bluuebunny/crossref_metadata_2025_split huggingface dataset:
TRANSDUCIN ACTIVATION BY MOLECULAR SPECIES OF RHODOPSIN OTHER THAN METARHODOPSIN II*
Authors: OKADA DAISUKE , NAKAI TOSHIKI , IKAI ATSUSHI 
Published: January 2008

Abstract [1] Decay of metarhodopsin II was accelerated by hydroxylamine treatment or dark incubation of metarhodopsin II at 30°C. The products thus obtained after decay of metarhodopsin II induced GTPase activity on transducin as well as metarhodopsin II suggesting that rhodopsin could activate transducin after the decay of metarhodopsin II intermediate. [2] After urea‐treated bovine rod outer segment membrane was completely bleached, rhodopsin in the membrane was regenerated by the addition of 11‐cis retinal at various temperatures between 0 and 37°C. The capacity to induce GTPase activity on transducin and phosphate incorporating capacity catalyzed by rhodopsin kinase were measured on such rhodopsins. The results showed that: (1) Regeneration of alpha band of rhodopsin was complete regardless of regeneration temperature; (2) When regenerated at temperatures below 10°C, rhodopsins induced a GTPase activity on transducin in the dark even after treatment with hydroxylamine, whereas rhodopsins after regeneration at temperatures above 13°C did not; (3) When regenerated at 0°C, rhodopsin was phosphorylated if incubated with rhodopsin kinase and ATP in the dark, whereas the spectrally regenerated rhodopsin at 30°C was not. The complete quenching of functions of photoactivated rhodopsin was achieved by recombination with 11‐cis retinal at temperatures above 13°C but not below 10°C suggesting the existence of a low temperature intermediate upon regeneration.Nishigonaka, Okazaki 444. Japan.
THE LATE PHASE OF HEMATOPORPHYRIN DERIVATIVE‐INDUCED PHOTOTOXICITY IN MICE: RELEASE OF HISTAMINE and HISTOLOGIC CHANGES
Authors: Nicholas Dan He , Soter A. , Lim Henry W. 
Published: January 2008

Abstract—This study was designed to directly examine the role of mast cells and the histologic changes in the late phase (4–48 h) of hematoporphyrin derivative‐induced phototoxicity. BALB/c mice were rendered phototoxic by intraperitoneal injection of HpD, followed by exposure to 1.59 kj/m2 of 396–406 nm radiation. Immediately before radiation, and at 4, 8, 12, 18, 24 and 48 h after radiation, the ear thickness, serum histamine levels and histologic changes of ears were examined. A maximal net increase in ear thickness of 33.5 ±0.3 times 10‐2 mm (mean ± SE) was noted at 12 h, associated with a maximal net increase of serum histamine (43.3 ± 11.6 ng/ml, mean ± SE), and a maximal mast cell degranulation. Other histologic changes consisted of mild epidermal spongiosis at 18–24 h, and a predominant neutrophilic infiltrate, which peaked at 24 h (211.6 ± 0.4 cells/mm2). No significant alteration was observed in control mice. These data indicated that mast cells participate in the late phase of HpD‐induced phototoxicity in mice.
AN ANALYSIS OF PHYTOCHROME‐MEDIATED THRESHOLD CONTROL OF HYPOCOTYL GROWTH IN MUSTARD (Sinapis alba L.) SEEDLINGS†
Authors: Oelze‐Karow Heidemarie , Mohr Hans 
Published: January 2008

Abstract—Hypocotyl elongation in mustard (Sinapis alba L.) seedlings is known to be controlled by phytochrome (Pfr) through a threshold response. This phytochrome‐mediated threshold response was studied in detail with the following results: (i) The Pfr threshold value required to suppress hypocotyl growth is much lower (0.03% Prr, based on total phytochrome in the hypocotyl at 36 h after sowing = 100%) than those threshold valued observed previously in threshold control by hook phytochrome of appearance of ‘potential capacity for photophosphorylation’ and lipoxygenase appearance in the mustard cotyledons (1.25% Ptr, based on total phytochrome in the hypocotyl at 36 h after sowing = 100%). This probably explains why hypocotyl elongation is so extremely sensitive to light, (ii) The Pfr threshold value controlling hypocotyl growth is a system constant, independent of total phytochrome content, developmental age and actual growth rate, (iii) Threshold control of hypocotyl elongation is unaffected by the removal of the cotyledons and half of the hook. However, removal of the whole hook totally eliminates any light control over the residual hypocotyl growth, (iv) After termination of the threshold control, the hypocotyl growth rate immediately returns to precisely that found in untreated dark control even though the partial growth rates of the different parts of the hypocotyl are quite different, relative to their dark controls. Obviously, the organ grows as an integrated unit.It is concluded that the all‐or‐none threshold control over hypocotyl growth is exerted from the plumular hook. It appears that the hook can send off phytochrome all‐or‐none signals in both directions, to the cotyledons and to the hypocotyl.
PHOTOREACTIVATION OF LETHAL DAMAGE AND DAMAGE LEADING TO CHROMATID DELETIONS INDUCED IN G1 PHASE HAMSTER x Xenopus HYBRID CELLS BY UV
Authors: Kulp Susan Q. , Griggs H. Gaston 
Published: January 2008

Abstract—A86 Xenopus cells, cloned from a Xenopus line that exhibited a high level ot photoreacti‐vation of UV‐induced lethal damage, and V79M1 hamster cells, cloned from a hamster line that did not exhibit efficient photoreactivation of such damage, were fused to produce the V79M1 A86 cell line ‐ a hybrid line in which approximately 84% of the cells contained the entire V79M1 and A86 genomes. Ultraviolet and UV plus photoreactivation fluence‐survival relations were then determined and compared for hybrid and parental Gl phase cells in a first attempt to elucidate interactions of the parental genetic potentials for photoreactivation in the hybrid. Specifically, it was anticipated that the combined V79M1 and A86 genomes in the hybrid would produce photoreactivating enzymes sufficient to efficiently photoreactivate UV‐induced lethal damage in both A86 and V79M1 DNA and little difference would be observed in the levels of photoreactivation exhibited by V79M1 A86 and A86 Gl phase cells. To the contrary, the level of photoreactivation observed for the hybrid did not closely approach that observed for the A86 line. To assist in the interpretation of this somewhat unexpected observation, three additional studies were performed: (1) comparison of ‘optimal’ schemes for photoreactivation of UV‐induced lethal damage in the hybrid and parental Gl phase cells, (2) comparison of the effects of some different types of growth medium on photoreactivation of UV‐induced lethal damage in hybrid and parental Gl phase cells, and (3) comparison of the levels of photoreactivation of UV‐induced chromatid deletions in the V79M1 and A86 chromosomes of Gl phase hybrid cells. The results suggested that the relatively low level of photoreactivation of UV‐induced lethal damage manifested by the hybrid cells could be attributed, at least in part, to their inability to efficiently photoreactivate pyrimidine dimers induced in the DNA of their V79M1 chromosomes.
QUANTUM YIELDS FOR LASER PHOTOCYCLIZATION OF BILIRUBIN IN THE PRESENCE OF HUMAN SERUM ALBUMIN. DEPENDENCE OF QUANTUM YIELD ON EXCITATION WAVELENGTH
Authors: McDonagh Antony F. , Agati Giovanni , Fusi Franco , Pratesi Riccardo 
Published: January 2008

Abstract—The quantum yield for laser photocyclization of bilirubin to lumirubin in the presence of human serum albumin (tHLR) was measured at five monochromatic excitation wavelengths in the range 450–530 nm. Solutions used were optically thin throughout the wavelength range and precautions were taken to exclude contributions from photocyclization of bilirubin XHIa impurities. The values obtained (7.2‐18 10‐4) were lower than those previously reported and showed the following wavelength dependence: 457.9 < 488.0 < 501.7 < 514.5 528.7. However, the rate of lumirubin formation, normalized to constant fluence, decreased with wavelength over the same wavelength range and no evidence was found that photoisomerization of bilirubin to lumirubin is faster with green (514.5 or 528.7 nm) than with blue (457.9 or 488.0 nm) light. The stereoselectivity of the configurational isomerization of bilirubin to 4Z,15E and 4E,15Z isomers also was studied. This reaction became less regioselective for the 4Z,15E isomer with increasing wavelength. The observed wavelength dependence of tHLR and of the [4Z,15E]: [4Z,15E] ratio at photoequilibrium are consistent with an exciton coupling model in which intramolecular energy transfer can occur between the two pyrromethenone chromophores of the bilirubin molecule in the excited state. Relative rates of lumirubin formation in vivo at different excitation wavelengths and constant fluence were estimated for different optical thicknesses and for different skin thicknesses. These estimates suggest that the recently reported clinical equivalence of blue and green phototherapy lights probably reflects the marked variation of skin transmittance with wavelength more than wavelength‐dependent photochemistry. The calculations also indicated that the optimal wavelength for phototherapy is probably on the long wavelength side of the bilirubin absorption maximum.
FLUORESCENCE SPECTROSCOPY OF BENZO[a]PYRENE DIOL EPOXIDE‐DNA ADDUCTS. CONFORMATION‐SPECIFIC EMISSION SPECTRA
Authors: Kim Seog K. , Brenner Henry C. , Soh Byoung Joon , Geacintov Nicholas E. 
Published: January 2008

Abstract—The fluorescence characteristics of adducts derived from the covalent binding of the highly tumorigenic (+) and the non‐tumorigenic (‐) enantiomers of trans‐7,8‐dihydroxy‐anti‐9,10‐epoxy‐7,8,9,10‐tetrahydrobenzo[a]pyrene (BPDE) to native calf thymus DNA are significantly different from one another both at room temperature and at 77 K. The ratio R of fluorescence intensities of the (0,0) band I (situated near 380 nm) and vibronic band V (near 400 nm) of the pyrene ring system in the BPDE‐DNA adducts and of the tetraol (BPT) hydrolysis product of BPDE is very sensitive to the polarity of the solvent, thus mimicking the well known behavior of pyrene itself (A. Nakajima, 1971, Bull. Chem. Soc. Jpn. 44, 3272). The fluorescence excitation and emission spectra of the(+)‐BPDE‐DNA adducts are relatively sharp and only slightly red‐shifted (2–3 nm) with respect to those of BPT in aqueous buffer solution, and R= 1.07 when the fluorescence is excited at the maximum of the absorption spectrum; this compares with R= 1.17 for BPT in water, R= 0.75 in ether, and R= 0.84 for noncovalently intercalated BPT. These results suggest that the pyrene ring system in the covalent (+)‐BPDE‐DNA adducts is located in an environment which is relatively exposed to the aqueous environment, while physically intercalated BPT molecules are located at hydrophobic binding sites. The fluorescence characteristics of the (‐)‐BPDE‐DNA adducts are more heterogeneous and thus more complex than those of the (+)‐adducts. The R ratio depends rather strongly on the wavelength of excitation; a minor, more highly fluorescent and relatively solvent‐accessible form of adducts exhibits an R ratio of 1.01. The major, less solvent accessible form is characterized by a larger red shift in the absorption spectrum (10 nm) and emission spectrum (6 nm for the (0,0) band) relative to BPT, and an R ratio of 1.07. These characteristics suggest that the local environments of the pyrenyl residues in the (‐)‐BPDE‐DNA adducts are significantly different from those of BPT bound noncovalently to DNA by the intercalation mechanism. Fluorescence methods, particularly at low temperatures where the bands are better resolved and the fluorescence yields are significantly greater than at room temperature, can also be used to distinguish covalent DNA adducts derived from the binding of (+)‐BPDE and (‐)‐BPDE to native double‐stranded DNA.
REACTIVITY OF CHLOROPHYLL a/b‐PROTEINS AND MICELLAR TRITON X‐100 COMPLEXES OF CHLOROPHYLLS a OR b WITH BOROHYDRIDE
Authors: Scheer Hugo , Porra Robert J. , Anderson Jan M. 
Published: January 2008

Abstract—The reaction of several plant chlorophyll‐protein complexes with NaBH4has been studied by absorption spectroscopy. In all the complexes studied, chlorophyllbis more reactive than Chia,due to preferential reaction of its formyl substituent at C‐7. The complexes also show large variations in reactivity towards NaBH4and the order of reactivity is: LHCI > PSII complex > LHCII > PSI > P700 (investigated as a component of PSI). Differential pools of the same type of chlorophyll have been observed in several complexes.Parallel work was undertaken on the reactivity of micellar complexes of chlorophyllaand of chlorophyllbwith NaBH4to study the effect of aggregation state on this reactivity. In these complexes, both chlorophyll a andbshow large variations in reactivity in the order monomer > oligomer > polymer with chlorophyllbgenerally being more reactive than chlorophylla.It is concluded that aggregation decreases the reactivity of chlorophylls towards NaBH4in vitro,and may similarly decrease reactivity in naturally‐occurring chlorophyll‐protein complexes.
POTENTIAL EFFECTS OF UV‐B RADIATION ON MARINE ORGANISMS OF THE SOUTHERN OCEAN: DISTRIBUTIONS OF PHYTOPLANKTON AND KRILL DURING AUSTRAL SPRING
Authors: Bidigare R. R. 
Published: January 2008

AbstractIncreases in UV‐B radiation resulting from ozone depletion during austral spring could potentially alter the balance of the Southern Ocean marine ecosystem. A quantitative assessment ol the effects of UV‐B enhancement requires knowledge of (1) the wavelength‐dependent fluxes of UV‐B in the upper ocean, (2) action spectra for UV‐B damage to Antarctic phytoplankton and zooplankton, and (3) depth‐dependent distributions and residence times of Southern Ocean phytoplankton and zooplankton during austral spring. Unfortunately, only limited data arc currently available to address this impact directly. To provide some of the information required for such an assessment, available data regarding plankton distributions and their photophysiological characteristics have been summarized. A preliminary assessment of the available literature suggests that Antarctic phytoplankton and krill receive very low doses of UV‐B during austral spring. The high spectral attenuation coefficients associated with the environments in which most plankton arc found during springtime precludes the possibility of UV damage. Future research directions are described which should provide a better understanding of the ecological consequences of the “ozone hole” which resides over the Antarctic continent during austral spring.
EFFECTS OF ULTRAVIOLET RADIATION ON THE IMMUNE SYSTEM IN HUMANS
Authors: Morison Warwick L. 
Published: January 2008

Abstract–In experimental animals, exposure to UV‐B radiation produces selective alterations of immune function which are mainly in the form of suppression of normal immune responses. This immune suppression is important in the development of nonmelanoma skin cancer, may influence the development and course of infectious disease and possibly protects against autoimmune reactions. The evidence that this form of immune suppression occurs in humans is less compelling and very incomplete. The wavelengths of radiation most affected by a depletion of the stratospheric ozone layer are those known to be most immunosuppressive in animals and it is likely that such depletion will increase any suppressive effect of sunlight on immunity in humans. In addition to establishing whether or not UV‐B radiation can cause suppression of immune function in humans, studies are required to determine if melanin can provide protection against such suppression, the role of this suppression in the pathogenesis of skin cancer, the development of infectious disease and vaccine effectiveness, and the capacity for humans to develop adaptive, protective mechanisms which may limit damage from continued exposure to UV‐B radiation.
EFFECTS OF ULTRAVIOLET LIGHT ON THYMIDINE INCORPORATION AND DNA CHAIN ELONGATION IN PHOTOREACTIVABLE INSECT CELLS
Authors: Styer Susan C. , Meechan Paul J. , Griffiths T. Daniel 
Published: January 2008

Abstract–An insect cell line, IAL‐PID2, was exposed to UV and analyzed for its ability to incorporate [3H]‐thymidine and to elongate replicon‐sized DNA fragments. After exposure to 5 or 10 J/m2 UV, the cells exhibited a rapid and prolonged depression in the rate of thymidine incorporation. Photoreactivation reduced this depression but did not entirely reverse it. For exposures of 5 J/m2 or above, full recovery did not occur until 18 h after exposure. The blockage of fork progression after UV exposure was fluence‐dependent, with replication segments after exposure to 20 J/m2 being shorter than those observed after exposure to 10 J/m2. Immediately after exposure to either 10 or 20 J/m2, photoreactivation reversed blockage of fork progression, indicating that the (5–6) cyclobutyl pyrimidine dimer is responsible for blockage. This also indicates that blockage of fork progression may not be the only factor responsible for the prolonged depression seen in thymidine incorporation. Three hours after exposure to either 10 or 20 J/m2, replication segments were still significantly shorter than control segments. Photoreactivation completely reversed blockage after exposure to 10 J/m2, but did not completely reverse blockage after exposure to 20 J/m2, indicating that at such fluences, other lesions may play a role in UV‐induced blockage of fork progression.
EFFECTS OF SOLAR RADIATION ON DEVELOPMENT IN THE CELLULAR SLIME MOLD, Dictyostelium discoideum
Authors: Häder Donat‐P. , Hader Maria 
Published: January 2008

Abstract–The effect of solar radiation on development was studied in two strains (wild type N04 and axenic AX2) of the cellular slime mold, Dictyostelium discoideum. In both strains early development was retarded by solar radiation and amoebae exposed for >200 min never developed into mature sorocarps. Overheating can be excluded as a mechanism for inhibition since the organisms were exposed in a temperature‐controlled growth chamber. The most effective component seems to be UV‐B radiation (while UV‐A has a smaller inhibitory effect) as shown by cutting off shorter wavelength radiation using WG filters.
EVALUATION OF SULFONATED ALUMINUM PHTHALOCYANINES FOR USE IN PHOTOCHEMOTHERAPY. A STUDY ON THE RELATIVE EFFICIENCIES OF PHOTOINACTIVATION
Authors: BERG KRISTIAN , BOMMER JERRY C. , MOAN JOHAN 
Published: January 2008

AbstractThe cellular photosensitivity caused by aluminum phthalocyanines sulfonated to different degrees (AlPcSn) has been investigated. The phototoxic effect increased with decreasing number of sulfonate groups on the macrocycle, with the exception of AlPcS, which was less phototoxic than AlPcS2 but more phototoxic than AlPcS, and AlPcS4. The tendency of the AlPcSns to aggregate in our cellular system increased with increasing lipophilicity of the sensitizers. The aggregates had little or no photosensitizing activity. The low efficiency of cell inactivation caused by AlPcS1 can be explained by the highly aggregated state of this sensitizer in the cells. AlPcS2 and AlPcS3 induced a lower degree of cell inactivation per fluorescing quantum and per quantum absorbed by monomeric species than did AlPcS, and AlPcS,. AlPcS4 and AlPcS3 are therefore suggested to be in different intracellular locations than AlPcS2 and AlPcS1.
UROCANIC ACID ANALOGUES AND THE SUPPRESSION OF THE DELAYED TYPE HYPERSENSITIVITY RESPONSE TO Herpes simplex VIRUS
Authors: NORVAL M. , SIMPSON T. J. , BARDSHIRI E. , HOWIE S. E. M. 
Published: January 2008

AbstractUltraviolet irradiated urocanic acid (4‐imidazoleacrylic acid) containing a mixture of cis‐and trans‐isomers has been shown previously to induce suppression of the delayed type hypersensitivity (DTH) response to Herpes simplex virus type 1 (HSV‐1) in a murine model of infection. The cis‐isomer of urocanic acid was prepared and the cis‐ and trans‐isomers of 2‐methylurocanic acid, 2‐pyrroleacrylic acid, 2‐furanacrylic acid, 2‐thiopheneacrylic acid, 3‐thiopheneacrylic acid as well as dihydrourocanic acid and histamine. Each was applied at concentrations of 1 and 50 mUg per mouse to the shaved dorsal skin and the mice were infected subcutaneously with HSV 5 h later. After 8–10 days the DTH response to the virus was measured by an ear swelling test. It was found that cis‐urocanic acid was effective in suppressing the DTH response at levels of 1 mUg per mouse or less. The cis‐ and frww‐isomers of 2‐furanacrylic acid, 2‐pyrroleacrylic acid and 2‐thiopheneacrylic acid were also effective, with the cis‐ form generally being more active than trans, and 2‐pyrroleacrylic acid being particularly potent. Cis‐ and trans‐3‐thiopheneacrylic acid, on the other hand, were only marginally immunosuppressive while neither isomer of 2‐methylurocanic acid had any suppressive ability. Dihydrourocanic acid and histamine were also shown to suppress the DTH response. Thus the structural features necessary for urocanic acid and its analogues to act as mediators of UV‐induced immunosuppression could be deduced and implications for their mechanism of action discussed.
LUX C, D AND E GENES OF THE Vibrio fischeri LUMINESCENCE OPERON CODE FOR THE REDUCTASE, TRANSFERASE, AND SYNTHETASE ENZYMES INVOLVED IN ALDEHYDE BIOSYNTHESIS
Authors: BOYLAN M. , MIYAMOTO C. , WALL L. , GRAHAM A. , MEIGHEN E. 
Published: January 2008

AbstractThe lux C, D, and E genes of the Vibrio fischeri luminescence operon code for three polypeptides of 54, 33, and 42 kDa, respectively, which are required for synthesis of the aldehyde substrate for the luminescent reaction. These polypeptides have been identified in V. fischeri and V. harveyi as well as in recombinant E. colt harboring the cloned genes by specific acylation with [3H]fatty acid, showing that they are components of a fatty acid reductase system with reductase, synthetase and transferase activities. By using glycerol in the assay and/or extraction buffer and decreasing the reducing agent, the levels of the acylation of the 54 and 42 kDa polypeptides have been greatly increased. As a consequence, it was possible to demonstrate that the 54 kDa polypeptide coded by the lux C gene has reductase activity. In a subclone missing the lux E gene, the 42 kDa polypeptide was missing and the 54 kDa polypeptide could not be acylated in vitro with tetradecanoic acid (+ATP) and only to a low level in vivo indicating that the synthetase enzyme, responsible for fatty acid activation, is coded by the lux E gene. In vitro acylation with tetradecanoyl CoA of the 33 kDa polypeptide coupled with the specific cleavage of acyl‐ACP only in E. coli extracts transformed with DNA containing the lux D gene, demonstrated that the lux D gene coded for the transferase enzyme.
A PORPHYRIN‐DNA EXCIPLEX: RESONANCE RAMAN SPECTRA OF ELECTRONICALLY EXCITED Cu(TMpy‐P4) BOUND TO POLY(dA‐dT)‐POLY(dA‐dT)
Authors: Turpin P. Y. , Chinsky L. , Laigle A. , Tsuboi M. , Kincaid J. R. , Nakamoto K. 
Published: January 2008

AbstractThe resonance Raman spectra of water‐soluble porphyrins, Cu(TMpy‐P4) and Ni(TMpy‐P4), and their mixtures with DNA, Poly(dG‐dC)‐Poly(dG‐dC), and Poly(dA‐dT)‐Poly(dA‐dT) were measured using 426 nm pulsed laser excitation (and 556 nm for some applications). At high laser power, the solution of Cu(TMpy‐P4) mixed with DNA or Poly(dA‐dT)‐Poly(dA‐dT) exhibits new bands at 1550 and 1349 cm−1 that are not observed for Cu(TMpy‐P4) alone or for Cu(TMpy‐P4) mixed with Poly(dG‐dC)‐Poly(dG‐dC). These extra bands do not appear when the resonance Raman spectra are measured by a cw laser or by a pulsed laser with low power. Similar mixtures of M(TMpy‐P4) (where M = Ni, Zn, Co, Mn, and H2) with these nucleic acids exhibit no such bands even by high power pulsed laser excitation. We attribute the new resonance Raman bands to an electronically excited Cu(TMpy‐P4), stabilized by forming an exciplex with the A‐T site of the nucleic acid. The minimum lifetime value of such an exciplex was estimated to be on the order of 10 ps.