ou, Yong-Bin; Gao, Yong-Feng; Lutts, Stanley; Li, Tao-Tao; Wang, Yang; Chen, Yong-Fu; Sun, Yu-Fang; Yao, Yin-An

    2016-01-01

    The effects of moderate salinity on the responses of woody plants to UV-B radiation were investigated using two Populus species (Populus alba and Populus russkii). Under UV-B radiation, moderate salinity reduced the oxidation pressure in both species, as indicated by lower levels of cellular H2O2 and membrane peroxidation, and weakened the inhibition of photochemical efficiency expressed by O-J-I-P changes. UV-B-induced DNA lesions in chloroplast and nucleus were alleviated by salinity, which could be explained by the higher expression levels of DNA repair system genes under UV-B&salt condition, such as the PHR, DDB2, and MutSα genes. The salt-induced increase in organic osmolytes proline and glycine betaine, afforded more efficient protection against UV-B radiation. Therefore moderate salinity induced cross-tolerance to UV-B stress in poplar plants. It is thus suggested that woody plants growing in moderate salted condition would be less affected by enhanced UV-B radiation than plants growing in the absence of salt. Our results also showed that UV-B signal genes in poplar plants PaCOP1, PaSTO and PaSTH2 were quickly responding to UV-B radiation, but not to salt. The transcripts of PaHY5 and its downstream pathway genes (PaCHS1, PaCHS4, PaFLS1 and PaFLS2) were differently up-regulated by these treatments, but the flavonoid compounds were not involved in the cross-tolerance since their concentration increased to the same extent in both UV-B and combined stresses. PMID:27597726

  9. Perfiles epigenéticos en la respuesta a estrés UV-B en Pinus radiata D. Don

    OpenAIRE

    Annacondia López, María Luz

    2015-01-01

    Como consecuencia de la actual disminución de la capa de ozono, la superficie terrestre está recibiendo cantidades crecientes de UV-B (280-320 nm), las cuales causan daños considerables en las plantas. A pesar de tener una clara importancia, el estudio de la exposición a UV-B en plantas es escaso, especialmente en el caso de las especies forestales, las cuales presentan una gran implicación tanto ecológica como económica. Según estudios previos, los mecanismos epigenéticos, como las modificac...

  10. Degradation and de novo synthesis of D1 protein and psbA transcript in reinhardtii during UV-B inactivation of photosynthesis

    Indian Academy of Sciences (India)

    Ratnesh Haturvedi; Adhey Hyam

    2000-03-01

    UV-B induces intensity and time dependent inhibition of photosynthetic O evolution and PS II electron transport Chlamydomonas reinhardtii chloroplast membranes are rapidly and essential for the repair of damaged PS II as chloramphenicol accelerated UV-B inactivation of photosynthesis and psb for the D1 protein. Cells showing 72% inhibition of PS II protein. This shows that synthesis of D1 protein is not the only component involved in the recovery process. Our events, which in turn may limit the repair of damaged PS II.

  11. Interactive effects of UV radiation and reduced precipitation on the seasonal leaf phenolic content/composition and the antioxidant activity of naturally growing Arbutus unedo plants.

    Science.gov (United States)

    Nenadis, Nikolaos; Llorens, Laura; Koufogianni, Agathi; Díaz, Laura; Font, Joan; Gonzalez, Josep Abel; Verdaguer, Dolors

    2015-12-01

    The effects of UV radiation and rainfall reduction on the seasonal leaf phenolic content/composition and antioxidant activity of the Mediterranean shrub Arbutus unedo were studied. Naturally growing plants of A. unedo were submitted to 97% UV-B reduction (UVA), 95% UV-A+UV-B reduction (UV0) or near-ambient UV levels (UVBA) under two precipitation regimes (natural rainfall or 10-30% rainfall reduction). Total phenol, flavonol and flavanol contents, levels of eight phenols and antioxidant activity [DPPH(●) radical scavenging and Cu (II) reducing capacity] were measured in sun-exposed leaves at the end of four consecutive seasons. Results showed a significant seasonal variation in the leaf content of phenols of A. unedo, with the lowest values found in spring and the highest in autumn and/or winter. Leaf ontogenetic development and/or a possible effect of low temperatures in autumn/winter may account for such findings. Regardless of the watering regime and the sampling date, plant exposure to UV-B radiation decreased the total flavanol content of leaves, while it increased the leaf content in quercitrin (the most abundant quercetin derivative identified). By contrast, UV-A radiation increased the leaf content of theogallin, a gallic acid derivative. Other phenolic compounds (two quercetin derivatives, one of them being avicularin, and one kaempferol derivative, juglanin), as well as the antioxidant activity of the leaves, showed different responses to UV radiation depending on the precipitation regime. Surprisingly, reduced rainfall significantly decreased the total amount of quantified quercetin derivatives as well as the DPPH scavenging activity in A. unedo leaves. To conclude, present findings indicate that leaves of A. unedo can be a good source of antioxidants throughout the year, but especially in autumn and winter.

  12. Combined effects of enhanced ultraviolet-B radiation and doubled CO2 concentration on growth,fruit quality and yield of tomato in winter plastic greenhouse

    Institute of Scientific and Technical Information of China (English)

    LI Fangmin; WANG Jun; CHEN Yuping; ZOU Zhirong; WANG Xunling; YUE Ming

    2007-01-01

    Five different doses of ultraviolet-B (UV-B)radiation were supplied to tomato (Lycopersicon esculeutum.in the winter plastic greenhouse.The influences on the seedling growth,fruit quality and yield of tomato were investigated.Results showed that the seedling growth,and the contents of UV absorbing compounds,soluble sugar,organic acid,vitamin C and lycopene of tomato fruits,and yield of tomato increased under doubled CO2 concentration.Under the doubled CO2 concentration the effects of lost doses of UV-B radiation could further promote the effects of doubled CO:concentration.However,there is no significant increase in yield of tomato.The best dose of UV-B radiation is about 1.163 kJ.m-2.When the dose of UV-B radiation is more than it,the effects of UV-B will be reduced.

  13. TOMS as a monitor of the ultraviolet radiation environment: Applications to photobiology

    Science.gov (United States)

    Frederick, John E.

    1987-01-01

    The flux of biologically relevant ultraviolet radiation that reaches the surface of the Earth varies with the ozone amount, surface reflectivity, and cloudcover. The Total Ozone Mapping Spectrometer (TOMS) provides information relevant to all three items. A recent application of satellite-based ozone measurements has been to develop climatologies of the biologically significant UV-B radiation reaching the Earth's surface. A growing body of research suggests that UV-B radiation tends to suppress the immune system of laboratory mice. At tropical latitudes, it is likely that parasitical diseases develop most readily in people who have experienced immune system suppression from UV-B exposure. The computed distribution of surface radiation combined with information on disease incidence may clarify the role of UV-B as a suppressor of the human immune system. TOMS used in conjunction with radiative transfer calculations can provide information of relevance in photobiology.

  14. Afterglow emission in Gamma-Ray Bursts: I. Pair-enriched ambient medium and radiative blast waves

    CERN Document Server

    Nava, L; Ghisellini, G; Celotti, A; Ghirlanda, G

    2012-01-01

    Forward shocks caused by the interaction between a relativistic blast wave and the circum-burst medium are thought to be responsible for the afterglow emission in Gamma-Ray Bursts (GRBs). We consider the hydrodynamics of a spherical relativistic blast wave expanding into the surrounding medium and we generalize the standard theory in order to account for several effects that are generally ignored. In particular, we consider the role of adiabatic and radiative losses on the hydrodynamical evolution of the shock, under the assumption that the cooling losses are fast. Our model can describe adiabatic, fully radiative and semi-radiative blast waves, and can describe the effects of a time-varying radiative efficiency. The equations we present are valid for arbitrary density profiles, and also for a circum-burst medium enriched with electron-positron pairs. The presence of pairs enhances the fraction of shock energy gained by the leptons, thus increasing the importance of radiative losses. Our model allows to study...

  15. Ambient Space and Ambient Sensation

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    The ambient is the aesthetic production of the sensation of being surrounded. As a concept, 'ambient' is mostly used in relation to the music genre 'ambient music' and Brian Eno's idea of environmental background music. However, the production of ambient sensations must be regarded as a central...... aspect of the aesthetization of modern culture in general, from architecture, transport and urbanized lifeforms to film, sound art, installation art and digital environments. This presentation will discuss the key aspects of ambient aesthetization, including issues such as objectlessness...

  16. Environmental policy. Ambient radioactivity levels and radiation doses in 1996; Umweltpolitik. Umweltradioaktivitaet und Strahlenbelastung im Jahr 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-10-01

    The report is intended as information for the German Bundestag and Bundesrat as well as for the general population interested in issues of radiological protection. The information presented in the report shows that in 1996, the radiation dose to the population was low and amounted to an average of 4 millisievert (mSv), with 60% contributed by natural radiation sources, and 40% by artificial sources. The major natural source was the radioactive gas radon in buildings. Anthropogenic radiation exposure almost exclusively resulted from application of radioactive substances and ionizing radiation in the medical field, for diagnostic purposes. There still is a potential for reducing radiation doses due to these applications. In the reporting year, there were 340 000 persons occupationally exposed to ionizing radiation. Only 15% of these received a dose different from zero, the average dose was 1.8 mSv. The data show that the anthropogenic radiation exposure emanating from the uses of atomic energy or applications of ionizing radiation in technology is very low. (orig./CB) [Deutsch] Der vorliegende Bericht ueber die `Umweltradioaktivitaet und Strahlenbelastung im Jahr 1996` richtet sich an Bundestag und Bundesrat und darueber hinaus an alle an Fragen des Strahlenschutzes interessierte Buerger. Der Bericht belegt, dass die Strahlenbelastung der Bevoelkerung im Jahr 1996 gering war und insgesamt durchschnittlich 4 Millisievert (mSv) betrug. Dieser Wert war zu 60% auf natuerliche und zu 40% auf kuenstliche Strahlenquellen zurueckzufuehren. Den wesentlichen Beitrag zur natuerlichen Strahlenbelastung lieferte das radioaktive Gas Radon in Wohnungen. Die zivilisatorische Strahlenexposition der Bevoelkerung wurde fast ausschliesslich durch die Anwendung radioaktiver Stoffe und ionisierender Strahlen in der Medizin im Rahmen der Diagnostik hervorgerufen. Hier bestehen nach wie vor Moeglichkeiten zur Reduktion der Strahlenbelastung. Im Jahre 1996 waren 340 000 Personen beruflich

  17. Application of 10B counter with moderator for neutron ambient dose equivalent measurement in radiation monitoring at JINR

    International Nuclear Information System (INIS)

    The possibility to use the instrument based on the 10B-counter (CHM-14) with polyethylene moderator as a dosimeter of the neutron ambient dose equivalent H*(10) in the field of nuclear installations of JINR was investigated. It was shown that the instrument can be used to measure H*(10) of neutrons in the energy range from 0.4 eV to 20 MeV with the uncertainty within 30% due to the dependence of response on neutron energy. The use of the correction factors can extend the energy range of measurement of the neutron dose H*(10) up to hundreds of MeV. The uncertainty due to angular dependence of the instrument response is not more than 35%

  18. Colour Changes on the Surface of the Rock Materials Due to UV-A and UV-B Rays

    Science.gov (United States)

    Binal, Adil; Ayderman, Aykut; Sel, Aylin

    2015-04-01

    The colour of the rocks used in the current buildings, and historical monuments is an important parameter in architecture and engineering. In addition, engineering geologists use the colour in order to identify the weathering class of rock material. The main colour of the stone, especially, are affected by the mineral size, the colour of the primary minerals and matrix material, as well as the colour of the accessory minerals. Due to atmospheric effects, changes in the outer surface colour of the rocks used as siding materials occur with over time. Factors causing the colour change are carbon dioxide (CO2), ozone (O3), sulphate (SO2, SO3) and nitrate (NOx) from the atmosphere with aerosols as well as UV rays from the sun. There is no more work in the literature on colour changes caused by UV-A and UV-B rays. In this study, the effects of ultraviolet in the colour of the surfaces of basalt, limestone, ignimbrite, travertine and sandstone have been simulated with a new experimental device in the laboratory medium. Lutron colour analyser (RGB-1002) was used for the measurements of RGB colours. Colour differences between the beginning and end of tests were determined with the standard practice for calculation of colour tolerances and colour differences from instrumentally measured colour coordinates (ASTM D2244). As a result of the experiments performed, lighten that seem on dark-grey micritic limestone (colour change ratio, CCR: 17.06) and basalt samples (CCR: 8.24) become even visually noticeable. Black and red ignimbrite samples having high porosity were presented the lower rate of colour changes. Finally, colour darkening has been observed in the light-coloured travertine (CCR: 13.8) and sandstone samples (CCR: 20.99).

  19. Ambient Sensors

    NARCIS (Netherlands)

    Börner, Dirk; Specht, Marcus

    2014-01-01

    This software sketches comprise two custom-built ambient sensors, i.e. a noise and a movement sensor. Both sensors measure an ambient value and process the values to a color gradient (green > yellow > red). The sensors were built using the Processing 1.5.1 development environment. Available under th

  20. Det ambiente

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Om begrebet "det ambiente", der beskriver, hvad der sker, når vi fornemmer baggrundsmusikkens diskrete beats, betragter udsigten gennem panoramavinduet eller tager 3D-brillerne på og læner os tilbage i biografsædet. Bogen analyserer, hvorfan ambiente oplevelser skabes, og hvilke konsekvenser det...

  1. Det Ambiente

    DEFF Research Database (Denmark)

    Schmidt, Ulrik

    Det ambiente er iscenesættelsen af en karakteristisk sanseoplevelse, der er kendetegnet ved fornemmelsen af at være omgivet. I dag bliver begrebet om det ambiente mest anvendt i forbindelse med musikgenren ’ambient musik’. Det ambiente er dog ikke essentielt knyttet til det musikalske, men må...... forstås som et betydeligt bredere fænomen i den moderne æstetiske kultur, der spiller en væsentlig rolle i oplevelsen af moderne transportformer, arkitektur, film, lydkunst, installationskunst og digitale multimedieiscenesættelser. En forståelse af det ambiente er derfor centralt for forståelsen af en...... moderne æstetiseret oplevelseskultur i almindelighed. Da det ambiente ikke hidtil har været gjort til genstand for en mere indgående teoretisk behandling, er der dog stor usikkerhed omkring, hvad fænomenet overhovedet indebærer. Hovedformålet med Det ambiente – Sansning, medialisering, omgivelse er derfor...

  2. Screening of UV-B-induced genes from apple peels by SSH: possible involvement of MdCOP1-mediated signaling cascade genes in anthocyanin accumulation.

    Science.gov (United States)

    Peng, Ting; Saito, Takanori; Honda, Chikako; Ban, Yusuke; Kondo, Satoru; Liu, Ji-Hong; Hatsuyama, Yoshimichi; Moriguchi, Takaya

    2013-07-01

    Suppression subtractive hybridization (SSH) was employed to identify candidate genes involved in red coloration in apple peel with the ultraviolet (UV)-B-treated 'Mutsu'. After reverse Northern blotting verification, nearly 80 clones were successfully sequenced. Large portions of the expressed sequence tags (ESTs) are well characterized anthocyanin biosynthesis-related genes, such as chalcone synthase (11A5), flavonol synthase (12F3), anthocyanidin synthase (11H5) and UDP-glycosyl transferase (14A12) whose presence proved the success of SSH. Eight ESTs were selected for quantitative real-time polymerase chain reaction analysis and their expressions were all elevated in 'Induction', further confirming the reliability of the SSH library. One EST, 11F4 (CONSTITUTIVE PHOTOMORPHOGENIC 1: COP1) with putative function in light signal relay was further analyzed in 'Mutsu' and 'Tsugaru', along with MdHY5 (ELONGATED HYPOCOTYL 5: the downstream target of COP1), MdMYB22 (a possible flavonol-specific activator under the regulation of HY5, belonging to the SG7/PRODUCTION OF FLAVONOL GLYCOSIDES family) and MdMYBA. Results showed that MdCOP1, MdHY5, MdMYB22 and MdMYBA were all UV-B inducible genes and anthocyanin accumulation occurred after their increased expressions. Moreover, their expressions and anthocyanin content were enhanced under UV-B plus 17°C treatment. The presence of G box, a known consensus binding site of HY5, in the MdMYBA promoter region implicated that it could be regulated by MdHY5, which was verified by the result of the yeast one-hybrid analysis. Our data suggested that UV-B irradiation would induce the utmost upstream light signaling factor, MdCOP1, which activates MdHY5 signaling by binding to the promoter regions of MdMYBs, and finally leads to the red coloration of apple peels. PMID:23171407

  3. Elevated ROS-scavenging enzymes contribute to acclimation to UV-B exposure in transplastomic tobacco plants, reducing the role of plastid peroxidases.

    Science.gov (United States)

    Czégény, Gyula; Le Martret, Bénédicte; Pávkovics, Dóra; Dix, Philip J; Hideg, Éva

    2016-08-20

    Leaf peroxidases play a key role in the successful acclimation of plants to low UV-B doses. The aim of the present study was to examine whether selective enhancement of alternative chloroplast antioxidant pathways achieved by chloroplast transformation affected the need for peroxidase defense. Transplastomic tobacco lines expressing glutathione reductase in combination with either dehydroascorbate reductase or glutathione-S-transferase in their plastids exhibited better tolerance to supplemental UV-B than wild type plants. After 10days UV treatment, both the maximum and effective quantum yields of PSII decreased in the wild type by 10% but were unaffected in either of the transformed lines. Activities of total peroxidase and ascorbate peroxidase, in addition to dehydroascorbate reductase and gluthatione-S-transferase, were increased by UV in all lines. Gluthatione reductase activity was unaffected by UV in the transplastomic line engineered to have a higher constitutive level of this enzyme, but increased in the two other genotypes. However, the observed more successful acclimation required less activation of peroxidases in the doubly transformed plants than in the wild type and less increase in non-enzymatic hydroxyl radical neutralization in the dehydroascorbate reductase plus glutathione reductase fortified plants than in either of the other lines. These results highlight the fundamental role of efficient glutathione, and especially ascorbate, recycling in the chloroplast in response to exposure of plants to UV-B. They also identify chloroplast localized peroxidases among the large variety of leaf peroxidases as essential elements of defense, supporting our earlier hypothesis on hydrogen peroxide UV-B photo-cleavage as the primary mechanism behind damage. PMID:27448725

  4. Solar ultraviolet radiation affects the activity of ribulose-1, 5-bisphosphate carboxylase-oxygenase and the composition of photosynthetic and xanthophyll cycle pigments in the intertidal green alga Ulva lactuca L.

    NARCIS (Netherlands)

    Bischof, K; Krabs, G; Wiencke, C; Hanelt, D

    2002-01-01

    The effect of solar UV radiation on the physiology of the intertidal green macroalga Ulva lactuca L. was investigated. A natural Ulm community at the shore of Helgoland was covered with screening foils, excluding UV-B or UV-B + UV-A from the solar spectrum. In the sampled material, changes in the ac

  5. The effects of solar ultraviolet-B radiation on the growth and yield of barley are accompanied by increased DNA damage and antioxidant responses

    International Nuclear Information System (INIS)

    There is limited information on the impacts of present-day solar ultraviolet-B radiation (UV-B) on biomass and grain yield of field crops and on the mechanisms that confer tolerance to UV-B radiation under field conditions. We investigated the effects of solar UV-B on aspects of the biochemistry, growth and yield of barley crops using replicated field plots and two barley strains, a catalase (CAT)-deficient mutant (RPr 79/4) and its wild-type mother line (Maris Mink). Solar UV-B reduced biomass accumulation and grain yield in both strains. The effects on crop biomass accumulation tended to be more severe in RPr 79/4 (≈ 32% reduction) than in the mother line (≈ 20% reduction). Solar UV-B caused measurable DNA damage in leaf tissue, in spite of inducing a significant increase in UV-absorbing sunscreens in the two lines. Maris Mink responded to solar UV-B with increased CAT and ascorbate peroxidase (APx) activity. No effects of UV-B on total superoxide dismutase (SOD) activity were detected. Compared with the wild type, RPr 79/4 had lower CAT activity, as expected, but higher APx activity. Neither of these activities increased in response to UV-B in RPr 79/4. These results suggest that growth inhibition by solar UV-B involves DNA damage and oxidative stress, and that constitutive and UV-B-induced antioxidant capacity may play an important role in UV-B tolerance. (author)

  6. Ambient Gestures

    OpenAIRE

    Karam, Maria; Hare, Jonathon; Lewis, Paul; schraefel, m.c.

    2006-01-01

    We present Ambient Gestures, a novel gesture-based system designed to support ubiquitous ‘in the environment’ interactions with everyday computing technology. Hand gestures and audio feedback allow users to control computer applications without reliance on a graphical user interface, and without having to switch from the context of a non-computer task to the context of the computer. The Ambient Gestures system is composed of a vision recognition software application, a set of gestures to be p...

  7. Early exposure to ultraviolet-B radiation decreases immune function later in life

    Science.gov (United States)

    Ceccato, Emma; Cramp, Rebecca L.; Seebacher, Frank; Franklin, Craig E.

    2016-01-01

    Amphibians have declined dramatically worldwide. Many of these declines are occurring in areas where no obvious anthropogenic stressors are present. It is proposed that in these areas, environmental factors such as elevated solar ultraviolet-B (UV-B) radiation could be responsible. Ultraviolet-B levels have increased in many parts of the world as a consequence of the anthropogenic destruction of the ozone layer. Amphibian tadpoles are particularly sensitive to the damaging effects of UV-B radiation, with exposure disrupting growth and fitness in many species. Given that UV-B can disrupt immune function in other animals, we tested the hypothesis that early UV-B exposure suppresses the immune responses of amphibian tadpoles and subsequent juvenile frogs. We exposed Limnodynastes peronii tadpoles to sublethal levels of UV-B radiation for 6 weeks after hatching, then examined indices of immune function in both the tadpoles and the subsequent metamorphs. There was no significant effect of UV-B on tadpole leucocyte counts or on their response to an acute antigen (phytohaemagglutinin) challenge. However, early UV-B exposure resulted in a significant reduction in both metamorph leucocyte abundance and their response to an acute phytohaemagglutinin challenge. These data demonstrate that early UV-B exposure can have carry-over effects on later life-history traits even if the applied stressor has no immediately discernible effect. These findings have important implications for our understanding of the effects of UV-B exposure on amphibian health and susceptibility to diseases such as chytridiomycosis. PMID:27668081

  8. Kinetics of avoidance of simulated solar uv radiation by two arthropods

    Energy Technology Data Exchange (ETDEWEB)

    Barcelo, J.A.; Calkins, J.

    1980-12-01

    There is an increasing likelihood that the solar uv-B radiation (lambda = 280-320 nm) reaching the earth's surface will increase due to depletion of the stratospheric ozone layer. It is recognized that many organisms are insufficiently resistant to solar uv-B to