bluuebunny/crossref_metadata_2025 huggingface dataset:
A SURVEY OF IN VIVO PHOTODYNAMIC ACTIVITY OF XANTHENES, THIAZINES, AND ACRIDINES IN YEAST CELLS
Authors: Ito Takashi , Kobayashi Katsumi
Published: January 2008

Abstract. In view of the recent interest in the possibility of a singlet oxygen mechanism playing an important role in photodynamic action, a number of different types of dyes were surveyed with respect to cell inactivation and induction of genetic changes in yeast cells. These comprise three xanthene dyes, three thiazine dyes, three acridine dyes and ethidium bromide. Rhodamine B in the first group and methylene blue in the second group were inactive under the present conditions. Both were found to be non‐penetrable into the cell. However, since toluidine blue is active, non‐penetrability is not a determining factor in photodynamic action. Ethidium bromide was inactive under the present conditions, even though it was penetrable into the cell. The survey showed that the dye must be bound to DNA in order to be active in the induction of a genetic change (gene conversion). All dyes which were active in either inactivation or induction or both were modified in their effectiveness both by the addition of N‐3 (suppression) and in deuterated medium (enhancement), indicating that the sensitization mechanism involves singlet oxygen. The deuterium effect was generally observable to a lesser extent in the in vivo situation than in vitro, in particular for genetic changes by profiavine and acriflavine in which the sensitizer binds to DNA.
THE PHOTOCHEMISTRY OF RIBOFLAVIN—VI. THE PHOTOPHYSICAL PROPERTIES OF ISOALLOXAZINES
Authors: Moore William M. , McDaniels John C. , Hen John A.
Published: January 2008

Abstract— Many of the photophysical properties of riboflavin and several other N‐10 substituted isoal‐loxazines have been measured and these include: quantum yields of fluorescence at 77 K and 298 K, φ, quantum yields of phosphorescence at 77 K, φP, lifetimes of the triplet state by electron spin resonance and phosphorescence at 77 K, φp,. and the quantum yield of intersystem crossing. φisc. For riboflavin in an alcoholic matrix at 77 K the limiting values were: φJ= 0.32, φP= 0.007, φp= 0.20s and φisc= 0.7. At 298 K, φf for riboflavin in water and alcohol were 0.25 and 0.32, respectively. The results for the photophysical processes are compared with several photochemical processes known to involve the triplet state of riboflavin in aqueous solution. It is concluded that the φisc decreases from 0.7 in alcohol to 0.6 in water at 298 K.
RESOLUTION OF THE FLUORESCENCE EXCITATION SPECTRUM OF INDOLE INTO THE 1La AND 1Lb EXCITATION BANDS*
Authors: Valeur Bernard , Weber Gregorio
Published: January 2008

Abstract— The fluorescence excitation spectrum and the excitation polarization spectrum of indole in propylene glycol were measured at — 58°C, after selecting by optical filters the emission originating from the 1La electronic level. From the analysis of these spectra, the excitation spectrum was resolved into the 1La and 1La excitation bands. A similar resolution of the excitation spectrum of tryptophan is given. This method can also be applied to the resolution of the emission spectrum in cases of dual emission.
AN ACTION SPECTRUM OF PHYTOCHROME BINDING TO A SUBCELLULAR FRACTION OF MAIZE COLEOPTILES
Authors: Fuad Noha , Yu Richard
Published: January 2008

Abstract— An action spectrum was constructed for the photo‐induced pelletability of phytochrome in excised coleoptiles of etiolated maize seedlings. It closely resembled the absorption spectrum of purified phytochrome in the P, form as reported in the literature. The spectral dependence of phytochrome pelletability effected by sustained irradiation (4 h) was also determined and it appeared remarkably similar to the high irradiance response (HIR) action spectrum reported for the inhibition of lettuce hypocotyl lengthening. The induction action spectrum was held to support the conclusion that phytochrome itself is the photoreceptor for its own binding to the subcellular fraction of maize coleoptiles and that the binding phenomenon is an early, if not the first, physiological consequence of irradiation. Also a modified version of Hartmann's interpretation of the high irradiance response was given.
ELECTRON MOTIONS IN AQUEOUS SYSTEMS—A SURVEY*
Authors: Grossweiner L. I.
Published: January 2008

Abstract— This paper reviews current experimental and theoretical information about the immediate fate of electrons generated in aqueous systems by ionizing radiation or photolysis of solutes. The applications of spur diffusion theory to pulse radiolysis and flash photolysis results are considered, with brief accounts of related developments in connection with time‐dependent rate constants, the radiation sensitivity of large biological targets, and long‐range electron interactions including tunneling.
PROTECTION OF CHLOROPHYLL a BY CAROTENOID FROM PHOTODYNAMIC DECOMPOSITION
Authors: Koka Prasad , Song Pill‐Soon
Published: January 2008

Abstract— The order of inhibition of the photooxidation of chlorophyll a in ethanol and ethanol‐benzene is as follows: β‐carotene, α‐tocopherol, benzoquinone, DABCO, menadione, cholesterol and KI. The quenching of singlet oxygen by β‐carotene occurs by a collisional quenching mechanism with a diffusion‐controlled rate of 1.7 × 1010M‐1 s‐1. Photodecomposition of Chi a is faster in ethanol‐D2O than in ethanol‐H2O. Photoirradiation (660 nm) of the peridinin‐Chl a‐protein complex, a photosynthetic light‐harvesting pigment isolated from marine dinoflagellates, did not show any photo‐decomposition of its Chi a in H2O or D2O, even after an extended period (12 h) of irradiation. However, the carotenoid, peridinin, in the photosynthetic antenna pigment was photobleached (ca. 10%) during the irradiation. We conclude that the singlet oxygen formed as a result of the Chi photosensitization is immediately quenched by the low‐lying triplet state of four peridinin molecules (per Chl a) bound within the same protein crevice. The carotenoid thus effectively protects Chl a from photodynamic damage, providing a direct proof for the protective role of carotenoids in the photosynthetic pigment complex.
THE ROLE OF SINGLET OXYGEN IN THE PHOTOOXIDATION OF POLYMERS
Authors: Rabek Jan F. , Rånby Bengt
Published: January 2008

Abstract— This paper is a critical review of the singlet oxygen oxidation of polymers in solid state and in solution, referring in particular to polydienes, polystyrene and polyvinyl chloride). The singlet oxygenation of polydienes resulted in formation of allylic hydroperoxide groups with shifted double bonds, according to the “ene”‐type process. The singlet oxygenation of polystyrene and polyvinyl chloride) occurs only when the new double bonds are formed in these polymers. During dye‐photosensitized singlet oxygenation of polydienes in methanol‐benzene solution, a very rapid decrease in the molecular weight was observed. For the chain‐scission which occurs, not only singlet oxygen but several intermediates such as radicals, bi‐radicals and cation‐radicals which are formed during light fading of dyes are responsible. At the end of this paper a short review appears which has been focused on the quenching behavior of stabilizers, particularly interactions with singlet oxygen.
ADDITION OF OXYGEN AS A DIAGNOSTIC TEST IN MERCURY 6 (3P1) PHOTOSENSITIZATION
Authors: Maré George R. De
Published: January 2008

Abstract— Mercury in contact with oxygen is rapidly removed from the gas phase when irradiated with the 253.7 run resonance line. The final, steady‐state concentration of mercury depends on the total pressure, the mol % of oxygen, and the presence (or absence) of mercury droplets in the reaction cell. The effect of oxygen on the mercury photosensitized formation of allene from methylenecyclobutane and trans‐2‐butene from cis‐2‐butene at room temperature was investigated. After correction for competitive quenching, collisional deactivation of the excited methylenecyclobutane, and decreased absorption (due to mercury depletion), the maximum decrease in the allene yield was only 12.3%. This decrease could be caused by the reaction of oxygen atoms or ozone with the product allene. In most of the experiments with mercury‐oxygen‐cis‐2‐butene mixtures, the corrected quantum yield of the trans‐isomer is unchanged from the yield in the absence of oxygen (0.50). Thus oxygen cannot be used to detect the participation of triplet state molecules in mercury photosensitized reactions.
O2‐ AND HOST DEFENSE: THE PRODUCTION AND FATE OF O2‐ IN NEUTROPHILS*,§
Authors: Tauber Alfred I. , Babior Bernard M.
Published: January 2008

Abstract— The neutrophil is a circulating cell whose function is to find, ingest and destroy invading microorganisms. Among the weapons used by this cell against its target is a series of powerful oxidizing agents produced by the partial reduction of oxygen. Generation of these oxidizing agents is initiated when the neutrophil encounters its target. This encounter activates a flavoenzyme, dormant in resting cells, which catalyzes the reduction of oxygen to O2‐ using NADPH as the electron donor. The dismutation of O2‐ either spontaneously or under catalysis by superoxide dismutase, then gives rise to H2O2, a compound which is used in combination with Cl‐ and myeloperoxidase to provide an exceedingly powerful antimicrobial system. O2‐ also serves as a precursor of OH, another powerful oxidant which may be employed by the neutrophil as an antimicrobial agent. Singlet oxygen may also be formed in neutrophils.
PHOTOINDUCED ELECTRON TRANSFER REACTIONS IN PHTHALOCYANINE DISPERSIONS
Authors: Harbour John R. , Hair Michael L.
Published: January 2008

Abstract— The photochemistry of phthalocyanine particles suspended in a fluid has been investigated. In alcoholic media, these particles were shown to be capable of reducing benzoquinone and oxidizing hydroquinone. In aqueous media the light induced formation of superoxide was detected. This reaction could be substantially enhanced by addition of EDTA. The role of surfactant in the photoproduction of superoxide is associated with the charge acquired by the particle as a result of the surfactant used. These results can be explained in terms of the band model for semiconductors where band bending by surfactant molecules is invoked. Such studies have relevance to photoevents occurring in photosynthesis, photocatalysis and to the types of solar energy conversion systems where a photoactive semiconductor interfaces with an aqueous medium.
SUPEROXIDE AND PEROXIDASE‐CATALYSED REACTIONS. OXIDATION OF DIHYDROXYFUMARATE, NADH AND DITHIOTHREITOL BY HORSERADISH PEROXIDASE*
Authors: Halliwell Barry , Rycker Johann de
Published: January 2008

Abstract— When oxidizing NADH or dihydroxyfumarate, horseradish peroxidase exists mainly as compound III, which is formed by a reaction between O‐2 and the enzyme. Certain phenols stimulate peroxidase‐catalysed oxidation of NADH or dihydroxyfumarate, apparently because they bring about the breakdown of compound III to active enzyme. Superoxide dismutase and catalase, added at any time during the reaction, inhibit dihydroxyfumarate oxidation by peroxidase. This is attributed to generation of the dihydroxyfumaryl radical during H2O2‐dependent oxidation of dihydroxyfumarate by peroxidase. This radical reduces O2 to O‐2, which can then react with more dihydroxyfumarate. Superoxide dismutase added during the course of the reaction does not inhibit NADH oxidation by peroxidase, since O‐2, although generated in the reaction mixture, reacts only slowly with NADH. Lactate dehydrogenase or Mn2+ stimulate NADH oxidation by peroxidase because they catalyse a reaction between NADH and O‐2. Oxidation of NADH by peroxidase in the presence of certain phenols and Mn2+ is very rapid, and requires both H2O2 and O‐2. O‐2 also seems to be necessary to initiate NADH oxidation by peroxidase. Aromatic compounds are hydroxylated by a mixture of peroxidase and dihydroxyfumarate. Hydroxylation is prevented by superoxide dismutase or by scavengers of the hydroxy radical (.OH). O‐2 is insufficiently reactive to hydroxylate aromatic rings directly and so may give rise to .OH, which is the true hydroxylating species. Hydroxyl radical probably does not arise by the Haber‐Weiss reaction. H2O2, but not O‐2, is involved in the oxidation of thiol compounds by peroxidase.
MECHANISM OF OXYGEN DETOXIFICATION IN NEONATAL RAT LUNG TISSUE
Authors: Autor Anne P. , Stevens Jeffrey B.
Published: January 2008

Abstract— Pulmonary macrophages obtained from neonatal rats contain approximately four times the activity of cyanide resistant superoxide dismutase and catalase compared with the cells from adult animals. The activity is highest immediately after birth and diminishes with age until the minimum level is reached at approximately 3 weeks of age. Superimposed upon this change in basal activity is the capability of neonatal cells to synthesize additional cyanide resistant superoxide dismutase and catalase when either the animals or isolated pulmonary macrophages are exposed to 95–100% oxygen. The inductive effect begins at 2–3 days after birth, peaks at 10 days, and disappears at approximately 15 days after birth. In contrast to adult rats, neonatal rats are extremely resistant to the toxic effects of oxygen. If, however, the oxygen mediated increase in both enzymes is prevented or the maximum effective pulmonary macrophage number is diminished in test animals, these animals become vulnerable to toxic effects of oxygen exposure, observed by gross and histologic examination of lung tissue, in a manner similar to adult animals. These data indicate that both cyanide‐resistant superoxide dismutase and catalase may be part of the endogenous defense mechanisms which provide neonatal rats with an exceptional resistance to oxygen toxicity.
THE FORMATION OF FREE RADICALS AND THE CONSEQUENCES OF THEIR REACTIONS IN VIVO
Authors: Pryor William A.
Published: January 2008

Abstract— Mechanisms for the initiation of free radical reactions in vivo are reviewed, including ozone and 1O2 reactions, radiation, one‐electron transfer processes, and enzymatic reactions. The roles that radical reactions might play in aging processes and in carcinogenesis are discussed.
THE EFFECT OF OXIDANT INJURY ON THE LYMPHOBLASTIC TRANSFORMATION OF HUMAN LYMPHOCYTES*
Authors: Jr Arthur L. Sagone , Ramps Susan , Campbell Robert
Published: January 2008

Abstract— We have studied the effect of oxidant injury on the lymphoblastic transformation and glucose metabolism of human lymphocytes. Lymphocyte cultures were incubated with xanthine oxidase and xanthine, an enzyme system known to generate several highly reactive oxygen compounds. Lymphoblastic transformation to phytohemagglutinin was quantitated by the stimulation of DNA synthesis as indicated by the 3H‐thymidine uptake of the cultures at 3 days.

The lymphoblastic transformation of cultures incubated with the enzyme system was significantly impaired compared to controls. These cultures also failed to demonstrate the burst of glucose metabolism characteristic of transforming cells. To firmly establish that the effect of the enzyme system on lymphoblastic transformation was related to reactive oxygen molecules, the effect of several scavengers was studied. Cultures supplemented with catalase were almost completely protected against the effect of the enzyme system. In contrast, cultures supplemented with superoxide dismutase, mannitol and azide. scavengers of superoxide, hydroxyl radicals, and singlet oxygen, respectively, were not protected. These data indicate that the functional capacity of human lymphocytes can be impaired in vitro by exposure to hydrogen peroxide.
SPECTROPHOTOMETRIC STUDY OF DIENESTROL PHOTOISOMERIZATION
Authors: Doyle T. D. , Benson W. R. , Filipescu N.
Published: January 2008

Abstract— Photolysis of synthetic estrogen dienestrol resulted in formation of a 4a,4b‐dihydrophenanthrene, a rare example of a stable intermediate of the classical stilbene → phenanthrene photocyclization. Time‐lapse spectrometric investigation suggested an initial cis‐trans isomerization in the dimethylbuta‐dime moiety of dienestrol followed by a photochemical [1, 51 sigmatropic proton transfer which converted the two cross‐conjugated p‐hydroxystyrene halves into a vinyl‐stilbene. A subsequent electrocyclic ring‐closure in an electronically excited state generated a cyclic nonaromatic heptenediol. This last photoproduct tautomerized rapidly in the dark to a stable, crystalline, tricyclic pentenedione. The final diketone product is an example of a 4a.4b‐dihydrophenanthrene self‐stabilized by a double ketoenol tautomerism. The three sequential photoisomerizations of dienestrol are made possible by a fortuitous coincidence of steric and orbital symmetry requirements.
PHOTOMODULATION OF AZOALDOLASE ACTIVITY
Authors: Montagnoli Giorgio , Montt Sandra , Nannicini Luciano , Giovannitti Maria Piera , Ristori Maria Giovanna
Published: January 2008

Abstract— Rabbit muscle aldolase, modified by azo groups covalently bound to cysteinyl residues 237 and 287, shows activation of the fructose‐1,6 diphosphate cleavage reaction at 30T, after preirradiation with visible light. When the light treatment is carried out under an atmosphere of Ar to avoid oxidation, there is a reversible diminution of the Michaelis‐Menten constant, with no change in the turnover number. The direct effect of the light is the E → Z geometric isomerization of the azochromophore; thereafter the Z isomer is thermally converted to the more stable E isomer. Both regulation at the level of the enzyme‐substrate interaction and the involvement of the geometry of the chromophore have been demonstrated. The substrate, added to azoaldolase in the dark, causes E to Z isomerization of part of the extrinsic protein chromophores leading to a different isomeric composition at the thermal equilibrium. This result is consistent with higher binding energy of the enzymesubstrate complex when the modified enzyme contains azo chromophores in the Z configuration, as compared with the same chromophores in the E configuration. Azoaldolase has been discussed as a model for direct photoregulation of enzyme activity at the level of enzyme‐substrate interaction.
ENERGY TRANSFER AND PHOTOOXIDATION KINETICS IN REACTION CENTERS ON THE PICOSECOND TIME SCALE
Authors: Moskowitz E. , Malleyt M. M.
Published: January 2008

Abstract— Picosecond 530 nm actinic and 1242 nm probe light pulses have been used to measure the kinetics of energy transfer and photooxidation in Rhodopseudomonas sphaeroides R‐26 reaction centers. The energy transfer rate between bacteriopheophytin and the bacteriochlorophyll dimer is 1.0 ± 0.3 ± 1011s‐land photooxidation of the dimer occurs within 5 ps after the dimer reaches the first excited singlet state. Using these parameters in a simple model we are able to explain the odd result that the number of reaction centers oxidized by a saturating 530 nm actinic picopulse is only 60% of the number oxidized by a saturating CW light source.
BLUE‐LIGHT INDUCED DEVELOPMENT OF CHLOROPLASTS IN ISOLATED SEEDLING ROOTS. PREFERENTIAL SYNTHESIS OF CHLOROPLAST RIBOSOMAL RNA SPECIES
Authors: Richter Gerhard , Dirks Werner
Published: January 2008

Excised roots of pea seedlings (Pisum sativum var. “Alaska”) cultured in a synthetic medium under sterile conditions exhibit differentiation of functional chloroplasts from leucoplasts when irradiated with blue light (350–550 nm). This transition is a relatively slow process; nevertheless, the chloroplasts formed in blue light compare very well to leaf chloroplasts as far as microstructure and photosyn‐thetic activities are concerned.

Apparently certain activities of the apical meristem are mandatory in bringing about a transition from leucoplasts to chloroplasts in blue light. After short‐time labelling with [jH]uridine the synthesis of plastid ribosomal RNA (rRNA) was studied either during irradiation with blue and red light (600–700 nm), respectively, or in darkness. Polyacrylamide gel electrophoresis revealed that in blue light the synthesis of specific chloroplast rRNA species with molecular weights of 1.1 × 106 and 0.56 × 106 daltons is markedly stimulated. In contrast, in dark cultured roots these RNA species were synthesized to a limited extent only whereas the cytoplasmic rRNA species of 1.3 × 106 and 0.7 × 106 daltons molecular weight were preferentially formed. The same holds true for roots irradiated with red light.
BLUE LIGHT EFFECT ON CHLOROPHYLL FORMATION IN CHLORELLA PROTOTHECOIDES
Authors: Oh‐Hama Tamko , Hase EIJI
Published: January 2008

The effectiveness of monochromatic light on chlorophyll formation over a range of 420–80 nm was examined in the regreening cells of Chlorella protothecoides in the presence of chloro‐phenyl dimethylurea (CMU). An action spectrum showed two maxima with a minimum near 450 nm. At the most effective wavelength examined (444 nm), 0.2 W. m ‐2 was sufficient for half saturation. The activity of 5‐aminolevulinic acid (ALA) production was examined in the greening cells under irradiation with white, blue and red light. The activity was always limited by availability of substrate, especially in the case where the greening cells were incubated with cycloheximide or transferred to darkness. Decay of the activity in these cases was delayed by provision of organic compounds such as glycine, pyruvate or glucose. The effectiveness of blue light on ALA* production observed in the presence of CMU was inferred to be brought about by the increased availability of endogenous substrates.
EVIDENCE FOR PHYTOCHROME CONTROLLED ENDOMITOSIS AND CELL ELONGATION IN PISUM SATIVUM EPICOTYLS
Authors: Oostveldt P. Van , Boeken G. , Parus R. Van
Published: January 2008

Elongation and endomitosis were studied in the epicotyl cortex cells of germinating seeds of Pisum sativum cv. Rondo.

One min of red light per 24 h is sufficient to fully inhibit endomitosis. Terminal far‐red irradiation can reverse the red effect to the level established by far‐red light alone. This justifies the conclusion that phytochrome is involved in the regulation of endomitotic DNA replication. Since far‐red light alone inhibits endomitosis to about 50%, we conclude that very low levels of Pfr are required to influence the endomitotic cycle.
MULTISITE TOPOGRAPHIC MICROFLUOROMETRY OF INTRACELLULAR AND EXOGENOUS FLUOROCHROMES*
Authors: Kohen E. , Kohen C. , Hirschberg J. G. , Wouters A. , Thorell B.
Published: January 2008

Abstract. Microspectro fluorometry combined with microinjection of metabolites allows the monitoring of pathways regulating the energy metabolism, biosynthetic or metabolizing activity of the intact living cell. The topographic scan of ˜ 100–150 adjacent regions within a cell or the spectral scan of fluorescence from a single cell region is completed within 60 ms. The in situ activity of intracellular enzymes and substrate concentration vs rate relationships are derived from the kinetic analysis of transients (e.g. NAD(P) ⇄ NAD(P)H) elicited by sequential injections with increasing doses of substrate (e.g. glucose‐6‐P, 6‐phosphogluconate). A method of approximation is used to predict the non‐linear behavior of whole biochemical systems (e.g. the sum of reactions involved in NAD(P) reduction‐reoxidation transients). Approximation to power law kinetics is validated by prediction of system behavior over a 10–100 fold variation in the input concentration of substrate.

The NAD‐dependent glycolytic chain (faster rise kinetics) and NADPH‐dependent shunt pathway (slower rise kinetics) are triggered optionally, by enhanced demand for degradation, synthesis or metabo‐lization of exogenous compounds (hydrocarbons, aflatoxins). Compartmentation of NAD(P) pathways is suggested by differences in the reoxidation of cytoplasmic vs nuclear NAD(P)H. The intercellular transfer of molecules can be evaluated by microinjection of fluorescent tracers.

The difference spectra ΔIF due to microinjection of substrate are resolved in terms of bound vs free NAD(P)H (with differentiation of other endogenous and exogenous fluorochromes).

On the basis of the above, a tentative scheme of intra‐ and intercellular dynamics can be developed.
GENERATION OF SUPEROXIDE ANION WITH A PHOTOREDUCED PHENOXAZINE DERIVATIVE
Authors: Nishikimi Morimitsu , Yamada Hiroshi , Yagi Kunio
Published: January 2008

Abstract. 1‐Hydroxy‐5‐oxo‐5H‐pyrido [3,2a] phenoxazine‐3‐carboxylic acid was found to be reduced when it was irradiated with visible light in the presence of certain electron donors such as tetramethyl ethylenediamine and reduced glutathione. Upon illuminating this compound with either of the above electron donors under aerobic conditions, the coexisting nitroblue tetrazolium was reduced. The reduction was inhibited by superoxide dismutase, which indicated that superoxide anion was generated during the photoinduced reaction.
THE EFFECTS OF FAR ULTRAVIOLET RADIATION ON RESPIRATION AND CATION ACCUMULATION BY ISOLATED MITOCHONDRIA OF PHASEOLUS VULGARIS
Authors: Roy R. M. , Abboud S.
Published: January 2008

Abstract. The respiration rates and respiratory control ratios of isolated bean mitochondria have been measured following exposure to 0, 150, 300 and 900 J/m2 of far UV radiation (190–300 nm) from a mercury vapour light source with 90% total radiant intensity at 254 nm. Loss of respiratory control occurred at 150 J/m2 and inhibition of respiration was significant at the highest exposure dosage. The uptake of both 45Ca and 85Sr have been measured following a 10min incubation of isolated mitochondria with 2 mM cation. Significant decreases in cation accumulation were observed following exposure to 900 J/m2. The effect seemed to be associated with loss of active transport of the ions as a result of respiratory uncoupling or reduced electron transport. There was no significant effect of storage on respiration or ion transport nor was there any indirect effect of irradiated suspending medium on mitochondria.
APPLICATION OF PHOTOSENSITIVE DEVICES TO BIOLUMINESCENCE STUDIES
Authors: Reynolds George T.
Published: January 2008

Abstract—A brief review is given of some results obtained by the application of image intensification to studies of bioluminescence. The system consists of an image intensifier placed at the output of a suitable microscope., so that the image from the microscope falls on the intensifier cathode. The photon gain of the intensifier can be varied from a few thousand to one million. The output of the intensifier is recorded either on film or, in most applications to date, by means of a TV vidicon. The TV system permits display on a monitor in real time and simultaneous recording on magnetic tape for subsequent playback and analysis. It also provides time resolution for dynamic studies. Results are summarized for in vivo observations on Noctiluca miliaris, Obelia, Renilla, and Mnemiopsis leidyi. Utilization of the luminescence of aequorin in the presence of Ca2+ has been directed to observations on amoebae and the egg of the Medaka fish.

Studies at the molecular level have been made by means of the spectral distribution of the output light. In these, the output of a fast input lens grating spectrometer is focused on the image intensifier cathode. Thus the entire visible spectrum of an in vivo bioluminescent flash can be intensified and recorded on film by photographing the output. The film is then analyzed by means of a digitized densitometer, and a computer program corrects the observed spectrum for system non‐linearities and non‐uniformities. In this way, the in vivo spectra of 15 bioluminescent species have been recorded.
SENSITIZED PHOTOOXIDATION OF WOOL BY FLUORESCENT WHITENING AGENTS. A DIRECT SPECTRAL STUDY
Authors: Leaver I. H.
Published: January 2008

Abstract—A fluorescence spectral study has been made of the photochemical behaviour of two types of fluorescent whitening agents, a naphthotriazolylstilbene and a bistriazinylaminostilbene, in single fibres of wool. The photodecomposition of each molecule of the naphthotriazolylstilbene is accompanied initially by the photooxidation of up to 7 residues of trp in the fibre. Amino acid analyses show that his and met residues are also photooxidized. Inhibition of the photooxidation of these amino acids by sodium azide suggests that singlet oxygen is involved in the reaction.
PROFLAVINE PHOTOSENSITIZATION OF DOUBLE AND SINGLE STRANDED DNA: EPR STUDY OF THE EFFECT OF VARIOUS SULPHUR‐CONTAINING SUBSTANCES
Authors: Piette Jacques , Calberg‐Bacq Claire‐M. , Vorst Albert Van de
Published: January 2008

Abstract—The proflavine‐mediated photosensitization of both double‐stranded calf thymus and single‐stranded DNA from bacteriophage φ× 174 was followed in terms of the induction of free radicals in frozen solutions by EPR measurements in the presence of oxygen. The effect of the addition of various sulphur‐containing substances to the proflavine DNA mixtures was studied and quantitatively expressed for definite amounts of proflavine bound to both DNAs.

Upon irradiation with visible light, RS radicals were observed in the presence of these sulphur‐containing substances. Some of them caused a decrease in the amount of peroxide radicals normally induced in the photosensitized DNA. This decrease appeared to be linked to the property of the compounds to interact with DNA in such a way that they modify the binding of proflavine to DNA.

Cysteine, cysteamine, cystamine and cystine, protect calf thymus DNA against the “proflavine and light” free radical induction by 55, 58, 64 ahd 62% respectively. φ× 174 single‐stranded DNA is also protected by the addition of cysteamine and cystamine, although to a lesser extent than calf thymus DNA (35%). These protection factors were measured under conditions where strong binding of the dye to the DNA was predominant.
IMPACT OF ENHANCED SIMULATED SOLAR ULTRAVIOLET RADIATION UPON A MARINE COMMUNITY
Authors: Worrest Robert C. , Dyke Henry Van , Thomson Bruce E.
Published: January 2008

Abstract—There is evidence to indicate that an increased exposure to solar radiation in the UV‐B region (specifically, 290–320 nm) may occur as a result of anthropogenic degradation of stratospheric ozone. The fact that present levels of solar UV radiation can detrimentally affect marine organisms led to experiments to quantify the impact of increased UV radiation upon a marine community. Two 720–l seawater chambers (continuous flow‐through design) were exposed to simulated solar UV radiation. Fluorescent sunlamps filtered by a 290 nm cutoff filter (a 0.13 mm thickness of cellulose triacetate film) were used as the radiation source. Utilization of three different weighting factors for the spectral irradiances at the surface of the chambers yielded differences of 18%, 35% and 40% in biologically effective fluence rate between the two chambers. Analysis of attached forms of algae at various depths demonstrated that a surface exposure of 1.4W/m2 in the 290–315nm waveband as contrasted with the chamber receiving a surface exposure of 1.0W/m2 resulted in depressed Chl a concentrations, reduced biomass, increased autotrophic indices, and decreased community diversity. These results indicate a potential for adverse effects of increased solar UV‐8 radiation: decreased community diversity, community structure shifts, and decreased productivity.
RANDOM DISTRIBUTION OF HIGHLY REPETITIVE AND INTERMEDIATE FREQUENCY MOUSE L‐929 CELL DNA SEQUENCES SYNTHESIZED AFTER UV LIGHT EXPOSURE
Authors: Meltz Martin L. , Whittam Nancy Jo , Thornburg William H.
Published: January 2008

Abstract— The DNA precursor 3H‐thymidine incorporation rate (dpm/pg DNA) in mouse L‐929 cells decreases immediately after exposure to UV light. This decrease is initially dose dependent, but at exposures greater than 22.5 J/m2 appears to be radio‐resistant. This was not explained by measurements of uptake of 3H‐thymidine into the acid soluble pool (dpm/pg DNA). The radio‐resistant incorporation amounted to approximately 35% of the control rate. DNA reassociation (“C0T”) studies were performed with DNA labeled with 3H‐thymidine immediately after exposure of L‐929 cells with a dose of UV resulting in radio‐resistant incorporation to determine whether this radio‐resistant incorporation was occurring in sequences of a particular repetitious frequency. These studies, performed in the highly repetitive to intermediate range, showed that the radio‐resistant incorporation was occurring in DNA of all classes of repetitious frequency. DNA synthesized at different times after UV exposure, during the period when post‐replication repair can occur, was similarly labeled for short intervals and isolated. The DNA reassociation studies showed that this DNA synthesis was also of all classes of repetitious frequency.
PHOTOPHOBIC BEHAVIORAL RESPONSES OF EUGLENA IN A LIGHT INTENSITY GRADIENT AND THE KINETICS OF PHOTORECEPTOR PIGMENT INTERCONVERSIONS*
Authors: Creutz C. , Colombetti G. , Diehn B.
Published: January 2008

Abstract— Accumulation of Euglena gracilis in small illuminated regions called light traps is due to a phobic response to the diminished light intensity at the boundary of the region. The rate of such accumulation of cells was measured as functions of both the light intensity within the trap and the change of intensity at the boundary of the trap. The initial rate of accumulation of a population of cells was taken to be a direct measure of the phobic response of a single typical cell. The data indicate that the strength of the behavioral response in a single cell may be described as being proportional, to the rate of change of the amount of photochemically active form of a photoreceptor pigment molecule which can exist in two predominant forms.
A METHOD FOR MEASURING PHYTOCHROME IN PLANTS GROWN IN WHITE LIGHT
Authors: Jabben Merten , Deitzer Gerald F.
Published: January 2008

Abstract— Quantitative spectrophotometric measurement of phytochrome in plants grown for relatively long periods of time in white light is not possible due to the presence of chlorophyll. A method is described that prevents the accumulation of chlorophyll permitting such direct spectrophotometric measurement in light‐grown tissue. Oat seedlings grown in the presence of the herbicide San 9789† (Norflurazon) for 6 days in constant light have considerably less chlorophyll than etiolated seedlings exposed to 1 min of light. Phytochrome concentrations measured in vivo and in vitro in these herbicide‐treated plants were found to be about 2% of the level in etiolated tissue.
ORIENTATION OF CHLOROPHYLLS IN LIQUID CRYSTALS
Authors: Journeaux Roger , Viovy Roger
Published: January 2008

Abstract— Chlorophyll derivatives can be oriented in a liquid crystal matrix. The temperature and angular dependence of the absorption spectra are studied with polarized light. From these results we can deduce the orientation of the molecules of dye in the liquid crystal. The deconvolution of the Soret band also allows us to assign to the different components their related transition moments.
FLUORESCENCE KINETICS OF SPINACH CHLOROPLASTS MEASURED WITH A PICOSECOND OPTICAL KERR GATE
Authors: Pellegrino F. , YU W. , Alfano R. R.
Published: January 2008

Abstract. An overview of the reported chlorophyll a fluorescence lifetimes from green plant photosystems is presented and the problems encountered in the measurement of fluorescence lifetime using two currently available picosecond techniques are discussed.

The fluorescence intensity of spinach chloroplasts exposed to 10 ps flashes was measured as a function of time after the flash and wavelength of observation by the ultrafast Kerr shutter technique. Using a train of 100 pulses separated by 6ns and with an average photon flux per pulse of ˜2 times 1014 photons/cm2, the fluorescence intensity at 685 nm (room temperature) was found to decay with two components, a fast one with a 56 ps lifetime, and a slow one with a 220 ps lifetime. The 730 nm fluorescence intensity at room temperature decays as a single exponential with a 100 ps lifetime. The 730 nm fluorescence lifetime was found to increase by a factor of 6 when the temperature was lowered from room temperature to 90 K while the lifetime of 685 and 695 nm fluorescence were unchanged. At room temperature, the fast and slow components at 685 nm are attributed to the emission from pigment system I (PS I) and PS II, respectively. It is likely that the absolute values of lifetimes, reported here, may increase if single ps low intensity flashes are used for these measurements.
PICOSECOND FLUORESCENCE AND ELECTRON TRANSFER IN PRIMARY PHOTOSYNTHETIC PROCESSES
Authors: Rubin Andrew B.
Published: January 2008

Abstract. Under conditions that drive the reaction centers (RC's) into the “closed” state, the lifetime (T) of the fluorescence emitted by antenna molecules increases from 80 to 200 ps in PS I, from 300 to 600 ps in PS II, and from 200 to 500 ps in bacterial chromatophores. In Rhodopseudomonas sphaeroides strain 1760‐1, the decay curve for fluorescence from the RC's has a component with T2= 15 ps due to the bacteriochlorophyll of the RC, and a second component with T2= 250 ps due to bacteriopheophytin.

Data on electron transfer at low temperatures and under different redox conditions are analyzed. along with the ps fluorescence kinetics. The hypothesis is discussed that electron transfer in RC's is coupled to conformation changes in the interacting molecules.
PROFLAVIN CATALYZED PHOTOPRODUCTION OF HYDROGEN FROM ORGANIC COMPOUNDS
Authors: Krasna Alvin I.
Published: January 2008

Abstract— Methyl viologen was reduced by EDTA and other organic compounds when aqueous solutions of these compounds were irradiated near 440 nm in the presence of catalytic quantities of proflavin. The photoreduced methyl viologen was readily oxidized in the dark by the enzyme hydrogenase or platinum asbestos. When the entire reaction was run in the light with hydrogenase or platinum, continuous production of hydrogen was observed. The yield of hydrogen was approximately stoichiometric to the EDTA present establishing that methyl viologen and proflavin were acting catalytically. To establish the structural requirements of the electron donor, eighty compounds were tested at seven pH values between 4 and 10. Of these, twenty served as electron donors for the photoproduction of hydrogen. The effective donors contained either a secondary or tertiary nitrogen atom with one or more carboxymethyl or β‐hydroxyethyl groups, or a sulfhydryl group. The system could also reduce benzyl viologen but not methylene blue. Riboflavin did not replace proflavin for the photoproduction of hydrogen, This system may have potential for producing hydrogen with solar energy.
PHOTOREACTIVATION OF PYRIMIDINE DIMERS IN DNA FROM THYROID CELLS OF THE TELEOST, POECILIA FORMOSA
Authors: Achey P. M. , Woodhead A. D. , Setlow R. B.
Published: January 2008

Abstract— We have developed and used a simple technique to estimate the quantity of pyrimidine dimers in unlabeled cellular DNA. DNA is extracted from cells, treated with an endonuclease specific for dimers, and its molecular weight estimated by its electrophoretic mobility on alkaline agarose slab gels. The technique is used to show that cells from thyroid tissue of the fish Poecilia formosa have photoreactivating activity towards dimers in the cellular DNA.
RED LIGHT‐INDUCED REDUCTION OF A PARTICLE‐ASSOCIATED b‐TYPE CYTOCHROME FROM CORN IN THE PRESENCE OF METHYLENE BLUE*
Authors: Britz Steven J. , Schrott Erich , Widell Susanne , Briggs Winslow R.
Published: January 2008

Abstract— In the presence of methylene blue, red light causes the reduction of a h‐type cytochrome in particulate fractions from corn coleoptiles. Two types of difference spectra for the cytochromes in these fractions are presented: (a) red light‐minus‐dark in the presence of methylene blue, and (b) dithionite‐reduced‐minus‐oxidized. Comparison of these spectra shows that photoexcited methylene blue selectively reduces a b‐type cytochrome which constitutes at most only 30% of the total dithionite‐reducible cytochrome present in the most active fractions. The photoreducible cytochrome has an alpha band at room temperature near 557 nm. Bleaching of methylene blue precedes cytochrome reduction under appropriate conditions, suggesting that the photoreduced dye is donating an electron to the cytochrome. This electron transfer does not involve a flavin, at least as judged by the absence of light‐induced spectral changes attributable to flavins. Preliminary kinetic studies suggest that EDTA provides the pool of electrons for the reaction. The cytochrome cannot be assigned exclusively either to mitochondria or to endoplasmic reticulum, as judged by its sedimentation properties. These results and the current literature are discussed in the context of the hypothesis that this b‐type cytochrome may be involved in the photoreception mechanism for blue and uv light in vivo.
PHOTOCHEMISTRY OF HEPARIN‐ACRIDINE ORANGE COMPLEXES IN SOLUTION: PHOTOCHEMICAL CHANGES OCCURRING IN THE DYE AND POLYMER ON FLUORESCENCE FADING
Authors: Menter J. M. , Hurst R. E. , West S. S.
Published: January 2008

Abstract— Photolysis of acridine‐orange‐heparin complexes in N2‐ and O2‐saturated solution results in permanent photooxidation of AO with little or no concomitant change in the heparin moiety. The major photoproduct is mono‐N‐demethylated acridine orange; in O2‐saturated solution an additional minor oxygenated product, most likely the 10‐oxide (N‐oxide) or the 9‐acridanone (acridone) is also formed. The results suggest an intermolecular electron transfer between adjacently adsorbed dye molecules. The heparin moiety plays a significant role in the photochemistry by bringing dye molecules into favorable geometric orientation for biomolecular reaction and by means of specific dye‐polymer interactions.
DNA TURNOVER IN BUFFER‐HELD ESCHERICHIA COLI AND ITS EFFECT ON REPAIR OF UV DAMAGE
Authors: Tang Moon‐Shong , Wang Tzu‐chien V. , Patrick Michael H.
Published: January 2008

Abstract— Continuous DNA degradation and resynthesis, without a net change in cellular DNA content, were observed in buffer‐held, non‐irradiated E. coli B/r. This constant DNA turnover probably involves most of the genome and reflects random sites of DNA repair due to the polA‐dependent excision‐resynthesis repair pathway. Under these non‐growth conditions, it appears that at any given time there is a minimum of one repair site per 6.5 × 106 daltons DNA, each of which is at least 160 nucleotides long.

While the amount of DNA degradation is not influenced by prior exposure to UV radiation, the synthetic activity decreases with increasing UV fluence. We suggest that when sites of DNA turnover occur opposite to cyclobutyl dipyrimidines in UV‐irradiated cells, repair of the latter damage can be prevented. This implies that both beneficial and deleterious processes take place in irradiated buffer‐held cells, and that cell survival depends on the delicate balance between DNA turnover and repair of UV‐damage. Based on these findings, we propose a model to explain the limited repair observed during post‐irradiation liquid‐holding and to account for the large difference in cell survival between irradiation at low fluence rates (fluence‐rate dependent recovery) and at high fluence rates followed by liquid‐holding (liquid‐holding recovery).
NEW PHOTO‐CONVERTIBLE REACTIONS OF BLUE‐FLUORESCENT CALF α‐CRYSTALLIN
Authors: Fujimori Eiji
Published: January 2008

Abstract— Both native blue fluorescent α‐crystallin from calf lenses and UV (300 nm)‐irradiated blue‐fluorescent α‐crystallin, when further irradiated with 365 nm‐UV light, produce photo‐products capable of emitting a new fluorescence at 455 nm. Illumination of the photo‐products with 420 nm visible light regenerates the original fluorescence at 420–425 nm. In addition, another fluorescence at 400 nm has also been found in UV (300 nm)‐irradiated blue‐fluorescent α‐crystallin, when exposed to 365 nm‐UV light.
METHODS OF PREPARING CHLOROPHYLL a MULTILAYERS ON GLASS PLATES
Authors: Iriyama Keiji
Published: January 2008

Abstract— Preparative methods for forming chlorophyll a multilayers on glass plates were re‐investigated in relation to deposition ratios, and by checking the stability of chlorophyll u in the multilayers spectrophotometrically and by thin‐layer chromatography. The methods for measuring deposition ratios were also re‐examined and the best conditions selected.
STEPS IN THE POPULATION OF THE EMITTER IN THE BACTERIAL LUCIFERASE REACTION
Authors: Presswood Robert P. , Hastings J. Woodland
Published: January 2008

Abstract— The reaction of luciferase‐bound flavin hydroperoxide with both I‐1H and 1–2H decanal has been examined at 2°C in both low (0.01 M) and high (0.35 M) phosphate buffer, pH 7, where the kinetics and deuterium isotope effects are quite different. Upon reaction in both buffers there are rapid (<2 ms) increases in absorption at both 380 and W nm, followed by decay over the subsequent seconds and minutes. The changes at 380 nm exhibit a primary isotope effect and are rapid compared to bioluminescence, indicating that the scission of the aldehyde C — H bond occurs prior to the step responsible for populating the electronically excited state. However, the final absorbance change at 600 nm decays in parallel to bioluminescence under the several different conditions studied, suggesting the involvement of a long‐wavelength absorbing flavin species in the production of, the excited state. Evidence is also presented indicating that under certain conditions there may be two (sequential) steps, each of which exhibits a primary isotope effect involving the same H atom.
REMOVAL OF THYMINE‐CONTAINING PYRIMIDINE DIMERS FROM UV LIGHT‐IRRADIATED DNA BY S1 ENDONUCLEASE
Authors: Heflich Robert H. , Mahoney‐Leo Eileen , Maher Veronica M. , McCormick J. Justin
Published: January 2008

Abstract— S1 endonuclease was shown to remove thymine‐containing pyrimidine dimers from UV‐irradiated human DNA, although efficient removal could be demonstated only by using long digestion times, relatively high enzyme concentrations, and irradiation sufficient to yield dimer substitutions in DNA of 1 per 1W300 (dimers/base pair). Neutral and alkaline sucrose gradient analysis of strand break induction by S, of UV‐irradiated DNA suggests that recognition of the dimer by S, is the limiting factor in its removal and dimer removal usually results from attack on the dimer containing DNA strand without the induction of a double‐strand break.
KYNURENIC ACID — II. PHOTOSENSITIZING PROPERTIES
Authors: Pileni M. P. , Giraud M. , Santus R.
Published: January 2008

Abstract— The photosensitizing properties of kynurenic acid have been studied by 353 nm laser flash spectroscopy and steady state irradiations. Laser flash spectroscopy indicates that the kynurenic acid triplet is reduced by amino acids and nucleic acid bases. Photoreactions implying singlet oxygen formation are shown to occur. The photosensitized destruction of tryptophan which does not involve singlet oxygen is very efficient and shows specific features. Chemical and biological implications of this photo‐reactivity are discussed.
IN VIVO CHLOROPHYLL a FLUORESCENCE TRANSIENTS AND THE CIRCADIAN RHYTHM OF PHOTOSYNTHESIS IN GONYAULAX POLYEDRA
Authors: Sweeney Beatrice M. , Prkzelin Barbara B. , Wong Daniel , Govindjee
Published: January 2008

Abstract— The intensity of chlorophyll a fluorescence during the early part of fluorescence induction at O, initial fluorescence, and P, peak fluorescence, was higher during the day phase of the circadian cycle than during the night phase in continuous light (LL) conditions and was positively correlated with the rate of oxygen evolution. The circadian rhythm in fluorescence in LL persisted in the presence of 10μM 3–(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU), which blocks electron flow from photo‐system (PS) II in photosynthesis. The rhythmic changes in fluorescence intensity are consistent with a lower rate constant for radiationless transitions during the day phase than during the night phase of the circadian rhythmicity. The circadian changes in the intensity of fluorescence were abolished at 77K, which may indicate the importance of structural changes in membranes in circadian oscillations.