Effects Of ultraviolet-B Research Articles

Effect of Pre-Harvest Intermittent UV-B Exposure on Growth and Secondary Metabolites in Achyranthes japonica Nakai Microgreens in a Vertical Farm

Achyranthes japonica Nakai (AJN) is a medicinal plant known to be beneficial for the joints. Since it takes at least two years from sowing to harvesting in an open field, new AJN cultivation strategies are needed to shorten the production period and improve quality. In this study, high-quality AJN is produced as microgreens in a vertical farm using a commercial ginseng soil mix (Myeongpum-Insamsangto, Shinsung Mineral Co., Ltd., Goesan, Republic of Korea) and controlled environmental conditions. The cultivation conditions included a temperature of 23 ± 2 °C, relative humidity of 50 ± 10%, and a photosynthetic photon flux density of 170 ± 15 µmol·m−2·s−1. Pre-harvest intermittent UV-B exposure, with an intensity of 1.0 ± 0.3 W/m−2, was applied for one day before harvest to evaluate its effects, using controlled environmental conditions in the vertical farm. Ultraviolet-B (UV-B) irradiation increases secondary metabolite levels in plants; however, the effect of UV-B on 20-hydroxyecdysone (20E), an indicator of AJN, is unclear. Therefore, we aimed to investigate whether UV-B treatment of AJN microgreens affected growth and secondary metabolites. The treatment group was set to 12 h of continuous UV-B treatment during the day, two 6 h UV-B treatments, and four 3 h UV-B treatments to confirm the effectiveness of regular and intermittent treatment and recovery. Short-term UV-B treatment before harvesting increased phenols, flavonoids, antioxidant capacity, and 20E levels without affecting AJN biomass. The intermittent 6 h UV-B irradiation with a 6 h recovery time stimulated 20E content by approximately 1.4 times compared to the control. These study findings indicate that short-term UV-B treatment before harvesting, an appropriate recovery time, and intermittent UV-B exposure are more effective at increasing 20E content than continuous treatment. This approach provides a promising strategy for improving the nutritional and health benefits of AJN microgreens in vertical farming systems.

Effects of UV-B and UV-C Spectrum Supplementation on the Antioxidant Properties and Photosynthetic Activity of Lettuce Cultivars.

Indoor farming systems enable plant production in precisely controlled environments. However, implementing stable growth conditions and the absence of stress stimulants can weaken plants' defense responses and limit the accumulation of bioactive, health-beneficial phytochemicals. A potential solution is the controlled application of stressors, such as supplemental ultraviolet (UV) light. To this end, we analyzed the efficiency of short-term pre-harvest supplementation of the red-green-blue (RGB, LED) spectrum with ultraviolet B (UV-B) or C (UV-C) light to boost phytochemical synthesis. Additionally, given the biological harm of UV radiation due to high-energy photons, we monitored plants' photosynthetic activity during treatment and their morphology as well as sensory attributes after the treatment. Our analyses showed that UV-B radiation did not negatively impact photosynthetic activity while significantly increasing the overall antioxidant potential of lettuce through enhanced levels of secondary metabolites (total phenolics, flavonoids, anthocyanins), carotenoids, and ascorbic acid. On the contrary, UV-C radiation-induced anthocyanin accumulation in the green leaf cultivar significantly harmed the photosynthetic apparatus and limited plant growth. Taken together, we showed that short-term UV-B light supplementation is an efficient method for lettuce biofortification with healthy phytochemicals, while UV-C treatment is not recommended due to the negative impact on the quality (morphology, sensory properties) of the obtained leafy products. These results are crucial for understanding the potential of UV light supplementation for producing functional plants.

Annexin A1 protects epidermal stem cells against ultraviolet-B irradiation-induced mitochondrial dysfunction.

Ultraviolet-B (UV-B) radiation overexposure causes function impairment of epidermal stem cells (ESCs). We explored the mechanism of Annexin A1 (ANXA1) ameliorating UV-B-induced ESC mitochondrial dysfunction/cell injury. ESCs were cultured in vitro and irradiated with different doses of UV-B. Cell viability/ANXA1 protein level were assessed. After oe-ANXA1 transfection, ESCs were treated with oe-ANXA1/UV-B irradiation/CCCP/CCG-1423/3-methyladenine for 12h. Cell viability/death, and adenosine triphosphate (ATP)/reactive oxygen species (ROS) levels were determined. Mitochondrial membrane potential (MMP) changes/DNA (mtDNA) content/oxygen consumption and RhoA activation were assessed. ROCK1/p-MYPT1/MYPT1/(LC3BII/I)/Beclin-1/p62 protein levels were determined. Mitochondrial morphology was observed. Mito-Tracker Green (MTG) and LC3B levels were determined. UV-B irradiation decreased cell viability/ANXA1 expression in a dose-dependent manner. UV-B-treated ESCs exhibited reduced cell viability/ATP content/MMP level/mitochondrial respiratory control ratio/mtDNA number/RhoA activity/MYPT1 phosphorylation/MTG+LC3B+ cells/(LC3BII/I) and Beclin-1 proteins, increased cell death/ROS/p62/IL-1β/IL-6/TNF-α expression, contracted mitochondrial, disappeared mitochondrial cristae, and increased vacuolar mitochondria, which were averted by ANXA1 overexpression, suggesting that UV-B induced ESC mitochondrial dysfunction/cell injury/inflammation by repressing mitophagy, but ANXA1 promoted mitophagy by activating the RhoA/ROCK1 pathway, thus repressing UV-B's effects. Mitophagy activation ameliorated UV-B-caused ESC mitochondrial dysfunction/cell injury/inflammation. Mitophagy inhibition partly diminished ANXA1-ameliorated UV-B's effects. Conjointly, ANXA1 promoted mitophagy by activating the RhoA/ROCK1 pathway, thereby improving UV-B-induced ESC mitochondrial dysfunction/cell injury.

UVB radiation exposure modulates mitophagy in embryonic cells of freshwater prawn Macrobrachium olfersii: Exploring a protective organelle quality control mechanism

Aquatic environments are subject to ultraviolet B (UVB) radiation incidence, and its effects on organisms are dose-dependent. Besides DNA, mitochondria are an important target of this radiation that causes structural damage and impairs its functional dynamics. Here, we hypothesize that mitophagy acts as an organelle quality control mechanism to mitigate UVB impacts in embryonic cells. Then, freshwater prawn Macrobrachium olfersii embryos was used as a model to investigate the effects of UVB on genes (Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3) and proteins (TOM20, PINK1, p62 and LC3B) involved in mitophagy modulation. The choice of genes and proteins was based on the identification of mitochondrial membrane (Tomm20, Opa1 and TOM20), mediation of mitophagy (Pink1, Prkn and PINK1), and recognition of mitochondria by the autophagosome membrane (Sqstm1, Map1lc3, p62 and LC3B). First, the phylogeny of all genes presented bootstrap values >80 and conserved domains among crustacean species. Gene expression was inherently modulated during development, with transcripts (Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3) overexpressed in the initial and final stages of development. Moreover, UVB radiation induced upregulation of Tomm20, Opa1, Pink, Prkn, Sqstm1, and Map1lc3 genes at 6 h after exposure. Interestingly, after 12 h, the protein content of PINK1, p62, and LC3B increased, while TOM20 was not responsive. Despite UVB radiation's harmful effects on embryonic cells, the chronology of gene expression and protein content indicates rapid activation of mitophagy, serving as an organelle quality control mechanism, given the analyzed cells' integrity.

In Vitro Assessment of the Impact of Ultraviolet B Radiation on Oral Healthy and Tumor Cells

Ultraviolet radiation (UVR) is generally considered a primary tumorigenic agent. While UVR exposure has been studied, especially at the skin level, the impact of UV exposure on internal tissues and its effect on the appearance and the development of tumors has not yet been fully examined. Although there are maximum limits for UVR exposure on external tissues, other internal tissues, such as oral tissue, can be exposed to UVR as well. Over the course of diagnosis and treatment, oral cells may be exposed to ultraviolet radiation; however, there has not been an established limit for UV radiation exposure. Therefore, the aim of the current study was to examine the effects of ultraviolet-B (UVB) radiation at two doses (2.5 and 5 J/cm2) on tumor cells (pharyngeal carcinoma and tongue carcinoma) and healthy cells (gingival fibroblasts). The viability of the cells and their morphology, actin filaments, and nuclei structures; the expression of anti-apoptotic (Bcl-2) and pro-apoptotic (Bax) genes; and the roles of caspases-3/7, 8, and 9 were determined after the cells had been exposed to UVB. The experiments revealed that both types of cell lines showed reductions in viability, especially at a dose of 5 J/cm2. Additionally, apoptotic-like changes (rounding of the cells, the condensation of the nuclei, the re-organization of the actin filaments) were observed in all analyzed cells. The expression of anti-apoptotic (Bcl-2) and pro-apoptotic (Bax) genes revealed that UVB (5 J/cm2) may induce apoptosis in both oral tumor and healthy cells. Moreover, an analysis of caspases-3/7, 8, and 9 showed that UVB exposure enhanced their activity, suggesting that cell death could be caused by both intrinsic and extrinsic apoptosis. Accordingly, UVB exposure at the maximum doses used in dental practices (5 J/cm2) induced nonselective apoptotic changes, thereby reducing both tumor and healthy cell viability.

Effects of Short-Duration Artificial Ultraviolet B Exposure on 25-Hydroxyvitamin D3 Concentrations in Domestic Rabbits (Oryctolagus cuniculus).

Vitamin D is an important hormone that can be acquired through diet, exposure to ultraviolet B (UVB) radiation, or a combination of these methods. In domestic rabbits (Oryctolagus cuniculus), both methods appear viable, but there is limited research evaluating the effects of UVB on this species. Previous studies found that 12 h of artificial UVB radiation significantly increased 25-hydroxyvitamin D3 (25-OHD3) concentrations over time. While these findings suggest UVB can be beneficial in rabbits, this form of radiation can also be detrimental to vertebrates. The purpose of this study was to determine if shorter-duration UVB could elicit a similar physiological response in rabbits while minimizing potential negative effects. Six rabbits were used for this pilot study. The baseline serum 25-OHD3 was measured for each rabbit and following 14 days of 6 h/day exposure to artificial UVB, a second 25-OHD3 sample was collected. There was a significant increase (p = 0.001) in serum 25-OHD3 over time (Baseline: 27.7 ± 8.1 nmol/L; Day 14: 79.8 ± 9 nmol/L). This study affirmed that 6 h of UVB produced 25-OHD3 concentrations similar to those found in rabbits exposed to 12 h of UVB. Future studies should continue to determine how the duration of UVB exposure affects 25-OHD3 concentrations.

AtBBX29 integrates photomorphogenesis and defense responses in Arabidopsis

Light is an environmental signal that modulates plant defenses against attackers. Recent research has focused on the effects of light on defense hormone signaling; however, the connections between light signaling pathways and the biosynthesis of specialized metabolites involved in plant defense have been relatively unexplored. Here, we show that Arabidopsis BBX29, a protein that belongs to the B-Box transcription factor (TF) family, integrates photomorphogenic signaling with defense responses by promoting flavonoid, sinapate and glucosinolate accumulation in Arabidopsis leaves. AtBBX29 transcript levels were up regulated by light, through photoreceptor signaling pathways. Genetic evidence indicated that AtBBX29 up-regulates MYB12 gene expression, a TF known to induce genes related to flavonoid biosynthesis in a light-dependent manner, and MYB34 and MYB51, which encode TFs involved in the regulation of glucosinolate biosynthesis. Thus, bbx29 knockout mutants displayed low expression levels of key genes of the flavonoid biosynthetic pathway, and the opposite was true in BBX29 overexpression lines. In agreement with the transcriptomic data, bbx29 mutant plants accumulated lower levels of kaempferol glucosides, sinapoyl malate, indol-3-ylmethyl glucosinolate (I3M), 4-methylsulfinylbutyl glucosinolate (4MSOB) and 3-methylthiopropyl glucosinolate (3MSP) in rosette leaves compared to the wild-type, and showed increased susceptibility to the necrotrophic fungus Botrytis cinerea and to the herbivore Spodoptera frugiperda. In contrast, BBX29 overexpressing plants displayed increased resistance to both attackers. In addition, we found that AtBBX29 plays an important role in mediating the effects of ultraviolet-B (UV-B) radiation on plant defense against B. cinerea. Taken together, these results suggest that AtBBX29 orchestrates the accumulation of specific light-induced metabolites and regulates Arabidopsis resistance against pathogens and herbivores.Graphical

Preharvest UV-B Treatment Improves Strawberry Quality and Extends Shelf Life

Postharvest ultraviolet B (UV-B) radiation has been used to control pathogen incidence on fresh produce, but little attention has been paid to preharvest UV-B effect on strawberry fruit quality and storage. In this study, strawberry (Fragaria × ananassa Duch. cv Albion) plants grown in greenhouse were irradiated with UV-B lamps with an intensity of 0.7362 J/s m2 for 1 and 2 h every day from 5–7 pm after flowering. Fruits were harvested at red stage for quality evaluation. The results indicated that the preharvest UV-B-treated fruits had lighter color (increased L*) than the control. Total soluble solids (TSS), total phenolics content (TPS) and total anthocyanin content (TAC) of UV-B-treated fruits were higher than for the control fruits. There were no significant differences in any of the quality traits between UV-B one-hour and two-hour treatments. We further evaluated the fruit quality when stored at 5 °C on day 7 and day 14. Compared to untreated control, UV-B-treated fruits retarded decrease in L*, TSS, TPS, TAC and firmness, and reduced fruit decay. Examination of expression of genes related to UV-B signaling indicated that HY5 was the major component of UV-B signaling during the green and white stages. However, anthocyanin genes were highly responsive to UV-B treatment during the red stage. Our results suggest that utilization of a low dose of UV-B radiation during the growth stage can improve strawberry fruit quality, and extend shelf life. This research facilitates the utilization of preharvest UV-B treatment for improving fruit quality in controlled environment agriculture.

Продукция активных форм кислорода при действии ультрафиолетового-В излучения на клетки дрожжей

The present investigation is devoted to the study of the effect of ultraviolet-B (UV-B) radiation on the survival and production of reactive oxygen species in yeast cells. It has been determined that under the action of UV-B radiation on cells, depending on its dose, the rate of oxidation of the dye 2',7'-dichlorodihydrofluorescein diacetate (H2DCF•DA) increases and a high intensity of DCF fluorescence is observed. When cells are modified with ascorbic acid before irradiation, the rate of H2DCF oxidation and the intensity of DCF fluorescence decreases. The survival rate of modified cells is increased. Ascorbic acid reduces the amount of ROS in the suspension of irradiated cells. At high doses (4.5-10 erg/mm2) of irradiation, the antioxidant effect of ascorbic acid in yeast cells is negligible. The concentration of 2-4 dinitrophenol (DNF) 10-7 M was determined as a protector, in which the substance potentially contributes to the manifestation of the effect of "soft uncoupling" in cells and, under the influence of UV-B radiation on yeast cells, helps to reduce the production of reactive oxygen species and an increase in survival. High concentrations (10–3M–10–5 M) of DNP adversely affect the survival of yeast cells and ROS production. So, it can be concluded that under the action of UV-B rays on yeast cells, antioxidants can possibly participate in the regulation of redox homeostasis.

Dual effect of ultraviolet B on cholesterol efflux and regulated by ultraviolet radiation resistance-associated gene-mediated autophagy.

In addition to diet and metabolism, the occurrence of foam cells and atherosclerosis are also related to environmental factors. Individual studies have shown that ultraviolet B (UVB) can regulate the progression of atherosclerosis, but with different results. Whether or not UVB has a dual effect on atherosclerosis and what mechanism is involved has not been reported. After THP-1-derived foam cells were treated with UVB in different ways, the effects of UVB on foam cells were investigated by western blotting, cholesterol efflux experiment, oil red O staining and other methods. UVB plays a dual role on foam cell formation, and this effect is related to cholesterol efflux. UVB of 50mJ/cm2 can promote cholesterol efflux in foam cells, while UVB of 200mJ/cm2 can inhibit cholesterol efflux. UVB induces cholesterol efflux from foam cells in an autophagy-dependent manner, as the beneficial effect of UVB at 50mJ/cm2 can be reversed by the autophagy inhibitor 3-Methyladenine (3-MA). In addition, silencing the expression of ultraviolet radiation resistance-associated gene (UVRAG) can inhibit autophagy and reduce cholesterol efflux, and overexpressing UVRAG yields the opposite result. In conclusion, our research proves that UVB exhibits a dual role in foam cell formation by regulating cholesterol efflux. Further more, we also reveal that UVRAG-mediated autophagy is the underlying mechanism of UVB-induced cholesterol efflux.

Proteomic analysis response of rice (Oryza sativa) leaves to ultraviolet-B radiation stress.

Rice (Oryza sativa) is a human staple food and serves as a model organism for genetic and molecular studies. Few studies have been conducted to determine the effects of ultraviolet-B (UV-B) stress on rice. UV-B stress triggers morphological and physiological changes in plants. However, the underlying mechanisms governing these integrated responses are unknown. In this study, we conducted a proteomic response of rice leaves to UV-B stress using two-dimensional gel electrophoresis and identified the selected proteins by mass spectrometry analysis. Four levels of daily biologically effective UV-B radiation intensities were imposed to determine changes in protein accumulation in response to UV-B stress: 0 (control), 5, 10, and 15 kJ m−2 d−1in two cultivars, i.e., IR6 and REX. To mimic the natural environment, we conducted this experiment in Sunlit Soil-Plant-Atmosphere-Research (SPAR) chambers. Among the identified proteins, 11% of differentially expressed proteins were found in both cultivars. In the Rex cultivar, only 45% of proteins are differentially expressed, while only 27.5% were expressed in IR6. The results indicate that REX is more affected by UV-B stress than IR6 cultivars. The identified protein TSJT1 (spot 16) in both cultivars plays a crucial role in plant growth and development during stress treatment. Additionally, we found that UV-B stress altered many antioxidant enzymes associated with redox homeostasis and cell defense response. Another enzyme, the glyceraldehyde-3-phosphate dehydrogenase (GAPDH), has been identified as spot 15, which plays an essential role in glycolysis and cellular energy production. Another vital protein identified is glycosyl hydrolase (GH) as spot 9, which catalyzes the hydrolysis of glycosidic bonds in cell wall polymers and significantly affects cell wall architecture. Some identified proteins are related to photosynthesis, protein biosynthesis, signal transduction, and stress response. The findings of our study provide new insights into understanding how rice plants are tailored to UV-B stress via modulating the expression of UV-B responsive proteins, which will help develop superior rice breeds in the future to combat UV-B stress. Data are available via ProteomeXchange with identifier PXD032163.

Comparison of the suppressive effect on the two-spotted spider mite <i>Tetran</i><i>ychus urticae</i> Koch among different installation methods of light-reflection materials in a strawberry greenhouse using ultraviolet-B lamps and phytoseiid mites

Artificial ultraviolet-B (UV-B) radiation is lethal to the two-spotted spider mite Tetranychus urticae. Recent studies in greenhouse strawberry have shown that light-reflecting sheets installed under strawberry plants can increase the suppressive effect of UV-B on T. urticae by reflecting the UV-B delivered from overhead lamps to the underside of the leaves. These methods are expected to be complementary to biological control methods, such as phytoseiid mites. However, light-reflecting sheets have low water permeability, which can result in the formation of puddles after pesticide spraying, leading to fruit deterioration and loss of yield. It is important to explore highly efficient installation methods for light-reflecting materials (LRMs) in spider mite control. Here, we examined the effects of three LRMs, and the impact of LRM orientation (horizontal vs. vertical), on T. urticae populations in greenhouse strawberry treated with UV-B radiation, chemical pesticides, and biopesticide control with phytoseiid mites. Of the three LRMs examined, a reflective 0.6 × 0.6-mm-mesh polyethylene net (“Mushi Furatto Net”) and a 2.0 × 7.0-mm-mesh polyethylene net woven with flashspun nonwoven fabric sheets (“Slimwhite 75”) offered significantly increased suppression of T. urticae populations compared with white mulching sheet alone. Even though these LRMs were installed horizontally, they were little stained at the end of the experiment, suggesting that puddle formation after pesticide spraying was avoided.

Evolution of Physicochemical Properties, Phenolic Acid Accumulation, and Dough-Making Quality of Whole Wheat Flour During Germination Under UV-B Radiation.

The effects of ultraviolet-B (UV-B) radiation on the physiological properties, phenolic acid accumulation, and dough-making quality of wheat during germination were investigated. UV-B radiation inhibited the wheat sprout length and reduced the dry matter loss. As phenolic acids were principally present in the kernels' bran, UV-B radiation could promote their accumulation in the interior of germinated wheat (GW). The total phenolic compounds, ascorbic acid, and antioxidant activity were also enhanced significantly during germination with UV-B. UV-B improved the development time, stability time, rheological properties, and viscosity of GW, and inhibited the α-amylase activity, the destruction of the amorphous region of starch particles, and the proteins degradation process during germination, and thus the deterioration of dough-making quality caused by germination was inhibited. Therefore, UV-B radiation could be a potential approach to enhance the nutritional and dough-making quality of germinated whole wheat flour.

Ultraviolet B Irradiation Alters the Level and miR Contents of Exosomes Released by Keratinocytes in Diabetic Condition.

Ultraviolet B (UVB) stimulates the generation of extracellular vesicles, which elicit systemic effects. Here, we studied whether UVB affects the release and microRNA (miR) content of keratinocyte exosomes (EXs) in diabetic conditions. In vitro, we examined the UVB effects on affecting EX release from keratinocyte HaCaT cells (HaCaT‐EX) pretreated with high glucose. HaCaT‐EX functions were evaluated on Schwann cells (SCs). In vivo, UVB‐induced miR change in skin EXs of diabetic db/db mice was analyzed. The miRs of interest were validated in HaCaT‐EXs. We found that: (1) UVB promoted HaCaT‐EX generation in dose‐ and time‐dependent manners; 100 and 1800 J m−2 of UVB had the most prominent effect and were selected as effective low‐ and high‐fluence UVB in vitro. (2) A total of 13 miRs were differentially expressed >3‐fold in skin EXs in UVB‐treated db/db mice; miR‐126 was the most up‐regulated by low‐fluence UVB. (3) Functional studies revealed that the SC viability was improved by low‐fluence UVB HaCaT‐EXs, while worsened by high‐fluence UVB HaCaT‐EXs. (4) MiR‐126 inhibitor attenuated the effects induced by low‐fluence UVB HaCaT‐EXs. Our data have demonstrated that low‐ and high‐fluence UVBs promote HaCaT‐EX generation but differentially affect exosomal miR levels and functions under diabetic conditions.

Weak UVB Irradiation Promotes Macrophage M2 Polarization and Stabilizes Atherosclerosis

Atherosclerosis (AS) is a chronic cardiovascular disease endangering human health and is one of the most common causes of myocardial infarction and stroke. Macrophage polarization plays a vital role in regulating plaque stability. As an important component of sunlight, ultraviolet B (UVB) has been proven to promote vitamin D and nitric oxide synthesis. This research used an AS model in ApoE−/− mice to study the effects of UVB on macrophage polarization and atherosclerotic plaque stability. In vitro, UVB irradiation increased arginase-I (Arg-I, M2 macrophage) and macrophage mannose receptor (CD206) expression, while the expression of inducible nitric oxide synthase (iNOS) (M1 macrophage) and CD86 was decreased. UVB promoted Akt phosphorylation in vitro. In vivo, UVB irradiation promoted the stabilization of atherosclerotic lesion plaques, while the phenotype of M2 macrophages increased. Our research provides new evidence for UVB in preventing and treating atherosclerosis.

Solar UV-B effects on composition and UV screening efficiency of foliar phenolics in Arabidopsis thaliana are augmented by temperature.

The accumulation of foliar phenolics constitutes one strategy of plants against the potentially harmful effects of ultraviolet-B and A (UV-B, UV-A) radiation. These compounds protect photosensitive tissues by shielding and antioxidative function. It is unknown, however, whether seasonal acclimation to natural conditions may modify the UV-B effect on phenylpropanoid composition and localisation, and thus their screening efficiency. To address this debate, a field experiment with the wildtype of Arabidopsis thaliana accession Landsberg erecta (Ler) was implemented over a whole year with plants exposed to different UV-filter treatments. While seasonal increases of UV-B radiation had a slight negative effect on the amount of hydroxycinnamic acids (HCAs), low temperatures increased foliar HCAs. HCAs, however, did not contribute substantially to seasonal changes of in vivo UV absorbance. Kaempferol and quercetin derivatives increased significantly under ambient UV-B radiation, and low temperature interacted with this effect. A shift of epidermal UV-A shielding from kaempferol to quercetin derivatives was elucidated in UV-B presence. Despite this, a substantial 20-fold increase of quercetin derivatives, during periods with high irradiance and low temperature, did not affect UV absorbance leading to the conclusion that quercetin accumulation was not exclusively in epidermal vacuoles. Using confocal microscopy, the potential occurrence of quercetin in mesophyll cells was demonstrated in plants grown with experimental UV-B radiation at low temperature for the first time in A. thaliana. The presented study discusses the idea that cross-talk of UV-B radiation and temperature might adjust the physiological function of quercetin from an (epidermal) screening to an antioxidant substance.

Ultraviolet-B irradiance and cumulative dose combine to determine performance and survival.

Despite decades of research, the role of elevated solar ultraviolet-B radiation (UVBR; 280-315nm) in shaping amphibian populations remains ambiguous. These difficulties stem partly from a poor understanding of which parameters of UVBR exposure - dose, irradiance, and time interval - determine UVBR exposure health risk, and the potentially erroneous assumption that effects are proportional to the dose of exposure, irrespective of the administered regime (Bunsen-Roscoe Law of Reciprocity; BRL). We tested if the BRL holds with respect to UVBR-induced physiological effects in amphibians by acutely exposing tadpoles of the Australian green tree frog (Litoria caerulea) to a combination of different UVBR irradiances and doses in a fully factorial experiment. The BRL was invalid across all metrics assessed, with UVBR irradiance influencing the effects of a given dose on growth, coloration and burst swimming performance of larvae. We demonstrated some of the first empirical evidence for beneficial physiological effects of UVBR exposure in a larval amphibian, with improvements in growth, burst swimming performance and survival at the highest UVBR doses, contrary to hypotheses. Our findings demonstrate the species-specific nature of amphibian responses to UVBR, and the importance of UVBR irradiance in influencing the long-term physiological effects of a given dose of radiation. This work enhances our understanding of which parameters of complex UVBR exposures determine amphibian health risk.

Postharvest UV-B radiation increases enzyme activity, polysaccharide and secondary metabolites in honeysuckle (Lonicera japonica Thunb.)

Postharvest ultraviolet-B (UV-B) radiation can modulate the accumulation of bioactive compounds with many pharmacological effects in plants. Honeysuckle (Lonicera japonica Thunb.) is a UV-B tolerant crop which has a high medical value. The effects of UV-B on bioactive compounds in its flowers have been reported, while very few studies focused on the leaves and stems. Therefore, the effects of postharvest UV-B radiation on basic physiological traits and bioactive compounds (polysaccharides and secondary metabolites) in the leaves, stems and flowers of honeysuckle were investigated in this study. In this study, the leaves, stems and flowers of honeysuckle were exposed to UV-B radiation (0, 8.4 and 22.4 μW cm−2) for different times (2, 4, 6 and 8 h), and variables were detected after 24 h after they were able to get a repair time. The results showed that the contents of chlorophyll, carotenoid, soluble sugar, and the activities of catalase (CAT) and superoxide dismutase (SOD) in postharvest leaves were increased after UV-B treatment. But the malonaldehyde (MDA) content in leaves decreased when the duration of UV-B treatment lasted for 4 h. Besides, the contents of polysaccharide, total polyphenols, total flavonoid, and chlorogenic acid in different organs all increased significantly and reached a peak under the UV-B1 (8.4μW cm−2) treatment for 2 h, whereas they reached the lowest point under the 6 h of UV-B2 (22.4μW cm−2) exposure according to the heat map analysis. Interestingly, the Pearson correlation analysis revealed that the total flavonoid content was positively correlated with the chlorogenic acid content in the flowers of honeysuckle, and the total flavonoid content was negatively correlated with the contents of chlorophyll, CAT and carotenoid in plant leaves. In a word, the secondary metabolites and polysaccharide of honeysuckle can be increased by postharvest UV-B, and the quality can be improved by adjusting its physiological traits. In addition, the content of bioactive substances is correlated with the physiological traits. The results will provide a basis for improving the medicinal values of honeysuckle by postharvest UV-B treatment.

Conjunctival Expression of Toll-Like Receptor 3 Plays a Pathogenic Role in the Formation of Ultraviolet Light-Induced Pterygium.

PurposeToll-like receptor 3 (TLR3), as a damage-associated molecular pattern sensor, can detect self-RNA released from necrotic cells induced by ultraviolet B (UVB) radiation exposure. Pterygium formation is believed to be a tumorigenesis-like process induced by UVB exposure. In this study, we aimed to investigate the expression pattern of TLR3 in pterygium specimens and cultured pterygial epithelial cells (PECs).MethodsHuman pterygium and ipsilateral pterygium-free conjunctiva from the same patients were used in this study. The expression of TLR3 and nuclear factor-kappa B (NF-κB) was investigated in these specimens. PECs were exposed to UVB radiation to determine the effect of UVB on the expression of TLR3 and the activation of NF-κB.ResultsThe immunofluorescence study showed stronger TLR3 expression in superficial epithelial cells in the pterygial epithelium in comparison with the normal conjunctival epithelium. The expression of TLR3 decreased in intensity from the superficial epithelium toward the basal cell layer, implying a correlation between UVB exposure and TLR3 expression. Differential TLR3 expression patterns in pterygial and conjunctival tissues were also found in quantitative PCR analyses. PECs after UVB irradiation had higher protein levels of TLR3 and phospho-NF-κB than those of the PECs without irradiation. Immunofluorescence studies showed that UVB irradiation induced the nuclear translocation of NF-κB in the PECs. In PECs with the targeted TLR3 gene silencing, the expression of phospho-NF-κB was not induced by UVB irradiation.ConclusionsOur results indicate that UVB exposure, TLR3 expression, and NF-κB activation may be a critical sequence that leads to the formation of pterygium.

Skin exposure to UVB light induces a skin-brain-gonad axis and sexual behavior.

SummaryUltraviolet (UV) light affects endocrinological and behavioral aspects of sexuality via an unknown mechanism. Here we discover that ultraviolet B (UVB) exposure enhances the levels of sex-steroid hormones and sexual behavior, which are mediated by the skin. In female mice, UVB exposure increases hypothalamus-pituitary-gonadal axis hormone levels, resulting in larger ovaries; extends estrus days; and increases anti-Mullerian hormone (AMH) expression. UVB exposure also enhances the sexual responsiveness and attractiveness of females and male-female interactions. Conditional knockout of p53 specifically in skin keratinocytes abolishes the effects of UVB. Thus, UVB triggers a skin-brain-gonadal axis through skin p53 activation. In humans, solar exposure enhances romantic passion in both genders and aggressiveness in men, as seen in analysis of individual questionaries, and positively correlates with testosterone level. Our findings suggest opportunities for treatment of sex-steroid-related dysfunctions.