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Many determinants of vitamin D status have been well-described, yet supplementation guidelines largely follow a one-size-for-all model and deficiency remains common. We hypothesised that accounting accurately for ultraviolet-B (UVB) radiation and considering interactions could advance understanding of vitamin D status. Asian, Black, and White participants from the UK Biobank cohort were included (N = 438,978). The Tropospheric Emission Monitoring Internet Service provided UVB data which we linked to participants' place of residence. UVB dose over 135 days prior to blood draw was weighted and added, yielding cumulative and weighted UVB (CW-D-UVB). The association between 25(OH)D and selected variables was assessed in multivariable linear regression models with and without interactions, stratified by ethnicity. Predictors were ranked using standardised β-coefficients. Median 25(OH)D differed by ethnicity (Asian: 25.4 nmol/L (10.2 ng/mL), Black: 30.6 nmol/L (12.2 ng/mL), White: 47.9 nmol/L (19.2 ng/mL), p-value < 0.001). CW-D-UVB was strongly associated with 25(OH)D in all ethnicities. It was the most important predictor in White (β Asian = 0.15, β Black = 0.20, β White = 0.35), whereas supplementation was in Asian and Black participants (β Asian = 0.30, β Black = 0.24, β White = 0.21). We identified statistically significant interactions between BMI:supplementation (all), CW-D-UVB:sex (Asian and White), and CW-D-UVB:age (Black and White), and in White population between CW-D-UVB and supplementation, BMI, and cholesterol. Vitamin D deficiency was widespread, particularly among non-White individuals. UVB was a strong predictor of 25(OH)D and the effect was modified by other factors. Findings suggest that accurately measured ambient-UVB radiation and interactions could improve 25(OH)D prediction models, and support personalised approaches to vitamin D optimisation. [ABSTRACT FROM AUTHOR]

• Omega-3 fatty acids suppress the increase in TEWL due to UV-B irradiation. • Omega-3 fatty acids mitigate damage to the granular layer caused by UV-B irradiation. • Omega-3 fatty acids regulate accelerated turnover due to UV-B irradiation. Mice fed a diet containing an adequate amount of ω-3 fatty acids (ω-3 Adq) or a deficient diet (ω-3 Def) were irradiated with ultraviolet-B (UV-B) and were measured daily changes in transepidermal water loss (TEWL). TEWL was significantly increased in ω-3 Def mice with repeated UV-B irradiation, but this increase was significantly reduced in ω-3 Adq mice. The epidermal layers revealed thickening of the spinous and basal layers induced by UV-B irradiation in both groups. Moreover, the ω-3 Def mice had a disturbed epidermal structure and a coarser stratum corneum. And the granule cell layer is significantly reduced, and abnormal layer formation (parakeratosis) occurred in the stratum corneum. These results suggest that continuous UV-B irradiation promotes epidermal turnover and leads to epidermal thickening, but ω-3 fatty acids protect the body from UV-B-induced stress. [ABSTRACT FROM AUTHOR]

Abstract Ozone layer depletion leads to elevated ultraviolet-B (UV-B) radiation, which affects plant growth; however, little is known about the relationship between root growth and signaling molecules in roots. Therefore, in this work, simulated UV-B radiation was used to study the effects of elevated UV-B radiation on root growth of soybean seedlings and changes in the content of signaling molecules in roots. The results showed that compared with the control, the 2.63 kJ m−2 d−1 and 6.17 kJ m−2 d−1 elevated UV-B radiation treatments inhibited root growth, and root growth parameters (total root length, root surface area, root volume, average diameter, root tip number, and root dry weight) all decreased. For root signaling molecules, the content of nitric oxide, reactive oxygen species, abscisic acid, salicylic acid, and jasmonic acid increased, and the content of auxin, cytokinin, and gibberellin decreased. The above indices changed more significantly under the 6.17 kJ m−2 d−1 treatment. After withdrawal of the exposure, the above indices could be restored to a certain extent. These data indicated that UV-B radiation interfered with root growth by affecting the content of signaling molecules in roots, and the degree of the effects was related to the intensity of UV-B radiation. The results from this study provide a theoretical basis for studying the preliminary mechanism of elevated UV-B radiation on root growth and possible pathways that can mitigate UV-B radiation damage for root growth. One sentence summary The effects of elevated UV-B on root growth of soybean seedlings were regulated by signaling molecules, and the degree of the effects was related to the intensity of UV-B radiation. Graphical abstract fx1 Highlights • Study UV-B effects on root growth from perspective of chemical signaling molecules. • The UV-B effects on roots were mediated by chemical signaling molecules. • Chemical signaling molecules NO, ROS, and hormones, affect root growth. [ABSTRACT FROM AUTHOR]

An outdoor experiment was carried out to investigate the effects of elevated ultraviolet-B radiation on the chemical composition of wheat straw, and an indoor incubation test was conducted to study the effects of the amendment of the straw on soil N2O emission. Outdoor experiment showed that the enhanced UV-B decreased the aboveground biomass of wheat, increased the lignin and total N contents of wheat straw by 94.2% and 12.3%, respectively, and decreased the C/ N ratio of the straw. Incubation test showed that comparing with the amendment of conventional wheat straw, the amendment of wheat straw received enhanced UV-B radiation during plant growth increased soil N2O emission under the dry-land and flooded conditions significantly. When nitrate was applied, the soil N2O emission in the treatment with straw received enhanced UV-B radiation during plant growth was 3.2 times higher than that with the conventional straw under dry-land condition, but did not differ significantly under flooded condition. The amendment of wheat straw which received UV-B radiation during plant growth had no significant effects on soil respiration. [ABSTRACT FROM AUTHOR]

Abstract: Phenogenetic response of silver birch populations and half-sib families to separate and combined elevated ozone (O3) concentrations and ultraviolet-B (UV-B) radiation dozes was studied at juvenile age in the climatic chambers. Significant population and family effects were found for seedling height, lamina width, and leaf damage. The exposure to UV-B radiation decreased genetic variation at the stage of seed germination. Complex exposure to UV-B and O3 caused an increase of genetic variation at the stage of intensive seedling growth: seedling height genetic variation in separate treatments increased from 23.7–38.6 to 33.7–65.7%, the increase for lamina width was from 10.2–13.9 to 13.6–31.8%. Different populations and families demonstrated differing response to elevated complex UV-B and O3 exposure. Changes of genetic intra-population variation were population-specific. Such changes in genetic variation under the impact of stressors can alter adaptation, stability, and competitive ability of regenerating populations in a hardly predictive way. [Copyright &y& Elsevier]

The increase in ground level UV-B radiation as a result of stratospheric ozone depletion may have major deleterious effects on crop photosynthesis and productivity. Plants are exposed to UV-B and other xenobiotics simultaneously in today''s industrialized world. The present studies were undertaken to see the effect of dual stress of UV-B and Cd2+ exposure on the growth of wheat (Triticum aestivum L.) seedlings. The plants grown in 0.25, 0.5, 1.0, 2.5, and 5.0 ppm Cd2+-supplemented medium were exposed to UV-B for 30 min (2 J, 0.4 mW/cm2) per day. After 5 and 10 days of treatment the combined stress of UV-B and Cd2+ resulted in reduction of biomass yield, growth, and chlorophyll content and changes in protein, free amino acid, starch, and total reducing sugar content. These data support the assumption that UV-B 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. The results also indicate that the adverse effects of one stress may be modulated in the presence of other stresses. [Copyright &y& Elsevier]

Impacts of UV-B radiation on the glutathione level were studied in mature Scots pine needles ( Pinus sylvestris L.) during the third season of a UV-B field experiment. Studies were made on 4-week-old (July) to 14-week-old (September) current-year needles and 3-year-old needles which had their third UV-B-exposure season in progress. Depending on the season and the year (1996–98), the supplemental UV-B dose varied from 0.92 to 5.09 kJ m −2 day −1 UV-B BE compared to 0.47–2.44 kJ m −2 day −1 UV-B BE under the ambient treatment. Fully grown UV-B-treated current-year needles showed lower total glutathione concentrations after the vegetation period in September, whereas in UV-B-treated 3-year-old needles the total glutathione content was significantly lower and the proportion of oxidized glutathione (GSSG%) 56% higher in July. The significant differences in total glutathione in current-year needles in September and in active 3-year-old needles in July seem to indicate that the effect of enhanced UV-B radiation on glutathione status could be cumulative. [ABSTRACT FROM AUTHOR]

Patterns of environmental change in the biosphere include concurrentand sequential combinations of increasing ultraviolet (UV-B) and ozone (O3) at increasing carbon dioxide (CO2) levels; long-term changes are resulting mainly from stratospheric O3 depletion, greater tropospheric O3 photochemical synthesis, and increasing CO2 emissions. Effects of selectedcombinations were evaluated in tomato (Lycopersicon esculentum cv. New Yorker) seedlings using sequential exposures to enhanced UV-B radiation and O3 in differential CO2 concentrations. Ambient (7.2 kJ m-2 day-1) or enhanced (13.1 kJ m-2 day-1) UV-B fluences and ambient (380 Mul l-1) or elevated (600 Mul l-1) CO2were imposed for 19 days before exposure to 3-day simulated O3 episodes with peak concentrations of 0.00, 0.08, 0.16 or 0.24 Mul l-1 O3 in ambient or elevated CO2. CO2 enrichment increased dry mass, leaf area, specific leaf weight, chlorophyll concentration and UV-absorbing compounds per unit leaf area. Exposure to enhanced UV-B increased leaf chlorophyll and UV-absorbing compounds but decreased leaf area and root/shoot ratio. O3 exposure generally inhibited growth and leaf photosynthesis and did not affect UV-absorbing compounds. The highest dose of O3 eliminated the stimulating effect of CO2 enrichment after ambient UV-B pre-exposure on leaf photosynthesis. Pre-exposure to enhanced UV-B mitigated O3 damage to leaf photosynthesis at elevated CO2. [ABSTRACT FROM AUTHOR]

Ultraviolet-B radiation (UV-B: 290-315 nm) is expected to increase as the result of stratospheric ozone depletion. Within the environmental range, UV-B effects on host plants appear to be largely a functionof photomorphogenic responses, while effects on fungal pathogens mayinclude both photomorphogenesis and damage. The effects of increasedUV-B on plant-pathogen interactions has been studied in only a few pathosystems, and have used a wide range of techniques, making generalisations difficult. Increased UV-B after inoculation tends to reducedisease, perhaps due to direct damage to the pathogen, although responses vary markedly between and within pathogen species. Using Septoria tritici infection of wheat as a model system, it is suggested thateven in a species that is inherently sensitive to UV-B, the effects of ozone depletion in the field are likely to be small compared with the effects of variation in UV-B due to season and varying cloud. Increased UV-B before inoculation causes a range of effects in differentsystems, but an increase in subsequent disease is a common response,perhaps due to changes in host surface properties or chemical composition. Although it seems unlikely that most crop diseases will be greatly affected by stratospheric ozone depletion within the limits currently expected, the lack of a detailed understanding of the mechanisms by which UV-B influences plant-pathogen interactions in most pathosystems is a significant limit to such predictions. [ABSTRACT FROM AUTHOR]

Adverse biological effects of ultraviolet-B (UV-B) radiation have been well documented for phytoplankton and zooplankton in both marine and freshwater ecosystems. However, investigations of interactions between UV-B and anthropogenic toxicants have focused primarily on the chemical interactions between UV-B and the toxicant. Here we investigate the potential for UV-B to increase the sensitivity of the rotifer Brachionus calyciflorus to either acute pentachlorophenol (PCP) or mercury toxicity, independent of UV-B effects on these toxicants. UV-B increased the toxicity of PCP and mercury to B. calyciflorus as much as five-fold, depending on duration of UV-B exposure and toxicant concentration. Reductions in the LC50 of up to 60% were also seen for both toxicants. UV-B alone effectively eliminated B. calyciflorus reproduction and reduced ingestion by up to 90%. These results demonstrate the potential for UV-B to increase rotifer sensitivity toanthropogenic stressors independent of photochemical reactions with toxicants. [ABSTRACT FROM AUTHOR]

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 plantswas 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. (c) 1999 Elsevier Science Ltd. [ABSTRACT FROM AUTHOR]

The current knowledge on conifer responses to enhanced ultraviolet-B(UV-B) radiation is mainly based on greenhouse or growth chamber experiments of one growing season in duration. However, the biomass losses observed in greenhouses do not occur in field-grown trees in theirnatural habitats. Moreover, the majority of the 20 conifer species studied have been 1-year-old seedlings, and no studies have been undertaken on mature trees. Fully grown needles, with their glaucous waxy surfaces and thick epidermal cells with both soluble and wall-bound UV-B screening metabolites, are well protected against UV-B radiation.However, it is not known whether these are sufficient protectants inyoung emerging needles or during the early spring period of high UV-B levels reflected from snow. In order to understand all the mechanisms that result in the protection of conifer needles against UV-B radiation, future research should focus on the epidermal layer, separating the waxes, cuticle and epidermal and hypodermal cells. Parallel studies should consist of wall-bound and soluble secondary metabolite analysis, antioxidant measurements and microscopic observations. [ABSTRACT FROM AUTHOR]

The impact on plant growth of the simultaneously changing factors ofthe global climate, rising tropospheric O3 concentrationsand increasing UV-B radiation fluxes, has been tested in a combined glasshouse and growth chamber experiment. The saltmarsh grass speciesElymus athericus was sequentially fumigated for two weeks with O3 and for another two weeks irradiated with UV-B (vv). Exposure to elevated UV-B did not negatively affect photosynthesis or plant growth. Fumigation with O3 had a depressing effect on net photosynthesis, the number and biomass of flowers, the number of leaves and the number of shoots. O3-induced damage only was observed in plants which had been fumigated during the last two weeks of the experiment. Since interactive responses were not observed, results suggest different primary target sites for O3 and UV-Bwithin the plant. [ABSTRACT FROM AUTHOR]