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The ultraviolet–B (UV–B) radiation is harmful to the aquatic organisms. The UV–B protective properties of leaves and seeds of herb Achyranthes aspera were evaluated in Clarias batrachus. Fish were fed with four diets—EFL1, EFL2 containing 0.25 and 0.5% leaves, EFS containing 0.5% seeds and control, CF. After 83 days of feeding, fish were exposed to UV–B (157 µW/cm2) for 7 days at the rate of 15 min/day. One batch of fish in each treatment was kept unexposed. Significantly higher final weight was found in EFS followed by EFL2 and EFL1 treatments. It was higher in unexposed fish compared to the exposed ones. Among exposed fish, significantly higher lysozyme was found in EFS and myeloperoxidase in EFS and EFL2 compared to others. Nitric oxide synthase and superoxide dismutase levels were significantly higher in liver and head kidney of EFS diet fed fish compared to others. Thiobarbituric acid reactive substances (TBARS) and carbonyl protein levels were minimum in EFS followed by EFL2. The independent sample t-test showed that nitric oxide synthase was significantly higher and myeloperoxidase and TBARS levels were significantly lower in unexposed group compared to the exposed fish in respective treatment. There were up-regulations of TNF-α, iNOS, NF-kB, BAX, Cytochrome c, SOD-c, Caspase 3, Caspase 9, BCL2 in liver and head kidney of leaves and seeds incorporated diets fed fish compared to control. Supplementation of A. aspera seeds and leaves at 0.5% level in diets gave UV–B protection to the fish. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the photoprotective potential of Viburnum grandiflorum (VG) against ultraviolet-B radiation-induced responses in HaCaT cells. The HaCaT cells were pretreated with VG prior ultraviolet-B (UVB)-radiation exposure and were further examined for lipid peroxidation, enzymatic antioxidant activity, % reactive oxygen species, DNA damage, mitochondrial membrane potential and for inflammatory, and apoptotic signaling markers such as tumor necrosis factor-alpha, nuclear factor kappa B, interleukin-1 (IL-1), IL-6, cyclooxygenase-2, p53, caspase-3/9, cytochrome-c, Bax, and Bcl-2. The VG pretreatment in UVB exposed cells shows significantly regulated both inflammatory as well as apoptotic signaling cascades. Our findings suggest that VG may be functional against UVB-induced photo-damages. [ABSTRACT FROM AUTHOR]

Background: Korean ginseng (Panax ginseng Meyer) is a traditional herbal medicine used worldwide today. Ginsenoside Rd (Rd), one of its main ginsenosides, has been ascertained to have various pharmacological efficacies including neuroprotective and anti-inflammatory activities. Objectives: This work assesses the antioxidant and protective potentials of Rd against ultraviolet (UV)-B-induced skin photooxidative stress in HaCaT keratinocytes. Materials and Methods: Cell viability was detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Intracellular reactive oxygen species (ROS) were measured using dichlorodihydrofluorescein diacetate. Promatrix metalloproteinase-2 (proMMP-2) activity and protein were detected using gelatin zymography and western analysis. Total glutathione (GSH) content and total superoxide dismutase (SOD) activity were spectrophotometrically determined. Results: Rd, at varying concentrations non-toxic to HaCaT keratinocytes, attenuated the UV-B-induced ROS generation. Rd at 5, 12, and 30 μM attenuated the UV-B-induced proMMP-2 gelatinolytic activities to 59.3% ± 9.5%, 41.3% ± 9.5%, and 13.1% ± 8.9%, respectively, of those of the non-treated control cells. It could also diminish the UV-B-induced proMMP-2 protein levels. Rd at 5, 12, and 30 μM augmented the UV-B-reduced total SOD activities to 1.6 ± 0.2-, 2.4 ± 0.3-, and 3.2 ± 0.2-fold of those of the non-treated control cells, respectively. Rd could up-regulate the UV-B-reduced total GSH. Conclusion: Rd has counteracting properties against elevated ROS and proMMP-2 and attenuated GSH and SOD under UV-B irradiation, implying that it possesses a protective activity against photoaging possibly through up-regulating antioxidant components. These findings suggest that Rd can be considered as a novel natural resource for anti-photoaging functional cosmetics. [ABSTRACT FROM AUTHOR]

Ultraviolet-B radiation can result in deleterious effects on many plant growth processes. In clonal plants, resources and hormones are often shared between connected ramets to deal with various environments. However, little is known about whether and how clonal integration influences the ability of clonal plants to respond to UV-B radiation. In this paper, ramet pairs of Duchesnea indica were either connected by stolons or disconnected by stolon interruption. One of the ramet in the pair was exposed to elevated UV-B radiation. Water transport rate and several growth, photosynthetic and biochemical parameters were measured. When ramets were connected and exposed to heterogeneous UV-B radiation, the velocity of water transportation from the UV-B treated ramet to its connected sister ramet was markedly lower. Moreover, stolon connection resulted in an increase of biomass and ramet number in the UV-B stressed part of the clonal fragments at the expense of that in the UV-B unstressed part. In addition, the contents of chlorophylls and UV-B absorbing compounds were shared between connected ramets under heterogeneous UV-B radiation. Gas exchange and chlorophyll fluorescence parameters of the UV-B stressed ramets were impaired by supplemental UV-B radiation in Duchesnea indica. Clonal integration significantly reduced the stressful impact imposed by enhanced UV-B radiation at a cost to the whole clone. [ABSTRACT FROM AUTHOR]

Gradients in cuticle lightness of ectotherms have been demonstrated across latitudes and elevations. Three key hypotheses have been used to explain these macroecological patterns: the thermal melanism hypothesis (TMH), the melanism‐desiccation hypothesis (MDH) and the photo‐protection hypothesis (PPH). Yet the broad abiotic measures, such as temperature, humidity and UV‐B radiation, typically used to detect these ecogeographical patterns, are a poor indication of the microenvironment experienced by small, cursorial ectotherms like ants.We tested whether these macroecological hypotheses explaining cuticle lightness held at habitat and microclimatic level by using a vertical gradient within a tropical rainforest.We sampled 222 ant species in lowland, tropical rainforest across four vertical strata: subterranean, ground, understory and canopy. We recorded cuticle lightness, abundance and estimated body size for each species and calculated an assemblage‐weighted mean for cuticle lightness and body size for each vertical stratum. Abiotic variables (air temperature, vapour pressure deficit and UV‐B radiation) were recorded for each vertical stratum.We found that cuticle lightness of ant assemblages was vertically stratified: ant assemblages in the canopy and understory were twice as dark as assemblages in ground and subterranean strata. Cuticle lightness was not correlated with body size, and there was no support for the TMH. Rather, we attribute this cline in cuticle lightness to a combination of the MDH and the PPH.Our findings indicate that broad macroecological patterns can be detected at much smaller spatial scales and that microclimatic gradients can shape trait variation, specifically the cuticle lightness of ants. These results suggest that any changes to microclimate that occur due to land‐use change or climate warming could drive selection of ants based on cuticle colour, altering assemblage structure and potentially ecosystem functioning. [ABSTRACT FROM AUTHOR]

The present study examines the impact of ultraviolet-B (UV-B) radiation stress on commercially significant microalga for biofuel application. Experimental alga Botryococcus braunii was treated under different doses of artificially enhanced UV-B radiation. The organism was treated under high dose rates of 1 and 5 Wm-2 with altered time durations of 15, 30, 45 and 60 min. It showed large variations in the growth characteristics analysed. The rate of whole-cell photosynthetic oxygen evolution showed steep drop in high dose compared to low dose-treated cultures. As a result, level of photosynthetic pigment chlorophyll a content decreased drastically while carotenoid level invariably increased. Consequently, the level of primary metabolites such as total carbohydrate, protein and lipid was drastically reduced under high dose while marginal decrement was observed at lowest dose of UV-B radiation. Overall, the impact of UV-B radiation on B. braunii led to a drop in protective mechanisms with associated decline in growth and cellular imbalance at high intensity studied. [ABSTRACT FROM AUTHOR]

Abstract Organisms suffer more harmful ultraviolet radiation in the Antarctica due to the ozone layer destruction. Bryophytes are the dominant flora in the Antarctic continent. However, the molecular mechanism of Antarctic moss adaptation to UV-B radiation remains unclear. In the research, the transcriptional profiling of the Antarctic moss Pohlia nutans under UV-B radiation was conducted by Illumina HiSeq2500 platform. Totally, 72,922 unigenes with N 50 length of 1434 bp were generated. Differential expression analysis demonstrated that 581 unigenes were markedly up-regulated and 249 unigenes were significantly down-regulated. The gene clustering analysis showed that these differentially expressed genes (DEGs) includes several transcription factors, photolyases, antioxidant enzymes, and flavonoid biosynthesis-related genes. Further analyses suggested that the content of malondialdehyde (MDA), the activities of several antioxidant enzymes (i.e., catalase, peroxidase, and glutathione reductase) were significantly enhanced upon UV-B treatment. Furthermore, the content of flavonoids and the gene expression levels of their synthesis-related enzymes were also markedly increased when plants were exposed to UV-B light. Therefore, these results suggested that the pathways of antioxidant enzymes, flavonoid synthesis and photolyases were the main defense systems that contributed to the adaption of Pohlia nutans to the enhanced UV-B radiation in Antarctica. Highlights • The transcriptome analysis of Pohlia nutans under UV-B treatment was performed using RNA-seq technology. • The expression of transcription factor, antioxidant enzyme, flavonoid-related enzyme were up-regulated after UV-B treatment. • The contents of MDA and flavonoids, and the activities of antioxidant enzymes were markedly increased after UV-B treatment. • This study reveals the important role of ROS-scavenging system in the process of Antarctic mosses adapting to UV-B radiation. [ABSTRACT FROM AUTHOR]

Abstract It has been suggested that accumulation of flavonoids could be a key step in development of plant tolerance to different environmental stresses. Moreover, it has been recognized that abiotic stresses such as drought and UV-B radiation (280–315 nm) induce phenolic compound accumulation, suggesting a role for these compounds in drought tolerance. The aim of the present study was to evaluate the effect of UV-B exposure on chili pepper (Capsicum annuum , cv. 'Coronel') plant performance, phenolic compound production, and gene expression associated with response to subsequent drought stress. Additionally, the phenotypic response to drought stress of these plants was studied. UV-B induced a reduction both in stem length, stem dry weight and number of floral primordia. The largest reduction in these variables was observed when combining UV-B and drought. UV-B-treated well-watered plants displayed fructification approximately 1 week earlier than non-UV-B-treated controls. Flavonoids measured epidermally in leaves significantly increased during UV-B treatment. Specifically, UV-B radiation significantly increased chlorogenic acid and apigenin 8-C-hexoside levels in leaves and a synergistic increase of luteolin 6-C-pentoside-8-C-hexoside was obtained by UV-B and subsequent drought stress. Gene expression of phenylalanine ammonia lyase (PAL) and chalcone synthase (CHS) genes also increased during UV-B treatments. On the other hand, expression of genes related to an oxidative response, such as mitochondrial Mn-superoxide dismutase (Mn- SOD) and peroxidase (POD) was not induced by UV-B. Drought stress in UV-B-treated plants induced mitochondrial Mn- SOD gene expression. Taken together, the UV-B treatment did not induce significant tolerance in plants towards drought stress under the conditions used. Highlights • UV-B reduced stem length, stem dry weight, and number of floral primordia in pepper. • Even larger reductions were observed when combining UV-B and drought. • Epidermal flavonoids in leaves increased during UV-B treatment. • UV-B increased chlorogenic acid and apigenin 8-C-hexoside levels in leaves. • UV-B increased phenylalanine ammonia lyase and chalcone synthase gene expression. [ABSTRACT FROM AUTHOR]

Abstract At temperate latitudes environmental factors such as irradiance, including ultraviolet-B radiation (UV-B, 280–315 nm), temperature and day length vary widely over the course of a year in a concerted way. In the present study physiological acclimation of photoprotection, growth and development of the model organism Arabidopsis thaliana were correlated to these strongly but gradually changing conditions in a one year field study. Plants were sown in the field avoiding any manipulation (and abrupt change) during their life. Developmental rate was strongly dependent on prevailing temperature. Moderate signs of light stress in form of photoinhibition at photosystem II were significantly related to solar irradiances while amount of DNA damage was low and not correlated to UV-B irradiance. Although all the markers were hypothesized to primarily react to radiation, multiple regression analysis showed at least a similarly strong influence of temperature as that of light. Especially for the classical UV screening compounds a positive correlation to UV-B radiation during the course of the year was absent, whereas there was a significant negative correlation between temperature and quercetin content. The sum of violaxanthin cycle pigments was correlated to both, irradiance and temperature, but with opposite sign. Epidermal UV-B transmittance was also much better related to air temperature than to UV-B irradiance. The data show that under natural conditions temperature has at least a similar importance for photoprotective acclimation and partially also for photosensitivity as solar irradiance. Highlights • Growth and phenology of Arabidopsis thaliana was followed over a year in the field. • UV absorbing pigments were significantly correlated to temperature but not to UV-B. • Only moderate photoinhibition and DNA damage were found. [ABSTRACT FROM AUTHOR]

Vitamin D plays a central role in calcium homeostasis of most vertebrates, and is obtained in different species through diet, dermal synthesis, or a combination of both. The aim of this study was to determine the predominant routes of Vitamin D synthesis in three disparate species, brown kiwi (Apteryx mantelli), tuatara (Sphenodon punctatus), and New Zealand sea lions (Phocarctos hookeri). We surveyed plasma concentrations of 25-hydroxyvitamin D2 and D3, analysed environmental conditions and life history factors, and determined the ability of skin samples to synthesise Vitamin D3 on exposure to ultraviolet-B radiation. There was variation in the plasma/serum 25-hydroxyvitamin D3 concentrations between and within the species studied, with wild kiwi having the lowest concentrations and NZ sea lions the highest. Kiwi skin produced small but measurable amounts of Vitamin D3, while tuatara skin produced Vitamin D3 concentrations higher than that of kiwi. New Zealand sea lion skin produced the highest amount of Vitamin D3 and differed from the other two species in this study in that Vitamin D3 was present in skin before UV-B exposure. The results from this study show that all three species studied retained the ability to use both dietary and dermal sources of Vitamin D, although there was interspecies variation in the magnitude of dermal synthesis. Comparisons between these species show that there are differences in their Vitamin D pathways, but suggest that there are more factors contributing to these pathways than might be expected solely from life history characteristics. [ABSTRACT FROM AUTHOR]

We describe an efficient technology to obtain vitamin D 2 -enriched mushroom powder by exposing postharvest shiitake mushrooms (Lentinula edodes) to UV-B radiation. UV-B exposure took place in a self-designed semi-industrial facility with the required safety measures. The highest vitamin D 2 content (1000 IU g−1 DM) was found when a total UV-B dose of 24 kJ m−2 was distributed in two different moments of the process (75% on sliced fresh mushroom and the remaining 25% on the dry powder). Similar results were obtained in king oyster (Pleurotus eryngii) and Portobello button (Agaricus brunnescens) mushrooms, indicating that the developed technology could generally be used to produce vitamin D 2 supplements from mushrooms. In addition, the same method increased the vitamin D 2 content in shiitake by-products, which could be used for animal feed. The microbiological, toxicological, and nutritional quality of the enriched mushroom preparations were confirmed to ensure a safe consumption. To determine the vitamin D bioavailability in humans, the enriched shiitake powder was encapsulated using 600 mg per capsule, which was equivalent to the minimum daily intake of vitamin D for adults. The capsules were ineffective in improving serum 25-hydroxyvitamin D status, but prevented an excessive decrease in this parameter due to winter conditions. • Three mushrooms were irradiated with UV-B to increase their vitamin D 2 contents. • The highest increase was obtained with 24 kJ m−2 UV-B on both fresh and dry material. • A safe semi-industrial facility was designed to apply UV-B radiation. • Vitamin-enriched shiitake powder was encapsulated to study bioavailability in humans. • Shiitake capsules prevented an excessive decrease of serum 25-hydroxyvitamin D level. [ABSTRACT FROM AUTHOR]

Ultraviolet-B (UV-B) is an effective elicitor that enhances bioactive ingredient biosynthesis in different plants. Chrysanthemum morifolium Ramat (C. morifolium) is a well-known herbal medicine and beverage material, which is cultivated in many Asian countries and regions. The C. morifolium inflorescences are the main accumulation sites for active ingredients, which include flavonoids and chlorogenic acid. However, the molecular mechanisms underlying UV-B-mediated bioactive ingredient biosynthesis in C. morifolium inflorescences remain largely unknown. High-throughput sequencing technologies have been applied to identify the messenger RNAs (mRNAs) and microRNAs (miRNAs) responsive to UV-B radiation in C. morifolium inflorescences. Many UV-B responsive genes are enriched in flavonoid, unsaturated fatty acid, phenylpropanoid, and carotenoid biosynthesis pathways. In this study, we identified 169 miRNAs belonging to 38 typical families were detected in our constructed libraries. In total, 1954 unigenes were predicted to be targets of 118 miRNAs. Six miRNAs, PC-5p-7136_1319 , PC-3p-78379_156 , ath-MIR414-p5_2ss2CT21AC , PC-3p-154888_69 , nta-miR171a_2ss8GT18GA and htu-miR403a were involved in the regulation of active ingredient biosynthesis by targeting 4CL-like 5/9 , CYP81E8 , UGT91D1 and UGT72B1 genes. Five miRNAs, PC-5p-79_56613 , ath-miR858a_L-1 , ath-MIR414-p5_2ss15AC18AT , ath-MIR414-p5_2ss2CT21AC , and aly-miR393a-5p were involved in regulation of flavonoid biosynthesis by targeting MYB-bHLH complex-related transcription factor genes. Our data provides a platform for identifying mRNAs and miRNAs involved in the UV-B-induced accumulation of bioactive ingredients in C. morifolium inflorescences. • In C. morifolium inflorescences, 169 miRNAs belonging to 38 typic families were detected in all libraries. • A total of 1954 unigenes were predicted to be the targets of 118 miRNAs. • Six miRNAs were involved in the regulation of active ingredient biosynthesis. • Data reveals the function of UV-B in bioactive ingredient biosynthesis of the Chrysanthemum species. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the protective effect of Diospyros lotus leaf extract (DLE) on UVB-induced skin damage in mice. UVB irradiation of mice skin incurred significant damage to mice skin; increased thiobarbituric acid-reactive substance level; decreased superoxide dismutase; and glutathione levels in mice skin tissues. More so, UVB irradiation led to collagen degradation and infiltration of mast cell and neutrophils into mice skin leading to inflammation. However, topical application of DLE significantly reversed these conditions with the result comparable to l-ascorbic acid. Myricitrin, gallic acid, astragalin, myricetin-3- O -glactosside, and myricetin through high-performance liquid chromatography analysis were further determined to be the primary active compounds in DLE. In conclusion, our study showed that DLE has potentials as local therapeutic materials against skin damage by inhibiting oxidative stress and UVB-induced skin damage. [ABSTRACT FROM AUTHOR]

Humic substances have a tendency to form complexes with metal ions in aquatic medium, impacting the metal mobility, decreasing bioavailability and toxicity. Ultraviolet-B (UV-B) radiation exposure degrades the humic substance, changes their molecular weight distribution and their metal binding capacity in aquatic medium. In this study, we experimented the effect of UV-B radiation on the uranium complexed with fulvic acids and humic acids in a soft water system at different pH, uranium concentrations and radiant exposure. The concentration and distribution of uranium in a complexed form were investigated by asymmetrical flow field-flow fractionation coupled to multi detection technique (AsFlFFF-UV-ICP-MS). The major concentration of uranium present in complexes was primarily associated with average and higher molecular weight fulvic and humic acids components. The concentration of uranium in a complexed form increased with increasing fulvic and humic acid concentrations as well as pH of the solution. The higher molecular weight fraction of uranium was degraded due to the UV-B exposure, transforming about 50% of the uranium-dissolved organic carbon complexes into low molecular weight uranium species in complex form with organic ligands and/or free form. The result also suggests AsFlFFF-UV-ICP-MS to be an important separation and detection technique for understanding the interaction of radionuclides with dissolved organic matter, tracking size distribution changes during degradation of organic complexes for understanding mobility, bioavailability and ecosystem transfer of radionuclides as well as metals. [ABSTRACT FROM AUTHOR]

Glycyrrhizic acid ( GA), a natural triterpene, has received attention as an agent that has protective effects against chronic diseases including ultraviolet UV-B-induced skin photodamage. However, the mechanism of its protective effect remains elusive. Here, we used an immortalized human keratinocyte cell line (HaCaT) and a small animal model ( BALB/c mice), to investigate the protective effects of GA against UV-B-induced oxidative damage, and additionally, delineated the molecular mechanisms involved in the UV-B-mediated inflammatory and apoptotic response. In the HaCaT cells, GA inhibited the UV-B-mediated increase in intracellular reactive oxygen species ( ROS) and down-regulated the release of pro-inflammatory cytokines interleukin ( IL)-1 α, -1 β and -6, tumor necrosis factor ( TNF)- α and prostaglandin E2 ( PGE2). GA inhibited UV-B-mediated activation of p38 and JNK MAP kinases, COX-2 expression and nuclear translocation of NF- κB. Furthermore, GA inhibited UV-B-mediated apoptosis by attenuating translocation of Bax from the cytosol to mitochondria, thus preserving mitochondrial integrity. GA-treated HaCaT cells also exhibited elevated antiapoptotic Bcl-2 protein, concomitant with reduced caspase-3 cleavage and decreased PARP-1 protein. In BALB/c mice, topical application of GA on dorsal skin exposed to UV-B irradiation protected against epidermal hyperplasia, lymphocyte infiltration and expression of several inflammatory proteins, p38, JNK, COX-2, NF- κB and ICAM-1. Based on the above findings, we conclude that GA protects against UV-B-mediated photodamage by inhibiting the signalling cascades triggered by oxidative stress, including MAPK/ NF- κB activation, as well as apoptosis. Thus, GA has strong potential to be used as a therapeutic/cosmeceutical agent against photodamage. [ABSTRACT FROM AUTHOR]

We present the first multiyear set of simultaneous measurements of the global ultraviolet-B radiation and its two components: direct and diffuse. The measurements have been taken with four YES-UVB-1 radiometers: two radiometers to measure the diffuse radiation, one provided with a shadow band and the other with a shadow disk on a Sun tracker; a radiometer to measure the global horizontal radiation; and a Sun-tracking radiometer to measure the direct radiation with an especially designed radiance collimator. The diffuse minute-values measured with both instruments agree within a coefficient correlation of 1.00. The diffuse component represents at least 50% of the global UVB (ultraviolet-B) radiation. The minute values of global UVB irradiance obtained by adding the direct and diffuse components concur with the measured global irradiance. Therefore, the measurement of the direct irradiance enables the estimation of the diffuse component, and gives an insight into the factors that affect its value, especially aerosols. [ABSTRACT FROM AUTHOR]

The effect of the UV-B radiation on the latent fungi infection in strawberry fruit, on plant production and on physico-chemical quality parameters of strawberry fruits during postharvest preservation was investigated. The experiments were conducted under field conditions in two seasons during 2012. The different UV-B treatments were: Ambient solar UV-B; Ambient solar UV-B reduced by 80% [UV-B(−)] and Ambient solar UV-B supplemented with UV-B lamps [UV-B(+)]. An electronic modulation system was used to keep the increase on UV-B rate at constant levels throughout the day. The parameters evaluated were latent infection of fungi, dry matter of plants, physico-chemical attributes, color of the peel and fruit production. There was no significant difference among the irradiation treatments regarding the incidence of Rhizopus nigricans and Botrytis cinerea at both seasons. Independently on the season and the irradiation treatment, the incidence of R. nigricans was higher than the B. cinerea and this was considered the main postharvest fungi in the experiment. The incidence of Colletotrichum acutatum was limited to second season and it was higher on UV-B(+) treatment. The irradiation treatments had no influence on the dry matter, fruit production, the physico-chemical parameters and color. A strong correlation of both average temperature and precipitation on the incidence of R. nigricans and B. cinerea three weeks before harvesting was detected on both seasons using the Pearson correlation coefficients. The incidence of R. nigricans was positively correlated with precipitation and negatively correlated with average temperature. The inverse has been observed for B. cinerea . The results indicate that, on environmental conditions of a higher UV-B radiation, the probability of spoilage of strawberry fruit would be increased only by C . acutatum incidence. [ABSTRACT FROM AUTHOR]

The effects of ultraviolet-B (UV-B; 280-315 nm) radiation on certain key physiological and biochemical processes were studied in two Nostoc species harbouring diverse habitats. Nostoc sp. strain HKAR-2, a thermophilic cyanobacterium, was isolated from the hot-spring, Rajgir, whereas, Nostoc sp. HKAR-6 was a rice-field isolate from Banaras Hindu University, Varanasi. Complete killing of the cells occurred after 48 h of UV-B exposure in Nostoc sp. strain HKAR-6, whereas in case of Nostoc sp. strain HKAR-2 death occurred only after 72 h. Chlorophyll a and phycocyanin content were found to be adversely affected by UV-B irradiation in both the test organisms. However, a progressive increase in carotenoids content was observed upto 10 h of UV-B exposure but subsequently declined after 12 h in both the Nostoc sp. The antioxidative enzymes such as superoxide dismutase, catalase, ascorbate peroxidase and peroxidase that scavenge the UV-B generated harmful reactive oxygen species were found to have multifold induction in their content in both the strains following UV-B exposure in comparison to non-irradiated control cultures. In addition, these organisms also synthesize mycosporine-like amino acids (MAAs); able to carry out UV-screening. Porphyra-334 and shinorine were found to be the common MAAs in both the Nostoc sp., while an unknown MAAs with a retention time of 6.9 min (λ-334 nm) was found in Nostoc sp. strain HKAR-2. Findings from this study suggest that both enzymatic and non-enzymatic defense mechanisms are being employed by Nostoc sp. strain HKAR-2 and Nostoc sp. strain HKAR-6 to counteract the damaging effects of UV-B radiation. [ABSTRACT FROM AUTHOR]

Reductions in stratospheric ozone have resulted in increased levels of ultraviolet-B (UV-B, 280-315 nm) radiation reaching the earth's surface. UV-B radiation can damage plant DNA and photosynthetic machinery. Therefore, enhanced UV-B levels would seriously affect crop production in several regions of the world. Here, we provide a comprehensive report of intraspecific variability in the response of soybean to UV-B radiation and the genetic variation underlying UV-B resistance. We evaluated 140 genotypes, including 94 Glycine max and 46 G. soja accessions, for their sensitivity to supplemental UV-B radiation. Differences in responses to elevated UV-B levels, such as changes in leaf area and aerial biomass, were observed among soybean genotypes, supporting the notion that there is intraspecific variability in this response in G. soja as well as G. max. To explore how genetic variation contributes to differences in UV-B resistance, we sequenced the most UV-B resistant (IT162669) and sensitive (Cheongjakong 3) genotypes at the whole-genome level. Based on their homology and functional annotation, 137 genes were determined to be 'UV-B-related genes' in soybean, harboring almost 100 high-confidence single nucleotide polymorphisms between the two genotypes. Interestingly, we identified four genes with non-synonymous mutations that are related to plant protection mechanisms, such as the UV-protection, DNA damage repair and DNA damage tolerance pathways. Our results provide valuable information about UV-B-resistant soybean genotypes, UV-B-related soybean genes, and sequence variations between resistant and sensitive genotypes. [ABSTRACT FROM AUTHOR]

An experiment was conducted to evaluate the effects of UV-B radiation on immunity and carcass characteristics in quail. Three hundred Korean quail at 3 d old were weighed and randomly allocated into 5 groups (i.e., 30 males and 30 females per group), including 1 control group and 4 experiment groups (UV-1, UV-2, UV-3, and UV-4). Quail were subjected to UV-B irradiation with different doses: 0 µW/cm2 (control), 1.4 µW/cm2 (UV-1), 2.8 µW/cm2 (UV-2), 5.6 (UV-3), and 8.4 µW/cm2 (UV-4) each day. At 38 d of age, 15 males and 15 females in each group were randomly selected to measure immune index concentrations and carcass characteristics. The mean serum IgG, IgA, and alexin C4 concentrations of UV-1 quail were significantly improved, whereas UV-3 and UV-4 quail had better live weight and carcass characteristics. Taking into account immunity and carcass characteristics together, we conclude that the optimum dose of UV radiation for Korean quail is 1.4 µW/cm2 each day. Moreover, female quail had better carcass characteristics than males in most indices of carcass characteristics. [ABSTRACT FROM PUBLISHER]

Precise allocation of limited resources between growth and defense is critical for plant survival. In shade-intolerant species, perception of competition signals by informational photoreceptors activates shade-avoidance responses and reduces the expression of defenses against pathogens and insects. The main mechanism underlying defense suppression is the simultaneous downregulation of jasmonate and salicylic acid signaling by low ratios of red:far-red radiation. Inactivation of phytochrome B by low red:far-red ratios appears to suppress jasmonate responses by altering the balance between DELLA and JASMONATE ZIM DOMAIN (JAZ) proteins in favor of the latter. Solar UVB radiation is a positive modulator of plant defense, signaling through jasmonate-dependent and jasmonate-independent pathways. Light, perceived by phytochrome B and presumably other photoreceptors, helps plants concentrate their defensive arsenals in photosynthetically valuable leaves. The discovery of connections between photoreceptors and defense signaling is revealing novel mechanisms that control key resource allocation decisions in plant canopies. [ABSTRACT FROM AUTHOR]

Abstract: Effects of contaminants on behavior may have important consequences on wildlife populations because behaviors such as predation, predator avoidance, reproduction, and social interaction can affect population dynamics. As a common environmental stressor, ultraviolet-B (UVB) radiation causes various deleterious effects and some aquatic organisms actively avoid UVB radiation in water. However, the extent to which environmental contaminants can impair UVB avoidance has not been evaluated, which may cause greater UVB exposure and toxicity. In the present study, we used Xenopus laevis tadpoles to determine if acute exposure to sublethal concentrations of agricultural chemicals can alter tadpole response to UVB radiation. We exposed tadpoles to four pesticides (malathion, endosulfan, α-cypermethrin, and chlorothalonil) for 96h. At the end of the exposure, tadpoles were transferred to tanks divided into UVB and no-UVB areas. We observed tadpoles for 30min and recorded time spent in the UVB area. We compared the proportion of time tadpoles spent in the UVB area among different concentrations for each pesticide. There was no significant difference between FETAX control and solvent control tadpoles. When combined, control tadpoles spent less than half of the time in the UVB area indicating that X. laevis tadpoles exhibit UVB avoidance behavior. Tadpoles exposed to 5μg/L endosulfan spent significantly more time under UVB than control tadpoles. Other pesticides had no effect on tadpole UVB avoidance behavior. Our results suggest that some neurotoxic pesticides can affect UVB avoidance in larval amphibians, which may increase their exposure and subsequently the risk of UVB-induced damage. The present study highlights the importance of examining the interaction between two stressors that co-occur across broad spatial scales and to consider behavioral alteration when evaluating the risk of pesticides to amphibians. [Copyright &y& Elsevier]

The aim of this study was to investigate the effect of silicon (Si) on soybean seedlings under (combined) drought and ultraviolet-B (UV-B) radiation stresses. Specifically, we determined dry matter accumulation and partitioning of the mineral elements in different organs of soybean seedlings using the inductively coupled plasma mass spectrometry (ICP-MS). The amount of dry matter accumulated in root, stem, and leaf of seedlings treated with (combined) drought and UV-B radiation stresses were lower than that of the control. Also, the content of macroelements in seedlings under the combined stress was lower than in those under control conditions. Changes in the contents of microelements varied according to the intensity of drought, UV-B radiation, and the organs of soybean. The relationship between the contents of mineral elements and the accumulation of dry matter also varied similarly. These results demonstrated that drought and UV-B radiation induced an alteration in the distribution of mineral elements in root, stem and leaf, leading to decreases in dry matter accumulation and inhibition of soybean growth. [ABSTRACT FROM PUBLISHER]

The aim of this study was to investigate the potential of silicon (Si) for alleviating Ultraviolet-B (UV-B) radiation stress based on changes in biomass, physiological attributes and photosynthetic characteristics of two soybean (Glycine maxL.) cultivars, Kenjiandou 43 (‘K 43’) and Zhonghuang 35 (‘ZH 35’). The cultivars were raised with and without Si in the greenhouse, and then subjected to ambient, ambient + 2.7 kJ m−2d−1and ambient + 5.4 kJ m−2d−1of UV-B radiation. Depending on cultivar, plants suffered severe growth limitations under UV-B radiation, but the application of Si alleviated the adverse effects on growth and development by increasing the stem length, net photosynthetic rate (PN) and leaf chlorophyll content. Concurrently, it decreased the stomatal conductance (Sc) and intercellular carbon dioxide (CO2) concentration (Ci). In response to the UV-B radiation stress, the antioxidant enzyme activities of superoxide dismutase (SOD) increased by 41.2–72.7%, peroxidases (POD) by 49.5–85.7%, malodialdehyde (MDA) by 6.7–20.4% and soluble protein by 4.2–7.6%. The overall results indicated that media treatment with Si might improve soybean growth under elevated UV-B radiation through positive changes in biomass and some physiological attributes that were dependent on cultivar. [ABSTRACT FROM PUBLISHER]

In vivo chlorophyll fluorescence analysis reflecting the photosystem II functionality was investigated in the cyanobacterium Anabaena variabilis PCC 7937 under simulated solar radiation in a combination with various cut-off filters (WG 280, WG 295, WG 305, WG 320, WG 335, WG 345, and GG 400) to assess the effects of photosynthetically active radiation (PAR), ultraviolet-A (UV-A), and ultraviolet-B (UV-B) radiations on photosynthesis. The photosynthetic activity (PA) was severely inhibited immediately after 10 min of exposure to high PAR, UV-A, and UV-B radiations compared with low PAR grown control samples. After 1 h of exposure, PA of 17.5 ± 2.9% was detected in the high PAR exposed samples compared with the control, while only a trace or no PA was observed in the presence of ultraviolet radiation (UVR). A recovery of PA was recorded after 2 h of the exposure, which continued for next 4, 8, 12, and 24 h. After 24 h of the exposure, PA of 57.5 ± 1.9%, 36.1 ± 11.7%, 23.5 ± 3.3%, 22.3 ± 5.2%, 20.8 ± 6.7%, 13.2 ± 6.6%, and 21.6 ± 9.5% was observed compared with the control sample in 400, 345, 335, 320, 305, 295, and 280 nm cut-off filters-covered samples, respectively. The relative electron transport rate, measured after 24 h exposure, showed also a disturbance in electron transfer between the two photosystems under the high PAR and UVR treatments relative to the control samples, suggesting the inhibition of photosynthesis. This study suggests that both high PAR and UVR inhibited the photosynthetic performance of A. variabilis PCC 7937 by damaging the photosynthetic apparatus, however, photoprotective mechanisms evolved by the organism allowed an immediate repair of ecologically important machinery, and enabled its survival. [ABSTRACT FROM AUTHOR]

Chlorophyll (Chl) a fluorescence parameters and rapid light curves of soybean [ Glycine max (L.) Merrill] were measured by pulse amplitude modulation fluorometry. Measurements were taken during different stages of soybean growth under field conditions with 20% enhancement in ultraviolet-B (UV-B) radiation. Results showed that supplemental UV-B radiation decreased Chl contents by 5.5% ( P=0.048), 8.7% ( P=0.046), and 10.5% ( P=0.005) in seedling, in branching-flowering, and in pod-setting stages, respectively. In the branching-flowering and pod-setting stages, maximum quantum yield of photosystem (PS) II photochemistry (F/F) decreased by 6.1% ( P=0.001) and 3.0% ( P=0.009), respectively. Supplemental UV-B radiation significantly decreased the effective quantum yield ( Y). The photosynthetic capacity at light saturation (P) also decreased in both the seedling and branching-flowering stages by 28.9% ( P=0.007) and 15.5% ( P=0.041), respectively. However, Y and Pm showed no significant difference in the trefoil and pod-setting stages with and without the UV treatment. The light saturation parameter ( E) decreased by 21.1% ( P=0.000) and 23.2% ( P=0.029) in the trefoil and seedling stages, respectively. Moreover, the initial slope ( α) decreased by 21.1% ( P=0.001) in the branching-flowering stage. Nonphotochemical quenching (NPQ) in the seedling stage and photochemical quenching coefficient (q) in the branching-flowering stage decreased significantly under UV-B treatments. The results of the present study suggest that supplemental UV-B radiation adversely affected Chl content and electron transport activity in PSII and consequently decreased the photosynthetic efficiency of soybean plants. [ABSTRACT FROM AUTHOR]

Ultraviolet-B (UV-B) radiation constitutes a minor part of the solar spectrum, being most of this solar radiation absorbed by the UV-screening stratospheric ozone layer. Yet, a global depletion of the ozone layer, largely due to the release of chlorofluorocarbons caused by human activities, has resulted in an increase of solar UV-B radiation at the earth's surface. Accordingly, in the temperate latitudes, such ozone decrease reached ca. 3% and 6% in the North and South hemispheres, respectively, between 2002 and 2005 (as compared to the 1970s). Despite the uncertainty of long-term predictions, it is also estimated an UV-B increase of 5-10% over temperate latitudes within the next 15 years In this context, this work aim at to present an overview of plants sensitivity/tolerance to UV-B irradiation mostly considering the key photosynthetic metabolism. [ABSTRACT FROM AUTHOR]

Abstract: As one of the important problems in global change, elevated ultraviolet-B (UV-B) radiation induced by the depletion of stratospheric ozone layer has received more and more attentions around the world. Field experiment was conducted to investigate 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, 14.4kJm−2 d−1, 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 significantly decreased tiller number and the biomass of straw and root in rice. 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 emission in the paddy soil. CH4 emission was higher in parent rice than transgenic rice. It is suggested that planting herbicide resistant transgenic rice will be helpful in mitigating CH4 emission from paddy fields under elevated UV-B radiation. [Copyright &y& Elsevier]

The effects of elevated ultraviolet-B (UV-B) radiation on methane dynamics was studied in a natural fen in Northern Finland for three growing seasons (2003-2005). This is the first in situ study on the effects of elevated UV-B radiation on methane dynamics in a natural fen. The experimental setup consisted of 30 study plots (120 × 120 cm) that were randomly divided into three treatments: ambient control, UV-A control and elevated UV-B. The UV-B enhancements were 63, 37 and 21% above ambient during the growing seasons 2003, 2004 and 2005, respectively. Elevated UV-B did not affect net methane emission. Stable isotope composition of methane indicated that methane was produced by the acetate fermentation. Under elevated UV-B there was a slight increase in the concentrations of acetate and propionate but decrease in the oxalate concentration suggesting UV-B-induced changes in the belowground processes. The results emphasize the need for long-term field studies under moderately enhanced exposures to estimate whether the function and feedbacks of mire ecosystems change under increased UV-B radiation. [ABSTRACT FROM AUTHOR]

The effects of elevated UV-B radiation and two nitrogen (N) sources on mineral nutrition of Cyclopia maculata, a UV-B-sensitive species, was assessed together with UV-B-tolerant symbiotic legumes Vigna unguiculata, Glycine max, Lupinus luteus, Vicia atropurpurea, Podalyria calyptrata and Virgilia oroboides. Plants were grown outdoors on tables under moderately or highly elevated UV-B exposures which simulated 15% and 25% ozone depletion above Cape Town in South Africa. Exposing purely symbiotic plants of  V. unguiculata to elevated UV-B132 radiation decreased the tissue concentration of calcium (Ca) in leaves, phosphorus (P) in stems and roots, potassium (K) in roots, and boron (B) in roots and nodules relative to UV-B162 or ambient control. In contrast, seedlings of C. maculata, V. oroboides, L. luteus, and V. atropurpurea plants exposed to elevated UV-B radiation increased the concentration of several nutrients in leaves, stems and roots whereas P. calyptrata showed no changes in the mineral nutrition. The reported reduction in plant dry matter yield in C. maculata was accompanied with increased concentrations of P, K, Ca, magnesium (Mg), copper (Cu), and manganese (Mn) in photosynthetic leaves and stems, suggesting that the reported decrease in biomass yield could not be attributed to limitations associated with nutrient uptake. Our results suggest that factors other than limitations of nutrient uptake contributed to the reduced biomass accumulation of purely symbiotic and nitrate (NO3 −)-fed nodulated seedlings of C. maculata. [ABSTRACT FROM PUBLISHER]

Several studies have found the photosynthetic integration in clonal plants to response to resource heterogeneity, while little is known how it responses to heterogeneity of UV-B radiation. In this study, the effects of heterogeneous UV-B radiation (280-315 nm) on gas exchange and chlorophyll fluorescence of a clonal plant Trifolium repens were evaluated. Pairs of connected and severed ramets of the stoloniferous herb T. repens were grown under the homogeneity (both of ramets received only natural background radiation, ca. 0.6 kJ m d) and heterogeneity of UV-B radiation (one of the ramet received only natural background radiation and the other was exposed to supplemental UV-B radiation, 2.54 kJ m d) for seven days. Stomatal conductance ( g), intercellular CO concentration ( C) and transpiration rate ( E) showed no significant differences in connected and severed ramets under homogenous and heterogeneous UV-B radiation, however, net photosynthetic rate ( P) and maximum photosynthetic rate ( P) of ramets suffered from supplemental increased UV-B radiation and that of its connected sister ramet decreased significantly. Moreover, additive UV-B radiation resulted in a notable decrease of the minimal fluorescence of dark-adapted state (F), the electron transport rate (ETR) and photochemical quenching coefficient (q) and an increase of nonphotochemical quenching (NPQ) under supplemental UV-B radiation, while physiological connection reverse the results. In all, UV-B stressed ramets could benefit from unstressed ramets by physiological integration in photosynthetic efficiency, and clonal plants are able to optimize the efficiency to maintain their presence in less favourable sites. [ABSTRACT FROM AUTHOR]

Abstract: Previously we have selected wild sugarcane (Saccharum spontaneum L.) sterile lines that are tolerant or susceptible to UV-B radiation based on response index (RI) in a field screening test. The RI was established according to plant height, tiller number, leaf index, total biomass and brix under enhanced ultraviolet-B (UV-B, 280–310nm) radiation. In this experiment, molecular markers linked to the UV-B tolerant and susceptible genes were identified and cloned. RAPD (Randomly amplified polymorphic DNAs) assay using 100 arbitrary primers followed by clustering analysis separated the tolerant and susceptible lines into two groups at the genetic distance of 0.380. The UV-B tolerant and susceptible gene pools were constructed and compared using the Bulked Segregate Analysis (BSA) approach. Of the 100 arbitrary RAPD primers, primer OPR16 produced polymorphic DNA banding patterns from both gene pools. The OPR16-1200bp DNA fragment was only amplified from the tolerant lines and the OPR16-800bp from the susceptible ones. These two PCR fragments were cloned onto T-vector. DNA sequence alignment analysis determined that 42% homology existed between the reverse and forward sequences of the OPR16-1200bp clone, and 36% homology between the forward sequences of the OPR16-800bp and OPR16-1200bp clones. The two DNA clones were determined to be linked to the UV-B tolerant and susceptible genes, and they can be used to develop molecular markers for the associated traits. [Copyright &y& Elsevier]

Increased ultraviolet-B (UV-B) radiation as a consequence of ozone depletion is one of the many potential drivers of ongoing global amphibian declines. Both alone and in combination with other environmental stressors, UV-B is known to have detrimental effects on the early life stages of amphibians, but our understanding of the fitness consequences of these effects remains superficial. We examined the independent and interactive effects of UV-B and predatory chemical cues (PCC) on a suite of traits of Limnodynastes peronii embryos and tadpoles, and assessed tadpole survival time in a predator environment to evaluate the potential fitness consequences. Exposure to a 3 to 6 per cent increase in UV-B, which is comparable to changes in terrestrial UV-B associated with ozone depletion, had no effect on any of the traits measured, except survival time in a predator environment, which was reduced by 22 to 28 per cent. Exposure to PCC caused tadpoles to hatch earlier, have reduced hatching success, have improved locomotor performance and survive for longer in a predator environment, but had no effect on tadpole survival, behaviour or morphology. Simultaneous exposure to UV-B and PCC resulted in no interactive effects. These findings demonstrate that increased UV-B has the potential to reduce tadpole fitness, while exposure to PCCs improves their fitness. [ABSTRACT FROM AUTHOR]

Abstract: Physiological integration has been documented in many clonal plants growing under resource heterogeneity. Little is still known about the response of physiological integration to heterogeneous ultraviolet-B radiation. In this paper, the changes in intensity of physiological integration and of physiological parameters under homogeneous and heterogeneous ultraviolet-B radiation (280–315nm) were measured in order to test the hypothesis that in addition to resource integration a defensive integration in Trifolium repens might exist as well. For this purpose, homogeneous and heterogeneous ultraviolet-B radiation was applied to pairs of connected and severed ramets of the stoloniferous herb Trifolium repens. Changes in intensity of water and nutrient integration were followed with acid fuchsin dye and 15N-isotope labeling of the xylem water transport. In order to assess the patterns of physiological integration contents of chlorophyll, ultraviolet-B absorbing compounds, soluble sugar and protein were determined and activities of superoxide dismutase (SOD) and peroxidase (POD) measured. When ramets were connected and exposed to heterogeneous UV-B radiation, the velocity of water transportation from the UV-B treated ramet to its connected sister ramet was markedly lower and the percentage of 15N left in labelled ramets that suffered from enhanced UV-B radiation was higher and their transfer to unlabelled ramets lower. In comparison with clones under homogeneous ultraviolet-B radiation, the content of chlorophyll, ultraviolet-B absorbing compounds, soluble sugar and activities of SOD and POD increased notably if ultraviolet-B stressed ramets were connected to untreated ramets. Chlorophyll and UV-B absorbing compounds were shared between connected ramets under heterogeneous UV-B radiation. This indicated that physiological connection improved the performance of whole clonal plants under heterogeneous ultraviolet-B radiation. The intensity of physiological integration of T. repens for resources decreased under heterogeneous ultraviolet-B radiation in favor of the stressed ramets. Ultraviolet-B stressed ramets benefited from unstressed ramets by physiological integration, supporting the hypothesis that clonal plants are able to optimize the efficiency of their resistance maintaining their presence also in less favorable sites. The results could be helpful for further understanding of the function of heterogeneous UV-B radiation on growth regulation and microevolution in clonal plants. [Copyright &y& Elsevier]

1. Environmental stressors have both lethal and sublethal effects, such as altered developmental rates and the induction of malformations. Ecological interactions, including predation and competition, often amplify such effects, for instance by inducing behavioural changes that increase susceptibility to the stress. 2. Using experimental mesocosms, we asked whether the density of conspecific competitors and predation risk from larval water beetles ( Dytiscus spp.) affect the development of malformations in tadpoles of the wood frog ( Rana sylvatica). We also examined whether such malformities increase the susceptibility of tadpoles to predation. 3. The risk of predation decreased the frequency of malformities in both low- and high-density treatments, although this effect was greater at low density. Behavioural observations suggested that reductions in activity by amphibian larvae induced by predators mediated these responses by decreasing cumulative exposure to ultraviolet-B radiation, the putative stressor causing the observed malformity. These results suggest that predators can reduce negative impacts of stressors by inducing behavioural changes in prey organisms. 4. Malformed individuals were twice as vulnerable to predators as non-malformed individuals, suggesting that sublethal effects can ultimately cause increased mortality. [ABSTRACT FROM AUTHOR]

Abstract: Aboveground litter decomposition is controlled mainly by substrate quality and climate factors across terrestrial ecosystems, but photodegradation from exposure to high-intensity ultraviolet-B (UVB) radiation may also be important in arid and semi-arid environments. We investigated the interactive effects of UVB exposure and litter quality on decomposition in a Tamarix-invaded riparian ecosystem during the establishment of an insect biological control agent in northern Nevada. Feeding by the northern tamarisk beetle (Diorhabda carinulata) on Tamarix spp. trees leads to altered leaf litter quality and increased exposure to solar UVB radiation from canopy opening. In addition, we examined the dynamics of litter decomposition of the invasive exotic Lepidium latifolium, because it is well-situated to invade beetle-infested Tamarix sites. Three leaf litter types (natural Tamarix, beetle-affected Tamarix, and L. latifolium) differing in substrate quality were decomposed in litterbags for one year in the field. Litterbags were subjected to one of three treatments: (1) Ambient UVB or (2) Reduced UVB (where UVB was manipulated by using clear plastic films that transmit or block UVB), and (3) No Cover (a control used to test for the effect of using the plastic films, i.e. a cover effect). Results showed a large cover effect on rates of decomposition and nutrient release, and our findings suggested that frequent cycles of freeze–thaw, and possibly rainfall intensity, influenced decomposition at this site. Contrary to our expectations, greater UVB exposure did not result in faster rates of decomposition. Greater UVB exposure resulted in decreased rates of decomposition and P release for the lower quality litter and no change in rates of decomposition and nutrient release for the two higher quality litter types, possibly due to a negative effect of UVB on soil microbes. Among litter types, rates of decomposition and net release of N and P followed this ranking: L. latifolium > beetle-affected Tamarix > natural Tamarix. Altered nutrient dynamics with beetle introduction as well as the rapid decomposition rates exhibited by L. latifolium are consistent with vulnerability to secondary invasion. In this desert ecosystem, decomposition and nutrient release were strongly affected by litter type and much less so by UVB exposure. [Copyright &y& Elsevier]

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. [ABSTRACT FROM PUBLISHER]

Elevated carbon dioxide (CO2), temperature (T) and ultraviolet-B (UV-B) radiation may affect plant growth and secondary chemistry in different directions, but the effect of the combination of the three factors has seldom been tested. Here, we grew four dark-leaved willow (Salix myrsinifolia) clones under combinations of ambient or elevated CO2, T and UV-B radiation in top-closed chambers for 7 wk. Elevated UV-B had no effects on growth or phenolic compounds, and there were no significant interactions between UV-B, CO2 and T. CO2 alone increased most growth parameters, but the magnitude of the effect varied among the clones. Total phenolics increased at elevated CO2, whereas they decreased at elevated T. The responses varied between the clones. The results imply that dark-leaved willow are fairly resistant to the applied three-factor climate change, probably because of high constitutive defense. However, the interactions between clone and climate change factors implies that some clones are more susceptible than the species as a whole. [ABSTRACT FROM AUTHOR]

Abstract: Ultraviolet-B radiation regulates plant growth and morphology at low and ambient fluence rates but can severely impact on plants at higher doses. Some plant UV-B responses are related to the formation of reactive oxygen species (ROS) and pyridoxine (vitamin B6) has been reported to be a quencher of ROS. UV-B irradiation of Arabidopsis Col-0 plants resulted in increased levels of PDX1 protein, compared with UV-A-exposed plants. This was shown by immunoblot analysis using specific polyclonal antibodies raised against the recombinant PDX1.3 protein and confirmed by mass spectrometry analysis of immunoprecipitated PDX1. The protein was located mainly in the cytosol but also to a small extent in the membrane fraction of plant leaves. Immunohistochemical analysis performed in pea revealed that PDX1 is present in UV-B-exposed leaf mesophyll and palisade parenchyma but not in epidermal cells. Pyridoxine production increased in Col-0 plants exposed to 3 days of UV-B, whereas in an Arabidopsis pdx1.3 mutant UV-B did not induce pyridoxine biosynthesis. In gene expression studies performed after UV-B exposure, the pdx1.3 mutant showed elevated transcript levels for the LHCB1∗3 gene (encoding a chlorophyll a/b-binding protein of the photosystem II light-harvesting antenna complex) and the pathogenesis-related protein 5 (PR-5) gene, compared with wild type. [Copyright &y& Elsevier]

Abstract: The impact of climatic change on crop production is a major global concern. One of the climatic factors, ultraviolet-B radiation (UV-B; 280–320nm), which is increasing as a result of depletion of the global stratospheric ozone layer, can alter crop productivity. As the initial step in development of UV-B tolerant rice cultivars for the southern U.S., in this study we screened popular southern U.S. rice cultivars for variation in tolerance to elevated UV-B radiation with respect to morphological, phenological and physiological parameters. Plants grown in the greenhouse at the Texas AgriLife Research and Extension Center in Beaumont, Texas, U.S. were exposed to 0, 8 or 16kJm−2 day−1 UV-B radiation for 90 days. Our results showed differences among southern US rice cultivars in response to UV-B treatments with respect to leaf photosynthetic rate (Pn), leaf phenolic concentration, pollen germination (PG), spikelet fertility (SF), leaf number, leaf area, and yield. For most of the cultivars, plants exposed to enhanced UV-B radiation showed decreased Pn, PG, SF and yield and increased spikelet abortion and leaf phenolic concentration compared to the plants grown in a UV-B-free environment. In this study, cultivar ‘Clearfield XL729’ performed better than the other cultivars under enhanced UV-B radiation. [ABSTRACT FROM AUTHOR]

Abstract: Silicon (Si) may be involved in metabolic, physiological, and/or structural activity in higher plants exposed to abiotic and biotic stresses. This has not yet been determined due to the absence of direct evidence that it is part of the molecule of an essential plant constituent or metabolite. The aim of this study was to investigate the effect of silicon on soybean seedlings under drought and ultraviolet-B (UV-B) radiation stresses. The relative leaf water content (RWC), which was the main factor resulting in reduced growth in response to drought, increased 19.0% and 30.0% with Si application under drought and drought+UV-B stresses, respectively. Under UV-B radiation, the anthocyanin and phenol levels decreased 91.5% and 10.0% in the treatment of Si. Ultraviolet-B radiation and drought stress caused great membrane damage, as assessed by lipid peroxidation and osmolyte leakage, but Si application significantly reduced the membrane damage. Catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and hydrogen peroxide were observed under stress conditions. Proline increased primarily in drought-stressed seedlings and may be the drought-induced factor with a protective role in response to UV-B and silicon. Photosynthesis (P N) increased following Si application by 21.0%, 18.3% and 21.5% under UV-B radiation, drought and the combination, respectively. The physiological and biochemical parameters measured indicated that the UV-B light had more adverse effects on growth of soybean seedlings than drought, but the data also showed that Si could alleviate seedling damage under these stress conditions. [ABSTRACT FROM AUTHOR]

Abstract: Genetic analyses of Gnaphalium’s DNA showed a high degree of polymorphism in UV-B irradiated plants when compared to controls. Among the five tested primers the four ISSR primers selected for this analysis generated a total of 189 fragments. A high proportion of polymorphic bands ranging from 70% to 28% were found using these ISSR markers. Nei and Li similarity indexes were used to evaluate genetic divergence among plants. The dendrograms obtained using these markers efficiently separate plants from different treatments. A linear relationship was observed between UV-B dose and percentage of dissimilarity which may be related to DNA damage caused by the different UV-B treatments. [ABSTRACT FROM AUTHOR]

Abstract: Heme oxygenase (HO) has antioxidant properties and is up-regulated by reactive oxygen species (ROS) in ultraviolet-B-irradiated soybean plants. This study shows that nitric oxide (NO) protects against oxidative damage and that nitric oxide synthase (NOS)-like activity is also required for HO-1 induction under UV-B radiation. Pre-treatments with sodium nitroprussiate (SNP), a NO-donor, prevented chlorophyll loss, H2O2 and accumulation, and ion leakage in UV-B-treated plants. HO activity was significantly enhanced by NO and showed a positive correlation with HO-1 transcript levels. In fact, HO-1 mRNA levels were increased 2.1-fold in 0.8mM SNP-treated plants, whereas subsequent UV-B irradiation augmented this expression up to 3.5-fold with respect to controls. This response was not observed using ferrocyanide, a SNP inactive analog, and was effectively blocked by 2-(4-carboxyphenil)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO), a specific NO-scavenger. In addition, experiments carried out in the presence of NG-nitro-l-arginine methyl ester (l-NAME) or tungsten, well-known inhibitors of NOS and nitrate reductase, showed that NOS is the endogenous source of NO that mediates HO-1 expression. In summary, we found that NO is involved in the signaling pathway leading to HO-1 up-regulation under UV-B, and that a balance between NO and ROS is important to trigger the antioxidant response against oxidative stress. [Copyright &y& Elsevier]

Enhanced ultraviolet-B (UV-B) radiation may have multiple effects on both plants and animals and affect plant–herbivore interactions directly and indirectly by inducing changes in host plant quality. In this study, we examined combined effects of UV-B and herbivory on the defence of the mountain birch ( Betula pubescens ssp. czerepanovii) and also the effects of enhanced UV-B radiation on a geometrid with an outbreak cycle: the autumnal moth ( Epirrita autumnata). We established an experiment mimicking ozone depletion of 30% (a relevant level when simulating ozone depletion above Northern Lapland). Both arctic species responded only slightly to the enhanced level of UV-B radiation, which may indicate that these species are already adapted to a broader range of UV-B radiation. UV-B exposure slightly induced the accumulation of myricetin glycosides but had no significant effect on the contents of quercetin or kaempferol derivatives. Mountain birch seedlings responded more efficiently to herbivory wounding than to enhanced UV-B exposure. Herbivory induced the activities of foliar oxidases that had earlier been shown to impair both feeding and growth of moth larvae. In contrast, the contents of foliar phenolics did not show the same response in different clones, except for a decrease in the contents of tannin precursors. The induction of foliar phenoloxidase activities is a specific defence response of mountain birches against insect herbivory. To conclude, our results do not support the hypothesis that the outbreak cycle of the autumnal moth can be explained by the cycles of solar activity and UV-B. [ABSTRACT FROM AUTHOR]

Relatively few studies have investigated plant responses to the combined effects of multiple environmental factors. We studied the responses of canola (Brassica napus) seedlings to combinations of temperatures (22°/18°C and 28°124°C), ultraviolet-B (UVB) radiation levels (S [ambient] and 10 [enhancedj kJ m-2 d-1), and watering regimes (well watered and water stressed). The higher temperature decreased stem diameter, leaf area, individual organ and total-plant dry mass (DM), net CO2 assimilation (AN), water use efficiency (WUE), the chlorophyll (Chi) a-Chl b ratio, and UV-absorbing compounds but increased specific leaf mass (SLM), leaf mass ratio (LMR), shoot-root ratio (SRR), and Chl b. Enhanced UVB reduced leaf number and area, DM accumulation, SLM, LMR, AN, WUE, carotenoids, and Chl a : Chl b but increased leaf area ratio, SRR, and ethylene evolution. Water stress decreased plant growth, leaf moisture, leaf, stem, and total DM, LMR, SRR, and gas exchange but increased photosynthetic pigments, UV-absorbing compounds, epicuticular wax, and ethylene evolution. Many plant parameters were affected by two- and three-way interactions. Main factors and their interactions revealed that water stress has a larger negative influence on plants than the other two factors. We suggest that, under conditions of global climate change, water stress may have a stronger effect on plant performance than UVB radiation. [ABSTRACT FROM AUTHOR]

Kappaphycus alvarezii is a seaweed of great economic importance for the extraction of kappa carrageenan from its cell walls. The most common strains are dark red, brown, yellow, and different gradations of green. It is known that ultraviolet radiation (UVR) affects macroalgae in many important ways, including reduced growth rate, reduction of primary productivity, and changes in cell biology and ultrastructure. Therefore, we examined the brown strain of K. alvarezii exposed to ultraviolet-B radiaton (UVBR) for 3 h per day during 28 days of cultivation. The control plants showed growth rates of 7.27% d−1, while plants exposed to UVBR grew only 4.0% d−1. Significant differences in growth rates and in phycobiliproteins between control and exposed plants were also found. Compared with control plants, phycobiliprotein contents were observed to decrease after UV-B exposure. Furthermore, the chlorophyll a (Chl a) contents decreased and showed significant differences. UVBR also caused changes in the ultrastructure of cortical and subcortical cells, which included increased thickness of the cell wall and number of plastoglobuli, reduced intracellular spaces, changes in the cell contour, and destruction of chloroplast internal organization. Reaction with Toluidine Blue showed an increase in the thickness of the cell wall, and Periodic Acid-Schiff stain showed a decrease in the number of starch grains. By the significant changes in growth rates, photosynthetic contents and ultrastructual changes observed, it is clear that UVBR negatively affects intertidal macroalgae and, by extension, their economic viability. [ABSTRACT FROM AUTHOR]

Amphibian declines are a prominent part of the global biodiversity crisis and have received special consideration because they have occurred relatively recently, on a global scale, and in seemingly pristine habitats where no obvious anthropogenic cause is apparent. Although several causes for declines have been implicated, the isolation of a singular cause has proven elusive. Consequently, it has been hypothesized that complex interactions between multiple environmental stressors, particularly those associated with global change, may be responsible. Increasing ultraviolet-B radiation (UV-B) associated with stratospheric ozone depletion is one such stressor that has received considerable attention. UV-B causes enhanced lethal effects when combined with other factors such as aquatic pH, contaminants, temperature and pathogens, but little is known of how UV-B interacts with pervasive biological stressors, such as risk of predation. We exposed Limnodynastes peronii tadpoles to UV-B and predatory chemical cues in a controlled laboratory experiment to determine their independent and interactive effects on survival and morphology. We show that UV-B and risk of predation interact synergistically to enhance mortality above the additive effects of the independent stressors, and that exposure to UV-B affects the ability of tadpoles to morphologically respond to predatory chemical cues (i.e. predator-induced phenotypic plasticity), which has implications for their survival in an environment with predators. This highlights the importance of considering both anthropogenic and naturally occurring stressors when examining the underlying causes of amphibian declines. [ABSTRACT FROM AUTHOR]

Due to anthropogenic influences, solar UV-B irradiance at the earth's surface is increasing. To determine effects of enhanced UV-B radiation on sweet almond (Prunus dulcis), one-year old seedlings were submitted to four levels of UV-B radiation namely 0 (UV-BC), 0.45 (UV-B1), 1 (UV-B2), 1.50 (UV-B3), and 1.96 (UV-B3) W m-2 at a PAR intensity of 300 μ mol m-2 s-1 for 5 weeks. UV-B stress led to a significant decrease (p<0.05 ) in photosynthetic and non-photosynthetic pigments such as chlorophyll a, chlorophyll b, total chlorophyll and carotenoid content, whereas a significant increase was observed for UV-B absorbing pigments (flavonoid and anthocyanin), total soluble sugars and relative electrolyte conductivity. Most of the studied parameters were only affected at high UV-B levels (> UV-B3). [ABSTRACT FROM AUTHOR]

Abstract: Enhanced ultraviolet-B (UVB) radiation and water deficit affect plant growth and development. We determined the effects of UVB and drought stress on growth parameters and chemical attributes of two ecotypes (alpine and prairie) of Stellaria longipes under controlled-environment conditions. Clonal ramets of these ecotypes were grown under three UVB levels (0, 5, and 10kJm−2 d−1) and exposed to two watering regimes (well watered and drought stressed) for 21 days. Compared to the alpine, the prairie ecotype was taller, had higher number of nodes, and greater leaf area and specific leaf weight (leaf dry weight: leaf area), which resulted in increased dry matter in this ecotype. Overall, ‘prairie’ was higher in total chlorophyll (Chl), but lower in Chla:b ratio, flavonoids, and ethylene, than ‘alpine’. In both ecotypes, UVB and drought stress reduced growth and dry matter, whereas UVB increased carotenoids and flavonoids. Drought stress decreased ethylene evolution. These characteristics were also determined in plants growing in the field. In the field-growing plants, ‘prairie’ had higher growth and dry matter, but lower Chla:b ratio and flavonoids, than ‘alpine’. The two ecotypes responded differentially to UVB and watering regime, as ‘prairie’ appeared to be more sensitive to UVB and drought stress than ‘alpine’. [Copyright &y& Elsevier]

Depletion of the stratospheric ozone layer is leading to an increase in ultraviolet-B (UVB) radiation (280–320 nm) reaching the Earth’s surface, which can alter crop productivity. The objective of this study was to determine the effects of elevated UVB radiation on rice production with special emphasis on grain characteristics in southern US rice cultivars (six inbred cultivars and three hybrids). Due to the spectral characteristics of the greenhouse glass, plants received no natural UVB radiation; hence, plants were provided with supplemental UVB lighting. Plants were exposed to UVB radiation of 0, 8 (ambient) or 16 (twice ambient) kJ m−2 day−1. There was no significant effect of elevated UVB radiation on the number of productive tillers in any cultivar except ‘Sierra’. All the cultivars except ‘Sierra’ showed increased spikelet sterility with an increase in UVB radiation. There were decreases in main-stem panicle length, number of primary branches per panicle, and grain width with an increase in UVB radiation in most of the inbred cultivars. Elevated UVB radiation decreased plant grain yield in all the cultivars, however the per cent decrease in plant grain yield varied among the cultivars (31–79 %). The hybrid ‘Clearfield XL729’ performed best among the selected southern US rice cultivars under an elevated UVB environment. [ABSTRACT FROM AUTHOR]