Effects Of ultraviolet-B Exposure Research Articles

Exposure to artificial ultraviolet-B light mediates alterations on the hepatic transcriptome and vitamin D metabolism in pigs

In the currently prevailing pig husbandry systems, the vitamin D status is almost exclusively dependent on dietary supply. Additional endogenous vitamin D production after exposure to ultraviolet-B (UVB) light might allow the animals to utilize minerals in a more efficient manner, as well as enable the production of functional vitamin D-enriched meat for human consumption. In this study, growing pigs (n = 16) were subjected to a control group or to a daily narrowband UVB exposure of 1 standard erythema dose (SED) for a period of 9 weeks until slaughter at a body weight of 105 kg. Transcriptomic profiling of liver with emphasis on the associated effects on vitamin D metabolism due to UVB exposure were evaluated via RNA sequencing. Serum was analyzed for vitamin D status and health parameters such as minerals and biochemical markers. The serum concentration of calcidiol, but not calcitriol, was significantly elevated in response to UVB exposure after 17 days on trial. No effects of UVB exposure were observed on growth performance and blood test results. At slaughter, the RNA sequencing analyses following daily UVB exposure revealed 703 differentially expressed genes (DEGs) in liver tissue (adjusted p-value < 0.01). Results showed that molecular pathways for vitamin D synthesis (CYP2R1) rather than cholesterol synthesis (DHCR7) were preferentially initiated in liver. Gene enrichment (p < 0.05) was observed for reduced cholesterol/steroid biosynthesis, SNARE interactions in vesicular transport, and CDC42 signaling. Taken together, dietary vitamin D supply can be complemented via endogenous production after UVB exposure in pig husbandry, which could be considered in the development of functional foods.

Responses of plants in polar regions to UVB exposure: a meta‐analysis

AbstractWe report a meta‐analysis of data from 34 field studies into the effects of ultraviolet B (UVB) radiation on Arctic and Antarctic bryophytes and angiosperms. The studies measured plant responses to decreases in UVB radiation under screens, natural fluctuations in UVB irradiance or increases in UVB radiation applied from fluorescent UV lamps. Exposure to UVB radiation was found to increase the concentrations of UVB absorbing compounds in leaves or thalli by 7% and 25% (expressed on a mass or area basis, respectively). UVB exposure also reduced aboveground biomass and plant height by 15% and 10%, respectively, and increased DNA damage by 90%. No effects of UVB exposure were found on carotenoid or chlorophyll concentrations, net photosynthesis, Fv/Fm or ΦPSII, belowground or total biomass, leaf mass, leaf area or specific leaf area (SLA). The methodology adopted influenced the concentration of UVB absorbing compounds, with screens and natural fluctuations promoting significant changes in the concentrations of these pigments, but lamps failing to elicit a response. Greater reductions in leaf area and SLA, and greater increases in concentrations of carotenoids, were found in experiments based in Antarctica than in those in the Arctic. Bryophytes typically responded in the same way as angiosperms to UVB exposure. Regression analyses indicated that the percentage difference in UVB dose between treatment and control plots was positively associated with concentrations of UVB absorbing compounds and carotenoids, and negatively so with aboveground biomass and leaf area. We conclude that, despite being dominated by bryophytes, the vegetation of polar regions responds to UVB exposure in a similar way to higher plant‐dominated vegetation at lower latitudes. In broad terms, the exposure of plants in these regions to UVB radiation elicits the synthesis of UVB absorbing compounds, reduces aboveground biomass and height, and increases DNA damage.

Effect of Combined Topical Glucocorticoids and Ultraviolet B Irradiation on Epidermal Langerhans Cells

The combined effect of topical glucocorticoids and ultraviolet B (UVB) irradiation on ATPase+ epidermal Langerhans cells in vivo was investigated in the guinea pig model. Glucocorticoids did not significantly enhance the response to UVB radiation, in the dosage range from 90-550 mJ/cm2 of UVB, suggesting that both agents were acting in a similar fashion. The solvent ethanol, however, potentiated the effect of UVB exposure due, at least in part, to increased penetration of the UVB into the epidermis. The recovery of ATPase+ Langerhans cells was significantly slower after high (greater than 165 mJ/cm2) than after more moderate doses (90-145 mJ/cm2) of UVB radiation.