bluuebunny/crossref_metadata_2025 huggingface dataset:
THE WAVELENGTH DEPENDENCE OF HERPES SIMPLEX VIRUS INACTIVATION BY ULTRAVIOLET RADIATION
Authors: Detsch Richard M. , Bryant F. Dudley , Coohill Thomas P.
Published: January 2008

Abstract—

The effect of different wavelengths of ultraviolet (UV) radiation on Herpes simplex virus when assayed on mammalian cells (measured by plaque forming ability) was investigated. The wavelength dependence of viral inactivation was obtained for 11 different wavelengths over the region 238–297 nm. The resulting action spectrum does not closely follow the absorption spectrum of either nucleic acid or protein. The most effective wavelengths for viral inactivation are over the region 260–280 nm.
LOSS OF PHOTOREACTIVABILITY DURING LIQUID‐HOLDING IN ESCHERICHIA COL1 WP2
Authors: Roczen Diktmar , Mennigmann Horst‐Dieter
Published: January 2008

Abstract—

Loss of photoreactivability during liquid‐holding occurs much faster in Escherichia coli WP2 than has been reported for another strain of B/r (Harm, 1968). The underlying mechanism considerably reduces the maximum photoreactivation attainable within 30 min. The addition of caffeine to UV irradiated strain WP2 prevents the loss of photoreactivation activity. Similarly, a uvrA mutant also fails to show this loss of photoreactivation capacity. These results are consistent with the view that in WP2 the initial steps of excision repair take place during liquid‐holding and that they can preclude photoreactivation at a high rate. But it remains to be elucidated why different strains of B/r differ with respect to this rate.
SIMULATION ANALYSIS OF THE PHOTOCONVERSION PROCESS OF SQUID RHODOPSIN AT LIQUID HELIUM TEMPERATURE
Authors: Sarai Akinori , Kakitani Toshiaki , Shichida Yoshinori , Tokunaga Fumio , Yoshizawa Toru
Published: January 2008

Abstract—

The photoconversion process among squid rhodopsin, bathorhodopsin isorhodopsin and hypsorhodopsin was studied at liquid helium temperature. We evaluated the relative quantum yields of the photoconversion among four pigments by analysing the time‐dependent change of absorption spectra. The result suggests that hypsorhodopsin is the common intermediate of rhodopsin and isorhodopsin, and there is no direct conversion between rhodopsin and isorhodopsin. Furthermore, rhodopsin converts to hypsorhodopsin or bathorhodopsin much more efficiently than does isorhodopsin, and bathorhodopsin does not convert directly to hypsorhodopsin. It was also found that rhodopsin and isorhodopsin convert to bathorhodopsin more efficiently than to hypsorhodopsin. In particular, the quantum yield of conversion from rhodopsin to bathorhodopsin was found to be about twice as large as that from rhodopsin to hypsorhodopsin. This result is somewhat in disagreement with the result obtained from the laser flash experiments at room and liquid nitrogen temperatures. The reason for the difference between the two experimental results is discussed.
LIGHT‐INDUCED CAROTENE SYNTHESIS IN MUTANTS OF PHYCOMYCES WITH ABNORMAL PHOTOTROPISM
Authors: Jayaram M. , Leutwiler L. , Delbrück M.
Published: January 2008

Abstract—

Mutants of Phycomyces. abnormal in their phototropic responses (the mad mutants), have been tested for their responses in light‐induced carotene synthesis (LICS). The amount of carotene synthesized at any given fluence is significantly lower in the madA, madB and madD mutants than in the wild type. The amount of carotene is not lower in other mad mutants (madC, madE, madF and madG). The double mutant mad A madB and the triple mutant mad A madB madC show stronger effects. The wild type strain, as well as those carrying a single mad mutation (madA and madB) or those carrying two or three mad mutations (madA madB. madA madB madC) show closely similar sensitivity to LICS. This contrasts with phototropism and photoinitiation of sporangiophores which are sensitive to extremely small signals in the wild type and in which the madA mutation decreases the sensitivity by nearly a factor of 104 and madB mutation by a factor of 105. It appears that LICS does not share the signal amplification mechanisms characteristic of the other two responses.
NMR ANALYSES OF TRYPTOPHAN‐8‐METHOXYPSORALEN PHOTOREACTION PRODUCTS FORMED IN THE PRESENCE OF OXYGEN
Authors: Megaw J. , Lee‡ J. , Lerman S.
Published: January 2008

Abstract—

Proton‐made spectroscopy was performed on solutions of l‐tryptophan and 8‐mcthoxypsoralen (8‐MOP) in either D2O or DMSO‐d6 in the presence of oxygen before and after irradiation with 360 nm monochromatic light. Irradiation results in the loss of hydrogen atoms at the 3. 4 and 4′. 5′ positions of 8‐MOP and at the indole C2 position of tryptophan. Changes in the aliphatic regions of the spectra also occur with irradiation. It is postulated that generation of photoreaction products between 8‐MOP and tryptophan involves the 3.4 and 4′.5′ positions of 8‐MOP and the imidazole moiety of tryptophan.

Reprint requests to: Dr J. Megaw, Laboratory for Ophthalmic Research, Emory University School of Medicine, Atlanta. Georgia 30322. USA.
SPIN TRAPPING OF THE SUPEROXIDE RADICAL BY 4‐(N‐METHYLPYRIDINIUM) t‐BUTYL NITRONE
Authors: Sanderson Douglas G. , Chedekel Miles R.
Published: January 2008

Abstract—

The synthesis of 4‐(N‐methylpyridinium) t‐butyl nitrone (4‐MePyBN) and its use as a spin trap for superoxide radicals produced in aqueous solutions is reported (aN= 13.78 G, aHß= 1.65 G, and g = 2.0091). The half‐life of the spin adduct as a function of pH (83 s at pH 5.5, 78 s at pH 7.0, and 65 s at pH 8.0) the effects of iron salts, diethylenetriaminepentacetic acid (DETAPAC), and superoxide dismutase were examined, and comparisons made between 4‐MePyBN and 5,5‐dimethyl‐1‐pyrroline‐N‐oxide (DMPO) as spin trapping agents for the superoxide radical.
PHOTOCHEMICAL AND FREE RADICAL INITIATED REACTIONS OF 1,3‐DIMETHYLTHYMINE WITH ETHANOL
Authors: Shetlar Martin D.
Published: January 2008

Abstract—

The photochemically induced reaction of 1,3‐dimethylthymine (DMT) with ethanol gives four major alcohol adducts. These have been identified as l,3‐dimethyl‐6‐(1‐hydroxy‐1‐ethyl)thymine (1), 1,3‐dimethyl‐5‐(2‐hydroxy‐l‐pyl)uracil (2), and the cis and trans isomers of 5,6‐dihydro‐l,3‐di‐methyl‐6‐(l‐hydroxy‐l‐ethyl) thymine (3 and 4). The compounds 3 and 4 have been shown to be identical to the adducts produced in y‐ray irradiated ethanolic aqueous solutions of DMT. Cyclobutane dimers of DMT are also found in the photochemical reaction mixture. Reaction of 1‐hydroxyethyl radicals with DMT, initiated by decomposition of di‐t‐butyl peroxide, leads to formation of the same alcohol adducts, as well as to DMT adducts containing two molecules of ethanol. The acetone sensitized reaction of DMT with ethanol gives 1,3, and 4, along with a variety of adducts incorporating the acetone sensitizer.
PHOTOSENSITIZED INACTIVATION OF E. COLI CELLS IN TOLUIDINE BLUE‐LIGHT SYSTEM
Authors: Wakayama Yoshiko , Takagi Masamichi , Yano Keiji
Published: January 2008

Abstract—

E. coli cells were inactivated with visible light in the presence of toluidine blue as a photo‐sensitizer. This photodynamic effect was partially protected with α‐tocopherol. Not only pH but the concentration of the buffer during irradiation also affected the survival. The addition of osmotic stabilizers such as KCI, glycerol and polyethyleneglycol to the buffer increased the survival. The difference in singlet oxygen production in these reaction mixtures could not be related to these features. Furthermore, the survival was also dependent upon both irradiation temperature and cultivation temperature of the cells. These results with E. coli cells support the notion that one of the primary targets of toluidine blue sensitized photodynamic inactivation is cytoplasmic membrane, although other factors than cytoplasmic membrane also influence the survival of the cells.
ULTRAVIOLET INDUCED BINDING OF DAUNOMYCIN TO DNA
Authors: Gray P. J. , Phillips D. R.
Published: January 2008

Abstract—

Up to 10–15% of daunomycin present in solutions of DNA‐daunomycin remains irreversibly bound to DNA after 2 h of UV irradiation. Three times as much drug is irreversibly bound to DNA when oxygen is present, compared to deoxygenated solutions. Maximal amounts of the irreversibly bound drug are obtained between pH 5.5 and 7.5 and at an ionic strength of 0.76 M. Although the presence of daunomycin inhibits the extent of UV‐induced degradation of the DNA, the DNA is still extensively degraded and denatured in the time required for optimal yields of the DNA‐daunomycin photoproduct. This degradation of the DNA may impair its use as a lysosomotropic carrier of daunomycin.
DNA REPAIR IN V‐79 CELLS TREATED WITH COMBINATIONS OF PHYSICAL AND CHEMICAL CARCINOGENS*
Authors: Ahmed Farid E. , Setlow R. B.
Published: January 2008

Abstract—

Excision repair of DNA damage was measured by the photolysis of bromodeoxyuridine incorporated into parental DNA during repair in Chinese hamster V‐79 cells treated with 254 nm of ultraviolet radiation (UV), 7,12‐dimethylbenz[a]anthracene 5,6‐oxide (DMBA‐epoxide), N‐acetoxy‐2‐acetylaminofluorene (AAAF), 4‐nitroquinoline 1‐oxide (4NQO), 2‐methoxy‐6‐chloro‐9‐[3(ethyl‐2‐chloroethyl)‐aminopropylamino]acridine dihydrochloride (ICR‐170), X‐rays, ethylmethanesulfonate (EMS), methyl methanesulfonate (MMS) and combinations of these agents. Compared to normal human cells V‐79 were defective in repair of UV lesions and the lesions induced by the UV‐mimetic chemicals. The extent of the defects varied from 10 to 50% and was similar to those in Xeroderma pigmentosum group C cells (XP C). V‐79 cells repaired X‐ray damage and damage from the alkylating agents EMS and MMS to the same extent as human cells. Repair was additive after a combination of UV plus MMS indicating, as expected, that there are different rate‐limiting steps for removal of the damages from these agents. Repair was less than additive in cells treated with UV plus ICR‐170, AAAF plus ICR‐170, AAAF plus 4NQO, and 4NQO plus ICR‐170 and approximately equal to that observed for the higher of the two agents separately, indicating that there may be similar rate‐limiting steps for removal of lesions. Although the results on repair after combinations of UV plus 4NQO, UV plus DMBA‐epoxide or X‐rays plus MMS were difficult to interpret, there was not any inhibition of repair in these combinations.
ANALYSIS OF THE MECHANISM OF PHOTODYNAMIC INDUCTION OF SYNTHESIS OF A POLYPEPTIDE IN ARTHROBACTER SP.
Authors: Hoober J. Kenneth , Franzi Joseph
Published: January 2008

Abstract—

Synthesis of a 21000‐dalton polypeptide is greatly stimulated in a species of Arthrobacter by the combined influence of light, oxygen and a sensitizing dye. The dye must enter the cells for the effect to occur. The extent of photoinduction was not enhanced in the presence of D2O nor was it significantly inhibited by 10–20 mM azide or 1,4‐diazabicyclo [2.2.2]octane. The phenazine dye neutral red was nearly as effective as methylene blue and rose bengal in sensitizing photoinduction, although neutral red was inactive as a sensitizer of the photooxidation of histidine or methionine, singlet oxygen‐mediated reactions. Thus, generation of singlet oxygen does not seem to be a necessary step in the mechanism of induction. Neutral red had low activity as a sensitizer of the oxidation of sulfite, which proceeds by a radical mechanism. Considering also the known properties of phenazine compounds, the evidence supports the involvement of radical intermediates in the mechanism of photoinduction. Furthermore, the results suggest that the dyes must interact directly with an intracellular component, possibly DNA, for induction to occur.
CHARACTERIZATION OF THE RED LIGHT INDUCED REDUCTION OF A PARTICLE ASSOCIATED b‐TYPE CYTOCHROME FROM CORN IN THE PRESENCE OF METHYLENE BLUE*
Authors: Widell Susanne , Britz S. J. , Briggs W. R.
Published: January 2008

Abstract—

Methylene blue transfers electrons to a membrane‐associated b‐type cytochrome in particulate fractions from corn coleoptiles. The Km for methylene blue is less than 1 µM under optimal conditions. This reaction is destroyed by boiling, but not by 7 M urea. Kinetic analyses of the influence of light intensity on cytochrome reduction suggest that a first order photochemical reaction is limiting. Free EDTA may serve as an electron donor in this system at least at high methylene blue and protein concentrations. The photoactivity does not coincide either with mitochondrial or endoplasmic reticulum markers, and may be localized in plasma membrane. There is an estimated 5 times 10‐10 mol photoreducible cytochrome per g coleoptile tissue. Studies on the effect of pH on the reaction in the presence of methylene blue or thionine indicate that dye photoreduction itself is not rate‐limiting. Wavelength dependence studies suggest that it is methylene blue monomer and not dimer which mediates the reaction. Although oxygen is apparently required for the reaction, neither superoxide nor excited singlet oxygen appear to be involved. The reaction mechanism is still unknown.
PHOTOCHEMICAL REACTIONS OF THYMINE WITH CARBOXYLIC ACIDS. A MODEL FOR NUCLEIC ACID‐PROTEIN PHOTOCROSSLINKING
Authors: Toulme Francine , Hélène Claude
Published: January 2008

Abstract—

When nucleic acid bases are UV‐irradiated in the presence of carboxylic acids or carboxylate anions new photoproducts are formed as compared to the bases irradiated in the absence of carboxylic acids. The behavior of thymine and thymidine has been examined in detail. At least four photoproducts are formed in the presence of propionic acid and three in the presence of butyric acid. None of them appears to be a cyclobutyl dimer. From the concentration dependence of the rate of photoproduct formation it is concluded that the reactive excited species is the first excited singlet state of thymine. When 14C‐labelled thymine is irradiated in the presence of polyglutamic acid an important part of the radioactive material is covalently linked to the polymer. Photochemical reaction of thymine with glutamic (or aspartic) acid could thus induce crosslinks between proteins and nucleic acids. It is also shown that these photoproducts are stable under usual conditions of acidic hydrolysis of UV‐irradiated DNA.
PHOTOINITIATION OF ONE ELECTRON REACTIONS IN DIPEPTIDES AND PROTEINS CONTAINING TRYPTOPHAN AND TYROSINE
Authors: Sloper R. W. , Land E. J.
Published: January 2008

Abstract—

A radical transformation of the type Trṗ‐TyrOH → TrpH‐TyrȮ, previously observed by pulse radiolysis, has been detected following 265 nm laser excitation of oxygen saturated neutral aqueous solutions of TrpH‐TyrOH, TyrOH‐TrpH and cyclo‐TrpH‐TyrOH. A similar process was observed after photoexcitation of the proteins α‐lactalbumin and α‐chymotrypsin.
SENSITIZED TRIPLET FORMATION OF CHLOROPHYLL‐A AND ß‐CAROTENE
Authors: Jensen Niels‐Henrik , Wilbrandt Robert , Pagsberg Palle B.
Published: January 2008

Abstract—

The naphthalene‐sensitized formation of triplet excited chlorophyll‐a (Chl‐a) and all‐transß‐carotene has been studied by pulse radiolysis. The rate constants for transfer of triplet energy from naphthalene to Chl‐a and all‐transß‐carotene in benzene at 25°C are (3.6 ± 0.6)·109M‐1 s‐1 and (10.7 ± 1.2)·109M‐1 s‐1, respectively. The decays of the excited triplet states of naphthalene, Chl‐a and all‐transß‐carotene all follow a mixed first‐and second‐order mechanism. The first‐order rate constant for triplet decay is strongly dose dependent for naphthalene but only slightly dependent and independent of dose for Chl‐a and all‐transß‐carotene, respectively. The rate constants for triplet‐triplet annihilation are (1.4 ± 0.3)·109M‐1 s‐1 for Chl‐a and (3.6 ± 0.4)·109M‐1 s‐1 for all‐transß carotene. The nearly constant ratio k(ß‐carotene)/k(Chl‐a) for the bimolecular triplet energy transfer rate constants is discussed in terms of the molecular shapes of the two molecules. The energetics of the triplet‐triplet annihilation of all‐transß‐carotene are discussed, and it is proposed that production of the excited 1AB state may be a major route in the annihilation process.
THE PHOTOPHYSICS OF BONELLIN: A CHLORIN FOUND IN MARINE ANIMALS
Authors: Matthews J. Ioan , Braslavsky Silvia E. , Camilleri Patrick
Published: January 2008

Abstract—

The photophysical properties of bonellin, a free‐base chlorin, were studied in ethanolic solution. For the singlet excited state the following data were determined: an energy level, EBS= 187 ± 2kJ mol‐1, a lifetime, τf= 6.3± 0.1ns at 298 K, and fluorescence quantum yields, φr= 0.07 ± 0.02 (298 K) and 0.20 ± 0.04 (77 K). The S1→ T intersystem crossing quantum yield was φisc= 0.85 ± 0.1. No phosphorescence was observed at 298 K and 77 K. Based on quenching experiments the triplet state energy level was determined to be EBT= 180 ± 20 kJ mol‐1. A unimolecular decay rate constant, k1= (2.3 ± 0.5)· 103 s‐1 at room temperature, and a molar absorption coefficient, εT443= 9500 ± 500 M‐1 cm‐1, were obtained for the triplet state. This species was quenched by O2 with ko2= (1.7 ±0.3)· 108M‐1 s‐1, and by benzoquinone with kq= (5.2 ± 0.3)‐109M‐1 s‐1. The latter value, as well as the high value determined for the triplet annihilation rate constant, k2= (2 ± 0.5)· 109M‐1 s‐1, might reflect an electron transfer mechanism. Copper bonellin had a shorter triplet lifetime (>20 ns), which offers a possible explanation for its lack of photodynamic action.
PHOTOREVERSIBLE UV‐INACTIVATION OF MESSENGER RNA IN AN INSECT EMBRYO (SMITTIA SPEC., CHIRONOMIDAE, DIPTERA)
Authors: Jäckle Herbert , Kalthoff Klaus
Published: January 2008

Abstract—

Smittia embryos were UV‐irradiated during intravitelline cleavage. At this stage, nuclei are heavily shielded by yolk‐rich cytoplasm, and do not synthesize detectable amounts of RNA. Irradiation at 265, 285 and 295 nm wavelength caused biological inactivation, and pyrimidine dimer formation in maternal RNA as described earlier (Kalthoff, 1976; Jäckie and Kalthoff, 1978). In addition, we observed marked effects on protein synthesis: (1) The overall rate of [35S]‐methionine incorporation in vivo was reduced to less than half of the normal rate. (2) Two‐dimensional gel electrophoresis revealed quantitative variations in the synthetic rate of some polypeptides, and the appearance of new ones in UV‐irradiated embryos. (3) Translation of polyadenylated RNA from Smittia embryos in a cell‐free system was inhibited by UV irradiation in vivo. (4) The apparent degradation, during early embryogenesis, of maternal polyadenylated RNA was retarded in UV‐irradiated embryos.

Exposure to light (400 nm) after UV caused partial photoreversal of all UV effects observed. Both the photoreactivable sector of UV‐inactivation, and the photoreactivated portion of UV inhibition of protein synthesis, were correlated with the amounts of pyrimidine dimers generated in maternal RNA by UV irradiation at the three wavelengths used. These correlated effects were produced most efficiently by 295 nm radiation, indicating the involvement of photosensitizing components in the embryos. Our data show, for the first time to our knowledge, that animal mRNA, after UV irradiation, can be photoreactivated in vivo. Moreover, our results strongly suggest that the photorepairable lesions consist of pyrimidine dimers generated in a photosensitized reaction.
THE EXPRESSION OF LIQUID HOLDING RECOVERY IN ULTRAVIOLET‐IRRADIATED ESCHERICHIA COLI REQUIRES A DEFICIENCY IN GROWTH MEDIUM‐DEPENDENT DNA REPAIR
Authors: Tang Moon‐Shong , Smith Kendric C.
Published: January 2008

Abstract—

Ultraviolet (UV) irradiated Escherichia coli K‐12 recA cells (but not rec+ cells) show enhanced survival if they are held in buffer prior to plating for viability. To understand the role of the recA mutation in this liquid holding recovery (LHR) phenomenon, we have studied LHR in a temperature sensitive recA 200 mutant. The detection of LHR requires that the irradiated cells be recA when they are plated on growth medium, but the recA deficiency plays no role during liquid holding (LH). We conclude that it is the extreme sensitivity of recA cells in growth medium to unrepaired DNA daughter‐strand gaps that magnifies the beneficial effects of the excision repair of DNA lesions during LH. Furthermore, we demonstrate a correlation between a strain's inability to perform growth medium dependent repair and its ability to express LHR. The relative amount of LHR was: recA > recF > lexA > recB > wild type (with the recB and wild‐type strains showing negative LHR). Two strains did not show this correlation; the uvrD strain showed less LHR than expected from its UV radiation sensitivity, while the polA strain showed more. The molecular bases for these exceptions are explored.
CONTROL BY PHYTOCHROME OF CHLOROPHYLL SYNTHESIS IN SEEDLINGS OF SORGHUM VULGARE
Authors: Sawhney S. , Oelze‐Karow H. , Sawhney N. , Mohr H.
Published: January 2008

Abstract—

The strong effect of light pretreatments on the synthesis of chlorophyll‐a and‐b in the shoot of Sorghum vulgare (kept under saturating white light) can be attributed to phytochrome only. No specific blue light effect was found. The phytochrome system appears to function perfectly normally under these conditions. Escape from reversibility is not detectable up to approximately 40 min after the onset of an inductive red light pulse. Thereafter, escape is fast, being completed at approximately 2.5 h after the inductive light pulse.
FLUORESCENCE OF THE COENZYME ANALOG NICOTINAMIDE FORMYCIN DINUCLEOTIDE
Authors: Gabriel Jerome L. , Plaut Gerhard W. E.
Published: January 2008

Abstract— Emission spectra of unbound reduced nicotinamide formycin dinucleotide (NFDH) revealed the presence of two major conformations of the coenzyme in solution: when examined at excitation wavelengths at or below 307 nm, emission spectra contained peaks at 343 and 447 nm; when excited above 307 nm, an additional maximum appeared at 355 nm and the peak of the dihydronicotinamide emission band shifted from 447 to 440 nm. Both conformers are probably detected at the longer wavelengths since the emission peak at 343 nm was retained. Identical changes occurred in the emission spectra of NFD+, however, the dihydronicotinamide emission between 440 and 447 nm was absent. Several mechanisms which may account for the presence of these conformers have been considered. The choice has been narrowed to conformations with ring‐ring interactions of the formycin and nicotinamide moieties resulting from (a) formycin tautomerization or (b) heterogeneity of glycosidic bond angles in the structures. The efficiency of intramolecular energy transfer from the formycin to the dihydronicotinamide moiety for free NFDH in aqueous solution was 84% and declined slightly (to 77%) when measured in 1,2‐propanediol. NFD+ has coenzyme activity for NAD‐specific isocitrate dehydrogenase (Plaut et al., 1979). The emission spectrum of enzyme bound NFDH was altered markedly in the presence of manganese isocitrate; emission intensity at 343 and 355 nm decreased while the emission from the dihydronicotinamide ring at 433 nm increased, when NFDH was excited at 310 nm. This shift in emission intensity was indicative of an increase in energy transfer within the NFDH molecule, caused by a change in coenzyme conformation upon binding to the enzyme‐substrate complex.
THE FLUORESCENCE DECAY OF REDUCED NICOTINAMIDES IN AQUEOUS SOLUTION AFTER EXCITATION WITH A UV‐MODE LOCKED Ar ION LASER
Authors: Visser A. J. W. G. , Hoek A. van
Published: January 2008

Abstract— The fluorescence decay kinetics of the reduced nicotinamides NMNH, NADH and NADPH in aqueous solution were investigated using an Ar ion laser, mode locked in the UV, as source of excitation and single photon counting electronics in the detection system allowing for a time resolution in the picosecond range. Analysis of the experimental fluorescence decay showed that the dinucleotides did not follow a single exponential decay law. Good fitting was accomplished with a sum of two exponentials. The mononucleotide fluorescence decay was a single exponential for at least 95% of its amplitude.

The heterogeneity in lifetimes of the fluorescence of the dinucleotides was interpreted in terms of an exciplex mechanism.
INCORPORATION OF 11,12‐DIHYDRORETINAL INTO THE RETINAE OF VITAMIN A DEPRIVED RATS
Authors: Crouch Rosalie , Katz Sidney , Nakanishi Koji , Gawinowicz M. A. , Balogh‐Nair Valeria
Published: January 2008

Abstract— The incorporation of 11,12‐[15–3H]‐dihydroretinal, a retinal in which the crucial 11‐ene is saturated, into the retinae of vitamin A deficient rats as a result of intraperitoneal injection of the corresponding alcohol was shown by the presence of the tritium label in the rod outer segments and by identification of the extracted retinals using high pressure liquid chromatography. The amplitude of the electroretinogram (ERG) b‐wave, diminished as the result of vitamin A deprivation, was not affected by administration of the analogue, although similar treatment of deprived litter mates with trans retinal restored the ERG b‐wave amplitude to a normal level.

The evidence that the analogue is bound to opsin forming 11,12‐dihydrorhodopsin is as follows: (1) when incubated with 11‐cis retinal, extracts from vitamin A deficient rats regenerate 1.4 nmol rhodopsin while extracts from rats deficient in vitamin A and supplemented with 11,12‐dihydroretinal regenerate 0.6 nmol rhodopsin indicating binding of the dihydroretinal blocks rhodopsin regeneration. (2) 11,12‐dihydroretinal is shown to remain unchanged in hexane‐washed retinae after extraction with methylene chloride and (3) injection of retinal into animals previously injected with 11,12‐dihydroretinal also fails to restore visual sensitivity as measured by the ERG b‐wave. Our results indicate that the dihydro‐chromophore occupies the same binding site as the natural 11‐cis retinal and that occupation of the chromophore binding site of opsin is not sufficient to restore the visual sensitivity in a vitamin‐A‐deprived animal.
THE EMBRYOTOXIC EFFECT OF PHOTOTHERAPY: SEPARATION OF THERAPEUTIC AND GAMETOTOXIC ACTIVITIES
Authors: Speck, William T. , Rosenkranz, Pnina G. , Behrman Michael , Rosenkranz† Herbert S.
Published: January 2008

Abstract— Illumination of gametes of the American sea urchin with visible light from a phototherapy unit causes abnormal development. Filters prevent these embryotoxic effects and permit their separation from the therapeutic effect of these lights, i.e. conversion of bilirubin to water‐soluble products.
Book Reviews
Authors: Zuclich Joseph A. , Harrison Joseph M. , Duráan Nelson
Published: January 2008

Book reviewed in this article:

The Effects of Constant Light on Visual Processes. Edited by T. P. Williams and B. N. Baker. Plenum Press, New York, 1980. 455 pp. $45.00.

Radiation Biology and Chemistry: Research Developments. Edited by H. E. Edwards, S. Navaratnam, B. J. Parsons and G. O. Phillips. Elsevier Scientific, Amsterdam, 1979. 505 pp. $78.00
THE WAVELENGTH DEPENDENCE OF ULTRAVIOLET LIGHT—INDUCED CELL KILLING AND MUTAGENESIS IN L5178Y MOUSE LYMPHOMA CELLS
Authors: Jacobson Elizabeth D. , Krell Kenneth , Dempsey Mary J.
Published: January 2008

Abstract The wavelength dependence of ultraviolet radiation‐induced cell killing and mutagenicity in L5178Y mouse lymphoma cells has been determined from 235 nm to 313 nm. Cells were irradiated in phosphate buffered saline at 20°C. The amount of cell killing was determined by cloning in soft agar medium immediately after irradiation. Mutation frequency was determined, after a 3‐day expression time, by cloning in soft agar medium in the presence and the absence of 5‐bromo‐2′‐deoxyuridine (BrdUrd). The endpoint used to quantitate lethal effects was the exposure necessary to reduce the surviving fraction to 10%, while the endpoint for mutagenesis was the exposure necessary to increase the frequency of BrdUrd‐resistant colonies ten‐fold over the background level. Data were corrected for quantum energy and the action spectra for cell killing and mutagenesis were plotted as relative biological effectiveness per quantum vs wavelength, relative to the effect at 265.2 nm. Both action spectra show broad maxima at 270 nm, and are very similar to the action spectra determined by Rothman and Setlow (1979) for pyrimidine dimer formation and cell killing in V‐79 cells.
INACTIVATION OF NORMAL AND MUTANT NEUROSPORA CRASSA CONIDIA BY VISIBLE LIGHT AND NEAR‐UV: ROLE OF 1O2, CAROTENOID COMPOSITION AND SENSITIZER LOCATION
Authors: Thomas Sharon A. , Sargent M. L. , Tuveson R. W.
Published: January 2008

Abstract— Inactivation of Neurospora crassa conidia from wild‐type and mutant strains by visible and near‐UV light has been investigated in the presence and absence of photosensitizing dyes. Inactivation by near‐UV is virtually unchanged by the presence of deuterium oxide or azide suggesting that, contrary to the situation with visible light and photosensitizing dyes, 1O2 is not involved in any substantial way in the formation of lethal lesions. The finding that carotenoid deficient strains are similar to wild‐type strains in sensitivity to near‐UV inactivation is consistent with 1O2 not being involved.

Photodynamic inactivation of conidia by visible light occurs in the presence of methylene blue (MB), toluidine blue O (TB), or acridine orange (AO). Carotenoid deficient strains are more sensitive to such inactivation only when MB and TB are used. These results support the contention that MB and TB mediated damage involves the cell membrane where carotenoids are available for quenching, whereas AO mediated damage occurs in the nucleus sequestered from the protective influence of carotenoids.

A newly isolated, lemon–yellow mutant, mapping to the al‐1 locus, exhibits sensitivities to photodynamic inactivation similar to other pure‐white mutants at the same locus. The sensitivity of this pigmented mutant is apparently related to insufficient unsaturation (seven to nine double bonds) of the two colored carotenoids, zeta–carotene and neurosporene, produced by the mutant.
WAVELENGTH DEPENDENCE OF QUANTUM YIELDS AND PRODUCT DISTRIBUTION IN THE ANAEROBIC PHOTOCHEMISTRY OF BILIRUBIN DIMETHYL ESTER
Authors: Holzwarth A. R. , Schaffner K.
Published: January 2008

Abstract— (Z,Z)‐Bilirubin dimethyl ester exists in two or more forms in solution, and photorearranges to the (E,Z)‐ and (Z,E)‐isomers. Deaerated solutions of bilirubin dimethyl ester in 2‐methyltetrahydrofuran and chloroform/ethanol were irradiated with light of 10nm bandwidth in the range 380–470 nm at room temperature. Absorption difference spectroscopy showed that the solution forms of bilirubin dimethyl ester differ in their photoreactivity, and that the quantum yields of their disappearance and the distribution of the photorearrangement isomers are wavelength dependent.
GROWTH DELAY INDUCED IN ESCHERICHIA COLI BY NEAR‐ULTRAVIOLET RADIATION: RELATIONSHIP TO MEMBRANE TRANSPORT FUNCTIONS*
Authors: Kubitschek H. E. , Doyle R. J.
Published: January 2008

Abstract— Rates of leucíne transport, oxygen utilization, and glucose and succinate uptake were determined in cultures of Escherichia coli B/r before and after exposure to near‐UV light. Within experimental errors, rates of uptake of glucose and of succinate were proportional to growth rate at all times during the recovery or growth delay period following near‐UV exposure and the same proportionality was maintained in unexposed cultures. However, rates of leucine uptake and incorporation and of oxygen utilization were not related to growth rate in a simple fashion. The results suggest that inhibition of carbon source transport is a fundamental component, and may be a primary mechanism, in growth delay induced by near‐UV radiation.
ON THE SPATIAL CORRELATION BETWEEN THE PROTEIN SURFACE AND THE ELECTRON TRANSFER CYCLE IN BACTERIAL PHOTOSYNTHETIC REACTION CENTERS
Authors: Giangrande M. , Kevan Larry
Published: January 2008

Abstract— n‐Doxylstearic acids are shown to be electron acceptors in reaction centers from R. spheroides R‐26 mutant illuminated with 860 nm light. The electron accepting efficiency varies with n, thus with the location of the nitroxide moiety on the stearic acid chain, and is maximum for 12‐doxylstearic acid. In this molecule the nitroxide moiety is 1.4 nm from the polar carboxyl carbon based on molecular models. If the nitroxide moiety is located in or near the polar reaction center protein surface, the results suggest that the quinone‐iron complex, which is the ultimate electron acceptor from a bacterio‐chlorophyll dimer in the reaction center, is located ∼ 1.4 nm from the protein surface. The protein itself is estimated to have a diameter of 5.4 nm assuming spherical symmetry, so it is postulated that the quinone‐iron complex is located on one side of the protein.
THE SPATIAL DISTRIBUTION OF LIGHT EMISSION FROM LIQUID PHASE BIO‐ AND CHEMILUMINESCENCE: VARIATIONS WITH CONTAINER TYPES, TURBIDITY AND CONTAINER FROSTING
Authors: Rich Edwin S. , Groover Clark H. , Wampler John E.
Published: January 2008

Abstract— The spatial distribution of emitted light from liquid phase bioluminescence and chemiluminescent sources in three common types of containers has been evaluated. These sources, while theoretically isotropic, exhibit considerable anisotropy due to reflection and refraction effects at the interfaces between the solution, the container and the surrounding air. This anisotropy represents a considerable systematic error (>25%) in some values of quantum yields reported in the literature. The degree of asymmetry in spatial distribution depends on the solution volume, the refractive index, and the degree of light scattering in the solution. Quantitative evaluation of the projected image of these sources using a video camera system indicates that a major contribution to this asymmetry is due to reflection at the meniscus. Since container frosting removes the variability due to scattering, volume changes, refractive index differences and even, to some extent, use of different types of containers, it is recommended that quantum yields and comparative measurements be determined using frosted containers and point source geometry. The container of choice is a frosted, 1 ± 7.5 cm test tube.
PHOTOREACTIVATION OF UV‐B DAMAGE IN BACTERIOPHAGE φX174 DNA†
Authors: Patrick J. R. , Brabham D. E. , Achey P. M.
Published: January 2008

Abstract— The fraction of biological damage in isolated single‐strand and double‐strand forms of bac‐teriophage DNA resulting from pyrimidine dimers following exposure to germicidal UV (254 nm) and UV‐B (280‐320. nm) radiation has been compared. Radiation from a Westinghouse FS‐40 sunlamp filtered through a cellulose acetate sheet was used as the UV‐B radiation source. Biological damage from pyrimidine dimers was determined by measuring the survival of the viral DNA with and without photoreactivation, an enzymatic process specific for repair of pyrimidine dimers. The same fraction of biological damage in the single strand and double–strand forms of φX174 DNA is repairable by photo‐reactivation following exposures to germicidal UV and UV‐B radiation.
PROTON TRANSFER IN THE PRIMARY PROCESS OF VISION
Authors: Sarai Akinori , Kakitani Toshiaki , Kakitani Hiroko
Published: January 2008

Abstract— Proton transfer was theoretically examined as a possible primary process of vision. The motion of protons in the adiabatic potential of the Schiff base hydrogen bond was investigated in terms of quantum mechanics. The probability of proton transfer from the Schiff base nitrogen (i.e. the unprotonation of Schiff base) was found to increase as the retinal rotated around 11–12. double bond by 90°. The results also suggested that the proton transfer can take place before or during the transition from the excited to ground state (excited state proton transfer). We proposed that such excited state proton transfer is one of the elementary processes in primary visual photochemistry, and this process leads to the unprotonated visual pigment, hyposorhodopsin, which has been experimentally verified as one of the primary photoproducts of rhodopsin. The probability of this process could be comparable to the conventional process leading to the protonated intermediate, bathorhodopsin. The relation of these results with the recent experimental data is discussed.
PHOTOINHIBITION OF STIMULABLE BIOLUMINESCENCE IN MARINE DINOFLAGELLATES
Authors: Hamman J. P. , Biggley W. H. , Seliger H. H.
Published: January 2008

Abstract— Different genera of bioluminescent photosynthetic dinoflagellates exhibit different mechanisms for the inhibition of stimulable bioluminescence during daylight. These are (a) reduction in bioluminescence capacity, (b) increased refractoriness to mechanical stimulation, and (c) inhibition of transmission of signals from mechanical receptor sites to bioluminescence emission sites. The increase in stimulable bioluminescence that in nature mirrors the decrease in sunlight intensity prior to sunset is dependent upon the logarithm of the ambient irradiation intensity. Photoinhibition of bioluminescence in all species examined except Gonyaulax polyedra is the result of absorption of light in the blue region of the spectrum.
CIRCULAR DICHROISM OF THE PHYTOCHROME CHROMOPHORES IN NATIVE AND DENATURED STATE
Authors: Brandlmeier Thomas , Lehner Harald , Rüdiger Wolfhart
Published: January 2008

Abstract— The circular dichroism spectra of oat phytochrome were recorded. Qualitatively, the same spectra were found for large (360 kilodaltons) and small (60 kilodaltons) phytochrome. Quantitative CD data were reported for small Pr and Pfr (photoequilibrium mixture with 20% Pr) in tris buffer (native state) and in acid urea (denatured state). Further, the CD spectra of a phytochromobilinpeptide in acid solution with and without urea were recorded. Differences between the data in native and denatured state are discussed.
PHOTODIMERIZATION OF 1,3‐DIMETHYL‐5‐CHLOROURACIL*
Authors: Morrison Harry , Izuno Christine , Byrn Stephen , McKenzie Ann
Published: January 2008

Abstract— 1,3‐Dimethyl‐5‐chlorouracil dimerizes upon direct photolysis in aqueous solution to give one major photodimer. X‐Ray analysis has been used to identify the dimer as the anti head‐to‐tail isomer, IV.
PHOTOINACTIVATION OF ANTHRACYCLINES*
Authors: Williams Bruce A. , Tritton Thomas R.
Published: January 2008

Abstract— When adriamycin or daunomycin is irradiated at 366 nm, the drug loses its cytotoxic activity against Sarcoma 180 cells in culture. The half‐time for inactivation is about 9 h. Laboratory fluorescent lights also inactivate these anthracyclines with a half‐time of about one day. The photoinactivated drugs do not interact effectively with the anthracycline transport system and consequently are not taken up into the cell. Fluorescence and NMR spectroscopy yield spectra identical to native drug but with reduced peak intensities. Likewise, high pressure liquid chromatographic analysis does not reveal any new chemical species in photolyzed anthracyline solutions. Gel filtration chromatography, however, shows that the photoinactivation process is accompanied by the formation of drug polymers which are suggested to be the inactive species.
ULTRAVIOLET RADIATION‐INDUCED TUMORS DO NOT ARISE FROM A SUBPOPULATION OF ULTRAVIOLET‐RESISTANT CELLS*
Authors: Fisher Michael S.
Published: January 2008

Abstract— This study was designed to determine whether UV‐induced tumors have a selective growth advantage in the autochthonous host by virtue of possessing a heritable resistance to UV‐induced lethality. Several fibrosarcomas were induced either by repeated exposure of C3H mice to UV radiation from FS40 sunlamps or by subcutaneous injection of C3H mice with a chemical carcinogen (methylcholanthrene). Tissue culture lines of these tumors were tested in vitro for susceptibility to the lethal effects of UV radiation from an FS40 sunlamp. Lethality was assessed by measuring colony formation as a function of increasing dose of radiation. Cells from the UV‐induced fibrosarcomas were not more resistant to the lethal effects of UV radiation than cells from methylcholanthrene‐induced fibrosarcomas or cells from a nontumorigenic C3H fibroblast cell line. This suggests that UV‐induced tumors do not arise from a subpopulation of UV‐resistant cells.
SPIN‐TRAPPING AND ESR STUDIES OF THE DIRECT PHOTOLYSIS OF AROMATIC AMINO ACIDS, DIPEPTIDES, TRIPEPTIDES AND POLYPEPTIDES IN AQUEOUS SOLUTIONS—I. PHENYLALANINE AND RELATED COMPOUNDS
Authors: Lion Yves , Kuwabara Mikinori , Riesz Peter
Published: January 2008

Abstract— The direct UV photolysis of l‐Phe and peptides containing l‐Phe in aqueous solutions has been investigated at room temperature. The short‐lived free radicals formed during photolysis were spin‐trapped by t‐nitrosobutane and identified by electron spin resonance. During the photolysis of l‐Phe the decarboxylation and the deamination radicals were spin‐trapped. For N‐formyl and N‐acetyl‐l‐Phe the decarboxylation radicals were observed. For dipeptides containing Phe the decarboxylation radicals were observed and in some cases the deamination radicals from the N‐terminal residue were found. For the tripeptides Gly‐l‐Phe‐l‐Ala and Gly‐Gly‐l‐Phe, the C‐terminal decarboxylation radical was spin trapped; for l‐Phe‐Gly‐Gly only the deamination radical of the N‐terminal residue could be detected. However, for Gly‐l‐Phe‐Gly, five different radicals were identified. The results of the spin‐trapping experiments of the 260 nm photolysis of RNase‐S‐peptide, containing 20 amino acid residues, was interpreted in terms of a chain scission between the alpha carbon of the Phe residue and the adjacent carbonyl group.
SKIN DAMAGE IN ADULT AMPHIBIANS AFTER CHRONIC EXPOSURE TO ULTRAVIOLET RADIATION
Authors: Zavanella Teresa , Losa Massimo
Published: January 2008

Abstract— The effects of repeated UV exposure on the skin of the European crested newt, Triturus cristatus carnifex, have been investigated. The animals were irradiated 3 times per week with a Westing‐house FS40T12 fluorescent sun lamp (wavelength spectrum 275–350 nm). Two groups of animals received the same total fluence of 1.3 × 105 J/m2 in single fluences of either 1570 J/m2 (group A) or 9430 J/m2 (group C), and one group received a total fluence of 2.6 × 105 J/m2 in single fluences of 4710 J/m2 (group B). All the animals were killed 7 months after the first UV exposure, but at different intervals after the last exposure. Striking epidermal hyperplasia was found in the newts irradiated at the lower fluence rate (group A). In the animals given the higher total fluence (group B), the most prominent skin changes were dermal fibrosis and irregular thinning and thickening of the epidermis. No significant skin changes were found in group C., in which if there had been UV lesions, they had been repaired during the 5 month interval between the last irradiation and the killing of the animals. No skin tumors developed in any experimental group.
PICOSECOND TRANSIENT BEHAVIOR OF REACTION‐CENTER PARTICLES OF PHOTOSYSTEM I ISOLATED FROM SPINACH CHLOROPLASTS. ENERGY AND ELECTRON TRANSFER UPON SINGLE AND MULTIPLE PHOTON EXCITATION
Authors: Kamogawa Keiji , Namiki Akira , Nakashima Nobuaki , Yoshihara Keitaro , Ikegami Isamu
Published: January 2008

Abstract— Primary processes of photosynthesis in the picosecond timescale were investigated with highly enriched reaction center particles of photosystem I (PS I) prepared from spinach chloroplasts. Spectral changes were observable even under conditions of single photon excitation for each reaction center. Immediately after excitation, bleaching was observed at 676 nm, the absorption peak of the antenna chlorophylls. Several effects were observed which depended upon the number of photons absorbed by a reaction center. Upon multiple photon excitation the intensity of bleaching decayed quickly. Single photon excitation resulted in no obvious decay of the main bleaching band, but produced a remarkable variation of the band feature. The most characteristic change was the appearance of a band around 700 nm which had not decayed even after 8 ns. In an oxidized sample, P700+, the main bleaching decayed without any spectral change. These observations indicate that the excitation transferred from antenna chlorophylls to P700. Subsequently P700 was oxidized resulting in the long‐lived P700+. The overall process apparently proceeds with t1/e∼ 25 ps upon single photon excitation.
ROLES OF THE RELA+ GENE AND OF 4‐THIOURIDINE IN NEAR‐ULTRAVIOLET (334 nm) RADIATION INHIBITION OF INDUCED SYNTHESIS OF TRYPTOPHANASE IN ESCHERICHIA COLI B/r
Authors: Sharma R. C. , Wingo R. J. , Jagger J.
Published: January 2008

Abstract— Near‐ultraviolet radiation (near UV; 300–380 nm) is known to inhibit the induced synthesis of tryptophanase by tryptophan in Escherichia coli, showing an action spectrum similar to that for near‐UV‐induced growth delay. The present work shows that a relA mutant of E. coli B/r exhibits 50% as much monochromatic near‐UV (334 nm) inhibition of tryptophanase induction as the wild type, and that a mutant lacking 4‐thiouridine, an unusual nucleoside in tRNA, exhibits < 10% as much inhibition of tryptophanase induction. These findings indicate that 4‐thiouridine is almost the sole chromophore for this effect in E. coli B/r, but that only 50% of the effect operates by a mechanism utilizing the relA+ gene product; growth delay appears not to be primarily involved.
PHOTOBINDING OF PSORALEN AND 8‐METHOXYPSORALEN TO CALF THYMUS DNA
Authors: Sherman Warren V. , Grossweiner Leonard I.
Published: January 2008

Abstract— The photobinding of psoralen and 8‐methoxypsoralen to calf thymus DNA induced by 365 nm radiation has been measured for different concentrations of the furocoumarin and nucleotides. The results are consistent with the assumption that dark complexing of the furocoumarin to DNA is a pre‐condition for photobinding, but do not exclude the possibility that the free furocoumarin participates in the reactions. The analysis with ‘large target’ diffusion theory indicates that photobinding should be inefficient for the free excited singlet state and competitive with reactions of the dark‐complexed sensitizer for the free triplet state. The analysis indicates also that the diffusive reactions of singlet oxygen generated by the free furocoumarin can compete with photoadduct formation.
DECREASED HOST CELL REACTIVATION OF UV‐IRRADIATED ADENOVIRUS 5 BY FIBROBLASTS FROM COCKAYNE'S SYNDROME PATIENTS
Authors: Day Rufus S. , Ziolkowski Chuck H. J. , DiMattina Michael
Published: January 2008

Abstract— Over a period of 5 years, we performed 29 experiments in which survival curves of UV‐irradiated adenovirus were determined using fibroblast strains from 10 normal persons and from 7 persons having Cockayne's syndrome. In all of these, the survival of UV‐irradiated adenovirus 5 was less when assayed using monolayers of fibroblasts from Cockayne's syndrome patients than from normal persons. Survival curves using normal fibroblasts were, within error, straight lines on a log survival vs. linear fluence plot. Survival curves obtained using Cockayne's syndrome fibroblasts showed 2 components: an initial sensitive component, reflecting the behavior of approx. 75% of the infected cells, followed by a component having normal sensitivity. In the 28 experiments that were considered reliable, 58 curves were done using Cockayne's fibroblasts, 41 using normal human fibroblasts. Although experimental variation was encountered, there was no individual case in which sensitivity as measured using Cockayne's was equal to (or less than) the sensitivity measured using normal fibroblasts.
PHOTOINDUCED REACTION OF DIMETHYLNITROSAMINE WITH DNA AND POLYNUCLEOTIDES
Authors: Arfellini G. , Prodi G. , Rocchi P. , Grilli S.
Published: January 2008

Abstract— The interaction between products from dimethylnitrosamine photolytic breakdown and DNA is time‐dependent and the reaction with polyguanylic acid is 36 times higher than that occurring with other polyribonucleotides; such interactions occur only if nucleic acids are present during dimethylnitrosamine photolytic breakdown. Among interaction compounds, neither O6‐methyl‐ nor 7‐methylguanine are observable; on the contrary, N‐methylhydrazine and trimethylamine are always found in acid and alkaline hydrolysates of DNA and polynucleotides. These findings are very similar to the results previously found in biological in vivo and in vitro systems and suggest a possible usefulness of this physicochemical system as an analogical model of chemical carcinogenesis.