Effects Of ultraviolet-B Radiation Research Articles

Effects of UV-B radiation intensity and timing on epidemiological components of wheat stripe rust

Stripe rust caused by Puccinia striiformis f. sp. tritici is an important wheat disease worldwide that is greatly influenced by environmental conditions. Ultraviolet B (UV-B) radiation is one important environmental factor affecting the occurrence and epidemiology of wheat stripe rust. Investigating UV-B radiation effects on the epidemiology of stripe rust may be conducive to monitoring and predicting this disease. In this study, wheat seedlings were exposed to UV-B radiation during different periods under laboratory conditions and radiation effects on epidemiological components of wheat stripe rust were investigated. Results showed that incubation period was shortened, and the infection efficiency, sporulation quantity and disease index increased when UV-B radiation was performed only pre-inoculation. When the UV-B radiation was performed only post-inoculation or both pre- and post-inoculation, the incubation period was prolonged, and the infection efficiency, sporulation quantity and disease index were reduced. When healthy wheat seedlings were inoculated using urediospores collected from wheat leaves irradiated by UV-B only post-inoculation or both pre- and post-inoculation, infection efficiency, sporulation quantity and disease index were also reduced. However, in the latter, the disease incubation period did not differ under varying UV-B radiation intensities compared to that when wheat leaves were not treated with UV-B radiation. Overall, the effects of direct exposure of wheat plants to UV-B radiation with different intensities in different periods on epidemiological components of wheat stripe rust were systematically explored, and the results suggest that the effects of UV-B radiation increased gradually with the increase of UV-B radiation intensity. This information provides a basis for monitoring and predicting this disease as well as for conducting further studies on pathogen virulence variation.

Influence of enhanced ultraviolet-B radiation during rice plant growth on rice straw decomposition with nitrogen deposition

Although straw decomposition is important for ecosystem fertility and carbon balance, influence of ultraviolet-B (UV-B) radiation and nitrogen (N) deposition on this process is unclear. In this study, UV-B-exposed rice straw was decomposed under different N addition treatments for 15 months to investigate the indirect effects of UV-B radiation on straw chemistry and direct effects of N deposition on decomposition. UV-B exposure during rice plant growth changed the rice straw chemical composition, increasing the concentrations of acid-insoluble fraction (AIF), acid-soluble fraction, and UV-B-absorbing compounds. High N content had a negative effect on decomposition of rice straw exposed to enhanced and ambient UV-B radiation. Both AIF concentration and FTIR peak intensities indicated that lignin in rice straw was selectively preserved following N addition and UV-B radiation, reducing straw decomposition rate, which corresponded to lower activities of lignin-degrading enzymes in the later stage of decomposition. Thus, enhanced UV-B radiation during rice plant growth produced more recalcitrant substrates (lignin) and N reacted with lignin to produce more resistant compounds, further decreasing straw decomposition rate. UV-B radiation during plant growth and N deposition inhibit litter decomposition in agroecosystem, and their effects should be considered when establishing biogeochemical models in response to global changes.

Effects of natural solar UV-B radiation on three Arabidopsis accessions are strongly affected by seasonal weather conditions

Large numbers of studies have reported on the responses of plants that are exposed to a specific dose of ultraviolet-B (UV-B) radiation. However, in the natural environment UV-B is a highly dynamic variable with UV-B intensities depending on, amongst others, geographic, temporal, weather and climatic factors. Furthermore, UV-B effects on plants can potentially be modulated by other environmental variables, and vice versa. This study aimed to characterize UV-B effects on plant morphology and accumulation of UV-screening pigments within the context of an oceanic climate and to assess the potential seasonality of plant UV-B responses. Arabidopsis thaliana was grown outdoors under UV-blocking or transmitting filters. Genotypic differences in the adaptive response to UV-B were assessed at seven time-points over a 12 month period and involved the Arabidopsis accessions Ler, Col-0, and Bur-0. Strong seasonal effects were found on rosette morphology and total UV-screening pigment concentrations across the three accessions. Low temperatures were the main determinant of accumulation of UV-absorbing pigments, with no clear UV-B effect observed at any time throughout the year. There was a significant UV effect on morphology during the summer months, and this was most likely associated with stress. This study shows that UV-effects need to be analysed in the context of weather, and other co-occurring natural factors, and emphasizes the importance of a holistic, multifactorial approach for the investigation of environmentally relevant UV-effects.

Effect of pterostilbene on the expression and activity of antioxidant enzymes in ultraviolet B-radiated HaCaT Cells

Objective To evaluate the protective effect of pterostilbene against ultraviolet B (UVB) -induced acute damage in HaCaT cells, and to explore related mechanisms. Methods The 3- (4, 5-dimethylthiazol-2-yl) -5- (3-carboxymethoxyphenyl) -2- (4-sulfophenyl) -2H-tetrazolium (MTS) assay and flow cytometry were performed to estimate the proliferative activity and the apoptosis and necrosis rate of HaCaT cells treated with different concentrations of pterostilbene respectively, so as to screen the non-toxic concentration of pterostilbene. HaCaT cells were randomly divided into several groups: normal control group receiving no treatment, UVB group irradiated with 57 mJ/cm2 UVB, 3 pterostilbene groups treated with 2.44, 4.88 and 9.75 μmol/L pterostilbene respectively for 24 hours, 3 pterostilbene+ UVB groups treated with 2.44, 4.88 and 9.75 μmol/L pterostilbene respectively for 24 hours followed by UVB radiation. Western blot analysis was conducted to detect changes of the transcription factor NF-E2-related factor 2 (Nrf2) expression in cell nuclei and cytoplasm before and after the treatment with pterostilbene and UVB,quantitative PCR to determine the mRNA expression of catalase and superoxide dismutase in the HaCaT cells, and enzyme-linked immunosorbent assay (ELISA) to evaluate the activity of catalase and superoxide dismutase. Results MTS assay and flow cytometry showed that 2.44, 4.88 and 9.75 μmol/L pterostilbene had non-toxic effect on HaCaT cells. The protein expression of Nrf2 in the nuclei and cytoplasm in the normal control group was 1.03 ± 0.08 and 1.04 ± 0.11 respectively. Compared with the normal control group, the protein expression of Nrf2 in the nuclei and cytoplasm experienced no significant changes in the 2.44-, 4.88- and 9.75-μmol/L pterostilbene groups, and the UVB group showed similar protein expression of Nrf2 in the cytoplasm, but significantly increased protein expression of Nrf2 in the nuclei (1.77 ± 0.08, q= 17.24, P 0.05) . The mRNA expression of CAT and SOD experienced no significant changes in the 2.44-, 4.88- and 9.75-μmol/L pterostilbene groups compared with the normal control group (P > 0.05) . However, 2.44, 4.88 and 9.75 μmol/L pterostilbene could significantly reduce the inhibitory effect of UVB radiation on the mRNA expression of CAT (P < 0.05) and up-regulate the mRNA expression of SOD in the pterostilbene+ UVB groups (P < 0.05) . ELISA revealed that UVB radiation could inhibit the activity of CAT and SOD in the HaCaT cells (both P < 0.001) , while 2.44, 4.88 and 9.75 μmol/L pterostilbene could reduce the inhibitory effect of UVB radiation on the activity of CAT and SOD (all P < 0.05) . However, the activity of CAT and SOD were still lower in the 2.44-, 4.88- and 9.75-μmol/L pterostilbene + UVB groups than in the normal control group (P < 0.05) . Conclusion Pterostilbene can prevent UVB-induced acute damage in HaCaT cells by activating the Nrf2 pathway and up-regulating the expression of the downstream antioxidant enzymes CAT and SOD. Key words: Veratrum; NF-E2-related factor 2; Catalase; Superoxide dismutase; Ultraviolet rays; Pterostilbene; HaCaT cells

减弱UV-B辐射对低纬高原烤烟农艺性状的影响

减弱UV-B辐射对低纬高原烤烟农艺性状的影响

Combined Effects of Elevated O3 Concentrations and Enhanced UV-B Radiation of the Biometric and Biochemical Properties of Soybean Roots.

Enhanced ultraviolet-B (UV-B) radiation and elevated tropospheric ozone alone may inhibit the growth of agricultural crops. However, research regarding their combined effects on growth and biochemical properties of roots is still scarce. Using open top chambers, we monitored the response of growth, secondary metabolites, endogenous hormones and enzyme activities of soybean roots to elevated O3 and enhanced UV-B individually and in combination at stages of branching, flowering and podding. Our results indicated that the root biomass decreased by 23.6, 25.2, and 27.7%, and root oxidative capacity declined by11.2, 39.9, and 55.7% exposed to elevated O3, enhanced UV-B, and O3 + UV-B, respectively, compared to the control treatment. Concentrations of quercetin and ABA were significantly increased, while concentrations of total polyphenol and P-coumaric acid responded insignificantly to elevated O3, enhanced UV-B, and O3 + UV-B during the whole period of soybean growth. Elevated O3, enhanced UV-B and O3 + UV-B showed significant negative effects on superoxide dismutase (EC 1.15.1.1) activity at flowering stage, on activities of peroxidase (EC 1.11.1.7) and catalase (EC 1.11.1.6) at podding stage, on ascorbate peroxidase activity during the whole period of soybean growth. Moreover, compared to hormones and enzyme activity, secondary metabolisms showed stronger correlation with root growth exposed to elevated O3 and enhanced UV-B individually and in combination. Our study concluded that combined effects of O3 and UV-B radiation significantly exacerbated the decline of soybean root growth, and for annual legumes, the inhibited root growth exposed to O3 and/or UV-B radiation was mostly associated with secondary metabolisms (especially flavonoids).

The effects of ultraviolet radiation on the brown midrib mutants of Zea mays and Sorghum bicolor

The brown-midrib varieties (bm/bmr) of corn (Zea mays) and sorghum (Sorghum bicolor) have gained attention as both forage material and feedstock for biofuel. These varieties are attractive due to their low-lignin content resulting from alterations in the phenylpropanoid pathway. These bm/bmr varieties have impaired activity of cinnamyl alcohol dehydrogenase (CAD) or caffeate/5 hydroxyferulate O-methyl transferase (COMT) enzymes. We examined the effects of ultraviolet-B radiation (UV-B; 280–320 nm) on bm3 corn and bmr6 sorghum growing in a UV-transparent greenhouse in southern Minnesota. Plants grew under filters that either transmitted 2.8% (mylar) or 90% (aclar) of UV-B for 71 days. We monitored UV-screening effectiveness and chlorophyll fluorescence of leaves with pulse-amplitude modulated fluorometers. In order to explain differences in UV-screening effectiveness, we estimated concentrations of bulk-soluble UV-absorbing compounds (λ = 300 and 370 nm). We also measured final cellulose, hemicellulose and lignin concentrations of plants using a fiber analyzer. Epidermal transmittance of UV was reduced under aclar filters in both species and decreased from 41.6 to 1.9% in corn and 66.4 to 0.98% in sorghum. Increased epidermal screening may be related to the 35–39 and 37–54% higher concentrations of UV-absorbing compounds in plants growing under aclar. Concentrations of lignin were 1.7% lower in corn and 1.1% higher in sorghum in plants under aclar treatments. These contrasting results may be the result of alterations in the phenylpropanoid pool associated with each bm/bmr variety.

Solar UV-B radiation modulates chemical defenses against Anticarsia gemmatalis larvae in leaves of field-grown soybean

Although it is well known that solar ultraviolet B (UV-B) radiation enhances plant defenses, there is less knowledge about traits that define insect resistance in field-grown soybean. Here we study the effects of solar UV-B radiation on: a) the induction of phenolic compounds and trypsin proteinase inhibitors (TPI) in soybean undamaged leaves or damaged by Anticarsia gemmatalis neonates during six days, and b) the survival and mass gain of A. gemmatalis larvae that fed on soybean foliage. Two soybean cultivars (cv.), Charata and Williams, were grown under plastic with different transmittance to solar UV-B radiation, which generated two treatments: ambient UV-B (UVB+) and reduced UV-B (UVB−) radiation. Solar UV-B radiation decreased survivorship by 30% and mass gain by 45% of larvae that fed on cv. Charata, but no effect was found in those larvae that fed on cv. Williams. TPI activity and malonyl genistin were induced by A. gemmatalis damage in both cultivars, but solar UV-B radiation and damage only synergistically increased the induction of these compounds in cv. Williams. Although TPI activity and genistein derivatives were induced by herbivory, these results did not explain the differences found in survivorship and mass gain of larvae that fed on cv. Charata. However, we found a positive association between lower larval performance and the presence of two quercetin triglycosides and a kaempferol triglycoside in foliage of cv. Charata, which were identified by HPLC-DAD/MS2. We conclude that exclusion of solar UV-B radiation reduce resistance to A. gemmatalis, due to a reduction in flavonol concentration in a cultivar that has low levels of genistein derivatives like cv. Charata.

Effects of UV-B radiation on leaf hair traits of invasive plants-Combining historical herbarium records with novel remote sensing data.

Ultraviolet-B (UV-B) radiation is a key but under-researched environmental factor that initiates diverse responses in plants, potentially affecting their distribution. To date, only a few macroecological studies have examined adaptations of plant species to different levels of UV-B. Here, we combined herbarium specimens of Hieracium pilosella L. and Echium vulgare L. with a novel UV-B dataset to examine differences in leaf hair traits between the plants’ native and alien ranges. We analysed scans of 336 herbarium specimens using standardized measurements of leaf area, hair density (both species) and hair length (H. pilosella only). While accounting for other bioclimatic variables (i.e. temperature, precipitation) and effects of herbivory, we examined whether UV-B exposure explains the variability and geographical distribution of these traits in the native (Northern Hemisphere) vs. the alien (Southern Hemisphere) range. UV-B explained the largest proportion of the variability and geographical distribution of hair length in H. pilosella (relative influence 67.1%), and hair density in E. vulgare (66.2%). Corresponding with higher UV-B, foliar hairs were 25% longer for H. pilosella and 25% denser for E. vulgare in records from the Southern as compared to those from the Northern Hemisphere. However, focusing on each hemisphere separately or controlling for its effect in a regression analysis, we found no apparent influence of UV-B radiation on hair traits. Thus, our findings did not confirm previous experimental studies which suggested that foliar hairs may respond to higher UV-B intensities, presumably offering protection against detrimental levels of radiation. We cannot rule out UV-B radiation as a possible driver because UV-B radiation was the only considered variable that differed substantially between the hemispheres, while bioclimatic conditions (e.g. temperature, precipitation) and other considered variables (herbivory damage, collection date) were at similar levels. However, given that either non-significant or inconclusive relationships were detected within hemispheres, alternative explanations of the differences in foliar hairs are more likely, including the effects of environment, genotypes or herbivory.

Ultraviolet-B radiation mobilizes uranium from uranium-dissolved organic carbon complexes in aquatic systems, demonstrated by asymmetrical flow field-flow fractionation

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.

Effect of Elevated UV-B Radiation on Microbial Biomass C and Soil Respiration in Different Barley Cultivars Under Field Conditions

Elevated ultraviolet-B (UV-B) radiation effect on soil carbon (C) cycling has been regarded as one of the important issues in global change. Field simulating experiment was conducted to investigate the effects of elevated UV-B radiation on the content of microbial biomass C in rhizosphere and non-rhizosphere soils as well as soil respiration in three barley cultivars. The UV-B radiation was set at two levels, i.e., reference (A, ambient UV-B radiation), and elevated by 20% (E, elevated UV-B radiation, 14.4 kJ m−2 day−1). Three barley cultivars were tested including Dan 2, Supi 3, and Supi 4, respectively. The results indicated that elevated UV-B radiation obviously decreased the content of microbial biomass C in rhizosphere and non-rhizosphere soil, but had no effect on the tendency of microbial biomass C in rhizosphere and non-rhizosphere soil during the entire barley growing season. Compared with control (ambient UV-B radiation), elevated UV-B radiation depressed soil respiration rate and its temperature sensitivity coefficients (Q10), especially in barley cultivar Dan 2 and cultivar Supi 3. It is suggested that the different responses of three barley cultivars to elevated UV-B radiation were related to the changes of microbial biomass C and soil respiration.

Exogenous 5-aminolevulinic acid alleviates the detrimental effects of UV-B stress on lettuce (Lactuca sativa L) seedlings

One of the abiotic stress factors affecting plant metabolism is ultraviolet-B (UV-B) radiation. 5-Aminolevulinic acid (ALA), a key precursor of porphyrin biosynthesis, promotes plant growth and crop yields. To investigate the alleviating effects of exogenous ALA on the damages caused by UV-B exposure, two different concentrations [10 ppm (ALA1) and 25 ppm (ALA2)] of ALA were applied to lettuce seedlings for 24 h and then they were exposed to 3.3 W m−2 UV-B. Results showed that UV-B treatment significantly decreased chlorophyll a and b (Chl a and b) concentration, enhanced the activity of antioxidant enzymes, total phenolic concentration, soluble sugar contents, expression of phenylalanine ammonia lyase (PAL) and γ-tocopherol methyltransferase (γ-TMT) genes, the concentration of malondialdehyde (MDA), hydrogen peroxide (H2O2), and the rate of superoxide radical ( $${\text{O}}_{2}^{ - }$$ ) generation in the lettuce seedlings when compared to the control. Pre-treatment with exogenous ALA significantly enhanced UV-B stress tolerance in lettuce seedlings by decreasing the reactive oxygen species. On the other hand, ALA application caused more increases in the PAL and γ-TMT gene expression, antioxidant enzymes activities, Chl a and b concentration, total phenolic content, antioxidant capacity and the concentrations of soluble sugars. Obtained results indicated that UV-B radiation exerts an adverse effect on lettuce seedlings, and some of the negative effects of UV-B radiation can be alleviated by exogenous ALA.

Interactive effects of temperature and UVB radiation on methane emissions from different organs of pea plants grown in hydroponic system

There is no information on variation of methane (CH4) emissions from plant organs exposed to multiple environmental factors. We investigated the interactive effects of temperature and ultraviolet-B (UVB) radiation on CH4 emissions from different organs of pea (Pisum sativum L. var. UT234 Lincoln). Plants were grown hydroponically under two temperatures (22/18°C and 28/24°C; 16h day/8h night) and two levels of UVB radiation [0 and 5kJm−2 d−1] in controlled-environment growth chambers for ten days, after two weeks of initial growth under ambient temperatures. Methane emission, dry mass, growth index, electrical conductivity (EC), pectin, total chlorophyll content, gas exchange and flavonoids were measured in the appropriate plant organs – leaf, stem and root. Higher temperatures increased CH4 emissions, leaf mass ratio, and shoot: root mass ratio. Neither temperature nor UVB had significant effects on leaf, stem, root and total dry mass, EC, pectin, total chlorophyll, as well as specific leaf mass. Among plant organs, there were differences in CH4, EC, pectin and total chlorophyll. Methane and EC were highest for the stem and lowest for the leaf; leaf had highest, but stem had lowest, pectin content; total chlorophyll was highest in the leaf but lowest in the root. Higher temperatures decreased leaf flavonoids, net carbon dioxide assimilation, and water use efficiency. Overall, environmental stressors increased aerobic CH4 emission rates, which varied with plant organs.

Detection of Free Thiols and Fluorescence Response of Phycoerythrin Chromophore after Ultraviolet-B Radiation Stress

The chemistry of thiol-chromophore linkage plays a central role in the nature of fluorescence of phycoerythrin (PE). Interaction of thiol and chromophore is crucial for the energy transfer, redox signal and inhibition of oxidative damage. In the present investigation the effects of ultraviolet-B radiation on an emission fluorescence intensity and wavelength shift in PE due to interaction between thiol and chromophore by remarkable strategy of detection technique was studied. Purification of PE was done by using a gel permeation and ion exchange chromatography that yielded a quite high purity index (6.40) in a monomeric (αβ) form. UV-B radiation accelerated the quenching efficiency (24.9±1.52%) by reducing fluorescence emission intensity of thiol linked chromophore after 240min of UV-B exposure. However, after blocking of transiently released free thiol by N-ethylmaleimide, quenching efficiency was increased (36.8±2.80%) with marked emission wavelength shift towards shorter wavelengths up to 562nm as compared to 575nm in control. Emission fluorescence of free thiol was at maximum after 240min that was detected specifically by monobromobimane (mBrB) molecular probe. The association/dissociation of bilin chromophore was analyzed by SDS- and Native-PAGE that also indicated a complete reduction in emission fluorescence. Our work clearly shows an early detection of free thiols and relative interaction with chromophore after UV-B radiation which might play a significant role in structural and functional integrity of terminal PE.

Effects of UVB radiation on net community production in the upper global ocean

AbstractAimErosion of the stratospheric ozone layer together with oligotrophication of the subtropical ocean is leading to enhanced exposure to ultraviolet B (UVB) radiation in ocean surface waters. The impact of increased exposure to UVB on planktonic primary producers and heterotrophs is uncertain. Here we test the null hypothesis that net community production (NCP) of plankton communities in surface waters of the tropical and subtropical ocean is not affected by ambient UVB radiation and extend this test to the global ocean, including the polar oceans and the Mediterranean Sea using previous results.LocationWe conducted experiments with 131 surface communities sampled during a circumnavigation cruise along the tropical and subtropical ocean and combined these results with 89 previous reports encompassing the Atlantic, Pacific, Arctic and Southern Oceans and the Mediterranean Sea.MethodsThe use of quartz (transparent to UVB radiation) and borosilicate glass materials (opaque to most UVB) for incubations allowed us to compare NCP between communities where UVB is excluded and those receiving natural UVB radiation.ResultsWe found that NCP varies when exposed to natural UVB radiation compared to those where UVB was removed. NCP of autotrophic communities tended to decrease under natural UVB radiation, whereas the NCP of heterotrophic communities tended to increase. However, these variations showed the opposite trend under higher levels of UVB radiation.Main conclusionsOur results suggest that earlier estimates of NCP for surface communities, which were hitherto derived using materials blocking UVB radiation were biased, with the direction and magnitude of this bias depending on the metabolic status of the communities and the underwater penetration of UVB radiation.

Photo-protective effect of sargachromenol against UVB radiation-induced damage through modulating cellular antioxidant systems and apoptosis in human keratinocytes.

The aim of this study was to evaluate the photo-preventive effects of sargachromenol (SC) against ultraviolet B (UVB)-induced oxidative stress in human keratinocytes via assessing the antioxidant properties and underlying molecular mechanisms. SC exhibited a significant scavenging effect on UVB-induced intracellular reactive oxygen species (ROS). SC attenuated UVB-induced oxidative macromolecular damage, including the protein carbonyl content, DNA strand break, and 8-isoprostane level. Furthermore, SC decreased UVB-induced Bax, cleaved caspase-9, and cleaved caspase-3 protein levels, but increased that of Bcl-2, which are well-known key mediators of apoptosis. Moreover, SC increased superoxide dismutase, catalase, and heme oxygenase-1 protein expression. Pre-treatment with SC upregulated the main transcription factor of antioxidant enzymes, erythroid 2-related factor 2 level, which was reduced by UVB irradiation. Extracellular signal-regulated kinase (ERK) and Jun N-terminal kinases (JNK) are involved in the regulation of many cellular events, including apoptosis. SC treatment reversed ERK and JNK activation induced by UVB. Collectively, these data indicate that SC can provide remarkable cytoprotection against the adverse effects of UVB radiation by modulating cellular antioxidant systems, and suggest the potential of developing a medical agent for ROS-induced skin diseases.

Effect of supplemental UV-B on yield, seed quality, oil content and fatty acid composition ofBrassica campestrisL. under natural field conditions

Thinning of stratospheric ozone layer had been reported since last fifty years due to emission of chlorofluorocarbons, resulting in an increase in ultraviolet-B (UV-B) radiation. The present study was conducted to examine the effects of supplemental UV-B (sUV-B) radiation (+7.2 kJ/m2/s) on yield and quality of seeds and oil of two cultivars of mustard, (Brassica campestris) L. cv. Sanjukta and Vardan. Number of pods, harvest index, test weight and oil content decreased due to sUV-B exposure in both cultivars. Seed quality was also reduced under sUV-B in terms of protein, sugar and amino acid contents. Further, quality of oil was deteriorated due to increases in erucic acid, polyunsaturated fatty acid and ω-6 fatty acid contents and reductions in oleic acid and nervonic acid contents due to sUV-B exposure. Cultivar Vardan showed more negative impact on seed yield due to UV-B stress, whereas quality of seed and oil was more affected in Sanjukta. Results of the present study confirmed the potential loss in y...

Photoprotective Effect of Carpomitra costata Extract against Ultraviolet B-Induced Oxidative Damage in Human Keratinocytes.

Natural marine products show various biological properties such as antiphotoaging, antioxidant, anticancer, and anti-inflammation. This study evaluated the protective effects of the brown alga Carpomitra costata (Stackhouse) Batters (Sporochnaceae) against ultraviolet B (UVB)-provoked damage in human HaCaT keratinocytes. C. costata extract (CCE) effectively reduced superoxide anion, hydroxyl radical, and UVB-stimulated intracellular reactive oxygen species (ROS) levels. CCE also restored the expression and activity of UVB-suppressed antioxidant enzymes. Furthermore, CCE decreased UVB-triggered oxidative damage to cellular components including DNA, protein, and lipid and defended the cells against mitochondrial membrane depolarization-medicated apoptosis. The results of this study indicate that CCE can safeguard human keratinocytes against UVB-induced cellular damage via a potent antioxidant mechanism. CCE may find utility as part of a therapeutic arsenal against the damaging effects of UVB radiation on the skin.

Rosmarinic Acid Attenuates Cell Damage against UVB Radiation-Induced Oxidative Stress via Enhancing Antioxidant Effects in Human HaCaT Cells.

This study was designed to investigate the cytoprotective effect of rosmarinic acid (RA) on ultraviolet B (UVB)-induced oxidative stress in HaCaT keratinocytes. RA exerted a significant cytoprotective effect by scavenging intracellular ROS induced by UVB. RA also attenuated UVB-induced oxidative macromolecular damage, including protein carbonyl content, DNA strand breaks, and the level of 8-isoprostane. Furthermore, RA increased the expression and activity of superoxide dismutase, catalase, heme oxygenase-1, and their transcription factor Nrf2, which are decreased by UVB radiation. Collectively, these data indicate that RA can provide substantial cytoprotection against the adverse effects of UVB radiation by modulating cellular antioxidant systems, and has potential to be developed as a medical agent for ROS-induced skin diseases.

Early exposure to ultraviolet-B radiation decreases immune function later in life.

Amphibians have declined dramatically worldwide. Many of these declines are occurring in areas where no obvious anthropogenic stressors are present. It is proposed that in these areas, environmental factors such as elevated solar ultraviolet-B (UV-B) radiation could be responsible. Ultraviolet-B levels have increased in many parts of the world as a consequence of the anthropogenic destruction of the ozone layer. Amphibian tadpoles are particularly sensitive to the damaging effects of UV-B radiation, with exposure disrupting growth and fitness in many species. Given that UV-B can disrupt immune function in other animals, we tested the hypothesis that early UV-B exposure suppresses the immune responses of amphibian tadpoles and subsequent juvenile frogs. We exposed Limnodynastes peronii tadpoles to sublethal levels of UV-B radiation for 6 weeks after hatching, then examined indices of immune function in both the tadpoles and the subsequent metamorphs. There was no significant effect of UV-B on tadpole leucocyte counts or on their response to an acute antigen (phytohaemagglutinin) challenge. However, early UV-B exposure resulted in a significant reduction in both metamorph leucocyte abundance and their response to an acute phytohaemagglutinin challenge. These data demonstrate that early UV-B exposure can have carry-over effects on later life-history traits even if the applied stressor has no immediately discernible effect. These findings have important implications for our understanding of the effects of UV-B exposure on amphibian health and susceptibility to diseases such as chytridiomycosis.