Abstract  Nitric oxide (NO) exerts multiple biologic roles in animal cells through differential regulation of three distinct forms of NO synthase encoded by separate genes. Macrophage-inducible nitric oxide synthase (iNOS) has been correlated with inhibition of viral growth, but little is known about the mechanism of this effect. To study the antiviral role of NO, we have generated a vaccinia virus (VV) recombinant expressing iNOS under the control of Escherichia coli LacI operator/repressor elements. When cultured cells of various origins are infected with this recombinant virus, there is inducible expression of iNOS in the presence of isopropylthio-beta-galactoside, as determined by Western blot and by detection of nitrite, a NO oxidation product. The levels of nitrite increase with time after infection, correlating with marked inhibition of VV DNA and late protein synthesis. Expression of VV early proteins is not affected by NO. Inhibition of VV DNA synthesis is likely to be in part a consequence of NO-mediated inhibition of viral ribonucleotide reductase, as this inhibition can be partially overcome by addition of deoxyribonucleosides. Inhibition of the essential viral functions by NO results in a reduction of virus yields by 50 to 90%, depending on the cell line. Thus, our results demonstrate a direct antiviral effect of NO, with inhibition of VV replication occurring at the level of DNA synthesis.

Abstract  To characterize the influence of nitric oxide (NO) donors on the intestinal absorption of macromolecules, the relationship between the release rate of NO from NO donors and their absorption-enhancing effects and the effects of several scavengers and generators on the absorption-enhancing effects of NO donor were investigated. The t1/2 values of the NO release rate from 3-(2-hydroxy-1-methylethyl-2-nitrosohydrazino)-1-propanamine (NOC5), 3-(2-hydroxy-1-methylethyl-2-nitrosohydrazino)-N-methyl-1-propanamine (NOC7) and N-ethyl-2-(1-ethyl-hydroxy-2-nitrosohydrazino)-ethanamine (NOC12) are 25, 5 and 100min, respectively. The absorption-enhancing effects of NO donors on the absorption of fluorescein isothiocyanate dextrans with an average molecular weight of 4400 (FD-4) are NOC5 > NOC7 > NOC12 in the colon. The lowest enhancing effect of NOC12 may be due to the slow rate of NO release. The enhancing effect of NOC7 rapidly disappeared compared with the effect of NOC5. The results raise the possibility that the difference between NOC5 and NOC7 on enhancing effect is related to the t1/2 of the NO release. The NOC7-induced enhancing effect was prevented by the co-administration of 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazole-1-oxyl-3-oxide sodium salt (C-PTIO), an NO scavenger; tiron, an O2(-) scavenger; mannitol, an OH* scavenger, and deferoxamine, peroxynitrate scavenger. Pyrogallol, an O2(-) generator, potentiated the NOC7-induced enhancing effect. These results support a role for peroxynitrate, and possibly OH*, in the NO donor-induced intestinal enhancing effect.

Abstract  A series of isopropyl fatty esters having different chain length (C(13)-C(23)) were synthesized and formulated in lipid nanoparticles based on Precirol ATO to evaluate their effect on the physicochemical properties of these latter. Moreover, drug loading and skin permeation of Econazole nitrate, chosen as a lipophilic model drug, were evaluated as well. The obtained nanosystems, prepared by high shear homogenization method, had a mean diameter ranging from 180 to 280 nm and showed an encapsulation efficiency of about 100%. Ex vivo permeation results demonstrated a parabolic correlation between permeation effect and chain length of the fatty esters present in the lipid nanoparticles formulated in hydrophilic gels. The maximum flux of drug was observed for the nanoparticles containing esters with 17 and 19 carbon atoms, suggesting that these formulations may constitute a potential carrier for topical delivery of econazole nitrate.

Abstract  Clenbuterol has been determined in urine by solid-phase extraction on a C-18 cartridge, diazotization of the eluate with nitrite, coupling of the diazonium ion with 1-(naphthyl)ethylenediamine, and separation of the azo dye formed by HPLC with a C-18 column and a micellar mobile phase containing 0.1 M sodium dodecyl sulphate, 12% n-butanol and 0.05 M citrate buffer, pH 3. Recoveries higher than 90% were obtained by mixing the samples with a 20% 0.2 M NaOH before extraction. Limits of detection of 51 and 6.7 ng L(-1) were obtained with spectrophotometric and thermal lens spectrometric detection, respectively; respective repeatabilities were 3.1% (5 mu g mL(-1)) and 5.6% (0.16 mu g mL(-1)).

Abstract  The Meerwein-Ponndorf-Verley (MPV) reaction of cyclohexanone with isopropyl alcohol, which yields cyclohexanol, was studied by using basic catalysts consisting of magnesium oxide. The oxides were prepared using various synthetic procedures including calcination of commercially available magnesium hydroxide and carbonate, calcination of magnesium hydroxides obtained from magnesium nitrate and sulphate, the sol-gel technique and precipitation by decomposition of urea. The solids thus obtained were characterized structurally by X-ray diffraction spectroscopy and their surface properties determined using gas adsorption measurements (of nitrogen for textural properties and carbon dioxide for basic properties). Based on the results, the most active catalyst was the solid prepared by rehydration and subsequent calcination of a magnesium oxide that was previously obtained from commercially available magnesium hydroxide. (C) 2003 Elsevier Science B.V. All rights reserved.

Abstract  The simpler non-supercritical drying approach has been used for the first time for the preparation of silica-silica composite aerogels (CA) and the efficiency of the process being demonstrated by testing the use of the aerogels for simulated high level nuclear waste confinement. Compositions of 5, 10, 20, 30, 40 and 50 wt% of silica (aerosil(R) 380) in silica-aerogel were prepared by introducing pyrogenic silica in to silica sol derived by hydrolysis of Tetraethoxy silane (TEOS). The silica-silica composite aerogels (CA) possessed very high surface area and low bulk densities. The effectiveness of the prepared composite aerogels as precursor for high level nuclear waste immobilized glass is also presented. Neodymium nitrate dissolved in isopropanol is used to simulate +3 valent actinides. The stability of neodymium in the glass matrix has been found to be extremely high. Transmission electron microscopy (TEM) has been used to characterise the aerogels as well as neodymium incorporated sintered gels. X-ray diffraction (XRD) studies of the sintered samples reveal the formation of neodymium silicates.

Abstract  The dynamics of the protic ionic liquid monomethylammonium nitrate is investigated by Car-Parrinello molecular dynamics simulations. On average, 1.8 of 3 possible hydrogen bond contacts are formed. Therefore, one hydrogen bond acceptor and one donor site in each ion pair of monomethylammonium nitrate remains free, which is similar to water. Furthermore, like water, monomethylammonium nitrate exhibits a fast fluctuating hydrogen bond network. The comparable hydrogen bond network and dynamics of both liquids might explain the similar impact on reactivity and selectivity found for chemical reactions. However, the hydrogen bond network of monomethylammonium nitrate and water show some structural differences. While the hydrogen bonds in water arrange in parallel fashion, the hydrogen bonds of monomethylammonium nitrate prefer angles of 0 degrees, 90 degrees, and 180 degrees. The ion dynamics of monomethylammonium nitrate indicate that at about 85% of the ion pairs are still connected after 14.5 ps. A closer inspection of the first solvation shell dynamics of one cation reveals that after 11 ps the current ion pair conformation is independent of the initial ion pair conformation because the ion pairs lose their information of the initial ion pair conformation much faster than the time needed to escape from their solvent cage. The ion dynamics of monomethylammonium nitrate can be described by the following model: There are ions rattling in long living cages which are formed by long living ion pairs.

Abstract  Kinetics and products of the interaction of HONO with solid films of Al2O3 were investigated under dark and UV irradiation conditions using a low pressure flow reactor (1-10 Torr) combined with a modulated molecular beam mass spectrometer for monitoring of the gaseous species involved. The reactive uptake of HONO to Al2O3 was studied as a function of HONO concentration ([HONO](0)=(0.6-3.5) x 10(12) molecule cm(-3)), relative humidity (RH=1.4 x 10(-4) to 35.4%), temperature (T=275-320 K) and UV irradiation intensity (J(NO2)=0.002-0.012s(-1)). The measured reactive uptake coefficient was independent of the HONO concentration and temperature. In contrast, the relative humidity (RH) was found to have a strong impact on the uptake coefficient: gamma=4.8 x 10(-6) (RH)(-6.61) and gamma=1.7 x 10(-5) (RH)(-0.44) under dark conditions and on irradiated surface (J(NO2)=0.012 s(-1)), respectively (gamma calculated with BET surface area, 30% conservative uncertainty). NO2 and NO were observed as products of the HONO reaction with Al2O3 surface with yields of 40 +/- 6 and 60 +/- 9%, respectively, independent of relative humidity, temperature, concentration of HONO and UV irradiation intensity under experimental conditions used. The HONO uptake on mineral aerosol (calculated with uptake data for HONO on Al2O3 surface) appears to be of minor importance compared with other HONO loss processes in the boundary layer of the earth atmosphere. (C) 2012 Elsevier B.V. All rights reserved.

Abstract  Nitrous oxide is a potent greenhouse gas, and it destroys stratospheric ozone(1). Seventeen per cent of agricultural nitrous oxide emissions come from the production of nitrous oxide in streams, rivers and estuaries(2), in turn a result of inorganic nitrogen input through leaching, runoff and sewage. The Intergovernmental Panel on Climate Change and global nitrous oxide budgets assume that riverine nitrous oxide emissions increase linearly with dissolved inorganic nitrogen loads, but data are sparse and conflicting(2,3). Here we report measurements over two years of nitrous oxide emissions in the Grand River, Canada, a seventh-order temperate river that is affected by agricultural runoff and outflow from a waste-water treatment plant. Emissions were disproportionately high in urban areas and during nocturnal summer periods. Moreover, annual emission estimates that are based on dissolved inorganic nitrogen loads overestimated the measured emissions in a wet year and underestimated them in a dry year. We found no correlations of nitrous oxide emissions with nitrate or dissolved inorganic nitrogen, but detected negative correlations with dissolved oxygen, suggesting that nitrate concentrations did not limit emissions. We conclude that future increases in nitrate export to rivers will not necessarily lead to higher nitrous oxide emissions, but more widespread hypoxia most likely will.

Abstract  New insight in the mechanism of the so-called "Fast SCR" reaction over a commercial Fe zeolite catalyst was gained by an in situ FTIR investigation of the evolution of the surface intermediates during step response runs addressing the adsorption of NO2, as well as the reactivity of surface NOx with NH3 and with NO. The collected data, combined with the analysis of companion transient flow reactor experiments demonstrating the corresponding dynamics of gaseous reactants and products, confirm the key role of ferric nitrites/nitrates in the reaction pathway, and emphasize the cooperative interaction between the zeolite acidic sites, where ammonia is stored, and the Fe red-ox sites of the catalyst, which are involved in the critical reduction of surface nitrates by NO. (C) 2011 Elsevier B.V. All rights reserved.

Abstract  The MS5002E is a 32 MW-class, two-shaft gas turbine suitable for both mechanical and generator drive applications. Its design, based on the latest heavy-duty gas turbine technology, delivers 36% of thermal efficiency and maintains NOx emissions below 25 ppm.

After an extensive validation program performed on the First Engine to Test (FETT), the first production unit was shipped to the Yara fertilizer company for its ammonia and nitrate fertilizer plant at Sluiskil in the Netherlands. Yara is the world's largest supplier of crop nutrients, with sales to more than 120 countries.

The unit entered into commercial operation on November 2007, supporting Yara in meeting its environmental plan by replacing an existing, less efficient gas turbine. The engine is operated in generator drive mode, producing 30+ MW of electric power and 50 tons per hour of steam, which is used in the plant process. As of this writing, the unit has exceeded 18,000 hours of continuous service. The performance results and reliability are unusually high for a new machine.

This article reports the experience accumulated on the gas turbine during field operations, based both on the day-by-day activity (condition monitoring) and on the special introductory inspection program carried on to date. The improvements already introduced and being introduced on subsequent fleet units are discussed as well.

The day-by-day monitoring is supported by an extensive quantity of data collected from the machine and sent via Internet connection to the GE Oil&Gas Remote Monitoring & Diagnostic Center in Florence.

Abstract  The various methods for improving chloride penetration resistance in the reinforced concrete have been developed. Among the related general ways, using of corrosion inhibitor became very common. Therefore, in this study, in order to comprehend performance of corrosion inhibitor, the experiment study was conducted about corrosion characteristic of 3 steps(0.0, norm 1/2, norm) compared to organic corrosion inhibitor standard use of liquid and molar 3 steps(0.0, 0.3, 0.6%) of Chloride by added amount of inorganic corrosion inhibitor by the corrosion inhibitor types about 2.4kg/m(3), 4.8k/m(3) based on Chloride ion content 1.2kg/m(3) for service life prediction of concrete structure by using Poteniostat. As results, in the case of inorganic nitrous acid corrosion inhibitor, it was confirmed that anti-corrosive performance of Chloride ion content 1.2kg/m(3) by corrosion Ecorr -0.30V in more than molar ratio 0.3%, and it also was confirmed that anti-corrosive performance of 2.4kg/m(3), 4.8kg/m(3) in more than molar ratio 0.6%. In addition, the excellent anti- corrosive performance of organic corrosion inhibitor was shown in 1/2(0.42kg/m(3)) of norm regardless of Chloride ion content, and it can be seen that absorption types organic corrosion inhibitor has excellent anti-corrosive performance compared to the inorganic nitrous acid corrosion inhibitor by the added amount of corrosion inhibitor.

Abstract  One novel means of biofuel production requires the reduction of nitrite ions to produce ammonia (which serves as an electron source for genetically-modified, carbon dioxide-fixing bacteria). The feasibility of this process depends on the performance of both the electrochemical reactor and a coupled bioreactor. We report on characterization of the electrochemical process involving nitrite reduction to ammonia in buffered electrolytes in the pH range between 6.0 and 8.0. A limiting current plateau was observed and determined to be due to flux of phosphate buffer (the primary source of protons) to the electrode surface. Importantly to the development of a sustainable process, current efficiencies of nitrite reduction to ammonia of 100% on both nickel and glassy carbon electrodes are possible. A divided flow-by porous electrode cell was designed as a proof of principle by coupling it to the bioreactor. It was observed that the overpotential of glassy carbon cathode decreased by similar to 500 mV over 10 days which would correspond to 24% decrease in power requirements for the electrochemical reactor. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.042301jes] All rights reserved.

Abstract  Nephrotoxicity is one of the serious dose limiting side effects of cisplatin when used in the treatment of various malignant conditions. Accumulating evidence suggests that oxidative stress caused by free radicals and apoptosis of renal cells contributes to the pathogenesis of cisplatin-induced nephrotoxicity. Present study was aimed to explore the effect of carnosic acid, a potent antioxidant, against cisplatin induced oxidative stress and nephrotoxicity in rats. A single dose of cisplatin (7.5 mg/kg) caused marked renal damage, characterized by a significant (P < 0.05) increase in serum creatinine, blood urea nitrogen (BUN) and relative weight of kidney with higher kidney MDA (malondialdehyde), tROS (total reactive oxygen species), caspase 3, GSH (reduced glutathione) levels and lowered tissue nitrite, SOD (superoxide dismutase), CAT (catalase), GSH-Px (glutathione peroxidase), GR (glutathione reductase) and GST (glutathione S-transferase) levels compared to normal control. Carnosic acid treatment significantly (P < 0.05) attenuated the increase in lipid peroxidation, caspase-3 and ROS generation and enhanced the levels of reduced glutathione, tissue nitrite level and activities of SOD, CAT, GSH-Px, GR and GST compared to cisplatin control. The present study demonstrates that carnosic acid has a protective effect on cisplatin induced experimental nephrotoxicity and is attributed to its potent antioxidant and antiapoptotic properties. (C) 2011 Elsevier Ltd. All rights reserved.

Abstract  The objective of this study was to examine the role of nitrate reductase, nitric oxide and non-symbiotic hemoglobin in imparting waterlogging tolerance in mung bean genotypes. Experiment was conducted with two cultivated mung bean [Vigna radiata (L.) Wilczek] genotypes T 44 (tolerant) and Pusa Baisakhi (susceptible) and a highly tolerant wild species Vigna luteola (Jacq.) Benth. The content of nitric oxide increased up to 6 d of waterlogging in Vigna luteola and T 44, and up to 4 d of treatment in Pusa Baisakhi. Increase in nitrate reductase (NR) activity was observed only up to 4 d of waterlogging in Vigna luteola and T 44, and up to 2 d of treatment in Pusa Baisakhi, and thereafter the activity decreased in all the genotypes. The increase in NO content and NR activity was greater in Vigna luteola and T 44 than in Pusa Baisakhi. Non-symbiotic hemoglobin (NSHb) and cNR mRNA expressions were observed only in waterlogging treated roots of Vigna luteola and T 44, while very little expression was observed in control plants of Vigna luteola and T 44, and in control and waterlogged plants of Pusa Baisakhi. PCR bands of Hb and cNR were cloned, and nucleotide and deduced amino acid sequences were obtained and conserved regions and domains were identified using database.

Abstract  Zn-Al layered double hydroxides (LDH) are promising as nanocontainers of corrosion inhibitors in self-healing corrosion protection coatings. Zn(2)Al- vanadate (Zn/Al = 2:1) is prepared by anion exchange from the parent composition Zn(2)Al-nitrate at pH similar to 8. Crystal structure and vibrational spectra of both LDHs have been studied in comparison. Their interlayer distances are rather larger than those corresponding to the most compact arrangement of the intercalated anions. Nevertheless, no sign of a turbostratic disorder has been detected in these LDH. Based on the analysis of the spectroscopic data in combination with the XRD results, it has been shown that vanadate anion, which substitutes nitrate at the anion exchange, is pyrovanadate, V2O74-. The observed disorder in the hydroxide layers in Zn(2) Al-V2O7 is likely to result from strong interactions between V5+ and Zn2+/Al-3. Although Zn(2) Al-NO3 is less disordered than Zn(2) Al-V2O7, it exhibits no long-range order in arrangement of cations in the hydroxide layers. (C) 2012 Elsevier B. V. All rights reserved.

Abstract  A simple thermal decomposition route has been developed to prepare single-phase cubic ZrO2 nanospheres by [Zr(sal)(3)(H2O)(2)](NO3) as the new precursor. The ZrO2 nanocrystals have been prepared by bis-aqua, tris-salicylaldehydato zirconium(IV) nitrate; [Zr(sal)(3)(H2O)(2)](NO3), as precursor in oleylamine (C18H37N) and triphenylphosphine (C18H15P). To control the particle size, combination of C18H37N and C18H15P were applied as surfactants. The C18H37N and C18H15P play an important role in preventing aggregation of ZrO2 nanocrystals. The products were characterized by X-ray diffraction, transmission electron microscopy, photoluminescence spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy to depict the phase and morphology. The FT-IR spectrum showed the purity of obtained ZrO2 nanocrystals with cubic phase.

Abstract  Nitrous oxide is a potent atmospheric greenhouse gas(1) that contributes to ozone destruction(2). Biological processes such as nitrification and denitrification are thought to drive nitrous oxide production in soils, which comprise the largest source of nitrous oxide to the atmosphere(1). Here we present measurements of the concentration and isotopic composition of nitrous oxide in soil pore spaces in samples taken near Don Juan Pond, a metabolically dormant hypersaline pond in Southern Victoria Land, Antarctica in 2006, 2007 and 2008, together with in situ fluxes of nitrous oxide from the soil to the atmosphere. We find fluxes of nitrous oxide that rival those measured in fertilized tropical soils(3). Laboratory experiments -in which nitrite-rich brine was reacted with a variety of minerals containing Fe(II)-reveal a new mechanism of abiotic water-rock reaction that could support nitrous oxide fluxes at Don Juan Pond. Our findings illustrate a dynamic and unexpected link between the geosphere and atmosphere.

Abstract  We studied the effect of locomotor activity on the ultrastructure of cerebellar neurons, neurological disturbances, and survival rate in Krushinsky-Molodkina rats during the development of hemorrhagic induced by acoustic stress. In animals with high spontaneous locomotor activity, severe edema of cerebellar neurons (resulting in the destruction of surrounding structures) and swelling of the synapses (terminals of mossy fi bers on granule cell dendrites) were observed. By contrast, the areas of intracerebral, subdural, and subarachnoid hemorrhages were lower in rats under conditions of forced rest.

Abstract  Sulfate and nitrate records from 5 ice cores spread across Svalbard were compared and revealed strong temporal similarities with previously published global estimates of SO2 and NOx anthropogenic emissions during the 20th century. A significant departure from the early century sulfate and nitrate levels was evident at all drilling sites starting from the mid-1940s. A steady increase was observed in both sulfate and nitrate profiles at most sites until the late 1960s, when the annual concentrations started to increase at a higher rate. This peak activity lasted for about a decade, and was observed to decrease steadily from the early 1980s on, when sulfate levels declined significantly and when nitrate levels finally reached sulfate levels for the first time in 20th century. The timing of these trends in Svalbard with global SO2 and NOx concentration profiles was best appraised when considering composite concentration profiles of all Svalbard ice cores for sulfate and nitrate, respectively. Composite profiles were also found to provide a convenient mean for distinguishing between the most important world source regions. Based on correlation analysis, the major pollutant sources appeared to be Western Europe and North America for both sulfate and nitrate, followed by Central Europe and former U.S.S.R. in generally similar proportions.

Abstract  An electronically polarizable model has been developed for the ionic liquid (IL) 1-ethyl-3-methyl-imidazolium nitrate (EMIM(+)/NO(3)(-)) (Yan et al. J. Phys. Chem. B DOI:10.1021/jp9089112). Molecular dynamics simulations were then performed with both the polarizable and nonpolarizable models. Both models exhibited certain properties that are similar to a supercooled liquid behavior even though the simulations were run at 400 K (89 K above the melting point of EMIM(+)/NO(3)(-)). The ionic mean-squared displacement and transverse current correlation function of both models were well represented by a memory function with a fast Gaussian initial relaxation followed by the two-step exponential functions for beta- and alpha- structural relaxations. Another feature shared by both models is the dynamic heterogeneity, which highlights the complex dynamic behavior of ILs. Apart from the overall slow dynamics, the relaxation of the H-atoms attached to the methyl group demonstrates a "free rotor" type of motion. Also, the ethyl group shows the fastest overall relaxation, due to the weak electrostatic interactions on it. Such flexibility enhances the entropic effect and thus favors the liquid state at room temperature. For the dynamical properties reported in this paper, the polarizable model consistently exhibited faster relaxations (including translational and reorientational motions), higher self-diffusion and ionic conductivity, and lower shear viscosity than the nonpolarizable model. The faster relaxations of the polarizable model result from attenuated long-range electrostatic interactions caused by enhanced screening from the polarization effect. Therefore, simulations based on the polarizable model may be analogous to simulations with the nonpolarizable model at higher temperatures. On the other hand, the enhanced intermolecular interactions for the polarizable model at short-range due to the additional charge-dipole and dipole-dipole interactions result in a red shift of the intramolecular C-H stretch spectrum and a higher degree of ion association, leading to a spectrum with enhanced conductivity across the whole frequency range. The vibrational motion associated with the intermolecular hydrogen bonding is highly IR active, highlighting the importance of hydrogen bond dynamics in ILs.

Abstract  In this study, we reported that a bioluminescent assay for nitric oxide (NO) was developed utilizing the biological enzyme activity of soluble guanylate cyclase (sGC) and a bioluminescent assay for pyrophosphate involving the pyruvate phosphate dikinase (PPDK)-luciferin/Luciferase reaction. Pyrophosphate (PPi), which is released concomitantly when NO binds to soluble guanylate cyclase, was measured employing the PPDK/Luciferase reaction. NO binds to soluble guanylate cyclase specifically; thus, this assay is undisturbed by nitrate anhydride, NO(2)(-) or NO(3)(-). Consequently, the measurable range of NO obtained in the proposed method is 200-20,000 nM; the detection limit was 200 fmol/assay. NO released from nitrate medicine was measured utilizing this assay. As a result, NO released from isosorbide nitrate was detected. In conclusion, we suggest in this report that the technique for NO might be suitable as a quality check method for the pharmacodynamic action of nitrate medicines and in development of new medicines.

Abstract  To verify the effect of the transcription factor OsDof25 on the nitrogen metabolism in plants, it was cloned for expression in Arabidopsis thaliana under the control of the 35S promoter. Lineages with different expression levels of this gene were obtained, and when grown in a half-strength MS medium (10 mM of NH4 (+) and 20 mM of NO3 (-)) showed phenotypes with visible chloroses and growth disorders. It was observed that OsDof25 increased the levels of expression of high and low affinity ammonium transporters (AtAMT1.1 and AtAMT2.1, respectively) and repressed the high affinity nitrate transporter (AtNRT2.1). We also verified an increase in total amino-N content and expressions of the pyruvate kinase (PK1 and PK2), phosphoenolpyruvate carboxylase (PEPC1 and PEPC2) and NADP-dependent and NAD-dependent isocitrate dehydrogenase. In addition, an increase in expression levels and activity of glutamate dehydrogenase was also observed. The simultaneous increase in the expression of AMTs and enzymes of carbon metabolism may explain the high levels of amino-N found in the transgenic plants. The data found in this work suggest that OsDof25 expression simultaneously affects NH4 (+) uptake and organic acid metabolism in plants.

Abstract  The spatial distribution of interstitial NO2(-) concentrations was studied in NO3(-)-exposed freshwater sediment microcosms, using pore water extractions as well as ion-selective microsensors. Porewater extractions revealed ecotoxicologically critical NO2(-) concentrations in hypoxic and anoxic sediment layers in which significant NO3(-) consumption took place. In contrast, the use of ion-selective microsensors demonstrated the high capacity of the thin oxic surface layer of the sediments to consume NO2(-) and to produce NO3(-). Two modes of NO3(-) supply to the sediments were compared: In treatments with NO3(-) supply to the overlying water, a subsurface maximum of NO2(-) concentration was observed, coinciding with the site of maximum NO3(-) consumption. When NO3(-) was perfused up through the sediment cores, however, NO2(-) accumulated throughout the entire sediment column. Such spatially extensive NO2(-) accumulations were only observed in sediments poor in organic matter with a relatively high permeability. By manipulating the O2 content of the overlying water, the release of NO2(-) from the sediments could be influenced: In treatments with air-saturated overlying water, the sediments did not release detectable amounts of NO2(-) into the water phase. When kept hypoxic (25% air saturation) instead, significant NO2(-) accumulations were recorded in the overlying water. These findings suggest that in treatments with air-saturated overlying water, NO2(-) that was produced in deeper sediment layers (denitrifying conditions) was completely consumed at the oxic sediment surface (nitrifying conditions) before it could reach the overlying water.

Abstract  Aspects of denitrification and benzoate degradation were studied in two estuarine microbial mat communities on the California coast by measuring the depth distributions of potential denitrification rates, genetic potential for denitrification, nitrate concentration, benzoate mineralization rates, total bacterial abundance, and abundance of a denitrifying strain (TBD-8b) isolated from one of the sites. Potential denitrification was detected in microbial mat cores from both Elkhorn Slough and Tomales Bay. Maximum denitrification rates were more than two orders of magnitude higher at Elkhorn Slough (3.14 mmol N m -2 d -1) than at Tomales Bay (0.02 mmol N m -2 d -1), and at both sites, the maximum rates occurred in the 0-2 mm depth interval. Ambient pore [NO 3 + NO 2] was substantially higher at Elkhorn Slough than at Tomales Bay. Incorporation and mineralization of benzoate was maximal near the mat surface at Elkhorn Slough. The areal rate of benzoate utilization was 1045 nmol C m -2 d -1, which represented utilization of 70% of the added substrate in 24 h. Total bacterial and TBD-8b abundances were greatest near the surface at both Tomales Bay and Elkhorn Slough, and TBD-8b represented less than 0.2% of the total. Genetic potential for denitrification, quantified by hybridization with a nitrite reductase gene fragment, was present below the mat surface at average levels representing presence of the gene in approximately 10% of the total cells.