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81.
Previously we reported that fluorescent light (FL) illumination prior to UV irradiation (FL preillumination) had multiple effects on the repair of cyclobutane pyrim-idine dimers (CPD) and (6-4) photoproducts ([6-4] PD) in cultured goldfish cells (RBCF-1) at the exponentially growing phase. In this study, it is shown that even under the confluent condition of RBCF-1 cells, FL preillumination increased the disappearance of (6-4) PD in the dark. In addition, both at confluence and at the exponentially growing phase, the disappearance of (6-4) PD after PR treatment was increased by FL preillumination to RBCF-1 cells. Moreover, it was found that H2O2 pre-treatment, followed by UV irradiation, of the exponentially growing cells also enhanced the disappearance of (6-4) PD in the dark and by photorepair treatment. The degree of enhancement by H2O2 pretreatment was almost the same as that by FL preillumination. 相似文献
82.
Rüffer T Ohashi M Shima A Mizomoto H Kaneda Y Mashima K 《Journal of the American Chemical Society》2004,126(39):12244-12245
Reaction of Mo2(pyphos)4 (1) with [RhCl(CO)2]2 followed by treatment of excess amounts of tBuNC resulted in the clean formation of [Mo2Rh2(tBuNC)4(pyphos)4](X)2 (4a; X = Cl). The X-ray diffraction study as well as spectroscopic analyses of 4c (X = BPh4) implied that there is no direct sigma-bonding interaction between each Rh(I) atom and the Mo2 core. Each Rh(I) atom in 4 can be oxidized concurrently by 2 equiv of [Cp2Fe]PF6 to afford [Mo2Rh2(Cl)2(tBuNC)4(pyphos)4](PF6)2 (5) along with the formation of two Mo-Rh(II) single bonds and the reduction of the bond orders of the Mo-Mo moiety. 相似文献
83.
84.
Akihiro Shima Mituo Kenaga Osamu Nikaido Hiraku Takebe Nobuo Egami 《Photochemistry and photobiology》1981,33(3):313-316
Abstract— Cultured cells derived from a goldfish were irradiated with 254nm ultraviolet light. Cell survival and splitting of pyrimidine dimers after photoreactivation treatment with white fluorescent lamps were examined by colony forming ability and by a direct dimer assay, respectively. When UV-irradiated (5 J/m2 ) cells were illuminated by photoreactivating light, cell survival was enhanced up to a factor of 9 (40min) followed by a decline after prolonged exposures. Exposure of UV-irradiated (15 J/m2 ) cells to radiation from white fluorescent lamps reduced the amounts of thymine-containing dimers in a photoreactivating fluence dependent manner, up to about 60% reduction at 120 min exposure. Keeping UV-irradiated cells in the dark for up to 120min did not affect either cell survival or the amount of pyrimidine dimers in DNA, indicating that there were not detectable levels of a dark-repair system in the cells under our conditions. Correlation between photoreactivation of colony forming ability and photoreactivation of the pyrimidine dimers was demonstrated, at least at relatively low fluences of photoreactivating light. 相似文献
85.
Sebastian Schaupp Francisco J. Arriaza-Gallardo Dr. Nicole Paczia Kenichi Ataka Dr. Seigo Shima 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(6):e202316478
[Fe]-hydrogenase harbors the iron-guanylylpyridinol (FeGP) cofactor, in which the Fe(II) complex contains acyl-carbon, pyridinol-nitrogen, cysteine-thiolate and two CO as ligands. Irradiation with UV-A/blue light decomposes the FeGP cofactor to a 6-carboxymethyl-4-guanylyl-2-pyridone (GP) and other components. Previous in vitro biosynthesis experiments indicated that the acyl- and CO-ligands in the FeGP cofactor can scramble, but whether scrambling occurred during biosynthesis or photolysis was unclear. Here, we demonstrate that the [18O1-carboxy]-group of GP is incorporated into the FeGP cofactor by in vitro biosynthesis. MS/MS analysis of the 18O-labeled FeGP cofactor revealed that the produced [18O1]-acyl group is not exchanged with a CO ligand of the cofactor, indicating that the acyl and CO ligands are scrambled during photolysis rather than biosynthesis, which ruled out any biosynthesis mechanisms allowing acyl/CO ligands scrambling. Time-resolved infrared spectroscopy indicated that an acyl-Fe(CO)3 intermediate is formed during photolysis, in which scrambling of the CO and acyl ligands can occur. This finding also suggests that the light-excited FeGP cofactor has a higher affinity for external CO. These results contribute to our understanding of the biosynthesis and photosensitive properties of this unique H2-activating natural complex. 相似文献
86.
87.
K. Shima 《The European Physical Journal C - Particles and Fields》1999,7(2):341-345
By using the irreducible representation of N = 10 extended Super-Poincaré algebra, an attempt to interpret the quarks, the leptons and the gauge bosons except the graviton
as the composites of more fundamental objects with spin 1/2, superon quintet, is presented. All the local gauge interactions of GUTs are investigated systematically by using the superon diagrams. The
stability of the proton and the suppression of the flavour changing neutral currents are understood naturally in the superon
pictures of GUTs. The fundamental action of the model is proposed and the uniqueness of the model is pointed out.
Received: 5 June 1998 / Published online: 2 November 1998 相似文献
88.
89.
Jun‐ichi Kadokawa Shima Inomata Yasuhiro Iwasaki Hideyuki Tagaya Koji Chiba 《Macromolecular rapid communications》2000,21(17):1253-1256
This communication reports the group‐transfer polymerization of a cyclic trimethylsilyl dienolate, 2‐(trimethylsilyloxy)furan ( 1 ), initiated with benzaldehyde. The polymerization proceeded in the presence of a tetrabutylammonium salt as the catalyst in THF solvent at 0–50°C. The product was isolated as an ethyl acetate insoluble fraction after acidic work‐up. The structure of the product polymer was determined by means of 1H NMR, 13C NMR, and IR spectroscopy to be polylactone 3 . The mechanism of the polymerization can be explained by a Michael‐type addition of 1 onto the propagating end. 相似文献
90.