Use Of Nitrogen Compounds Research Articles

The function of high-affinity urea transporters in nitrogen-deficient conditions.

Urea is the most used nitrogenous fertilizer worldwide and an important nitrogen-containing plant metabolite. Despite its major use as fertilizer, its direct uptake is limited due to the ubiquitous presence of bacterial urease, which leads to the formation of ammonium. In this review, we will focus mainly on the more recent research about the high-affinity urea transporter function in nitrogen-deficient conditions. The effective use of nitrogenous compounds is essential for plants to be able to deal with nitrogen-deficient conditions. Leaf senescence, either induced by development and/or by nitrogen deficiency, plays an important role in the efficient use of already assimilated nitrogen. Proteinaceous nitrogen is set free through catabolic reactions: the released amino acids from protein catabilization are in turn catabolized leading to an accumulation of ammonium and urea. The concentration and conversion to transportable forms of nitrogen, e.g. amino acids like glutamine and asparagine, are coordinated around the vascular tissue. Urea itself can be translocated directly over the phloem by a mechanism that involves DUR3, or it is converted by urease to ammonium and assimilated again into amino acids. The details of the high-affinity transporter function in this physiological context and the implications for crop yield are explained.

Performance and metabolite profile of dairy cows fed tropical grasses and concentrates containing crude protein with low or high degradability

Ten Holstein-Zebu crossbred cows distributed into two simultaneous Latin squares (5 × 5) as a 2 × 2 factorial arrangement formed by chopped sugarcane or elephant grass silage, both with high or low protein degradability supplements and a corn silage as a control treatment, were compared using orthogonal contrasts. The studied variables were the performance, plasma concentrations of urea-N, glucose, and creatinine, urine-N and milk urea-N, and the nychthemeral variation in NH3-N in the rumen fluid of dairy cows. Nutrient intake, milk production, and milk composition were affected by the treatments. The total mixed ration containing elephant grass silage combined with rumen undegradable protein (RUP) provided balanced amounts of carbon and nitrogen in the rumen. This effect may explain the 18% increase in milk yield compared with the other treatments. The diurnal pattern of ruminal NH3-N was interpreted with a sinusoid model. In general, cows fed elephant grass silage exhibited higher concentrations of blood plasma and milk urea-N than animals fed sugarcane. The cows that consumed elephant grass silage with rumen degradable protein concentrate showed a higher milk urea-N compared with animals that consumed elephant grass silage with the RUP concentrate. The use of diets based on corn silage leads to a better use of nitrogen compounds because these diets resulted in lower levels of urea-N in the plasma, urine, and milk at the same level of milk production compared with diets containing elephant grass silage or chopped sugarcane as roughages. In sugarcane-based diets, even greater nitrogen losses in the urine are observed, despite the presence of readily fermentable carbohydrates in the diet.

Floating bioplateau for treatment of waste quarry waters from mineral nitrogen compounds at the arctic conditions

Bioplateau creation researches at Kirovogorsky sediment pond of AO "OLKON" (Olenegorsk, Murmansk Region) have been carried out for the purpose of decrease in water of mineral nitrogen compounds ingressive into the pond with waste quarry waters as a result of explosive works with the use of nitrogen compounds. The assortment of indigenous plants has been selected; the method of their fixing and cultivation on the water surface is developed; and observation of their vegetation is carried out. In the conditions of laboratory and full-scale experiments, the dynamics of decreasing the mineral forms of nitrogen compounds is found. The necessary area of the pond bioplateau coating for decrease of the mineral nitrogen compounds is calculated. Application of the floating bioplateaus promoted decrease in water of the sediment pond of the contents of ammonium and nitrite nitrogen to values of maximum concentration limit and lower. The trend of nitric nitrogen concentration decrease is marked as well. The developed process can be applied in any climatic zone with characteristic to the locality assortment of plant-improvers.

Sequential Use of Nitrogen Compounds by Saccharomyces cerevisiae during Wine Fermentation: a Model Based on Kinetic and Regulation Characteristics of Nitrogen Permeases

The efficiency of nitrogen use is a key determinant of the completion of alcoholic fermentation. We analyzed the kinetics of consumption of 18 nitrogen compounds by 14 Saccharomyces cerevisiae strains of various origins in a synthetic medium that mimicked a grape must. The kinetic profiles of total nitrogen consumption were diverse, but the order of nitrogen source consumption was similar for all strains. The nitrogen compounds could be classified into three groups, according to their order of use: prematurely consumed (Lys), early consumed (Asp, Thr, Glu, Leu, His, Met, Ile, Ser, Gln, and Phe), and late consumed (ammonium, Val, Arg, Ala, Trp, and Tyr). The initial concentrations of these compounds did not alter the order in which they were consumed, except for arginine and ammonium. Early consumed amino acids are transported by specific permeases under Ssy1p-Ptr3p-Ssy5 (SPS)-mediated control that are expressed at the beginning of consumption. Most nitrogen compounds consumed late are transported by permeases under nitrogen catabolite repression (NCR), and others (Val, Trp, and Tyr) are transported by SPS-regulated low-affinity permeases. Therefore, the kinetic characteristics of transporters, as well as SPS and NCR, are likely key factors controlling the temporal sequence of consumption of nitrogen compounds and constitute a system highly conserved in S. cerevisiae species. This work sheds new light on the mechanistic basis of the sequential use of different nitrogen compounds in complex environments.

Influence of SO 2 on the consumption of nitrogen compounds through alcoholic fermentation of must sterilized by pulsed electric fields

The aim of this work was to study the influence of SO 2 on the use of nitrogenous compounds by yeast during wine alcoholic fermentation. Thus Parellada must was sterilized by a pulsed electric field treatment and inoculated with Saccharomyces cerevisiae Na33 strain. The fermentations were carried out with SO 2 (20 mg/l) and without SO 2. Results showed that yeast better consumed the amino acids in the first half of fermentation in the presence of SO 2. The final concentration of amino acids in the obtained wine was greater when the must was fermented without SO 2 than when the latter compound was present. Therefore, the presence of SO 2 facilitated the consumption of amino acids and, hence, such wine should have more complex flavour and better microbiological stability than that obtained from fermentation without SO 2.

Research on the direction of secondary migration of oil by making use of nitrogen compounds as tracers in the No. 6 area of the Melut Basin

This paper discussed the direction of secondary migration of oil in the No. 6 area of the Melut Basin by making use of nitrogen compounds as secondary oil migration tracers. From the results, we have found that the occurrence and compositional characteristics of isomeric-nitrogen compounds in crude oil precisely manifest the fractionation effect of oil migration: with increasing secondary migration distance, the absolute concentrations tend to decrease, and the ratio of nitrogen-shielded isomers to nitrogenexposed isomers tends to increase. It is considered that the main direction of oil migration in the No. 6 area of the Melut Basin is from north to south.

Gestion de l'azote en syst�me d'�levage d�velopp�. Enjeux scientifiques et environnementauxNitrogen management from intensive livestock production : scientific and environmental issues

Growing environmental concern led to increased public and scientific attention to nitrogen transfers from animal manure and slurry. Major environmental problems arise from the excessive use of nitrogen compounds. Amongst these are (i) acidification of forests and natural ecosystems through atmospheric deposition of ammonia (NH3), (ii) eutrophication of inland waters and coastal seas mainly by organic N and nitrates, (iii) contamination of groundwater by nitrates and (iv) a contribution to the global warming problem by nitrous oxide, N2O. Tracer methods using 15N stable isotope provide and excellent tool for studying such complex transfers during the different stages of animal slurry management including storage, treatment and land spreading. In this article, we present a brief review of isotopic tracer principles and history through a general description of terms, definitions and assumptions follow by the methodologies developed in our laboratory to label the ammoniacal nitrogen fraction of pig slurry using artificial 15N enrichment. The aim of our studies is to gather information concerning nitrogen pig slurry turnover and to focus on those processes, where major progress is made using the stable isotope 15N. Recent research findings are Presented. La connaissance du cycle de l'azote des déjections animales (lisiers) est un enjeu primordial au regard de préoccupations environnementales : accroissement de l'efficacité agronomique et/ou réduction des pollutions atmosphériques. Dans ce contexte, l'utilisation du traceur isotopique 15N permet de quantifier les différents mécanismes (assimilation et réorganisation, minéralisation, volatilisation, nitrification—dénitrification) et d'étudier les voies de transferts possibles. La technique développée consiste notamment à marquer la fraction azote ammoniacal du lisier par ajout direct de sulfate d'ammonium ou d'urée enrichis en 15N. Des essais en laboratoire illustrent les processus de nitrification - dénitrification ainsi que les transferts d'azote sous forme de protoxyde d'azote (N2O). Par ailleurs le suivi du devenir de l'azote après épandage de lisier au champ, permet d'établir un bilan sol—plante—air. Au travers de ces expériences, l'utilisation du marquage isotopique 15N de l'azote des déjections animales apparaît comme un outil de première importance.

Use of nitrogen compounds in spontaneous and inoculated wine fermentations.

In this paper the use of nitrogen compounds in garnacha must inoculated with active dry wine yeast Saccharomyces cerevisiae subsp. cerevisiae strain Na33 has been studied. The results are compared to garnacha must fermented with indigenous yeasts (control must). In the samples where the inoculated yeast predominated, no qualitative differences were appreciated in the use of amino acids with respect to the control samples, although there were quantitative differences. In the musts where the Na33 strain dominated, a lesser quantity of amino acids were consumed at the beginning of fermentation than in the control samples. For that reason, probably, this yeast showed problems in competing for the nitrogen nutrients of the must; this could have made its implantation in one of the inoculated samples more difficult. At the end of fermentation the Na33 strain continued to consume amino acids at high concentrations of ethanol. Its high tolerance to this toxic could be favored by the production and rehydration of dry wine yeast in the presence of air.