bluuebunny/crossref_metadata_2025 huggingface dataset:
ROSE BENGAL AGGREGATION IN RATIONALLY SYNTHESIZED DIMERIC SYSTEMS
Authors: Luttrull David K. , Valdes‐Aguilera Oscar , Linden Shwn Meei , Paczkowski Jerzy , Neckers D. C.
Published: January 2008

Abstract— Rose Bengal derivatives (I‐VI) have been synthesized as part of a program to study the spectroscopy of model systems for Hpd dimer. The absorption and emission spectra as a function of solvent are diagnostic for the formation of aggregated conformers. Based on our spectroscopic results we conclude that these compounds exist in open conformation in ethanol and other organic solvents, and that they form intramolecular dimers in aqueous solution.
THE ROLE OF HEMOGLOBIN IN THE PHOTOTAXIS OF THE NEMATODE Mermis nigrescens
Authors: Burr A. H. (Jay) , EGGLETON DAVID K. , PATTERSON ROBERT , LEirrscHER‐HAZELHOFF JOHANNA T.
Published: January 2008

Abstract A dense zone of crystalline hemoglobin in the head has been presumed to be involved in the photosensitivity of Mermis. With the aim of identifying its role, we have studied the wavelength dependence of the phototaxis. Measuring phototaxic efficiency at constant photon fluence rate (intensity), we find that the spectral response curve is approximately fiat from 350–540 nm and falls to an insignificant level by 580 nm. This is unlike the absorptance (fraction absorbed) spectrum of the hemoglobin pigmentation. Also, fluence‐rate/response curves at 420 and 500 nm occur at the same fluence rates even though these wavelengths correspond to a maximum and a minimum of hemoglobin absorption. These results prove that the hemoglobin cannot be functioning as the visual pigment in phototaxis but, for reasons discussed, they neither confirm nor rule out a role as a shadowing pigment. The results are consistent with a shadowing role in the presence of contrast enhancement by the nervous system.

A steep fluence‐rate dependence suggests that contrast enhancement does occur in Mermis phototaxis. The 420 or 500 nm fluence rate for half‐maximal response is 6 times 10 photons s‐1 cm‐2 (about equivalent in effectiveness to pre‐dawn twilight). The wide range of sensitivity, 350–560 nm, has interesting implications as to the nature of the visual pigment.

†NATO reaearch collaborator a n leave from the Department of Biophysics. Laboratorium voor Algemene Natuurkunde, Rijksuniversiteit Groningen, Westersin‐gel 34. 9718 CM Groningen, The Netherlands.
MECHANISMS FOR LUMINOL‐AUGMENTED CHEMILUMINESCENCE FROM NEUTROPHILS INDUCED BY LEUKOTRIENE B4 AND N‐FORMYL‐METHIONYL‐LEUCYL‐PHENYLALANINE
Authors: GYLLENHAMMAR HANS
Published: January 2008

Abstract Neutrophils stimulated with formyl‐methionyl‐leucyl‐phenylalanine (fMLP) or leukotriene B4 (LTB4) generated kinetically distinctive luminol augmented chemiluminescence (LCL). Inhibitors of O2‐ [superoxide‐dismutase (SOD) or tiron], H2O2 (catalase), myeloperoxidase, MPO, (NaN3), HOCl (taurine) and OH (mannitol) hampered LCL dose‐dependently with similar characteristics for both stimuli. In cell free systems it was found that O2‐ (generated in the xanthine/xanthine‐oxidase reaction) or H2O2 produced LCL. Superoxide dismutase inhibited O2‐‐induced LCL dose dependently. The MPO + H2O2 system, which generated more pronounced LCL than either component alone, was inhibited by catalase and taurine but not by SOD. When neutrophils, treated with luminol, but where extracellular luminol had been removed, were stimulated with fMLP or LTB4, they produced <2% of the LCL where luminol was present in the medium. When neutrophil LCL and superoxide formation by the cytochrome C method were assessed in parallel experiments, in all instances the peak LCL response coincided with the linear phase in that response. Thus, LCL, induced by LTB4 and the corresponding fMLP peak, are extracellular events with similar chemical backgrounds, closely related to generation of reactive oxygen species. Consequently, the kinetical differences in LCL between fMLP and LTB4 suggest that LTB4, by yet unknown mechanisms, activates the NADPH oxidase more rapidly than fMLP.
AN ESR STUDY OF THE VISIBLE LIGHT PHOTOCHEMISTRY OF GILVOCARCIN V
Authors: ALEGRIA ANTONIO E. , KRISHNA C. MURALI , ELESPURU ROSALIE K. , RIESZ PETER
Published: January 2008

Abstract Photolysis of gilvocarcin (GV) at 405 nm in argon saturated dimethylsulfoxide (DMSO) or 50% DMSO‐water solutions in the presence of the sodium salt of 3,5‐dibromo‐2,6‐dideutero‐4‐nitrosobenzene sulfonic acid (DBNBS‐d2) generates the CH3‐DBNBS‐d2 spin adduct. It is postulated that this spin adduct is produced by photoreduction of DMSO by GV and the consequent formation and trapping of the generated methyl radicals. Gilvocarcin V also photoreduces oxygen and methyl viologen with quantum yields of 0.019 and 0.0012 respectively. The quantum yield for singlet oxygen formation by GV in DMSO, determined by measuring the rate of production of the nitroxyl radical produced by the reaction of 2,2,6,6‐tetramethylpiperidinol with singlet oxygen, was found to be 0.15. Thus, GV photochemistry proceeds by both Type I and Type II pathways which could contribute to the reported GV phototoxicity in biological systems.
STUDIES ON THE INTERRELATIONSHIP AMONG THE INTENSITY OF A RAMAN MARKER BAND OF CAROTENOIDS, POLYENE CHAIN STRUCTURE, AND EFFICIENCY OF THE ENERGY TRANSFER FROM CAROTENOIDS TO BACTERIOCHLOROPHYLL IN PHOTOSYNTHETIC BACTERIA
Authors: HAYASHI HIDENORI , NOGUCHI TAKUMI , TASUMI MITSUO
Published: January 2008

AbstractResonance Raman spectroscopy was used to study the polyene‐chain structure of carotenoids in light‐harvesting pigment‐protein complexes from purple photosynthetic bacteria. When major carotenoids ofRhodobacter sphaeroideswere incorporated into the light‐harvesting complexes ofChromatium vinosum, they showed a relatively intense Raman band at 965 cm‐1arising from the CH out‐of‐plane wagging modes of the polyene chain. This result was almost the same as that for the intrinsic carotenoids inChromatium vinosum, but completely different from that for the intrinsic carotenoids inRhodobacter sphaeroides. On the other hand, the intrinsic carotenoids ofChromatium vinosumlost the intensity of the 965 cm‐1Raman band upon protein denaturation. These results support the view that the intensity of the 965 cm‐1Raman band reflects distortion of the polyene chain, independent of its chemical structure. The polyene‐chain distortion is affected by the apoprotein to which carotenoids are bound. The distortion of the polyene chain is correlated with a decrease in the efficiency of the energy transfer from carotenoids to bacteriochlorophyll.
GEOMETRY OF INTERCALATION OF PSORALENS IN DNA APPROACHED BY MOLECULAR MECHANICS*
Authors: Demaret Jean‐Philippe , Brunie Simone , Ballini Jean‐Pierre , Vigny Paul
Published: January 2008

Abstract—

The results of molecular mechanical calculations on intercalation complexes of 3‐car‐bethoxypsoralen, 5‐methoxypsoralen, 8‐methoxypsoralen, 7‐methylpyrido[3,4‐c]psoralen (MepyPs) and 7‐methylpyrido[4,3‐c]psoralen (2N‐MePyPs) with the double stranded duodecanucleotide d(CGCGATATCGCG)2are presented. In the energy‐minimized structures, the psoralens are intercalated with their plane orthogonal to the helix axis. Stacking interactions between the furan ring of the psoralen and the adjacent bases are maximized in most derivatives studied, whereas the effect of the various substituents of the psoralen ring is to specifically push part of the molecule towards either the minor or the major groove, preventing a symmetrical intercalation (with respect to the two strands of the DNA). The relative position of the psoralen ring and of the adjacent thymine foreshadows the formation of furan‐side monoadducts in 3‐CPs, MePyPs and 2N‐MePyPs, whereas the formation of a pyrone‐side monoadduct appears as geometrically more favourable in 5‐MOP and both furan‐ and pyrone‐side monoadducts can be geometrically envisaged in 8‐MOP. A good correlation therefore exists between the more or less favourable equilibrium geometries and the experimentally observed photoreactions. The present study is the first attempt to characterize the geometrical parameters as part of a complex set of geometrical, dynamical and excited state parameters governing the overall DNA‐psoralen photoreaction.
MONOFUNCTIONAL ANGULAR FUROCOUMARINS: SEQUENCE SPECIFICITY IN DNA HOTOBINDING OF 6,4,4′‐TRIMETHYLANGELICIN and OTHER ANGELICINS
Authors: Miolo G. , DallAcqua F. , Moustacchi E. , Sage E.
Published: January 2008

Abstract—

The sequence specificity in the photoreaction (365 nm) of 6,4,4′‐trimethylangelicin (TMA) with DNA fragments of the lac I gene of Escherichia coli was studied by using DNA sequencing methodology. In order to map the sites of TMA photoaddition, we took advantage of the (3′‐5′) exonuclease activity associated with T4 DNA polymerase, which is blocked by bulky adducts, such as furocoumarin photoadducts. A quantitative analysis of the sites of photoaddition is reported. TMA was demonstrated to photoreact with thymine and, to a lower extent, to cytosine. AT‐rich sequences and I'll sites in a GC context are the most reactive sites towards TMA whereas TA, AT, CA, AC sites are weaker sites with similar reactivity. Cytosines in alternated CG sequences are also targets of TMA photobinding. We observed a less pronounced sequence specificity of TMA than that of other psoralen derivatives already studied (Sage and Moustacchi, 1987; Boyer et al., 1988). A comparison with other furocoumarins 4,4′‐dimethylangelicin (4,4′‐DMA), 4′‐methylangelicin (4′‐MA), angelicin, 4,5′,8‐trimethylpsoralen (TMP) and 8‐methoxypsoralen (8‐MOP) is also reported. The role of flanking sequence and consequently of the local conformation at the various sites of photoaddition is discussed. A preferential orientation of the TMA molecule during the intercalation in the dark is suggested. Hot alkali treatment of TMA‐modified DNA did not reveal any DNA strand breakage due to photooxidized bases.
THE EFFECTS OF NEAR‐UV RADIATION ON HUMAN LENS β‐CRYSTALLINS: PROTEIN STRUCTURAL CHANGES and THE PRODUCTION OF O2_ and H2O2
Authors: Andley Usha P. , Clark Barbara A.
Published: January 2008

Abstract—

β‐Crystallins (β1,‐, β2‐ and β3‐crystallin) comprise nearly half the protein of the human lens. The effect of near‐UV radiation, which is one of the possible risk factors in cataract formation, on the p‐crystallins is investigated in this study. Protein intersubunit crosslinking, change in charge of the protein subunits to more acidic species and changes in protein tertiary structure (conformation) by 300 nm irradiation are reported. The fluorescence yield of protein tryptophan residues decreases by 300 nm irradiation. There is an increase in nontryptophan fluorescence (λcx 340 nm, λcm 400–600 nm), and in protein absorption at 340 nm, due to the formation of tryptophan photooxidation products. Both tryptophan and its oxidation products can be photoexcited by 300 nm irradiation and the latter are known to be good photosensitizers. The results provide evidence for the generation of H202 in the irradiated human β‐crystallin solutions by the Type I photosensitizing action of the chromophores absorbing at 300 nm. The H2O2 is generated via the intermediate production of O‐2 anion; the latter spontaneously dismutates to H202, presumably via O ‐2 ‐ protein interactions. The amount of H2O2 generated per absorbed photon is compared for various solutions of β1,‐, β2‐ and β3‐crystallins from human lenses of different age.
PHOTOPROPERTIES OF ALKOXY‐SUBSTITUTED PHTHALOCYANINES WITH DEEP‐RED OPTICAL ABSORBANCE
Authors: Ford W. E. , Rihter B. D. , Kenney M. E. , Rodgers M. A. J.
Published: January 2008

Abstract—

Triplet‐state properties of 1,4,8,11,15,18,22,25‐octa‐n‐butoxy phthalocyanine and its zinc derivative were determined for the first time. The T1 state of the metal‐free phthalocyanine was characterized by a short lifetime (τT= 17 µs) and low quantum yield (φT= 0.095), and quenching of the triplet by O2 occurred with a bimolecular rate constant (kTσ= 1.3 times 108M‐1 s‐1) that is indicative of an endogonic reaction. The zinc complex (ZnPc(OBu)8) was markedly better as a triplet photosensitizer with respect to both tT (60 µs) and φT (0.5). Quenching by O2 produced singlet oxygen with nearly 100% efficiency, and kTσ (1.7 times 109M‐1s‐1) was close to the spin‐statistical diffusion‐controlled limit. Phosphorescence measurements showed the energy of the T1 state of ZnPc(OBu)8 to be 100 kJ/mol, which is 6 kJ/mol above the lδg state of O2. These photoproperties, together with Q‐band absorption maxima in the mid‐700 nm range indicate that metal‐centered 1,4,8,11,15,18,22,25‐octaalkoxyphthalocyanines have excellent potential as sensitizers in photodynamic therapy.
RED EDGE EXCITATION EFFECT IN INTACT EYE LENS
Authors: Rao Ch. Mohan , Rao S. Chenchal , Rao P. Bheema
Published: January 2008

Abstract—

Shift in the wavelength of emission upon shift in the excitation wavelength towards the red edge of the absorption band is termed Red Edge Excitation Shift (REES). This effect is observed only in a situation where the fluorophore mobility with respect to the surrounding matrix is considerably reduced. We have observed such red edge excitation effect in the intact eye lens. The REES observed for a normal lens is different from that seen in a photodamaged lens and hence appears to be a potential tool to monitor the changes in the state of the lens. Photodamage experiments with tryptophan in polyethylene glycol (PEG) and intact eye lens indicate that the red edge photon can also cause photodamage.
OZONE, MIDDLE ULTRAVIOLET RADIATION AND THE AQUATIC ENVIRONMENT
Authors: Smith Raymond C.
Published: January 2008

Marine organisms in the upper layers of the sea may be endangered by increased ultraviolet radiation resulting from declines in the thickness of stratospheric ozone. Evidence supporting this hypothesis includes the fact that wavelengths of potentially damaging ultraviolet radiation can penetrate to ecologically significant depths and laboratory findings that many marine organisms are extremely sensitive to this radiation. Estimated effects of increased ultraviolet radiation on populations of marine organisms range from insignificant to catastrophic. Direct estimation of population effects have not been made, although this is the only adequate measure of the potential impact. The extreme diminution of ozone during the Antarctic spring, coupled with the dynamics of phytoplankton production in this region, may provide conditions suitable for an environmental test of the hypotheses that marine organisms are endangered by reduced stratospheric ozone. There is an urgency to the testing of this hypothesis since these populations may be directly impacted at the present time.
ALL‐trans RETINAL PHOTOISOMERIZATION AND PHOTOOXIDATION FROM UV LASER RADIATION. VIBRATIONAL ASSIGNMENTS OF ALL‐trans 5,8‐PEROXYRETINAL
Authors: BARON M. H. , COULANGE M. J. , COUPRY C. , BARON D. , FAVROT J. , ALY M. M. ABO
Published: January 2008

Abstract— Photoisomerization and photooxygenation of all‐trans retinal in acetonitrile, illuminated by laser radiations (λact, = 333.6 or 350.7 nm), were investigated under various experimental conditions. In deoxygenated solutions, the major photoproducts are 13‐cis and 9‐cis retinal. All‐trans and 13‐cis 5,8‐peroxyretinal are obtained in large amounts in oxygenated solutions. 11‐cis derivatives have not been detected in any of these solutions. The photoproducts were identified by UV, NMR, mass and vibrational spectroscopies and HPLC chromatography. All‐trans and 13‐cis 5,8‐peroxyretinal were isolated. Their vibrational spectra (IR and Raman) are analyzed. Most of the bands are assigned by comparison with previous studies on all‐trans and 13‐cis retinal, (E,E,E)‐3‐methyl‐2,4,6‐octatrienal and peroxides.
THE PEROXIDASE/OXIDASE ACTIVITY OF SOYBEAN LIPOXYGENASE ‐ I. TRIPLET EXCITED CARBONYLS FROM THE REACTION WITH ISOBUTANAL AND THE EFFECT OF GLUTATHIONE
Authors: SCHULTE‐HERBRUGGEN THOMAS , SIES HELMUT
Published: January 2008

Abstract

Soybean lipoxygenase shows a secondary peroxidase/oxidase activity: The aerobic reaction with isobutanal, enhanced by hydrogen peroxide as a cosubstrate, yields acetone, exhibits chemiluminescence and consumes oxygen (φcl= 1.3 × 10‐9photons/O2molecule consumed). 9,10‐Dibromoanthracene‐2‐sulfonate increases the photoemission (kelφ= 2 104M‐1;= 0.9 × 10‐7photons/O2), whereas it is diminished by sorbate, tryptophan, 2‐methyl‐1,4‐naphthoquinone, glutathione, and superoxide dismutase. In the presence of hydrogen peroxide the lipoxygenase reaction with glutathione yields yet another excited state.

From the well‐known reactions promoted by horseradish‐peroxidase, these features are concluded to indicate the novel activity of soybean lipoxygenase. With isobutanal as a substrate lipoxygenase acts as an oxidase and as a peroxidase. The mechanism suggested leads to photoemissive triplet excited acetone as expected from the cleavage of an intermediate dioxetane.
THE PEROXIDASE/OXIDASE ACTIVITY OF SOYBEAN LIPOXYGENASE – II. TRIPLET CARBONYLS AND RED PHOTOEMISSION DURING POLYUNSATURATED FATTY ACID AND GLUTATHIONE OXIDATION
Authors: SCHULTE‐HERBRUGGEN THOMAS , SIES HELMUT
Published: January 2008

Abstract

During the aerobic reaction of soybean lipoxygenase with polyunsaturated fatty acids (linoleic, linolenic, and arachidonic acid) oxygen uptake is followed by excited carbonyl photoemission. The chemiluminescence yield of φcl= 10‐10photons/O2molecule consumed is enhanced 2–3 orders of magnitude by the carbonyl sensitizers 9,10‐dibromo‐anthracene‐2‐sulfonate (kETφ= 104M‐1; φcl= 10‐8photons/O2) and chlorophyll‐a(kETφ= 106M‐1φcl= 10‐7photons/O2), respectively. α,β‐Saturated triplet excited carbonyls as from 1,2‐dioxetane cleavage are discussed to arise from a secondary peroxidase/oxidase reaction with aldehydes formed in the course of enzymic lipid peroxidation.

When 1 mMglutathione is added to the aerobic lipoxygenase/arachidonate reaction, carbonyl emission (375–455 nm) is replaced by intense red bands (630–645 nm and 695–715 nm) resembling the characteristic spectrum of (1†g)O2‐singlet oxygen dimol‐emission. The quantum yield (φcl= 10‐8photons/O2) remains unaffected by chlorophyll indicating that the red emission is independent of excited carbonyls. The effect of GSH is attributed to dioxetane interception and subsequent glutathione peroxidation generating1O2by electron transfer from the superoxide anion radical to a peroxysulfenyl radical.
LIGHT‐CONTROLLED ADAPTATION KINETICS IN Phycomyces: EVIDENCE FOR A NOVEL YELLOW‐LIGHT ABSORBING PIGMENT
Authors: GALLAND PAUL , OREJAS MARGARITA , LIPSON EDWARD D.
Published: January 2008

Abstract— When sporangiophores of the fungus Phycomyces blakesleeanus adapt from high to low fiuence rate, dark adaptation (sensitivity recovery) can be accelerated by dim subliminal light [Galland et al. (1989) Photochem. Photobiol. 49, 485–491]. We measured fiuence rate‐response curves for this acceleration under the following conditions. After sporangiophores were initially adapted symmetrically to a fiuence rate of 1 W m‐2 (447 nm), they were exposed to unilateral subliminal light (subthreshold for phototropism) of variable wavelength and fiuence rate, and then to unilateral test light (447 nm) of fiuence rate either 10‐3 or 10‐5 W m‐2. The duration of the subliminal light was chosen so that phototropism would not occur during this period. Phototropic latencies could be shortened by subliminal light that was less intense than the test light by several orders of magnitude. In experiments with the final unilateral light of fiuence rate 10‐3 W m‐2, the 447 nm subliminal light had a threshold (for the acceleration effect) of about 10‐11 W m‐2. Yellow light of wavelength 575 nm, which itself is extremely ineffective for phototropism was extremely effective in shortening phototropic latencies in response in response to the test light. At 575 nm, the threshold was about 2 × 10‐12 W m‐2. Conversely, near‐UV light of wavelength 347 nm, which is highly effective for phototropism, was relatively ineffective (threshold ‐7 × 10‐8 W m‐2) in shortening the phototropic latency. Our results suggest the presence of a novel yellow‐light absorbing pigment in Phycomyces that specifically regulates dark adaptation. The mutant strain C109 (madB101), which has a defective blue‐light photoreceptor system [Galland and Lipson, (1985), Photochem. Photobiol. 41, 331–335] was also defective for the subliminal effect of blue (447 nm) and yellow (575 nm) light. To interpret these and other results, we suggest that the blue‐light photoreceptor system might include a flavoprotein with photochromic properties. The two interconvertible forms of the photochrome could be the oxidized and semiquinone states of the flavin receptor. The semiquinone state accordingly would control adaptation and mediate the novel yellow‐light effect.
ADENYLATE KINASE BOUND TO THE CHROMATOPHORE MEMBRANES OFRhodobactor spheroidesG1C
Authors: KOYAMA YASUSHI , NAKANO TOMOKO , UTSUMI HIROAKI , YAMAMOTO SHOICHI
Published: January 2008

Abstract—Transformation of adenylates (AMP, ADP and ATP) by washed chromatophore membranes ofRhodobactor spheroidesG1C in the dark and in the light indicated the functions of ATPase (ADP + Pi ← ATP) and of an adenylate kinase (2ADP ← AMP + ATP). The activity of adenylate kinase of the chromatophores was not inhibited by AP5A, and persisted even after sonication in the presence of EDTA or CaCl2; the results suggested the presence of an adenylate kinase bound to the chromatophore membrane. In search of the enzyme, the supernatant after sonication of the chromatophores in the presence of EDTA was subjected to a molecular sieve and then to ion‐exchange HPLC; a fraction with high specific adenylate kinase activity, containing a very sharp peak at 55 kDa, was isolated. Preliminary characterization indicated that it is different from the well‐documented water‐soluble 33 kDa adenylate kinase.
PHOTOCOAGULATION OF HUMAN PLASMA: ACYL SERINE PROTEINASE PHOTOCHEMISTRY
Authors: Porter Ned A. , Bruhnke John D.
Published: January 2008

Abstract— Human a‐thrombin or bovine Factor Xa was acylated at the active site serine hydroxy! with a‐methyl‐2‐hydroxy‐4‐diethylaminocinnamic acid. These modifed serine proteinase enzymes showed no plasma coagulation biological activity in the absence of light. Photolysis of the acyl serine proteinase enzymes in plasma for1–35 s with monochromatic 366 nm light isolated from a high pressure mercury arc results in coagulation of the plasma. For example, photolysis of 3 NIH U of the acyl human a‐thrombin for 5 s in human plasma results in a clot in 23 s. For comparison, 1 NIH U of unmodified human a‐thrombin gave a clot in 21 s under the conditions of the assay but without photolysis. Appropriate controls showed that the coagulation is the result of the formation of active thrombin due to photodeacylation of the enzymes. The photoinduced clotting time measured is dependent on acyl thrombin concentration and photolysis time. Thus higher concentrations of acyl thrombin and longer photolysis times give a shorter clotting time. A kinetic scheme based upon Lineweaver‐Burke analysis of the clotting process is developed.
PHOTOREGULATION OF ROOT: SHOOT RATIO IN SOYBEAN SEEDLINGS*
Authors: Britz Steven J.
Published: January 2008

Abstract— The partitioning of plant growth between shoot and root has the potential to affect diverse physiological processes including water and nutrient uptake, nitrogen fixation, light interception, and interactions between plant and soil microorganisms. Root: shoot ratio is determined both by genetics and developmental status as well as by availability of water, nutrients and light. It is shown here that relative root growth was modulated by photomorphogenetic treatments designed to affect phytochrome (supplemental far‐red radiation given either as an end‐of‐day treatment or continuously during the photoperiod) or blue light photoreceptors (blue light‐deficient low pressure sodium lamps ± low irradiances of supplemental blue [i.e. 5% of total photon flux: 25 μ.mol m−2 s−1]). Photomorphogenetic control of root: shoot ratio was apparent within1–2 days when light treatments were initiated at emergence, and did not necessarily involve changes in net seedling growth. On the other hand, shortened daylength inhibited early seedling growth but had little effect on partitioning. Changes in relative root dry matter induced by supplemental far red radiation or blue light deficiency were similar to those caused by low irradiances, suggesting that phytochrome or blue light photoreceptors may be involved in regulating the partitioning of growth between shoot and root as a part of adaptation to vegetation shade. The influence of spectral quality on root: shoot ratio should be considered when comparing plants grown under different types of lighting or with different spacing.
PHYTOCHROME CONTROL OF EXTRACELLULAR PEROXIDASE ACTIVITY IN MUSTARD INTERNODES: CORRELATION WITH GROWTH, and COMPARISON WITH THE EFFECT OF WOUNDING
Authors: Casal Jorge J. , Whitelam Garry C. , Smith Harry
Published: January 2008

Abstract— The effects of phytochrome status on extracellular peroxidase activity were investigated in Sinapis alba L. seedlings grown for 12 days under continuous white light and transferred to darkness after a red light or a far‐red light pulse. The rates of extension growth and dry matter accumulation in the first internode were increased by the far‐red light pulse. Extracellular proteins, obtained by low speed centrifugation of intact internodes infiltrated with CaCl2, were separated by isoelectrofocusing, and four extracellular acidic peroxidases were resolved, the most active being A3 and A4 (both ˜60 kD). The activity of A4 was reduced by the far‐red light pulse perceived by phytochrome, while the activity of A3 was unaffected. The promotion of internode extension growth caused by far‐red light is biphasic [Casal and Smith (1989) Plant, Cell Environ.12,511–50]. Changes in peroxidase activity were detected prior to the second, but not to the first phase of the internode growth promotion. The effects on both growth and peroxidase activity were virtually restricted to the upper half of the internode and, once established, did not subsequently increase in magnitude.

In contrast to the effects mediated by phytochrome, blue light pretreatments affected growth but not extracellular peroxidase activity. Wounding the internode reduced extension growth, increased the activity of A3, but caused no significant effects on A4.

Other extracellular proteins, separated in sodium dodecyl sulphate polyacrylamide gels and stained with Coomassie blue, showed no significant differences. The concentration of extracellular proteins was higher in the upper than the lower half of the internode.

Results are discussed in terms of phytochrome effects in light grown plants, peroxidase activitv‐arowth relationships, and extracellular peroxidase isoform functions.
PHOTOTROPISM OF THE Phycomyces SPORANGIOPHORE: A COMPARISON WITH HIGHER PLANTS
Authors: Galland Paul
Published: January 2008

Abstract— The basic phenomena of Phycomyces phototropism are described and compared with those of Avena and Zea coleoptiles and the seedlings of Arabidopsis, Cucumis, Helianthus, Raphanus and Sesamum. Symmetric redistribution of growth rate during curvature, a feature characteristic of Phycomyces phototropism, can in some cases also be found in plants. Common features are: complex fiuence‐response curves, log‐linear fluence dependence of the phototropic latency, relatively slow bi‐exponential dark‐adaptation and fast light‐adaptation kinetics, action spectra indicating the ubiquitous flavin‐like photoreceptor(s) as well as other non‐flavin receptors, and spacial memory as indicated by phototropic reversal experiments. The problem how phototropic curvature is maintained continuously while the light‐growth response adapts, remains unexplained (“phototropism paradox”). For Phycomyces it is shown that some of the most basic information processes, which include contrast recognition, wavelength sensitivity and sensitivity recovery (sensor adaptation) are mediated by the photoreceptor systems.
IONIC STRENGTH EFFECTS ON THE GROUND STATE COMPLEXATION and TRIPLET STATE ELECTRON TRANSFER REACTION BETWEEN ROSE BENGAL and METHYL VIOLOGEN
Authors: Douglas P. , Waechter G. , Mills A.
Published: January 2008

Abstract— The equilibrium constants, Kc, for complexation between methyl viologen dication (MV2+) and Rose Bengal, or Eosin Y, decrease with increasing ionic strength. At zero ionic strength Kc is 6500 (± 500) mol−1 dm3 for Rose Bengal and 3200 (± 200) mol−1 dm3 for Eosin Y, and these values decrease to 1500 (± 100) and 680 (± 40) mol−1 dm3, respectively, at an ionic strength of 0.1 mol dm−3. Kc is independent of pH between 4.5 and 10. ΔH is ‐25 (± 1) kJ mol−1 for complexation with either dye, whereas ΔS is ‐15 (± 3) J K−1 mol−1 for Rose Bengal, and ‐ 23 (± 3) J K−1 mol−1 for Eosin Y. The complexation constant for Rose Bengal and the neutral viologen, 4,4'‐bipyridinium‐N, N'‐di(propylsulphonate), (4,4'‐BPS), is 420 (± 35) mol−1 dm3, and independent of ionic strength. No complexation could be observed for either Rose Bengal or Eosin with another neutral viologen, 2,2'‐bipyridinium‐N,N'‐di(propylsulphonate), (2,2'‐BPS). MV2+ quenches the triplet state of Rose Bengal with a rate constant of 7 × 109 mol−1 dm3 s−1, and this rate constant decreases slightly as ionic strength increases. The cage escape yield following quenching, Φcc is very low (Φcc= 0.02 (± 0.005), and independent of ionic strength. 4,4'‐BPS quenches the triplet state of Rose Bengal with a rate constant of 2.2 (± 0.1) × 109 mol−1 dm3 s−1, and gives a cage escape yield of 0.033 (± 0.006). 2,2'‐BPS quenches the Rose Bengal triplet with a rate constant of 6 (± 1) × 108 mol−1 dm3 s−1 and gives a cage escape yield of 0.07 (± 0.01). Conductivity measurements indicate that MV2+(Cl−)2 is completely dissociated at concentrations below 2 × 10−2 mol dm−3.
INTRACELLULAR LOCALIZATION OF SULFONATED meso‐TETRAPHENYLPORPHINES IN A HUMAN CARCINOMA CELL LINE*
Authors: Berg Kristian , Western André , Bommer Jerry C. , Moan Johan
Published: January 2008

Abstract—The intracellular localization of meso‐tetraphenylporphines sulfonated to different degrees (TPPSn), in a human cervix carcinoma cell line (NHIK 3025), was studied by fluorescence microscopy and fluorescence spectroscopy. After an 18 h incubation, TPPS4, TPPS2aand TPPS2owere localized in extranuclear granules. Studies of cells stained with both TPPS4and acridine orange, which is known to fluoresce red in lysosomes, indicated that these granules were lysosomes. In addition, a fraction of the cellbound TPPS4, TPPS2aand TPPS2oseems to be associated with the plasma membrane. Fluorescence quenching studies of cells doublestained with acridine orange and TPPS4indicated that TPPS4is also localized in the nucleus and in the extralysosomal cytoplasm. The intracellular location of TPPS, differed from that of the other TPPSns studied: In 6 out of 9 experiments fluorescing extranuclear granules were found. A diffuse fluorescence extending from the perinuclear area was also observed.
POST‐TREATMENT INTERACTIONS OF PHOTODYNAMIC and RADIATION‐INDUCED CYTOTOXIC LESIONS
Authors: Ramakrishnan Narayani , Clay Marian E. , Friedman Libby R. , Antunez Antonio R. , Oleinick Nancy L.
Published: January 2008

Abstract— The interaction of chloroaluminum phthalocyanine‐sensitized photodynamic treatment and γ‐irradiation was studied in confluent murine L929 fibroblasts. When the cells were given the combined treatments and immediately subcultured for determination of cell survival by colony formation, the data indicate independent actions of each modality. However, when subculture was delayed for 1 h, a substantial fraction of cells treated with a sub‐lethal dose of PDT followed by 5 Gy γ‐radiation detached from the monolayer. Most of these detached cells were no longer clonogenic. The mode of photosensitized cell killing was found to be different from that of ionizing radiation‐induced cell killing. Photosensitized cell killing was accompanied by morphological changes in the cells and extensive DNA degradation within one hour following the treatment. When chloroaluminum phthalocyanine pre‐treated cells were exposed to a sublethal fluence of light (6 kJ/m2) and a lethal dose of γ‐radiation (5 Gy), DNA degradation was enhanced, and about 20% of the cell population appeared to undergo the type of cell death typical of photodynamic treatment. Thus, although different initial lethal lesions are induced by photodynamic treatment and by ionizing radiation, interactions may occur during processing of the damage.
EFFECT OF OXYGEN ON PHOTO AUTOTROPHIC and HETEROTROPHIC GROWTH OF Chlamydomonas reinhardtii IN AN ANOXIC ATMOSPHERE
Authors: Graves Duane A. , Spradlin Ginger M. , Greenbaum Elias
Published: January 2008

Abstract—Photoautotrophic growth ofChlamydomonas reinhardtiiwas shown to be independent of the presence of atmospheric oxygen. Under constant light and photoautotrophic conditions, C.reinhardtiigrew equally well in either air or 367 PPM C02‐in‐He. During 12‐h light‐dark cycles, the cells in air grew substantially faster than those grown in C02‐in‐He, indicating a significant role for 02in dark metabolism. Although cells grown under C02‐in‐He were not supplied any exogenous 02, photosynthetic water splitting resulted in the liberation of 02. The effect of photoevolved 02on the growth ofC. reinhardtiiwas examined (1) by measuring the amount of 02consumed by photosynthesiz‐ing algae, (2) by growing the algae heterotrophically on acetate in the dark and supplied with 02generated by photoautotrophically grown cells, and (3) by determining the minimum level of 02needed to stimulate C02evolution from cells suspended in minimal medium supplemented with acetate. The results from these investigations indicated that exogenous 02was not required for photoautotrophic growth byC. reinhardtiiand that this alga grew in an anoxic environment if supplied with C02and light.
ON THE MULTIPLE CYCLES OF BACTERIORHODOPSIN AT HIGH pH
Authors: Bitting Herbert C. , Jang Du‐Jeon , El‐Sayed M. A.
Published: January 2008

Bacteriorhodopsin (bR) shows at least two parallel photocycles at pH 10.5, suggesting that more than one form of bR exists in alkaline bR sample. Upon the absorption of visible light, the different forms of bR at high pH yield different parallel intermediates: M412 with two rise and two decay components; and R, an extremely fast rising and extremely slow decaying intermediate with an absorption peak at 350 nm. The kinetics and spectra do not agree with the proposal of Kouyama el al. (1988, Biochemistry 27,5855–5863) that the 350 nm‐absorbing species is the N intermediate which follows M412 and that the slow decaying M412 is an M‐like photoproduct of N. Our results basically agree with the proposal of Dacshazy et al. (1988, Proc. Natl. Acad. Sci. USA 85,6358–6361) that the fast and slow decaying M412 intermediates and R are in independent photocycles arising from different forms of bR. The different forms of bR are probably in dynamic equilibrium with their ratios controlled by pH and ionic strength.
QUINONES AS MEDIATORS OF ELECTRON TRANSFER FROM MEMBRANE‐BOUND CHLOROPHYLL TO CYTOCHROME c IN THE AQUEOUS PHASE IN LIPID BILAYER VESICLES: SYNERGISTIC ENHANCEMENT OF CYTOCHROME c REDUCTION BY LIPOPHILIC/ HYDROPHILIC QUINONE PAIRS
Authors: Chamupathi V. G. , Tollin G.
Published: January 2008

Laser flash photolysis has been used to determine the kinetics of cytochrome c reduction by chlorophyll triplet state in negatively‐charged lipid bilayer vesicles, as mediated by quinones. Large synergistic enhancements in the yield of reduced cytochrome were obtained using a pair of quinones, one of which was lipophilic (e.g. benzoquinone, 2,6‐di‐f‐butylbenzoquinone) and the other of which was hydrophilic (e.g. l,2‐naphthoquinone‐4‐sulfonate). The mechanism was shown to involve initial quenching of the triplet by the membrane‐associated quinone to form chlorophyll cation radical and quinone anion radical. An interquinone electron transfer process followed this reaction, which occurred at the membrane‐water interface, and greatly facilitated electron transport from within the bilayer to the aqueous phase. This process formed the basis of the synergistic effect. Cytochrome c reduction occurred in the water phase by reaction with the anion radical of the hydrophilic quinone. Finally, the reduced cytochrome was reoxidized by a slow reaction with chlorophyll cation radical. Under the most favorable conditions, we estimate that the quantum yield of conversion of triplet quenching events to reduction of cytochrome approached unity. The lifetime of the reduced protein and oxidized chlorophyll could be as long as 140 ms, under the best conditions. This system has properties which are thus quite favorable for solar energy conversion in a biomimetic process.
EFFECT OF TEMPERATURE AND pH ON THE QUENCHING OF TRIPLET LUMIFLAVIN IN THE PRESENCE AND ABSENCE OF FERRI‐ AND FERROCYANIDE
Authors: Naman S. A.
Published: January 2008

Abstract—–Flash photolysis at 450 nm over the temperature range 0.8–60°C was used to determine Arrhenius parameters for the first and second order disappearance of triplet lumiflavin (1.66 µ.M) at a flash energy of 2 kj in deaerated phosphate buffer at varying pH:

3Lf → Lf0

3Lf +3Lf → Lf0+ Lf0

Arrhenius parameters were also determined for the pseudo first‐order quenching of triplet lumiflavin by 10 µMferri‐ and ferrocyanide ions,

3Lf + Fe3+→ Fe3+→ Lf0+ Fe3+(energy transfer)

3Lf + Fe2+→ Lf‐+ Fe3+(electron transfer)

and for disappearance of the semireduced lumiflavin in the presence of ferrocyanide at pH 6.8, by the second‐order reaction

Lf‐+Lf‐→ Lf0+ Lf=.
EPR STUDIES OF TRAPPED SINGLET OXYGEN (lO2) GENERATED DURING PHOTOIRRADIATION OF HYPOCRELLIN A
Authors: Zang Lun‐Yi , Zhang Zhiyi , Misra Hara P.
Published: January 2008

Abstract— Hypocrellin A, a peryloquinone derivative, has recently been isolated from the sacs of the fungus Hypocrella bambusae. This pigment, in combination with phototherapy, has been used in human medicine to cure various skin diseases. The generation of singlet oxygen during photoirradiation of Hypocrellin A (HA) was detected as an oxidation product of a sterically hindered amine (tetramethylpiperidine oxide; TEMPO) by electron paramagnetic resonance (EPR) spectroscopic techniques. Azide inhibited the EPR signal intensity in a dose‐dependent manner with a quenching rate constant of 3.86 × 108M‐1s‐1 in ethanol. Deuterated solvents, known to increase the lifetime of singlet oxygen, augmented the EPR signal intensity. The rate of production of singlet oxygen was dependent not only upon the concentration of HA and the time of irradiation but also on the oxygen content of the reaction mixture. The hyperfine splitting constant (aN= 16.3 G) and g‐value (g= 2.0056) of the photoproduct of TEMP‐singlet oxygen and TEMPO were found to be identical. This indicates that the nitroxide species detected by EPR spectroscopy generated by reacting TEMP with photogenerated 1O2 is TEMPO. The rate constant (kT) for the reaction of singlet oxygen with TEMP to form TEMPO radical was found to be 5.3 × 105M‐1s‐1.
IS RHODAMINE 123 A PHOTOSENSITIZER?
Authors: Morlière P. , Santus R. , Bazin M. , Kohen E. , Carillet V. , Bon F. , Rainasse J. , Dubertret L.
Published: January 2008

Abstract—–Because of conflicting reports on the phototoxicity of rhodamine 123 (Rh 123), we have undertaken a study of Rh 123 photosensitization in severalin vitrosystems. First, Rh 123 is not a photodynamic agent and does not react with singlet oxygen. Second, when bound to cytochrome c (Cyt c), Rh 123 photosensitizes ferro Cyt c but not ferri Cytcdegradation by an oxygen‐independent process. When delivered to skin fibroblasts where it specifically stains mitochondria, Rh 123 photosensitizes membrane damage. These results are consistent with the hypothesis that Rh 123 is a phototoxic stain. The lack of photosensitivity of Rh 123‐stained mitochondria in some cell lines might therefore be due to specific structural features.
COMPARATIVE KINETICS OF HEMATOPORPHYRIN DERIVATIVE UPTAKE AND SUSCEPTIBILITY OF Bacillus subtilis AND Streptococcus faecalis TO PHOTODYNAMIC ACTION
Authors: Shawar Ribhi , Cooper B. H.
Published: January 2008

Abstract—Hematoporphyrin derivative (HpD) is widely used in photoradiation therapy of tumors and other diseases, and has been shown to affect the viability of gram positive bacteria. This investigation assessed the efficiency of binding of HpD toBacillus subtilisandStreptococcus faecaliswhen HpD‐treated organisms were exposed to red light. Kinetic studies indicated that the amount of HpD bound increased with increasing external concentration of HpD until saturation of binding sites was reached.S. faecalishad a higher affinity for HpD and was more susceptible to photoinactivation thanB. subtilis.The data from this study suggest that differences in susceptibility of microorganisms to photoinactivation are directly related to the affinity of each strain for HpD.
PHOTOOXYGENATION OF BIPHENYL AND ITS DERIVATIVES via PHOTOINDUCED ELECTRON TRANSFER: EFFECT OF Mg(CIO4)2 ON PHOTOOXYGENATION
Authors: Tamai Toshiyuki , Mizuno Kazuhiko , Hashida Isao , Otsuji Yoshio
Published: January 2008

The 9,10‐dicyanoanthracene (DCA)‐sensitized photooxygenation of biphenyl derivatives in the presence of Mg(CIO4)2 in acetonitrile produces benzoic acid and its derivatives in high yields. In the absence of Mg(CIO4)2, the rates for the consumption of biphenyl derivatives decrease by a factor of 0.5‐0.8, compared with those in the presence of Mg(CIO4)2. In these cases, however, both biphenyls and DCA are oxygenated to give benzoic acids and anthraquinone, respectively, indicating that the addition of Mg(CIO4)2 retards the photooxygenation of DCA. With 4‐methylbiphenyl, the photooxygenation proceeds efficiently without added Mg(CIO4)2, and benzene rings and methyl groups are competitively oxygenated to give benzoic acid, 4‐methylbenzoic acid, 4‐phenylbenzoic acid, and 4‐phenylbenzaldehyde. The addition of Mg(CIO4)2 facilitates the oxidation of benzene rings, giving benzoic acid and 4‐methylbenzoic acid as major products. These photooxygenations are initiated by a one‐electron transfer from biphenyls to the excited singlet DCA and proceed via the radical cations of biphenyls and the radical anion of DCA.
SPECTROSCOPIC STUDIES OF CUTANEOUS PHOTOSENSITIZING AGENTS–XVI. ISPERSE BLUE 35
Authors: Dabestani Reza , Reszka Krzysztof J. , Davis Donald G. , Sik Robert H. , Chignell Colin F.
Published: January 2008

The photochemistry (Type I and II) of the phototoxic textile dye Disperse Blue 35 (DB‐35) and its purified components has been studied using electron spin resonance in conjunction with spin trapping technique and the direct detection of singlet oxygen (1O2) luminescence. The main components of DB‐35 (which is synthesized by the successive nitration, reduction and methylation of 1,8‐dihydroxy‐anthraquinone) were separated by HPLC and identified by mass spectrometry and 2‐D NMR as 4,5‐diamino‐1,8‐dihydroxyanthraquinone (4,5‐DDHAQ; 62% of total dye) and 2,7‐diamino‐1,8‐dihydroxyanthraquinone (2,7‐DDHAQ; 31% of total dye). Minor components included 2,5‐diamino‐1,8‐dihydroxyanthraquinone (2,5‐DDHAQ) and a monomethylated derivative of either 4,5‐DDHAQ or 2,7‐DDHAQ. Irradiation (624 nm) of 4,5‐DDHAQ and 2,7‐DDHAQ in dimethylsulfoxide resulted in the generation of superoxide which was trapped by 5,5‐dimethyl‐l‐pyrroline‐N‐oxide (DMPO). Visible light irradiation of the components in ethanol generated 1O2 with the yields decreasing in the following order: 4,5‐DDHAQ > 2,5‐DDHAQ > 2,7‐DDHAQ. These findings indicate that upon irradiation by visible light DB‐35 can generate active oxygen species which may be responsible for the photocontact dermatitis caused by this dye.
THE S0AND Ti STATES OF ISOMERIC CANTHAXANTHIN AS COMPARED WITH THOSE OF β‐CAROTENE: EFFECT OF THE TERMINAL CARBONYL GROUPS DETECTED BY RAMAN SPECTROSCOPY
Authors: Hashimoto Hideki , Koyama Yasushi
Published: January 2008

The S0(ground singlet‐state) Raman spectra of theall‐trans, 9‐cis, 13‐cis, 9,9‐cis, 9, 13‐cis,9,13′‐cisand13,13′‐cisisomers of canthaxanthin as well as the T1(lowest‐excited triplet‐state) Raman spectra of theall‐trans, 9‐cis,13‐cis and 9,13‐cis isomers were recorded. In order to reveal the effect of the carbonyl groups at both ends on the carbon‐carbon conjugated system in‐between (in both the S0and T, states), the carbon‐carbon stretching frequencies were compared between isomeric canthaxanthin and p‐carotene: in the S0state, the C=C stretching frequencies of canthaxanthin were lower by3–10 cm−1than those of β‐carotene, indicating increased conjugation in the former. In the T, state, the “C=C” stretching frequencies of canthaxanthin were lower by12–15 cm−1, indicating a large decrease in the “C=C” bond order in the central part of canthaxanthin. Further, the relations of the C=C (S0) and “C=C” (T1) stretching frequenciesvsthe number of carbon‐carbon double‐bonds were examined for the above two and additional five carotenoids. The result indicated that the terminal carbonyl groups of canthaxanthin are incorporated in the carbon‐carbon conjugated system in the T, state, but that they are almost independent of it in the S0state. Both observations support the idea that the “triplet‐excited region” of canthaxanthin is extended over the entire double‐bond system.
FORMATION OF SINGLE AND DOUBLE STRAND BREAKS IN DNA ULTRAVIOLET IRRADIATED AT HIGH INTENSITY
Authors: Masnyk Taras W. , Minton Kenneth W.
Published: January 2008

The induction of single‐strand breaks (SSB) by two quantum processes in DNA is well established. We now report that biphotonic processes result in double‐strand breaks (DSB) as well. pUC19 and bacteriophage M13 RF DNA were irradiated using an excimer laser (248 nm) at intensities of 107, 109, 1010and 1011W/m2and doses up to 30 kJ/m2. The proportion of DNA as supercoil, open circular, linear and short fragments was determined by gel electrophoresis. Linear molecules were noted at fluences where supercoiled DNA was still present. The random occurrence of independent SSB in proximity to each other on opposite strands (producing linear DNA) implies introduction of numerous SSB per molecule in the sample. If so, supercoiled DNA that has sustainednoSSB should not be observed.

A model accounting for the amounts of supercoiled, open circular, linear and shorter fragments of DNA due to SSB, DSB and Scissions (opposition of two independently occurring SSB producing an apparent DSB) was developed, our experimental data and those of others were fit to the model, and quantum yields determined for SSB and DSB formation at each intensity. Results showed that high intensity laser radiation caused an increase in the quantum yields for both SSB and DSB formation. The mechanism of DSB formation is unknown, and may be due to simultaneous cleavage of both strands in one biphotonic event or thebiasedintroduction of an SSB opposite a preexisting SSB, requiring two biphotonic events.
HOLE‐BURNING SPECTROSCOPY OF ACTIVE AND INACTIVATEE) PHOTOSYSTEM II PARTICLES
Authors: Vacha M. , Adamec F. , Ambroz M. , Baumruk V. , Dian J. , Nedbal L. , Hala J.
Published: January 2008

This paper reports transient and persistent hole‐burning of photosynthetically active as well as chemically reduced and heat inactivated photosystem II particles isolated from cyanobacteria. Transient spectra of active and non‐active particles are significantly different. For both, the possible origin of the bottle‐neck state is discussed. Persistent holes were ascribed to the antenna complex of photosystem II. From their width the energy transfer rate was estimated to be 4.8 ps at 4.2 K.