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61.
Mitsuhiko Akaboshi Masato Noda Kenichi Kawai Hirotoshi Maki Keizo Kawamoto 《Origins of life and evolution of the biosphere》1979,9(3):181-186
Radical formation in9 0Y--irradiated D- and L-alanines was studied using ESR. It was observed that the relative radical concentration by -irradiation was distinguishably (13.9–21.5%) more in D-alanine than in L-alanine. Discussion was made on the possible mechanisms for the observed results. 相似文献
62.
- When applying the adsorption theory to the selectivity coefficient,K and Mg uptakes by cells in a K-Mg replacement series of mediaare not regulated only by a common mechanism, under the assumptionthat b values, which indicate the affinities between the ionand the adsorptive surface, do not change.
- Regulation of Kand Mg uptakes by a common multiphasic mechanismin the cellsis possible when the selectivity coefficient bK/bMgvaries inverselywith the MK/MMg ratio in the external medium.
- K and Mg uptakesare not regulated only by their respectivesingle specific mechanisms.
- Another possibility is regulation of K and Mg uptakes bothbycommon and specific mechanisms. The common mechanism maybemultiphasic.
63.
K. Higashi M. Kohno K. Nishinaga N. Hanasaki K. Shikichi Y. Takatsuka Y. Sakamoto 《Experimental cell research》1975,93(2):299-308
A procedure was developed for isolation of variously sized nucleoli in order to study the mechanism of nucleolar formation from multiple nucleolar organizers and to compare the compositions of different-sized nucleoli from Ehrlich ascites tumor cells. Relatively small nucleoli and large nucleoli from Ehrlich ascites tumor cells were separated by centrifugation at 400 g for 5 min in a layer of 0.34 M sucrose over 0.88 M sucrose. Small nucleoli remained in the 0.34 M sucrose layer while the large nucleoli accumulated in the 0.88 M sucrose.Three fractions, provisionally named small, intermediate and large nucleoli, containing 0.33, 0.41 and 0.84 pg DNA/nucleolus, respectively, were separated. Unfractionated nucleoli contained 0.59 pg DNA/nucleolus. The RNA content also increased with the size of the nucleolus and no significant difference was observed in the RNA/DNA ratios in the three fractions. Large nucleoli incorporated more [3H]uridine and [32P]orthophosphate into RNA than did small nucleoli, but the base compositions of the RNAs extracted from the different-sized nucleoli were similar. No significant fragmentation occurred on sonication of large nucleoli for 3 min, so the observed difference in the DNA contents was not due to mechanical damage of the nucleoli.The DNAs of these different-sized nucleoli were analysed on CsCl gradients. The nucleoli contained similar percentages of satellite DNA (20–22%) which were also similar to those of total, unfractionated nucleoli. Approx. 10% of the extranucleolar DNA is satellite DNA—thus the nucleolar fractions were probably not appreciably contaminated with extranucleolar DNA. The DNA of small nucleoli contained a slightly lower percentage (0.058%) of ribosomal cistrons than large nucleoli (0.081%). This means that the higher content of DNA in the large nucleoli is not merely due to longer sized chromatin with extra regions of the vicinity of nucleolar organizers. Thus these results suggest that the total content of ribosomal cistrons/nucleolus is roughly proportional to the DNA content of the nucleoli, at least in Ehrlich ascites tumor cells. Namely, the number of ribosomal cistrons per nucleolus for small, intermediate and large nucleoli is 40, 60 and 130, respectively. 相似文献
64.
Tetsuya Kawai Iwase Kazuhiko Noriko Takaya Yuko Yamaguchi Ryuta Kishii Yasushi Kohno Haruaki Kurasaki 《Bioorganic & medicinal chemistry letters》2017,27(4):1045-1049
We attempted to optimize sulfonamide-based non-alkyne LpxC inhibitors by focusing on improvements in enzyme inhibitory and antibacterial activity. It was discovered that inhibitors possessing 2-aryl benzofuran as a hydrophobe exhibited good activity. In particular, compound 21 displayed impressive antibacterial activity (E. coli MIC = 0.063 μg/mL, K. pneumoniae MIC = 0.5 μg/mL, and P. aeruginosa MIC = 0.5 μg/mL), and is a promising lead for further exploration as an antibacterial agent. 相似文献
65.
Hirotaka Shoji Hideo Hagihara Keizo Takao Satoko Hattori Tsuyoshi Miyakawa 《Journal of visualized experiments : JoVE》2012,(60)
Forced alternation and left-right discrimination tasks using the T-maze have been widely used to assess working and reference memory, respectively, in rodents. In our laboratory, we evaluated the two types of memory in more than 30 strains of genetically engineered mice using the automated version of this apparatus. Here, we present the modified T-maze apparatus operated by a computer with a video-tracking system and our protocols in a movie format. The T-maze apparatus consists of runways partitioned off by sliding doors that can automatically open downward, each with a start box, a T-shaped alley, two boxes with automatic pellet dispensers at one side of the box, and two L-shaped alleys. Each L-shaped alley is connected to the start box so that mice can return to the start box, which excludes the effects of experimenter handling on mouse behavior. This apparatus also has an advantage that in vivo microdialysis, in vivo electrophysiology, and optogenetics techniques can be performed during T-maze performance because the doors are designed to go down into the floor. In this movie article, we describe T-maze tasks using the automated apparatus and the T-maze performance of α-CaMKII+/- mice, which are reported to show working memory deficits in the eight-arm radial maze task. Our data indicated that α-CaMKII+/- mice showed a working memory deficit, but no impairment of reference memory, and are consistent with previous findings using the eight-arm radial maze task, which supports the validity of our protocol. In addition, our data indicate that mutants tended to exhibit reversal learning deficits, suggesting that α-CaMKII deficiency causes reduced behavioral flexibility. Thus, the T-maze test using the modified automatic apparatus is useful for assessing working and reference memory and behavioral flexibility in mice. 相似文献
66.
Chiho Nishizawa Keizo Takeshita Jun-ichi Ueda Michiko Mizuno Kazuo T. Suzuki Toshihiko Ozawa 《Free radical research》2013,47(4):385-392
Photosensitizers newly developed for photodynamic therapy of cancer need to be assessed using accurate methods of measuring reactive oxygen species (ROS). Little is known about the characteristics of the reaction of singlet oxygen (1O2) with spin traps, although this knowledge is necessary in electron spin resonance (ESR)/spin trapping. In the present study, we examined the effect of various reductants usually present in biological samples on the reaction of 1O2 with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). The ESR signal of the hydroxyl radical (?OH) adduct of DMPO (DMPO-OH) resulting from 1O2-dependent generation of ?OH strengthened remarkably in the presence of reduced glutathione (GSH), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), ascorbic acid, NADPH, etc. A similar increase was observed in the photosensitization of uroporphyrin (UP), rose bengal (RB) or methylene blue (MB). Use of 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO) as a spin trap significantly lessened the production of its ?OH adduct (DEPMPO-OH) in the presence of the reductants. The addition of DMPO to the DEPMPO-spin trapping system remarkably increased the signal intensity of DEPMPO-OH. DMPO-mediated generation of ?OH was also confirmed utilizing the hydroxylation of salicylic acid (SA). These results suggest that biological reductants enhance the ESR signal of DMPO-OH produced by DMPO-mediated generation of ?OH from 1O2, and that spin trap-mediated ?OH generation hardly occurs with DEPMPO. 相似文献
67.
Gaku Takibuchi Hirotake Imanishi Mami Morimoto Kaori Ishikawa Kazuto Nakada Noriko Toyama-Sorimachi Yoshiaki Kikkawa Keizo Takenaga Jun-Ichi Hayashi 《Mitochondrion》2013,13(6):881-887
To examine whether polymorphic mtDNA mutations that do not induce significant respiration defects regulate phenotypes of tumor cells, we used mouse transmitochondrial tumor cells (cybrids) with nuclear DNA from C57BL/6 (B6) strain and mtDNA from allogenic C3H strain. The results showed that polymorphic mutations of C3H mtDNA in the cybrids induced hypoxia sensitivity, resulting in a delay of tumor formation on their subcutaneous inoculation into B6 mice. Therefore, the effects of polymorphic mutations in normal mtDNA have to be carefully considered, particularly when we apply the gene therapy to the embryos to replace their pathogenic mtDNA by normal mtDNA. 相似文献
68.
Hideo Kohno Yu Chen Brian M. Kevany Eric Pearlman Masaru Miyagi Tadao Maeda Krzysztof Palczewski Akiko Maeda 《The Journal of biological chemistry》2013,288(21):15326-15341
Although several genetic and biochemical factors are associated with the pathogenesis of retinal degeneration, it has yet to be determined how these different impairments can cause similar degenerative phenotypes. Here, we report microglial/macrophage activation in both a Stargardt disease and age-related macular degeneration mouse model caused by delayed clearance of all-trans-retinal from the retina, and in a retinitis pigmentosa mouse model with impaired retinal pigment epithelium (RPE) phagocytosis. Mouse microglia displayed RPE cytotoxicity and increased production of inflammatory chemokines/cytokines, Ccl2, Il1b, and Tnf, after coincubation with ligands that activate innate immunity. Notably, phagocytosis of photoreceptor proteins increased the activation of microglia/macrophages and RPE cells isolated from model mice as well as wild-type mice. The mRNA levels of Tlr2 and Tlr4, which can recognize proteins as their ligands, were elevated in mice with retinal degeneration. Bone marrow-derived macrophages from Tlr4-deficient mice did not increase Ccl2 after coincubation with photoreceptor proteins. Tlr4−/−Abca4−/−Rdh8−/− mice displayed milder retinal degenerative phenotypes than Abca4−/−Rdh8−/− mice. Additionally, inactivation of microglia/macrophages by pharmacological approaches attenuated mouse retinal degeneration. This study demonstrates an important contribution of TLR4-mediated microglial activation by endogenous photoreceptor proteins in retinal inflammation that aggravates retinal cell death. This pathway is likely to represent an underlying common pathology in degenerative retinal disorders. 相似文献
69.
Carbon dynamics during litter decomposition have been described in a variety of forest ecosystems and provided insights into carbon flow in soils. To quantitatively assess how decomposition processes vary between litter types, solid-state 13C cross-polarization and magic-angle spinning nuclear magnetic resonance (CPMAS NMR) technique was applied to analyze conifer (cedar, cypress) and hardwood (chinquapin, beech, oak, birch) litter which had degraded during a 3 year litterbag experiment throughout Japan. The results were used to identify compositional changes and estimate decomposition constants (k values) in exponential equations. Total litter and carbon type mass losses during decomposition varied significantly between litter types, being affected by the initial physicochemical litter quality. Concomitant increases and decreases in carbonyl and O/N-alkyl C compositions, respectively, were observed for all litter types, but aromatic and aliphatic C dynamics were less consistent. In hardwoods, [aromatic/aliphatic C ratio] was generally stable during decomposition, suggesting that, in hardwoods, the decomposabilities of aromatic and aliphatic C were similar. In the conifers, an increasing [aromatic/aliphatic C ratio] during decomposition suggested that aromatic C was more recalcitrant than aliphatic C. These results suggest that different decomposition processes between litter types might be related to different aromatic and aliphatic C behaviors, as affected by lignin stability and lipid leachability and biosynthesis. Variations in the k values for total litter and carbon types were not obvious between litter types, although the mass loss patterns differed significantly. The k values estimated in this study may contribute to predictions of soil carbon dynamics and the validation of carbon compartment models in forest ecosystems. 相似文献
70.
Hiroshi Kadokura Michiko Saito Akio Tsuru Akira Hosoda Takao Iwawaki Kenji Inaba Kenji Kohno 《Biochemical and biophysical research communications》2013
ERdj5 (also known as JPDI) is a member of PDI family conserved in higher eukaryotes. This protein possesses an N-terminal J domain and C-terminal four thioredoxin domains each having a redox active site motif. Despite the insights obtained at the cellular level on ERdj5, the role of this protein in vivo is still unclear. Here, we present a simple method to purify and identify the disulfide-linked complexes of this protein efficiently from a mouse tissue. By combining acid quenching and thiol-alkylation, we identified a number of potential redox partners of ERdj5 from the mouse epididymis. Further, we show that ERdj5 indeed interacted with two of the identified proteins via formation of intermolecular disulfide bond. Thus, this approach enabled us to detect and identify redox partners of a PDI family member from an animal tissue. 相似文献