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Faruk Can, Seyda Korkut Ozoner, Pinar Ergenekon, Elif Erhan
This study describes the construction and characterization of an amperometric nitrate biosensor based on the Polypyrrole (PPy)/Carbon nanotubes (CNTs) film. Nitrate reductase (NR) was both entrapped into the growing PPy film and chemically immobilized via the carboxyl groups of CNTs to the CNT/PPy film electrode. The optimum amperometric response for nitrate was obtained in 0.1 M phosphate buffer solution (PBS), pH 7.5 including 0.1 M lithium chloride and 7 mM potassium ferricyanide with an applied potential of 0...
January 1, 2012: Materials Science & Engineering. C, Materials for Biological Applications
Nagwa Ibrahim Shehata, Hanan Mohamed Abd-Elgawad, Mohamed Nabil Mawsouf, Amira Abd-Elmonem Shaheen
Controlled ozone (O(3)) administration is known to promote oxidative preconditioning and, thus, may reverse chronic oxidative stress that accompanies aging. Therefore, the present work was undertaken to study the potential role of O(3) in ameliorating certain age-related biochemical changes represented by impaired activities of inner mitochondrial membrane enzymes, compromised energy production and increased oxidative burden in male rat cerebral cortex. Prophylactic administration of O(3)-O(2) mixture to 3 month-old rats, at an intrarectal dose of 0...
December 2012: Biogerontology
Hidetoshi Inada, Taisuke Kondo, Nahid Akhtar, Daiki Hoshino, Masahiro Yamaguchi, Takeshi Izuta
To clarify the relationship between cultivar difference in the sensitivity of net photosynthesis to ozone (O(3)) and the reactive oxygen species (ROS) scavenging system in wheat (Triticum aestivum), we investigated the effects of chronic exposure to ambient levels of O(3) on gas exchange rates, activity and concentration of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), activity of ROS scavenging enzymes and concentration of antioxidants of the flag leaf in two Japanese winter wheat cultivars (Norin 61 and Shirogane-komugi)...
October 2012: Physiologia Plantarum
D Möcker, D Hofmann, K Jung, J Bender, H J Weigel
Abstract Young wheat (C3) and maize (C4) plants were exposed to near-ambient concentrations of ozone in open-top chambers in order to investigate the possible effects of ozone on nitrogen metabolism. Nitrogen was supplied to the plants by adding (15)N-labelled tracer substances via the soil substrate. Enzyme activities (NADH nitrate reductase, nitrite reductase, glutamine synthetase and NADH glutamate dehydrogenase) and the incorporation of (15)N were determined. The findings show that nitrogen metabolism was affected by O(3), however, there were distinct differences between the two species...
August 1996: Isotopes in Environmental and Health Studies
Michael Puckette, Niranjani J Iyer, Yuhong Tang, Xin-Bin Dai, Patrick Zhao, Ramamurthy Mahalingam
Acute ozone is a model abiotic elicitor of oxidative stress and a useful tool for understanding biochemical and molecular events during oxidative signaling. Two Medicago truncatula accessions with contrasting responses to ozone were used to examine translational regulation during ozone stress. In ozone-resistant JE154, significant reduction in ribosome loading was observed within one hour of ozone treatment, suggesting energy homeostasis as a vital factor for oxidative stress management. Polysomal RNA-based expression profiling with Affymetrix arrays revealed extensive changes in the translatomes of both accessions...
January 2012: Molecular Plant
Nancy Chia, Luan Wang, Xiangyi Lu, Mary-Claude Senut, Carol Brenner, Douglas M Ruden
Many environmental toxins, such as heavy metals, air particles, and ozone, induce oxidative stress and decrease the levels of NADH and NADPH, cofactors that drive anabolic biochemical reactions and provide reducing capacity to combat oxidative stress. Recently, it was found that the Ten-eleven translocation (TET) protein family members, which oxidize 5-methylcytosine (5-mC) to 5-hydroxymethylcytosine (5-hmC) in the DNA, is activated under high oxygen conditions by alpha ketoglutarate (α-KG), a cofactor produced by aerobic metabolism in the citric acid cycle...
July 2011: Epigenetics: Official Journal of the DNA Methylation Society
Amin Elsadig Eltayeb, Naoyoshi Kawano, Ghazi Hamid Badawi, Hironori Kaminaka, Takeshi Sanekata, Toshiyuki Shibahara, Shinobu Inanaga, Kiyoshi Tanaka
Ascorbate (AsA) is a major antioxidant and free-radical scavenger in plants. Monodehydroascorbate reductase (MDAR; EC is crucial for AsA regeneration and essential for maintaining a reduced pool of AsA. To examine whether an overexpressed level of MDAR could minimize the deleterious effects of environmental stresses, we developed transgenic tobacco plants overexpressing Arabidopsis thaliana MDAR gene (AtMDAR1) in the cytosol. Incorporation of the transgene in the genome of tobacco plants was confirmed by PCR and Southern-blot analysis and its expression was confirmed by Northern- and Western-blot analyses...
April 2007: Planta
Niranjani Jambunathan, Ramamurthy Mahalingam
Maintenance of pyridine nucleotide homeostasis is vital for normal growth and development of plants and animals. We demonstrate that Arabidopsis Growth Factor Gene 1 (GFG1; At4g12720) encoding a nudix hydrolase, is an NADH pyrophosphatase and ADP-ribose pyrophosphatase. The affinity for NADH and ADP-ribose indicates that this enzyme could serve as a connection between sensing cellular redox changes and downstream signaling. GFG1 transcript levels were rapidly and transiently induced during both biotic stresses imposed by avirulent pathogens and abiotic stresses like ozone and osmoticum...
June 2006: Planta
Alfredo Guéra, Angeles Calatayud, Bartolomé Sabater, Eva Barreno
A possible implication of the plastid NADH-plastoquinone-oxidoreductase (Ndh) complex in the response against ozone-mediated oxidative stress in barley (Hordeum vulgare L.) leaves was investigated. After a 4 h treatment, exposure of barley seedlings to moderate ozone concentrations produced leaf-age-dependent increases in lipid peroxidation, peroxidase, and Ndh complex activities in the thylakoid membranes. A significant amount and activity of the Ndh complex were detected in mature barley leaves, but not in young barley leaves...
January 2005: Journal of Experimental Botany
Ho-Sung Yoon, Hyoshin Lee, In-Ae Lee, Ki-Yong Kim, Jinki Jo
In a majority of living organisms, a fundamental protection mechanism from reactive oxygen species is by the ascorbate-glutathione cycle in which an important antioxidant, ascorbate (vitamin C), is utilized to convert harmful H2O2 to H2O. Monodehydroascorbate reductase (MDHAR) maintains reduced pools of ascorbate by recycling the oxidized form of ascorbate. By screening a Brassica campestris cDNA library, we identified a B. campestris MDHAR cDNA (BcMdhar) which encodes a polypeptide of 434 amino acids possessing domains characteristic of FAD- and NAD(P)H-binding proteins...
October 4, 2004: Biochimica et Biophysica Acta
A Ranieri, A Castagna, J Pacini, B Baldan, A Mensuali Sodi, G F Soldatini
The present work set out to define the processes involved in the early O3-induced H2O2 accumulation in sunflower plants exposed to a single pulse of 150 ppb of O3 for 4 h. Hydrogen peroxide accumulation only occurred in the apoplast and this temporally coincided with the fumigation period. The inhibitor experiments suggested that both the plasma membrane-bound NAD(P)H oxidase complex and cell-wall NAD(P)H PODs contributed to H2O2 generation. To investigate the mechanisms responsible for O3-induced H2O2 accumulation further, both production and scavenging of H2O2 were investigated in the extracellular matrix after subcellular fractionation...
November 2003: Journal of Experimental Botany
Carl Nathan
No abstract text is available yet for this article.
December 13, 2002: Science
B L Godber, J J Doel, G P Sapkota, D R Blake, C R Stevens, R Eisenthal, R Harrison
Xanthine oxidase (XO) was shown to catalyze the reduction of nitrite to nitric oxide (NO), under anaerobic conditions, in the presence of either NADH or xanthine as reducing substrate. NO production was directly demonstrated by ozone chemiluminescence and showed stoichiometry of approximately 2:1 versus NADH depletion. With xanthine as reducing substrate, the kinetics of NO production were complicated by enzyme inactivation, resulting from NO-induced conversion of XO to its relatively inactive desulfo-form...
March 17, 2000: Journal of Biological Chemistry
J B Mudd, P J Dawson, S Tseng, F P Liu
Treatment of red cell ghosts with ozone inhibited both AChE (marking the outside of the membrane) and G3PDH (marking the inside of the membrane). There was no change in tryptophan fluorescence of the ghosts after the ozone treatment. Band 3 protein was isolated from the ozone-treated ghosts. The protein was digested with trypsin to obtain water soluble peptides from the cytoplasmic N-terminal tail and the interhelical loops. Fluorescent peptides included GWVIHPLGLR from the outer loop between helices 7 and 8, and peptide WMEAAR from the N-terminal cytoplasmic tail...
February 15, 1997: Archives of Biochemistry and Biophysics
M V Rao, G Paliyath, D P Ormrod
Earlier studies with Arabidopsis thaliana exposed to ultraviolet B (UV-B) and ozone (O3) have indicated the differential responses of superoxide dismutase and glutathione reductase. In this study, we have investigated whether A. thaliana genotype Landsberg erecta and its flavonoid-deficient mutant transparent testa (tt5) is capable of metabolizing UV-B- and O3-induced activated oxygen species by invoking similar antioxidant enzymes. UV-B exposure preferentially enhanced guaiacol-peroxidases, ascorbate peroxidase, and peroxidases specific to coniferyl alcohol and modified the substrate affinity of ascorbate peroxidase...
January 1996: Plant Physiology
J R Kanofsky, P D Sima
Several ozone-biomolecule reactions have previously been shown to generate singlet oxygen in high yields. For some of these ozone-biomolecule reactions, we now show that the apparent singlet-oxygen yields determined from measurements of 1270 nm chemiluminescence were artifactually elevated by production of gas-phase singlet oxygen. The gas-phase singlet oxygen results from the reaction of gas-phase ozone with biomolecules near the surface of the solution. Through the use of a flow system that excludes air from the reaction chamber, accurate singlet-oxygen yields can be obtained...
September 1993: Photochemistry and Photobiology
J R Kanofsky, P D Sima
Singlet oxygen chemiluminescence was measured from the reaction of ozone with several biological molecules using a two-phase system in which ozone gas flowed over aqueous solutions of various biological molecules. Most of the chemiluminescence came from singlet oxygen which had diffused back into the gas phase. The intensity of the singlet oxygen chemiluminescence was adequately described by a one-dimensional mathematical model of singlet oxygen quenching and diffusion for the reaction of ozone with ascorbic acid, reduced glutathione, oxidized glutathione, methionine and NADH...
July 1994: Archives of Biochemistry and Biophysics
Y Takahashi, T Miura
Male Jcl:Wistar rats were exposed continuously to either ozone (O3) or nitrogen dioxide (NO2) for 7 and 14 days to examine the effects of these gases on the xenobiotic metabolizing systems of lung microsomes. Exposure to 0.2 and 0.4 ppm O3 increased NADPH-cytochrome P-450 reductase activity and cytochrome P-450 as well as microsomal protein by the 14th day, whereas NADH-cytochrome b5 reductase was not affected. The most marked increase was observed in cytochrome P-450. In parallel to this increment, the activities of benzo(a)pyrene hydroxylase and 7-ethoxycoumarin O-deethylase of exposed animals increased significantly on the 7th and 14th days of exposure to 0...
August 1985: Toxicology Letters
Y Takahashi, T Miura
Male Wistar rats were exposed to 0.2 and 0.4 ppm O3 for 4, 8, and 12 weeks and to 0.1 and 0.2 ppm O3 for 4 weeks to examine the effects of prolonged exposure to O3 on the xenobiotic metabolizing systems in the lung. Exposures to 0.2 and 0.4 ppm O3 caused a significant increase in the NADPH-cytochrome P-450 reductase activity and cytochrome P-450 content in a dose-dependent manner during 4-12 weeks, whereas NADH-cytochrome b5 reductase was not altered. After 12 weeks of exposure to 0.4 ppm O3, NADPH-cytochrome P-450 reductase and cytochrome P-450 reached a maximum showing 138 (P less than 0...
April 1987: Environmental Research
P C Panus, J Shearer, B A Freeman
Preexposure of rats to sublethal levels of hyperoxia or ozone reduces morbidity and mortality when the animals are subsequently exposed to lethal levels of either oxidant stress. Lung homogenates and isolated type II pneumocytes from rats exposed to these oxidant stresses demonstrate enhanced antioxidant enzyme activities. Antioxidant enzymes, superoxide dismutase, catalase, and glutathione peroxidase are responsible for the detoxification of partially reduced oxygen species, superoxide and hydrogen peroxide, to less reactive states...
1988: Experimental Lung Research
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