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The oxidation level of P700 induced by far-red light (DeltaA(FR)) in briefly dark-treated leaves of some sun plants decreased during the daytime and recovered at night. The dark recovery of decreased DeltaA(FR) proceeded slowly, with a half-time of about 5 h. We propose that stromal over-reduction induced by sunlight was the direct cause of the depression of DeltaA(FR). The depression of DeltaA(FR) found during the daytime was reproduced by controlled illumination with saturating light of fully dark-treated leaves. Simultaneous measurement of P700 redox and chlorophyll fluorescence showed that the depression of DeltaA(FR) was associated with dark reduction of the plastoquinone pool, which represented cyclic electron transport activity. The decrease of DeltaA(FR) in the light-stressed chloroplasts was partly reversed by treatment with 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, an inhibitor of electron transport at the cytochrome b6/f complex, and the subsequent addition of methyl viologen, an efficient electron acceptor from photosystem I (PSI), stimulated further recovery, showing that both cyclic electron flow around PSI and the charge recombination within PSI were responsible for the light-induced depression of DeltaA(FR). The dark level of blue-green fluorescence, an indicator of NAD(P)H concentration, from intact chloroplasts was increased by high-light stress, suggesting that NADPH accumulated in stroma as a result of the high-light treatment. Possible effects on photosynthetic activity of over-reduction and its physiological relevance are discussed. 相似文献
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Omura F Fujita A Miyajima K Fukui N 《Bioscience, biotechnology, and biochemistry》2005,69(6):1162-1171
The Saccharomyces cerevisiae Put4 permease is significant for the transport of proline, alanine, and glycine. Put4p downregulation is counteracted by npi1 mutation that affects the cellular ubiquitination function. Here we describe mutant Put4 permeases, in which up to nine lysine residues in the cytoplasmic N-terminal domain have been replaced by arginine. The steady-state protein level of the mutant permease Put4-20p (Lys9, Lys34, Lys35, Lys60, Lys68, Lys71, Lys93, Lys105, Lys107 --> Arg) was largely higher compared to that of the wild-type Put4p, indicating that the N-terminal lysines can undergo ubiquitination and the subsequent degradation steps. Proline is the only amino acid that yeast assimilates with difficulty under standard brewing conditions. A lager yeast strain provided with Put4-20p was able to assimilate proline efficiently during beer fermentations. These results suggest possible industrial applications of the mutant Put4 permeases in improved fermentation systems for beer and other alcoholic beverages based on proline-rich fermentable sources. 相似文献
84.
Eguchi J Kuwashima N Hatano M Nishimura F Dusak JE Storkus WJ Okada H 《Journal of immunology (Baltimore, Md. : 1950)》2005,174(11):7194-7201
We previously demonstrated that IL-4 gene-transfected glioma cell vaccines induce effective therapeutic immunity in preclinical glioma models, and have initiated phase I trials of these vaccines in patients with malignant gliomas. To gain additional mechanistic insight into the efficacy of this approach, we have treated mice bearing the MCA205 (H-2(b)) or CMS-4 (H-2(d)) sarcomas. IL-12/23 p40(-/-) and IFN-gamma(-/-) mice, which were able to reject the initial inoculation of IL-4 expressing tumors, failed to mount a sustained systemic response against parental (nontransfected) tumor cells. Paracrine production of IL-4 in vaccine sites promoted the accumulation and maturation of IL-12p70-secreting tumor-infiltrating dendritic cells (TIDCs). Adoptive transfer of TIDCs isolated from vaccinated wild-type, but not IL-12/23 p40(-/-), mice were capable of promoting tumor-specific CTL responses in syngeneic recipient animals. Interestingly, both STAT4(-/-) and STAT6(-/-) mice failed to reject IL-4-transfected tumors in concert with the reduced capacity of TIDCs to produce IL-12p70 and to promote specific antitumor CTL reactivity. These results suggest that vaccines consisting of tumor cells engineered to produce the type 2 cytokine, IL-4, critically depend on type 1 immunity for their observed therapeutic efficacy. 相似文献
85.
Yagi N Shimizu J Mohri S Araki J Nakamura K Okuyama H Toyota H Morimoto T Morizane Y Kurusu M Miura T Hashimoto K Tsujioka K Suga H Kajiya F 《Biophysical journal》2004,86(4):2286-2294
We studied x-ray diffraction from the left ventricular wall of an excised, perfused whole heart of a rat using x rays from the third-generation synchrotron radiation facility, SPring-8. With the beam at right angles to the long axis of the left ventricle, well-oriented, strong equatorial reflections were observed from the epicardium surface. The reflections became vertically split arcs when the beam passed through myocardium deeper in the wall, and rings were observed when the beam passed into the inner myocardium of the wall. These diffraction patterns were explained by employing a layered-spiral model of the arrangement of muscle fibers in the heart. In a quiescent heart with an expanded left ventricle, the muscle fibers at the epicardium surface were found to have a (1,0) lattice spacing smaller than in the rest of the wall. The intensity ratio of the (1,0) and (1,1) equatorial reflections decreased on contraction with a similar time course in all parts of the wall. The results show that it is possible to assign the origin of reflections in a diffraction diagram from a whole heart. This study offers a basis for interpretation of x-ray diffraction from a beating heart under physiologically and pathologically different conditions. 相似文献
86.
We investigated signal transduction between receptor-operated Ca(2+) influx (ROCI) and Src-related nonreceptor protein tyrosine kinase (PTK) in rat pancreatic acini. CCK and the Ca(2+) ionophore enhanced the Src-related PTK activity, whereas the high-affinity CCK-A receptor agonists, fibroblast growth factor (FGF), and the protein kinase C (PKC) activator had no or little effect. This increase was abolished by eliminating [Ca(2+)](o), loading of the intracellular Ca(2+) chelator, and administering the PTK inhibitor genistein. While genistein inhibited extracellular Ca(2+) or Mn(2+) entry induced by CCK and carbachol, it did not affect intracellular Ca(2+) release and oscillations. CCK dose-dependently increased the Src phosphotransferase activity, which was abolished by inhibitors of G(q) protein, phospholipase C (PLC), and Src, but not by the calmodulin kinase (CaMK) inhibitor. Intensities of the Src band and amounts of tyrosine phosphorylated Src were enhanced by CCK stimulation. Thus, Src cascades appear to be coupled to the low-affinity CCK-A receptor and utilize G(q)-PLC pathways for their activation, independent of PKC and CaMK cascades. The low-affinity CCK-A receptor regulates ROCI via mediation of Src-related PTK and activates Src pathways to cause [Ca(2+)](o)-dependent pancreatic exocytosis. 相似文献
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Kawasaki N Tanei S Ogata F Burapadaja S Loetkham C Nakamura T Tanada S 《Journal of physiological anthropology》2006,25(6):377-382
The number of cellular phone subscribers is increasing every year and there have been reports of health disorders related to the high-frequency radio waves. This paper considers the dependence of Thai university and high school students on cellular phones. A survey form (cellular phone dependence questionnaire: CPDQ) was distributed to 181 female and 177 male Thai university students and to 240 female and 140 male Thai high school students. The surveys were collected, Cronbach alpha coefficient was calculated, and a factor analysis was performed using the principal factor method and varimax rotation. The total scores were 16.54 to 20.04 and the Cronbach's alpha coefficients were 0.808 to 0.930. According to a factor analysis of 20 scored items, 4 factors were extracted for both male and female high school students, and the cumulative correlation coefficients of the male and female groups were 64.85% and 62.70%, respectively. Five factors were extracted for male university students and 6 factors were extracted for female university students, and the cumulative correlation coefficients were 58.08% and 57.91%, respectively. The W value results of the Shapiro-Wilk W-test for male university students, female university students, male high school students and female high school students were 0.969, 0.984, 0.964, and 0.913 respectively, thus verifying the normality of the score distributions.The total scores for the Thai university students were higher than the scores for the Thai high school students. The factor analysis of female high school students confirmed a large difference compared to male university students, male high school students, and Japanese female university students. (The Japanese students were surveyed in an earlier study by Toda et al.). Also, the CPDQ total score was high, which indicated a strong tendency toward dependence. 相似文献