| 1. |
- Bornman, Janet, et al.
(författare)
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Effects of ultraviolet-radiation on viability of isolated beta-vulgaris and hordeum-vulgare protoplasts
- 1982
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Ingår i: Zeitschrift für Pflanzenphysiologie. - 0044-328X. ; 105:4, s. 297-306
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Tidskriftsartikel (refereegranskat)abstract
- Estimates of viability as measured by vital staining with fluorescein diacetate (FDA) were carried out on freshly isolated and partially aged (16-h-old) B. vulgaris and H. vulgare mesophyll protoplasts following irradiation with UV-B. Damage to the photosynthetic system by UV-B was determined by delayed light emission (DLE). In the case of freshly isolated protoplasts Beta was .apprx. 30% more susceptible than Hordeum following 3 h irradiation, with viability decreasing from 90% to 40%. After storage of protoplasts on ice for 16 h UV-B radiation markedly depressed viability in both species, but in the case of Hordeum there was a substantial initial loss of nearly 70% in viability over the 1st hour of irradiation. The first 10 min of UV-B radiation decreased the intensity of DLE by 40% without appreciably affecting the decay rate. Longer treatment times did not give a proportional effect so that even after 60 min of UV-B the inhibition did not exceed 60%. This suggested that although the enzyme system responsible for FDA hydrolysis may be partially inactivated (viability was 75-80% as compared with 90% in the control), the UV-B did not penetrate the innermost parts of the chloroplasts, but left some thylakoids undamaged.
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| 2. |
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| 3. |
- Andrady, Anthony, et al.
(författare)
-
Environmental effects of ozone depletion and its interaction with climate change: Progress report 2007
- 2008
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Ingår i: Photochemical and Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-9092 .- 1474-905X. ; 7:1, s. 15-27
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Forskningsöversikt (refereegranskat)abstract
- This year theMontreal Protocol celebrates its 20th Anniversary. In September 1987, 24 countries signed the ‘Montreal Protocol on Substances that Deplete the Ozone Layer’. Today 191 countries have signed and have met strict commitments on phasing out of ozone depleting substances with the result that a 95% reduction of these substances has been achieved. The Montreal Protocol has also contributed to slowing the rate of global climate change, since most of the ozone depleting substances are also effective greenhouse gases. Even though much has been achieved, the future of the stratospheric ozone layer relies on full compliance of the Montreal Protocol by all countries for the remaining substances, including methyl bromide, as well as strict monitoring of potential risks from the production of substitute chemicals. Also the ozone depleting substances existing in banks and equipment need special attention to prevent their release to the stratosphere. Since many of the ozone depleting substances already in the atmosphere are long-lived, recovery cannot be immediate and present projections estimate a return to pre-1980 levels by 2050 to 2075. It has also been predicted that the interactions of the effects of the ozone layer and that of other climate change factors will become increasingly important.
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| 4. |
- Andrady, Anthony, et al.
(författare)
-
Environmental effects of ozone depletion and its interactions with climate
- 2009
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Ingår i: Photochemical and Photobiological Sciences. - 1474-9092. ; 8:1, s. 13-22
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Forskningsöversikt (refereegranskat)abstract
- After the enthusiastic celebration of the 20th Anniversary of the Montreal Protocol on Substances that Deplete the Ozone Layer in 2007, the work for the protection of the ozone layer continues. The Environmental Effects Assessment Panel is one of the three expert panels within theMontreal Protocol. This “EEAP” deals with the increase of the UV irradiance on the Earth’s surface and its effects on human health, animals, plants, biogeochemistry, air quality and materials. For the past few years, interactions of ozone depletion with climate change have also been considered. It has become clear that the environmental problems will be long-lasting. In spite of the fact that the worldwide production of ozone depleting chemicals has already been reduced by 95%, the environmental disturbances are expected to persist for about the next half a century, even if the protective work is actively continued, and completed. The latest full report was published in Photochem. Photobiol. Sci., 2007, 6, 201–332, and the last progress report in Photochem. Photobiol. Sci., 2008, 7, 15–27. The next full report on environmental effects is scheduled for the year 2010. The present progress report 2008 is one of the short interim reports, appearing annually.
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| 5. |
- Andrady, Anthony, et al.
(författare)
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Environmental effects of ozone depletion and its interactions with climate change: Progress report, 2016
- 2017
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Ingår i: Photochemical and Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-9092 .- 1474-905X. ; 16:2, s. 107-145
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Tidskriftsartikel (refereegranskat)abstract
- The Parties to the Montreal Protocol are informed by three Panels of experts. One of these is the Environmental Effects Assessment Panel (EEAP), which deals with two focal issues. The first focus is the effects of UV radiation on human health, animals, plants, biogeochemistry, air quality, and materials. The second focus is on interactions between UV radiation and global climate change and how these may affect humans and the environment. When considering the effects of climate change, it has become clear that processes resulting in changes in stratospheric ozone are more complex than previously believed. As a result of this, human health and environmental issues will be longer-lasting and more regionally variable. Like the other Panels, the EEAPproduces a detailed report every four years; the most recent was published as a series of seven papers in 2015 (Photochem. Photobiol. Sci., 2015, 14, 1–184). In the years in between, the EEAP produces less detailed and shorter Progress Reports of the relevant scientific findings. The most recent of these was for 2015 (Photochem. Photobiol. Sci., 2016, 15, 141–147). The present Progress Report for 2016 assesses some of the highlights and new insights with regard to the interactive nature of the direct and indirect effects of UV radiation, atmospheric processes, and climate change. The more detailed Quadrennial Assessment will bemade available in 2018.
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| 6. |
- Barnes, Paul W., et al.
(författare)
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Ozone depletion, ultraviolet radiation, climate change and prospects for a sustainable future
- 2019
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Ingår i: Nature Sustainability. - : Springer Science and Business Media LLC. - 2398-9629. ; 2:7, s. 569-579
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Forskningsöversikt (refereegranskat)abstract
- © 2019, Springer Nature Limited. Changes in stratospheric ozone and climate over the past 40-plus years have altered the solar ultraviolet (UV) radiation conditions at the Earth’s surface. Ozone depletion has also contributed to climate change across the Southern Hemisphere. These changes are interacting in complex ways to affect human health, food and water security, and ecosystem services. Many adverse effects of high UV exposure have been avoided thanks to the Montreal Protocol with its Amendments and Adjustments, which have effectively controlled the production and use of ozone-depleting substances. This international treaty has also played an important role in mitigating climate change. Climate change is modifying UV exposure and affecting how people and ecosystems respond to UV; these effects will become more pronounced in the future. The interactions between stratospheric ozone, climate and UV radiation will therefore shift over time; however, the Montreal Protocol will continue to have far-reaching benefits for human well-being and environmental sustainability.
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| 7. |
- Black, Lucinda J., et al.
(författare)
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In pursuit of vitamin D in plants
- 2017
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Ingår i: Nutrients. - : MDPI AG. - 2072-6643. ; 9:2
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Tidskriftsartikel (refereegranskat)abstract
- Vitamin D deficiency is a global concern. Much research has concentrated on the endogenous synthesis of vitamin D in human skin following exposure to ultraviolet‐B radiation (UV‐B, 280–315 nm). In many regions of the world there is insufficient UV‐B radiation during winter months for adequate vitamin D production, and even when there is sufficient UV‐B radiation, lifestyles and concerns about the risks of sun exposure may lead to insufficient exposure and to vitamin D deficiency. In these situations, dietary intake of vitamin D from foods or supplements is important for maintaining optimal vitamin D status. Some foods, such as fatty fish and fish liver oils, certain meats, eggs, mushrooms, dairy, and fortified foods, can provide significant amounts of vitamin D when considered cumulatively across the diet. However, little research has focussed on assessing edible plant foods for potential vitamin D content. The biosynthesis of vitamin D in animals, fungi and yeasts is well established; it is less well known that vitamin D is also biosynthesised in plants. Research dates back to the early 1900s, beginning with in vivo experiments showing the anti‐rachitic activity of plants consumed by animals with induced rickets, and in vitro experiments using analytical methods with limited sensitivity. The most sensitive, specific and reliable method for measuring vitamin D and its metabolites is by liquid chromatography tandem mass spectrometry (LC‐MS/MS). These assays have only recently been customised to allow measurement in foods, including plant materials. This commentary focuses on the current knowledge and research gaps around vitamin D in plants, and the potential of edible plants as an additional source of vitamin D for humans.
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| 8. |
- Bornman, Janet, et al.
(författare)
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Action spectrum for inhibition by ultraviolet-radiation of photosystem-II activities in spinach thylakoids
- 1984
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Ingår i: Photobiochemistry and Photobiophysics. - 0165-8646. ; 8:5-6, s. 305-313
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Tidskriftsartikel (refereegranskat)abstract
- The effect of UV radiation (half-band width 10 nm) in the wavelength range 248-340 nm on chlorophyll fluorescence from a thin layer of spinach thylakoid suspension was investigated. The parameter most sensitive to UV radiation was the rise time of variable fluorescence. The increase in rise time was proportional to UV photon fluence and was used for the determination of an action spectrum. The action spectrum falls off from a maximum at .apprx. 275 nm towards longer wavelengths and rises from a minimum at 260 nm towards shorter wavelengths. The UV inhibition apparently is mainly on the PS II oxidizing side. Possibly damage is also inflicted to the PS II reaction center.
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| 9. |
- Buffoni Hall, Roberta, et al.
(författare)
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UV-induced changes in pigment content and light penetration in the fruticose lichen Cladonia arbuscula ssp. mitis
- 2002
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Ingår i: Journal of Photochemistry and Photobiology, B: Biology. - 1011-1344. ; 66:1, s. 13-20
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Tidskriftsartikel (refereegranskat)abstract
- The response of the lichen, Cladonia arbuscula (Wallr.) Flot. ssp. mitis (Sandst.) Ruoss to enhanced UV-B (280-315 nm) radiation was investigated with respect to: (a) changes in phenolic content; (b) differential pigment accumulation under visible and UV radiation with increasing distance from thallus apices; and (c) the internal distribution of UV-B radiation within the thallus measured with quartz optical fibres. In a short-term experiment, lichens were exposed for 7 days in a growth chamber to visible light with or without additional UV-B radiation. For a longer term experiment, lichens were grown outdoors under both natural UV radiation, and supplemental UV-A (315–400 nm)+UV-B provided by lamps. Controls were placed under filters that removed the radiation below 290 nm from the natural sunlight. The concentration of total phenolic compounds was measured spectrophotometrically at the termination of the experiments, in different parts of the lichen podetia. UV-exposed lichens showed increased accumulation of phenolics compared to those not grown under UV. At the termination of the long-term experiment, fibre optic measurements of the penetration of radiation into lichen thallus reflected the influence of growth under UV radiation, whereby UV was more strongly attenuated as compared to that in lichens not exposed to enhanced levels of UV-B radiation. Results indicated that in Cladonia, UV-B radiation induces the accumulation of phenolic compounds that may have a protective role. In addition, the morphological distribution of phenolic compounds was different under visible and supplemental UV-B radiation. Internal radiation measurements served to visualise the attenuation of radiation with thallus depth for different wavelengths in the UV-B waveband.
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| 10. |
- Buffoni Hall, Roberta, et al.
(författare)
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Water- and temperature-dependence of DNA damage and repair in the fruticose lichen Cladonia arbuscula ssp mitis exposed to UV-B radiation
- 2003
-
Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317. ; 118:3, s. 371-379
-
Tidskriftsartikel (refereegranskat)abstract
- The induction of cyclobutane pyrimidine dimers (CPDs) by ultraviolet-B radiation (UV-B, 280-315 nm) and repair mechanisms were studied in the lichen Cladonia arbuscula ssp. mitis exposed to different temperatures and water status conditions. In addition, the development and repair of CPDs were studied in relation to the different developmental stages of the lichen thallus podetial branches. Air-dried lichen thalli exposed to UV-B radiation combined with relatively high visible light (HL, 800 mumol m(-2) s(-1); 400-700 nm) for 7 days showed a progressive increase of CPDs with no substantial repair, although HL was present during and after irradiation with UV-B. Fully hydrated lichen thalli, that had not been previously exposed to UV-B radiation for 7 days, were given short-term UV-B radiation treatment at 25degreesC, and accumulated DNA lesions in the form of CPDs, with repair occurring when they were exposed to photoreactivating conditions (2 h of 300 mumol m(-2)s(-1), 400-700 nm). A different pattern was observed when fully hydrated thalli were exposed to short-term UV-B radiation at 2degreesC, in comparison with exposure at 25degreesC. High levels of CPDs were induced at 2degreesC under UV-B irradiation, without significant repair under subsequent photoreactivating light. Likewise, when PAR (300 mumol m(-2)s(-1) ) and UV-B radiation were given simultaneously, the CPD levels were not lowered. Throughout all experiments the youngest, less differentiated parts of the lichen thallus - namely 'tips', according to our arbitrary subdivision - were the parts showing the highest levels of CPD accumulation and the lowest levels of repair in comparison with the older thallus tissue ('stems'). Thus the experiments showed that Cladonia arbuscula ssp. mitis is sensitive to UV-B irradiation in the air-dried state and is not able to completely repair the damage caused by the radiation. Furthermore, temperature plays a role in the DNA damage repairing capacity of this lichen, since even when fully hydrated, C. arbuscula ssp. mitis did not repair DNA damage at the low temperatures.
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| 11. |
- Caldwell, M, et al.
(författare)
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Effects of increased solar ultraviolet-radiation on terrestrial plants
- 1995
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Ingår i: Ambio: a Journal of Human Environment. - 0044-7447. ; 24:3, s. 166-173
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Tidskriftsartikel (refereegranskat)abstract
- Physiological and developmental processes of plants are affected by UV-B radiation, even by the amount of UV-B in present-day sunlight. Plants also have several mechanisms to ameliorate or repair these effects and may acclimate to a certain extent to increased levels of UV-B. Nevertheless, plant growth can be directly affected by UV-B radiation. Response to UV-B also varies considerably among species and also cultivars of the same species. In agriculture, this may necessitate using more UV-B-tolerant cultivars and breeding new ones. In forests and grasslands, this will likely result in changes in species composition; therefore there are implications for the biodiversity in different ecosystems. Indirect changes caused by UV-B-such as changes in plant form, biomass allocation to parts of the plant, timing of developmental phases and secondary metabolism-may be equally, or sometimes more important than damaging effects of UV-B. These changes can have important implications for plant competitive balance, herbivory, plant pathogens, and biogeochemical cycles. These ecosystem-level effects can be anticipated, but not easily predicted or evaluated. Research at the ecosystem level for solar UV-B is barely beginning. Other factors, including those involved in climate change such as increasing CO2, also interact with UV-B. Such reactions are not easily predicted, but are of obvious importance in both agriculture and in nonagricultural ecosystems
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| 12. |
- Caldwell, M M, et al.
(författare)
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Effects of increased solar ultraviolet radiation on terrestrial ecosystems
- 1998
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Ingår i: Journal of Photochemistry and Photobiology, B: Biology. - 1011-1344. ; 46:1-3, s. 40-52
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Tidskriftsartikel (refereegranskat)abstract
- Elevated solar UV-B radiation associated with stratospheric ozone reduction may exert effects on terrestrial ecosystems through actions on plants, microbes, and perhaps on some animals. At the ecosystem level, the effects are less well understood than at the molecular and organismal levels. Many of the most important, yet less predictable, consequences will be indirect effects of elevated UV-B acting through changes in the chemical composition and form of plants and through changes in the abiotic environment. These indirect effects include changes in the susceptibility of plants to attack by insects and pathogens in both agricultural and natural ecosystems; the direction of these changes can result in either a decrease or an increase in susceptibility. Other indirect effects of elevated UV-B include changes in competitive balance of plants and nutrient cycling. The direct UV-B action on plants that results in changes in form or function of plants appears to occur more often through altered gene activity rather than damage. The yield of some crop varieties can be decreased by elevated UV-B, but other varieties are not affected. Plant breeding and genetic engineering efforts should be able to cope with the potential threats to crop productivity due to elevated UV-B. For forest trees, this may be more difficult if effects of elevated UV-B accumulate over several years. All effects of elevated UV-B radiation must be considered in the context of other climate changes such as increased temperature and levels of carbon dioxide, which may alter the UV-B responses, especially for plants. The actions of elevated carbon dioxide and UV-B appear to be largely independent, but interactions occur between changes in UV-B and other factors. Other ecosystem-level consequences of elevated UV-B radiation are emerging and their magnitude and direction will not be easily predicted.
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| 13. |
- Caldwell, Martyn M., et al.
(författare)
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Terrestrial ecosystems, increased solar ultraviolet radiation and interactions with other climatic change factors
- 2003
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Ingår i: Photochemical and Photobiological Sciences. - : Springer Science and Business Media LLC. - 1474-9092 .- 1474-905X. ; 2:1, s. 29-38
-
Forskningsöversikt (refereegranskat)abstract
- Based on research to date, we can state some expectations about terrestrial ecosystem response as several elements of global climate change develop in coming decades. Higher plant species will vary considerably in their response to elevated UV-B radiation, but the most common general effects are reductions in height of plants, decreased shoot mass if ozone reduction is severe, increased quantities of some phenolics in plant tissues and, perhaps, reductions in foliage area. In some cases, the common growth responses may be lessened by increasing CO2 concentrations. However, changes in chemistry of plant tissues will generally not be reversed by elevated CO2. Among other things, changes in plant tissue chemistry induced by enhanced UV-B may reduce consumption of plant tissues by insects and other herbivores, although occasionally consumption may be increased. Pathogen attack on plants may be increased or decreased as a consequence of elevated UV-B, in combination with other climatic changes. This may be affected both by alterations in plant chemistry and direct damage to some pathogens. Water limitation may decrease the sensitivity of some agricultural plants to UV-B, but for vegetation in other habitats, this may not apply. With global warming, the repair of some types of UV damage may be improved, but several other interactions between warming and enhanced UV-B may occur. For example, even though warming may lead to fewer killing frosts, with enhanced UV-B and elevated CO2 levels, some plant species may have increased sensitivity to frost damage. Originally published by the United Nations Environment Programme (UNEP) in "Environmental Effects of Ozone Depletion and its Interactions with Climate Change: 2002 Assessment". See http://www.unep.org/ozone/Publications/index.asp and http://www.earthprint.com/show.htm
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| 14. |
- Härndahl, Ulrika, et al.
(författare)
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The chloroplast small heat shock protein undergoes oxidation-dependent conformational changes and may protect plants from oxidative stress
- 1999
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Ingår i: Cell Stress & Chaperones. - 1466-1268. ; 4:2, s. 129-138
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Tidskriftsartikel (refereegranskat)abstract
- The nuclear-encoded chloroplast-localized Hsp21 is an oligomeric heat shock protein (Hsp), belonging to the protein family of small Hsps and @a-crystallins. We have investigated the effects of high temperature and oxidation treatments on the structural properties of Hsp21, both in purified recombinant form and in transgenicArabidopsis thalianaplants engineered to constitutively overexpress Hsp21. A conformational change was observed for the 300 kDa oligomeric Hsp21 protein during moderate heat stress (=<40oC) ofArabidopsisplants, as judged by a shift to lower mobility in non-denaturing electrophoresis. Similar changes in mobility were observed when purified recombinant Hsp21 protein was subjected to an oxidant. Exposure of Hsp21 protein to temperatures above 70oC led to irreversible aggregation, which was prevented in presence of the reductant dithiothreitol. The transgenic plants that constitutively overexpressed Hsp21 were more resistant to heat stress than were wildtype plants when the heat stress was imposed under high light conditions. These results suggest that the physiological role of Hsp21 involves a response to temperature-dependent oxidative stress.
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| 15. |
- Jansen, Marcel A. K., et al.
(författare)
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Environmental plastics in the context of UV radiation, climate change, and the Montreal Protocol
- 2024
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Ingår i: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 30:4
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Tidskriftsartikel (refereegranskat)abstract
- There are close links between solar UV radiation, climate change, and plastic pollution. UV-driven weathering is a key process leading to the degradation of plastics in the environment but also the formation of potentially harmful plastic fragments such as micro- and nanoplastic particles. Estimates of the environmental persistence of plastic pollution, and the formation of fragments, will need to take in account plastic dispersal around the globe, as well as projected UV radiation levels and climate change factors.image
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| 16. |
- Jansen, Marcel A. K., et al.
(författare)
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Plastics in the environment in the context of UV radiation, climate change and the Montreal Protocol : UNEP Environmental Effects Assessment Panel, Update 2023
- 2024
-
Ingår i: Photochemical and Photobiological Sciences. - : Springer Nature. - 1474-905X .- 1474-9092.
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Tidskriftsartikel (refereegranskat)abstract
- This Assessment Update by the Environmental Effects Assessment Panel (EEAP) of the United Nations Environment Programme (UNEP) considers the interactive effects of solar UV radiation, global warming, and other weathering factors on plastics. The Assessment illustrates the significance of solar UV radiation in decreasing the durability of plastic materials, degradation of plastic debris, formation of micro- and nanoplastic particles and accompanying leaching of potential toxic compounds. Micro- and nanoplastics have been found in all ecosystems, the atmosphere, and in humans. While the potential biological risks are not yet well-established, the widespread and increasing occurrence of plastic pollution is reason for continuing research and monitoring. Plastic debris persists after its intended life in soils, water bodies and the atmosphere as well as in living organisms. To counteract accumulation of plastics in the environment, the lifetime of novel plastics or plastic alternatives should better match the functional life of products, with eventual breakdown releasing harmless substances to the environment.
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| 17. |
- Kalbin, Georgi, et al.
(författare)
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UV-B-induced DNA damage and expression of defence genes under UV-B stress : tissue-specific molecular marker analysis in leaves
- 2001
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Ingår i: Plant, Cell and Environment. - : Wiley. - 0140-7791 .- 1365-3040. ; 24:9, s. 983-990
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the regulatory effect of ultraviolet-B (UV-B) radiation on a number of key stress response genes found in the epidermis and mesophyll of Pisum sativum L., Argenteum mutant. This mutant was chosen for the ease with which the entire epidermis can be removed from the mesophyll tissue. An additional goal was to explore the potential modifying effect of pre-acclimation of plants to UV-B radiation prior to exposure by UV-B during treatment. Results showed that mRNA accumulation was similar during acute short-term UV-B exposure for chalcone synthase (Chs) and short-chain alcohol dehydrogenase (SadA) in both epidermis and mesophyll. In contrast, the mRNA levels differed considerably between tissues for phenylalanine ammonia lyase, chalcone isomerase and lipid transfer protein. After 24 h incubation in visible light after cessation of UV-B exposure, the regulation of mRNA levels also differed between Chs and SadA, the former showing no expression in the epidermis and the latter none in the mesophyll. Acclimation to low UV-B levels before acute exposures resulted in delayed induction of Chs and SadA. Measurements of UV-B-induced cyclobutane pyrimidine dimers (CPDs) showed a greater formation in epidermis than in mesophyll. In addition, acclimation at low UV-B levels resulted in significantly higher basal levels of CPDs than in non-acclimated plants in both mesophyll and epidermis and also in increased damage in concomitant acute exposures. The lack of correlation between the number of CPDs and levels of transcripts for defence genes, indicates that DNA damage does not control transcription of these genes.
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| 18. |
- Larsson, E Helene, et al.
(författare)
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Influence of prior Cd2+ exposure on the uptake of Cd2+ and other elements in the phytochelatin-deficient mutant, cad1-3, of Arabidopsis thaliana
- 2002
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Ingår i: Journal of Experimental Botany. - 0022-0957. ; 53:368, s. 447-453
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Tidskriftsartikel (refereegranskat)abstract
- In order to test the potential effect of prior exposure to different Cd concentrations on Cd uptake and accumulation, plants of Arabidopsis thaliana, including a phytochelatin-deficient mutant, cad1-3, and the wild type, were compared. For Cd uptake experiments, plants were grown for 1 week in nutrient solution containing different Cd concentrations (0, 0.05, 0.1, 0.25, 0.5, and 1.0 muM Cd(NO3)(2)). Thereafter they were subjected to 0.5 muM Cd labelled with Cd-109 for 2 h. Uptake experiments with Cd-109 showed that the phytochelatin-deficient mutant cad1-3, accumulated less Cd than the wild type. Both a lower proportion and lower total amount of absorbed Cd were translocated to the shoot in cad1-3 plants compared to wild-type plants. Cadmium exposure also influenced the amounts of nutrients found, whereby after exposure to high Cd concentrations (0.5, 1.0 muM) during growth, cad1-3 roots contained less Fe, K, Mg, P, and S compared to roots of the wild type. In cad1-3 these elements decreased with increasing Cd concentration. The total Cd content in roots and shoots increased significantly with increasing Cd concentration during growth, although the increase was much less in cad1-3 plants. In time-dependent experiments of Cd uptake carried out between 15 and 120 min on plants not previously exposed to Cd, no significant difference in Cd accumulation between the mutant and wild type were found, although a smaller amount of Cd was translocated to the shoot in cad1-3 plants. The possibility that the differences in Cd accumulation in mutant and wild-type lines may be due to the cytosolic Cd regulation, which is inhibited by the complexation of Cd by phytochelatins, is discussed.
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| 19. |
- Liakoura, V, et al.
(författare)
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The ability of abaxial and adaxial epidermis of sun and shade leaves to attenuate UV-A and UV-B radiation in relation to the UV absorbing capacity of the whole leaf methanolic extracts
- 2003
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317. ; 117:1, s. 33-43
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Tidskriftsartikel (refereegranskat)abstract
- The UV-absorbing capacity (measured as A(310) cm(-2) and A(365) cm(-2) or AUVR cm(-2)) of the shade leaves of four representative evergreen sclerophylls of the Mediterranean region (Quercus coccifera, Q. ilex, Arbutus andrachne and A. unedo) was considerably lower than the corresponding one of sun leaves of the same species. However, fibre optic microprobe measurements showed that adaxial as well as abaxial epidermis of shade leaves of all examined plants, except abaxial epidermis of A. andrachne, were almost as effective as the corresponding ones of the sun leaves in screening out most of the incident UV-B radiation. There is probably a threshold, under which the concentration of the UV-B absorbing compounds in the protective tissues is not furthermore reduced, in spite of the low levels of the stress factor (UV-B radiation) in the environment. On the other hand, the ability of both abaxial and adaxial epidermis to attenuate UV-A radiation, except of adaxial leaf epidermis of Quercus species, depended on the UV absorbing capacity of the whole-leaf extracts, with different correlation patterns between the two Quercus species and the two Arbutus species. This could be explained by the fact that shade leaves showed not only quantitative, but also qualitative differences (higher A(310)/A(365) ratio) in the absorbance of their methanolic extracts compared to these of sun leaves. The results of the present study showed that we should not always correlate the depth of penetration of UV radiation into sun and shade leaves according to the corresponding UV absorbing capacity of the whole leaf methanolic extracts, without taking into account all the anatomical, developmental and biochemical (such as different composition and distribution of the UV-absorbing compounds among the different protective tissues) peculiarities of the leaves of each species.
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| 20. |
- Lindqvist, H, et al.
(författare)
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Influence of time of lifting and storage on the potential photosynthetic efficiency in newly developed leaves of bare-root silver birch and common oak
- 2002
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Ingår i: Scientia Horticulturæ. - 0304-4238. ; 94:1-2, s. 171-179
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Tidskriftsartikel (refereegranskat)abstract
- Silver birch and common oak are known to be sensitive to standard practices in nurseries and they often show poor establishment when transplanted in urban areas. Lifting date and time in cold storage have a strong influence on stress tolerance and plant vitality. This study was carried out to assess the effect of lifting date and storage time on partial photosynthesis measured by chlorophyll fluorescence. Plants were grown at a field site in southern Sweden and were lifted on four occasions, with an interval of 4 weeks during autumn 1997, and were subsequently placed in cold storage for 90, 135 and 180 days. Chlorophyll fluorescence was measured with a pulse-amplified modulation fluorometer in three leaves from the main terminal shoot of three plants from each treatment after 4 weeks growth in a controlled environment room. Four fluorescence parameters were measured: F-m, F-0, F-v/F-m and yield. The results of the yield measurement during illumination, showed that the plants, independently of lifting date and time in storage, were stressed and had a low photosynthetic efficiency. All plants taken up on the two first lifting occasions and those lifted on the third and fourth occasions and stored for 90 and 135 days, and 90 days, respectively, had relatively low values in maximal quantum yield (F-v/F-m, measured after a dark period). The low F-v/F-m was due to high values in F-0, which often indicates malfunction in the reaction centres of photosystem II. This study, together with previous studies, has shown that lifting and storage are strong stress factors for silver birch and common oak. These two events are normal nursery practice. Nurseries need to be aware of the stress effects and attempt to minimise stress by choosing appropriate lifting dates and storage regimes, and thereby minimising tree fatality or poor growth after transplanting.
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| 21. |
- Panagopoulos, Ioannis, et al.
(författare)
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Effects of ultraviolet radiation and visible light on growth, fluorescence induction, ultraweak luminescence and peroxidase activity in sugar beet plants
- 1990
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Ingår i: Journal of Photochemistry and Photobiology, B: Biology. - : Elsevier BV. - 1011-1344. ; 8:1, s. 73-87
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Tidskriftsartikel (refereegranskat)abstract
- Experiments were conducted under growth chamber conditions in order to investigate the importance of the background light quality for the effect of UVB (280–320 nm) radiation on plants. Three week-old sugar beet (Beta vulgaris L.) plants were irradiated for three weeks with enhanced levels of UVB radiation with the following background light conditions: white light (WL) (350–700 nm), WL+UVA (supplementary UVA, 320–400 nm) and "yellow" light (YL) (450–700 nm). The effects of the enhanced UVB radiation were estimated on leaf area, fresh and dry weights of storage roots, chlorophyll and carotenoids, peroxidase activity, fluorescence induction and ultraweak luminescence (UL). Plants grown under YL+UVB died after 10 days. The lowest values for leaf area and fresh and dry weights of storage roots were observed under WL+UVA+UVB conditions. Under WL+UVA and WL+UVA+UVB the decrease in total chlorophyll was mainly a result of the reduction in chlorophyll a. Photosystem II appeared to be inhibited by UVB radiation, while the addition of UVA suggested an ameliorating effect with respect to the rise time kinetics of the chlorophyll fluorescence induction curves. UL of leaves was highest in plants grown under WL+UVB conditions. It is suggested that part of the UL derives from lipid peroxidation. Protective measures may have been afforded by the increase in carotenoids under YL and WL+UVB radiation. Also the leaf peroxidase activity was highest under WL+UVB conditions.
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| 22. |
- Panagopoulos, Ioannis, et al.
(författare)
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Response of sugar beet plants to ultraviolet-B (280-320 nm) radiation and Cercospora leaf spot disease
- 1992
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 84:1, s. 140-145
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Tidskriftsartikel (refereegranskat)abstract
- Sugar beet (Beta vulgaris L.) plants injected with Cercospora beticola Sacc. as well as non-infected plants were grown under visible light with or without ultraviolet-B (UV-B, 280-320 nm) radiation for 40 days. An interaction between UV-B radiation and Cercospora leaf spot disease was observed, resulting in a large reduction in leaf chlorophyll content, dry weight of leaf laminae, petioles and storage roots. Lipid peroxidation in leaves also increased the most under the combined treatments. This was also true for ultraweak luminescence from both adaxial and abaxial leaf surfaces. However, no correlation between lipid peroxidation and ultraweak luminescence was observed. Ultraviolet-B radiation given alone appeared to have either a stimulating effect, giving an increase in dry weight of laminae and reducing lipid peroxidation, or no effect. This lack of effect was seen in the absence of change in dry weight of storage roots and chlorophyll content relative to controls. The study demonstrated a harmful interaction between UV-B radiation and Cercospora leaf spot disease on sugar beet.
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| 23. |
- Panagopoulos, Ioannis, et al.
(författare)
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The effect of UV-B and UV-C radiation on hibiscus leaves determined by ultraweak luminescence and fluorecence induction
- 1989
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 76:4, s. 461-465
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 24. |
- Rozema, J, et al.
(författare)
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The role of UV-B radiation in aquatic and terrestrial ecosystems—an experimental and functional analysis of the evolution of UV-absorbing compounds
- 2002
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Ingår i: Journal of Photochemistry and Photobiology, B: Biology. - 1011-1344. ; 66:1, s. 2-12
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Tidskriftsartikel (refereegranskat)abstract
- We analysed and compared the functioning of UV-B screening pigments in plants from marine, fresh water and terrestrial ecosystems, along the evolutionary line of cyanobacteria, unicellular algae, primitive multicellular algae, charophycean algae, lichens, mosses and higher plants, including amphibious macrophytes. Lichens were also included in the study. We were interested in the following key aspects: (a) does the water column function effectively as an ‘external UV-B filter’?; (b) do aquatic plants need less ‘internal UV-B screening’ than terrestrial plants?; (c) what role does UV screening play in protecting the various plant groups from UV-B damage, such as the formation of thymine dimers?; and (d) since early land ‘plants’ (such as the predecessors of present-day cyanobacteria, lichens and mosses) experienced higher UV-B fluxes than higher plants, which evolved later, are primitive aquatic and land organisms (cyanobacteria, algae, lichens, mosses) better adapted to present-day levels of UV-B than higher plants? Furthermore, polychromatic action spectra for the induction of UV screening pigments of aquatic organisms have been determined. This is relevant for translating ‘physical’ radiation measurements of solar UV-B into ‘biological’ and ‘ecological’ effects. From the action spectra, radiation amplification factors (RAFs) have been calculated. These action spectra allow us to determine any mitigating or antagonistic effects in the ecosystems and therefore qualify the damage prediction for the ecosystems under study. We summarize and discuss the main results based on three years of research of four European research groups. The central theme of the work was the investigation of the effectiveness of the various screening compounds from the different species studied in order to gain some perspective of the evolutionary adaptations from lower to higher plant forms. The induction of mycosporine-like amino acids (MAAs) was studied in the marine dinoflagellate Gyrodinium dorsum, the green algal species Prasiola stipitata and in the cyanobacterium Anabaena sp. While visible (400–700 nm) and long wavelength UV-A (315–400 nm) showed only a slight effect, MAAs were effectively induced by UV-B (280–315 nm). The growth of the lower land organisms studied, i.e. the lichens Cladina portentosa, Cladina foliacaea and Cladonia arbuscula, and the club moss Lycopodiumannotinum, was not significantly reduced when grown under elevated UV-B radiation (simulating 15% ozone depletion). The growth in length of the moss Tortula ruralis was reduced under elevated UV-B. Of the aquatic plants investigated the charophytes Chara aspera showed decreased longitudinal growth under elevated UV-B. In the ‘aquatic higher plants’ studied, Ceratophyllum demersum, Batrachium trichophyllum and Potamogeton alpinus, there was no such depressed growth with enhanced UV-B. In Chara aspera, neither MAAs nor flavonoids could be detected. Of the terrestrial higher plants studied, Fagopyrum esculentum, Deschampsia antarctica, Vicia faba, Calamagrostis epigejos and Carex arenaria, the growth of the first species was depressed with enhanced UV-B, in the second species length growth was decreased, but the shoot number was increased, and in the latter two species of a dune grassland there was no reduced growth with enhanced UV-B. In the dune grassland species studied outdoors, at least five different flavonoids appeared in shoot tissue. Some of the flavonoids in the monocot species, which were identified and quantified with HPLC, included orientin, luteolin, tricin and apigenin. A greenhouse study with Vicia faba showed that two flavonoids (aglycones) respond particularly to enhanced UV-B. Of these, quercetin is UV-B inducible and mainly located in epidermal cells, while kaempferol occurs constitutively. In addition to its UV-screening function, quercetin may also act as an antioxidant. Polychromatic action spectra were determined for induction of the UV-absorbing pigments in three photosynthetic organisms, representing very different taxonomic groups and different habitats. In ultraviolet photobiology, action spectra mainly serve two purposes: (1) identification of the molecular species involved in light absorption; and (2) calculation of radiation amplification factors for assessing the effect of ozone depletion. Radiation amplification factors (RAFs) were calculated from the action spectra. In a somewhat simplified way, RAF can be defined as the percent increase of radiation damage for a 1% depletion of the ozone layer. Central European summer conditions were used in the calculations, but it has been shown that RAF values are not critically dependent on latitude or season. If only the ultraviolet spectral region is considered, the RAF values obtained are 0.7 for the green alga Prasiola stipitata, 0.4 for the dinoflagellate Gyrodinium dorsum, and 1.0 for the cyanobacterium Anabaena sp. In the case of P. stipitata, however, the effect of visible light (PAR, photosynthetically active radiation, 400–700 nm) is sufficient to lower the RAF to about 0.4, while the PAR effect for G. dorsum is negligible. RAFs for some damage processes, such as for DNA damage (RAF=2.1 if protective effects or photorepair are not considered [1]), are higher than those above. Our interpretation of this is that if the ozone layer is depleted, increased damaging radiation could overrule increased synthesis of protective pigments. In addition to investigating the functional effectiveness of the different screening compounds, direct UV effects on a number of key processes were also studied in order to gain further insight into the ability of the organisms to withstand enhanced UV-B radiation. To this end, the temperature-dependent repair of cyclobutane dimers (CPD) and (6–4) photoproducts induced by enhanced UV-B was studied in Nicotiana tabacum, and the UV-B induction of CPD was studied in the lichen Cladonia arbuscula [2]. Also, photosynthesis and motility were monitored and the response related to the potential function of the screening compounds of the specific organism.
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