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At least 919 records · Page 51Linked to original sources
PubMed1981

Sterol Composition and Accumulation in Glycine max (L.) Merr Leaves under Different Filtered Sunlight Conditions.

Soybean plants (Merr) were grown in the field in three plots. Sixteen days after sowing, two plots were covered with blue and red polyvinylchloride filters (0.45 millimeter thick) and one remained uncovered as control. Leaves of all plots were analyzed for total, free, esterified, and glycosidic sterols at two successive stages of plant growth (flowering and podripening).During the growth, total sterols increased in the control sample and under red and blue polyvinylchloride filters. Although free sterol contents were always the highest, the esterified sterols were mainly responsible for this increase. Red and blue polyvinylchloride filters caused a general decrease in the amounts of sterol classes but, during the growth, they caused the largest and most consistent changes. These filters particularly increased sitosterol and decreased stigmasterol. The changes in relative amounts of stigmasterol and sitosterol in soybean leaves might represent an interconversion between these two sterols. There seems to be a general increase-decrease relationship due to light quality.

Journal Article↗
PubMed2006

Gene expression of Escherichia coli in continuous culture during adaptation to artificial sunlight.

Escherichia coli growing in continuous culture under continuous UVA irradiation exhibits growth inhibition with a subsequent adaptation to the stress. Transcriptome analysis was performed during transient growth inhibition and in the UVA light-adapted growth state. The results indicate that UVA light induces stringent response and an additional response that includes the upregulation of the synthesis of valine, isoleucine, leucine, phenylalanine, histidine and glutamate. The induction of several SOS response-genes strongly points to DNA damage as a result of UVA exposure. The involvement of oxidative stress was observed with the induction of ahpCF. Taken together it supports the hypothesis of the production of reactive oxygen species by UVA light. In the UVA-adapted cell population strong repression of the acid tolerance response was found. We identified the enzyme chorismate mutase as a possible chromophore for UVA light-inactivation and found strong repression of the pyrBI operon and the gene mgtA encoding for an ATP-dependent Mg2+ transporter. Furthermore, our results indicate that the role of RpoS may not be as important in the adaptation of E. coli to UVA light as it was implicated by previous results with starved cells, but that RpoS might be of crucial importance for the resistance under transient light exposure.

Adaptation, Physiological↗
PubMed1987

Sunscreens and their use in the preventive treatment of sunlight-induced skin damage.

In this brief review, clinically relevant practical aspects of topical protection against the harmful effects of solar radiation on human skin are discussed. The article covers information in the following areas of photo-protection: nature of solar radiation; classification of normal individuals into sun-reactive skin types I-VI; minimal erythema doses of UVB and UVA radiation for individuals of skin types I-VI; classification of sunscreens and SPF values of brand-name sunscreens; a list of UVB- and UVA-absorbing chemicals used in sunscreen formulations in the USA; guidelines for recommending topical sunscreens for the prevention of sunburn, skin photoaging, and skin cancer; and concerns about the harmful effects of UVA radiation and tanning parlors on human skin and the methods used to minimize the potential damaging effects of UVA.

Humans↗
PubMed2002

Insect cells and their potential as stabilization barriers for DNA of multiple and single nucleopolyhedroviruses against ultraviolet-B-simulated sunlight inactivation.

A cell line from Trichoplusia ni (TN-CL1) infected with the Autographa californica multiple nucleopolyhedrovirus (AcMNPV-HPP) and a cell line from Helicoverpa zea (BCIRL-HZ-AM1) infected with the Helicoverpa zea single nucleopolyhedrovirus (HzSNPV/BrCL2) were subjected to ultraviolet-B (UV-B) irradiation at a predetermined level of exposure that would inactivate greater than 95% of the virus suspended in the liquid. The working hypothesis was that the homologous insect cells would utilize their inherent deoxyribonucleic acid (DNA) repair mechanism(s) to prevent, repair, or at least mitigate the damaging effects of UV-B light on viral DNA synthesis. We attempted to determine this by using infected cells that were subjected to UV-B irradiation at different postinoculation periods under two experimental conditions of exposure: (1) shielded, and (2) nonshielded. Of the two cell lines infected with their respective homologous viruses, the virus from TN-CL1 cells was the least sensitive to UV-B light because the extracellular virus (ECV) and occlusion body (OB) levels of virus-infected TN-CL1 cells were higher than those of the virus-infected BCIRL-HZ-AM1 cells. Production of ECV and OB from both cell lines was lower in the exposed, nonshielded treatment than in the exposed, shielded treatment. However, AcMNPV-HPP was produced in enough quantity to indicate that TN-CL1 might impart a level of protection to the virus against UV light.

Animals↗