bluuebunny/crossref_metadata_2025 huggingface dataset:
INHIBITION OF Herpes virus PLAQUING CAPACITY IN HUMAN DIPLOID FIBROBLASTS TREATED WITH GILVOCARCIN V PLUS NEAR UV RADIATION
Authors: Bockstahler L. E. , Elespuru R. K. , Hitchins V. M. , Carney P. G. , Olvey K. M. , Lytle C. D.
Published: January 2008

Abstract— The capacity of human fibroblasts to support plaque formation by Herpes simplex virus following treatment of the cells with gilvocarcin V, a polyaromatic C‐glycoside. plus near ultraviolet radiation (UVA,320–400 nm) was examined. Gilvocarcin V, plus UVA radiation, effectively inhibited host cell capacity at concentrations five orders of magnitude lower than that of 8‐methyoxypsoralen required for capacity inhibition at similar levels of UVA radiation. This result extends the observation of unusual biological potency of UVA‐activafed gilvocarcins from bacterial cells to human cells.
PHYTOCHROME‐ and BLUE PIGMENT‐MEDIATED LEAF MOVEMENTS: EXPERIMENTAL APPROACH IN THE SIGNAL TRANSDUCTION
Authors: Roblin G. , Fleurat‐Lessard P. , Everat‐Bourbouloux A. , Bonmort J. , Moyen C.
Published: January 2008

Abstract— Leaflet movements of Cassia fasciculata are induced by transferring leaves from light to darkness or from darkness to light. Phytochrome mediates the dark‐induced closure whereas a blue and far red light absorbing pigment (cryptochrome?) is the photoreceptor triggering the light‐induced opening. These movements are the result of reversible turgor variation driven by ionic migrations (H+, K+, Cl−) in cortical parenchyma cells of motor organs (“pulvini”) localized at the leaflet base. Calcium plays a predominant role in the regulation of the movements as shown by the inhibitory effects of chelators (EDTA, EGTA), intracellular antagonist TMB‐8 and by the promoting effect of ionophore A 23187. Compounds known as calcium channel blockers (LaCl3, verapamil and nifedipine) inhibited whereas Bay K 8644, a calcium channel activator, promoted the phytochrome‐mediated movement. In contrast, all these calcium channel modulators had no effect on the blue pigment‐mediated movement. From these results, it is suggested that calcium is not mobilized in the same manner in the two types of movements: possibly from external stores in the phytochrome‐mediated response and from internal stores in the blue pigment‐mediated response. Calcium acts possibly through calmodulin as suggested by a modification in the kinetics of the movements induced by inhibitors of calmodulin action (trifluoperazine, R 24571, W‐7). The unexpected promotion of the movements by these inhibitors shows that calmodulin action on the ion migrations is not simple and direct. Experimental observations suggested that regulation might be done through cAMP metabolism. db‐cAMP promoted the movements. Compounds known either to activate adenylate cyclase (prostaglandins, forskolin) or to inhibit phosphodiesterase (imidazolidinones, ICI 58301) induced the same modifications as db‐cAMP. By contrast, a phosphodiesterase activator (imidazole) inhibited the movements.
LIGAND‐DEPENDENT INTERACTION OF RUTHENIUM(II) POLYPYRIDYL COMPLEXES WITH DNA PROBED BY EMISSION SPECTROSCOPY
Authors: Mesmaeker Andree Kirsch‐De , Orellana Guillermo , Barton Jacqueline K. , Turro Nicholas J.
Published: January 2008

Abstract— The nature of the interaction in buffered aqueous solution of several homo and heteroleptic ruthenium(II) polypyridyl complexes containing 2,2'‐bipyridine (bpy), 2,2'‐bipyrazine (bpz), 1,10‐phenanthroline (phen), 4,7‐diphenyl‐l,10‐phenanthroline (dip), 3,4,7,8‐tetramethyl‐l,10‐phenanthroline (tmp), 1,4,5,8‐tetraazaphenanthrene (tap), and 1,4,5,8,9,12‐hexaazatriphenylene (hat) with calf thymus DNA and poly(dA‐dT)‐poly(dA‐dT) (pdAT) has been investigated by steady‐state spectroscopy and emission lifetime measurements. Those complexes containing two or more tap/hat ligands photo‐oxidize the guanine base upon binding to DNA with efficiencies that parallel their excited state redox potentials, but display “normal” behavior (increase of both the emission intensity and lifetime) when bound to pdAT. However Ru(tap)(hat)22+ and Ru(hat)23+ even photooxidize the adenine base of pdAT, so that their excited states are also quenched in the presence of either polynucleotide. The electron transfer quenching mechanism has been confirmed previously by detection of the monoreduced complex in laser flash photolysis experiments in the presence of mononucleotides. Most of the complexes investigated appear to bind to DNA, at least in part via intercalation, with affinities being dependent on the nature of the largest ligand (hat shows the highest ability in heteroleptic complexes). From lifetime quenching experiments, in the presence of moderate amounts of NaCl, surface binding does not appear to be a general mode for the complexes investigated, and it has been demonstrated unequivocally only for Ru(phen)23+. In addition, the intercalation of complexes into DNA increases as the ionic strength of the medium decreases, the DNA/Ru ratio increases, or when water is partially replaced by glycerol.
UVB‐INDUCED PHOTOPEROXIDATION OF LIPIDS OF HUMAN LOW and HIGH DENSITY LIPOPROTEINS. A POSSIBLE ROLE OF TRYPTOPHAN RESIDUES
Authors: Salmon S. , Maziere J. C. , Santus R. , Morliere P. , Bouchemal N.
Published: January 2008

Abstract— Ultraviolet radiation of the UVB region readily destroy tryptophan (Trp) residues of low (LDL) and high (HDL) density lipoproteins. The photooxidation of tryptophan residues is accompanied by the peroxidation of low and high density lipoproteins unsaturated fatty acids, as measured by the thiobarbituric acid assay. Moreover, low and high density lipoproteins are natural carriers of vitamin E and carotenoids. These two antioxidants are also rapidly bleached by UVB. The UVA radiation promotes neither tryptophan residue destruction nor lipid photoperoxidation. The redox cycling Cu2+ ions considerably increase lipid photoperoxidation. The synergistic action of photo and auto (Cu2+‐induced) peroxidation induces marked post‐irradiation modifications of apolipoproteins as illustrated by the degradation of most tryptophan residues after overnight incubation in the dark of pre‐irradiated samples.
LIGHT‐DEPENDENT CYTOTOXIC REACTIONS OF ANTHRACENE
Authors: Tuveson R. W. , Wang Gui‐Rong , Wang Tian P. , Kagan Jacques
Published: January 2008

Abstract— Anthracene is a photodynamic compound in vitro. In the presence of oxygen, it is known to generate singlet oxygen and participate in Type II reactions. In aqueous solution, it also participates in Type I reactions, such as in the photoreduction of cytochrome c, which can be suppressed by superoxide dismutase. In argon, direct photoreduction of cytochrome c also takes place. Anthracene induces the photodynamic hemolysis of human erythrocytes and inactivates Escherichia coli cells photodynamically. By using a series of E. coli strains differing in DNA repair capabilities and catalase proficiency, sensitivity to inactivation by anthracene plus NUV was correlated with catalase deficiency rather than with particular repair deficiencies. The fact that carotenoid genes cloned and expressed in E. coli offered partial protection suggests that the membrane may be one possible target for inactivation by anthracene plus NUV. Anthracene plus NUV inactivated Haemophilus influenzae transforming DNA and led to nicking of supercoiled pBR322 DNA in vitro. In vivo, therefore, anthracene is a phototoxic molecule whose cytotoxicity could be the result of damage to more than one target.
PHOTOCHEMISTRY OF DNA USING 193 nm EXCIMER LASER RADIATION
Authors: Kochevar Irene E. , Buckley Lisa A.
Published: January 2008

Photoproducts in double‐stranded DNA induced by 193 nm radiation have been investigated. Double‐stranded, supercoiled pBR322 DNA in buffered aqueous solution was exposed to varying fluences of 193 nm radiation from an ArF excimer laser. The quantum yields for formation of cyclobutylpyrimidine dimers, frank strand breaks and alkali labile sites were calculated from the conversion of supercoiled (Form I) DNA to relaxed (Form II) DNA after treatment withMicrococcus luteusdimer‐specific endonuclease, no treatment, or treatment with alkali and heat, respectively. The quantum yields were 1.65 (± 0.03) × 10−3for pyrimidine dimers, 9.4 (± 3.2) × 10−5for frank strand breaks and 9.6 (± 3.6) × 10−5for alkali labile sites. The quantum yields for pyrimidine dimers and frank strand breaks were independent of Tris buffer and EDTA concentrations. The yields of frank strand breaks and alkali labile sites were not affected by 10mMmannitol. The relative quantum yields for these DNA photoproducts induced by 193 nm radiation differed markedly from those produced by 254 nm radiation.
INVESTIGATIONS ON THE FLUORESCENCE CONCENTRATION QUENCHING OF FLAVOMONONUCLEOTIDE IN GLYCERINE‐WATER SOLUTIONS
Authors: Grajek H. , Zurkowska G. , Bojarski C. , Drabent R.
Published: January 2008

We measured concentration changes of the fluorescence quantum yield η/ηo of flavomononucleotide (FMN) in glycerine‐water solutions of various viscosities. The results obtained show that FMN dimers are traps for the exciting light energy as well as the energy transferred non‐radiatively. Very good agreement between the experimental and theoretical η/ηo results was obtained. It has been shown that in the investigated solutions non‐radiative energy transfer from monomers to dimers takes place, preceded by the migration of energy. It has been stated that no monomer quenching occurs in these solutions. The contribution of the individual fluorescence concentration quenching mechanisms has been determined.
ERYTHROPOIETIC PROTOPORPHYRIA: PHOTODYNAMIC TRANSFER OF PROTOPORPHYRIN FROM INTACT ERYTHROCYTES TO OTHER CELLS
Authors: Brun Atle , Western André , Malik Zvi , Sandberg Sverre
Published: January 2008

Erythrocytes in patients with erythropoietic protoporphyria (EPP) contain large amounts of protoporphyrin and are regarded as the main source of protoporphyrin in this disease. Cells in the skin of EPP patients accumulate protoporphyrin released from the erythrocytes and upon sun exposure endothelial cells are photodamaged. In the present study a light‐induced transfer of protoporphyrin directly from EPP erythrocytes to cultured cells is demonstrated. Erythrocytes were layered upon cultured cells and irradiated. The nearness of erythrocyte and cultured cell membranes potentiated the transfer of protoporphyrin between these cells. This transfer was rapid and preceded the release of protoporphyrin to proteins in the medium. Further irradiation of the protoporphyrin‐enriched cultured cells, after removal of the erythrocytes, caused severe photodamage to the cells and survival was dependent on both the amount of protoporphyrin transferred and on the light fluence. Clinical observations and the results of this study indicate that light energy may be involved in two steps in the pathophysiology of EPP: (A) light‐induced release of protoporphyrin from erythrocytes to endothelial cells and (B) photodynamic damage to protoporphyrin‐enriched endothelial cells.
IMMEDIATE PIGMENT DARKENING: VISUAL AND REFLECTANCE SPECTROPHOTOMETRIC ANALYSIS OF ACTION SPECTRUM
Authors: Rosen Cheryl F. , Jacques Steven L. , Stuart Mary E. , Gange Richard W.
Published: January 2008

Immediate pigment darkening (IPD) occurs in human skin upon exposure to ultraviolet‐A and visible radiation. The spectral changes that occur during IPD were measured with a rapid scanning reflectance spectrophotometer (RS) which employs optical fiber bundles for delivery and detection of light between 400 and 750 nm. The radiation dose dependence and wavelength dependence (334–549 nm irradiation) of IPD were studied by both the classical visual grading method and by spectrophotometric scoring using the RS system. The spectral changes that occur at long wavelengths with IPD mimic the natural absorption spectrum of melanin. Therefore, the IPD was scored in terms of the apparent change in melanin optical density, using the method Kollias and Baqer [Photochem. Photobiol. 43,49–54 (1986)], based on reflectance in the620–720 nm range. The nonlinearity of the visual grading method is demonstrated. The degree of IPD is first‐order with respect to delivered dose and saturates after high doses. The maximum amount of IPD attained at saturation is greater for shorter wavelengths. Extrapolation of the reflectance data suggests the longest wavelength capable of eliciting IPD is about 470 nm.
CELL MEMBRANE DNA: A NEW TARGET FOR PSORALEN PHOTOADDUCT FORMATION
Authors: GASPARRO F.P. , DALL'AMICO R. , O'MALLEY M. , HEALD P.W. , EDELSON R.L
Published: January 2008

Abstract—

The effects of 8‐methoxypsoralen plus long wavelength ultraviolet radiation on cell membrane DNA were examined. Treatment of human lymphocytes with 100 ng/ml 8‐methoxypsoralen and 5 J/cm2 UVA led to the formation of 7.1 ±3.8 photoadducts per million bases. A monoclonal antibody, specific for 8‐methoxypsoralen 4′,5′4nonoadducts, was used to detect photoadducts in the cell membrane DNA of human lymphocytes and three lymphoblastoid cell lines. Treatment of lymphocytes with 8‐MOP and UVA reduced the lymphocyte DNA binding capacity by 56%. Cell membranes of normal lymphocytes were shown to contain three high affinity DNA binding proteins of 28, 59, and 79 kDa, respectively.
THE USE OF FLUORESCENT PROBES IN IMMUNOCHEMISTRY*
Authors: Davidson R. Stephen , Hilchenbach Martin M.
Published: January 2008

Abstract—

The limitations and advantages of particular dyes for labelling proteins and other biological materials are discussed. Methods available for conjugating dyes to proteins are outlined. Following a discussion of double labelling methods the use of photoactivatable fluorochromes and time resolved fluorescence methodologies are outlined. The reasons for the photoinstability of some fluorochromes are discussed and methods for overcoming the problem are described.
THE COMPLEXES FORMED BY BILADIENE a, b COMPOUNDS WITH ZINC IONS and THEIR APPLICATION IN DETERMINATION OF THE CHROMOPHORE COMPOSITION OF α‐ and β‐ SUBUNITS OF R‐PHYCOERYTHRIN
Authors: Cheng Ling‐Jiang , Ma Jin‐Shi , Jiang) Li‐Chin Chiang (Li‐Jin
Published: January 2008

Abstract— –Phycoerythrobilin dimethyl ester (PEBDM) or isomesobiliviolin dimethyl ester (IBVDM) formed complexes with zinc ions in chloroform. The complex ratios were determined to be 1:1 according to the spectrophotometric titration of PEBDM and IBVDM with zinc ions in methanol and the mass spectra of the complexes. The chromophore compositions of R‐phycoerythrin from Porphyra yezoensis were determined by spectrophotometric titration of α‐ and β‐subunits at pH 13.0 with zinc ions. There were 2 phycoerythrobilins in the a‐subunit, and 1 phycourobilin and 3 phycoerythrobilins in the β‐subunit.
CELLULAR UPTAKE AND RELATIVE EFFICIENCY IN CELL INACTIVATION BY PHOTO ACTIVATED SULFONATED meso‐TETRAPHENYLPORPHINES
Authors: Berg Kristian , Bommer Jerry C. , Winkelman James W. , Moan Johan
Published: January 2008

Abstract—The cellular uptake, relative fluorescence quantum yields and photosensitizing efficiencies of meso‐tetraphenylporphines sulfonated to different degrees (TPPSn) have been investigated using the human carcinoma cell line NHIK 3025. The efficiencies of these dyes in photoinactivation of cells were highly dependent on the number of sulfonate groups on the derivatives. These differences in phototoxicity were primarily due to different abilities to be taken up by cells, but were also dependent upon the cellular localization of the dyes. TPPS1and TPPS2awere more efficiently taken up by the cells than TPPS2oand TPPS4. Plasma membrane associated TPPS4was less efficient in cell inactivation per quantum of fluorescence emitted than intracellularly located dye. This was also to some extent the case for TPPS1but not for TPPS2aand TPPS2o. The results presented here indicate that TPPS2aand TPPS1are the most promising of the TPPSns for possible future use in photodynamic therapy.
DNA BREAKS CAUSED BY MONOCHROMATIC 365 nm ULTRAVIOLET‐A RADIATION OR HYDROGEN PEROXIDE and THEIR REPAIR IN HUMAN EPITHELIOID and XERODERMA PIGMENTOSUM CELLS
Authors: Peak Jennifer G. , Pilas Barbara , Dudek Edward J. , Peak Meyrick J.
Published: January 2008

The induction and repair of DNA single‐strand breaks (SSB) assayed by alkaline filter elution was compared in human epithelioid P3 and xeroderma pigmentosum (XP) cells exposed to monochromatic 365‐nm UV‐A radiation and H2O2. Initial yields of SSB were measured with the cells held at 0.5°C during exposure. The yield from exposure to 365‐nm radiation was slightly greater in XP than in P3 cells, whereas H2O2 produced more than three times as many SSB in P3 compared with XP cells. o‐Phenanthroline (50 mM) markedly inhibited the yields of SSB induced in XP cells by H2O2, but had no effect on those produced by 365‐nm UV‐A. These results are consistent with the fact that P3 cells, unlike XP cells, have undetectable levels of catalase. The measured production of trace amounts of H2O2 by the actual 365‐nm UV‐A exposures was not sufficient to account for the numbers of breaks that were observed. Single‐strand breaks produced by both agents were completely repaired after 50 min in P3 cells, as were H2O2‐induced SSB in XP cells. However, 25% of the 365‐nm UV‐A‐induced SSB in XP cells remained refractory to repair after 60 min. The results show that SSB produced by these two agents are different and that 365 nm radiation produces most SSB in cells by mechanisms other than by production of H2O2.
BIOCHEMICAL CHANGES IN HAIRLESS MOUSE SKIN COLLAGEN AFTER CHRONIC EXPOSURE TO ULTRAVIOLET‐A RADIATION*
Authors: Kligman Lorraine H. , Gebre Michele
Published: January 2008

Evidence is mounting that UV‐B and UV‐A radiation affect skin differently in responses as diverse as erythema and elastosis. We found in this study that collagen metabolism was also differentially affected. Albino hairless mice were irradiated with two UV‐A sources: (1) UVASUN 3000 (340–400nm) for cumulative exposures of 4000 and 8000 J/cm2; (2) a xenon solar simulator filtered to provide full spectrum UV‐A (320–400nm) and long wavelength UV‐A (335–400nm) for cumulative exposures of 3000 and 4000 J/cm2 respectively. Collagen was isolated from other skin proteins by acid extraction, pepsin digestion and salt precipitation. Collagen types I and III were separated by interrupted gel electrophoresis. Ultraviolet‐A rendered the collagen highly resistant to pepsin digestion. In age‐matched controls only16–18% of the total collagen remained insoluble, whereas in long wavelength UV‐A‐irradiated skins the insoluble fraction was as high as 87%. A dose response was noted at 4000 and 8000 J/cm2 as delivered by the UVASUN. Recovery of collagen from the pepsin soluble fraction was low in all UV‐A groups and the amount of type III so small that determination of ratios of type III to I collagen was unreliable. These results suggest that chronic UV‐A radiation may increase cross‐linking of dermal collagen.
THE PHOTO‐OXIDATION OF N, N‐DIETHYLHYDROXYLAMINE BY ROSE BENGAL IN ACETONITRILE AND WATER
Authors: Bilski P. , Li A.S.W. , Chignell C.F.
Published: January 2008

The Rose Bengal photosensitized oxidation of N,N‐diethylhydroxylamine has been investigated in water and acetonitrile using the techniques of oxygen uptake, singlet oxygen phosphorescence and electron spin resonance. In both solvents H2O2 is the major oxidation product and diethylnitroxide is an intermediate. In water, superoxide dismutase decreases oxygen uptake suggesting involvement of superoxide anions in the oxidation process. Results indicate that in water the photo‐oxidation proceeds mainly by a Type I(electron transfer) mechanism, while in acetonitrile a Type II(energy transfer) mechanism has been confirmed (Encinas et al., 1987, J. Chem. Soc. Perkin Trans. II,1125–1127).
ROOM‐TEMPERATURE FLUORESCENCE PROPERTIES OF THE POLYNUCLEOTIDE POLYdA POLYdT
Authors: Ge G. , Georghiou S.
Published: January 2008

The room‐temperature fluorescence spectrum of the non‐alternating polynucleotide polydA‐polydT is found to have its maximum at about 325 nm and, when exciting in the spectral region where both adenine (A) and thymine (T) absorb, to coincide with that obtained for excitation at 293 nm where thymine is selectively excited. The fluorescence anisotropy is found to be equal to 0.18 and independent of the excitation and emission wavelengths. These observations are consistent with: (i) emission stemming from T; and (ii) transfer of electronic energy from A to T being not efficient. These inferences are also supported by the observed dependence of the fluorescence quantum yield on the excitation wavelength.
ACTION SPECTRA AGAIN?*
Authors: Coohill Thomas P.
Published: January 2008

Action spectroscopy has a long history and is of central importance to photobiological studies. Action spectra were among the first assays to point to chlorophyll as the molecule most responsible for plant growth and to DNA as the genetic material. It is useful to construct action spectra early in the investigation of new areas of photobiological research in an attempt to determine the wavelength limits of the radiation region causing the studied response. But due to the severe absorption of ultraviolet (UV) radiation by biological samples, UV action spectra were first limited to small cells (bacteria and fungi). Advances in techniques(e.g.single cell culture) and analysis allowed accurate action spectra to be reported even for mammalian cells. But precise analytical action spectra are often difficult to obtain when large, pigmented, or groups of cells are investigated. Here some action spectra are limited in interpretation and merely supply a wavelengthvseffect curve. When polychromatic sources are employed, the interpretation of action spectra is even more complex and formidable. But such polychromatic action spectra can be more directly related to ambient responses. Since precise action spectra usually require the completion of a relatively large number of careful experiments using somewhat sophisticated equipment over a range of at least six wavelengths, they are often not persued. But they remain central to the elucidation of the effect being studied. The worldwide community has agreed that stratospheric ozone is depleting, with the possibility of a consequent rise in the amount of UV‐B (290–320nm) reaching the earth's surface. It is therefore essential that new action spectra be completed for UV‐B effects on a large variety of responses of human, animal, and aquatic plant systems. Combining these action spectra with the known amounts of UV‐B reaching the biosphere can give rise to solar UV effectiveness spectra that, in turn, can give rise to estimates of effect. Preliminary estimates suggest that ozone layer depletion may seriously impact such important biological end‐points as skin cancer, cataracts, the immune system, crop yields, and oceanic phytoplankton. So action spectra continue to play a central role in important photobiological research.
BATHOPRODUCTS and CONFORMERS OF ALL‐trans‐AND 13‐ds BACTERIORHODOPSIN AT 90 K*
Authors: Balashov S. P. , Karneyeva N. V. , Litvin F. F. , Ebrey T. G.
Published: January 2008

Abstract– At 90 K the photoproduct of the primary light reaction of (rani‐bacteriorhodopsin, the bathoproduct K1 consists of a mixture of at least three spectrally different species, K1I, K1II, and K1III having maxima in the difference absorption spectra at 645, 635 and 625 nm, respectively. The bathoproducts differ in their long wavelength absorption bands and in their rate constants for photo‐conversion to trans‐bacteriorhodopsin under far red light irradiation (λ > 720 nm). The bathoproducts are formed from different precursors–conformers of trans‐bacteriorhodopsin, which are stable at 90 K, but are in equilibrium with each other at 213 K. We suggest that the bathoproducts may initiate parallel conversion cycles of trans‐bacteriorhodopsin at low temperatures. The primary photoreaction of 13‐cis‐bacteriorhodopsin also yields three bathoproducts, KcI, KcII and KcIII having maxima in the difference absorption spectra at 615, 605 and 595 nm, respectively.
ISOMER COMPOSITION and SPECTRA OF THE DARK and LIGHT ADAPTED FORMS OF ARTIFICIAL BACTERIORHODOPSINS*
Authors: Steinberg G. , Friedman N. , SHEVES M. , Ottlenghi M.
Published: January 2008

Abstract– The isomer composition and spectral properties of 15 artificial bacteriorhodopsin (bR) pigments, based on a series of retinal analogs with polyene residue modified below C9 are determined for both dark‐adapted (DA) and light‐adapted (LA) forms. Similarly to native bR, in all cases only two isomers, C13=C14cis (13‐cis) and M‐trans, are observed. However, the artificial DA pigments have a lower 13‐d.s content than native DA bR (˜ 66%) while the corresponding LA pigments have a much higher 13‐cis content (11‐69%) than native LA bR (<2%). Thus, in variance with the native pigment, in all of the artificial systems light also induced the reversed all‐trans13‐cis process. The data are accounted for in terms of specific steric interactions between the polyene and the protein binding site which allow a (C15‐anti)(Cls‐syn) isomerization during the photocycle of the artificial pigments, but not in the case of native bR. This accounts for the high proton pumping efficiency of the natural pigment.

The nature of a highly red shifted light‐adapted form of two of the artificial pigments is investigated and discussed. It is also shown that, in variance with native bR, several artificial pigments exhibit identical absorption spectra for their 13‐cis and all‐trans isomers. It is concluded that the spectral data for the above species of artificial pigments do not lead to a clear molecular model for the origin of the spectral shift between 13‐cis and all‐trans bR.
A RESONANCE RAMAN STUDY OF OCTOPUS BATHORHODOPSIN WITH DEUTERIUM LABELED RETINAL CHROMOPHORES*
Authors: Deng H. , Manor D. , Weng G. , Rath P. , Koutalos Y. , Ebrey T. , Gebhard R. , Lugtenburg J. , Tsuda M. , Callender R. H.
Published: January 2008

Abstract– The resonance Raman spectrum of octopus bathorhodopsin in the fingerprint region and in the ethylenic‐Schiff base region have been obtained at 80 K using the “pump‐probe” technique as have its deuterated chromophore analogues at the C7D; C8D; C7, C8D2; C10D; C11,D; C11, C12D2; C14D; C15D; C14, C15D2; and N16D positions. While these data are not sufficient to make definitive band assignments, many tentative assignments can be made. Because of the close spectral similarity between the octopus bathorhodopsin spectrum and that of bovine bathorhodopsin, we conclude that the essential configuration of octopus bathorhodopsin's chromophore is all‐trans like. The data suggest that the Schiff base, C=N, configuration is trans (and). The observed conformationaly sensitive fingerprint bands show pronounced isotope shifts upon chromophore deuteration. The size of the shifts differ, in certain cases, from those found for bovine bathorhodopsin. Thus, the internal mode composition of the fingerprint bands differs somewhat from bovine bathorhodopsin, suggesting a somewhat different in situ chromophore conformation. An analysis of the NH bend frequency, the Schiff base C=N stretch frequency, and its shift upon Schiff base deuteration suggests that the hydrogen bonding between the protonated Schiff base with its protein binding pocket is weaker in octopus bathorhodopsin than in bovine bathorhodopsin but stronger than that found in bacteriorhodop‐sin's bR568 pigment.
QUANTUM YIELD OF CHAPSO‐SOLUBILIZED RHODOPSIN and 3‐HYDROXY RETINAL CONTAINING BOVINE OPSIN*
Authors: Gärtner W. , Ullrich D. , Vogt K.
Published: January 2008

Abstract–The quantum yields of bleaching for two artificial pigments, bovine opsin combined with (3ft)‐3‐hydroxy retinal or (3R,S)‐3‐methoxy retinal, were determined in comparison to the value for regenerated bovine rhodopsin. Regeneration of the visual pigments was performed by incubation of 3‐[(3‐Cholamidopropyl)‐dimethylammonio]‐2‐hydroxy‐1‐propanesulfonate (CHAPSO)‐solubilized opsin with the 11‐cisisomers of retinal and the respective retinal derivatives. The extinction coefficients of the pigments in CHAPSO were determined to 35000M−1cm−1(native rhodopsin), 35300M−1cm−1(regenerated rhodopsin) and 34500M−1cm−1(3‐OH retinal opsin). With respect to rhodopsin (Λmax: 500 nm), the pigments carrying the substituted chromophores exhibit blue shifted absorbance maxima (3‐hydroxy and 3‐methoxy retinal opsin: 488 nm). In parallel experiments under absolutely identical conditions we find related to the value of CHAPSO solubilized rhodopsin (1) a quantum efficiency of bleaching for the 3‐hydroxy pigment of 1.2.
IODOPSIN, A RED‐SENSITIVE CONE VISUAL PIGMENT IN THE CHICKEN RETINA*
Authors: Yoshizawa Tocru , Kuwata Osamu
Published: January 2008

Abstract–The vertebrate retina contains two kinds of visual cells: rods, responsible for twilight (scotopic) vision (black and white discrimination); and cones, responsible for daylight (photopic) vision (color discrimination). Here we attempt to explain some of their functional differences and similarities in terms of their visual pigments. In the chicken retina there are four types of single cones and a double cone; each of the single cones has its own characteristic oil droplet (red, orange, blue, or colorless) and the double cone is composed of a set of principal and accessory members, the former of which has a green‐colored oil droplet. Iodopsin, the chicken red‐sensitive cone visual pigment, is located at outer segments of both the red single cones and the double cones, while the other single cones and the rod contain their own visual pigments with different absorption spectra. The diversity in absorption spectra among these visual pigments is caused by the difference in interaction between chromophore (11‐cisretinal) and protein moiety (opsin). However, the chromophore‐binding pocket in iodopsin is similar to that in rhodopsin. The difference in absorption maxima between both pigments could be explained by the difference in distances between the protonated Schiff‐bases at the chromophore‐binding site and their counter ions in iodopsin and rhodopsin. Furthermore, iodopsin has a unique chloride‐binding site whose chloride ion serves for the red‐shift of the absorption maximum of iodopsin. Visual pigment bleaches upon absorption of light through several intermediates and finally dissociates into all‐transretinal and opsin. That the sensitivity of cones is lower than rods cannot be explained by the relative photosensitivity of iodopsin to rhodopsin, but may be understood to some extent by the short lifetime of an enzymatically active intermediate (corresponding to metarhodopsin II) produced in the photobleaching process of iodopsin. The rapid formation and decay of the meta II‐intermediate of iodopsin compared with metarhodopsin II are not contradictory to the rapid generation and recovery of cone receptor potential compared with rod receptor potential. The rapid recovery of the cone receptor potential may be due to a more effective shutoff mechanism of the visual excitation, including the phosphorylation of iodopsin. The rapid dark adaptation of cones compared with rods has been explained by the rapid regeneration of iodopsin from 11‐cisretinal and opsin. One of the reasons for the rapid regeneration and susceptibility to chemicals of iodopsin compared with rhodopsin may be a unique structure near the chromophore‐binding site of iodopsin.
CELLULAR DELIVERY AND RETENTION OF PHOTOFRIN II: THE EFFECTS OF INTERACTION WITH HUMAN PLASMA PROTEINS
Authors: KORBELIK MLADEN , HUNG JACLYN
Published: January 2008

Abstract—

The absorbance and fluorescence spectra of Photofrin II (PII) in the presence of albumin, globulins and lipoproteins from human plasma show that all of these proteins induce a degree of disaggregation of PII material. In addition, there are substantial rearrangements in the distribution of different fractions contained in PII and their binding to the protein. It is shown that these rearrangements have considerable impact on the uptake of PII by cultured cells and the ensuing retention of the drug in the cells. The information on the contribution of fluorescing and non‐fluorescing components of PII in the cells was obtained by measuring first the PII fluorescence in suspensions of live cells, followed by chemical extraction of porphyrin material from the same cells. The interaction of PII with low density lipoproteins resulted in markedly lower levels of PII material retained in the cells, compared to protein‐free drug exposure. Somewhat better but still inferior PII retention was observed with high density lipoproteins. The samples with very low density lipoproteins showed increased uptake of PII, but the subsequent retention of the drug was low, so that the remaining amount of the drug was not much different than in protein‐free samples. The strongest inhibition of PII uptake was seen with albumin, with ensuing retention of PII not significantly different than in protein‐free samples. The best retention of PII was observed with globulins, with approx. 25% higher total drug content retained in the cells after long‐term clearance relative to protein‐free samples.
ARE THE EFFECTS OF LIGHT ON PHASE AND PERIOD OF THE Gonyaulax CLOCK MEDIATED BY DIFFERENT PATHWAYS?
Authors: ROENNEBERG TILL , HASTINGS J. WOODLAND
Published: January 2008

Abstract—

The effects of different wavelengths of light on period, phase shifting, entrainment and after‐effects of the circadian clock of the motile marine dinoflagellate Gonyaulax polyedra are described. Phase shifting and entrainment by light can be explained by the action of a single blue sensitive light input pathway. However, tonic effects of light on the period under free‐running conditions, and also after‐effects on period resulting from single 4 h light exposures, appear to involve two input pathways with different absorption and temperature characteristics. These results suggest different mechanisms for the control of phase and period of the circadian clock.
PHOTOSENSITIZATION IS REQUIRED FOR INACTIVATION OF EQUINE INFECTIOUS ANEMIA VIRUS BY HYPERICIN
Authors: CARPENTER SUSAN , KRAUS GEORGE A.
Published: January 2008

Abstract—Hypericin, a photoreactive polycyclic quinone, was found to dramatically reduce infectivity of cell‐free stocks of equine infectious anemia virus. However, the antiviral activity of hypericin was completely dependent on the presence of light. Short periods of photosensitization resulted in a partial loss of reverse transcriptase activity and complete inhibition of viral infectivity. These results suggest that the photodynamic effect of hypericin interferes with more than one stage in the virus replication cycle.
MEMBRANE PHOTOMODIFICATION OF CARDIAC MYOCYTES: POTASSIUM AND LEAKAGE CURRENTS
Authors: VALENZENO DENNIS PAUL , TARR MERRILL
Published: January 2008

Abstract— Cardiac myocytes were isolated from the atria of frogs (Rana pipiens) and whole cell potassium (Ik) and “leakage” (Ilcak) currents were monitored using the patch clamp technnique. Cells were photosensitized by exposure to Rose Bengal (0.125–0.5 μM). Illumination produced an exponential decrease in Ik, and an increase in Ileak. Current modifications varied with light intensity and sensitizer concentration. Ik stabilized when illumination ceased, while Ilcak continued to increase at a slower rate after illumination ended. The exponential nature of Ik modification suggests that potassium channels are photomodified with single hit kinetics. The stabilization of Ik following illumination suggests (1) that the photomodification of the potassium channel does not involve long lasting (minutes) radical chain reactions and (2) that this photomodification is not repaired in the course of a few minutes.
CORRELATION BETWEEN CELL SURVIVAL AND DNA SINGLE‐STRAND BREAK REPAIR PROFICIENCY IN THE CHINESE HAMSTER OVARY CELL LINES AA8 AND EM9 IRRADIATED WITH 365‐nm ULTRAVIOLET‐A RADIATION
Authors: CHURCHILL MARK E. , PEAK JENNIFER G. , PEAK MEYRICK J.
Published: January 2008

Abstract— Cell survival parameters and the induction and repair of DNA single‐strand breaks were measured in two Chinese hamster ovary cell lines after irradiation with monochromatic UVA radiation of wavelength 365 nm. The radiosensitive mutant cell line EM9 is known to repair ionizing‐radiation‐induced single‐strand breaks (SSB) more slowly than the parent line AA8. EM9 was determined to be 1.7‐fold more sensitive to killing by 365‐nm radiation than AA8 at the 10% survival level, and EM9 had a smaller shoulder region on the survival curve (α= 1.76) than AA8 (α= 0.62). No significant differences were found between the cell lines in the initial yields of SSB induced either by γ‐radiation (as determined by alkaline sucrose gradient sedimentation) or by 365‐nm UVA (as determined by alkaline elution). For measurement of initial SSB, cells were irradiated at 0.5°C to minimize DNA repair processes. Rejoining of 365‐nm induced SSB was measured by irradiating cells at 0.5°C, allowing them to repair at 37°C in full culture medium, and then quantitating the remaining SSB by alkaline elution. The repair of these breaks followed biphasic kinetics in both cell lines. EM9 repaired the breaks more slowly (t1/2 values of 1.3 and 61.3 min) than did AA8 (t1/2 values of 0.9 and 53.3 min), and EM9 also left more breaks unrepaired 90 min after irradiation (24% vs 8% for AA8). Thus, the sensitivity of EM9 to 365‐nm radiation correlated with its deficiency in repairing DNA lesions revealed as SSB in alkaline elution. These results suggest that DNA may be a critical target in 365‐nm induced cellular lethality and that the ability of AA8 and EM9 cells to repair DNA strand breaks may be related to their ability to survive 365‐nm radiation.
ANALOGS AND DERIVATIVES OF FIREFLY OXYLUCIFERIN, THE LIGHT EMITTER IN FIREFLY BIOLUMINESCENCE
Authors: WHITE EMIL H. , ROSWELL DAVID F.
Published: January 2008

Abstract— The 5‐methyl analog of firefly oxyluciferin, two isomeric O‐methyl ether derivatives of it and an O, OÓ‐dimethyl ether derivative were synthesized and their UV absorption and fluorescence emission spectra were determined. Comparisons of the emission data with the emission wavelength in bioluminescence indicate that the mono‐anions of firefly oxyluciferin are candidates for the light‐emitters in bioluminescence. Further, we have found that the chemiluminescence of active esters of firefly luciferin produces (from the keto form of oxyluciferin) only red light emission under a variety of conditions; a yellow‐green light emission (from the enolic forms of the oxyluciferin product) could not be elicited.
EXTRACTION OF RETINAL FROM Paramecium bursaria
Authors: TOKIOKA RYO , MATSUOKA KOHJI , NAKAOKA YASUO , KITO YUJI
Published: January 2008

Abstract— The ciliated protozoan Paramecium bursaria is photosensitive. Retinal, which is the chromophore of the visual pigments of many multicellular animals, was extracted from P. bursaria and identified by HPLC. The procedure of identification was based on the change in polarity achieved by reducing retinal with sodium borohydrate to form retinol. This method is useful for the detection of small amounts of retinal in cells containing large amounts of other substances with similar polarity. The presence of retinal in P. bursaria suggests that this ciliate may contain a photoreceptor pigment with retinal as the chromophore.
PSORALEN‐PHOTOSENSITIZED DAMAGE OF RAT PERITONEAL EXUDATE CELLS
Authors: KYAGOVA A. A. , KORKINA L. G. , SNIGIREVA T. V. , LYSENKO E. P. , TOMASHAEVA S. K. , POTAPENKO A. YA.
Published: January 2008

Abstract— Psoralen‐sensitized photodamage (PUVA) of rat peritoneal exudate cells was investigated. Quartz‐activated luminol‐dependent chemiluminescence (ChL) was registered and the amount of trypan‐positive cells was determined.

Irradiation of peritoneal exudate cells in the presence of psoralen resulted in a dose‐dependent monotonous inhibition of ChL. The reciprocity law of irradiation intensity and duration of irradiation was not valid for the observed inhibition of ChL; the inhibition increased with higher intensity.

When psoralen previously photooxidized in ethanol (POP) was added to peritoneal exudate cell suspension, a double‐phase response depending on psoralen irradiation dose was obtained: ChL activation was observed at low doses of UVA, ChL inhibition at high doses. Chemiluminescence inhibition correlated well with the increase in the number of trypan‐positive cells.

It may be supposed that the observed effects of PUVA or POP treatment are caused by cell cytoplasmic membrane damage.
THE EFFECT OF THE ANTIHISTAMINE CIMETIDINE ON ULTRAVIOLET‐RADIATION‐INDUCED TUMORIGENESIS IN THE HAIRLESS MOUSE
Authors: MATHESON MELISSA J. , REEVE VIVIENNE E.
Published: January 2008

Abstract— This experiment investigated the effect on ultraviolet (UV) radiation‐induced tumorigenesis of feeding the histamine type 2 receptor antagonist, cimetidine, to Skh:HR mice. Cimetidine was fed to one group during a 70 day period of chronic UVR (5 day/week for 10 weeks), to a second group from the end of this period to the end of the experiment at 286 days and a third group was fed a control diet only throughout the experiment. Feeding mice cimetidine during the 70 day period of irradiation protected them against the later development of skin tumours.
THE FORMATION OF A SHORT‐WAVELENGTH CHLOROPHYLLIDE FORM AT PARTIAL PHOTOTRANSFORMATION OF PROTOCHLOROPHYLLIDE IN ETIOPLAST INNER MEMBRANES*
Authors: BÖUDDI BELA , RYBERG MARGARETA , SUNDQVIST CHRISTER
Published: January 2008

Abstract—Partial phototransformation caused the formation and successive accumulation of spectral forms of chlorophyllide in etioplast inner membrane fractions from wheat (Triticum aestivumL. cv. Walde), Low‐temperature fluorescence emission and circular dichroism spectra showed the formation of two chlorophyllide forms with emission maxima at 683 and 694 nm, respectively. The light dependent accumulation of the two forms differed in prolamellar body (PLB) and prothylakoid (PT) fractions. The 694 nm form was preferentially found in PLB fractions which before irradiation were characterized by a 657 nm emitting protochlorophyllide form and a regular PLB structure. The 683 nm form accumulated to a higher extent in PT fractions which before irradiation contained mainly shortwavelength protochlorophyllide forms. The results indicate that at least two photoactive protochlorophyllide forms must be considered. The major part of protochlorophyllide, with a fluoresence emission maximum at 657 nm, is transformed to the 694 nm emitting chlorophyllide first at high light doses. A minor part, revealed only after Gaussian resolution, has a fluorescence emission maximum at 645 nm and was transformed by low light doses to chlorophyllide emitting at 683 nm.
CAROTENOID AND CONJUGATED POLYAMINE LEVELS AS INDICATORS OF ULTRAVIOLET‐C INDUCED STRESS IN Arabidopsis thaliana*
Authors: CAMPOS J. L. , FIGUERAS X. , PIöTOL M. T. , BORONAT A. , TIBURCIO A. F.
Published: January 2008

Abstract— We report that Arabidopsis thaliana plants irradiated with UC‐V (600 and 960 J m‐2; i= 10 and 16 W m‐2 respectively) show a retardation of growth and changes in pigment composition in a dose dependent manner. There is an increase in the carotenoid levels which is positively correlated with an enhancement of the 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase mRNA levels. The contents of perchloric‐acid soluble conjugated polyamines also increase and these are positively correlated with enhanced phenylalanine ammonia lyase mRNA levels. We propose carotenoid and conjugated polyamine levels as biochemical indicators of UV induced‐stress in plants.
EXPRESSION OF AP 3, 4 AND 5 ISOPHYTOCHROMES IN ETIOLATED OAT SEEDLINGS (Avena sativa L.)*
Authors: GRIMM RUDOLF , ECKERSKORN CHRISTOPH
Published: January 2008

Abstract— Type 1 phytochrome from etiolated oat seedlings was digested with V‐8 protease. Microsequencing of a 13 kDa fragment yielded a sequence of 31 amino acids. The fragment starting with the alanine residue at position 427 of the entire phytochrome amino acid sequence revealed a heterogeneity (threonine, alanine and asparagine) at position 10. This demonstrates that the phytochrome type A genes AP3, 4 and 5 are expressed as proteins.
PROTECTIVE ROLE OF BUTYLATED HYDROXYTOLUENE AND CERTAIN CAROTENOIDS IN PHOTOCARCINOGENESIS*
Authors: BLACK HOMER S. , MATHEWS‐ROTH MICHELINE M.
Published: January 2008

Abstract—Butylated hydroxytoluene (BHT) and certain carotenoid pigments have been found to inhibit photocarcinogenesis in animal models. In addition, BHT protects against UV‐B‐induced erythema and UV‐B induction of ornithine decarboxylase.

Studies on the photoprotective mechanism(s) of BHT suggested that changes in the physico‐chemical properties of the keratin of the stratum corneum layer of skin occurred, leading to increases in UV absorption of that tissue. These changes might be exertedviathe anti‐radical action of BHT that retards oxidation and prevents cross‐linking of the keratin chains, resulting in a diminution of UV‐B radiation reaching potential target sites.

The carotenoids β‐carotene, canthaxanthin and phytoene also inhibit UV‐B carcinogenesis. β‐Carotene and canthaxanthin are excellent quenchers of singlet oxygen, and all three pigments can quench free radicals. β‐Carotene and canthaxanthin have been shown to quench singlet oxygen/free radical reactions in the skin of porphyric mice, and these two pigments as well as phytoene have been found to quench excited species formed on irradiation of mouse skin by UV‐B.
SURFACE‐ENHANCED RESONANCE RAMAN SCATTERING SPECTROSCOPY AS A SURFACE TOPOGRAPHY PROBE IN PLANT PHOTOSYNTHETIC MEMBRANES
Authors: Picorel R. , Bakhtiari M. , Lu T. , Cotton T. M. , Seibert M.
Published: January 2008

Abstract—

Strong resonance Raman (RR) and surface‐enhanced resonance Raman scattering (SERRS) signals from carotenoids were detected from thylakoid (stromal‐side out) vesicles and inside‐out (lumenal‐side out) vesicles isolated from spinach chloroplasts. The intensity of the signals from both types of membranes was comparable, indicating that plant carotenoids are exposed on or close to both surfaces or sides of the thylakoid membrane. This is in contrast to previous studies with bacterial photosynthetic membranes (Picorel et al., 1988, J. Biol. Chem. 263, 4374–4380; and 1990, Biochemistry29, 707–712) that show carotenoids selectively located on the cytoplasmic side. In addition; strong RR and SERRS signals were detected from stacked and unstacked photosystem‐II‐enriched membrane fragments, demonstrating that carotenoids are also exposed on both surfaces of the appressed region of the thylakoid membrane. Antibodies against the photosystem (PS) II extrinsic proteins blocked SERRS signals from stacked PS II membrane fragments, but only partially affected the SERRS signals from unstacked membranes. The results indicate that these antibodies, which preferentially cover the surface of the original lumenalside of the appressed region, act as spacers between the membrane and SERRS electrode surfaces. The original stromal‐side of the appressed region is unaffected. These findings verify the distance sensitivity of the SERRS technique and underscore the above conclusion about the location of carotenoids in the appressed regions. Finally, SERRS signals are sensitive to membrane aging and storage temperature; caution is suggested to those applying SERRS spectroscopy to intact membrane systems.