Search results for "nitrate"
showing 10 items of 580 documents
Use of functional genes to quantify denitrifiers in the environment.
2006
During the last decade, application of molecular methods using cultivation-independent approaches has provided new insights into the composition and structure of denitrifying communities in various environments. However, little is known about their abundance, and quantification is still performed using cultivation-based approaches, which are not only biased by the inability to cultivate of many micro-organisms but also fastidious and time-consuming. Two types of cultivation-independent approaches have recently been developed to quantify denitrifiers. The first type, which is based on the hybridization technique, comprises the use of Southern hybridization and DNA arrays. The second type, ba…
Aircraft-based operation of an aerosol mass spectrometer: Measurements of tropospheric aerosol composition
2006
The Aerodyne quadrupole aerosol mass spectrometer was deployed on the Falcon twin jet research aircraft operated by Deutsches Zentrum für Luft- und Raumfahrt (DLR). This was the first deployment of an AMS in a jet aircraft. Aerosol mass concentration measurements in the troposphere up to altitudes of about 11 km were performed within two measurement flights on 12 and 14 May 2003 over southern Germany. Background aerosol data were gained up to 6 km, while aircraft exhaust aerosol was be sampled at higher altitudes on 14 May, indicating the presence of sulfuric acid and unburned hydrocarbons in the exhaust particles. The boundary layer aerosol on 12 May was found to be composed of 49% organic…
Effetti delle epoche e modalità di concimazione su produzione e qualità del finocchio. Effects of time and method of fertilizer application on yield …
2010
Two field trials were carried out in Sicily during fall-winter and spring season to determine the influence of 9 fertilization treatments, obtained by changing the time (pre-plant and/or post-plant fertilization), and method (broadcast fertilization and/or fertigation) of fertilizer application and the type of fertilizer (mineral, organic, slow release fertilizers) on yield and quality of fennel. An unfertilized treatment (control) was also included. In all fertilized treatments, macronutrients were applied at the following total rates (kg ha-1): N (350), P2O5 (100), K2O (208). In both trials the highest yield and mean bulb weight was obtained by pre-planting application of all mineral fert…
Effect of commercial mineral-based additives on composting and compost quality.
2009
Abstract The effectiveness of two commercial additives meant to improve the composting process was studied in a laboratory-scale experiment. Improver A (sulphates and oxides of iron, magnesium, manganese, and zinc mixed with clay) and B (mixture of calcium hydroxide, peroxide, and oxide) were added to source-separated biowaste:peat mixture (1:1, v/v) in proportions recommended by the producers. The composting process ( T , emissions of CO 2 , NH 3 , and CH 4 ) and the quality of the compost (pH, conductivity, C/N ratio, water-soluble NH 4 –N and NO 3 –N, water- and NaOH-soluble low-weight carboxylic acids, nutrients, heavy metals and phytotoxicity to Lepidium sarivum ) were monitored during…
Use of Calcined Dolomite as Chemical Precipitant in the Simultaneous Removal of Ammonium and Phosphate from Synthetic Wastewater and from Agricultura…
2019
Phosphorus as phosphate and nitrogen as ammonium or nitrate are the main nutrients in wastewaters and agricultural sludges. They runoff easily to waterways and cause eutrophication in water bodies. However, ammonium and phosphate could be precipitated simultaneously and used as recycled nutrients. In this research, dolomite calcined at 650 °
An operon for histidine biosynthesis in Streptomyces coelicolor
1973
On the assumption that a cluster of five his genes (eight cistrons) in S. coelicolor corresponds to an operon, a genetic analysis of a constitutive mutant was carried out. This strain has a multi-site mutation localized at the (conventional) right end of the his cluster and is derepressed for at least two enzymes coded by genes of the cluster. The study of suitable heterozygous clones (heteroclones), showed the mutation to be cis-dominant, suggesting that the operator region is affected. Most likely the strain has a deletion connecting the his operon to an adjacent amm (ammonium requirement) operon as demonstrated by its inability to utilize nitrate as nitrogen source and to complement or r…
Recovery of mutants impaired in pathogenicity after transposition of Impala in Fusarium oxysporum f.sp. melonis
2000
The ability of transposon impala to inactivate genes involved in pathogenicity was tested in Fusarium oxysporum f. sp. melonis. Somatic excision of an impala copy inserted in the nitrate reductase-encoding niaD gene was positively selected through a phenotypic assay based on the restoration of nitrate reductase activity. Independent excision events were analyzed molecularly and shown to carry reinsertedimpala in more than 70% of the cases. Mapping of reinserted impala elements on large NotI-restriction fragments showed that impala transposes randomly. By screening 746 revertants on plants, a high proportion (3.5%) of mutants impaired in their pathogenic potential was recovered. According t…
Redox regulation of genome stability by effects on gene expression, epigenetic pathways and DNA damage/repair
2015
Reactive oxygen and nitrogen species (e.g. H2O2, nitric oxide) confer redox regulation of essential cellular signaling pathways such as cell differentiation, proliferation, migration and apoptosis. In addition, classical regulation of gene expression or activity, including gene transcription to RNA followed by translation to the protein level, by transcription factors (e.g. NF-κB, HIF-1α) and mRNA binding proteins (e.g. GAPDH, HuR) is subject to redox regulation. This review will give an update of recent discoveries in this field, and specifically highlight the impact of reactive oxygen and nitrogen species on DNA repair systems that contribute to genomic stability. Emphasis will be placed …
Toxicity of silver nanoparticles to Lumbriculus variegatus is a function of dissolved silver and promoted by low sediment pH
2017
Toxicity of silver nanoparticles (AgNPs) to benthic organisms is a major concern. The use of AgNPs in industry and consumer products leads to increasing release of AgNPs into the aquatic environment-sediments being the major sink. Effects of sediment pH on the toxicity of AgNPs to benthic oligochaeta Lumbriculus variegatus were studied in a 23-d toxicity test. Artificially prepared sediments (pH 5 and 7) were spiked with varying concentrations of uncoated AgNP, polyvinylpyrrolidone (PVP)-coated AgNP, and silver nitrate (AgNO3 ) as dissolved Ag reference. Number of individuals and biomass change were used as endpoints for the toxicity. The toxic effects were related to the bioaccessible conc…
Spatiotemporal Variations in the Abundance and Structure of Denitrifier Communities in Sediments Differing in Nitrate Content
2017
Spatial and temporal variations related to hydric seasonality in abundance and diversity of denitrifier communities were examined in sediments taken from two sites differing in nitrate concentration along a stream Doñ