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991.
Ogishima T Mitani F Suematsu M 《The Journal of steroid biochemistry and molecular biology》2008,111(1-2):80-86
We have found cytochrome P-450(17alpha) in the islets of Langerhans of rat pancreas. Its existence coincided with that of insulin and demarcated those of glucagon and somatostatin, demonstrating the localization in beta-cells. The enzyme has not only 17alpha-hydroxylase activity but also lyase one, which is a prerequisite for androgen biosynthesis. The pancreatic microsomes converted progesterone mainly to androstenedione with a minor production of 17alpha-hydroxyprogesterone. Due to a low activity of the built-in lyase, cytochrome P-450(17alpha) requires a sufficient electron-transfer from P-450 reductase or presence of an activator to promote the C-C bond cleavage. In beta-cells, P-450 reductase was abundant and could efficiently transfer electrons to P-450(17alpha). Actually, inhibition with anti-P-450 reductase or limitation of NADPH preferentially reduced the lyase activity. Androstenedione was accumulated when its further metabolism was suppressed. We also found localization of cytochrome P-450scc and 3beta-hydroxysteroid dehydrogenase in beta-cells. These results indicate that the immediate substrate for androgen formation, progesterone, is intracellularly produced and is converted mainly to androstenedione with support by an efficient electron supply from P-450 reductase. The product was supposed to be further metabolized to the reduced derivatives such as testosterone, 5alpha-androstanedione, and dihydrotestosterone, which would act as local steroids in the islets of Langerhans. 相似文献
992.
Makoto Hayashi Eiichi Kamata Akihiko Hirose Mika Takahashi Takeshi Morita Makoto Ema 《Mutation Research - Genetic Toxicology and Environmental Mutagenesis》2005,588(2):129-135
Genotoxicity is one of the important endpoints for risk assessment of environmental chemicals. Many short-term assays to evaluate genotoxicity have been developed and some of them are being used routinely. Although these assays can generally be completed within a short period, their throughput is not sufficient to assess the huge number of chemicals, which exist in our living environment without information on their safety. We have evaluated three commercially available in silico systems, i.e., DEREK, MultiCASE, and ADMEWorks, to assess chemical genotoxicity. We applied these systems to the 703 chemicals that had been evaluated by the Salmonella/microsome assay from CGX database published by Kirkland et al. [1]. We also applied these systems to the 206 existing chemicals in Japan that were recently evaluated using the Salmonella/microsome assay under GLP compliance (ECJ database). Sensitivity (the proportion of the positive in Salmonella/microsome assay correctly identified by the in silico system), specificity (the proportion of the negative in Salmonella/microsome assay correctly identified) and concordance (the proportion of correct identifications of the positive and the negative in Salmonella/microsome assay) were increased when we combined the three in silico systems to make a final decision in mutagenicity, and accordingly we concluded that in silico evaluation could be optimized by combining the evaluations from different systems. We also investigated whether there was any correlation between the Salmonella/microsome assay result and the molecular weight of the chemicals: high molecular weight (>3000) chemicals tended to give negative results. We propose a decision tree to assess chemical genotoxicity using a combination of the three in silico systems after pre-selection according to their molecular weight. 相似文献
993.
Patricia E. Crane Yuichi Yamaoka Jintana Engkhaninun Makoto Kakishima 《Mycoscience》2005,46(3):143-147
A rust fungus found in Japan on Rhododendron kaempferi, R. kiusianum, and R. dauricum has previously been identified as Chrysomyxa rhododendri. Light and scanning electron microscopy of fresh and herbarium materials of the rust fungus, however, show that the spore surface morphology differs from the urediniospores of C. rhododendri, and the spores are slightly smaller. Furthermore, the DNA sequence of the 5′-end of the large subunit of ribosomal DNA differs from that of C. rhododendri by 3%. Telia have not been found; therefore, it is redescribed as a new anamorphic species, Caeoma tsukubaense. Several specimens from North Korea, Tibet, and Nepal bearing a similar rust fungus are also included in the species.Contribution no.193 from the Laboratory of Plant Parasitic Mycology, Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan 相似文献
994.
Makoto Sasaki Paul Jordan Tomas Welbourne Alireza Minagar Takashi Joh Makoto Itoh John W Elrod J Steven Alexander 《BMC physiology》2005,5(1):3
Background
Cytokine mediated induction of the mucosal addressin cell adhesion molecule-1(MAdCAM-1) expression is associated with the onset and progression of inflammatory bowel disease (IBD). 相似文献995.
Hiroki Inoue Tomoko Kudo Hiroshi Kamada Makoto Kimura Isamu Yamaguchi Hiroshi Hamamoto 《Plant Physiology and Biochemistry》2005,43(12):1089-1094
At concentrations greater than 0.1 mM, CuSO(4) provoked a rapid and sustained increase in the cytosolic free Ca(2+) concentration ([Ca(2+)](cyt)), in tobacco suspension culture cells expressing apoaequorin, a Ca(2+)-sensitive photoprotein. The increase was suppressed by treatment with LaCl(3), indicating that the increase is due to an influx of Ca(2+) from the apoplast through plasma membrane Ca(2+) channels. Although stimulation of H(2)O(2) production upon the CuSO(4) treatment (0.1 mM) was observed, treatment with catalase did not inhibit the increase in [Ca(2+)](cyt), and treatment with H(2)O(2) dose-dependently suppressed or delayed the increase. These results suggested that active oxygen species generated through copper-mediated reactions, or copper-mediated oxidative damages to plasma membrane, are not responsible for the increase. Treatment with sulfhydryl reagents, which alkylate or oxidize thiol groups, or acidification of the culture medium suppressed the increase in [Ca(2+)](cyt). These results demonstrated that copper causes an influx of Ca(2+) through plasma membrane Ca(2+) channels, and that plasma membrane thiol groups play an important role in activating the Ca(2+) channels. 相似文献
996.
We have developed a personal-computer-based water quality analysis system for river basins. The system estimates potential N outflow by model and calculates actual N outflow from monitoring data. For the former it uses the potential load factor method to estimate annual nitrogen load from various sources and runoff potential from each area of land in a basin. For the latter it analyzes water quality monitoring data in relation to meteorological data. We used the system to analyze N outflow in basins around Lake Kasumigaura and the Yahagi River in central Honshu, Japan. The land around Lake Kasumigaura is rather flat, and about 25% is periodically flooded for rice and lotus cultivation. The land around the Yahagi River is mountainous, and much less land is flooded. In the Yahagi River basin the actual N outflow agreed closely with the potential. However, the actual N outflow in the basin around Lake Kasumigaura was much less than the potential, suggesting that a large part of the N load is denitrified in flooded soils. This further indicates that a sequence of different land uses including flooded rice fields is an important factor determining N outflow in basins in Japan. On the basis of the above analyses, we incorporated a denitrification model into the system that enables us to estimate N balance in a designated basin; this system may be helpful in the formulation of scenarios of land use and soil management for improving water quality. 相似文献
997.
Gao Min-tian Makoto Hirata Michiteru Koide Hirokazu Takanashi Tadashi Hano 《Process Biochemistry》2004,39(12):1903-1907
An efficient process for producing l-lactic acid using an, EDF method is described. The results showed that intermittent EDF with continuous medium feed was the best one among the experiment methods employed. Comparing with the conventional EDF, intermittent EDF (seven on–off) with continuous medium feed indicated that the maximum value of o.d.660 was not increased, but productivity was 1.5 times higher. The yield increased by above 30% and glucose transport decreased to 1/10 (from 0.46 to 0.05). 相似文献
998.
We investigate the modulation of circumnutation in inflorescence stems of Arabidopsis to determine the circadian regulation of circumnutation. Under constant light conditions (LL), circumnutation speed in wild-type plants fluctuates, with the phase of the highest speed at subjective dawn; the period length is close to 24 h. toc1 appears to shorten the period and elf3 causes an arrhythmic phenotype in circumnutation speed in LL, suggesting that a common circadian clock may control both circumnutation speed and other circadian outputs. These results highlight for the first time a role for a circadian clock in the regulation of circumnutation based on genetic analysis of Arabidopsis. 相似文献
999.
17β-Hydroxysteroid dehydrogenase type 11 (17βHSD11) is mostly localized on the endoplasmic reticulum (ER) membrane under normal conditions and redistributes to lipid droplets (LDs) when the formation of LDs is induced. In this study, confocal microscopy analyses of the subcellular localization of the mutated 17βHSD11 proteins in cells with or without LDs revealed that both an N-terminal hydrophobic sequence and an adjacent sequence that has a weak homology with the PAT motif are independently necessary and both parts together (28 amino acid residues in total) are sufficient for the dual localization of 17βHSD11. Mutation analyses suggest that the PAT-like motif in 17βHSD11 will not be functionally similar to the canonical PAT motif. Hsp60 was identified as a possibly interacting protein with the PAT-like motif, and biochemical and microscopic analyses suggest that Hsp60 may be partly, but not necessarily involved in recognition of the PAT-like part of the targeting sequence of 17βHSD11. 相似文献
1000.
Kimura K Jin H Ogawa M Aoe T 《Biochemical and biophysical research communications》2008,366(4):1048-1053
Tubular-interstitial injury plays a key role in the progression of chronic kidney disease. Although endoplasmic reticulum (ER) stress plays significant roles in the development of chronic diseases such as neurodegenerative disease, cardiomyopathy and diabetes mellitus, its pathophysiological role in chronic renal tubular cell injury remains unknown. BiP is an essential chaperone molecule that helps with proper protein folding in the ER. Recently, we have produced a knock-in mouse that expresses a mutant-BiP in which the retrieval sequence to the ER is deleted in order to elucidate physiological processes that are sensitive to ER functions in adulthood. The heterozygous mutant-BiP mice showed significant tubular-interstitial lesions with aging. Furthermore, proteinuria induced by chronic protein overload accelerated the tubular-interstitial lesions in the mutant mice, accompanying caspase-12 activation and tubular cell apoptosis. These results suggest that the ER stress pathway is significantly involved in the pathophysiology of chronic renal tubular-interstitial injury in vivo. 相似文献