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Showing papers on "Ultraviolet light published in 1984"


Book ChapterDOI
TL;DR: Ultraviolet spectrophometric detection of conjugated dienes has been used for many years in the food industry for the detection of autoxidized lipids and for a variety of pathological processes, the question has been raised whether peroxidative decomposition of membrane lipids has occurred in vivo.
Abstract: Publisher Summary Like many other substances, naturally occurring lipids exhibit simple end absorption in ultraviolet light as the wavelength is lowered toward 200 nm. The spectra of a variety of organic molecules containing conjugated dienes, however, are characterized by intense absorption, the so-called K band, which may range, with respect to peak absorption, from 215 to 250 nm, depending on nearby substituent groups. Ultraviolet spectrophometric detection of conjugated dienes has been used for many years in the food industry for the detection of autoxidized lipids. The method appears to have been applied for the first time to the problem of liver cell lipid peroxidation of toxigenic origin in 1966 and has been widely used since. For a variety of pathological processes, the question has been raised whether peroxidative decomposition of membrane lipids has occurred in vivo. A second principle of the method recognizes that for whole-animal studies involving possible lipid peroxidation, the fraction of endogenous lipids actually peroxidized may not only be low, but the process of lipid peroxidation may be confined to a particular subcellular structure.

454 citations


Journal ArticleDOI
TL;DR: In this paper, the 1, 2-bis(10, 12-tricosadiynoyl)-sn-glycero-3-phosphocholine, in which both fatty acyl chains contain polymerizable diacetylenic units, has been studied with regard to its behavior in aqueous dispersion before and after polymerization.
Abstract: The 1, 2-bis(10, 12-tricosadiynoyl)-sn-glycero-3-phosphocholine, in which both fatty acyl chains contain polymerizable diacetylenic units, has been studied with regard to its behavior in aqueous dispersion before and after polymerization. The monomeric lipid may be dispersed in distilled water above its chain melting transition temperature, but, contrary to previous reports, it does not stay in liposomal form on subsequent reduction of the temperature. Microscopic observation shows formation of structures resembling so-called cochleate cylinders, except that these cylinders are water-filled. These "tubules" reversibly convert to liposomal form on heating above the monomer chain melting temperature. However, on polymerization with ultraviolet light, the cylinders are “locked in” and no morphological changes are observed on heating. These unique structures may represent a new class of orientable polymers.

335 citations


Journal ArticleDOI
TL;DR: Experiments show that ultraviolet light-irradiated, cultured human keratinocytes bind IgG antibodies from the sera of LE patients with either monospecific anti-SSA/Ro, anti-RNP, or anti-Sm activity, which implies that these antigens have been made accessible on the cell surface by ultraviolet irradiation.
Abstract: Antibodies which bind to different nuclear antigens in tissue sections or in permeabilized cell cultures are useful markers of subsets of connective tissue disease, especially of lupus erythematosus (LE), but whether these antibodies are able to react with these intracellular sequestered antigens in vivo and cause immunologic tissue damage has been a matter of much debate. We report experiments which show that ultraviolet light-irradiated, cultured human keratinocytes bind IgG antibodies from the sera of LE patients with either monospecific anti-SSA/Ro, anti-RNP, or anti-Sm activity, which implies that these antigens have been made accessible on the cell surface by ultraviolet irradiation. Normal human sera or LE patient's sera with anti-double-stranded DNA, anti-single-stranded DNA, or antihistone activity do not bind to the surface of irradiated human keratinocytes. In control experiments, all antisera produced the expected patterns of nuclear and cytoplasmic staining of fixed permeabilized, unirradiated keratinocytes. Careful study of the viability and permeability of irradiated keratinocytes by several techniques showed that this apparent cell membrane expression of extractable nuclear antigens (SSA/Ro, RNP, and Sm) following irradiation was seen on injured keratinocytes whose cell membranes were intact, but not on dead cells. It is particularly significant that all six monospecific anti-SSA/Ro sera bound to irradiated keratinocytes, since this antibody antigen system is highly associated with photosensitive cutaneous LE.

326 citations


Patent
10 Jul 1984
TL;DR: In this paper, the ultraviolet light absorbing polymer compositions comprising copolymers of 2-Hydroxy-5-acrylyloxyphenyl-2H-benzotriazoles with one or more other monomers copolymerizable therewith, particularly acrylic monomers are useful in the manufacture of occular devices, particularly intraoccular lenses and contact lenses.
Abstract: Ultraviolet light absorbing polymer compositions comprising copolymers of 2-Hydroxy-5-acrylyloxyphenyl-2H-benzotriazoles with one or more other monomers copolymerizable therewith, particularly acrylic monomers are useful in the manufacture of occular devices, particularly intraoccular lenses and contact lenses. Polymers of the disclosed benzotriazoles may be added to other organic materials to impart ultraviolet absorbing properties thereo.

286 citations


Journal ArticleDOI
TL;DR: It is found that one to three blastomeres transplanted from the vegetal-most octet of cells can effect complete or partial rescue of of axis development in a recipient, provided that the donor cells derive from the quadrant just under the prospective dorsal marginal region.

280 citations


Journal ArticleDOI
02 Mar 1984-Science
TL;DR: Evidence has been obtained that this C-H insertion, or oxidative addition, reaction proceeds through a simple three-center transition state and does not involve organic free radicals as intermediates, providing an incentive for reexamining the factors that have been assumed to control the rate of reaction of transition metal complexes with C-h bonds.
Abstract: Alkanes, although plentiful enough to be considered for use as feedstocks in large-scale chemical processes, are so unreactive that relatively few chemical reagents have been developed to convert them to molecules having useful functional groups. However, a recently synthesized iridium (lr) complex successfully converts alkanes into hydridoalkylmetal complexes (M + R-H → R-M-H). This is a dihydride having the formula Cp*(L)lrH2, where Cp* and L are abbreviations for the ligands (CH3)5C5 and (CH3)3P, respectively. Irradiation with ultraviolet light causes the dihydride to lose H2, generating the reactive intermediate Cp*lrL. This intermediate reacts rapidly with C-H bonds in every molecule so far tested (including alkanes) and leads to hydridoalkyliridium complexes Cp*(L)lr(R)(H). Evidence has been obtained that this C-H insertion, or oxidative addition, reaction proceeds through a simple three-center transition state and does not involve organic free radicals as intermediates. Thus the intermediate Cp*lrL reacts most rapidly with C-H bonds having relatively high bond energies, such as those at primary carbon centers, in small organic rings, and in aromatic rings. This contrasts directly with the type of hydrogen-abstraction selectivity that is characteristic of organic radicals. The hydridoalkyliridium products of the insertion reactions can be converted into functionalized organic molecules—alkyl halides—by treatment with mercuric chloride followed by halogens. Expulsion (reductive elimination) of the hydrocarbon from the hydridoalkyliridium complexes can be induced by Lewis acids or heat, regenerating the reactive intermediate Cp*lrL. Oxidative addition of the corresponding rhodium complexes Cp*RhL to alkane C-H bonds has also been observed, although the products formed in this case are much less stable and undergo reductive elimination at -20°C. These and other recent observations provide an incentive for reexamining the factors that have been assumed to control the rate of reaction of transition metal complexes with C-H bonds—notably the need for electron-rich metals and the proximity of reacting centers.

278 citations


Journal ArticleDOI
TL;DR: A new mutation (recQ1) located between corA and metE on the standard linkage map was found to result in increased sensitivity to ultraviolet light and deficiency in conjugational recombination when placed in the recBC sbcB background, indicating that it blocked the RecF pathway of recobbination.
Abstract: An Escherichia coli K12 mutant resistant to thymineless death (TLD) was isolated, and its genetic analysis led us to identify a new mutation (recQ1) located between corA and metE on the standard linkage map. The mutation was found to result in increased sensitivity to ultraviolet light and deficiency in conjugational recombination when placed in the recBC sbcB background, indicating that it blocked the RecF pathway of recobbination. It seemed likely that this mutation is also capable of causing partial resistance to TLD, but we reserve the possibility of a separate mutation closely linked to recQ1 giving rise to this phenotype. The original mutant was shown to carry an additional mutation probably in the vicinity of the uhp locus, which was also required for the full TLD resistance of the mutant to be expressed.

242 citations


Journal ArticleDOI
TL;DR: In BaFX:Eu 2+, the excitation by X-ray or ultraviolet light and the photostimulation of luminescence by visible light are caused by the processes of Eu 2 + ⇌Eu 3+ and F + -centers⇌F.

204 citations


BookDOI
01 Jan 1984
TL;DR: Blue Light Effects on the Level of Translation and Transcription, Nature and Properties of the Photoreceptors, and Genetic Analysis and Molecular Biology of Blue Light Responses.
Abstract: Diversity of Photoreceptors.- The Blue Light Responses in Evolutionary Studies.- Coaction of Phytochrome and Blue/UV Light Photoreceptors.- Effects of UV Radiation on Plants in the Transition Region to Blue Light.- Mycochrome System in the Induction of Fungal Conidiation.- Near-UV and Blue Light Effects in Cyanobacteria.- Blue light Effects in Halobacteria.- Orange/Yellow Pigments in the Basidiomycete Pleurotus ostreatus (Jacq.ex.Fr.) Kummer.- Blue and Ultraviolet Light in Eyes: Primary Reactions and Light-Induced Metabolic Changes.- Cryptochrome, Some Terminological Thoughts.- Nature and Properties of the Photoreceptors.- Photophysical Aspects of Blue Light Receptors: The Old Question (Flavins Versus Carotenoids) Re-Examined.- The Study of Basic Photochemical and Photophysical Properties of Membrane-Bound Flavins: The Indispensible Prerequisite for the Elucidation of Primary Physiological Blue Light Action.- The Nitrate Reductas System.- Re-Examination of Action Spectroscopy in Blue/Near-UV Light Effects.- Photogeotropism of Phycomyces: Evidence for More Than One Photoreceptor.- Ultraviolet Photoreceptors and Their Interaction in Broom Sorghum - Analysis of Action Spectra and Fluence - Response Curves.- Multiple Effects of the Flavin Quencher Potassium Iodide on light- and Dark-Processes in the Green Alga Mougeotia.- Molecular Interaction Between Riboflavin and Salicylic Acid Derivatives in Non Polar Solvents.- ESR of Transition Metal "Chromophores" in RuBPCase. Supporting Neutron Activation and Optical Data. Concepts of UV light Activation Through Transition Metal Chromophores.- Primary Events and Signal Transduction.- A Light Inducible Cytochrome b Reduction in the Green Alga Acetabularia.- Blue Light Effects and the Role of Membranes.- Localization of Light-Induced Phenylacetic Acid-Binding Sites in Corn Coleoptile Membranes: Possible Association of the Blue Light Photoreceptor Pigment with the Plasma Membrane.- Wavelength Dependence of Nitrite Release and the Effects of Different Nitrogen Sources and CO2 Tensions on Chlamydomonas reinhardii Inorganic Nitrogen Metabolism.- Photoreceptor Mechanism of Neurospora crassa: Control Over the Electrophysiological Properties of Cell Membrane and Over the Level of Nucleotide Regulators.- Genetic Analysis and Molecular Biology of Blue Light Responses.- Genetic Analysis of Blue Light-Induced Responses in Neurospora crassa.- Genetic Determination of the Responses of Phycomyces to Light.- Blue light Receptors in Phycomyces Investigated by Action Spectroscopy, Fluorescence Lifetime Spectroscopy, and Two-Dimensional Gel Electrophoresis.- The Quest for Trichoderma Cryptochrome.- Enzyme Regulation and Carbohydrate Metabolism.- Blue Light Effects on the Level of Translation and Transcription.- Light-Induced Changes in the Protein Pattern Translated in Vivo and in Vitro Accompanying Carotenogenesis in Neurospora crassa and Fusarium aquaeductuum.- Light-Dependent Greening of the Chlorella Mutant G-2: Spectral Dependency and Chloroplast Translation Effects.- Increase in RNA by Blue Light in a Chlorophyll-Free Chlorella Mutant.- Enzyme Regulation and Carbohydrate Metabolism.- Effects of Blue Light on Enzymes.- Influence of Blue Light on NADP-Dependent Glyceraldehyde 3-Phosphate Dehydrogenase Activity in Chorella.- Enhancement by Blue Light of GOGAT Activity in Chlorella.- Blue Light Effects on Carbon Metabolism in Dunaliella.- 31P-NMR Studies in Scenedesmus C-2A' in Darkness and Blue Light.- Pigment Biosynthesis.- Effects of Blue Light on the Formation of 5-Aminolevulinic Acid and Chlorophyll in Cultured Tobacco Cells.- The Blue Light Factor in Sun and Shade Plant Adaptation.- Chlorophyll a/Chlorophyll b Ratios of Chlorella vulgaris in Blue or Red Light.- The Influence of Blue Light on the Formation of Chlorophyll-Protein Complexes in Scenedesmus.- Carotenogenesis.- Blue/UV Light Effects on Anthocyanin Synthesis.- Development.- Blue Light Effects in Cell Cultures.- Blue Light Effects on Chloroplast Development in Higher Plants.- Control of the Activity of Photosynthetic Apparatus in Higher Plants.- Blue Light Effects on Morphogenesis and Metabolism in Acetabularia.- Movement and Growth.- Photomovement.- Chloroplast Displacement Response to Blue Light Pulses.- Flavin-Mediated Weak-Light Chloroplast Movement in Mougeotia.- Influence of ATPase Inhibitors on Light-Dependent Movement of Chloroplasts in Vallisneria.- Photoaxis and Photomorphogenesis in Physarum polycephalum Plasmodia.- Red Light-Induced Shift of the Fluence-Response Curve for First Positive Phototropic Curvature of Maize Coleoptiles.- The Possible Role of H+ and Ca2+ in Photobehavior of Blepharisma japonicum.- Blue Light and Stomatal Function.- Oecological Aspects.- Responses of Unicellular Marine Plants to Natural Blue-Green Light Environments.- Blue Light Effects in Marine Macroalgae.- Blue-Green and Green Light Adaptations on Photosynthetic Activity in Some Algae Collected from Subsurface Chlorophyll Layer in the Western Pacific Ocean.- Organism Index.

181 citations


Journal ArticleDOI
TL;DR: Most cells are unaffected by relatively high concentrations of psoralen photochemistry in the absence of ultraviolet light, and the metabolites of the psoralens have thus far not created a problem.
Abstract: Psoralen photochemistry is specific for nucleic acids and is better understood at the molecular level than are all other methods of chemical modification of nucleic acids. These compounds are used both for in vivo structure analysis and for photochemotherapy since they easily penetrate both cells and virus particles. Apparently, natural selection has selected for membrane and virus penetrability during the evolution of these natural products. Most cells are unaffected by relatively high concentrations of psoralens in the absence of ultraviolet light, and the metabolites of the psoralens have thus far not created a problem. Finally, psoralens form both monoadduct and cross-links in nucleic acid helices, the yield of each being easily controlled by the conditions used during the photochemistry.

178 citations


Journal ArticleDOI
TL;DR: The influence of ultraviolet light, heating, freezing and weathering on the primary feathers from Guillemot and Black Guillemots has been examined in this article, and even within 8 months of exposure variation in mercury concentration due to either loss of mercury or weight loss of the feathers has been found to be less than 10% relative.

Journal ArticleDOI
TL;DR: Depletion of monocytes from the mononuclear cells by double adherence resulted in virtual loss of the generation of 5-lipoxygenase-derived products by the remaining nonadherent cells, supporting the conclusion that the monocytes and not the lymphocytes were the source of LTC4, LTB4, and 5-HETE.

Journal ArticleDOI
01 Dec 1984-Nature
TL;DR: In this paper, the first satellite measurements of electron precipitation by lightning were reported, and the measured energy deposition of these conspicuous lightning-induced electron precipitation (LEP) bursts (∼ 10−3 erg cm−2) is sufficient to deplete the Earth's radiation belts and to alter subionospheric radiowave propagation (≲1 MHz).
Abstract: The broadband very low frequency (VLF, 0.3–30 kHz) radiation from lightning propagates in the Earth–ionosphere cavity as impulsive signals (spherics) and in the dispersive plasma regions of the ionosphere and magnetosphere it propagates as tones of descending or rising frequency (whistlers)1. VLF radio waves propagating in the magnetospheric plasma scatter energetic electrons by whistler-mode wave–particle interactions (cyclotron resonance) into the atmosphere2–6. These electrons, through collisions with the atmospheric constituents, cause localized ionization, conductivity enhancement, visual and ultraviolet light emissions, and brems-strahlung X rays. We have reported previously on the precipitation of energetic electrons from the radiation belts by the controlled injection from the ground of VLF radio waves7,8. Here we report the first satellite measurements of electron precipitation by lightning. The measured energy deposition of these conspicuous lightning-induced electron precipitation (LEP) bursts (∼ 10−3 erg cm−2) is sufficient to deplete the Earth's radiation belts and to alter subionospheric radiowave propagation (≲1 MHz). A one-to-one correlation is found between ground-based measurements of VLF spherics and whistlers at Palmer, Antarctica, and low-altitude satellite (S81-1) measurements of precipitating energetic electrons.

Journal ArticleDOI
TL;DR: It is shown that C proteins with similar characteristics to those in humans are ubiquitous components of hnRNPs in vertebrates and Immunofluorescence microscopy demonstrated that the C proteins are segregated to the nucleus.
Abstract: The C proteins (C1 and C2) are major constituents of the 40S subparticle of heterogeneous nuclear ribonucleoprotein complexes (hnRNPs) (Beyer, A.L., M.E. Christensen, B.W. Walker, and W.M. LeStourgeon, 1977, Cell, 11:127-138) and are two of the most prominent proteins that become cross-linked by ultraviolet light to heterogeneous nuclear RNA (hnRNA) in vivo. Studies are described here on the characterization of the C proteins in vertebrate cells using monoclonal and polyclonal antibodies. Monoclonal antibodies to genuine RNP proteins, including the C proteins, were obtained by immunizing mice with purified complexes of poly(A)+ hnRNA and poly(A)+ mRNA with their contacting proteins in vivo obtained by ultraviolet cross-linking the complexes in intact cells (Dreyfuss, G., Y.D. Choi, and S.A. Adam, 1984, Mol. Cell. Biol., 4:1104-1114). One of the monoclonal antibodies identified the C proteins in widely divergent species ranging from human to lizard. In all species examined, there were two C proteins in the molecular weight range of from 39,000 to 42,000 for C1, and from 40,000 to 45,000 for C2. The two C proteins were found to be highly related to each other; they were recognized by the same monoclonal antibodies and antibodies raised against purified C1 reacted also with C2. In avian, rodent, and human cells the C proteins were phosphorylated and were in contact with hnRNA in vivo. Immunofluorescence microscopy demonstrated that the C proteins are segregated to the nucleus. Within the nucleus the C proteins were not found in nucleoli and were not associated with chromatin as seen in cells in prophase. These findings demonstrate that C proteins with similar characteristics to those in humans are ubiquitous components of hnRNPs in vertebrates.

Journal ArticleDOI
TL;DR: In this paper, the authors described the preparation and optimization of a water-cleavage catalyst consisting of Pt/TiO/sub 2/ (P-25 Degussa) and two different methods were used to prepare the catalyst: impregnation followed by reduction and exchange.
Abstract: This article describes the preparation and optimization of a water-cleavage catalyst consisting of Pt/TiO/sub 2/ (P-25 Degussa). Two different methods were used to prepare the catalyst: impregnation followed by reduction (calcination in certain cases) and exchange. H/sub 2/PtCl/sub 6/ and Pt(NH/sub 3/)/sub 4/(OH)/sub 2/ were used as base materials. The efficiency of the catalyst was tested in relation to its ability to mediate H/sub 2/ evolution for water under UV light. The influence of pH, temperature, concentration of Pt, as well as preparation temperature and time of reduction are described. Characterization by electron microscopy (EM), surface area measurements (BET), diffuse reflectance spectroscopy (DRS), hydrodynamic particle radius R/sub h/, and electrophoresis is carried out. It is shown that metal islands with a particle size below 8 Angstrom deposited onto TiO/sub 2/ agglomerates of 3000 < R/sub h/ < 6000 Angstrom are the most active catalytic species. The fate of oxygen produced by conduction band holes is also investigated.

Journal ArticleDOI
01 Jul 1984-Cell
TL;DR: In the supernatant of UV-treated cells, a heat-labile ammonium sulfate precipitable factor of more than 10 kd was detected which, upon transfer to nonirradiated cells, mimicked UV in the UV-induced synthesis of gene products.

Journal ArticleDOI
TL;DR: The first quantitative measurements of the wavelength dependence of oxygen consumption in systems containing eumelanin and synthetic DOPA melanin are reported, indicating that the major chromophore responsible for oxygen consumption is the same for both kinds of material.
Abstract: — The first quantitative measurements of the wavelength dependence of oxygen consumption in systems containing eumelanin (from bovine eyes) and synthetic DOPA melanin are reported. Consumption of oxygen (considered to be a requirement for immediate pigment darkening) during irradiation of melanins with either visible or ultraviolet light was monitored using a spin probe nitroxide-electron spin resonance spectroscopic approach. From initial rates of oxygen removal, quantum yields have been obtained over a wavelength range from 230 to 600 nm. Eumelanins are moderately effective in promoting oxygen consumption; quantum yields are low for irradiation with visible light, but increase sharply with light of shorter wavelengths. The absolute quantum yield for oxygen consumption is about 0.1% for natural melanin at 320 nm. The action spectrum is similar for both natural and synthetic melanins, indicating that the major chromophore responsible for oxygen consumption is the same for both kinds of material. This chromophore is not the major melanin chromophore responsible for absorption of visible light. The action spectrum also clearly differs from published action spectra for melanogenesis; however, the weak wavelength dependence for visible light is similar to that found for immediate pigment darkening. Catalase decreases the rate of oxygen consumption by 50%, confirming that hydrogen peroxide is the major molecular product of oxygen reduction. A Type I (free-radical) mechanism evidently predominates: D2O and azide are shown to have only minor effects, ruling out any major contribution from a Type II (singlet-oxygen) process to the overall oxygen consumption.

Journal ArticleDOI
TL;DR: In this paper, surface characteristics of ultraviolettreated wood were analyzed by infrared and ultraviolet spectroscopy, and it was shown that ultraviolet-treated wood is rich in carboxylic and carbonyl chromophoric groups and poor in aromatic functional groups.
Abstract: Wood is beautiful but sensitive to light. Because of the chromophoric system at its surface, ultraviolet light cannot penetrate it deeper than 80 μm. Surface characteristics of ultraviolettreated wood were analyzed by infrared and ultraviolet spectroscopy. Analyses of infrared spectra revealed that ultraviolet-treated wood is rich in carboxylic and carbonyl chromophoric groups and poor in aromatic functional groups. Ultraviolet spectral studies suggest that water-soluble low molecular weight fractions of degraded products from the wood surface are mainly derived from lignin. These degradation products contained carbonyl conjugated phenolic hydroxyl groups and had a weight-average molecular weight of about 900, confirmed by gel permeation chromatography.

Journal ArticleDOI
TL;DR: In this paper, the addition of triethylsilane to phenylacetylene or diphenyl-acetylene, catalysed by cis-[RhCl(COD)LMe] or trans-[Rhodium(PPh3)2LMe], proceeds stereoselectively via trans-addition.

Journal ArticleDOI
TL;DR: The ultraviolet-light absorption and fluorescence of Triton X-100 were virtually eliminated by hydrogenation to its reduced cyclohexyl analog, RTX-100.

Journal ArticleDOI
TL;DR: A consideration of all the data strongly suggests that Pyr(6-4)Pyo photoproducts are mutagenic lesions, permitting the conclusion that thymine-thymine cyclobutyl dimers are not the primary cause of ultraviolet light-induced transitions.

Journal ArticleDOI
TL;DR: The induction of carbonic anhydrase activity in Chlamydomonas reinhardtii is examined and the polypeptide responsible for this activity is identified and it is indicated that the bulk of the carbonicAnhydrase is located either in the periplasmic space or is loosely bound to the algal cell wall.
Abstract: We have examined the induction of carbonic anhydrase activity in Chlamydomonas reinhardtii and have identified the polypeptide responsible for this activity. This polypeptide was not synthesized when the alga was grown photoautotrophically on 5% CO2, but its synthesis was induced under low concentrations of CO2 (air levels of CO2). In CW-15, a mutant of C. reinhardtii which lacks a cell wall, between 80 and 90% of the carbonic anhydrase activity of air-adapted cells was present in the growth medium. Furthermore, between 80 and 90% of the carbonic anhydrase is released if wild type cells are treated with autolysin, a hydrolytic enzyme responsible for cell wall degradation during mating of C. reinhardtii. These data extend the work of Kimpel, Togasaki, Miyachi (1983 Plant Cell Physiol 24: 255-259) and indicate that the bulk of the carbonic anhydrase is located either in the periplasmic space or is loosely bound to the algal cell wall. The polypeptide associated with carbonic anhydrase activity has a molecular weight of approximately 37,000. Several lines of evidence indicate that this polypeptide is responsible for carbonic anhydrase activity: (a) it appears following the transfer of C. reinhardtii from growth on 5% CO2 to growth on air levels of CO2, (b) it is located in the periplasmic space or associated with the cell wall, like the bulk of the carbonic anhydrase activity, (c) it binds dansylamide, an inhibitor of the enzyme which fluoresces upon illumination with ultraviolet light, (d) antibodies which inhibit carbonic anhydrase activity only cross-react with this 37,000 dalton species.

Journal ArticleDOI
TL;DR: The results demonstrate that insulin action results in the exposure to the extracellular medium of previously sequestered hexose transporters.

Journal ArticleDOI
TL;DR: It is concluded that chronic hemodialysis patients exhibit defective photoproduction of cholecalciferol, despite normal epidermal content of substrate, 7-dehydrocholesterol.
Abstract: ALLAN I. JACOB,* AŽALAN SALLMAN,* ZENAIDASANTIZ* ANDBRUCE W. HOLLIS'AŽ'Department of Medicine, University of Miami School ofMedicine, Miami, FL 33101, AŽA/brt/iBeach Dialysis Clinic,North Miami Beach, FL 33169 and iDepartment of Nutrition, Case Western Reserve University, Cleveland, OH 44106ABSTRACT The initial step in cholecalciferol (vitamin D3) metabolism is thephoto-conversion of 7-dehydrocholesterol to previtamin D3. This reaction occurs inthe epidermis and requires ultraviolet light. We measured the circulating concentration of vitamin D (ergocalciferol and cholecalciferol), 25-hydroxyvitamin D and1,25-dihydroxyvitamin D in 14 normal white, 9 normal black subjects, and in 9 whiteand 17 black hemodialysis patients. The mean plasma vitamin D in normal whitesubjects was greater than in normal black subjects, 4.01 ±1.02 ng/ml versus 0.96±0.30 ng/ml, respectively (P < 0.05). Plasma 25-hydroxyvitamin D in normalblacks was also less than in normal whites, 17.7 ±1.5 ng/ml versus 31.3 ±3.0 ng/ml,respectively (P < 0.01). In uremie white subjects, plasma vitamin D, 6.7 ±2.6ng/ml, was similar to normal white subjects. However, vitamin D was not detectablein 12 of 17 uremie black subjects and was depressed in the remainder of the group.Following exposure to a single minimal erythema dose of ultraviolet-B irradiation, themaximal increase in plasma vitamin D was depressed in white dialysis patients ascompared to healthy white subjects, 6.3 ±1.9 ng/ml versus 21.3 ±2.8 ng/ml, respectively (P < 0.02). 7-Dehydrocholesterol content was similar in epidermis from site-matched skin of fresh cadavers and white hemodialysis patients, 131 ±23 ng/mgversus 124 ±14 ng/mg skin, respectively. It is concluded that chronic hemodialysispatients exhibit defective photoproduction of cholecalciferol, despite normal epidermal content of substrate, 7-dehydrocholesterol. J. Nutr. 114: 1313-1319, 1984.INDEXING KEY WORDS uremia •vitamin D •photobiologyMajor advances in understanding the of 25-OH-D then occur in various tissues ofmechanisms and biological regulation of which renal tissue is quantitatively the mostvitamin D synthesis have recently been important (10). The effects of chronicachieved, and sensitive assays for plasma uremia on the photoproduction and circu-vitamin D have been developed (1-4). Dur- lating concentration of vitamin D are theing exposure to ultraviolet-B [UV(B), spec- subject of this investigation,trai range 290-320 nm], 7-dehydrocholesterol (7-DHC) in the epidermis is converted MATERIALSAND METHODSto previtamin D3, which slowly undergoesthermal isomerization to cholecalciferol Sterols. [la,2a-3H]D3 (22 Ci/mmol) and(vitamin D3) (5-8). A carrier protein, vita- 25-OH-[26,27-3H]D3 (20 Ci/mmol) weremin D-binding protein, transports theparent compound to the liver for hydroxyla-tion, giving rise to 25-hydroxyvitamin D 27^^teâ„¢^" Ins"'ute°fNutriM°"'Receivedf°rpublication(25-OH-D) (9). Subsequent hydroxylations 'TOwhomreprintrequestsshouldbeaddressed.1313

Journal ArticleDOI
TL;DR: In this paper, it was shown that the mechanisms regulating malignant transformation are different from those regulating DNA repair, sister chromatid exchange, and mutagenesis and may be associated with changes in gene regulation and expression caused by alterations in poly(ADP-ribosyl)ation.
Abstract: Malignant transformation in vitro of hamster embryo cells and mouse C3H 10T 1/2 cells by x-rays, ultraviolet light, and chemical carcinogens was inhibited by benzamide and by 3-aminobenzamide at concentrations that are specific for inhibition of poly(ADP-ribose) formation. These compounds slow the ligation stage of repair of x-ray and alkylation damage but not of ultraviolet light damage. At high concentrations they also inhibited de novo synthesis of DNA purines and DNA methylation by S-adenosylmethionine. The suppression of transformation by the benzamides is in striking contrast to their reported effectiveness in enhancing sister chromatid exchange, mutagenesis, and killing in cells exposed to alkylating agents. Our results suggest that mechanisms regulating malignant transformation are different from those regulating DNA repair, sister chromatid exchange, and mutagenesis and may be associated with changes in gene regulation and expression caused by alterations in poly(ADP-ribosyl)ation.

Journal ArticleDOI
TL;DR: The high-performance liquid chromatography purification procedure devised to isolate cross-linked peptide-oligonucleotide complexes should be of general applicability and should facilitate future structure/function studies on other nucleic acid-binding proteins.

Journal ArticleDOI
TL;DR: A hybrid polypeptide with beta-galactosidase activity was formed when lac mutant cells harboring such plasmids were incubated with low doses of N-methyl-N'-nitro-N-nitrosoguanidine or methylmethane sulfonate and other DNA-damaging agents did not induce the enzyme activity.

Journal ArticleDOI
TL;DR: Aspergillus flavus NRRL 3357 was grown on enriched long-grain rice for 7-10 days to produce aflatoxin B1 (AFB1) as mentioned in this paper.
Abstract: Aspergillus flavus NRRL 3357 was grown on enriched long-grain rice for 7-10 days to produce aflatoxin B1 (AFB1). The quantity of AFB1 in moldy rice was determined by thin-layer chromatography using ultraviolet light. When the dried moldy rice powder was fed to day-old Hubbard X Hubbard broiler chicks in unmedicated feed (AFB1 level 10 ppm) for 8 weeks, there was a profound reduction in weight gain and feed consumption. Chickens fed AFB1 developed severe liver damage, as determined by the concentration of hepatic microsomal cytochrome P-450 and by the activities of microsomal benzphetamine N-demethylase and serum glutamic oxalacetic transaminase. However, activated charcoal, reduced glutathione, cysteine, selenium (as sodium selenite), beta-carotene, and fisetin administered orally considerably reduced the toxicity of AFB1 in the experimental chickens.

Journal ArticleDOI
TL;DR: The induction of breaks in DNA in vitro caused by 334‐nm UV radíation is enhanced by the following compounds (fluence enhancement factors and concentrations used in parentheses): 4‐thiouridine (6.9, 1 mM), 5‐methylamino‐2‐thaviouridine (7.5, 1%) and the oxidized and reduced forms of nicotinamide adenine dinucleotide.
Abstract: — The induction of breaks in DNA in vitro caused by 334-nm UV radiation is enhanced by the following compounds (fluence enhancement factors and concentrations used in parentheses): 4-thiouridine (6.9, 1 mM), 5-methylamino-2-thiouridine (7.5, 1 mM), 2-thiouracil (41.0, 1 mM), riboflavin (14.4.0.1 mM), and the oxidized (6.8, 1 mM) and reduced (3.4, 1 mM) forms of nicotinamide adenine dinucleotide. Anoxia and diazobicyclo(2.2.2)octane reduce the number of DNA breaks caused by 334-nm radiation plus 4-thiouridine by 70 and 76%, respectively.

Journal ArticleDOI
TL;DR: A 1,4‐dihydroypyridine arylazide photoaffinity ligand, [3H]azidopine (50.6 Ci/mmol), has been synthesized and it is suggested that it is photoincorporated into a subunit of the putative Ca2+ channel.