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141.
An iron-containing superoxide dismutase (SOD, EC 1.15.1.1) was fully characterized from leaves of the higher plant Citrus limonum R. cv. Verna. This enzyme is the first iron-containing SOD to be characterized in the plant family Rutaceae . The purified Fe-SOD has a molecular mass of about 47 kDa and is composed of two non-covalently joined equal subunits. The amino acid composition determined for the enzyme was compared with that of a wide range of SODs and had highest degree of homology with the Fe-SODs from Brassica campestris and Nuphar luteum . The enzyme was more labile at high temperatures than some eucaryotic and procaryotic Fe-SODs. It showed a maximum stability at pH 7.8. The sensitivity of the enzyme to cyanide, hydrogen peroxide and o -phenanthroline was similar to those reported for other Fe-SODs. but the lemon enzyme was comparatively resistant to H2 O2 . By kinetic competition experiments, the rate constant for the disproportionation of superoxide radicals by lemon Fe-SOD was found to be 1.9 × 109 M −1 s−1 at pH 7.8 and 25°C. A comparative study between the molecular properties of this higher plant Fe-SOD and SODs from different origins is presented. 相似文献
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143.
Lee DF Su J Ang YS Carvajal-Vergara X Mulero-Navarro S Pereira CF Gingold J Wang HL Zhao R Sevilla A Darr H Williamson AJ Chang B Niu X Aguilo F Flores ER Sher YP Hung MC Whetton AD Gelb BD Moore KA Snoeck HW Ma'ayan A Schaniel C Lemischka IR 《Cell Stem Cell》2012,11(2):179-194
Many signals must be integrated to maintain self-renewal and pluripotency in embryonic stem cells (ESCs) and to enable induced pluripotent stem cell (iPSC) reprogramming. However, the exact molecular regulatory mechanisms remain elusive. To unravel the essential internal and external signals required for sustaining the ESC state, we conducted a short hairpin (sh) RNA screen of 104 ESC-associated phosphoregulators. Depletion of one such molecule, aurora kinase A?(Aurka), resulted in compromised self-renewal and consequent differentiation. By integrating global gene expression and computational analyses, we discovered that loss of Aurka leads to upregulated p53 activity?that triggers ESC differentiation. Specifically, Aurka regulates pluripotency through phosphorylation-mediated inhibition of p53-directed ectodermal and mesodermal gene expression. Phosphorylation of p53 not only impairs p53-induced ESC differentiation but also p53-mediated suppression of iPSC reprogramming. Our studies demonstrate an essential role for Aurka-p53 signaling in the regulation of self-renewal, differentiation, and somatic cell reprogramming. 相似文献
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145.
Gorka Erice Alvaro Sanz-Sáez Ricardo Aroca Juan Manuel Ruíz-Lozano Jean-Christophe Avice Juan José Irigoyen Manuel Sanchez-Diaz Iker Aranjuelo 《Acta Physiologiae Plantarum》2014,36(10):2607-2617
Although responsiveness of N2-fixing plants to elevated CO2 conditions have been analyzed in previous studies, important uncertainties remain in relation to the effect enhanced CO2 in nodule proteomic profile and its implication in leaf responsiveness. The aim of our study was to deepen our understanding of the relationship between leaf and nodule metabolism of N2-fixing alfalfa plants after long-term exposure to elevated CO2. After 30-day exposure to elevated CO2, plants showed photosynthetic down-regulation with reductions in the light-saturated rate of CO2 assimilation (A sat) and the maximum rate of rubisco carboxylation (Vcmax). Under elevated CO2 conditions, the rubisco availability limited potential photosynthesis by around 12 %, which represented the majority of the observed fall in Vcmax. Photosynthetic down-regulation has been associated with decreased N availability even if those plants are capable to assimilate N2. Diminishment in shoot N demand (as reflected by the lower rubisco and leaf N content) suggests that the lower aboveground N requirements affected negatively nodule performance. In this condition, specific nodule activity was reduced due to an effect on nodule metabolism that manifested as a lower amount of nitrogenase reductase. Moreover, the nodule proteomic approach also revealed that nodule functioning was altered simultaneously in various enzyme quantity apart from nitrogenase. At elevated CO2, the tricarboxylic acid cycle was also altered with a reduced amount of isocitrate synthase protein. The nodule proteome analysis also revealed the relaxation of the antioxidant system as shown by a decline in the amount of catalase and isoflavone reductase protein. 相似文献
146.
Daniela Gerovska Patricia García-Gallastegi Jean Descarpentrie Olatz Crende María Casado-Andrés Ander Martín Jokin Eguia Abdel-Majid Khatib Marcos J. Araúzo-Bravo Iker Badiola 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2021,1868(3):118912
Despite continuous exertion made, colon cancer still represents a major health problem and its incidence continues being high worldwide. There is growing evidence in support of the cancer stem cells (CSCs) being central in the initiation of this cancer, and CSCs have been the focus of various studies for the identification of new ways of treatment. Lately, the proprotein convertases (PCs) were reported to regulate the maturation and expression of various molecules involved in the malignant phenotype of colon cancer cells, however, the identity of the molecules regulated by these serine proteases in CSCs is unknown. In this study, we used the general PCs inhibitor, the Decanoyl-RVKR-chloromethylketone (Decanoyl-RVKR-CMK) that inhibits all the PCs found in the secretory pathway, and analyzed its effect on CSCs using RNA-seq analysis. Remarkably, from the only 9 up-regulated genes in the human SW620-derived sphere-forming cells, we identified 7 of the 11 human metallothioneins, all of them localized on chromosome 16, and zinc related proteins as downstream effectors of the PCs. The importance of these molecules in the regulation of cell proliferation, differentiation and chemoresistance, and their reported potential tumor suppressor role and loss in colon cancer patients associated with worse prognosis, suggests that targeting PCs in the control of the malignant phenotype of CSCs is a new potential therapeutic strategy in colon cancer. 相似文献
147.
Solar Cells: Corrugation Architecture Enabled Ultraflexible Wafer‐Scale High‐Efficiency Monocrystalline Silicon Solar Cell (Adv. Energy Mater. 12/2018)
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148.
E. Molina Grima J. A. Sánchez Pérez F. García Camacho J. L. García Sánchez J. M. Fernández Sevilla 《Journal of applied phycology》1995,7(2):129-134
Outdoor chemostat cultures of the marine microalgaIsochrysis galbana at constant dilution rate (0.034 h–1 ) have been carried out under different weather conditions. Steady-state biomass concentrations were 1.61±0.03 kg m–3 in May and 0.95±0.04 kg m–3 in July, resulting in biomass output rates of 0.54 kg m–3 d–1 and 0.32 kg m–3 d–1 in May and July, respectively. Two patterns of daily variation with the solar cycle were observed in the fatty acid content. Saturated and mono-unsaturated fatty acids (16:0 and 16:1n7) show significant variation with the solar cycle, associated with short-term changes in environmental factors. Palmitic and palmitoleic acids are generated during daylight and consumed during the dark period. However, polyunsaturated fatty acids do not show a significant response to the solar cycle and their changes are associated with long-term variation in environmental factors. The maximum EPA productivity was obtained in May, 14.1 g m–3 d–1, which is close to that found in the literature for indoor continuous cultures. Nonetheless, the outdoor EPA content (up to 2.61 % d.wt) was lower than the indoor EPA content from a previous study (5% d.wt). 相似文献
149.
The effects of some alcohols on the morphology ofAureobasidium pullulans were studied. The transition from yeast-like cells to mycelia was induced by ethanol and methanol. We studied the kinetics of the transition induced by ethanol. Yeast-like cells became progressively enlarged and, after four days, germ tubes were apparent, giving rise, eventually, to adult mycelia. The germ tubes arose in the absence of glucose, but not as a result of glucose starvation. 相似文献
150.
In Vitro Formation of Nitrate Reductase Using Extracts of the Nitrate Reductase Mutant of Neurospora crassa, nit-1, and Rhodospirillum rubrum 总被引:8,自引:4,他引:4
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In vitro formation of reduced nicotinamide adenine dinucleotide phosphate (NADPH)-nitrate reductase (NADPH: nitrate oxido-reductase, EC 1.6.6.2) has been attained by using extracts of the nitrate reductase mutant of Neurospora crassa, nit-1, and extracts of either photosynthetically or heterotrophically grown Rhodospirillum rubrum, which contribute the constitutive component. The in vitro formation of NADPH-nitrate reductase is characterized by the conversion of the flavin adenine dinucleotide (FAD) stimulated NADPH-cytochrome c reductase, contributed by the N. crassa nit-1 extract from a slower sedimenting form (4.5S) to a faster sedimenting form (7.8S). The 7.8S NADPH-cytochrome c reductase peak coincides in sucrose density gradient profiles with the NADPH-nitrate reductase, FADH(2)-nitrate reductase and reduced methyl viologen (MVH)-nitrate reductase activities which are also formed in vitro. The constitutive component from R. rubrum is soluble (both in heterotrophically and photosynthetically grown cells), is stimulated by the addition of 10(-4) M Na(2)MoO(4) and 10(-2) M NaNO(3) to cell-free preparations, and has variable activity over the pH range from 3.0 to 9.5. The activity of the constitutive component in some extracts showed a threefold stimulation when the pH was lowered from 6.5 to 4.0. The constitutive activity appears to be associated with a large molecular weight component which sediments as a single peak in sucrose density gradients. However, the constitutive component from R. rubrum is dialyzable and is insensitive to trypsin and protease. These results demonstrate that R. rubrum contains the constitutive component and suggests that it is a low molecular weight, trypsin- and protease-insensitive factor which participates in the in vitro formation of NADPH nitrate reductase. 相似文献