bluuebunny/crossref_metadata_2025_split huggingface dataset:
ISOLATION, CHARACTERIZATION AND RECONSTITUTION OF PHYCOBILIPROTEIN ROD‐CORE LINKER POLYPEPTIDE COMPLEXES FROM THE PHYCOBILISOME OF Mastigocladus laminosus*
Authors: Glauser Manuel , Sidler Walter , Zuber Herbert 
Published: January 2008

AbstractA rod‐core complex, (αβ)6PC. LRC29.5,(αβ)3APC.LC8.9, composed of hexameric phycocyanin (PC) and trimeric allophycocyanin (APC) subcomplexes associated to the CpcG2 gene product, has been isolated from the phycobilisome of Mastigocladus laminosus. Exactly the same complex was obtained by reconstitution using the subcomplexes(αβ)3PC. LRC 29.5 and (aβ)3APC.LC8.9 as educts. Spectroscopic analysis of the isolated PC‐LR and PC‐LRC complexes from M. laminosus shows that the LRC cause the largest red‐shift in the absorbance and fluorescence emission maxima of PC. These results indicate that LRC mediate PC‐APC interactions in vitro. Only the CpcG2 polypeptide was able to promote this specific interaction, as neither CpcG3‐PC nor, as a negative control, CpcC‐PC complexes showed any reconstitution products with the core subcomplex (αβ)3APC.Lc8.9. This is an indication that each of the four LRC in the phycobilisomes of M. laminosus and Anabaena sp. PCC 7120 attaches two peripheral rods specifically to one of four different core binding sites.
PHOTOPHYSICAL PROPERTIES OF 3,3′‐DIALKYLTHIACARBOCYANINE DYES IN HOMOGENEOUS SOLUTION
Authors: Krieg Marianne , Redmond Robert W. 
Published: January 2008

AbstractThe photophysical properties of 3,3′‐dialkylthiacarbocyanine iodides and chlorides were measured in various solvents. It was found that photoisomerization and fluorescence are the major contributors to the deactivation of the excited singlet state; intersystem crossing occurs with only a very low efficiency. In ethanol, a triplet yield of 0.004 and a singlet oxygen quantum yield of 0.002 were determined. The photophysical parameters of these dyes are not substantially influenced by the length of the alkyl chain or the size of the halide counterion. The substitution of an ethyl with an octadecyl‐chain only slightly hinders photoisomerization, and the replacement of the chloride with an iodide reduces only marginally the fluorescence lifetimes and fluorescence quantum yields in chloroform. A significant external heavy‐atom effect is observed using dibromoethane as a solvent: triplet and singlet oxygen yields increase7–10‐fold, and the triplet lifetime decreases from 55 μs to 15 mUs.
TIME‐GATED FLUORESCENCE IMAGING FOR THE DIAGNOSIS OF TUMORS IN A MURINE MODEL
Authors: Cubeddu R. , Canti G. , Taroni P. , Valentini G. 
Published: January 2008

AbstractA system for time‐gated fluorescence imaging was used to perform measurements on tumor‐bearing mice treated with hematoporphyrin derivative (HpD). The aim of the study was to define the potential of this technique in the diagnosis of tumors by taking advantage of the long fluorescence lifetime of the exogenous dye with respect to the decay times of the natural fluorescence. After the administration of three different drug doses (5, 10 and 25 mg/kg body weight), fluorescence images were acquired at various uptake times (from 2 h to 10 d), to determine the best instrumental conditions and experimental procedure for the detection of tumors in the murine model considered. The optimal fluorescence contrast between the tumor area and the surrounding healthy tissue was found at 12 h after the administration of either 5 or 10 mg/kg HpD and was anticipated at 8 h for the highest drug dose. In this optimum condition, the tumor region could be identified even after the injection of 5 mg/kg HpD. A better fluorescence contrast was always obtained in 15 ns‐delayed images with respect to synchronous ones.
THE UNUSUAL UVA‐DEPENDENT ANTIVIRAL PROPERTIES OF THE FUROISOCOUMARIN, CORIANDRIN
Authors: Hudson J. B. , Graham E. A. , Harris L. , Ashwood‐Smith M. J. 
Published: January 2008

AbstractThe novel furoisocoumarin, coriandrin, which was found recently to possess an interesting combination of photobiological properties, was investigated for antiviral activity in the presence and absence of UVA (long‐wavelength ultraviolet radiation). In contrast to results obtained with other antiviral furocoumarins, such as 8‐MOP (8‐methoxypsoralen), coriandrin was much more phototoxic to the RNA‐virus Sindbis virus than to the DNA‐virus murine cytomegalovirus, although both viruses were substantially more sensitive to this compound than they were to 8‐MOP. Human immunodeficiency virus, HIV‐1, was also susceptible to coriandrin + UVA.Another unexpected finding was that viruses without membranes were completely resistant to coriandrin. This suggests that a membrane component was a target for the compound. The antiviral activity of coriandrin was profoundly inhibited by serum components in the reaction mixtures, which suggests that the compound may have a strong affinity for certain protein or lipid materials, although maximal interference was only obtained when all components of the reaction mixture, virus, coriandrin and serum, were irradiated simultaneously.Thus it appears that coriandrin has unusual antiviral properties that would not be predicted from its chemical similarity to furocoumarins.
DNA NICKING BY ULTRAVIOLET RADIATION IS ENHANCED IN THE PRESENCE OF IRON and OF OXYGEN
Authors: Audic Annie , Giacomoni Paolo U. 
Published: January 2008

AbstractDouble‐stranded covalently closed circular supercoiled DNA (ccc DNA) from plasmid pUK 9 was irradiated in vitro at denned wavelengths in the UV region (290, 313 and 365 nm). The nicking was monitored by electrophoresis on agarose gels, ethidium staining and densitometric quantitation of supercoiled and relaxed moieties. At the explored wavelengths, the dose required for introducing one nick per million phosphodiester bonds diminishes with increased concentration of added ferric iron, whereas the effect of cupric iron is practically negligible. Adding metal chelators or bubbling argon prior to the irradiation results in a dramatic increase in the dose required for introducing one nick per million phosphodiester bonds. Taken together, these results seem to indicate that iron and oxygen play a role as cofactors in the UV‐induced nicking of ccc DNA in vitro.
MOLECULAR CHANGES DURING THE PHOTOOXIDATION OF α‐CRYSTALLIN IN THE PRESENCE OF UROPORPHYRIN
Authors: Dillon James , Chiesa Raul , Wang Ren‐Hong , McDermott Martin 
Published: January 2008

AbstractSinglet oxygen reacts preferentially with three amino acids in proteins, His, Trp and Met. In order to study the specific molecular events that result from such oxidations, calf a‐crystallin was photooxidized in the presence of uroporphyrin and the reactions were investigated by high performance liquid chromatography peptide mapping using a photodiode array detector followed by fast atom bombardment mass spectrometry (FAB‐MS). From these studies, the following conclusions can be inferred: (1) Upon photooxidation residue Met‐68 of the B chain is oxidized to Met sulfoxide, whereas residue Trp‐60 remains intact. (2) Two of the 16 His residues in a‐crystallin are photooxidized with an apparent pKa of ca 7.0. (3) FAB‐MS analysis suggests that residue Lys‐166 close to the C‐terminal end of the A chain forms a cross‐link with the His‐7 residue close to the N‐terminal end of the A chain. This may be either an inter‐ or intramolecular cross‐link.
PHOTON EMISSION BY BACTERIA CHALLENGED WITH PHENYLACETALDEHYDE. A POSSIBLE DISTINCTION BETWEEN GRAM‐POSITIVE and GRAM‐NEGATIVE BACTERIA
Authors: Surpili Marcelo José , Faijoni‐Alario Adelaide , Cilento Giuseppe 
Published: January 2008

AbstractWith all bacteria tested, addition of phenylacetaldehyde leads to light emission. The latter is markedly stronger with gram‐negative bacteria, presumably because they possess a thinner wall and an extra external lipophilic membrane. Consistent with this explanation, the bactericidal effect of phenylacetaldehyde is also stronger with gram‐negative bacteria.The spectrum of the emitted light shows maximal emission in the 500 nm region and is very similar to that observed when a protein (bovine serum albumin), free amino acids or isopropylamine reacts with phenylacetaldehyde.
ROLES OF URACIL‐DNA GLYCOSYLASE AND APYRIMIDINIC ENDONUCLEASES IN THE MOLECULAR 5‐BROMO‐2′‐DEOXYURIDINE PHOTOSENSITIZATION IN Escherichia coli K‐12
Authors: Yamamoto Yoko , Fujlwarat Yoshisada 
Published: January 2008

AbstractThe molecular mechanism for 5‐bromo‐2′‐deoxyuridine (BrdU) photosensitization was studied in thymine‐requiring wild‐type and uracil‐DNA glycosylase (UDG)‐deficient ung mutant cells of Escherichia coli K‐12. Wild‐type cells were more sensitive to BrdU photosensitiLation than ung mutant cells. IJV induced the identica/ numbers of alkaline sucrose single‐strand breaks (SSB) in 5‐bromouracil‐DNA (BrU‐DNA) of both the wild type and ung mutant. The ung mutant cells repaired SSB almost completely, whereas the wild‐type cells with UDG produced more adverse SSB by 90 min after UV. Neutral agarose gel electrophoresis of minipreps indicated that UV induced (1) more smears of host BrU‐DNA possibly by more double‐strand breaks (DSB) and (2) a greater decline of pBR322 Form I BrU‐DNA in the wild‐type cells than the ung cells. These results indicated a greater induction of SSB by apyrimidinic (AP) endonucleases in wild‐type cells. The ung/wild ratios (=1.7–1.9) for cellular and plasmid BrdU sensitizations aftcr growth in 50% BrdU were similar. The extents of UDG‐dependent and UDG‐independent sensitizations in wild‐type cells were ∼40 and ∼60%, respectively. The xth nfo double mutant defective in both exonuclcase III and endonucleasc IV was more sensitive to BrdU photosensitization than the wild type, indicating that an excess of AP sites remaining after uracil excision in the xth nfo mutant causes a greater BrdU photosensitization than SSB by AP endonucleases in wild‐type cells. Conversely, the xth rfo ung triple mutant was more resistant to BrdU photosensitization than the xth nfo double mutant, so that UV‐induced uracil residues in the BrU‐DNA are tolerated and do not appear to be directly responsible for BrdU photosensitization.
PILOT STUDY ON LIGHT DOSIMETRY FOR ENDOBRONCHIAL PHOTODYNAMIC THERAPY
Authors: Marijnissen Johannes P. A. , Baas Paul , Beek Johan F. , Moll Jan H. van , Zandwijk Nico van , Star Willem M. 
Published: January 2008

AbstractEndobronchial photodynamic therapy (EB‐PDT) using photofrin as the photosensitizer is currently being evaluated as a new treatment modality for inoperable endobronchial tumors. One of the current problems with EB‐PDT is the lack of adequate light dosimetry, which hampers proper interpretation of treatment results. In this study exploratory light dosimetry experiments were performed in plastic bronchus models using either a microlens‐tipped fiber (suitable for illumination of small superficial tumors) or a cylindrical diffuser fiber (suitable for intraluminal illumination or interstitial illumination of partially obstructing tumors). It is shown that the light fluence prescriptions of current clinical protocols yield a different fluence in tissue for each illumination modality. Depending on the actual placement of the cylindrical diffuser within the lumen, the light fluence at 5 mm depth in the homogeneous tissue model may vary by a factor of 3. The results were confirmed by in vivo experiments in the trachea of a pig. There is a possibility of enhanced tissue response by accidental hyperthermia induced during EB‐PDT. The temperature rise was therefore estimated in vivo using a rat tumor model to mimic clinical EB‐PDT. Temperature rises of at least 5°C and 10°C can be expected for intraluminal and intratumoral illumination, respectively, at 3.5 ± 1 mm depth in tissue and 400 mW/cm diffuser output. Light fluence and its distribution in the bronchus strongly depend on the geometry and the optical properties of the tissue as well as on the technique of illumination. As a result of inadequate dosimetry, significant variations in treatment response between patients may be expected.
SYNTHESIS AND PHOTOBIOLOGICAL PROPERTIES OF 4‐HYDROXYMETHYL‐4′‐METHYLPSORALEN DERIVATIVES
Authors: Zagotto G. , Gia O. , Baccichetti F. , Uriarte E. , Palumbo M. 
Published: January 2008

AbstractThe synthesis and the photobiological activity of two new hydroxymethyl derivatives of psoralen namely 4‐hydroxymethyl‐4′‐methyl‐ and 4‐hydroxymethyl‐4′‐methyl‐8‐rnethoxypsoralen are described. Both compounds exhibited efficient photobinding to DNA and RNA. The DNA‐photobinding process was investigated using different nucleic acid structures such as double‐helical DNA, ribosomal RNA, bacterial DNA and DNA organized in the nucleosomal arrangement. The test derivatives were able to induce cross‐links to a similar extent as 8‐methoxypsoralen (8‐MOP), used as a reference photochemotherapeutic drug. In contrast to 8‐MOP, they produced relatively high levels of lO2. Most photobiological effects (DNA synthesis inhibition, T2 phage sensitization, inhibition of tumor transmitting capacity) showed a good correlation with the extent of covalent photoaddition. On the other hand, the new 4‐hydroxymethylpsoralens were unable to induce skin erythema, in striking contrast with 8‐MOP. Thus, neither cross‐linking of the nucleic acid nor 1O2 production were coupled with skin phototoxicity in this class of compounds. The new derivatives appear to represent an important beginning to development of new active photochemotherapeutic agents devoid of undesired phototoxic side effects.
EFFECTS OF ARCTIC OZONE DEPLETION AND SNOW ON UV EXPOSURE IN FINLAND
Authors: Jokela Kari , Leszczynski Kirsti , Visuri Reijo 
Published: January 2008

AbstractThe increase in the UV exposure of the Finnish population associated with the combined effects of ozone depletion and snow reflection was studied with the aid of theoretical calculations based on Green's clear sky UV model. A simple formula was utilized to transform horizontal irradiances to vertical irradiances averaged over 360 azimuth angle. The model was verified with spectral and broadband measurements. The difference between the theoretical and measured UV radiation falling to horizontal surfaces was in most cases less than ±10%, and the additional error to theoretical vertical irradiances was less than ± 10%. The calculations show that the annual horizontal doses in Helsinki (60.2°N, 25°E) are about 35% higher than in Saariselkä (68.4°N, 27.5°E), but the difference is only 16% for vertical doses owing to the stronger contribution to vertical (facial) surfaces of the reflection of UV from snow. At Saariselkä, the maximum vertical irradiance at the end of April approaches the midsummer values. The ozone depletions up to 40% in February and March 1992 had no significant effect on the annual doses because the total ozone returned to normal before the UV increased to biologically significant levels.
LIGHT‐DRIVEN H2 PRODUCTION WITH PROFLAVIN AND HYDROGENASE: COMPARISON OF CYTOCHROME C3 AND METHYL VIOLOGEN AS e‐ MEDIATORS
Authors: Eng Lars H. , Lewin Mona B.‐M. , Neujahr Halina Y. 
Published: January 2008

AbstractWe have studied the hydrogenase‐catalyzed production of H, when either its natural electron mediator cytochrome c3 (c3) or the artificial mediator methyl viologen (MV) was reduced by illumination of proflavin (PF) in the presence of ethylenediaminetetraacetate (EDTA). The reduction rates of MV and c3 were comparable at equivalent concentrations of PF, taking into account the four redox sites of c3. However, when the concentration of c3 exceeded that of PF, the reduction rate decreased. We explain this by light quenching. In the H2‐producing system, MV was more efficient than c3 as electron mediator when the initial reaction rates were compared. However, under certain conditions with MV, the rate of H2 production decreased rapidly with time of illumination, whereas with c3 it consistently remained stable. Possible reasons for this difference are discussed.Severe inactivation of hydrogenase was observed in the absence of the primary electron donor EDTA. It is concluded that this inactivation is caused by the excited state of PF
4‐THIOURIDINE INCORPORATION INTO THE RNA OF MONKEY KIDNEY CELLS (CV‐1) TRIGGERS NEAR‐UV LIGHT LONG‐TERM INHIBITION OF DNA, RNA AND PROTEIN SYNTHESIS
Authors: Favre Alain , Moreno Giuliana , Salet Christian , Vinzens Francloise 
Published: January 2008

AbstractMonkey kidney cells (CV‐1) grown for 4 h in the presence of 0.1 mM 4‐thiouridine (s4Urd) incorporate this photoactivable uridine analog in their RNA. A minor, 5–8%, thiolated RNA fraction can be isolated from bulk RNA by affinity chromatography. This RNA fraction contains 1.5–2.5 s4Urd residues per 100 nucleotides and exhibits a broad chain length distribution ranging from 700 to 7000 nucleotides. It is essentially of nuclear origin and amounts to 30% of the RNA synthesized during exposure of cells to s4Urd. Under the same s4Urd labeling conditions, no thiolated pyrimidine residues have been detected in DNA.Irradiation with 365 nm light (45 kJ/m2) of the cells immediately after s4Urd exposure triggers long‐term inhibition of DNA, RNA and protein synthesis accompanied by a linear decline (50% in 2 days) in the total cell mass of cultured cells. In contrast, exposure to s4Urd alone results in moderate but reversible inhibitory effects. The available data suggest that s4Urd‐induced photolesions in newly synthesized RNA such as RNA‐RNA cross‐links as well as RNA‐protein bridges are directly involved in impairment of essential cellular functions.
STIMULATION OF APPEARANCE OF EXTRAPLASTIDIC TETRAPYRROLES BY A PHOTOOXIDATIVE TREATMENT OF THE PLASTIDS*
Authors: Thomsen Björn , Oelze‐Karow Heidemarie , Schuster Christa , Mohr Hans 
Published: January 2008

AbstractIn the mustard seedling (Sinapis alba L.) the appearance of photodetectable phytochrome and synthesis of relatively abundant cytosolic hemoproteins (nitrite reductase, ascorbate peroxidase) are stimulated rather than impaired by a photooxidative treatment of the plastids. While the ability to synthesize protoporphyrin IX from exogenous 5‐aminolevulinic acid was preserved in the photooxidatively damaged plants, protochlorophyll and chlorophyll accumulation was no longer possible. It appears from our data that in higher plants the pathway of tetrapymole synthesis up to protoporphyrin IX is not adversely affected by a photooxidative treatment of the plastids that destroys the capacity of the organelle to synthesize chlorophyll.
SIMULTANEOUS MEASUREMENT OF PHOTOSYNTHETIC OXYGEN EVOLUTION AND CARBON DIOXIDE ASSIMILATION UNDER ANAEROBIOSIS
Authors: MacInnis J. M. , McDonald K. A. , Sigman M. E. , Greenbaum E. 
Published: January 2008

AbstractInstrumentation has been developed for measuring absolute simultaneous assimilation of carbon dioxide and evolution of oxygen by photosynthetic systems in anaerobic atmospheres under flow conditions. Time‐dependent photosynthetic quotients (PSQ) have bccn obtained. A detailed description of the instrument, including how it was constructed, calibrated and uscd for photosynthesis measurements, is presented. An important factor in the measurements was a clear understanding of the response time of the instrument. As with any flow system, flow rate, forward void volume and relative position of the O2 and CO2 sensors in the gas train were crucial to performance. Response time was measured by step‐function calibrations mimicking PSQ of unity. Oxygen was generated using an in‐line electrolysis cell driven by a programmable constant current source. Carbon dioxide assimilation was mimicked with the use of a programmable electronic gas blending system. Simultaneous step functions of these two key photosynthetic parameters fully characterized the response time and sensitivity of the instrument. In this report, time‐dependent PSQ for spinach leaf disks and the microalga Scenedesmus D3 are reported. It is explicitly demonstrated that the transient approach to steady state is different for the two systems. Whereas the time‐dependent PSQ for spinach depended on illumination history and reached a steady‐state value less than 1, this was not the case for Scenedesmus.
CHLOROPHYLEPHOTOSENSITIZED ELECTRON TRANSFER BETWEEN CYTOCHROME c AND A LIPID‐MODIFIED TRANSPARENT INDIUM OXIDE ELECTRODE
Authors: Salamon Z. , Tollin G. 
Published: January 2008

AbstractBoth direct and chlorophyll‐photosensitized electron transfer reactions between cytochrome c and a lipid‐modified indium oxide electrode have been studied by cyclic voltammetry and photoelectrochemistry. The lipid films consisted of egg phosphatidylcholine (PC), either alone or in combination with the negatively charged surfactant dihexadecylphosphate (DHP‐), and contained varying amounts of chlorophyll. The photocurrents were either ca‐thodic, when cytochrome c was used in its oxidized form in the supporting electrolyte, or anodic when the reduced form of cytochrome c was present, with a magnitude that depended on the PC concentration and the applied voltage. Quantum efficiencies of the anodic and cathodic photocurrents reached their maxima (5% and 10/o, respectively), at an intermediate PC concentration (5 mg/mL in the membrane‐forming solution), conditions under which the diffusion‐controlled electrochemical response of cytochrome c was also maximal. Incorporation of DHP‐ into the PC film increased both the direct and chlorophyll‐photosensitized currents, presumably due to electrostatic binding of the positively charged cytochrome c to the electrode surface.
RECONSTITUTION OF ALLOPHYCOCYANIN FROM Mastigocladus laminosus WITH ISOLATED LINKER POLYPEPTIDE
Authors: Gottschalk L. , Lottspeich F. , Scheer H. 
Published: January 2008

AbstractThe core linker polypeptide Lc8.9 was isolated from Mastigocladus laminosus and purified on a preparative scale. A method for the reconstitution of allophycocyanin (AP)—linker complexes from isolated polypeptides was developed. The complex (αAP(βAP)3 Lc8.9 was reconstituted and compared to (αAPβAP) and (αAPβAP)3 by sucrose density gradient ultracentrifugation, absorption, fluorescence emission and circular dichroism spectroscopy. Differences in the spectra of reconstituted and of directly isolated AP complexes are discussed.
ALTERATIONS OF PROTEOGLYCANS IN ULTRAVIOLET‐IRRADIATED SKIN
Authors: Margelin Dominique , Fourtanier Anny , Thevenin Thierry , Medaisko Chantal , Breton Monique , Picard Jacques 
Published: January 2008

Abstract— The effect of UVB exposure on the distribution and synthesis of dermal proteoglycans was measured in the skin of hairless mice. Two groups of mice were included: one was irradiated for 10 weeks; the other was kept as control. After intraperitoneal injection of sodium 35S‐sulfate, punch biopsies were taken for histology and proteoglycans were extracted from the remaining skin with 4 M guanidinium chloride, containing 3–[(3‐cholamidopropyl)dimethylammonio]‐1‐propanesulfonate (0.5%, weight per volume). Following proteolytic digestion, the glycosaminoglycan constituents were isolated and analyzed by quantitative cellulose acetate electrophoresis and enzymatic digestibility.Under the influence of UVB radiation, newly synthesized proteoglycans measured by 35SO4 uptake increased as much as 60%. In addition, the irradiated skin had a higher average content of proteoglycan than had control skin (4981 μg vs 4134 μg/g dry weight). This could be ascribed to an increase in heparin (1400 vs 533 μg/g dry weight) and heparan sulfate (472 vs 367 μg/g dry weight), whereas no change in the concentration of hyaluronic acid (1243 vs 1372 μg/g dry weight) and dermatan sulfate (1866 vs 1863 μg/g dry weight) was observed. The irradiated animals also exhibited a marked increase in the synthesis of heparan sulfate and heparin (62% and 71%, respectively). These results demonstrate that chronic doses of UVB altered proteoglycan metabolism through both quantitative and qualitative changes.