bluuebunny/crossref_metadata_2025_split huggingface dataset:
UV radiation effects on pathogens and insect pests of greenhouse‐grown crops
Authors: Raviv Michael , Antignus Yehezkel 
Published: July 2010

AbstractProduction of high‐value crops is often performed under protected cultivation. In recent years various spectral modifications have been made in greenhouse covers. Two of the main reasons to modify the spectral characteristics of greenhouse covers have been to suppress the proliferation of several foliar diseases and to protect crops from insects and insect‐borne virus diseases of greenhouse‐grown crops. These goals were achieved by complete or partial absorption of solar UV radiation, which interrupts the life cycle of several fungal pathogens and alters the visual behavior of many insects. Examples of these management strategies are described in this article.
Photophysical and photobiological behaviour of antimalarial drugs in aqueous solutions
Authors: Aloisi Gian Gaetano , Barbafina Arianna , Canton Marcella , Dall'Acqua Francesco , Elisei Fausto , Facciolo Laura , Latterini Loredana , Viola Giampietro 
Published: July 2010

AbstractThis article describes the results of a combined photophysical and photobiological study aimed at understanding the phototoxicity mechanism of the antimalarial drugs quinine (Q), quinacrine (QC) and mefloquine (MQ). Photophysical experiments were carried out in aqueous solutions by stationary and time‐resolved fluorimetry and by laser flash pbotolysis to obtain information on the various decay pathways of the excited states of the drugs and on transient species formed on irradiation. The results obtained showed that fluorescence and intersystem crossing account for all the adsorbed quanta for Q and MQ (quantum yield of about 0.1 and 0.9, respectively) and only for 24% in the case of QC, which has a negligible fluorescence quantum yield (0.001). Laser flash photolysis experiments evidenced, for QC and, MQ, the occurrence of photoionization processes leading to the formation of the radical cations of the drugs. The effects of tryptophan and histidine on the excited states and transient species of the three drugs were also investigated. In parallel, the photoactivity of the antimalarial drugs was investigated under UV irradiation on various biological targets through a series ofin vitroassays in the presence and in the absence of oxygen. Phototoxicity on 3T3 cultured fibroblasts and lipid photoperoxidation were observed for all the drugs. The photodamage produced by the drugs was also evaluated on proteins by measuring the photosensitized cross‐linking of spectrin. The combined approaches were proven to be usefulfor understanding the mechanism of phototoxicity induced by the antimalarial drugs.
Changes in matrix gene and protein expressions after single or repeated exposure to one minimal erythemal dose of solar‐simulated radiation in human skin in vivo
Authors: Seité Sophie , Colige Alain , Deroanne Christophe , Lambert Charles , Piquemal‐Vivenot Pascale , Montastier Christiane , Fourtanier Anny , Lapière Charles , Nusgens Betty 
Published: July 2010

ASTRACTDamage to the skin extracellular matrix (ECM) is the hallmark of long‐term exposure to solar UV radiation. The aim of our study was to investigate the changes induced in unexposed human skin in vivo after single or repeated (five times a week for 6 weeks) exposure to 1 minimal erythemal dose (MED) of UV solar‐simulated rediation. Morphological and iochemical analyses were used to evaluate the stuctural ECM components and the balance between teh degrading enzymes the their physiologic inhibitors. a three‐fold increse in matrix metalloproteinase 2 messenger RNA (mRNA) (P < 0.02, unexposed versus exposed) was observed after both single and repeated exposures. Fibrillin 1 mRNA level was incresed by chronic exposure (P <0.02) and unaltered y a single MED. On the cotrary, a single MED singnificantly enhanced mRNA levels of interleukin‐1α (1L‐1α), IL‐1β (P < 0.02) and plasminogen activator inhibitor‐1 (P < 0.05). Immkunohistochemistry demonstrated a singnificant decrese in Type‐I procollagen localized just below the dermal‐epidermal junction in both types of expozed sites. at the same location, teh immunodetected tenascin was singnificantly enhanced, whereas a slight increase in Type‐III procollagen deposits was also unale to observe any change in elastic iers in chronically exposed uttock skin, a significant increase in lysozyme and alpha‐1 antitrypsin deposits on these fibers was oserved. These results demonstrate the existence of diffenentaia regulation, after chronic exposure compared with an acute one, of some ECM components and inflammatory mediators.
Matrix Metalloproteinase‐1 Production Observed After Solar‐Simulated Radiation Exposure is Assumed by Dermal Fibroblasts but Involves a Paracrine Activation Through Epidermal Keratinocytes¶
Authors: Fagot Dominique , Asselineau Daniel , Bernerd Françoise 
Published: July 2010

ABSTRACTChronic exposure of human skin to solar UV radiation leads to serious dermal damages, a hallmark of photoaging. In vivo, acute UV radiation has been shown previously to induce various matrix‐degrading proteases. Among them, matrix metalloproteinase‐1 (MMP‐1) has been suggested to be involved in skin photodamage. The purpose of this study was to investigate the effects of solar‐simulated radiation (SSR) on MMP‐1 production in normal human skin cells. SSR exposure of human skin reconstructed in vitro comprising both a differentiated epidermis and a fibroblast‐populated dermal equivalent led to an increase in MMP‐1 production, which was abolished when epidermis was removed immediately after SSR exposure. In addition, SSR exposure of differentiated keratinocytes grown on an acellular collagen gel did not induce MMP‐1 production. Experiments on cell cultures grown on plastic confirmed that keratinocytes failed, in contrast with fibroblasts, to produce MMP‐1 in response to SSR exposure. However, when conditioned medium from SSR‐exposed keratinocytes was added to human fibroblasts in culture, MMP‐1 production was induced. Altogether, these data show that MMP‐1 production observed after SSR exposure involved the release of soluble epidermal factors, which could modulate its production by dermal fibroblasts.
Photovoltaic Effects in Hornets Are Correlated with the Time of Day¶
Authors: Sverdlov Anna , Ishay Jacob S. 
Published: July 2010

ABSTRACTThis study deals with voltage values recorded off the cuticle of live specimens of the Oriental hornet Vespa orientalis (Hymenoptera, Vespidae). The relevant measurements were taken between the two tip of their bodies at various hours of the day and were made on a total of 90 worker hornets. Recorded voltage values varied within a range of 60‐180 mV, with the lower values measured during the morning hours and the afternoon and the highest values during the noon hours. Measurements were made by direct contact of the electrodes with the hornet cuticle and did not prove lethal to the measured specimens. An additional 60 live hornets were measured in the same fashion but in the dark. The values recorded in the dark varied between 40 and 70 mV and displayed considerable fluctuations but were not found to be dependent on the time of measurement. The distribution of the voltage values in hornets measured at various hours in the daytime closely resembled that of the global radiations (in W/m2) on the same days the measurements were taken.
A Monochromatic Action Spectrum for the Photoinduction of the UV‐Absorbing Mycosporine‐like Amino Acid Shinorine in the Red Alga chondrus crispus¶
Authors: Kräbs Gudrun , Watanabe Masakatsu , Wlencke Christian 
Published: July 2010

ABSTRACTTo determine the action spectrum for photoinduction of the ultraviolet (UV)‐absorbing mycosporine‐like amino acid shinorine, specimens of the marine red alga Chondrus crispus were irradiated with monochromatic light of various wavelengths using the Okazaki large spectrograph at the National Institute for Basic Biology, Okazaki, Japan. Fluence response curves were determined for the wavelengths between 280 and 750 nm, by irradiating the algae with monochromatic light for 10 h, followed by 4 h of 25 μmol m−2 s−1 photosynthetically active radiation and 10 h darkness. Samples were taken after the second exposure interval. A linear correlation between fluence rate and accumulated shinorine concentration was detected for wavelengths between 350 and 490 nm in the fluence rate range of 20–30 μmol m−2 s−1, whereas there was no induction above 490 nm. Below 350 nm a decline in shinorine concentration could be observed at fluence rates above 30 μmol m−2 s−1, probably due to an inhibition of photosynthetic activity and a subsequent impairment of shinorine biosynthesis. The constructed action spectrum indicated that the photoreceptors mediating shinorine photoinduction might be an unidentified UV‐A‐type photoreceptor with absorption peaks at 320, 340 and 400 nm.
Involvement of Cyanobacterial Phytochromes in Growth Under Different Light Qualitities and Quantities¶
Authors: Fledler Brita , Broc David , Schubert Hendrik , Rediger Anne , Börner Thomas , Wilde Annegret 
Published: July 2010

ABSTRACTInactivation of the genes for the cyanobacterial phytochromes cph1 and cph2 in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 affected the growth of the cells under certain light conditions. Differences in growth were detected by recording growth curves and in competition experiments. Mutation of cph1 and cph2 resulted in different effects. The cph1− mutant strains exhibited a reduced growth rate under far‐red light (FRL), whereas the growth of the cph2− mutant strains was inhibited by red light (RL). The growth rate of a cphl−/cph2− double mutant was reduced under both RL and FRL. Furthermore, cph1−, cph2− as well as double‐mutant strains showed impaired growth under high‐light (HL) conditions. Acclimation of the photosynthetic apparatus of the mutants to RL, FRL and HL, as determined by pigment analysis, was similar to that of the wild type.
Molecular Contrast Optical Coherence Tomography: A Review¶
Authors: Yang Changhuei 
Published: July 2010

ABSTRACTThis article reviews the current state of research on the use of molecular contrast agents in optical coherence tomography (OCT) imaging techniques. After a brief discussion of the basic principle of OCT and the importance of incorporating molecular contrast agent usage into this imaging modality, we shall present an overview of the different molecular contrast OCT (MCOCT) methods that have been developed thus far. We will then discuss several important practical issues that define the possible range of contrast agent choice, the design criteria for engineered molecular contrast agent and the implementability of a given MCOCT method for clinical or biological applications. We will conclude by outlining a few areas of pursuit that deserve a greater degree of research and development.
Two‐photon Excitation Induced Fluorescence of a Trifluorophore‐labeled DNA¶
Authors: Jockusch Steffen , Li Zengmin , Ju Jingyue , Turro Nicholas J. 
Published: July 2010

ABSTRACTTwo‐photon excitation of a trifluorophore (6‐carboxyfluorescein, N, N, N′, N′‐tetramethyl‐6‐carboxyrhodamine and cyamine‐5 monofunctional dye) labeled DNA, which has a scaffold of 26 nucleotides, was achieved using focused laser light of a Q‐switched Nd‐YAG laser (1064 nm). The observed fluorescence signature (emission ratio from the three fluorophores) of the labeled DNA after two‐photon excitation is very different from the fluorescence signatures produced by one‐photon excitation at different wavelenght. The additional fluorescence signatures produced by two‐photon excitation of the fluorescent oligonucleotides will facilitate their use as combinatorial fluorescence energy transfer tags for multiplex genetic analysis.
Photochemistry and Phototoxicity of Fluocinolone 16,17‐Acetonide¶
Authors: Miolo Giorgia , Caffieri Sergio , Daizoppo Daniele , Ricci Andrea , Fasani Elisa , Albini Angelo 
Published: July 2010

ABSTRACTFluocinolone 16,17‐acetonide is a corticosteroid used topically to treat various inflammatory skin diseases. Its photoreactivity was studied under UV‐A and UV‐B light in aqueous buffer in the presence of oxygen. This drug is photolabile under UV‐B light and, to a lesser extent, under UV‐A light, which is absorbed far less. In phosphate buffer, approximately 80% of fluocinolone acetonide decomposes after 5 J/cm2 of UV‐B irradiation, whereas under 30 J/cm2 of UV‐A light approximately only 20% decomposes. Both the drug and its photoproducts have been evaluated through a battery of in vitro studies and found to cause photohemolysis and induce photodamage to proteins (erythrocyte ghosts, bovine serum albumin) and linoleic acid. In addition, one of the photoproducts (the 17‐hydroperoxy derivative) is highly toxic in the dark. Therefore, both loss of therapeutic activity and light‐induced adverse effects may be expected when patients expose themselves to sunlight after drug administration. A major mechanism for phototoxicity involves radicals forming from drug breakdown, at least under UV‐B, although reactive oxygen species may play a role, particularly under UV‐A.
The Ultraviolet Radiation Environment of High Southern Latitudes: Springtime Behavior over a Decadal Timescale¶
Authors: Liao Yixiang , Frederick John E. 
Published: July 2010

ABSTRACTFour spectroradiometers located at latitudes from 55° to 90°S conducted near‐continuous measurements of ground‐level solar ultraviolet irradiance from 1990 through 2001. The behavior during months from October through December is of special interest because this period includes the springtime loss in column ozone and the naturally large irradiances of early summer. Monthly integrated irradiances using biological weightings for erythema and damage to DNA show a distortion of the normal annual cycle in irradiance, with enhanced values occurring in October and November. In some cases, these irradiances exceed those near summer solstice in December. Changes in local cloudiness and column ozone both contribute significantly to interannual variability in erythemal irradiance. This is particularly the case at Palmer Station, near 65°S, where the monthly integrated erythemal irradiance in November 1997 was more than double that observed 5 years earlier. In general, at sites on the Antarctic continent, interannual variability in monthly integrated erythemal irradiance is greatest in November, when the observation for any given year can fall 40% above or below the multiyear mean. Near the tip of South America, interannual variability is approximately half that seen in Antarctica.
Sensitized Photooxidation of Thyroidal Hormones. Evidence for Heavy Atom Effect on Singlet Molecular Oxygen [O2(1Δg)]‐mediated Photoreactions¶
Authors: Miskoski Sandra , Soltermann Arnaldo T. , Molina Patricia G. , Gönther Germán , Zanocco Antonio L. , García Norman A. 
Published: July 2010

ABSTRACTThyronine derivatives are essential indicators of thyroid gland diseases in clinical diagnosis and are currently used as standards for developing ordinary biochemical assays. Photooxidation of gland hormones of the thyronine (TN) family and structurally related compounds (TN, 3,5‐diiodo‐thyronine,3,3′,5‐triiodothyronine and 3,3′,5,5′‐tetraiodothyronine or thyroxine) was studied using rose bengal, eosin and perinaphthenone (PN) as dye sensitizers. Tyrosine (Tyr) and two iodinated derivatives (3‐iodotyrosine and 3,5‐diiodotyrosine) were also included in the study for comparative purposes. Irradiation of aqueous solutions of substrates containing xanthene dyes with visible light triggers a complex series of competitive interactions, which include the triplet excited state of the dye (3Xdye*) and singlet molecular oxygen [O2(1Δg)]‐mediated and superoxide ion‐mediated reactions. Rate constants for interaction with the 3Xdye*, attributed to an electron transfer process, are in the order of 108‐109M−1 s−1 depending on the dye and the particular substrate. The photosensitization using PN follows a pure Type‐II (O2(1Δg) mediated) mechanism. The presence of the phenolic group in Tyr, TN and iodinated derivatives dominates the kinetics of photooxidation of these compounds. The reactive rate constants, kr, and the quotient between reactive and overall rate constants (krlkt values, in the range of 0.7–0.06) behave in an opposite fashion compared with the overall rate constants and oxidation potentials. This apparent inconsistency was interpreted on the basis of an internal heavy atom effect, favoring the intersystem‐crossing deactivation route within the encounter complex with the concomitant reduction of effective photooxidation.
Interaction of UV Radiation and Inorganic Carbon Supply in the Inhibition of Photosynthesis: Spectral and Temporal Responses of Two Marine Picoplankters¶
Authors: Sobrino Cristina , Neale Patrick J. , Lubián Luis M. 
Published: July 2010

ABSTRACTThe effect of ultraviolet radiation (UVR) on inhibition of photosynthesis was studied in two species of marine picoplankton with different carbon concentration mechanisms: Nannochloropsis gaditana Lubián possesses a bicarbonate uptake system and Nannochloris atomus Butcher a CO2 active transport system. Biological weighting functions (BWFs) for inhibition of photosynthesis by UVR and photosynthesis vs irradiance (PI) curves for photosynthetically active radiation (PAR) were estimated for both species grown with an enriched CO2 supply (high dissolved inorganic carbon [DIC]: 1% CO2 in air) and in atmospheric CO2 levels (low DIC: 0.03% CO2). The response to UVR and PAR exposures was different in each species depending on the DIC treatment. Under PAR exposure, rates of maximum photosynthesis were similar between treatments in N. gaditana. However, the cultures growing in high DIC had lower sensitivity to UVR than the low DIC cultures. In contrast, N. atomus had higher rates of photosynthesis under PAR exposure with high DIC, but the BWFs were not significantly different between treatments. The results suggest that one or more processes in N. gaditana associated with HCO3− transport are target(s) for UV photodamage because there was relatively less UV inhibition of the high DIC‐grown cultures in which inorganic carbon fixation is supplied by passive CO2 diffusion. Time courses of photochemical efficiency in PAR, during UV exposure and during subsequent recovery in PAR, were determined using a pulse amplitude modulated fluorometer. The results were consistent with the BWFs. In all time courses, a steady state was obtained after an initial decrease, consistent with a dynamic balance between damage and repair as found for other phytoplankton. However, the relationship of response to exposure showed a steep decline in activity that is consistent with a constant rate of repair. A novel feature of a model developed from a constant repair rate is an explicit threshold for photosynthetic response to UV.
Effects of lodide on the Fluorescence and Activity of the Hydroperoxyflavin Intermediate of Vibrio harveyi Luciferase¶
Authors: Huang Shouqin , Tu Shiao‐Chun 
Published: July 2010

ABSTRACTThe 4a‐hydroperoxy‐4a,5‐dihydroFMN intermediate (II or HFOOH) of Vibrio harveyi luciferase is known to transform from a low quantum yield IIx to a high quantum yield (λmax 485 nm, uncorrected) IIy fluorescent species on exposure to excitation light. Similar results were observed with II prepared from the αH44A luciferase mutant, which is very weak in bioluminescence activity. Because of the rapid decay of the αH44A II, its true fluorescence was obscured by the more intense 520 nm fluorescence (uncorrected) from its decay product oxidized flavin mononucleotide (FMN). Potassium iodide (KI) at 0.2 M was effective in quenching the FMN fluorescence, leaving the 485 nm fluorescence of II from both the wild‐type (WT) and αH44A luciferase readily detectable. For both II species, the luciferase‐bound peroxyflavin was well shielded from KI quenching. KI also enhanced the decay rates of both the WT and αH44A II. For αH44A, the transformation of IIx to IIy can be induced by KI in the dark, and it is proposed to be a consequence of a luciferase conformational change. The WT II formed a bioluminescence‐inactive complex with KI, resulting in two distinct decay time courses based on absorption changes and decreases of bioluminescence activity of II.
Molecular Beacon Probes of Photodamage in Thymine and Uracil Oligonucleotides¶
Authors: Yarasi Soujanya , McConachie Cheryl , Loppnow Glen R. 
Published: July 2010

ABSTRACTMolecular beacons (MB) are becoming more common as sequence‐selective detectors of nucleic acids. Although they can easily detect single‐base mismatches, they have never been used to directly detect DNA or RNA damage. To measure the degree of ultraviolet (UV) light damage in oligonucleotides, we report a novel MB approach for general detection of photoproducts in UV‐irradiated rU17 and dT17 oligonucleotides. With monochromatic UV light irradiation at ca 280 nm under anoxic conditions, the oligonucleotide absorption decays with a single‐exponential time constant of 123 ± 1 min for rU17 and with double‐exponential time constants of 78 ± 0.5 min (99%) and 180 ± 5 min (0.05%) for dT17 oligonucleotides. Under the same conditions, the MB fluorescence decays more quickly, with single‐exponential time constants of 19 ± 2 and 26 ± 3 min for rU17 and dT17, respectively. Similar kinetics were observed with broadband UV light irradiation of oligonucleotides. The differences in the UV damage kinetics of dT17 and rU17 and their detection by absorption and fluorescence techniques will be discussed in the context of differential instabilities introduced in the nucleic acid‐MB duplex by the different photoproducts formed.
An Action Spectrum of the Riboflavin‐photosensitized Inactivation of Lambda Phage¶
Authors: Martin Christopher B. , Wilfong Erin , Ruane Patrick , Goodrich Raymond , Platz Matthew 
Published: July 2010

ABSTRACTThe Action Spectrum of riboflavin (RB) sensitized inactivation of lambda phage was determined between 266 and 575 nm. Below 304 nm, RB depresses the phage reduction by screening phage from radiation that it would otherwise absorb directly. Between 308 and 525 nm, RB sensitizes the inactivation of phage. Enhanced phage reduction is observed at 320 and 500 nm because of binding of RB to the phage and the shifting of the absorption curve of the phage‐bound flavin relative to free flavin in phosphate‐buffered saline. Enhanced inactivation at 320 and 500 nm and depressed phage inactivation between 360 and 410 nm is also influenced by the inner filter effect.
Update on the Positive Effects of Light in Humans†
Authors: Roberts Joan E. 
Published: July 2010

ABSTRACTThe adverse effects of sunlight, from melanoma to cataracts, are well known and frequently reported (1). However, because humans evolved under sunlight, it is not surprising that there are many positive effects of light on human health. Light that reaches the human eye has two fundamental biological functions: regulation of the visual cycle and of circadian rhythm. We report here the most recent developments in both of these areas.