UVB Dose Research Articles

Protective effect and mechanism of lycium barbarum polysaccharide against UVB-induced skin photoaging.

Cellular senescence can be categorized into two main types, including exogenous and endogenous aging. Photoaging, which is aging induced by ultraviolet (UV) radiation, significantly contributes to exogenous aging, accounting for approximately 80% of such cases. Superoxide Dismutase (SOD) is a class of antioxidant enzymes, with SOD2 being predominantly localized in the mitochondrial matrix. Ultraviolet radiation (UVR) inhibits SOD2 activity by acetylating the key lysine residues on SOD2. Sirtuin3 (SIRT3), the principal mitochondrial deacetylase, enhances the anti-oxidant capacity of SOD2 by deacetylating. Lycium barbarum polysaccharide (LBP) is the main bioactive component extracted from Lycium barbarum (LB). It has been reported to have numerous potential health benefits, such as anti-oxidation, anti-aging, anti-inflammatory and anti-apoptotic properties. Furthermore, LBP has been shown to regulate hepatic oxidative stress via the SIRT3-SOD2 pathway. The aim of this study was to construct a UVB-Stress-induced Premature Senescence (UVB-SIPS) model to investigate the protective effects and underlying mechanisms of LBP against UVB-induced skin photoaging. Irradiated with different UVB doses to select the suitable dose for constructing the UVB-SIPS model. Cell morphology was observed using a microscope. The proportion of senescent cells was assessed by senescence-associated β-galactosidase (SA-β-gal) staining. Cell viability was studied using the Cell Counting Kit-8 (CCK-8). Intracellular levels of reactive oxygen species (ROS) were observed using flow cytometry and an inverted fluorescence microscope. Expression of γ-H2AX was investigated using flow cytometry. Western blot (WB) was used to verify the expression of senescence-associated proteins (p21, p53, MMP-1, and MMP-3). Enzyme-Linked Immunosorbnent Assay (ELISA) was used to measure pro-inflammatory cytokines levels (IL-6, TNF-α). WB was also used to analyze the expression of SIRT3, SOD2, and Ac-SOD2, and a specific kit was employed to detect SOD2 activity. Our results suggested that the UVB-SIPS group pre-treated with LBP exhibited a reduced proportion of cells positive for SA-β-gal staining, mitigated production of intracellular ROS, an amelioration in γ-H2AX expression, and down-regulated expression of senescence-associated proteins and pro-inflammatory cytokines as compared to the UVB-SIPS group. Moreover, in contrast to the control group, the UVB-SIPS group showed regulated SIRT3 expression and SOD activity, elevated Ac-SOD2 expression and an increased ratio of Ac-SOD2/SOD2. However, the UVB-SIPS group pre-treated with LBP showed an upregulation of SIRT3 expression and enhanced SOD activity, a reduction in AC-SOD2 expression, and a decreased ratio of AC-SOD2/SOD2, compared to the untreated UVB-SIPS group. Additionally, the photo-protective effect of LBP was diminished following treatment with 3-TYP, a SIRT3-specific inhibitor. This study suggested that LBP, a natural component, exhibits anti-oxidant and anti-photoaging properties, potentially mediated through the SIRT3-SOD2 pathway.

Botánica aplicada: radiación UV-B para la obtención de brotes de quinua enriquecidos en compuestos fenólicos, con probables usos en protectores solares naturales o como alimentos funcionales

The objective was to evaluate the use of a microgreen system and very short UV-B radiation dose to obtain plant biomass as a source for phenol-enriched extracts with probable cosmetic and/or food uses. Quinoa seedlings, a native species of the Andes, of two different ages were used. The seedlings were irradiated with different doses of UV-B and then evaluated by quantifying indicators of oxidative damage. Also, the contents of phenolic compounds, photosynthetic pigments, antioxidant capacity, and sun protection factor were determined. The results showed that the youngest seedlings responded better to short UVB doses, increasing the content of soluble and insoluble phenols, without showing oxidative damage. These results were correlated with the greater antioxidant power of the extracts and an intermediate sun protection factor. We conclude that this species, grown in a microgreen system, is a promising alternative to obtain phenol-enriched extracts with possible use in formulations of natural sunscreens. In this sense, these results can serve as a starting point for optimization studies through the response surface methodology.

Effect of white light combined with different UV-B doses on the anthocyanin and plant hormone accumulation in mango peel

Effect of white light combined with different UV-B doses on the anthocyanin and plant hormone accumulation in mango peel

The Role of Vitamin A on the Histology of Skin of Adult Rats After Eposure to UVB

Background: long-term eposure of skin to sun (UV light) may produce different dermatological changes. The aim of this eperiment is to eplore the protective effects of oral vitamin A on skin subjected to UVB. Methods: twenty rats were separated into: group 1 (without UVB eposure), group 2 (eposed to single daily increasing dose of UVB for one week), group 3 (eposed to UVB with oral daily administration of vit A 10000 IU for one week), group 4 (received vit A for one week). The daily doses of UVB were respectively 0.24, 0.36, 0.48, 0.6, 0.72, 0.84 and 0.96 J/cm2. Skin samples were stained with hematoylin-eosin and Masson’s trichrome stains, in addition to Melan-A stain for melanocytes. Results: histopathological results in skin of group 2 demonstrated loss of normal architecture with increase in thickness of epidermis, hyperkeratosis and parakeratosis, moreover, skin sections detected increased number of inflammatory cells with damaged hair follicles. The basal layer shows an increase in mitotic division and necrosis, besides, epidermal edema and vascular congestion. Furthermore, collagen fibers were degraded. Immunohistochemical reaction revealed intense positive epression of Melan-A with increased proliferation and activity of melanocytes, while sections of groups 1 and 4 show normal healthy skin and negative Melan-A epression. In contrast, skin of group 3 reveals mild hyperkeratosis with normal keratin layer, in addition, the infiltration of inflammatory cells was dropped and hair follicles were preserved. Collagen bundles were slightly degraded with normal arrangement. Immunohistochemical results of this group show mild positive epression of Melan A. Conclusion: oral administration of vitamin A decreases the toic effect of UVB radiation on skin and reduces its induced pigmentation.

Postharvest white light combined with different UV-B doses differently promotes anthocyanin accumulation and antioxidant capacity in mango peel

Fruit peel color is an important index of mango fruit quality. Therefore, increasing the anthocyanin accumulation and improving coloration in red mango are crucial for mango industry. The anthocyanin accumulation in mango is light-regulated. However, the effect of white light combined with different doses of UV-B on anthocyanin biosynthesis has not been clarified. Also lacking is a comprehensive analysis of responses of mango fruit peel to UV-B/white light treatments. In this study, green mature ‘Guifei’ mango fruits were subjected to white light combined with low (WL + UV-BL) or high dose UV-B (WL + UV-BH). Anthocyanin concentration, anthocyanin-related gene expression, reactive oxygen species (ROS), antioxidant, and plant hormone concentrations, and antioxidant enzyme activity were measured. The results showed that especially a WL + UV-BH regimen promoted anthocyanin formation in mango peel. Anthocyanin- and light signal-related gene expression, ROS content, antioxidant enzyme activity, antioxidant concentrations, and total antioxidant capacity were also increased by UV-B/white light. Such treatments led to higher concentrations of jasmonic acid and cytokinin, but decreased content of 1-aminocyclopropane-1-carboxylic acid and salicylic acid. Commercially, our findings may contribute to improving the commercial quality of mango. Scientifically, the present data sheds light on the mango fruit peel-specific molecular and physiological response network under UV-B/white light treatments.

Comprehensive Modulation of Secondary Metabolites in Terpenoid-Accumulating Mentha spicata L. via UV Radiation.

In plants, secondary metabolites change in response to environmental conditions. These changes co-regulate resilience to stressful environmental conditions, plant growth and development, and interactions between plants and the wider ecosystem, while also affecting soil carbon storage and atmospheric and climatic conditions. The objective of this study was to determine the association between UV exposure and the contents of key metabolites, including amino acids, phenolics, flavonoids, terpenoids, carotenoids, tocopherols, and phytosterols. Mentha spicata plantlets were grown in tissue culture boxes for 30 days and then exposed to a low dose of broadband UV-B (291-315 nm; 2.8 kJm-2 biologically effective UV) enriched light for eight days. Metabolite contents were quantified either immediately after the final UV exposure, or after seven days of recovery under photosynthetically active radiation. It was found that UV promoted the production of flavonoids (1.8-fold) ahead of phenolic acids (unchanged). Furthermore, the majority of monoterpenes and sesquiterpenes, constituents of valuable mint essential oil, were significantly increased through UV treatment (up to 90-fold for α-linalool). In contrast, the contents of carotenoids and tocopherols did not increase following UV exposure. A comparison between plants sampled immediately after UV exposure and after seven days of recovery showed that there was an overall increase in the content of carotenoids, mono- and sesquiterpenes, phenolics, and amino acids following recovery, while the contents of sterols and tocopherols decreased. These UV-induced changes in metabolite profile may have important consequences for agriculture, ecology, and even the global climate, and they also provide an exciting opportunity to enhance crop value, facilitating the development of improved products with higher levels of essential oils and added benefits of enhanced flavour, colour, and bioactive content.

UV light and adaptive divergence of leaf physiology, anatomy, and ultrastructure drive heat stress tolerance in genetically distant grapevines.

The genetic basis of plant response to light and heat stresses had been unveiled, and different molecular mechanisms of leaf cell homeostasis to keep high physiological performances were recognized in grapevine varieties. However, the ability to develop heat stress tolerance strategies must be further elucidated since the morpho-anatomical and physiological traits involved may vary with genotype × environment combination, stress intensity, and duration. A 3-year experiment was conducted on potted plants of Sardinian red grapevine cultivars Cannonau (syn. Grenache) and Carignano (syn. Carignan), exposed to prolonged heat stress inside a UV-blocking greenhouse, either submitted to low daily UV-B doses of 4.63 kJ m-2 d-1 (+UV) or to 0 kJ m-2 d-1 (-UV), and compared to a control (C) exposed to solar radiation (4.05 kJ m-2 d-1 average UV-B dose). Irrigation was supplied to avoid water stress, and canopy light and thermal microclimate were monitored continuously. Heat stress exceeded one-third of the duration inside the greenhouse and 6% in C. In vivo spectroscopy, including leaf reflectance and fluorescence, allowed for characterizing different patterns of leaf traits and metabolites involved in oxidative stress protection. Cannonau showed lower stomatal conductance under C (200 mmol m-2 s-1) but more than twice the values inside the greenhouse (400 to 900 mmol m-2 s-1), where water use efficiency was reduced similarly in both varieties. Under severe heat stress and -UV, Cannonau showed a sharper decrease in primary photochemical activity and higher leaf pigment reflectance indexes and leaf mass area. UV-B increased the leaf pigments, especially in Carignano, and different leaf cell regulatory traits to prevent oxidative damage were observed in leaf cross-sections. Heat stress induced chloroplast swelling, plastoglobule diffusion, and the accumulation of secretion deposits in both varieties, aggravated in Cannonau -UV by cell vacuolation, membrane dilation, and diffused leaf blade spot swelling. Conversely, in Carignano UV-B, cell wall barriers and calcium oxalate crystals proliferated in mesophyll cells. These responses suggest an adaptive divergence among cultivars to prolonged heat stress and UV-B light. Further research on grapevine biodiversity, heat, and UV-B light interactions may give new insights on the extent of stress tolerance to improve viticulture adaptive strategies in climate change hotspots.

Photoreactivation Activities of Rad5, Rad16A and Rad16B Help Beauveria bassiana to Recover from Solar Ultraviolet Damage.

In budding yeast, Rad5 and Rad7-Rad16 play respective roles in the error-free post-replication repair and nucleotide excision repair of ultraviolet-induced DNA damage; however, their homologs have not yet been studied in non-yeast fungi. In the fungus Beauveria bassiana, a deficiency in the Rad7 homolog, Rad5 ortholog and two Rad16 paralogs (Rad16A/B) instituted an ability to help the insect-pathogenic fungus to recover from solar UVB damage through photoreactivation. The fungal lifecycle-related phenotypes were not altered in the absence of rad5, rad16A or rad16B, while severe defects in growth and conidiation were caused by the double deletion of rad16A and rad16B. Compared with the wild-type and complemented strains, the mutants showed differentially reduced activities regarding the resilience of UVB-impaired conidia at 25 °C through a 12-h incubation in a regime of visible light plus dark (L/D 3:9 h or 5:7 h for photoreactivation) or of full darkness (dark reactivation) mimicking a natural nighttime. The estimates of the median lethal UVB dose LD50 from the dark and L/D treatments revealed greater activities of Rad5 and Rad16B than of Rad16A and additive activities of Rad16A and Rad16B in either NER-dependent dark reactivation or photorepair-dependent photoreactivation. However, their dark reactivation activities were limited to recovering low UVB dose-impaired conidia but were unable to recover conidia impaired by sublethal and lethal UVB doses as did their photoreactivation activities at L/D 3:9 or 5:7, unless the night/dark time was doubled or further prolonged. Therefore, the anti-UV effects of Rad5, Rad16A and Rad16B in B. bassiana depend primarily on photoreactivation and are mechanistically distinct from those for their yeast homologs.

Cancer Incidence Rates in the US in 2016-2020 with Respect to Solar UVB Doses, Diabetes and Obesity Prevalence, Lung Cancer Incidence Rates, and Alcohol Consumption: An Ecological Study.

This article reports the results of an ecological study of cancer incidence rates by state in the US for the period 2016-2020. The goals of this study were to determine the extent to which solar UVB doses reduced cancer risk compared to findings reported in 2006 for cancer mortality rates for the periods 1950-1969 and 1970-1794 as well as cancer incidence rates for the period 1998-2002 and to determine which factors were recently associated with cancer risk. The cancer data for non-Hispanic white (European American) men and women were obtained from the Centers for Disease Control and Prevention. Indices were obtained for solar UVB at the surface for July 1992, and alcohol consumption, diabetes, and obesity prevalence near the 2016-2020 period. Lung cancer incidence rates were also used in the analyses as a surrogate for smoking, diet, and air pollution. The cancers for which solar UVB is significantly associated with reduced incidence are bladder, brain (males), breast, corpus uteri, esophageal, gastric, non-Hodgkin's lymphoma, pancreatic, and renal cancer. Lung cancer was significantly associated with colorectal, laryngeal, and renal cancer. Diabetes was also significantly associated with breast, liver, and lung cancer. Obesity prevalence was significantly associated with breast, colorectal, and renal cancer. Alcohol consumption was associated with bladder and esophageal cancer. Thus, diet has become a very important driver of cancer incidence rates. The role of solar UVB in reducing the risk of cancer has been reduced due to people spending less time outdoors, wearing sunscreen that blocks UVB but not UVA radiation, and population increases in terms of overweight and obese individuals, which are associated with lower 25-hydroxyvitamin D concentrations and the generation of systemic inflammation, which is a risk factor for cancer. A dietary approach that would reduce the risk of diabetes, obesity, lung cancer, and, therefore, cancer, would be one based mostly on whole plants and restrictions on red and processed meats and ultraprocessed foods. Solar UVB exposure for a few minutes before applying sunscreen and taking vitamin D supplements would also help reduce the risk of cancer.

Weaker photosynthetic acclimation to fluctuating than to corresponding steady UVB radiation treatments in grapevines

AbstractThe effects of transient increases in UVB radiation on plants are not well known; whether cumulative damage dominates or, alternately, an increase in photoprotection and recovery periods ameliorates any negative effects. We investigated photosynthetic capacity and metabolite accumulation of grapevines (Vitis vinifera Cabernet Sauvignon) in response to UVB fluctuations under four treatments: fluctuating UVB (FUV) and steady UVB radiation (SUV) at similar total biologically effective UVB dose (2.12 and 2.23 kJ m−2 day−1), and their two respective no UVB controls. We found a greater decrease in stomatal conductance under SUV than FUV. There was no decrease in maximum yield of photosystem II (Fv/Fm) or its operational efficiency (ɸPSII) under the two UVB treatments, and Fv/Fm was higher under SUV than FUV. Photosynthetic capacity was enhanced under FUV in the light‐limited region of rapid light‐response curves but enhanced by SUV in the light‐saturated region. Flavonol content was similarly increased by both UVB treatments. We conclude that, while both FUV and SUV effectively stimulate acclimation to UVB radiation at realistic doses, FUV confers weaker acclimation than SUV. This implies that recovery periods between transient increases in UVB radiation reduce UVB acclimation, compared to an equivalent dose of UVB provided continuously. Thus, caution is needed in interpreting the findings of experiments using steady UVB radiation treatments to infer effects in natural environments, as the stimulatory effect of steady UVB is greater than that of the equivalent fluctuating UVB.

Hurdles in investigating UVB damage in the putative ancient asexual Darwinula stevensoni (Ostracoda, Crustacea)

Ostracoda or mussel-shrimps are small, bivalved Crustacea. Because of their excellent fossil record and their broad variety of reproductive modes, ostracods are of great interest as a model group in ecological and evolutionary research. Here, we investigated damage and repair from one of the most important biological mutagens, namely UVB radiation, in the putative ancient asexual ostracod Darwinula stevensoni from Belgium. We applied three different methods: the Polymerase Inhibition (PI) assay, Enzyme-Linked Immuno Sorbent Assay (ELISA) and dot blot. All three techniques were unsuccessful in quantifying UVB damage in D. stevensoni. Previous experiments have revealed that the valves of D. stevensoni provide an average UVB protection of approximate 60%. Thus, UVB damage could be too little to make quantitative experiments work. Additionally, variation between individual ostracods due to season and age most likely contributed further to the failure of the three used experimental approaches to quantify damage. In a second experiment, we investigated the influence of temperature on survival of D. stevensoni during UVB exposure. The estimated relative lethal UVB dose at 4°C was with 50 kJ/m2, significantly lower than at room temperature, with 130 kJ/m2. This could either indicate lack of adaptation to low temperatures and/or the presence of metabolic processes active at room temperature protecting against UVB damage in D. stevensoni. The latter possibility could also explain why the estimated relative lethal UVB dose of D. stevensoni is similar to that of other non-marine ostracods where valves provide around 80% protection, despite the valves of D. stevensoni providing less protection. If such metabolic processes can repair UVB damage quickly, this may provide an alternative explanation why we could not quantify UVB damage in D. stevensoni.

Narrow-band UVB radiation triggers diverse changes in the gene expression and induces the accumulation of M1 macrophages in human skin

BackgroundThe underlying molecular mechanisms that determine the biological effects of UVB radiation exposure on human skin are still only partially comprehended. ObjectivesOur goal is to examine the human skin transcriptome and related molecular mechanisms following a single exposure to UVB in the morning versus evening. MethodsWe exposed 20 volunteer females to four-fold standard erythema doses (SED4) of narrow-band UVB (309–313 nm) in the morning or evening and studied skin transcriptome 24 h after the exposure. We performed enrichment analyses of gene pathways, predicted changes in skin cell composition using cellular deconvolution, and correlated cell proportions with gene expression. ResultsIn the skin transcriptome, UVB exposure yielded 1384 differentially expressed genes (DEGs) in the morning and 1295 DEGs in the evening, of which the most statistically significant DEGs enhanced proteasome and spliceosome pathways. Unexposed control samples showed difference by 321 DEGs in the morning vs evening, which was related to differences in genes associated with the circadian rhythm. After the UVB exposure, the fraction of proinflammatory M1 macrophages was significantly increased at both timepoints, and this increase was positively correlated with pathways on Myc targets and mTORC1 signaling. In the evening, the skin clinical erythema was more severe and had stronger positive correlation with the number of M1 macrophages than in the morning after UVB exposure. The fractions of myeloid and plasmacytoid dendritic cells and CD8 T cells were significantly decreased in the morning but not in the evening. ConclusionsNB-UVB-exposure causes changes in skin transcriptome, inhibiting cell division, and promoting proteasome activity and repair responses, both in the morning and in the evening. Inflammatory M1 macrophages may drive the UV-induced skin responses by exacerbating inflammation and erythema. These findings highlight how the same UVB exposure influences skin responses differently in morning versus evening and presents a possible explanation to the differences in gene expression in the skin after UVB irradiation at these two timepoints.

METTL14 affects UVB-induced human dermal fibroblasts photoaging via miR-100-3p biogenesis in an m6A-dependent manner.

Exposure to ultraviolet radiation can lead to skin photoaging, which increases the risk of skin tumors. This study aims to investigate how microRNA m6A modification contributes to skin photoaging. This study found that skin fibroblasts exposed to a single UVB dose of 30 mJ/cm2 exhibited characteristics of photoaging. The m6A level of total RNA decreased in photoaged cells with a down-regulated level of METTL14, and overexpression of METTL14 displayed a photoprotective function. Moreover, miR-100-3p was a downstream target of METTL14. And METTL14 could affect pri-miR-100 processing to mature miR-100-3p in an m6A-dependent manner via DGCR8. Furthermore, miR-100-3p targeted at 3' end untranslated region of ERRFI1 mRNA with an inhibitory effect on translation. Additionally, photoprotective effects of overexpression of METTL14 were reversed by miR-100-3p inhibitor or overexpression of ERRFI1. In UVB-induced photoaging of human skin fibroblasts, METTL14-dependent m6A can regulate miR-100-3p maturation via DGCR8 and affect skin fibroblasts photoaging through miR-100-3p/ERRFI1 axis.

Q-switched 1064 nm Nd: YAG laser restores skin photoageing by activating autophagy by TGFβ1 and ITGB1.

Excessive ultraviolet B ray (UVB) exposure to sunlight results in skin photoageing. Our previous research showed that a Q-switched 1064 nm Nd: YAG laser can alleviate skin barrier damage through miR-24-3p. However, the role of autophagy in the laser treatment of skin photoageing is still unclear. This study aims to investigate whether autophagy is involved in the mechanism of Q-switched 1064 nm Nd: YAG in the treatment of skin ageing. Invitro, primary human dermal fibroblast (HDF) cells were irradiated with different doses of UVB to establish a cell model of skin photoageing. Invivo, SKH-1 hairless mice were irradiated with UVB to establish a skin photoageing mouse model and irradiated with laser. The oxidative stress and autophagy levels were detected by western blot, immunofluorescence and flow cytometer. String was used to predict the interaction protein of TGF-β1, and CO-IP and GST-pull down were used to detect the binding relationship between TGFβ1 and ITGB1. Invitro, UVB irradiation reduced HDF cell viability, arrested cell cycle, induced cell senescence and oxidative stress compared with the control group. Laser treatment reversed cell viability, senescence and oxidative stress induced by UVB irradiation and activated autophagy. Autophagy agonists or inhibitors can enhance or attenuate the changes induced by laser treatment, respectively. Invivo, UVB irradiation caused hyperkeratosis, dermis destruction, collagen fibres reduction, increased cellular senescence and activation of oxidative stress in hairless mice. Laser treatment thinned the stratum corneum of skin tissue, increased collagen synthesis and autophagy in the dermis, and decreased the level of oxidative stress. Autophagy agonist rapamycin and autophagy inhibitor 3-methyladenine (3-MA) can enhance or attenuate the effects of laser treatment on the skin, respectively. Also, we identified a direct interaction between TGFB1 and ITGB1 and participated in laser irradiation-activated autophagy, thereby inhibiting UVB-mediated oxidative stress further reducing skin ageing. Q-switched 1064 nm Nd: YAG laser treatment inhibited UVB-induced oxidative stress and restored skin photoageing by activating autophagy, and TGFβ1 and ITGB1 directly incorporated and participated in this process.

Rad2, Rad14 and Rad26 recover Metarhizium robertsii from solar UV damage through photoreactivation in vivo

Rad2, Rad14 and Rad26 recover ultraviolet (UV) damage by nucleotide excision repair (NER) in budding yeast but their functions in filamentous fungi have not been elucidated. Here, we report mechanistically different anti-UV effects of nucleus-specific Rad2, Rad14 and Rad26 orthologs in Metarhizium robertsii, an insect-pathogenic fungus. The null mutants of rad2, rad14 and rad26 showed a decrease of ∼90% in conidial resistance to UVB irradiation. When conidia were impaired at a UVB dose of 0.15 J/cm2, they were photoreactivated (germinated) by only 6–13% through a 5-h light plus 19-h dark incubation, whereas 100%, 80% and 70% of the wild-type conidia were photoreactivated at 0.15, 0.3 and 0.4 J/cm2, respectively. The dose-dependent photoreactivation rates were far greater than the corresponding 24-h dark reactivation rates and were largely enhanced by the overexpression (OE) of rad2, rad14 or rad26 in the wild-type strain. The OE strains exhibited markedly greater activities in photoreactivation of conidia inactivated at 0.5–0.7 J/cm2 than did the wild-type strain. Confirmed interactions of Rad2, Rad14 and Rad26 with photolyase regulators and/or Rad1 or Rad10 suggest that each of these proteins could have evolved into a component of the photolyase regulator-cored protein complex to mediate photoreactivation. The interactions inhibited in the null mutants resulted in transcriptional abolishment or repression of those factors involved in the complex. In conclusion, the anti-UV effects of Rad2, Rad14 and Rad26 depend primarily on DNA photorepair-dependent photoreactivation in M. robertsii and mechanistically differ from those of yeast orthologs depending on NER.

Effect of Postharvest UVB Irradiation on the Fruit of cv. Dottato (Ficus carica L.)

Exposing fruits and vegetables to UVB radiation post-harvest is a technique used to modify secondary metabolites and prolong their shelf life. The aim of the present study was to evaluate the effects of UVB irradiation on the chemical and physical characteristics of fig cv. Dottato fruits. The UVB irradiation was 2.26 Wm−2. Two exposure times were carried out: 10 and 60 min resulting in a UVB dose of 1.4 and 8.1 kJm−2, respectively. In the control, the UVB was eliminated by a polyester film (control −UVB). After treatment, the fig fruits were stored and analyzed at different times until decay. Quality parameters (decay, weight loss, color, chlorophyll, and firmness) and physicochemical parameters (soluble solids content, pH parameters, and titratable acidity) were positively influenced by irradiation. Total and individual sugars increased gradually during the storage period in both the skin and the flesh, with glucose being higher after 10 days in the UVB treated samples. Total carotenoid content increased gradually during the storage period, with a marked increase in the +UVB fruit. The content of total and individual polyphenols was positively influenced by UVB treatment, with the UVB treated samples showing the highest values at both 7 and 10 days. The study showed an increase in by-products in both the skin and the flesh. This research confirms the effectiveness of UVB radiation in improving the nutritional qualities and shelf life of Ficus carica fruits.

Between eustress and distress: UVB induced changes in carotenoid accumulation in halophytic Salicornia europaea

Halophytes are potential future crops with a valuable nutritional profile. Produced in indoor farming, they are considered to contribute to sustainable and resilient food systems. Indoor farms operate using artificial light. In this context narrowband and low dose UVB radiation can be used to increase plant secondary metabolites, such as carotenoids, and provide an improved nutritional profile for a human diet. UVB radiation can cause eustress or distress in the plant depending on the lighting situation. The aim of this study was to identify the doses of UVB that lead to either eustress or distress and to analyze these responses in Salicornia europaea. Therefore, S. europaea plants were exposed to different UVB radiation levels, low, medium and high, and analyzed for reactive oxygen species (ROS), plant hormones, amino acids, and photosynthetic pigments. High UVB treatment was found to affect phenotype and growth, and the metabolite profile was affected in a UVB dose-dependent manner. Specifically, medium UVB radiation resulted in an increase in carotenoids, whereas high UVB resulted in a decrease. We also observed an altered oxidative stress status and increased SA and decreased ABA contents in response to UVB treatment. This was supported by the results of menadione treatment that induces oxidative stress in plants, which also indicated an altered oxidative stress status in combination with altered carotenoid content. Thus, we show that a moderate dose of UVB can increase the carotenoid content of S. europaea. Furthermore, the UVB stress-dependent response led to a better understanding of carotenoid accumulation upon UVB exposure, which can be used to improve lighting systems and in turn the nutritional profile of future crops in indoor farming.

Influence of chlorpyrifos exposure on UVB irradiation induced toxicity in human skin cells

BackgroundAlthough chlorpyrifos (CPS) has been banned in many developed countries, it still remains one of the best-selling pesticides in the world. Widespread environmental and occupational exposure to CPS pose a serious risk to human health. Another environmental factor that can adversely affect human health is ultraviolet radiation B (UVB, 280–315 nm wave length). Here we attempt determine if exposure to CPS can modify toxic effects of UVB. Such situation might be a common phenomenon in agriculture workers, where exposure to both factors takes place.MethodsTwo skin cell lines; namely human immortalized keratinocytes HaCaT and BJ human fibroblasts were used in this study. Cytotoxicity was investigated using a cell membrane damage detection assay (LDH Cytotoxicity Assay), a DNA damage detection assay (Comet Assay), an apoptosis induction detection assay (Apo-ONE Homogeneous Caspase-3/7 Assay) and a cell reactive oxygen species detection assay (ROS-Glo H2O2 assay). Cytokine IL-6 production was also measured in cells using an ELISA IL-6 Assay.ResultsPre-incubation of skin cells with CPS significantly increased UVB-induced toxicity at the highest UVB doses (15 and 20 mJ/cm2). Also pre-exposure of BJ cells to CPS significantly increased the level of DNA damage, except for 20 mJ/cm2 UVB. In contrast, pre-exposure of HaCaT cells, to CPS prior to UVB radiation did not cause any significant changes. A decrease in caspase 3/7 activity was observed in HaCaT cells pre-exposed to 250 µM CPS and 5 mJ/cm2 UVB. Meanwhile, no statistically significant changes were observed in fibroblasts. In HaCaT cells, pre-exposure to CPS resulted in a statistically significant increase in ROS production. Also, in BJ cells, similar results were obtained except for 20 mJ/cm2. Interestingly, CPS seems to inhibited IL-6 production in HaCaT and BJ cells exposed to UVB (in the case of HaCaT cells for all UVB doses, while for BJ cells only at 15 and 20 mJ/cm2).ConclusionsIn conclusion, the present study indicates that CPS may contribute to the increased UVB-induced toxicity in skin cells, which was likely due to the induction of ROS formation along with the generation of DNA damage. However, further studies are required to gain better understanding of the mechanisms involved.

Investigating physiological responses of Wild Rocket subjected to artificial Ultraviolet B irradiation

Utilization of ultraviolet-B radiation (UV-B) is a way to encourage the accumulation of phytochemicals such as glucosinolates, carotenoids, phenolics and flavonoids in plants. In the current research, UV-B treatments were performed, as a possible elicitation strategy to promote the secondary metabolites accumulation in wild rocket (Diplotaxis tenuifolia (L.) DC). After performing the destructive analysis, it has been found that the concentration of chlorophyl a and b as well as carotenoids decreased in response to the UV-B stress. Thiobarbituric acid reactive substances (TBARS) assay has been performed to investigate the membranes damage caused by the UV-B radiation. The analyses confirmed that the highest UV-B tested dose induced the greater damage. Interestingly, an increase of phenolic index, and an accumulation of anthocyanins and glucosinolates has been recorded under the successive exposure of varying UV-B doses. The total sugars, reducing sugars and sucrose buildup were also remarkable. Non-destructive analysis revealed a decline in the overall performance of the UV-B treated plants as well as the maximum quantum efficiency of photosystem II. A decrease in the chlorophyll estimates while an enhanced flavanols and anthocyanins were observed through non-destructive readings. Results of this study not only provided a feasible UV-B dose selection and supplementation for the wild rocket but also the understanding about enhanced phytochemical accumulation in plants against UV-B stress.

Ultraviolet-B radiation, mushrooms, and vitamin D: From technology to bioavailability

We describe an efficient technology to obtain vitamin D2-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 D2 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 D2 supplements from mushrooms. In addition, the same method increased the vitamin D2 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.