bluuebunny/crossref_metadata_2025_split huggingface dataset:
ROSEOFLAVIN INHIBITION OF PHOTOCONIDIATION IN A Trichoderma RIBOFLAVIN AUXOTROPH: INDIRECT EVIDENCE FOR FLAVIN REQUIREMENT for PHOTOREACTIONS
Authors: Horwitz Benjamin A. , Malkin Shmuel , Gressel Jonathan 
Published: January 2008

AbstractRoseoflavin, an analog known to compete with riboflavin in Lactobacillus casei, riboflavin‐deficient rats, and fungi, was used to ascertain whether a flavin plays a role as a sensitizing pigment for photomorphogenesis in the fungus Trichoderma. Roseoflavin inhibited blue light induced conidiation of a riboflavin‐requiring auxotroph of Trichoderma. Colonies pre‐incubated with roseoflavin needed six times more light to saturate conidiation. Roseoflavin did not change the dark rate of conidial development indicating that it interfered only with the photoact. A revertant from the riboflavin auxotroph strain was not inhibited by roseoflavin. Simultaneous addition of 10 μM riboflavin prevented inhibition by 6.4 μM roseoflavin. Thus, roseoflavin inhibition is probably specific, possibly replacing riboflavin or one of its metabolites in the light reactions. There was no detectable shift in the action spectrum towards the green where roseoflavin absorbs; thus it did not replace a flavin as an efficient photoreceptor.
FLUORESCENCE OF HOUSEFLY VISUAL PIGMENT
Authors: Stavenga D. G. , Franceschini N. , Kirschfeld K. 
Published: January 2008

Abstract —The fluorescence of housefly photoreceptors was studied in vivo by using the deep pseudopupil technique. Whereas the rhodopsin R490 of the peripheral retinular cells fluoresces negligibly the metarhodopsin M580 fluoresces distinctly in the red. The newly discovered metarhodopsin M’is produced by intense blue light and can be reconverted into rhodopsin by intense long wavelength light. M’also fluoresces in the red; its excitation spectrum and emission spectrum peak at max= 570 and 660 nm respectively.Intense ultraviolet light irreversibly reduces the visual pigment fluorescence as well as the broad band autofluorescence (kmnx 470 nm) originating from non‐visual pigments in the fly's eye.
THE INDUCTION OF ERYTHEMA, EDEMA, and THE POLY AMINE SYNTHESIS ENZYMES ORNITHINE DECARBOXYLASE and S‐ADENOSYL‐L‐METHIONINE DECARBOXYLASE IN HAIRLESS MOUSE SKIN BY PSORALENS and LONGWAVE ULTRAVIOLET LIGHT
Authors: Connor Michael J. , Lowe Nicholas J. 
Published: January 2008

Abstract— The cutaneous toxicities of the furocoumarins 8‐methoxypsoralen (8‐MOP), 5‐methoxypsoralen (5‐MOP), 3‐carbethoxypsoralen (3‐CP), and 5‐methylisopsoralen (5‐MI) administered topically (2 or 4 mg) or orally (25 mg/kg) followed by irradiation with longwave ultraviolet light (UVA) (50 kJ/ m) were compared in hairless mice. Parameters measured were the induction of ornithine decarboxylase (ODC) activity, a potential marker for skin‐carcinogens, S‐adenosyl‐L‐methionine decarboxylase, (SAMDC) activity, and the induction of skin edema (increase in dorsal skin fold thickness) and erythema, both indicators of acute phototoxicity.Edema and erythema, and epidermal ODC activity were induced by topical and oral 5‐MOP, 8‐MOP and 5‐MI when given with UVA. The erythema found after topical 5‐MI + UVA was less than after 8‐MOP + UVA or 5‐MOP + UVA. and first occurred at 48 h. Edema and epidermal ODC activity were also induced at later times, being maximal at 48 h or more. 3‐Carbethoxypsoralen given orally (25 mg/kg) or topically (4 mg) with UVA did not have a consistent effect on the parameters measured, and appeared to be non‐toxic under these conditions.These results of these studies suggest that the low toxicity of 3‐CP + UVA is not necessarily related to its ability to form only monoadducts with DNA. The ability to crosslink with DNA is not a prerequisite for ODC induction and the induction of skin edema since 5‐MI, which can only form monoadducts with DNA, gave a similar response to 8‐MOP and 5‐MOP.
REMOVAL OF PYRIMIDINE DIMERS IN UV‐IRRADIATED SPORES OF Dictyostelium discoideum DURING GERMINATION
Authors: Okaichi Kumio , Tano Keizo , Ohnishi Takeo , Nozu Keiichi 
Published: January 2008

Abstract—The spores of Dictyostelium discoideum TW‐8 (radC) are about twice as sensitive to UV than the parental strain NC‐4 spores at a 10% survival level. Ultraviolet irradiation apparently suppressed the emergence of amoebae from swollen TW‐8 spores as compared with NC‐4 spores, though the conversion of spores into swollen spores was not affected by UV irradiation in either strain. About 85% removal of pyrimidine dimers was detected in UV‐irradiated NC‐4 spores at 200 J/m2 during spore germination for 9 h, but no removal of pyrimidine dimers was detected in TW‐8 spores under the same conditions. The removal of pyrimidine dimers from the NC‐4 spores began at around 2 h germination when the spores have become swollen. The number of enzyme‐sensitive sites (ESS) detected by Micrococcus luteus endonuclease in the DNA of UV‐irradiated NC‐4 spores also began to decrease at about 2 h into germination. The decrease in ESS, however, was hardly detectable in UV‐irradiated TW‐8 spores at any step during germination.Cycloheximide inhibited both decrease in the number of pyrimidine dimers, and decrease in the number of ESS of UV‐irradiated NC‐4 spores. It is suggested that UV‐specific endonuclease is newly synthesized in swollen spores of NC‐4.
DRUG SENSITIZATION: PHOTOBINDING OF SULFANILAMIDE TO BOVINE SERUM ALBUMIN
Authors: Bec Jean Louis , Delrieu Pascal , Abravanel Gérard , Paillous Nicole 
Published: January 2008

Abstract— Photobinding of sulfanilamide to bovine serum albumin (BSA) was investigated by irradiating BSA and buffered BSA/drug solutions with UV light (Λ= 300 nm) under anaerobic conditions. The protein solutions were then denatured and the unbound sulfanilamide removed. Marked differences in the UV and fluorescence spectra of the solutions before and after irradiation were observed, suggesting covalent binding of the drug to BSA. This was confirmed using [14C]labelled sulfanilamide. The extent of photobinding of sulfanilamide determined using the radiolabeled drug, was concentration dependent. The binding ratio varied from 3 mol drug per mol BSA for a 10‐4M drug concentration, to 10 mol drug per mol BSA for 10‐2M drug concentration.The protein solutions were hydrolysed under acid conditions and the amino acids obtained were analysed by ion exchange chromatography. The hydrolysate of irradiated BSA (10‐4M) ‐sulfanilamide (10‐2M) mixture lost about 10 mol of cystine per mol of BSA. This loss was not observed after hydrolysis of irradiated alone or non‐irradiated BSA. Irradiation of cystine with [14C]sulfanilamide in HC1 solutions produced the same compound as was found after hydrolysis of irradiated BSA/sulfanilamide mixtures. This was demonstrated by autoradiography of paper chromatograms. The same compound was also detected in an irradiated [35S]cystine non‐labelled sulfanilamide mixture. It was not detected, however, after irradiation of a mixture of all amino acids of BSA excluding cystine. These data suggest that cystine residues are involved in the photobinding of sulfanilamide (or its photoproducts) to BSA.
VACUUM ULTRAVIOLET NATURAL AND MAGNETIC CIRCULAR DICHROISM WITH CONVENTIONAL SOURCES AND SYNCHROTRON RADIATION
Authors: Snyder Patricia Ann 
Published: January 2008

AbstractVacuum ultraviolet natural and magnetic circular dichroism measurements have added significantly to our knowledge of the geometric and electronic structure of molecules and have provided a better understanding of the correct approach for theoretical calculations. In this review, I define natural and magnetic circular dichroism, and discuss information obtained with these techniques. The instrumentation for vacuum ultraviolet natural and magnetic circular dichroism is reviewed, from its beginning with conventional sources to the present time use of synchrotron radiation. The future possibilities and challenges for these measurements are examined with particular reference to making measurements to higher energies.
WAVELENGTH DEPENDENCE FOR THE INACTIVATION OF ATP IN THE VACUUM‐ULTRAVIOLET REGION ABOVE 140 nm
Authors: Ito Atsushi , Taniguchi Taketoshi , Ito Takashi 
Published: January 2008

AbstractRadiation effects were investigated on the activity and the structure of adenosine triphosphate in the wavelength range from 140 nm to 260 nm, using monochromatized synchrotron radiation from the INS‐SOR storage ring. The sample was irradiated as a thin film in vacuum. The activity of adenosine triphosphate decreased sharply below 180 nm as judged by the luminescence in the luciferin‐luciferase assay. From the exponential decay of function, the cross‐section for inactivation was calculated to be of the order of 10‐21 m2/photon in the range from 140 to 170 nm. No decrease was detected at wavelengths of 190 nm and above. The calculated quantum yield increased as the wavelength became shorter and reached to 0.20 at 150 nm. The release of adenine at 160 nm‐irradiation was detected by thin layer chromatography; no adenosine diphosphate or adenosine monophosphate occurred. Only a trace of adenine was found after 190 nm‐irradiation. These results indicate that the broad absorption peak for higher excitations attributable to the base moiety around 190 nm does not cause both structural and functional changes, while the absorption by the sugar‐phosphate group produces the rupture of N‐glycosidic bond, and probably leads to the loss of function.
PHOTOACOUSTIC SPECTRA OF SOME BIOLOGICAL MOLECULES BETWEEN 300 AND 130 nm
Authors: Inagaki Takashi , Ito Atsushi , Hieda Kotaro , Ito Takashi 
Published: January 2008

AbstractPhotoacoustic spectra of the biological molecules thymine, adenine, tyrosine, ergosterol and polyadenylic acid were obtained in the 300‐130 nm region of photon wavelength using synchrotron radiation as a light source. Photoacoustic measurements were performed with thin solid films of these molecules made by vacuum evaporation, except for polyadenylic acid whose thin films were made from the aqueous solution. It was found that the spectra exhibit absorption structures which are in good agreements with those found from conventional transmission measurements. Some of the spectra, however, exhibit a marked deviation from the transmission data in the region below 145 nm, which may be indicative of photon absorption with subsequent photoelectron emission.
VIRUS‐CELL INTERACTIONS AS PROBES FOR VACUUM‐ULTRAVIOLET RADIATION DAMAGE AND REPAIR
Authors: Coohill Thomas P. 
Published: January 2008

AbstractIrradiation of biological materials in the vacuum‐ultraviolet (VUV*‐wavelengths below 200nm) is inhibited by the substantial absorption of water, air, and of the material itself. We have made a rough estimate of the penetration of radiation to the center of three kinds of cells and three viruses of different sizes at three wavelengths in the VUV (155 nm, 170 nm, and 200 nm) and two wavelengths in the far‐UV (220 nm and 250 nm). With the exception of bacteria, absorption limits the penetration of wavelengths below 200 nm to the center of the cell, to less than one percent of the radiation striking the cell surface. Thus, effects on the genetic material when cells larger than bacteria are irradiated with VUV should be insignificant. However, even the largest viruses were relatively transparent to all the wavelengths that we used. Therefore viruses can be considered to be model organisms for VUV studies; we list some of the maj or advantages of using them as probes to study cellular responses to VUV biological damage. The use of viral probes to study membrane phenomena also is noted since damage by VUV often is limited to cell surfaces. We suggest that the use of viruses may make possible biological experiments in the VUV that were not feasible with cells alone.
LINKED‐FUNCTION ANALYSIS OF FLUORESCENCE DECAY KINETICS: RESOLUTION OF SIDE‐CHAIN ROTAMER POPULATIONS OF A SINGLE AROMATIC AMINO ACID IN SMALL POLYPEPTIDES
Authors: Alexander Ross J. B. , Laws William R. , Sutherland John Clark , Buku Angeliki , Katsoyannis Panayotis G. , Schwartz Irving L. , Wyssbrod Herman R. 
Published: January 2008

AbstractA linked‐function approach to fluorescence decay data analysis is presented that permits complex systems to be resolved from a single decay curve. The method involves linking fluorescence decay parameters based on a relationship established by independent physical measurements. As an example, by correlating the fluorescence data with 1H‐NMR results, the complex fluorescence decay kinetics of tyrosine analogs and single tyrosyl residues in simple polypeptides can be explained by ground‐state rotameric populations of the phenol ring about the Cα‐Cβ bond.
ACTION SPECTRA FOR IN ACTIVATION AND MEMBRANE DAMAGE OF Saccharomyces cerevisiae CELLS IRRADIATED IN VACUUM BY MONOCHROMATIC SYNCHROTRON UV RADIATION (155‐250 nm)
Authors: Hidea Kotaro , Ito Takashi 
Published: January 2008

AbstractWe investigated the wavelength dependence of inactivation and membrane damage in yeast cells (Saccharomyces cerevisiae) in the range from 170 to 200 nm. Action spectra constructed at wavelengths from 155 to 250 nm using published data were nearly the same for the two types of effects below 200 nm, but differed from the absorption spectrum of DNA, indicating that major lethal damage occurred in the membrane, not in DNA. This conclusion was strongly supported by the finding that far‐UV‐sensitive cells, which lack excision repair, showed no enhanced sensitivity below 200 nm.
ANTIVIRAL ACTIVITY OF THE PHOTOACTIVE THIOPHENE α‐TERTHIENYL
Authors: Hudson J. B. , Graham E. A. , Micki N. , Hudson L. , Towers G. H. N. 
Published: January 2008

AbstractThe naturally occurring thiophene, α‐terthienyl, was investigated for phototoxicity against several viruses and a line of mouse cells. The compound was extremely phototoxic to the two‐membrane‐containing animal viruses, murine cytomegalovirus (MCMV) and Sindbis virus (SV). Antiviral activity was detected at 105μg/m in the presence of UVA. However, no effect was seen in the absence of UV‐A, even at 0.1 μg/m of αT. Mouse cells were much more resistant to αT, as was the bacterial virus T4, which does not contain a membrane. Murine CMV, which had been inactivated by αT and UVA, penetrated mouse cells efficiently; but the viral DNA could not replicate, and late viral proteins were not made. Thus viral gene expression was inhibited in the photoinactivated virus. In order to account for all these data we suggest that αT may interact with viral proteins in addition to membrane lipids.
THE EFFECT OF APPLIED THICKNESS ON SUNSCREEN PROTECTION: IN VIVO AND IN VITRO STUDIES
Authors: Brown S. , Diffey B. L. 
Published: January 2008

AbstractThe effect of applied thickness of sunscreen on the degree of protection against ultraviolet exposure has been investigated using an in vitro model (excised human epidermis) and phototesting in human subjects. The agreement between the protection factors obtained by each technique was excellent. It is shown that the influence of applied thickness on sunscreen protection factors is much less than would be predicted by Beer's law.
A PROTON RELEASE SITE ON THE C‐TERMINAL SIDE OF BACTERIORHODOPSIN
Authors: Li Qingguo , Govindjee Rajni , Ebrey Thomas G. 
Published: January 2008

AbstractWe have studied the pH dependence of the light‐induced proton release and uptake by bacteriorhodopsin. The quantum efficiency of proton release in cell envelopes and proton uptake in phospholipid vesicles is high in the low pH range and begins to decline between pH 6 and 7 in cell envelopes and between pH 7–8 in phospholipid vesicles. In the cell envelope vesicles the proton release increases again above pH 8–8.5; in phospholipid vesicles a proton release is observed before proton uptake at pHs greater than 9. We suggest that the light‐induced proton release observed at high pHs are due to protons released and rebound on the carboxyl terminal side of bacteriorhodopsin.
EXCITATION ENERGY TRANSFER IN THE CRYPTOPHYTES. FLUORESCENCE EXCITATION SPECTRA AND PICOSECOND TIME‐RESOLVED EMISSION SPECTRA OF INTACT ALGAE AT 77 K
Authors: Bruce Doug , Biggins John , Steiner Tom , Thewalt Mike 
Published: January 2008

AbstractExcitation spectra of chlorophyll‐a (Chl‐a) fluorescence in intact cells of Cryptomonas ovata, Chroomonas pauciplastida and Chroomonas salina were determined at 77 K. For all species the excitation spectra for emission from Chl‐a associated with photosystem II (PSII) showed increased contributions by a carotenoid (493 nm) and phycobiliproteins, and decreased contributions by carotenoid (417 nm, 505 nm) and Chl‐a (445 nm) as compared to excitation spectra for emission from Chl‐a associated with photosystem I (PSI). Excitation spectra of C. salina and C. ovata showed an increased contribution by Chl‐c2 to PSII Chl‐a fluorescence emission. In all three species the absorbance band positions of Chl‐a, as determined from the excitation spectra, were similar to those previously described in green plants. green algae and phycobilisome‐containing organisms. Time‐resolved 77 K fluorescence emission spectra of C. ovata and C. salina showed successive emission from both phycoerythrin and Chl‐c2, PSII Chl‐a, and PSI Chl‐a. C. pauciplastida showed successive emission from phycocyanin, PSII Chl‐a, and PSI Chl‐a. Spectral red‐shifts with time were observed for the phycobiliprotein peaks in all three species. The fluorescence decay of phycoerythrin in C. ovata and C. salina was faster than that of phycocyanin in C. pauciplastida. The results are discussed in relation to the organization of the antenna pigments of PSII and PSI in the cryptophyte algae.
AN UNUSUAL EXCITED STATE SPECIES OF ortho‐ HYDROXY‐CINNAMIC ACID*
Authors: Wolfbeis Otto S. , Begum Monowara , Hochmuth Petra 
Published: January 2008

AbstractThe fluorescence of ortho‐hydroxycinnamic acid was studied in aqueous solution over the pH 0‐14 range and in methanol. At pH values above 9.7, intense anion fluorescence is observed. In the pH 4‐9 range emissions are from both the monoanion (albeit weakly) and from the dianion due to photodissociation. In the pH 0‐4 range a blue and a green fluorescence was found, which is attributed to emissions from the unchanged molecule and from an unusual excited state tautomer respectively. The latter is assumed to be the phenolate anion of cinnamic acid and represents a tautomer with no equivalent in the electronic ground state. It is assumed to be formed by adiabatic photodissociation during the lifetime of the first excited singlet state.
FOURIER ANALYSIS OF ANGULAR DISTRIBUTIONS FOR MOTILE MICROORGANISMS
Authors: Hauder Donat‐P. , Lipson Edward D. 
Published: January 2008

AbstractThe method of Fourier transformation is used to analyze histograms of the angular distribution of organisms moving with respect to a stimulus, in this case the light direction. In the Fourier spectra, the components with the highest amplitudes indicate the modality of orientation, i.e. the number of preferred directions, and the corresponding phase values indicate the deviation from the light direction. In the frequency domain, those components with high amplitude and/or those with low frequencies (low‐pass filtering) can be selected and used to reconstruct a smoothed histogram by means of an inverse Fourier transform. This method reduces the noise level and reveals the prominent features of histograms. Examples of unimodal, bimodal and multimodal distributions are shown in their original and smoothed form for the flagellate Euglena gracilis, and for amoebae and pseudoplasmodia or the slime mold Dictyostelium discoideum.
THE THEORY OF PHOTODYNAMIC THERAPY DOSIMETRY: CONSEQUENCES OF PHOTO‐DESTRUCTION OF SENSITIZER
Authors: Potter W. R. , Mang T. S. , Dougherty T. J. 
Published: January 2008

Abstract Photodynamic dose is defined as the area under the curve of sensitizer level plotted as a function of light dose. This is a photochemical definition of dose. We will show that this definition is useful in predicting photobiological response. The photodestruction of sensitizer during photodynamic therapy is shown to result in an upper limit on the photodynamic dose which can be delivered by an unlimited light dose. This limit results in the opportunity to make total photodynamic dose uniform to considerable depths (one to two centimeters). The existence of thresholds for permanent tissue damage allows protection of normal tissue from the large light doses required to achieve this limiting dose deep in the tissue. Higher sensitizer levels in the tumor permit tumor destruction while the normal tissues are protected. A clinical trial to determine the proper level of injected dose necessary for these results is required.This theory of photodynamic therapy (PDT) dosimetry is tested in the DBA‐SMT experimental mouse tumor system. Combinations of drug and light which are not reciprocal but are nearly equal by this theory are shown to give equivalent tumor control at seven days post treatment. Reciprocal combinations of drug and light fail to give equivalent results when they are selected using the theory to choose a combination where reciprocity should fail.
UNCOUPLING OF PHOTOPHOSPHORYLATION BY NITROGENOUS BASES. NO CORRELATION Ofb UNCOUPLING WITH pKb and PARTITION COEFFICIENT
Authors: Lotina‐Hennsen Blas , King Beatriz , Albores Martha , Pozas Rocío 
Published: January 2008

AbstractTwenty six nitrogenous compounds were tested for uncoupling activity from water to methylviologen in spinach chloroplasts. No correlation was found between photophosphorylation and pKb or partition coefficient. Thus basic strength is not related with uncoupling phenomena, suggesting that nitrogenous bases are not protonated during uncoupling. Steric effect is also unimportant for uncoupling. New discovered uncouplers were acetamide, hexylamide and trichloroacetamide, which are all very efficient uncouplers. Acetamide accelerates electron transport and decreases ATP synthesis. However, it increases net proton uptake at low concentration, and collapses proton gradient at high concentration. 1,12 Diaminododecane is also a very efficient uncoupler'but it does not have any relationship with other diamines tested; it causes reversible shrinkage to the chloroplast, which suggests that it is not a detergent type of uncoupler.
AN ACTION SPECTRUM FOR LETHAL PHOTOSENSITIZATION OF Candida albicans BY 8‐MOP AFTER LOW‐DOSE BROAD‐BAND UV‐A IRRADIATION; AN ACTION SPECTRUM FOR 8‐MOP 4′,5′‐ MONOADDUCTS?
Authors: Baydoun Safa A. , Young Antony R. 
Published: January 2008

AbstractAn action spectrum was obtained for lethal photosensitization of Candida albicans that had been pre‐irradiated with a sub‐lethal low dose of broad‐band UV‐A after incubation with 8‐methoxypsoralen and then washed to remove any non‐photobound 8‐methoxypsoralen. The resultant spectrum with a peak in the 320‐335 nm region was similar to that obtained by a conventional method (single irradiation only) and also to the absorption spectrum of the 4′,5′‐monoadduct. These data support the hypothesis that the chromophore for lethal photosensitization by 8‐methoxypsoralen is the 8‐methoxypsoralen/DNA 4′,5′‐monoadduct rather than 8‐methoxypsoralen itself.