bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECTS OF CHRONIC EXPOSURE ULTRAVIOLET‐A INCLUDING 2% ULTRAVIOLET‐B ON FREE RADICAL REDUCTION SYSTEMS IN HAIRLESS MICE
Authors: Maeda Kazuhisa , Naganuma Masako , Fukuda Minoru 
Published: January 2008

AbstractChronic ultraviolet (UV) irradiation is known to cause a variety of changes in the skin, including wrinkles, pigmented spots and carcinogenesis. To explore time dependent changes in several parameters with chronic UV irradiation, we examined the molecular changes in connective tissue, intracellular defence enzymes and free radical antioxidant substances in hairless mice skin caused by chronic exposure to UV‐A including 2% UV‐B. Connective tissue changes were estimated using hydroxyproline and isodesmosine assays as a measure of collagen and elastin concentrations, respectively.After 6 weeks irradiation, the insoluble collagen and elastin were both substantially elevated, as were the activities of glutathione peroxidase (GSH‐Px) and superoxide dismutase (SOD). Continued UV irradiation resulted in a steady decline in SOD and lipid soluble antioxidants, while the GSH‐Px remained elevated, suggesting that SOD and lipid soluble antioxidants in the skin may be involved in protecting it from UV damage and deteriorate with chronic irradiation.
RELATIVE INDUCTION OF CYCLOBUTANE DIMERS and CYTOSINE PHOTOHYDRATES IN DNA IRRADIATED in vitro and in vivo WITH ULTRAVIOLET‐C and ULTRAVIOLET‐B LIGHT
Authors: Mitchell David L. , Jen Jin , Cleaver James E. 
Published: January 2008

AbstractSV40 DNA was irradiated in vitro and in vivo with UV‐C (240–280nm) and UV‐B (280–320nm) light, and damaged sites sensitive to digestion with Escherichia coli endonuclease III (endo III) and bacteriophage T4 endonuclease V (endo V) were quantified. The frequency of endo Ill‐sensitive sites (primarily cytosine photohydrates) induced was1–2% of the frequency of endo V‐sensitive sites (cyclobutane dimers) in both purified SV40 DNA and intracellular episomal SV40 DNA. Endo III‐ and endo V‐sensitive sites in DNA were induced in the same relative proportion at both UV‐C and UV‐B wavelengths. We found no evidence to support earlier inferences that intracellular conditions enhance the formation of cytosine photohydrates or other monobasic forms of DNA damage.
ENHANCEMENT OF ULTRAVIOLET‐DNA REPAIR IN den V GENE TRANSFECTANTS and T4 ENDONUCLEASE V‐LIPOSOME RECIPIENTS
Authors: Kibitel Jeannie Tsimis , Yee Vivian , Yarosh Daniel B. 
Published: January 2008

AbstractThe phage T4 deri V gene, coding for the pyrimidine‐dimer specific T4 endonuclease V, was transfected into human repair‐proficient fibroblasts, repair‐deficient xeroderma pigmentosum fibroblasts, and into wild type CHO hamster cells. Transfectants maintained den V DNA and expressed deri V raRNA. Purified T4 endonuclease V encapsulated in liposomes was also used to treat repair‐proficient and ‐deficient human cells. The den V transfected clones and liposome‐treated cells showed increased unscheduled DNA synthesis and enhanced removal of pyrimidine dimers compared to controls. Both den V gene transfection and endonuclease V liposome treatment enhanced post‐UV survival in xeroderma pigmentosum cells but had no effect on survival in repair‐proficient human or hamster cells. The results demonstrate that an exogenous DNA repair enzyme can correct the DNA repair defect in xeroderma pigmentosum cells and enhance DNA repair in normal cells.
EFFECTS OF ULTRAVIOLET LASER RADIATION ON VENEZUELAN EQUINE ENCEPHALOMYELITIS VIRUS*
Authors: Nikogosyan David N. , Kapituletz Sergei P. , Smirnov Yuri A. 
Published: January 2008

AbstractThe effects of usual low‐intensity continuous (Λ= 254 nm,I= 10 W/m2) UV radiation and high‐intensity laser nanosecond (Λ= 266 nm, ‐τp= 10 ns,I= 109W/m2) or picosecond (Λ= 266 nm, τP= 23 ps,I= 1012W/m2) UV radiation on Venezuelan equine encephalomyelitis virus (a member of the Togaviridae family) were compared. The quantum yields of infectivity inactivation, pyrimidine dimer formation and RNA‐protein crosslinking were determined.
RELATIONSHIP BETWEEN LIGHT QUALITY DEPENDENCE AND IRRADIANCE ADAPTATION OF PHOTOSYNTHESIS IN Acetabularia mediterranea*
Authors: SCHMID RAINER 
Published: January 2008

Abstract—Characteristic differences in the light intensity curves of photosynthesis after growth of cells of Acetabularia mediterranea Lamour. (A. acetabulum (L.) Silva) in weak and strong white light were similar to those for red and blue light‐treated cells, respectively. This indicated that responses to white light quantity and those to light quality might be causally related. Small differences in the thylakoid polypeptide composition of cells grown in high and low intensities of white light were not significant and thus did not help to clarify whether the adaptations to blue or red light, respectively, were the same.When the red to blue‐light ratio was varied, keeping the total photon fluence rate constant, the photosynthetic capacity (red light saturated O2‐production) was dependent on blue light irradiance in a logarithmic fashion. The specific influence of red light was not detectable, indicating that only blue light was effective for light irradiance adaptation in Acetabularia.The situation was different, at least for a transient period, when adaptation to light irradiance was allowed to proceed from a low photosynthetic activity after preirradiation of the cells with prolonged red light. The effect of low white light irradiances was pronounced, causing a maximum increase of photosynthetic activity within 3 days. The response to blue light was enhanced as well, and a very low photon irradiance added to continuous red light caused a change of the same order as that produced by high irradiances of blue light alone. This elevated action of low intensity white and blue light is most likely due to increased metabolite supply derived from the degradation of starch enhanced by this light quality. Therefore, photosynthetic effectiveness in Acetabularia is regulated by the irradiance of blue light and by feedback via photosynthetic products.
ELECTRONIC STATES OF THE INDOLE‐ACRYLAMIDE MOLECULAR PAIR
Authors: ILICH PREDRAG , PRENDERGAST FRANKLYN G. 
Published: January 2008

Abstract—A model is suggested for tryptophan fluorescence quenching by acrylamide based on the prediction that acrylamide can absorb a photon from the excited indole moiety and then dissipate the optical energy into a sink of fast exchanging conformations. Semiempirical electronic structure calculations of the indole‐acrylamide pair indicate little actual intermolecular orbital mixing a1 van der Waals contact distances. However, the two lowest singlet transitions of the molecular pair, assigned to the acrylamide {π*}←n(O) line and to the indole 1Lb←1A1 line, respectively, vary significantly in energies and in transition and excited state moments with the geometry of interaction between the two entities. The distribution of optimal quenching coordinations depends separately on the benzene and pyrrole portions and has a distinctly non‐spherical shape at these distances.
FLUORESCENCE ENERGY TRANSFER BETWEEN DIMETHYLDIAZAPEROPYRENIUM DICATION AND ETHIDIUM INTERCALATED IN POLY d(A‐T)
Authors: MERGNY JEAN‐LOUIS , SLAMA‐SCHWOK ANNY , MONTENAY‐GARESTIER THÉRÈSE , ROUGÉE MICHEL , HÉLÈNE CLAUDE 
Published: January 2008

Abstract—Dimethyldiazaperopyrenium is one of the largest known DNA intercalators. Fluorescence energy transfer occurred between dimethyldiazaperopyrenium (donor) and ethidium (acceptor) when these dyes were bound to a double‐stranded polynucleotide such as poly d(A‐T). The addition of increasing amounts of ethidium bromide led to a marked shortening of the fluorescence lifetime of the donor, whereas the excited state of the acceptor was progressively populated via energy transfer from the donor. Critical Förster distance between these two chromophores was calculated to be 3.8 nm. The observed transfer efficiency was lower than that calculated on the basis of this critical distance and a statistical distribution of bound drugs. These results are discussed taking into account the conformational change induced by intercalation of dimethyldiazaperopyrenium in the double‐stranded polynucleotide.
ATMOSPHERIC SUN PROTECTION FACTOR ON CLEAR DAYS: ITS OBSERVED DEPENDENCE ON SOLAR ZENITH ANGLE AND ITS RELEVANCE TO THE SHADOW RULE FOR SUN PROTECTION
Authors: Holloway Leith 
Published: January 2008

Abstract—Global irradiances measured in seven 5‐nm bands of UV‐B at Rockville, MD (39.1°N, 77.1oW) on 28 clear days near the summer solstice are convoluted with the erythemal action spectrum of human skin to determine dose rates at various hours of the day. These rates are averaged with respect to solar zenith angle to obtain the diurnal variation of mean dose rate and of the Sun Protection Factor (SPF) of the atmosphere (reciprocal of the normalized atmospheric transmissivity) on a typical clear summer day in Rockville. At a 45o zenith angle the atmospheric SPF is computed to be 2.7 and increases rapidly to greater than 7 at 60o.Dose rates are integrated with respect to time to obtain estimates of mean doses for various periods during clear days at Rockville in mid summer and near the autumnal equinox. In mid summer the effective erythemal UV‐B exposure during the period when the solar zenith angle is less than 45o is about five times greater than that during the remainder of the day. These observations provide scientific basis for a shadow rule for solar UV‐B protection: when shadows are shorter than objects casting them, sunburn is much more likely than at other times.
TUMORICIDAL CAPACITIES OF MACROPHAGES PHOTODYNAMICALLY ACTIVATED WITH HEMATOPORPHYRIN DERIVATIVE
Authors: Yamamoto Nobuto , Hoober J. Kenneth , Yamamoto Nobuyukr , Yamamoto Shinji 
Published: January 2008

Abstract—Four days after administration to mice of small amounts (30–600ng/mouse) of hematoporphyrin derivative (HPD), peritoneal macrophages exhibited a greatly enhanced Fc‐receptor mediated phagocytic capacity as assayed by ingestion activity of IgG‐coated sheep erythrocytes. Much higher doses (>3000 ng/mouse) did not have this effect. The peritoneal macrophages activated by administration of HPD have tumoricidal capacity for IgG‐coated retinoblastoma cells. We then studied in vitro photodynamic activation of macrophages by white and red fluorescent light irradiation of mouse peritoneal cells (mixture of macrophages and B and T lymphocytes) in media containing very low concentrations of HPD. A short (5 s) white fluorescent light exposure (lWm‐2) of peritoneal cells in a medium containing 0.03 ng HPD/mL produced the maximal level of ingestion activity of macrophages. A 15 s red fluorescent light exposure (lWm‐Z) of peritoneal cells in a medium containing 0.1 ng HPD/mL produced the maximal level of ingestion activity of macrophages. Thus, photodynamic activation of macrophages with white fluorescent light is more efficient than that with red fluorescent light. This can be explained by the fact that HPD has a large absorption peak at about 364 nm which extends into the visible range, and decreasingly smaller absorption bands at 500, 535, 570 and 630 nm. In vitro photodynamically activated macrophages showed efficient tumoricidal activity regardless of the type (white or red) of light used. These results suggest that a low level of HPD promotes therapeutic immunopotentiation
THE EFFECT OF SYSTEMIC CYCLOSPORIN A ON A HAIRLESS MOUSE MODEL OF PHOTOAGING
Authors: Moloney Stephen J. , Learn Douglas B. 
Published: January 2008

Abstract—The mechanisms that cause skin wrinkling in response to chronic exposure to sunlight are unknown. We investigated the possibility that wrinkling of Skh‐1 hairless mice is associated with an ultraviolet (UV) radiation‐induced immunologic alteration. Exposing Skh‐1 hairless mice to a regimen of nonerythemal UV‐B (290–320 nm) radiation induced skin wrinkles after 6–7 weeks. Concomitant treatment with cyclosporin A decreased the time to the onset of wrinkles to approximately 4 weeks. Exposing HRS/J hairless mice or athymic nude mice to a similar nonerythemal UV‐B radiation regimen for 10 weeks failed to induce skin wrinkles. Concomitant administration of cyclosporin A and UV‐B radiation for 7 weeks to HRS/J hairless mice induced no skin wrinkles. Ultraviolet‐B or UV‐B plus cyclosporin A exposure caused increased immunohistochemical staining for Ia and F4/80 antigens in the upper dermis of tissue from Skh‐1 mice, as compared to controls. Treating Skh‐1 mice with UV‐B radiation plus cyclosporin A was also associated with a large increase in the number of CD3+ cells in the dermis. These staining patterns were absent in similarly treated HRS/J hairless mice. Dermal mast cell numbers in Skh‐1 mice were 2–3‐fold higher than in HRS/J, athymic nude or NSA mice. Treatment with cyclosporin A increased Skh‐1 dermal mast cell numbers approximately 2‐fold but had no effect on the dermal mast cell numbers in HRS/J or NSA mice. Based on these findings we postulate that UV‐B light and cyclosporin A exacerbate an immunological condition in Skh‐1 mice, one consequence of which is manifested as skin wrinkles. Thus, the induction of skin wrinkles in this mouse strain may have no relevance to the wrinkles observed in human skin after chronic exposure to sunlight.
THE EFFECT OF LIGHT QUALITY IN Prunus cerasus. I. PHOTORECEPTORS INVOLVED IN INTERNODE ELONGATION AND LEAF EXPANSION IN JUVENILE PLANTS
Authors: Baraldi R. , Cristoferi G. , Facini O. , Lercari B. 
Published: January 2008

Abstract—Evidence is presented to suggest that stem elongation in this woody species is controlled not only by phytochrome as previously suggested for other woody species, but also by a specific blue absorbing pigment (BAP). In contrast, the BAP seems to have no role to play in the development of total leaf area in these juvenile specimens.
EFFECT OF CALCIUM ON DARK ADAPTATION IN Phycornyces PHOTOTROPISM
Authors: Sineshchekov Alexey V. , Lipson Edward D. 
Published: January 2008

Abstract—Adaptation processes enable phototropism of Phycomyces to operate over a 10‐decade range of blue‐light intensity (1 nW m−2‐10 W m‐2). To investigate the influence of calcium on dark adaptation, the phototropic latency method was employed with the modification that sporangiophores were temporarily immersed in solutions containing CaCI2 or LaCI3 Following such treatment, the time course of bending was found to have two components with distinct latencies and bending rates. After immersion in darkness for 30 min in LaCI3 solution or 1 h in a solution of CaCI2 MgCI2, or the calcium chelator EGTA, each sporangiophore was adapted to a blue light beam (1 W m‐2) for 45 min by rotation around its vertical axis. Cessation of rotation defined the onset of the phototropic stimulus, at which time the intensity was reduced by as much as 103‐fold. For a 102‐fold reduction (to 10−2 W m−2), immersion in CaCl2 (10–100 μM) reduces the latency 13 min for the early bending component and 18 min for the late component, whereas treatment with the calcium‐channel blocker lanthanum (0.1–11 μM LaCI3) increases the latency 12 min for the early component and 13 min for the late component. EGTA (10 μM) also had an inhibitory effect, increasing the latency of the first and the second components by 7 and 10 min, respectively. In experiments performed similarly, but without the light adaptation treatment after immersion, no differences between calcium‐treated and control sporangiophores were found. The bending rates of both components show only a weak dependence on calcium. Finally, experiments with MgCI2 (10–100 μM) were indistinguishable from control experiments, indicating that the divalent cation Mg+2, unlike Ca+2, had no effect on latency or bending rate. The results show that calcium affects the phototropic latency, and may function in the adaptation processes for Phycomyces phototropism.
STRUCTURAL STUDIES ON THE PHOTORECEPTOR PHYTOCHROME: REEVALUATION OF THE EPITOPE FOR MONOCLONAL ANTIBODY Z‐3B1
Authors: Bonenberger J. , Schendel R. , Schneider‐Poetsch H. A. W. , Rüdiger W. 
Published: January 2008

Abstract—The photoreceptor phytochrome is widely distributed in the plant kingdom from angiosperms to ferns, mosses and algae. The epitope for the monoclonal antibody Z‐3B1 which exhibits wide‐ranging cross‐reactivity with phytochromes from higher and lower plants was mapped by the combination of several methods: by Western blot with proteolytic fragments of known localization, by sequence comparison of phytochromes from various plants, and by production of overlapping fusion proteins. The only sequence which is common to all positively‐reacting fusion proteins is the sequence A‐830 to R‐859. This sequence must contain the Z‐3B1 epitope. The best candidate is suggested to be the T‐cell antigenic sequence K‐Y‐ V/I‐E‐A/C‐L‐L‐T (=K‐848 to T‐855). The significance of the highly conserved epitope in all phytochromes is discussed.
EXPRESSION OF OAT phyA cDNA IN THE MOSS Ceratodon purpureus
Authors: Thümmler Fritz , Schuster Harald , Bonenberger Johannes 
Published: January 2008

Abstract—The possibility of transforming Cerarodon purpureus protoplasts by PEG‐mediated direct DNA uptake was tested. Transformation with a plasmid carrying a kanamycin‐resistance gene resulted in kanamycin‐resistant colonies of C. purpureus protonemata. A full‐length cDNA clone coding for oat phyA phytochrome was isolated. The clone HM4.1 which is 3.7‐kb long exhibits about 99% nucleotide sequence identity to the known phytochrome clone AP3. The expression of HM4.1 in C. purpureus protonemata was tested. A construct with the 35s‐promotor and the structural gene of HM4.1 was cotransformed with the plasmid containing the kanamycin‐resitance. Kanamycin‐resistant colonies were tested for the presence of HM4.1 sequences in a genomic Southern experiment. Two out of 19 kanamycin‐resistant colonies reacted positively with a HM4.1 specific probe. The expression of phyA in the positive colonies was examined with monoclonal antibodies specific for oat phytochrome. The Western blot experiment with protein extracts of the two positive colonies grown in the dark revealed clear signals at 124‐kDa which were not detected in control plants. These data demonstrate the possibility of expressing oat phyA‐apoprotein in C. purpureus protonemata. The transgenic moss protonemata did not show phenotypical alterations in response to the foreign phytochrome polypeptide; it is not known at the moment if the tetrapyrole chromophore is attached to the oat polypeptide in the protonemata or not.
THE ECOLOGICAL FUNCTIONS OF THE PHYTOCHROME FAMILY. CLUES TO A TRANSGENIC PROGRAMME OF CROP IMPROVEMENT
Authors: Smith Harry 
Published: January 2008

Abstract—Phytochrome‐mediated proximity perception and induction of shade avoidance responses provide clues towards a novel genetic engineering approach for the improvement of crop plants. In this Commentary Article, I argue that the elimination, or disablement, of proximity perception and the associated shade avoidance syndrome by transgenic manipulation of phytochrome genes should provide a strategy for the creation of new crop plants in which a greater proportion of assimilates is incorporated into harvestable material. Such a programme would enable increases in agricultural productivity without a requirement for the increased application of agrochemicals. Some potential approaches towards realizing these goals are proposed.
THE LIGHT‐HARVESTING SYSTEM OF THE UNICELLULAR ALGA Mantoniella squamata (PRASINOPHYCEAE): EVIDENCE FOR THE LACK OF A PHOTOSYSTEM I‐SPECIFIC ANTENNA COMPLEX
Authors: Schmitt A. , Herold A. , Welte C. , Wild A. , Wilhelm C. 
Published: January 2008

AbstractThe light‐harvesting complexes (LHC) were isolated from the unicellular alga Mantoniella squamata (Prasinophyceae) by sucrose‐density centrifugation. Beside the major LHC (II), a photosystem I complex was obtained that could be dissociated into a photosystem I core complex and an associated LHC I. In contrast to other chlorophyll b‐containing antennae, both LHC II as well as LHC I were observed to be identical with respect to the following features: the molecular weights, the isoelectric points and the retention behavior on anion‐exchange chromatography of the apoproteins, the pigment content and the absorption and fluorescence spectra. We conclude from these results that Mantoniella contains only one homogenous population of LHC, which cooperate with both photosystems not on the basis of specific recognition but on the simple basis of statistical interaction. This is the first report of a chlorophyll b‐containing light‐harvesting system without any subpopulations: therefore, it is suggested that it arises from a most primitive type of chlorophyll b‐containing chloroplast.
PIGMENT COMPLEXES OF LIGHT‐HARVESTING CHLOROPHYLL a/b BINDING PROTEIN ARE STABILIZED BY A SEGMENT IN THE CARBOXYTERMINAL HYDROPHILIC DOMAIN OF THE PROTEIN*
Authors: Paulsen Harald , Kuttkat Andrea 
Published: January 2008

AbstractIn order to identify segments of light‐harvesting chlorophyll a/6‐binding protein (LHCP) that are important for pigment binding, we have tested various LHCP mutants regarding their ability to form stable pigment‐protein complexes in an in vitro reconstitution assay. Deletion of 10 C‐terminal amino acids in the LHCP precursor, pLHCP, did not significantly affect pigment binding, whereas deletion of one additional amino acid, a tryptophan, completely abolished the formation of stable pigment‐protein complexes. This tryptophan, however, can be exchanged with other amino acids in full‐length pLHCP without noticeably altering the stability or spectroscopic properties of pigment complexes made with these mutants. Thus, the tryptophan residue is not likely to be involved in a highly specific interaction stabilizing the complex. A double mutant of LHCP lacking 66 N‐terminal and 6 C‐terminal amino acids still forms pigmented complexes that are virtually identical to those formed with the full‐length protein concerning their pigment composition and spectroscopic properties. We conclude that about 30% of the polypeptide chain in LHCP is not involved in pigment binding.
FLUORESCENCE LINE NARROWING SPECTROSCOPY OF Zn PORPHYRINS*
Authors: Logovinsky Veronika , Kaposi A. D. , Vanderkoor J. M. 
Published: January 2008

AbstractFluorescence line narrowing (FLN) spectroscopy was used to study the vibrational features of Zn porphyrins, including Zn octaethylporphine, Zn mesoporphyrin, Zn deuteroporphyrin and Zn coproporphyrin, and the interaction of these porphyrins with their solvent matrices. A number of ground‐state vibrational levels were identified for each of the Zn porphyrins. Six of these levels persistent throughout almost all spectra were analyzed in terms ofcontributions of specific internal vibrational modes of the porphyrins. A number of other vibrational levels were identified as characteristic of the peripheral substituents of Zn porphyrin. Phonon wing contribution in the FLN spectra increased with increased polarity of the solvent matrix, and the Stokes shift calculated from the conventional spectra was correlated with the strength of phonon coupling. Specific vibrational modes were found to couple differently with the solvent and to have different phonon wings. The conventional and energy‐selected spectra of Zn coproporphyrin in 5 M guanidine HCI suggest that guanidine ligates to the Zn atom.