Dissertations / Theses: 'Nitrite metabolism'

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Pinder, Andrew George. "Nitrite uptake and metabolism in human erythrocytes : a source of vascular nitric oxide?" Thesis, Cardiff University, 2009. http://orca.cf.ac.uk/55834/.

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The primary function of the cardiovascular and pulmonary systems is to produce a flow of oxygenated blood in sufficient supply to maintain aerobic metabolism in all organs and tissues. The system is required to be energy efficient but also receptive to changes in cellular metabolic demand. In order to function both at rest and during demand the system must also match oxygen allocation to metabolic requirements at a localised level. Once blood enters an area that requires substrates, oxygen should have the capacity to efficiently move from the blood, across the vessel wall and into the tissue. Global oxygen delivery (DO2, product of cardiac output and arterial oxygen content) under normal, resting conditions is more than adequate to meet metabolic demands/oxygen consumption (VO2) (Figure 1.1). At a tissue level, oxygen delivery is governed by two processes, convective and diffusive oxygen transport. Convective transport can be described as the bulk movement of oxygen in the blood, encompassing changes in cardiac output and the mechanisms that regulate flow in the microcirculation. Diffusive oxygen transport simply refers to the movement of oxygen from the blood into tissue, down the capillary-intracellular oxygen tension (PO 2) gradient and is governed by arterial oxygen tension (PaO2).

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Mackerness, Craig William. "The products of bacterial metabolism of nitrate and nitride and human cancer." Thesis, Open University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.334761.

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Kotwica, Aleksandra Olga. "Dietary nitrate and the modulation of energy metabolism in metabolic syndrome." Thesis, University of Cambridge, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708924.

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Camargos, Liliane Santos de. "Análise das alterações no metabolismo de nitrogênio em Canavalia ensiformes (L.) em resposta a variações na concentração de nitrato fornecida." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/11/11144/tde-25022003-141208/.

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O nitrogênio é o nutriente mineral essencial mais limitante ao crescimento das plantas. Apenas alguns microorganismos procariotos desenvolveram um mecanismo bioquímico que permite reduzir N2, abundante na atmosfera, a amônia, que pode ser assimilada pelas plantas. Muitos destes microorganismos conseguem associar-se simbioticamente com outros organismos, sendo a associação de bactérias do grupo Rhizobium com plantas do grupo das leguminosas a mais importante a nível econômico. Por outro lado, quando existe disponibilidade de nitrato no meio ambiente, a leguminosa abandona a fixação biológica absorvendo nitrato, que é reduzido a amônia pelas enzimas nitrato redutase (NR) e nitrito redutase (NiR) e, ao final, assimilada pelo sistema GS/GOGAT. Apesar de as duas vias terem amônia como produto final, em leguminosas tropicais, principalmente as pertencentes à tribo Phaseolae, quando a amônia provém de associação simbiótica a planta exporta, via xilema, preferencialmente ureídeos, enquanto quando a amônia provém da redução de nitrato, a planta exporta amidas, principalmente asparagina e glutamina. O objetivo do presente trabalho foi identificar, em Canavalia ensiformes (L.), as alterações metabólicas que ocorriam em função da concentração de nitrato fornecida à planta, através da quantificação localizada dos principais compostos nitrogenados do metabolismo de nitrogênio e dos principais sítios de redução de nitrato; bem como estudar o metabolismo de asparagina na leguminosa em questão desde o estádio de germinação até a fase reprodutiva, identificando os sítios preferenciais de metabolismo desta amida. Observou-se que o metabolismo de aminoácidos foi profundamente alterado em função da concentração de nitrato fornecida. Os níveis de aminoácidos solúveis totais não se alteraram drasticamente, o mesmo ocorrendo com os níveis de proteína e ureídeos, considerando-se os diferentes tratamentos em um mesmo estádio de desenvolvimento. Com a alteração do estádio de desenvolvimento, especialmente com o início da fase reprodutiva, o metabolismo de nitrogênio foi profundamente alterado, observando-se inversão no sítio de redução de nitrato, alterações nas concentrações totais de ureídeos e aminoácidos e alterações profundas no metabolismo de aminoácidos, quando se relaciona com o estádio vegetativo. A atividade de nitrato redutase, em Canavalia ensiformes (L.) mostrou-se regulada pela concentração de glutamina presente nos tecidos, tendo se mostrado mais elevada nos tecidos onde os níveis de glutamina eram menores. A alteração no sítio de redução de nitrato em função da mudança no estádio de desenvolvimento foi acompanhada pelo aumento simultâneo na concentração de glutamina solúvel nos tecidos onde a atividade da enzima foi menor. Em função das mudanças no estádio de desenvolvimento, percebeu-se também uma redução no número de sítios de possível atividade da enzima asparaginase, o que foi inferido pela redução no número de tecidos onde a enzima esteve presente, sugerindo então um possível aumento no catabolismo desta amida por ação da enzima asparagina-aminotransferase. Para maior entendimento dos processos que levam às alterações no metabolismo de nitrato, asparagina e aminoácidos de uma forma geral, os mecanismos de síntese e utilização de aminoácidos devem ser analisados para melhor compreensão dos processos envolvidos, através da análise da atividade das principais enzimas envolvidas nestes processos, bem como de estudos da transcrição dos respectivos genes.
Nitrogen is the most limiting essential nutrient for plant growth. Some prokaryotic microorganisms have developed a biochemical mechanism, which allows the reduction of N2, which is abundantly present in the atmosphere, to ammonium that can be assimilated by the plants. Many of these microorganisms form symbiotic associations with other organisms. This is especially true for leguminous plants that form symbiotic associations with bacteria belonging to the Bradyrhizbium, Rhizobium, and Sinorhizobium groups. Bacterial nitrogen fixation from these interactions are extremely important for the global nitrogen balance and plays a major economically role in agriculture. On the other hand, when nitrate is available in the environment, leguminous plants interrupt the symbiotic fixation process to directly use of the nitrate, which is reduced to ammonium by the enzymes nitrate reductase (NR) and nitrite reductase (NiR), and is finally assimilated by the GS/GOGAST system. Although both will result in ammonium as the end-product, in tropical leguminous plants species, mainly those of the Phaseoleae tribe, when ammonium is produced by the symbiotic association the plant translocates mainly ureides via xylem, whereas the plant translocate mainly amides such as asparagine and glutamine, when the ammonium is produced by nitrate reduction. The objective of this study was to identify in Canavalia ensiformes (L.), metabolic alterations dependent upon the concentration of nitrate supplied to the plant. Specific attention was given to the quantity of nitrogen compounds from nitrogen metabolism and asparagine metabolism from the early stage of germination to the reproductive stage, with the identification of the main locations of metabolism for this amide. Amino acids metabolism was significantly altered when nitrate was supplied at different concentrations. Total soluble amino acids, total protein and ureide contents were not dramatically altered when considering the different treatments at the same developmental stage. However, nitrogen metabolism was shown to be drastically altered when different development stages were compared, particularly at the beginning of the reproductive stage, at which time a switch in the location of nitrate reduction, alterations in the total concentration of ureides and amino acids were observed, when compared to the vegetative stage. Nitrate reductase activity of Canavalia ensiformes was shown to be regulated by the concentration of glutamine present in the tissues, exhibiting higher activity in tissues containing lower concentrations of glutamine, which coincided with the shift of the site of nitrate reduction with the changing developmental stage. The understanding of the processes leading to the alterations in the metabolism of nitrate, asparagine, amino acids, and the mechanism related to the synthesis and utilization of amino acids requires further studies.

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Agell, Blenda. "Effect of Antibacterial Mouthwash on Basal Metabolic Rate in Humans : A Randomized, Double-blinded, Cross-over Study." Thesis, Linnéuniversitetet, Institutionen för kemi och biomedicin (KOB), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-30774.

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The use of mouthwash is a common complement to oral care. However, the physiological implication of this use, besides of effects on oral hygiene, is poorly known. The research of the gut micro flora and its implications on the host is a very active area of research today. Many important connections between the gut micro flora and obesity and diabetes have been found. These billions of bacteria are part of the immune system, they produce essential vitamins and they make inaccessible polysaccharides more digestible to the host, just to mention a few of their symbiotic roles for the host. A less explored area is the micro flora in the oral cavity. On the back of the tongue, anaerobic bacteria can reduce dietary nitrate to nitrite which then further can be reduced to nitric oxide, NO. NO is important in several important biological functions, e.g. as a signal substance, vasoregulation, mucus production and antibacterial effects. Vegetables as beetroot and spinach are dietary sources with a high nitrate content. Also drinking water and processed meats can be of relevance. Nitrite is added to processed meat for the prevention of botulism but also adds taste and color. Experiments on humans indicate that mitochondrial efficiency increases after nitrate load, manifested as a decreased oxygen demand during physical exercise. This can also be relevant under conditions where the mitochondrial function is impaired, such as in diabetes and cardiovascular diseases. First a pilot study was made to evaluate the nitrate reducing effect from the antibacterial mouthwash. The mouthwash proved very effective. The concentrations of nitrate and nitrite in saliva was analyzed by HPLC and saliva from the antibacterial treatment showed greatly reduced concentrations of nitrite and high concentrations of nitrate. Saliva from placebo mouthwash showed high concentrations of nitrite and low concentrations of nitrate as expected. To study the importance of oral bacteria on metabolism, we performed a randomized, cross-over double-blinded study with 19 healthy males between 22-43 years. During two separate three-day periods they used an antibacterial and placebo mouthwash, respectively. On the fourth day their basal metabolic rate (BMR) was measured with an indirect calorimetric system. Moreover, samples from saliva, urine and blood were collected but these results are not included in this thesis. An earlier, unpublished study has demonstrated that nitrate administration reduces the basal metabolic rate. Accordingly, our aim was to study potential effects on the basal metabolic rate following reduction of the number of oral bacteria by aid of antibacterial mouthwash. Our hypothesis was that the reduced availability of nitrite would decrease the availability of NO in the body and manifest as an increased basal metabolic rate. The results from indirect calorimetry measurements showed no significant difference between placebo and antibacterial mouthwash, but there may be confounding factors. Further study is needed to assess the potential effects on host metabolism by these bacteria.

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Mpongwana, Ncumisa. "Metabolic network modelling of nitrification and denitrification under cyanogenic conditions." Thesis, Cape Peninsula University of Technology, 2019. http://hdl.handle.net/20.500.11838/2982.

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Thesis (PhD (Chemical Engineering))--Cape Peninsula University of Technology, 2019
Simultaneous nitrification and aerobic denitrification (SNaD) is a preferred method for single stage total nitrogen (TN) removal, which was recently proposed to improve wastewater treatment plant design. However, SNaD processes are prone to inhibition by toxicant loading with free cyanide (CN-) possessing the highest inhibitory effect on such processes, rendering these processes ineffective. Despite the best efforts of regulators to limit toxicant disposal into municipal wastewater sewage systems (MWSSs), free cyanide (CN-) still enters MWSSs through various pathways; hence, it has been suggested that CN- resistant or tolerant microorganisms be utilized for processes such as SNaD. To mitigate toxicant loading, organisms in SNaD have been observed to adopt a multiphase growth strategy to sequentially degrade CN- during primary growth and subsequently degrade TN during the secondary growth phase. However, CN- degrading microorganisms are not widely used for SNaD in MWSSs due to the inadequate application of suitable microorganisms (Chromobacterium violaceum, Pseudomonas aeruginosa, Thiobacillus denitrificans, Rhodospirillum palustris, Klebsiella pneumoniae, and Alcaligenes faecalis) commonly used in single-stage SNaD. The use of CN- degrading or resistant microorganisms for SNaD is a cost-effective method compared to the use of other methods of CN- removal prior to TN removal, as they involve multi-stage systems (as currently observed in MWSSs). The use of CN- degrading microorganisms, particularly when used as a consortium, presents a promising and sustainable resolution to mitigate inhibitory effects of CN- in SNaD. However, SNaD is known to be completely inhibited by CN- thus it is imperative to also study some thermodynamic parameters of SNaD under high CN- conditions to see the feasibility of the process. The Gibbs free energy is significant to understand the feasibility of SNaD, it is also vital to study Gibbs free energy to determine whether or not the biological reaction is plausible. The relationship between the rate of nitrification and Gibbs free energy was also investigated. The attained results showed that up to 37.55 mg CN-/L did not have an effect on SNaD. The consortia degraded CN- and achieved SNaD, with degradation efficiency of 92.9 and 97.7% while the degradation rate of 0.0234 and 0.139 mg/L/hr for ammonium-nitrogen (NH4-N) and CN- respectively. Moreover, all the free Gibbs energy was describing the individual processes were found to be negative, with the lowest Gibbs free energy being -756.4 and -1830.9 Kcal/mol for nitritation and nitratation in the first 48 h of the biological, reaction respectively. Additionally, a linear relationship between the rate of NH4-N and nitrite-nitrogen (NO2-N) degradation with their respective Gibbs free energy was observed. Linear model was also used to predict the relationship between NH4-N, NO2-N degradation and Gibbs free energy. These results obtained showed a good correlation between the models and the experimental data with correlation efficiency being 0.94 and 0.93 for nitritation, and nitratation, respectively. From the results found it can be deduced that SNaD is plausible under high cyanide conditions when cyanide degrading or tolerant microorganisms are employed. This can be a sustainable solution to SNaD inhibition by CN- compounds during wastewater treatment. Furthermore, a single strain was purified from the consortium and identified as Acinetobacter courvalinii. This bacterial strain was found to be able to perform sequential CN- degradation, and SNaD; an ability associated with multiphase growth strategy of the microorganism when provided with multiple nitrogenous sources, i.e. CN- and TN. The effect of CN- on nitrification and aerobic denitrification including enzyme expression, activity and protein functionality of Acinetobacter courvalinii was investigated. It was found that CN- concentration of up to 5.8 mg CN-/L did not affect the growth of Acinetobacter courvalinii. In cultures whereby the A. courvalinii isolate was used, degradation rates of CN- and NH4-N were found to be 2.2 mg CN-/L/h and 0.40 mg NH4-N/L/h, respectively. Moreover, the effect of CN- on NH4-N, nitrate-nitrogen (NO3-N) and NO2-N oxidizing enzymes was investigated, with findings indicating CN- did not affect the expression and activity of ammonia monooxygenase (AMO), but affected the activity of nitrate reductase (NaR) and nitrite reductase (NiR). Nevertheless, a slow decrease in NO2-N was observed after the addition of CN- thus confirming the activity of NaR and the activation of the denitrification pathway by the CN-. Moreover, five models’ (Monod, Moser, Rate law, Haldane, and Andrew’s model) ability to predict SNaD under CN- conditions, indicated that only Rate law, Haldane and Andrew’s models, were suited to predict both SNaD and CN- degradation. Due to low degradation rates of NH4-N and CN-, optimization of SNaD was essential. Therefore, response surface methodology was used to optimize the SNaD under CN- conditions. The physiological parameters that were considered for optimization were temperature and pH; with the result showing that the optimum for pH and temperature was 6.5 and 36.5oC respectively, with NH4-N and CN- degradation efficiency of 50 and 80.2%, respectively. Furthermore, the degradation kinetics of NH4-N and CN- were also studied under the optimum conditions in batch culture reactors, and the results showed that up to 70.6% and 97.3% of NH4-N and CN- were simultaneously degraded with degradation rates of 0.66 and 0.41 mg/L/h, respectively. The predictive ability of RSM was further compared with cybernetic models, and cybernetic models were found to better predict SNaD under CN- conditions. These results exhibited a promising solution in the management of inhibition effected of CN- towards SNaD at an industrial scale.

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Camargos, Liliane Santos de. "Alterações no metabolismo de compostos nitrogenados em Calopogonium mucunoides em resposta a diferentes fontes de nitrogênio : efeitos na nodulação e na fixação." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315648.

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Orientador: Ladaslav Sodek
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-09T07:22:51Z (GMT). No. of bitstreams: 1 Camargos_LilianeSantosde_D.pdf: 771179 bytes, checksum: daa7e6be4a51704bd9baabb7c6975f09 (MD5) Previous issue date: 2007
Resumo: Calopogonium mucunoides é uma leguminosa tropical típica de cerrado, sendo muito utilizada em adubação verde e como forrageira. Possui alta capacidade de fixação de nitrogênio, sendo cultivada em solos de baixo pH e pouca fertilidade; e boa resistência à seca, mas não tolera baixas temperaturas. Poucos são os estudos acerca do metabolismo de nitrogênio nesta espécie, mas demonstram que a leguminosa apresenta alta abundância relativa de ureídeos quando fixando nitrogênio. Estudos preliminares nossos demonstraram certa tolerância do mecanismo de fixação à exposição ao nitrato. Este trabalho objetivou estudar o metabolismo de nitrogênio, em Calopogonium mucunoides, identificando as principais alterações no metabolismo de nitrogênio sob diferentes condições de obtenção deste nutriente: plantas cultivadas recebendo solução nutritiva com diferentes fontes de nitrogênio antes da nodulação; e plantas plenamente noduladas, então expostas a receber solução nutritiva com diferentes fontes de nitrogênio, em diferentes concentrações e por diferentes tempos de exposição. Observou-se que a espécie não apresentou nodulação sensível à presença de nitrogênio no meio e, quando plantas plenamente noduladas foram expostas ao nitrogênio, a fixação foi mantida e a atividade da enzima nitrogenase só foi afetada, embora não totalmente, quando as plantas foram expostas a concentrações de 30 mM de nitrato. Por outro lado, a espécie parece responder à fonte de nitrogênio translocando e/ou acumulando diferentes formas de ureídeo (alantoína e ácido alantóico), mas o metabolismo de aminoácidos não apresentou resposta padrão à exposição ao nitrogênio. Estes estudos indicaram tolerância da nodulação e da fixação de nitrogênio desta espécie ao cultivo na presença de nitrogênio, podendo então servir de embasamento a futuros estudos acerca da sensibilidade/tolerância desses processos à presença de nitrogênio no meio em leguminosas em geral
Abstract: Calopogonium mucunoides is a tropical legume found in the ¿cerrado¿ (savanna) regions, and widely used as green manure and forage. It has a high capacity for fixing nitrogen, being cultivated in soils with low pH and poor fertility; and good resistance to drought, but does not tolerate low temperatures. Studies on the nitrogen metabolism of this species are quite scarce but it is known that the legume has a high relative abundance of ureides when fixing nitrogen. Our own preliminary studies suggested certain tolerance of fixation to the presence of nitrate. The objective of the present study was to study nitrogen metabolism in Calopogonium mucunoides, identifying the influence of the nitrogen source on nitrogen metabolism using: different nitrogen sources starting before nodulation; and exposing plants to the same sources only after complete nodulation, at different concentrations and times of exposure. It was found that the nodulation process of this species was not sensitive to the presence of a nitrogen source in the medium and, when fully nodulated plants were exposed to the nitrogen sources, fixation was maintained and the activity of nitrogenase was only affected, albeit partially, when exposed to the highest (30 mM) dose of nitrate. On the other hand, the species appears to respond to the exogenous source of nitrogen by translocating and/or accumulating different forms of ureides (allantoin and allantoic acid), but the metabolism of amino acids did not respond clearly to the nitrogen source. The data indicate that the process of nodulation and nitrogen fixation in this species is tolerant to the presence of a nitrogen source in the medium and should prove useful for future studies on the sensitivity/tolerance of nitrogen fixation to na external nitrogen source in legumes
Doutorado
Doutor em Biologia Vegetal

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Poucet, Théo. "The energy cost of primary metabolism and vacuole expansion : Central to shape tomato leaf development under ammonium nutrition." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0079.

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L'ammonium (NH4+) est une source d'azote d'un grand intérêt dans le cadre d'une agriculture durable. Son application en champs avec des inhibiteurs de nitrification s’est montré efficace pour limiter les pertes de N par rapport à l'utilisation de nitrate (NO3-). NH4+ est un intermédiaire commun impliqué dans de nombreuses voies métaboliques. Cependant, des concentrations élevées peuvent conduire à une situation de stress chez la plante provoquant un « syndrome ammoniacal », caractérisé par une croissance réduite. Ces symptômes sont causés par la combinaison, entre autres, d'une reprogrammation métabolique, d'une perturbation de la photosynthèse, d'une dérégulation du pH et d'un déséquilibre ionique. De nombreuses études ont décrit la façon dont la plante s’adapte à la nutrition ammoniacale. Cependant, le stade de développement des organes a été souvent négligé.Pour combler cette lacune, dans le premier chapitre nous étudions comment le métabolisme s’adapte en fonction de la position des feuilles sur l'axe vertical de plants de tomates (Solanum lycopersicum) cultivées en présence de NH4+, NO3- ou NO3NH4. Nous avons disséqué la composition de la biomasse foliaire et le métabolisme grâce à une analyse complète des métabolites, ions et activités enzymatiques. Nos résultats montrent que l'ajustement métabolique du C et du N en fonction de la source d'azote était plus intense chez les feuilles âgées par rapport au plus jeunes. Surtout, nous révélons un compromis entre l'accumulation de NH4+ et l'assimilation afin de préserver les jeunes feuilles du stress ammoniacal. Par ailleurs, les plantes alimentées en NH4+ présentaient un réarrangement des squelettes carbonés impliquant un coût énergétique élevé. Nous expliquons une telle réallocation par l'action du pH-stat biochimique, pour compenser la production différentielle de protons dépendante de la forme azotée fournie.La nutrition ammoniacale peut limiter l'expansion cellulaire. Entre autres, la croissance cellulaire dépend largement de la pression interne exercée par la vacuole sur la paroi cellulaire. Cependant, l’impact du stress ammoniacal sur la vacuole a été rarement abordé. Dans le second chapitre, nous évaluons l'effet de la nutrition ammoniacale sur le développement des feuilles en se focalisant sur l'expansion et le métabolisme vacuolaire. Pour cela, nous avons suivi le développement d’une feuille depuis son apparition jusqu'à son expansion complète avec du NH4+ ou NO3- comme seule source d'azote. Nous avons d’abord mis en évidence que la réduction de l’expansion cellulaire en nutrition ammoniacal était associée à des vacuole plus petite et aussi plus acide que celles recevant du NO3-. De plus, un modèle a été construit pour prédire l'équilibre thermodynamique de différentes espèces solubles de part et d’autre du tonoplaste. Le modèle intègre les volumes subcellulaires, les gradients électrochimiques et la formation de complexe ionique dans la vacuole afin de prédire les concentrations subcellulaires des ions, acides organiques et sucres mesurée dans la feuille. De plus, ces prédictions ont été validées avec des données obtenus par fractionnement non aqueux. Finalement, l’estimation des flux de soluté dans la vacuole nous a permis de démontrer que la déficience en malate dans les cellules des feuilles nourries avec NH4+ est central dans la limitation de l'expansion vacuolaire. De plus, nous concluons que le coût énergétique du transport de soluté dans la vacuole est plus élevé sous nutrition ammoniacale en raison du gradient électrochimique plus élevé généré de part et d’autre du tonoplaste. Ce travail souligne l'importance de considérer l'état phénologique des feuilles lors de l'étude du métabolisme de l'azote. De plus, notre approche place le contrôle du pH cytosolique et l'expansion des vacuoles au centre de l'adaptation des feuilles de tomate à ce stress et ouvre la voie à de futures études dans le domaine de la nutrition ammoniacal
Ammonium (NH4+) is a nitrogen source of great interest in the context of sustainable agriculture. Its application in the field together with nitrification inhibitors has been extensively proven efficient to limit detrimental N losses compared to the use of nitrate (NO3-). NH4+ is a common intermediate involved in numerous metabolic routes. However, high NH4+ concentrations may lead to a stress situation provoking a set of symptoms collectively known as “ammonium syndrome” mainly characterized by growth retardation. Those symptoms are caused by a combination of, among others, a profound metabolic reprogramming, disruption of photosynthesis, pH deregulation and ion imbalance. Numerous studies have described the way plant copes to ammonium nutrition. However, the organ developmental stage has been generally neglected.To fill in this gap, in the first chapter we first aimed studying how the metabolism is adapted in function of the leaf position in the vertical axis of the tomato plants (Solanum lycopersicum) grown with NH4+, NO3- or NO3NH4 supply. To do so, we dissected leaf biomass composition and metabolism through a complete analysis of metabolites, ions and enzyme activities. The results showed that C and N metabolic adjustment in function of the nitrogen source was more intense in older leaves compared to younger ones. Importantly, we propose a trade-off between NH4+ accumulation and assimilation to preserve young leaves from ammonium stress. Besides, NH4+-fed plants exhibited a rearrangement of carbon skeletons with a higher energy cost respect to plants supplied with NO3-. We explain such reallocation by the action of the biochemical pH-stat, to compensate the differential proton production that depends on the nitrogen form provided.Ammonium nutrition may limit cell expansion, suggesting that the cellular processes involved would be altered. Among others, cell growth is largely dependent of the internal pressure exerted on the cell wall by the vacuole. However, the role of the vacuole in ammonium stress has been rarely addressed. In the second chapter, we evaluated the effect of ammonium stress on leaf development with a special focus on vacuole expansion and metabolism. To carry out this aim, we monitored the leaf development from its appearance until its complete expansion in plants grown under NH4+ or NO3- as unique nitrogen source. Cytological analysis evidenced that the reduced cell expansion under ammonium nutrition was associated with smaller vacuole size. Besides, we reported an acidification of the vacuole of NH4+-fed plants compared to nitrate nutrition. Moreover, a model was built to predict the thermodynamic equilibrium of different soluble species across the tonoplast. The model was set up through an extensive reviewing of vacuolar transporters and integrated subcellular volumes, vacuolar electrochemical gradients and the formation of ionic complex in the vacuole to fit the subcellular concentration of ions, organic acids and sugars measured in the leaf. Further, predictions obtained with the model were cross validated with data from non-aqueous fractionation. Firstly, the entrance of solutes was higher in vacuoles of NO3--fed leaves but was not associated with higher vacuolar osmolarity likely because of the adjustment of the vacuolar volume. In this sense, we proposed that the lack of malate in cells of ammonium-fed leaves was central in the limitation of vacuolar expansion. Secondly, we conclude that the energy cost of solute transport into the vacuole is higher under NH4+ nutrition because of the higher electrochemical gradient generated by the proton pumps across tonoplast.This work highlights the importance of considering leaf phenological state when studying nitrogen metabolism. In addition, our integrated approach place cytosolic pH control and vacuole expansion in the center of tomato leaf adaptation to ammonium stress and pave the way for future studies in the field of ammonium nutrition

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Pereira, Paula Natália. "Divisão espacial da atividade das enzimas PEPC e da NR e sua regulação por citocininas em folhas de Guzmania monostachia induzidas ao CAM." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/41/41132/tde-19122012-215637/.

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Estudos anteriores realizados no Laboratório de Fisiologia Vegetal do IBUSP com Guzmania monostachia demonstraram que quando essas plantas são submetidas ao déficit hídrico ocorre a indução do CAM, com maior expressão desse metabolismo na porção foliar apical. Para outra espécie (Vriesea gigantea), foi verificada a maior atividade da enzima nitrato redutase (NR) na porção basal durante o período diurno. Em uma bromélia terrestre (Ananas comosus) foi observada a sinalização por citocininas tanto na indução da expressão gênica, quanto na ativação da NR. Outros laboratórios evidenciaram que plantas de Mesembryanthemum crystallinum induzidas ao CAM apresentaram uma provável regulação negativa da fosfoenolpiruvato carboxilase (PEPC) por citocininas. Em decorrência desses conhecimentos acumulados, surgiram novos questionamentos: haveria variações diuturnas da atividade das enzimas PEPC e NR nas diferentes porções das folhas de G. monostachia induzidas ao CAM? A maior disponibilidade de esqueletos carbônicos à noite (acúmulo de acidez) influenciaria positivamente a atividade da NR, deslocando seu pico de atividade para o período noturno? As variações dos teores endógenos de citocininas acompanhariam as possíveis mudanças da atividade da PEPC e da NR, indicando, assim, a participação dessa classe hormonal na regulação dessas enzimas? O presente trabalho teve por objetivo principal investigar uma possível regulação da atividade das enzimas PEPC e NR por citocininas em folhas destacadas da bromélia epífita com tanque, Guzmania monostachia (Bromeliaceae) induzidas ao CAM. Foi esperado com esta pesquisa aprofundar os estudos sobre a inter-relação entre o comportamento fotossintético, a capacidade de assimilação de nitrogênio e a possível regulação das atividades da PEPC e da NR por citocininas endógenas. Análises de acidez titulável, ácidos orgânicos, amido endógeno e da atividade da enzima malato desidrogenase (MDH) foram realizadas, confirmando a indução do CAM nas folhas isoladas de G. monostachia mantidas em polietilenoglicol (PEG) a uma concentração de 30%. O uso desse composto foi eficiente na redução do conteúdo relativo de água e na imposição da deficiência hídrica foliar. Além disso, pôde-se verificar a maior expressão do CAM na porção apical das folhas mantidas em PEG 30%, quando comparada à porção basal. Análises da atividade da PEPC e da NR permitiram verificar a separação espacial dessas enzimas. A primeira apresentou maior atividade no ápice foliar, enquanto a segunda mostrou a maior atividade na porção basal. Apesar disso, não foi observada a separação temporal dessas enzimas, uma vez que ambas apresentaram picos de atividade noturna. A maior atividade da NR durante o período escuro (01 hora) foi verificada nas folhas-controle ou sob deficiência hídrica. Esse resultado sugere que outros fatores, diferentes do metabolismo CAM, influenciaram para a ocorrência da maior atividade dessa enzima durante o período noturno. Os resultados obtidos ainda sugerem que as citocininas possivelmente atuaram como um regulador negativo para a atividade da PEPC durante o dia, uma vez que os maiores níveis endógenos desse hormônio foram observados durante esse período, enquanto a maior atividade dessa enzima foi verificada durante a noite, quando os teores de Z+iP decaíram significativamente. A aplicação de Z ou iP resultou também num decréscimo da atividade dessa enzima. Por outro lado, as citocininas atuaram como um provável regulador positivo para a atividade da NR, uma vez que a maior atividade noturna dessa enzima foi antecedida em 3 ou 6 horas pelos maiores níveis endógenos de citocininas na porção basal das folhas mantidas em água ou PEG 30%, respectivamente. A aplicação de citocininas-livres aumentou significativamente a atividade da NR na base das folhas destacadas mantidas em água ou PEG 30%
Prior studies undertaken in the Laboratory of Plant Physiology on IBUSP with Guzmania monostachia have shown that during water shortage, CAM induction occurs with greater expression in the apical portion of the leaf. In the case of another species (Vriesea gigantean), more intense nitrate reductase (NR) enzyme activity was observed in the basal portion during the daytime. In a certain terrestrial bromeliad (Ananas comosus), signaling by cytokinins, both in the induction of gene expression as well as NR activation, was observed. According to other laboratories, the cytokinins seem to play a negative regulation of phosphoenolpyruvate carboxylase (PEPC) in CAM induced Mesembryanthemum crystallinum plants. As a result of accumulated knowledge, new questions have arisen, such as: Are there daily variations in PEPC and NR enzymes activity in the different portions of CAM induced leaves of G. monostachia? Would the more pronounced nocturnal availability of carbon skeletons (accumulation of acidity) positively influence NR activity, with consequential displacement of its peak of activity to this period? Would variations in endogenous cytokinins concentration accompany possible changes in PEPC and NR activity, thereby indicating the participation of this hormonal class in their regulation? The main aim in the present study was to investigate the possible regulation of PEPC and NR activity by cytokinins in detached CAM-induced leaves of the epiphyte tank bromeliad Guzmania monostachia (Bromeliaceae). The expectations with this research were to study more deeply the inter-relationship between photosynthetic behavior, the capacity for nitrogen assimilation and the possible regulation of PEPC and NR activity by endogenous cytokinins. Analyses of titratable acidity, organic acids, endogenous starch and malate dehydrogenase (MDH) enzyme activity confirmed CAM induction in isolated leaves of G. monostachia kept in polyethylene glycol (PEG) at a concentration of 30%. The use of this compound was efficient in reducing relative water content and imposing leaf water deficiency. Furthermore, compared to the basal portion, greater CAM expression could be observed in the apical portion of leaves kept in PEG 30%. Analyses of PEPC and NR activity allowed detecting their mutual spatial separation, seeing that, in the first greater activity was concentrated in the leaf apex, while in the second this was more pronounced in the basal portion. Even so, no temporal separation could be observed, since peak of activity for both occurred at night. The peak of nocturnal NR activity (1 hour) was observed in control leaves or those undergoing water deficiency, thereby implying that factors, other than CAM metabolism, exerted an influence on the occurrence of more intense activity of this enzyme at this time. Furthermore, there were indications that cytokinins possibly act as a negative regulator of PEPC activity during the daytime, when the highest endogenous levels of this hormone were observed, whereas it was apparent that the most intense activity of this enzyme actually occurred at night, when Z+iP rates decreased significantly. Z or iP application also induced a decrease in the activity of this enzyme. On the other hand, the cytokinins acted as a positive regulator of NR activity, since the nocturnal peak of activity of this enzyme was preceded by 3 or 6 hours by higher endogenous levels of cytokinins in the basal portion of leaves maintained in water or PEG 30%, respectively. The application of free cytokinins induced a significant increase in NR activity in the base of detached leaves kept in water or PEG 30%

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Neto, Ana Paula. "Metabolismo do nitrogênio e concentração de nutrientes no cafeeiro irrigado em razão da dose de N." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/11/11136/tde-18022010-140953/.

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A adubação nitrogenada e sua implicação no metabolismo do cafeeiro ainda não são bem conhecidas nas condições de campo, em cafeicultura altamente tecnificada, com temperatura média de outono-inverno superior a 22 ºC e maior quantidade de horas-luz. O objetivo da presente pesquisa foi avaliar a atividade das enzimas redutase do nitrato (RN), glutamina sintetase (GS) e urease em função da dose de nitrogênio (sem N, 200, 400, 600 e 800 kg ha-1). Avaliou-se também a influência das doses de N (uréia) nas concentrações de N-total, nitrato, amônio, clorofila e carotenóides presentes nas folhas; as flutuações de macro e micronutrientes; bem como a correlação entre a produtividade e doses de N. Objetivou-se também identificar a época do pico da atividade da RN. Os experimentos foram realizados no Oeste baiano e em Piracicaba, SP. As avaliações foram realizadas nas fases fenológicas: vegetação, antese, fruto chumbinho, granação e maturação. A maior atividade da RN ocorreu com o fornecimento de 800 kg ha-1 de N, sem variação nas demais doses, bem como não influenciou a atividade da GS e urease. As concentrações de nitrato e amônio não aumentaram com as doses de N, mas a concentração de aminoácidos foi crescente com a dose do nutriente. A maior atividade da RN verificou-se na fase de vegetação e granação dos frutos, a qual foi superior às 12:00 h, enquanto as atividades da GS e urease foram superiores na fase de granação dos frutos. A maior concentração de nitrato se deu entre a fase de fruto chumbinho e início da granação e do amônio no final da granação. O pico da atividade da RN aconteceu aos 25 dias após a adubação nitrogenada. O uso de altas doses de N não prejudicou a concentração de macro e micronutrientes foliar. Finalmente, a máxima produtividade do cafeeiro foi obtida com a aplicação de 400 kg ha-1 de N.
The nitrogen fertilization and its implication in the nitrogen metabolism of coffee plants are not well known in high technology production under field conditions with autumn-winter average temperatures above 22 º C and a larger photoperiod. The objective of this work was to evaluate the nitrate reductase, glutamine synthetase and urease activity due to nitrogen fertilization rates (without N, 200, 400, 600 e 800 kg ha-1). In the present work was evaluated also the influence of nitrogen rates on total nitrogen, nitrate, ammonium, chlorophylls and carotenoids concentration in the leaves, the variation of macro and micronutrients as well as the correlationship between coffee yield and nitrogen fertilization rates. Moreover, the goal of this study was to identify the period of peak activity of nitrate reductase. The experiment was carried out at western of Bahia State and Piracicaba, State of Sao Paulo, Brazil. The periods of evaluations were plant growth, anthesis, pin head fruits, filling and maturation fruits stage development. The highest nitrate reductase activity occurred with 800 kg ha-1 N supply and no changes on this enzyme were observed regarding other rates. Therefore, the nitrogen rates did not affect the glutamine synthetase and urease activity. The nitrate and ammonium concentration did not increase with nitrogen rates; however, the aminoacids concentration increased due to nitrogen fertilization rates. The highest activity of nitrate reductase was observed at 12:00h during plant growth and filling fruits stage development. On the other hand, the higher activity of glutamine synthetase and urease were during filling fruits stage. The highest nitrate concentration was detected during between pin head and beginning of filling fruits stage, and the highest ammonium concentration was during end of filling fruits stage development. The peak activity of nitrate reductase was 25 days after nitrogen fertilization. The high nitrogen rates did not affect the macro and micronutrients concentration in the leaves. The greater coffee yield was provided with 400kg ha-1 of nitrogen supply.

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Antunes, Flavia. "Papel da redutase do nitrato e da asparagina sintetase em plantas de soja (Glycine max L.) sob condições de estresse de nitrogenio." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315227.

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Orientador: Ladaslav Sodek
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: O sistema radicular da soja (Glycine max L.) é um importante sítio da assimilação do nitrogênio (N), seja pela assimilação do nitrato nas raízes, seja pela fixação simbiótica de N atmosférico nos nódulos. Os principais produtos da assimilação do N inorgânico, os aminoácidos asparagina e glutamina, os ureídeos, a alantoína e o ácido alantóico, são usados no transporte de N para a parte aérea. Assim, esses produtos representam uma fonte de N reduzido tanto para os sítios de consumo, quanto para a formação de outros aminoácidos, proteínas, ácidos nucléicos e dos demais compostos nitrogenados sintetizados na célula. O transporte do N assimilado no sistema radicular para a parte aérea é realizado exclusivamente via xilema. Portanto, o objetivo geral deste trabalho foi, relacionar mudanças na composição de aminoácidos transportados no xilema de plantas de soja, provocadas pela deficiência de N, com o comportamento de enzimas de assimilação do N, encontradas no sistema radicular. Para causar a deficiência do N, as plantas de soja foram transferidas para um meio hidropônico sem nitrato ou qualquer outra fonte de N inorgânico. Nas plantas não-noduladas a deficiência se deu pela ausência do nitrato no meio de cultivo, e nas plantas noduladas, a manutenção em hidroponia inibiu a fixação do N2. Foi observado um aumento na razão aspartato/asparagina (ASP/ ASN) na seiva do xilema das plantas não-noduladas e noduladas, quando foram submetidas à deficiência do N. Contudo, nas plantas noduladas esse aumento foi acentuado apenas no primeiro dia do tratamento. A recuperação do estresse só ocorreu em plantas não-noduladas, nas quais as concentrações de ASP e ASN retomaram seus valores. As análises da expressão dos genes que codificam a asparagina sintetase (AS) no sistema radicular das plantas de soja, durante o , leva à uma diminuição dos níveis de glutamina, produto imediato da assimilação do íon amônio através da enzima glutamina sintetase (GS). Com a redução dos níveis de glutamina a atividade da AS também é reduzida, resultando na menor utilização de ASP. Em plantas não-noduladas, após transferência para o meio hidropônico sem nitrato, a expressão dos três genes para AS diminuiu bruscamente, e após o retorno das plantas ao meio com nitrato, os genes da AS foram expressos novamente. Nas plantas noduladas a expressão gênica da AS também reduziu durante o tratamento de deficiência de N, porém, apenas o gene SAS1 parece ter sido afetado. O gene SAS1 não recuperou seus níveis de expressão durante a tentativa de recuperação do estresse. Este fato é mais uma evidência da relação da AS com as alterações no perfil de aminoácidos transportados na seiva do xilema, pois as concentrações de ASN e ASP na seiva do xilema também não foram retomadas. tratamento e recuperação do estresse de N, indicam que essa enzima está relacionada com as alterações na razão ASP/ASN. A AS é a enzima que catalisa a biossíntese da ASN, transferindo o grupo amino da glutamina para o aspartato, produzindo asparagina e glutamato. A queda no suprimento de N, seja pelo impedimento da assimilação do nitrato ou da fixação do N2. Devido à importância da enzima redutase do nitrato (RN) no processo de assimilação do nitrato pelo sistema radicular, foi avaliado o seu comportamento durante o tratamento de deficiência do nitrato e sua recuperação. A atividade da RN aumentou, consideravelmente, quando as plantas foram expostas ao nitrato. Esse aumento pôde ser observado em raízes de plantas de soja não-noduladas e também no sistema radicular (raízes e nódulos) das plantas noduladas. Quando as plantas não-noduladas foram transferidas para uma solução sem nitrato, a atividade da RN caiu, apresentando valores muito baixos dentro de 24 horas. As atividades da RN ) parece bastante clara. De qualquer forma, a forte dependência da RN da presença do nitrato é um dado inédito para raízes de plantas de soja. O nitrato também afetou a expressão gênica da AS nas raízes de plantas noduladas, cultivadas sem nenhuma fonte de N mineral. A expressão dos genes da AS aumentou quando essas plantas receberam solução contendo nitrato. nas raízes e nódulos de plantas de soja, cultivadas na ausência do nitrato, foram muito baixas, sendo que em nódulos a atividade sempre foi ligeiramente maior que nas raízes. A baixa atividade encontrada nas raízes e nódulos de soja pode representar a forma constitutiva da enzima, pois as plantas foram cultivadas sem a adição do nitrato durante o ciclo todo. Entretanto, não pode ser descartada a possibilidade da presença de traços de nitrato na água usada para regar as plantas e isto ter sido suficiente para induzir a baixa atividade encontrada. Se por um lado podem existir dúvidas quanto ao fato da enzima ser constitutiva, a indução da enzima pelo substrato (NO3- Os dados sobre o comportamento das enzimas avaliadas aqui indicam que as alterações em aminoácidos transportados no xilema, em plantas de soja submetidas à deficiência de N, estão relacionadas com os processos assimilatórios do sistema radicular, e que a AS parece ser a principal responsável pelas alterações na razão ASP/ASN
Abstract: The root system of soybean (Glycine max L.) is an important site for the assimilation of nitrogen, whether by nitrate assimilation in the roots, or by symbiotic nitrogen fixation in the nodules. The main products of inorganic nitrogen assimilation, the amino acids asparagine and glutamine and the ureides allantoin and allantoic acid, are used in the transport of assimilated nitrogen to the shoot. Thereby, these products represent a source of reduced nitrogen for the sink tissues, for the formation of other amino acids, proteins, nucleic acids and all the other nitrogenous compounds synthesized in the cell. Therefore, the objective of this study was to relate changes in the transport of nitrogen in the xylem of soybean caused by nitrogen deficiency with the behaviour of certain enzymes of nitrogen assimilation in the root system. Nitrogen deficiency was induced by the transfer of soybean plants to a hydroponic system without nitrate or any other source of inorganic nitrogen. In the case of non-nodulated plants deficiency was imposed by the interruption of nitrate assimilation by the roots, and for the nodulated plants nitrogen fixation was inhibited by immersion of the nodules in the hydroponic system. Under nitrogen deficiency, an increase in the aspartate/asparagine (ASP/ASN) ratio of the xylem sap was observed in both nodulated and non-nodulated plants. Nevertheless, this increase was substantial only on the first day of treatment. The recovery from the stress was only observed for the non-nodulated plants, where the levels of ASP and ASN returned to their initial values. Analyses of asparagine synthetase expression in the root system of soybean during treatment and recovery from nitrogen stress indicates that this enzyme can underlay the changes in ASP/ASN ratios. AS is an enzyme that catalyses the biosynthesis of Asn, by transferring the amide nitrogen from glutamine to aspartate, producing asparagine and glutamate. The fall in N supply, whether by interruption of nitrate assimilation or nitrogen fixation, leads to a decline in glutamine, the immediate product of ammonium ion assimilation via glutamine synthetase. With the reduction in glutamine levels the activity of AS is also reduced resulting in diminished utilization of ASP. In non-nodulated plants, after the transfer to the hydroponic system without nitrate, the expression of the three genes declines sharply, and after the return of the plants to a supply of nitrate the AS genes are expression again. In nodulated plants the expression of AS was also reduced during treatment, however, in this case only the gene SAS1 was affected. The SAS1 gene did not recover its initial levels of expression after removing the stress which is further evidence for the correlation between AS activity and the changes in ASP/ASN ratios in the xylem sap, since these ratios were also not recovered. In view of the importance of nitrate reductase (NR) in the process of nitrate assimilation by the root system, its behaviour was evaluated during nitrate deficiency and recovery. The activity of NR increased considerably when plants were supplied with nitrate, in the case of roots of non-nodulated as well as the root system (roots and nodules) of nodulated plants. When non-nodulated plants were transferred to a nutrient solution free of nitrate, NR activity fell sharply, almost disappearing within 24 hours. RN activities in roots and nodules of soybean grown in the absence of nitrate were very low, with activity in the nodules being somewhat higher than in the roots. The low activity found in the roots and nodules could be due to a constitutive enzyme since plants were grown throughout with nitrate-free medium. However, the possible presence of trace amounts of nitrate in the tap water used to irrigate the plants cannot be discarded and may have been sufficient to induce the low levels of enzyme found. If on the one hand there are doubts as to the presence of a constitutive enzyme, the presence of the induced form is very clear. In any case, the strong dependence of NR on the presence of nitrate is an unknown fact for soybean roots. Nitrate also affected the expression of AS in roots of nodulated plants grown without any mineral source of nitrogen, since its expression increased tremendously when such plants were supplied with nitrate. The data concerning the behaviour of the enzymes studied here indicate that alterations in xylem amino acids of soybean plants subjected to nitrogen deficiency are related to the assimilatory processes of the root system, and that AS appears to be mainly responsible for the changes in ASP/ASN ratios
Doutorado
Biologia Vegetal
Doutor em Biologia Vegetal

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Packer, Philip James. "The metabolism and pharmacology of nitrate in relation to human cancer." Thesis, Open University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328929.

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Zafrilla, Basilio. "Expresión recombinante de proteínas relacionadas con el metabolismo del nitrógeno en Haloferax mediterranei." Doctoral thesis, Universidad de Alicante, 2011. http://hdl.handle.net/10045/21504.

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Presnell, Steven Ray. "Purification, stabilization, and crystallization attempts of a mutant form of endothelial nitric oxide synthase." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/31040.

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Rebelo, Lucas Rocha [UNESP]. "Influência de nitrato encapsulado e enxofre na dieta sobre metabolismo e emissão de metano em bovinos." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/151072.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Este estudo objetivou avaliar o efeito da substituição da fonte de proteína verdadeira e da ureia por nitrato encapsulado (En) e enxofre (S) elementar sobre consumo, digestibilidade, parâmetros ruminais, eficiência de síntese de proteína microbiana e emissão de CH4 em bovinos Nelore. Foram utilizados cinco novilhos Nelore (352.7 ± 38.4 kg PV) canulados no rumen, e distribuídos em um delineamento em quadrado latino 5 × 5 (5 tratamentos e 5 períodos, 21 dias cada). O volumoso utilizado foi feno de Tifton 85 e o concentrado basal foi composto por milho, farelo de soja, e suplemento mineral comercial. Ureia, En e S foram adicionados para compor demais dietas. Os tratamentos foram: farelo de soja (SBM) como tratamento controle; ureia (U); U mais S elementar (US); nitrato encapsulado (EN); e EN mais S elementar (ENS). O En foi incluído nos tratamentos EN e ENS em 2% da MS (1,42% de NO3 - ânion), enquanto que a inclusão de ureia nos tratamentos U e US foi de 0,8% na MS da dieta. A inclusão de S nos tratamentos U e EN foi em 0,24% da MS, e a relação N:S foi reduzida de 8:1 para 4:1 com a adição de S. O En foi incluído gradualmente de 0,5% até 2% da MS da dieta. Os contrastes ortogonais para avaliar os efeitos de tratamento foram: SBM vs. EN + ENS; U + US vs. EN + ENS; U vs. US; e EN vs. ENS. Os novilhos apresentaram baixos níveis de MetHb (média de 1,1%) a medida em que a quantidade de En foi aumentada. O consumo de OM e NDF foram menores (P ≤ 0,01) para os animais alimentados com En comparado à SBM. A digestibilidade da DM, OM, e GE foram maiores (P ≤ 0,01) quanto fornecido En comparado à ureia. O pH ruminal foi maior (P = 0,01) e N-NH3 foi menor (P = 0,01) para animais recebendo En na dieta comparado à ureia. Comparado à ureia, o fornecimento de En causou redução (P = 0,01) na proporção de propionato, assim como aumento (P ≤ 0,03) na proporção de acetato e na relação acetato:propionato. O consumo de N foi menor (P ≤ 0,07) em animais alimentados com En comparado à SBM e ureia. O N retido (g N/d) foi menor (P = 0,01) com dietas com En comparado à SBM e ureia. Nitrogênio microbiano (MN; g MN/d) tendeu a aumentar (P = 0,06) com a inclusão de En comparado à SBM, e foi aumentado (P ≤ 0,04) pela adição de S elementar à dietas com NNP. O fornecimento de dietas com En aumentou (P ≤ 0,01) MN quando em proporção à ingestão de PB (CPI; g MN/kg CPI) e aumentou (P = 0,02) a eficiência de síntese de MN com base na ingestão de OM digestível (DOMI; g MN/kg DOMI) comparado à SBM, assim como tendeu a aumentar (P = 0,09) g MN/kg DOMI comparado à ureia. A adição de S elementar às dietas com NNP tendeu a aumentar (P ≥ 0,05) g MN/kg CPI, e aumentou (P = 0,04) g MN/kg DOMI quando incluído na dieta EN. Animais alimentados com En tiveram redução (P = 0,02) na emissão de CH4 em cerca de 31,2 g CH4/d, e tenderam a reduzir (P = 0,06) a emissão de CH4 em g CH4/kg DMI e como % da GEI, quando comparados à SBM. Portanto, En mais S elementar em substituição parcial à proteina verdadeira da ração ou substituindo totalmente a ureia pode otimizar a eficiência de síntese de proteína microbiana e concomitantemente reduzir a emissão de CH4 por bovinos Nelore.
The objective of this study was to investigate the replacement of true protein source as well as the conventional NPN source (urea) by encapsulated NO3 - (En) plus elemental sulfur (S) on microbial protein synthesis efficiency, and CH4 emission in Nellore beef cattle. Five ruminally-cannulated Nellore steers (352.7 ± 38.4 kg BW) were used in a 5 × 5 Latin square design with 5 periods of 21 d each. Tifton 85 hay was used as forage and the basal concentrate consisted of corn, soybean meal, and commercial mineral supplement (50:50 wt/wt, forage:concentrate). Urea, En and S were added to compose the other diets. The treatments were: true protein from soybean meal as control (SBM); urea (U); U plus elemental S (US); encapsulated NO3 - (EN); and EN plus elemental S (ENS). En was included in 2% on dietary DM (1.42% NO3 - anion), while the inclusion of urea in U and US diets was 0.8% on dietary DM. The inclusion of S for U and EN diets was 0.24% on dietary DM, and the N:S ratio was reduced from 8:1 to 4:1 with the addition of S. En was gradually included from 0.5 to 2% on dietary DM by 0.5% every 4 d. The orthogonal contrasts for specific partitioning of treatment effects were: SBM vs. EN + ENS; U + US vs. EN + ENS; U vs. US; and EN vs. ENS. Steers displayed adequate MetHb levels as dietary En content increased. Organic matter and aNDF intake were smaller (P ≤ 0.01) for animals fed En diets compared to SBM. Digestibility of DM, OM, and GE were greater (P ≤ 0.01) when fed En diets compared to urea. Ruminal pH was greater (P = 0.01) and ruminal NH3-N was smaller (P = 0.01) for animals fed En diets compared to urea. Compared to urea, En supply resulted in lower propionate proportion (P = 0.01), but increased (P ≤ 0.03) acetate proportion and acetate:propionate ratio. Nitrogen intake was smaller (P ≤ 0.07) with En supply compared to SBM and urea. Retained N (g N/d) for animals fed En diets was smaller (P = 0.01) compared to SBM and urea. Microbial N (MN; g MN/d) tended to increase (P = 0.06) with En inclusion compared to SBM, and was increased (P ≤ 0.04) by the addition of elemental S to NPN diets. Encapsulated NO3 - diets supply increased (P ≤ 0.01) MN as a proportion of CPI (g MN/kg CPI), increased (P = 0.02) MN efficiency based on digestible OM intake (DOMI; g MN/kg DOMI) compared to SBM, and as well tended to increase (P = 0.09) g MN/kg DOMI compared to urea. The addition of elemental S to NPN diets tended to increase (P ≥ 0.05) g MN/kg CPI, and increased (P = 0.04) g MN/kg DOMI when included in EN. Animals fed En diets decreased (P = 0.02) CH4 emission by 31.2 (g CH4/d), and tended to decrease (P = 0.06) CH4 emission (g CH4/kg DMI, and CH4 as % of GEI) when compared to SBM. Thus, En plus elemental S as a dietary additive replacing part of true protein of the ration or totally urea can optimize microbial protein synthesis efficiency and concomitantly decrease CH4 emission by Nellore beef cattle.
FAPESP: 2016/01562-0

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16

Gray, Travis Michael. "Linking Heterotrophic Metabolism and Nutrient Uptake in Headwater Streams." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/34703.

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Autotrophs and heterotrophs differ in their demand, acquisition and use of materials, but fundamentally nutrient demand is inherently linked to metabolism based on the stoichiometry of biochemical reactions. The differences between these two groups of organisms confound straightforward regression approaches to quantifying the relationship between nutrient demand and metabolism at an ecosystem level. We address how nutrient demand in headwater streams changes with shifts in organic matter supply and associated microbial activity by investigating these relationships in the predominantly heterotrophic conditions of a southern Appalachian stream. We measured litter input, organic matter standing crops, litter respiration rates and nitrate demand several times during the course of decomposition. There was a strong relationship between leaf standing crop and nitrate uptake efficiency across dates with maximal efficiency occurring when litter standing crops were highest. There was also an increase in nitrogen (N) uptake rate relative to respiration rates as breakdown progressed, which appears to be due to a shift in nutrient supply from the substrate to the water column associated with the depletion of labile, high quality organic matter in the substrate. It is our contention that streams establish a gradient of resource supply from particulate to dissolved sources that coincides with the movement of materials from terrestrial to marine systems.
Master of Science

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17

Chen, Fan. "Metabolism of Pseudomonas Aeruginosa Under Simultaneous Aerobic Respiration and Denitrification." University of Akron / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=akron1133809898.

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18

Komeda, Hidenobu. "Organization and Regulation of Genes Involved in Nitrile Metabolism in Rhodococcus rhodochrous J1." Kyoto University, 1996. http://hdl.handle.net/2433/160870.

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本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものである
Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第6519号
農博第895号
新制||農||726(附属図書館)
学位論文||H8||N2948(農学部図書室)
UT51-96-K87
京都大学大学院農学研究科農芸化学専攻
(主査)教授清水昌, 教授駒野徹, 教授加藤暢夫
学位規則第4条第1項該当

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19

Ntessalen, Maria. "The effect of nitrogenous compounds on skeletal muscle metabolism and mitochondrial function." Thesis, University of Aberdeen, 2014. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=228070.

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Nitrate is a progenitor of nitric oxide found in high concentrations in diets rich in fruits and vegetables, such as the Mediterranean. Following enterosalivary circulation, nitrate is converted by salivary bacteria to nitrite and then nitric oxide. Nitrite is a bioactive metabolite of nitric oxide hypothesised to play a role in several metabolic pathways. We explored the effect of nitrate and nitrite in skeletal muscle metabolism and mitochondrial function in mice and humans. Our aims were to assess whether the mouse model is appropriate for use to ascertain the effects of nitrate supplementation, to determine whether these effects are nitrate or nitrite dependent and to investigate whether 7 days nitrate supplementation with nitrate in humans affects metabolism and mitochondrial function. Nitrate supplementation in the mouse, increased plasma nitrate concentration but did not elicit any changes in skeletal muscle metabolism or mitochondrial function at rest. Nitrite supplementation increased plasma nitrate and nitrite concentrations and achieved an increase in metabolic efficiency manifested as a reduction in complex I-linked leak respiration at rest. Nitrate supplementation in humans for 7 days increased plasma nitrate but not nitrite concentration. Skeletal muscle metabolism and mitochondrial function after nitrate did not differ from the placebo. However, blood perfusion of muscles consisting predominantly of type I fibres was increased. Our work suggested that nitrate metabolism is similar between mice and humans and the mouse could be a good model to investigate the effects of nitrate supplementation on skeletal muscle metabolism. This work also suggests that increases in plasma nitrite concentration may be responsible for the changes observed in mitochondrial efficiency. Finally, nitrate supplementation in humans did not elicit any metabolic changes. Deliberate nitrate supplementation in order to increase performance requires further research and any recommendations on increased consumption of nitrates for this purpose may not be accurate.

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20

ARA?JO, Ana Maria Silva de. "Absor??o e metabolismo de nitrog?nio por arroz em diferentes agroecossistemas sob disponibilidade sazonal de N-NO3-." Universidade Federal Rural do Rio de Janeiro, 2011. https://tede.ufrrj.br/jspui/handle/jspui/1260.

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CAPES
CNPq
The wet tropical climate, characteristic of great part of the Northeast, Midwest and part of the Southeast regions of Brazil, present markedly a rainy season and a dry one. During the dry season, the evapotranspiration provides capillary movements of water in soil coincidently with the superficial accumulation of NO3 -. The amount of nitrate in the soil may vary with the seasonality of environmental variables, such as the temperature and precipitation, thus influencing the assimilation process, the consumption and the storage of that ion by the plants. This way, in the beginning of the rainy period there is a great availability of NO3 - in the soil. This phenomenon has being identified as nitrate flush. The objective of the study was to evaluate the possibility of occurrence of synchronism among N-NO3 - flush and absorption of N by two rice varieties dissimilar in the storage capacity and remobilization of N in field conditions. Two experiments were installed in two consecutive years in the town of S?o Luis and in Miranda do Norte, Maranh?o State. The areas had three different management systems: alley cropping, slash-and-burn agriculture (cutting down and burning), and conventional system. The legume trees used were: Leucaena leucocephala (Leucena); Clitoria fairchildiana (Philippine pigeonwings); and Acacia mangium (acacia). They were combined among themselves, in the following treatments: Philippine pigeonwings + Leucena (S + L); Acacia + Leucena (A + L), and a reference plot, without legume trees. The experimental design was of random blocks in sub-subdivided plots with four repetitions. The appraised parameters were: nitrate reductase (NR) activity, the plant N metabolism, the mineralization of N in soil, the seasonal flow of NO3 - in soil, biomass production, and the rice productivity. According to the results, the addition of biomass from legume trees did not cause great alterations in the soil characteristics, in S?o Luis and in the Miranda do Norte areas. In the soil the largest changes were observed for the burnt area and the one with conventional system. The Acacia + Leucena alley cropping influenced significantly most of evaluated variables, and in most of the time they showed superior to Sombreiro + Leucena alley and the testimony. In general, the activity of the nitrate reductase was low, for all systems. However, a variation was verified in the enzyme activity according to sampling period. The results showed the largest reductions in NO3 - in the hems, indicating this is the preferential plant part for N remobilization in rice. The traditional variety always presented lower values of NR activity, and it accumulated more NO3 - compared with the improved variety. There were seasonal variations in the levels of NO3 - and NH4 + in the soil; however the largest accumulations of NH4 + occurred in the superficial layer and in the beginning of the rainy season. The rice productivity was low; however it differed significantly among the management systems.
O clima tropical ?mido, caracter?stico de grande parte do Nordeste, Centro-Oeste e parte do Sudeste do Brasil, apresenta de forma marcante uma esta??o chuvosa e outra seca. Durante a esta??o seca, a evapotranspira??o proporciona movimentos capilares de ?gua no solo coincidentes com o ac?mulo superficial de NO3 -. Esse conte?do de nitrato no solo pode variar com a sazonalidade de vari?veis ambientais, tais como a temperatura e a precipita??o, assim influenciando o processo de assimila??o, o consumo e o armazenamento desse ?on pelas plantas. Portanto, no in?cio do per?odo chuvoso ocorre grande disponibilidade de NO3 - no solo e este fen?meno tem sido denominado como ?flush? de nitrato. O objetivo do estudo foi o de avaliar a possibilidade de ocorr?ncia do sincronismo entre esse ?flush? de N-NO3 - e a absor??o de N por duas variedades de arroz diferentes quanto ? capacidade de armazenamento e remobiliza??o de N em condi??es de campo. Para tal, foram instalados dois experimentos por dois anos consecutivos nos munic?pios de S?o Luis e Miranda do Norte, Estado do Maranh?o em tr?s diferentes sistemas de manejo: cultivo em al?ias, ro?a no toco (derrubada e queima) e sistema convencional. As esp?cies de leguminosas utilizadas foram: Leucaena leucocephala (leucena); a Clitoria fairchildiana (sombreiro) e a Acacia mangium (ac?cia), combinadas entre si, nos seguintes tratamentos: Sombreiro + Leucena (S + L); Ac?cia + Leucena (A+ L) e Testemunha, sem leguminosas. Em todos os sistemas de manejo adotou-se o delineamento experimental de blocos casualizados em parcelas sub-subdivididas com quatro repeti??es. Os par?metros avaliados foram ? atividade da nitrato redutase, o metabolismo do N na planta, o fluxo sazonal de NO3 - no solo, produ??o de biomassa e a produtividade do arroz. De acordo com resultados, a adi??o de biomassa das leguminosas n?o causou grandes altera??es nas caracter?sticas do solo tanto em S?o Luis quanto no munic?pio de Miranda do Norte. No solo as maiores altera??es foram observadas para o a ?rea queimada e a ?rea mantida em sistema convencional. As al?ias de Ac?cia + Leucena influenciaram de forma significativa a maioria das vari?veis avaliadas apresentando-se na maioria das vezes superiores as al?ias de Sombreiro + Leucena e a testemunha. No geral, a atividade da nitrato redutase foi baixa em todos os sistemas de manejo. No entanto, constatou-se varia??o na atividade da enzima em fun??o ?poca de amostragem. Os resultados mostraram que as maiores redu??es nos teores de NO3 - foram observados nas bainhas, indicando ser este o local preferencial para a remobiliza??o de N em arroz. A variedade tradicional apresentou sempre valores mais baixos de atividade da NR e acumulou mais NO3 - comparada com a variedade melhorada. Houve varia??es sazonais no teor de NO3 - e NH4 + no solo, por?m os maiores ac?mulos de NH4 + ocorreram na camada superficial e in?cio da esta??o chuvosa. A produtividade do arroz foi baixa, por?m diferiu de forma significativa entre os sistemas de manejo.

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21

Wang, Kehua. "Effects of Nitrate and Cytokinin on Nitrogen Metabolism and Heat Stress Tolerance of Creeping Bentgrass." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/39049.

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Creeping bentgrass (Agrostis stolonifera L.) is a major low-cut cool-season turfgrass used worldwide. The objectives of this research were to: 1) to gain insight into the diurnal fluctuation of N metabolism and effects of cytokinin (CK) and nitrate; 2) to characterize the impacts of N and CK on creeping bentgrass under heat stress; 3) to investigate the simultaneous effects of CK and N on the antioxidant responses of heat stressed creeping bentgrass; and 4) to examine the expression pattern of the major heat shock proteins (HSPs) in creeping bentgrass during different heat stress periods, and then to study the influence of N on the expression pattern of HSPs. The transcript abundance of nitrate reductase (NR), nitrite reductase (NIR), plastidic glutamine synthetase (GS2), ferredoxin-dependent glutamate synthase (Fd-GOGAT), and glutamate dehydrogenase (GDH) and N metabolites in shoots were monitored during the day/night cycle (14/8 h). All the measured parameters exhibited clear diurnal changes, except GS2 expression and total protein. Both NR expression and nitrate content in shoots showed a peak after 8.5 h in dark, indicating a coordinated oscillation. Nitrate nutrition increased diurnal variation of nitrate content compared to control and CKHowever, CK shifted the diurnal in vivo NR activity pattern during this period. Grass grown at high N had better turf quality (TQ), higher Fv/Fm, normalized difference vegetation index (NDVI), and chlorophyll concentration at both 15 d and 28 d of heat stress than at low N, except for TQ at 15 d. Shoot NO3-, NH4+, and amino acids increased due to the high N treatment, but not water soluble proteins. High N also induced maximum shoot nitrate reductase activity (NRmax) at 1 d. CK increased NDVI at 15 d and Fv/Fm at 28 d. In addition, grass under 100 ÂµM CK had greatest NRmax at both 1 d and 28 d. Under high N with 100 ÂµM CK, root tZR and iPA were 160% and 97% higher than under low N without CK, respectively. Higher O2- production, H2O2 concentration, and higher malonydialdehyde (MDA) content in roots were observed in grass grown at high N. The activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and guaiacol peroxidase (POD) in roots were enhanced by high N at 19, 22, and 24% levels, respectively, relative to low N. Twenty-eight days of heat stress resulted in either the development of new isoforms or enhanced isoform intensities of SOD, APX, and POD in roots compared to the grass responses prior to heat stress. However, no apparent differences were observed among treatments. No CK effects on these antioxidant parameters were found in this experiment. At week seven, grass at medium N had better TQ, NDVI, and Fv/Fm accompanied by lower shoot electrolyte leakage (ShEL) and higher root viability (RV), suggesting better heat resistance. All the investigated HSPs (HSP101, HSP90, HSP70, and sHSPs) were up-regulated by heat stress. Their expression patterns indicated cooperation between different HSPs and that their roles in creeping bentgrass thermotolerance were affected by N level.
Ph. D.

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22

Boadas, Vaello Pere. "Neurotoxicitat i metabolisme de nitrils a la rata i el ratolí." Doctoral thesis, Universitat de Barcelona, 2008. http://hdl.handle.net/10803/1155.

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Els nitrils són compostos químics que contenen el grup ciano: C N. Són molt abundants en la naturalesa, però la seva síntesi és també molt important pel gran ventall d'aplicacions que aquests aporten a la indústria. A la naturalesa els trobem, entre d'altres, en forma de glucòsids cianogènics com és el cas de l'amigdalina a les ametlles amargants i la linamarina a la mandioca, i en forma d'aminonitrils, forma que es troba a les lleguminoses del gènere Lathyrus. A la indústria s'utilitzen com a dissolvents i productes intermediaris en la síntesi de plàstics, fibres artificials, resines, productes farmacèutics i altres substàncies químiques. El consum humà o animal de determinats nitrils provoca símptomes similars a la intoxicació per cianur. Aquest fet suggereix que en la metabolització d'aquests nitrils es produeix l'alliberament d'aquest compost i que seria el responsable de la intoxicació aguda. Alguns nitrils però, en aquest procés de metabolització alliberen menys cianur o n'alliberen més lentament i aquests són els que provoquen neurotoxicitat i síndromes neurològiques. L'estudi d'aquest tipus de nitrils adquireix importància com a models de neurotoxicitat i de síndromes de toxicitat humanes causades per nitrils d'origen natural.
A la primera part d'aquest treball de tesi s'ha pogut caracteritzar exhaustivament les dianes del 3,3'-iminodipropionitril (IDPN), l'al·lilnitril, el cis-crotononitril, el trans-crotononitril i el 2,4-hexadienenitril al sistema nerviós de la rata i establir la relació entre les lesions estructurals i els efectes comportamentals que aquests provoquen. Per a aquesta caracterització global, s'ha treballat amb un disseny experimental que combina experiments histopatològics amb tests d'avaluació comportamental animal. Els resultats han permès dividir els nitrils neurotòxics en dos grups, els que afecten al sistema nerviós central (trans-crotononitril i hexadienenitril) i els que afecten els sistemes sensorials (IDPN, al·lilnitril i cis-crotononitril).
A la segona part de la tesi es demostra que la toxicitat vestibular de nitrils no és un fenomen exclusiu de la rata, sinó que ocorre també en altres espècies incloent-hi mamífers i no mamífers. Aquest resultats obren la porta a l'ús de soques de ratolins transgènics en l'estudi d'aquesta toxicitat.
A la tercera part de la tesi s'estudia el paper de la metabolització d'aquests nitrils per a provocar els efectes neurotòxics. Concretament s'ha avaluat la bioactivació de la toxicitat vestibular del cis-crotononitril i l'al·lilnitril mitjançant el citocrom P450 2E1 utilitzant ratolins 129S1, ratolins transgènics pel citocrom P4502E1 i inhibidors selectius (Dial·lilsulfur) i no selectius (Aminobenzatriazol) d'aquest citocrom. A més, en aquesta segona part s'explica el procés d'optimització d'una metodologia que permet detectar simultàniament cianur i nitrils volàtils en sang, que combina la tècnica SPME (microextracció en fase sòlida) i la cromatografia de gasos amb detector NPD (detector nitrogen-fòsfor). Amb aquests treballs es demostra que tant l'al·lilnitril com el cis-crotononitril són substrats del citocrom P450 2E1 però que mitjançant aquest citocrom s'activa una via cianogènica no necessàriament vestibular. Els resultats obtinguts ens han permès concloure que la toxicitat vestibular d'aquets nitrils depèn d'un citocrom P450 diferent al 2E1 i que la via metabòlica amb efectes vestibulars més probable per a l'al·lilnitril és la de l'epoxidació del doble enllaç en posició beta-gamma.
SUMMARY:

Nitriles are increasingly used in the chemical industry, and they are also common in crop plants. They cause acute lethality, osteolathyrism and neurotoxicity.
In the first part of this thesis, we compared the behavioural effects of IDPN, allylnitrile, cis-crotononitrile, trans-crotononitrile, and hexadienenitrile in the rat using test methods sensitive to the ECC (Excitation with Choreiform and Circling movements) syndrome or to the trans-crotononitrile syndrome. In addition, we assessed the CNS effects of these nitriles with the Fluoro-Jade B stain, which selectively labels degenerating neurons. In conclusion, the present and previous data indicate that neurotoxic nitriles induce one of two syndromes of abnormal motor behaviour: (1) the ECC syndrome caused by IDPN, allylnitrile, and cis-crotononitrile, and resulting from degeneration of the vestibular sensory hair cells with no CNS toxicity role, and (2) the syndrome of faltering movements, caused by trans-crotononitrile and hexadienenitrile, and resulting from degeneration of the inferior olive neurons.
In the second part of this thesis, we demonstrate that nitriles that are toxic to the vestibular and auditory systems of the rat are also ototoxic to other animal species, both mammals and no mammals. The findings open up the possibility of using species other than the rat to study this toxic effect of nitriles and the possibility of using nitriles for inner ear research performed in diverse animal species.
In the third part of this thesis, we assessed the hypotheses that the vestibular or lethal toxicities of cis-crotononitrile and allylnitrile depend on CYP2E1-mediated bioactivation. Wild-type (129S1) and CYP2E1-null mice were exposed to cis-crotononitrile and allylnitrile in either a baseline condition or following exposure to 1% acetone in drinking water to induce CYP2E1 expression. In parallel groups, concentrations of cis-crotononitrile, allylnitrile and cyanide were assessed in whole blood using an optimized SPME GC-NPD methodology. Also further groups of animals were used to test the effect the non selective P450 inhibitor 1-aminobenzotriazole and the CYP2E1-selective inhibitor diallylsulfide on the toxicity of allylnitrile. We conclude that allylnitrile and cis-crotononitrile are CYP2E1 substrates and that CYP2E1-mediated metabolism of these nitriles leads to cyanide release and acute mortality, while a different P450 system bioactivates these nitriles for vestibular toxicity. We propose that CYP2E1 acts on allylnitrile by alfa-carbon hydroxylation and that an action on the beta-gamma-double bound is more likely responsible for the vestibular effect.
Los nitrilos son compuestos químicos que contienen el grupo ciano: -CN. Son muy abundantes en la naturaleza, pero su síntesis es también muy importante por el amplio rango de aplicaciones que estos aportan a la industria. En la naturaleza los encontramos en forma de glucósidos cianogénicos, como la amigdalina de las almendras amargas y la linamarina de la yuca, y en forma de aminonitrilos, forma que se encuentra en las leguminosas del género Lathyrus. En la industria se utilizan como disolventes i productos intermediarios en la síntesis de plásticos, fibras artificiales, resinas, productos farmacéuticos i otras sustancias químicas. El consumo humano o animal de determinados nitrilos provoca síntomas similares a la intoxicación por cianuro. Este hecho sugiere que en la metabolización de estos nitrilos se produce la liberación de este compuesto y que sería el responsable de la intoxicación aguda. Algunos nitrilos, en este proceso de metabolización, liberan menos cianuro o lo hacen de forma más lenta y estos son los que provocan neurotoxicidad y síndromes neurológicos. El estudio de estos nitrilos adquiere importancia como modelos de neurotoxicidad y síndromes neurológicos de toxicidad humana causados por nitrilos de origen natural.
En la primera parte de este trabajo de tesis se ha podido caracterizar de forma exhaustiva las dianas del 3,3'-iminodipropionitrilo (IDPN), el alilnitrilo, el cis-crotononitrilo, el trans-crotononitrilo i el 2,4-hexadienenitrilo en el sistema nervioso central y establecer la relación entre las lesiones estructurales y los efectos comportamentales que estos provocan. Para esta caracterización global, se ha trabajado con un diseño experimental que combina experimentos hitopatológicos con tests de evaluación comportamental animal. Los resultados han permitido dividir los nitrilos neurotóxicos en dos grupos, los que afectan al sistema nervioso central (trans-crotononitrilo y hexadienenitrilo) y los que afectan a los sistemas sensoriales (IDPN, alilnitrilo y cis-crotononitrilo).
En la segunda parte de la tesis se demuestra que la toxicidad vestibular de nitrilos no es un fenómeno exclusivo de la rata, sino que ocurre también en otras especies incluyendo mamíferos y no mamíferos. Estos resultados abren las puertas a la utilización de ratones transgénicos en el estudios de dicha toxicidad.
En la tercera parte de la tesis se estudia el papel de la metabolización de estos nitrilos para provocar los efectos neurotóxicos. Concretamente se ha evaluado la bioactivación de la toxicidad vestibular del cis-crotononitrilo y el alilnitrilo mediante el citocromo P450 2E1 utilizando ratones 129S1, ratones transgénicos para el citocromo P450 2E1 y inhibidores selectivos (dialilsulfuro) y no selectivos (aminobenzatriazol) de este citocromo. Además, en esta tercera parte se explica el proceso de optimización de una metodología que permite detectar simultáneamente cianuro y nitrilos volátiles en sangre, que combina la técnica SPME (microextracción en fase sólida) y la cromatografía de gases con detector NPD (detector nitrógeno-fósforo). Con estos trabajos se demuestra que tanto el alilnitrilo como el cis-crotononitrilo son sustratos del citocromo P450 2E1 pero que mediante este citocromo se activa una vía cianogénica no necesariamente vestibular. Los resultados obtenidos nos han permitido concluir que la toxicidad vestibular de estos nitrilos depende de un citocromo P450 diferente al 2E1 y que la vía metabólica con efectos vestibulares más probable para el alilnitrilo es la epoxidación del doble enlace en posición beta-gamma.

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Borella, Junior. "Adaptações metabólicas de genótipos de soja em resposta à deficiência de oxigênio e envolvimento do nitrato." Universidade Federal de Pelotas, 2015. http://repositorio.ufpel.edu.br:8080/handle/prefix/3589.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
O alagamento é um fator ambiental comum que causa deficiência de oxigênio às plantas, levando a uma inibição da respiração e redução do status energético celular, desencadeando uma série de mudanças no metabolismo do carbono e do nitrogênio. Além disso, alterações no fluxo de elétrons da cadeia de transporte de elétrons mitocondrial e cloroplastídica levam a produção de espécies reativas de oxigênio (EROs) que podem ocasionar vários danos ao metabolismo celular. No entanto, a aplicação exógena de nitrato tem sido reportada por promover efeitos benéficos em muitas espécies de plantas sob condições de hipóxia. Embora muitos estudos tenham sido envidados com soja, pouco se sabe a respeito das alterações metabólicas primárias do carbono e do nitrogênio que permitem diferenciar genótipos contrastantes ao alagamento e os efeitos no sistema antioxidante pela aplicação exógena de nitrato nas plantas. Considerando o exposto, os objetivos deste trabalho foram: I – avaliar mudanças no metabolismo do carbono e do nitrogênio e sua relação com a enzima alanina aminotransferase (AlaAT) em genótipos de soja nodulada; II – verificar possíveis efeitos benéficos no metabolismo antioxidante em plantas cultivadas na presença de nitrato (plantas não-noduladas) e na ausência de nitrato (plantas noduladas). Para isso, dois experimentos foram conduzidos em casa de vegetação com plantas de soja (Glycine max (L.) Merril) sob condições naturais de luz e temperatura. Experimento I: plantas noduladas de soja, nutridas na ausência de N mineral (Fundacep 53 RR – tolerante e BRS Macota – sensível) foram cultivadas em vermiculita e transferidas para sistema hidropônico, no estádio reprodutivo R2. O sistema radicular das plantas foi submetido à hipóxia pelo borbulhamento de nitrogênio gasoso na solução nutritiva diluída 1/3 da concentração normal, por 24 e 72 h. Para recuperação, após 72 h de hipóxia as plantas retornaram para vermiculita por 24 e 72 h. Foram avaliados, em raízes e nódulos, metabólitos fermentativos e ácidos orgânicos (GC-MS), aminoácidos (HPLC), expressão relativa dos genes (RT-PCR) e atividade da enzima AlaAT. Fundacep 53 RR acumulou mais teores de piruvato e lactato que BRS Macota e embora a composição de aminoácidos não tenha diferido entre os genótipos, foi observado uma ligação entre a glicólise e o ciclo dos ácidos tricarboxílicos via indução dos genes e atividade da AlaAT, que, posteriormente, levou ao acúmulo de succinato em raízes de Fundacep 53 RR, podendo aumentar o ganho energético em relação à BRS Macota sob hipóxia. Experimento II: A condução experimental adotada foi semelhante ao experimento I, no entanto conduzido com plantas noduladas e não-noduladas (nutridas com nitrato) de soja, de ambos os genótipos. Foi avaliado o sistema antioxidante em raízes e folhas através da atividade das enzimas superóxido dismutase (SOD), ascorbato peroxidase (APX), catalase (CAT), glutationa redutase (GR), guaiacol peroxidase (GPOD) e glutationa S-transferase (GST), o conteúdo de ascorbato reduzido e ascorbato total, bem como conteúdo de superóxido (O2), peróxido de hidrogênio (H2O2) e peroxidação de lipídeos. O sistema antioxidante foi fortemente induzido nas raízes das plantas nutridas com nitrato de ambos os genótipos, com elevada atividade de SOD, APX, CAT, GR e GPOD, bem como o aumento do conteúdo de ascorbado reduzido e total e diminuição da produção de EROs em condições de hipóxia e de recuperação, enquanto que nas folhas de plantas noduladas e não-noduladas foi observado um ligeiro aumento nos componentes enzimáticos e não enzimáticos antioxidantes. O nitrato exerce efeitos benéficos em plantas de soja em condições de hipóxia e consequentemente na recuperação por induzir o sistema antioxidante nas raízes, permitindo modular os possíveis danos oxidativos causados pela produção de EROs, além de poder prolongar a tolerância dessas plantas.
Waterlogging is a common environmental stress which causes oxygen deprivation in plants leading to an inhibition of the mitochondrial respiration. It leads to a reduction of cellular energy status triggering changes at different levels of carbon and nitrogen metabolism. In addition, it leads to electron scape from the mitochondrial and chloroplast electron transport chain, producing reactive oxygen species (ROS) which cause severe oxidative damage to cells. However, exogenous nitrate supply has been reported to promoting beneficial effects in several plant species under hypoxic conditions. Although many studies have been carried out with soybean, a little is known about the primary metabolic changes in carbon and nitrogen metabolism, which may differ between tolerant and sensitive plant genotypes in response to waterlogging and the effects on antioxidant system in nitrate-supplied plants in comparison to non-nitrate-supplied plants. Thus, the aims of this study were: I – to evaluate the hypoxia-induced alterations of carbon and nitrogen metabolism and its relation with alanine aminotransferase (AlaAT) enzyme in nodulated soybean genotypes; II – to verify possible beneficial effects on antioxidant metabolism in nitrate-supplied plants (non-nodulated plants) in comparison to plants growing in absence of nitrate (nodulated plants). For that, two experiments were carried out in greenhouse under natural light and temperature conditions. Experiment I: Nodulated soybean plants (Fundacep 53 RR – tolerant and BRS Macota – sensitive) were grown in vermiculite and transferred to hydroponic system at reproductive stage. Root system was subjected to hypoxia by flushing N2 gas into the solution for 24 or 72 h. For the recovery, after 72 h in hypoxia, plants returned to normoxic conditions by transferring back to vermiculite for 24 and 72 h. Root and nodule organic acids and amino acids were analysed by gas chromatography-mass spectrometry and high-performance liquid chromatography, respectively. Relative expression of AlaAT (qRT-PCR) and AlaAT activity were also verified in both genotypes. Plants of Fundacep 53 RR and BRS Macota genotypes responded distinctly upon hypoxia. Fundacep 53 RR presented higher pyruvate and lactate accumulation than BRS Macota, which is indicative of higher glycolytic and fermentation rates in root tissues. Furthermore, Fundacep 53 RR responds more effectively to the recovery by restoring pre-hypoxic levels of the metabolites. Although the amino acid composition did not differ between the genotypes, there was a clear link between glycolysis and the TCA via increase of gene expression and activity of AlaAT enzyme by leading a succinate accumulation in Fundacep 53 RR, wich represents a metabolic advantage compared to BRS Macota under hypoxic stress. Experiment II: was carried out in a similar way of Experiment I, however with plants growing in presence (non-nodulated) and absence (nodulated) of nitrate, for both soybean genotypes. Superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), guayacol peroxidase (GPOD) and glutathione S-transferase (GST) enzymes; reduced ascorbate and ascorbate redox state; superoxide content (O2•-), hydrogen peroxide (H2O2) and lipid peroxidation were analysed in roots and leaves of both soybean genotypes. Antioxidative system was strongly induced in roots of nitrate-supplied plants of both genotypes, with high activity of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR) and guayacol peroxidase (GPOD), as well as increased ascorbate reduced and ascorbate redox state and decreased ROS production under hypoxia and recovery, while in leaves of nodulated and non-nodulated plants a slight increase on antioxidant system was observed. Furthermore, the results did not show tolerance differences between the genotypes. Nitrate exerts beneficial effects in soybean plants under hypoxic conditions and consequent recovery by inducing the antioxidant system manly in roots, to cope possible oxidative damage caused by ROS production and also can postpone the effects of hypoxia in both genotypes.

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24

Laginha, Alberto Manasse [Verfasser]. "Contribution of ammonium transporters to growth, nitrate uptake, metabolism and development in Arabidopsis thaliana / Alberto Manasse Laginha." Halle, 2019. http://d-nb.info/1177034085/34.

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25

Goda, Masahiko. "Basic and applied studies of the enzymes involved in the microbial metabolism of nitrile and isonitrile compounds." Kyoto University, 2002. http://hdl.handle.net/2433/149888.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第9596号
農博第1224号
新制||農||840(附属図書館)
学位論文||H14||N3628(農学部図書室)
UT51-2002-G354
京都大学大学院農学研究科応用生命科学専攻
(主査)教授清水昌, 教授加藤暢夫, 教授江﨑信芳
学位規則第4条第1項該当

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26

MacKenzie, Douglas Allan. "Strain-Promoted Alkyne-Nitrone Cycloadditions: Developing Bioorthogonal Labelling Strategies." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32733.

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Chemical transformations that join two molecular components together rapidly while remaining highly efficient and selective are valued for their elegant simplicity and effectiveness in a myriad of applications. By applying the principles of ‘click’ chemistry to biology, information about molecular interactions in vivo can therefore be gained from minimally perturbing bioorthogonal coupling reactions. Developing bioorthogonal ‘click’ reactions – reactions that do not cross-react with biological components – provides new ways to accurately study biological systems at the molecular level. This thesis describes the development of such tools. Strain-promoted alkyne-nitrone cycloadditions (SPANC) represent rapid, efficient, selective, and tunable conjugation strategies that are applicable to biomolecular labelling experiments. Herein, SPANC reactions with bicyclo[6.1.0]nonyne are examined using physical organic methods to determine the stereoelectronic factors governing SPANC reactivity. Second-order rate constants (k2) of up to 1.49 M-1s-1 were measured and the resulting cycloadditions are applied to the design and synthesis of nitrone-based molecular probes. The first example of SPANC-mediated metabolic labelling in live-cell bacteria is reported, establishing SPANC as an efficient and bioorthogonal metabolic labelling strategy for cellular labelling.

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Cruz, Jailson Lopes. "Efeitos de níveis do nitrato sobre o metabolismo do nitrogênio, assimilação do CO 2 e fluorescência da clorofila a em mandioca." Universidade Federal de Viçosa, 2001. http://www.locus.ufv.br/handle/123456789/11003.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Plantas de mandioca (Manihot esculenta Crantz ‘Cigana Preta’) foram cultivadas com diferentes concentrações de NO -3 , para avaliar-se possíveis alterações no metabolismo do nitrogênio, assimilação do CO 2 e parâmetros de fluorescência da clorofila a. Os experimentos foram conduzidos em solução nutritiva, em blocos ao acaso. Após 90 dias de cultivo, verificou-se que os níveis de nitrogênio foliar total e de suas frações (NO -3 , NH +4 , aminoácidos e proteínas solúveis), bem como as atividades das enzimas redutase do nitrato, desidrogenase do glutamato, sintetase da glutamina e sintase do glutamato foram reduzidas pela menor disponibilidade de NO -3 no meio de cultivo. Nas folhas, os teores de açúcares solúveis totais, de açúcares não-redutores e de fósforo inorgânico, aumentaram linearmente, com o incremento dos níveis NO -3 , mas os níveis de amido e açúcares redutores diminuíram. Nas raízes de absorção e raízes tuberosas, os níveis de amido e açúcares redutores também foram maiores para as plantas cultivadas sob deficiência de NO -3 . A deficiência de NO -3 ocasionou reduções nas taxas fotorrespiratória e fotossintética líquida e, paralelamente, proporcionou aumento na taxa respiratória total. A manutenção dos valores de C i /C a , F v /F m , F v ́/F m ́e aumento nos níveis de redução de Q A , verificados nas plantas cultivadas sob deficiência de NO -3 , indicaram que a menor taxa fotossintética líquida, por unidades de área e de massa, não foi devida a limitações estomáticas e tampouco ao funcionamento da etapa fotoquímica, mas em função: (i) da menor concentração de proteínas, presumivelmente aquelas relacionadas com a etapa bioquímica da fotossíntese, (ii) da menor taxa de carboxilação da Rubisco, (iii) da menor disponibilidade de Pi e, (iv) da retroinibição devida ao acúmulo de açúcares redutores.
Cassava plants (Manihot esculenta Crantz 'Cigana Preta') were grown with nitrate in different levels (0.5; 3.0, 6.0 and 12.0 mol m -3 NO -3 ) to evaluate possible alterations in nitrogen metabolism, CO 2 assimilation and chlorophyll a fluorescence parameters. Experiments were conducted in nutrients solution, in a randomized block design. After 90 days of cultivation, total leaf nitrogen concentration and its fractions (NO -3 , NH +4 , aminoacids and soluble proteins), as well as the activies of nitrate reductase, glutamate dehydrogenase, glutamine synthetase and glutamate synthase were decreased in the plants under lowest nitrate level treatments. In leaves, concentration of total soluble sugars, non- reducing sugars and inorganic phosphate increased linearlly along with nitrate levels, whilst starch and reducing sugars decreased. In both absorbing and tuberous roots, concentration of starch and reducing sugars were higher in plants grown under nitrate deficiency. Such a deficiency also led to reductions in photorespiratory rates and net CO 2 assimilation, but an opposite trend in total respiration rate was found. Maintenance of (i) internal to ambient CO 2 ratio, (ii) both dark and light-adapted variable to maximum chlorophyll fluoresecence ratio and (iii) an increase in the reduction state of Q A under nitrate deficiency suggested that decreased net CO 2 assimilation, on both area and mass bases, was a consequence of biochemical limitations, due possibly to (i) a decreased concentration of proteins, presumably the ones associated with the Calvin cycle, (ii) a decreased rate of Rubisco carboxylation, (iii) a decline in Pi availability and, (iv) an end-product inibition owing to the reducing sugars accumulation.
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28

Schmitt, Romain. "S-nitrosoglutathion et perméabilité intestinale : de la mise en place d’un modèle de chambre de Ussing à l’étude de l’impact de ce donneur de monoxyde d’azote sur la barrière intestinale Involved factors in the maintenance of intestinal barrier homeostasis: a review How to guarantee results from ex vivo studies based on Ussing chamber system for studying intestinal barrier integrity and function Comparison between two derivatization methods of nitrite ion labeled with 15N applied to liquid chromatography-tandem mass spectrometry Influence of S-nitrosoglutathione metabolism on its intestinal permeability Luminal S-nitrosoglutathione effects on intestinal barrier in an ex vivo model of Ussing chamber." Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0342.

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Le monoxyde d’azote (NO) est connu pour ses nombreuses actions afin de maintenir l’homéostasie de la barrière intestinale, régulant la sécrétion de mucus, le stress oxydant, le système immunitaire… Le S-nitrosoglutathion (GSNO), donneur de NO naturellement produit par l’organisme, a montré une action bénéfique sur le renforcement de la barrière intestinale. L’enjeu est aujourd’hui de comprendre les mécanismes inhérents à cette observation. Pour ce faire une étude en Chambre de Ussing a été menée. Une fois le modèle d’étude validé par le suivi de marqueurs de perméabilité, les études histologiques et d’expression des protéines de jonctions cellulaires, le métabolisme du GSNO administré dans la lumière de l’intestin ont été explorés. Également, l’effet du GSNO sur la perméabilité de la barrière intestinale a été étudié. Les résultats permettent aujourd’hui d’envisager le GSNO comme une piste thérapeutique intéressante et prometteuse aux multiples applications possibles : intestinales, cardiovasculaires ou encore cérébrales
Nitric oxide is known for its many actions to maintain intestinal barrier homeostasis, regulating mucus secretion, oxidative stress, immune system… S-nitrosoglutathione (GSNO), a nitric oxide donor naturally produced by the organism, has shown a beneficial effect on the intestinal barrier reinforcement. Nowadays, challenge is to understand the mechanisms inherent to this observation. For that, a Ussing chamber study was performed. After the model validation, by following permeability markers, histological studies, and cell junction proteins expression study, the GSNO metabolism administered in the intestinal lumen was explored. Also, GSNO effect on the intestinal barrier permeability was evaluated. Results allow today to consider GSNO as an interesting and promising drug candidate, in the context of intestinal, cardiovascular or cerebral pathologies

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29

Viršilė, Akvilė. "Fotofiziologiniai efektai metabolitų dinamikai žalumyninėse daržovėse ir želmenyse." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20120620_142825-38345.

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Tyrimų tikslas. Ištirti kietakūnio apšvietimo, pagrįsto šviesą emituojančių diodų technologija, panaudojimo galimybes žalumyninių daržovių, želmenų ir daigintų sėklų vidinės kokybės rodikliams valdyti. Mokslinis naujumas. Pirmą kartą nustatyta, kad raudona 638 nm šviesa ir jos derinys su raudona 669 nm, mėlyna 447 nm ir tolimąja raudona 731 nm šviesa paskatina nitratų redukcijos procesus salotose ir kitose žalumyninėse daržovėse. Nustatyta, kad reikšmingam teigiamam efektui žalumyninių daržovių vidinei kokybei pasiekti pakanka jas švitinti didelio tankio fotosintetiškai aktyvios raudonos 638 nm spinduliuotės srautu ~72 h prieš planuojamą derliaus nuėmimą. Pirmą kartą įvertintas kietakūnio apšvietimo spektro efektas skirtingų lietuviškų javų želmenų, lapinių ridikėlių ir daigintų sėklų antioksidacinėms savybėms. Nustatytas teigiamas raudonų 638, 669 nm, mėlynos 447 nm ir tolimosios raudonos 731 nm bangų ilgių deriniui papildomų žalios 518 nm ir geltonos 595 nm šviesos efektas natūraliai aukštomis bioaktyvių medžiagų koncentracijomis audiniuose išsiskiriančių žalumyninių daržovių ir želmenų antioksidacinėms savybėms. Darbo praktinė svarba. Įvertintos originalios konstrukcijos kietakūnio apšvietimo įrenginių taikymo žalumyninių daržovių vidinei kokybei gerinti galimybės. Remiantis darbe nustatytais dėsningumais, parengtas ir patentuotas žalingų nitratų kiekio augaluose sumažinimo, apšvitinant kietakūnio šviestuvo sukuriamu šviesos srautu, metodas ir įrenginys. Atliktų tyrimų... [toliau žr. visą tekstą]
The aim of the research was to investigate the usability of the solid state lighting, based on light emitting diode technology, for the management of nutritional quality indices in green vegetables and sprouts. Scientific originality. It was determined for the first time, that red 638 nm light and its combination with blue 447 nm, red 669 nm and far red 731 nm light promoted nitrate reduction processes in lettuce and other green vegetables. It is enough to irradiate green vegetables with the high flux of photosyntheticaly active 638 nm red light for ~72 h before harvesting for the pronounced positive effect on their internal quality. The effect of the solid-state lighting spectra on antioxidant properties of Lithuanian cereal greens, leafy radish and sprouted seeds was evaluated for the first time. The positive effect of green 518 nm and yellow 595 nm light, supplemental for the red 638, 669 nm light, blue 447 nm and far red 731 nm light on the antioxidant properties of green vegetables and sprouts, naturally containing higher concentrations of bioactive compounds, was determined. Practical value of the work. Solid-state lighting application possibilities for the improvement of green vegetable internal quality were evaluated. According to defined trends, the method and apparatus for the reduction of harmful nitrates in plants, when irradiating plants with the light flux generated by semiconductor lighting unit, was designed and patented. The complex investigations and... [to full text]

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30

Goutouly, Jean-Pascal. "Régulation de l'absorption de NO3- chez le pêcher : étude en solution nutritive." Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL066N.

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Les conséquences d'une disponibilité nitrique hétérogène sur l'absorption de NO3-, sont étudiées chez des pêchers (Prunus persica (L. ) Batsch), greffés sur prunus Damas 1869, âgés de 3 à 5 ans. Chaque système racinaire a été biparti et placé dans deux conteneurs de solution nutritive de concentration en NO3- variable. L’analyse a plus particulièrement portée sur les mécanismes impliqués dans la régulation de l'absorption de NO3-. L’absorption de NO3- varie largement au cours du nycthémère, l'absorption nocturne représentant environ 30 à 45% de l'absorption totale de NO3-. Lors de la limitation partielle ou totale de la disponibilité de NO3- dans une partie du système racinaire, la vitesse d'absorption de NO3- de l'autre partie, maintenue bien alimentée, augmente. Un résultat inverse est obtenu lors d'un fort apport localisé de NO3-. La diminution ou la suppression de l'arrivée aux racines d'assimilats issus de la photosynthèse, par un ombrage ou une décortication annulaire, entraine un arrêt rapide de l'absorption de NO3-. Une levée de l'ombrage ou un apport de glucose dans la solution nutritive, permet la reprise de l'absorption de NO3-. Une étude de transferts hydriques, avec les isotopes stables de l'eau (oxygène 18 et deutérium), a mis en évidence des trajets préférentiels d'eau entre les zones racinaires et des zones du feuillage. L’étude du transfert des produits de l'assimilation racinaire de 15 NO3- montre que cette distribution s'effectue selon les trajets empruntés par l'eau. Reprenant l'ensemble de ces observations, un schéma général de fonctionnement est proposé, en terme de relations carbone-azote à l'échelle de l'arbre entier

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31

Li, Youzhong, and Youzhong Li@health gov au. "Respiration and nitrogen fixation by bacteroids from soybean root nodules : substrate transport and metabolism in relation to intracellular conditions." The Australian National University. Faculty of Science, 2003. http://thesis.anu.edu.au./public/adt-ANU20040630.114138.

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Bacteroids of B. japonicum from nodules of soybean roots were isolated using differential centrifugation (the standard bench method) and density gradient centrifugation methods (either sucrose- or Percoll-) under anaerobic conditions in which N2 fixation was preserved. The relationships between N2 fixation and respiration, O2 supply, O2 demand, substrate (mainly malate) transport and metabolism in bacteroids were investigated using the flow chamber system. In related experiments, the primary products of N2 fixation which leave the bacteroids were investigated using a 15N-labelling technique in a closed shaken system and other biochemical methods.¶ In the flow chamber experiments, the rates at which O2 was supplied to bacteroids in the chamber were varied by (a) changing the flow rate of reaction medium through the chamber; (b) by changing the [O2 free] in the inflowing reaction medium by using either 3-5% (v/v) or 100% air in the gas mixture above the stirred reaction medium in two reservoir flasks; (c) by successively withdrawing bacteroids from the chamber, thus increasing the supply of O2 per bacteroid to those remaining in the chamber. The results showed that the rate of O2 supply regulates respiratory demand for O2 by bacteroids rather than the O2 concentration present in the reaction system. Respiration is always coupled to N2 fixation. ¶ Uptake of malate by bacteroids withdrawn from the flow chamber was measured under microaerobic conditions. Malate uptake by these N2-fixing bacteroids was lower than that by bacteroids isolated under aerobic conditions, which eliminate N2 fixation of bacteroids, but is closely correlated with bacteroid respiration rates. When respiration was increased by an increase in O2 supply, malate uptake by bacteroids was also increased. This suggested that transport of malate through the bacteroid membrane is also regulated by O2 supply, but indirectly. Higher uptake by bacteroids under aerobic conditions was observed because respiration was enhanced by the high availability of O2, but the fast uptake of malate by bacteroids driven by the abnormal respiration rates may not reflect the reality of malate demand in vivo by bacteroids when N2 fixation by bacteroids is fully coupled. ¶ The results of 15N labelling experiments and other biochemical assays once again demonstrated that ammonia is the principal significant 15N labelled product of N2 fixation accumulated during 30 min in shaken assays with 0.008-0.01 atm O2. Alanine although sometimes found in low concentrations in the flow chamber reactions, was not labelled with 15N in shaken closed system experiments. No evidence could be obtained from the other biochemical assays, either. Therefore, it is concluded that these and earlier results were not due to contamination with host cytosolic enzymes as suggested by Waters et al. (Proc. Natl. Aca. Sci. 95, 1998, pp 12038-12042). ¶ Malate transported into bacteroids is oxidized in a modified TCA cycle present in bacteroids. The results of flow chamber experiments with a sucA mutant (lacking a-ketoglutarate dehydrogenase) showed that respiratory demand for O2 by the mutant bacteroids is regulated by O2 supply in the same way as the wild-type. Despite differences in other symbiotic properties, rates of nitrogen fixation by the mutant bacteroids, based on the bacteroid dry weight, appeared to be the same as in the wild-type. Also N2 fixation was closely coupled with respiration in the same manner in both mutant bacteroids and wild type bacteroids. These results and other supporting data, strongly support the conclusion that there is an alternative pathway of the TCA cycle in bacteroids, which enables the missing step in the mutant to be by-passed with sufficient activity to support metabolism of transported malate.

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32

Barbieri, Francesca. "Effects of the inclusion of microalgae spirulina (Spirulina platensis) in the diet of Gilthead Sea bream (Sparus aurata) on growth and metabolism." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13402/.

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In gilthead seabream aquaculture, the feed supplies in the market is very expensive due to its high content of animal protein. In this respect, spiruline appears to be a valuable substitute to animal and vegetable protein. In this study we performed two experiments. The scope of the first one was to determine the effect of the inclusion of Spirulina platensis hydrolyzed on the physiological state and growth in juveniles of Sparus aurata. A total of 180 individuals were fed for 128 days with three different feeds: control diet, diet with 2% of hydrolyzed microalgae (Sp2), and diet with 4% of hydrolyzed microalgae (Sp4).The experimental groups were tested in triplicate (except control group that was in duplicate). Biometric parameters were registered every two or three weeks. At the end of the experiment blood samples were collected to analyze plasma metabolites. After this we tried to evaluate the anti-oxidant response in animals remained from the first experiment using a toxicological assay with sodium nitrite lasting three days. Fish were divided into control, Spi 2% and Spi 4%, all them with and without NaNO2. Even then, the plasma metabolites data were collected after 24h and 72h. At the end of the first experiment the administration of S. platensis appeared to have a negative impact on growth of S. aurata respect the control feed. Furthermore, the lactate content registered showed a significant difference between the control and the spiruline administration. In the second experiment the spiruline feed showed a glucose and a lactate content with significant differences after 72h of exposition to nitrites respect the control group due to the interaction between nitrites and treatment. S. platensis hydrolyzed 2% and 4% do not seems a good substitution for S. aurata both as a growth enhancer and improver of health metabolic pathways. Its role as a good antioxidant has not been confirmed in these experiments.

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33

Castro, Marin Inmaculada. "Nitrate: metabolism and development : characterization of the glutamate dehydrogenase (GDH) family, an enzyme at the cross-roads of carbon-nitrogen interaction metabolites and study of the regulation of flowering by nitrogen." Phd thesis, Universität Potsdam, 2007. http://opus.kobv.de/ubp/volltexte/2008/1882/.

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The major aim of this thesis was to study the effect of nitrate on primary metabolism and in development of the model plant Arabidopsis thaliana. The present work has two separate topics. First, to investigate the GDH family, a small gene family at the interface between nitrogen and carbon metabolisms. Second, to investigate the mechanisms whereby nitrogen is regulating the transition to flowering time in Arabidopsis thaliana. To gain more insights into the regulation of primary metabolism by the functional characterization of the glutamate dehydrogenase (GDH) family, an enzyme putatively involved in the metabolism of amino acids and thus suggested to play different and essential roles in carbon and nitrogen metabolism in plants, knock out mutants and transgenic plants carrying RNA interference construct were generated and characterized. The effect of silencing GDH on carbon and nitrogen metabolisms was investigated, especially the level of carbohydrates and the amino acid pool were further analysed. It has been shown that GDH expression is regulated by light and/or sugar status therefore, phenotypic and metabolic analysis were developed in plants grown at different points of the diurnal rhythm and in response to an extended night period. In addition, we are interested in the effect of nutrient availability in the transition from vegetative growth to flowering and especially in nitrate as a metabolite that triggers widespread and coordinated changes in metabolism and development. Nutrient availability has a dramatic effect on flowering time, with a marked delay of flowering when nitrate is supplied (Stitt, 1999). The use of different mutants and transgenic plants impaired in flowering signalling pathways was crucial to evaluate the impact of different nitrate concentrations on flowering time and to better understand the interaction of nitrate-dependent signals with other main flowering signalling pathways. Plants were grown on glutamine as a constitutive source of nitrogen, and the nitrate supply varied. Low nitrate led to earlier flowering. The response to nitrate is accentuated in short days and in the CONSTANS deficient co2 mutant, whereas long days or overexpression of CONSTANS overrides the nitrate response. These results indicate that nitrates acts downstream of the known flowering signalling pathways for photoperiod, autonomy, vernalization and gibberellic acid. Global analyses of gene expression of two independent flowering systems, a light impaired mutant (co2tt4) and a constitutive over-expresser of the potent repressor of flowering (35S::FLC), were to be investigated under two different concentrations of nitrate in order to identify candidate genes that may be involved in the regulation of flowering time by nitrate.
Das Hauptziel dieser Doktorarbeit war die Untersuchung des Effekts von Stickstoff auf den Primärmetabolisms und auf die Entwicklung der Modellpflanze Arabidopsis thaliana. Die vorliegende Arbeit hat zwei Unterthemen: Auf der einen Seite wurde die GDH Familie untersucht, eine kleine Genfamilie an der Schnittstelle zwischen Stick –und Kohlenstoffmetabolismus. Auf der anderen Seite wurde der Mechanismus, bei dem Stickstoff die Blütezeit in Arabidopsis thaliana kontrolliert, untersucht. Um einen tieferen Einblick in die Regulierung des Primärmetabolismus zu erhalten, wurde eine funktionelle Charakterisierung der Glutamatdehydrogenase-Familie (GDH) mit Hilfe von knock-out Mutanten und transgenen Pflanzen, die ein RNA Interferenzkonstrukt tragen, durchgeführt. GDH ist höchstwahrscheinlich am Aminosäuremetabolismus beteiligt, wobei vermutet wird, dass es verschiedene wichtige Aufgaben im Pflanzenkohlen –und stickstoffmetabolismus übernimmt. Dabei wurde der Effekt des GDH Silencing auf den Kohlen- sowie Stickstoffmetabolismus untersucht und insbesondere die Anteile von Kohlenhydraten und Aminosäuren eingehend analysiert. In vorhergehenden Studien zeigte sich, dass die GDH-Expression durch Licht und/oder die Zuckerverfügbarkeit reguliert wird. Deshalb wurden phenotypische und metabolische Analysen an Pflanzen entwickelt, die zu verschiedenen Zeitpunkten des diurnalen Rhythmus und nach einer längeren Nachtperiode gezüchtet wurden. Ausserdem interesssiert uns der Effekt der Nährstoffverfügbarkeit im Übergang vom vegetativen Wachstum zur Blüte, und vor allen Dingen Nitrat als Metabolit, welches weitreichende und koordinierte Veränderungen im Metabolismus und in der Entwicklung hervorruft. Die Nährstoffverfügbarkeit hat einen dramatischen Effekt auf die Blütezeit, insbesondere führt eine Nitratzugabe zu einer deutlichen Verzögerung der Blüte (Stitt, 1999). Der Einsatz von verschiedenen Mutanten und transgenen Pflanzen, die eine Blockade im Blüte-Signalweg aufwiesen, war ausschlaggebend, um den Einfluss von unterschiedlichen Nitratkonzentrationen auf die Blütezeit zu beurteilen, und um zu einem besserem Verständnis des Zusammenspiels von nitratabhängigen Signalen und anderen Blüte-Signalwegen zu gelangen. Die Pflanzen wuchsen auf Glutamin, das als konstitutive Stickstoffquelle diente, wobei die Nitratversorgung variierte. Niedriger Nitratanteil führte zu einer früheren Blüte. Bei kurzer Tageslänge und bei CONSTANS defizienten Mutanten (co2) ist die Reaktion auf Nitratzugabe erhöht, wohingegen bei fortgeschrittener Tageslänge oder bei Überexpression von CONSTANS die Reaktion auf Nitrat unterbleibt. Diese Ergebnisse verdeutlichen, dass Nitrat unterhalb der bekannten Blüte-Signalwege für Photoperiode, Autonomie, Vernalisierung und Gibberelinsäure fungiert. Globale Expressionsanalysen von zwei unterschiedlichen Blütensystemen, eine licht-unempfindliche Mutante (co2tt4) und eine Mutante mit konstitutiver Expression eines potentiellen Blüte-Repressors (35S::FLC), wurden bei zwei verschiedenen Nitratkonzentrationen durchgeführt, um Kandidatengene zu identifizieren, die eine wichtige Rolle in der Regulation der Blütezeit durch Nitrat spielen könnten.

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34

Heuermann, Diana [Verfasser]. "Comparative analysis of phytohormone translocation, nitrogen metabolism and yield components under nitrate and urea nutrition in oilseed rape / Diana Heuermann." Halle, 2017. http://d-nb.info/1136608613/34.

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Bouton, Sophie. "Etude de la régulation transcriptionnelle de l'assimilation du nitrate chez Arabidopsis thaliana. Recherche de gènes régulateurs potentiels et caractérisation de mutants." Paris 6, 2001. http://www.theses.fr/2001PA066277.

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Guimarães, Luís Filipe Strobel. "Análise da expressão dos genes do metabolismo de nitrato nas estirpes SMR1 e DCP286A de Herbaspirillum Seropedicae por PCR em tempo real." reponame:Repositório Institucional da UFPR, 2012. http://hdl.handle.net/1884/27122.

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Resumo: O presente trabalho teve como objetivo quantificar a expressão de genes responsáveis pelo metabolismo de nitrato em H. seropedicae, estirpes SmR1 e DCP286A (ntrC-), por PCR quantitativo em tempo real. A quantificação dos níveis de expressão nas estirpes SmR1 e DCP286A demonstraram que o transportador de nitrato NasFED tem sua expressão dependente de nitrato, possivelmente controlada pela proteína NtrC e ativação dependente da proteína NasR. Os genes narK1UnarGHJI estão organizados em um operon e sua expressão depende de NtrC, da proteína FNR e ainda da proteína NarL. Os genes narKnirBDCnasA também estão organizados em um operon e sua expressão possivelmente está sob o controle de NtrC e de NasR. A expressão genes do sistema de dois componentes narXL parece ser dependente de NtrC, porém os sítios promotores encontrados são fracos. A expressão do gene nasR ainda não está clara, porém a presença de grampos terminadores de transcrição sugerem uma possível auto-regulação. A expressão do gene ntrY na estirpe SmR1 se demonstrou constitutiva e a diminuição da expressão na estirpe DCP286A sugere uma possível dependência da proteína NtrC para expressão de ntrY, porém os dados obtidos não são suficientes para elucidar o papel deste gene no metabolismo de nitrato em H. seropedicae.

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Santos, Carlos Leandro Rodrigues dos [UNESP]. "Atividade da redutase do nitrato em cana-de-açúcar." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/100825.

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Na primeira fase do estudo realizou-se, para cana-de-açúcar, a padronização das condições de determinação da atividade da enzima redutase do nitrato (RN). Além disso, procedeu-se um estudo para a caracterização da sua atividade em plantas da cultura. Na segunda etapa, acompanhou-se, ao decorrer do tempo após a aplicação de N, a variação dos níveis de atividade da RN em plantas de cana-de-açúcar deficientes do nutriente. Observou-se que a atividade da enzima é máxima aos 13 dias após a aplicação e que plantas deficientes em N, independente da fonte nitrogenada usada, apresentam o mesmo comportamento, e ainda, que a resposta enzimática é mais rápida com a aplicação de nitrato de amônio em relação à uréia ou sulfato de amônio. Na terceira fase, comparou-se cultivares de cana-de-açúcar quanto ao nível de atividade da RN e verificou-se sua relação com variáveis produtivas e nutricionais, tanto em condições controladas como no campo. Observou-se que a atividade da RN varia com a cultivar e que existe relação entre a atividade da enzima e o teor de N, e ainda, que teores de nitrato foliar não se associam com a atividade da enzima. Na última fase da pesquisa, estudou-se o efeito da dose de N na atividade da enzima RN. Os resultados sugeriram que em plantas com severa deficiência de N, a atividade da RN é influenciada pela dose. Constatou-se que, devido aos baixos teores de nitrato foliar, não há atividade da RN sem a adição de nitrato no meio reacional e que, a atividade da enzima apresenta boas perspectivas para indicar a nutrição nitrogenada de plantas de cana-de-açúcar, porém, ainda existe a necessidade do estabelecimento de um critério para o diagnóstico
In the first phase of the study was held, for sugarcane, the standardization of the conditions for determining the nitrate reductase activity (NR). Furthermore, a study was conducted for characterization of its activity in crop plants. In the second step, we accompanied, over time after N application, the variation in levels of NR activity in sugarcane plant N deficient. It was observed that the enzyme activity is maximal after 13 days of application and in plants deficient in N, independent of the N source used, plants show the same behavior, and that the enzymatic response is faster with the application of ammonium nitrate than urea or ammonium sulfate. In the third phase, we compared sugarcane cultivars in the level of NR activity and was verified its relationship with productive and nutritional variables, under controlled conditions and field. It was observed that NR activity varies with the cultivar and that there is a relationship between the enzyme activity and N content. Also, that the nitrate foliar was not associated with the enzyme activity. In the last phase of the research, we studied the effect of N application in enzyme NR activity. The results suggested that in plants with severe deficiency of N, NR activity is influenced by rate. It was found that due to the low levels of nitrate in the leaf does not occur increase of RN activity without the addition of nitrate in the reaction medium and that enzyme activity shows goods perspectives for indicate nitrogen nutrition of sugarcane plants, however, there is necessity of the establishment of a criterion for the diagnostic

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38

Santos, Carlos Leandro Rodrigues dos. "Atividade da redutase do nitrato em cana-de-açúcar /." Jaboticabal, 2013. http://hdl.handle.net/11449/100825.

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Orientador: Jairo Osvaldo Cazetta
Coorientador: Luciana Maria Saran
Banca: Milton Ferreira de Moraes
Banca: Samira Domingues Carlin Cavallari
Banca: Renato de Mello Prado
Banca: Fábio Oliviere de Nobile
Resumo: Na primeira fase do estudo realizou-se, para cana-de-açúcar, a padronização das condições de determinação da atividade da enzima redutase do nitrato (RN). Além disso, procedeu-se um estudo para a caracterização da sua atividade em plantas da cultura. Na segunda etapa, acompanhou-se, ao decorrer do tempo após a aplicação de N, a variação dos níveis de atividade da RN em plantas de cana-de-açúcar deficientes do nutriente. Observou-se que a atividade da enzima é máxima aos 13 dias após a aplicação e que plantas deficientes em N, independente da fonte nitrogenada usada, apresentam o mesmo comportamento, e ainda, que a resposta enzimática é mais rápida com a aplicação de nitrato de amônio em relação à uréia ou sulfato de amônio. Na terceira fase, comparou-se cultivares de cana-de-açúcar quanto ao nível de atividade da RN e verificou-se sua relação com variáveis produtivas e nutricionais, tanto em condições controladas como no campo. Observou-se que a atividade da RN varia com a cultivar e que existe relação entre a atividade da enzima e o teor de N, e ainda, que teores de nitrato foliar não se associam com a atividade da enzima. Na última fase da pesquisa, estudou-se o efeito da dose de N na atividade da enzima RN. Os resultados sugeriram que em plantas com severa deficiência de N, a atividade da RN é influenciada pela dose. Constatou-se que, devido aos baixos teores de nitrato foliar, não há atividade da RN sem a adição de nitrato no meio reacional e que, a atividade da enzima apresenta boas perspectivas para indicar a nutrição nitrogenada de plantas de cana-de-açúcar, porém, ainda existe a necessidade do estabelecimento de um critério para o diagnóstico
Abstract: In the first phase of the study was held, for sugarcane, the standardization of the conditions for determining the nitrate reductase activity (NR). Furthermore, a study was conducted for characterization of its activity in crop plants. In the second step, we accompanied, over time after N application, the variation in levels of NR activity in sugarcane plant N deficient. It was observed that the enzyme activity is maximal after 13 days of application and in plants deficient in N, independent of the N source used, plants show the same behavior, and that the enzymatic response is faster with the application of ammonium nitrate than urea or ammonium sulfate. In the third phase, we compared sugarcane cultivars in the level of NR activity and was verified its relationship with productive and nutritional variables, under controlled conditions and field. It was observed that NR activity varies with the cultivar and that there is a relationship between the enzyme activity and N content. Also, that the nitrate foliar was not associated with the enzyme activity. In the last phase of the research, we studied the effect of N application in enzyme NR activity. The results suggested that in plants with severe deficiency of N, NR activity is influenced by rate. It was found that due to the low levels of nitrate in the leaf does not occur increase of RN activity without the addition of nitrate in the reaction medium and that enzyme activity shows goods perspectives for indicate nitrogen nutrition of sugarcane plants, however, there is necessity of the establishment of a criterion for the diagnostic
Doutor

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39

Gomes, Valeria Aguiar 1982. "Efeitos do exercicio aerobio na formação de oxido nitrico em pacientes com sindrome metabolica." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/310011.

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Orientador: Jose Eduardo Tanus dos Santos
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
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Resumo: A síndrome metabólica (MetS) consiste em um conjunto de fatores de risco para doenças cardiovasculares. O óxido nítrico (NO) exerce papel fundamental na manutenção da homeostase cardiovascular. Portanto, a avaliação da biodisponibilidade do NO é de grande interesse clínico, pois possibilita a avaliação clínica da função vascular. A hipótese deste estudo é que o exercício aeróbio regular aumente a produção de NO em indivíduos com MetS. Para abordar esta questão, foram estudados 48 indivíduos sedentários, dos quais 20 indivíduos eram saudáveis (controles) e 28 pacientes com MetS. Dezoito pacientes com MetS foram submetidos a um período de 3 meses de exercício. Medimos as concentrações de nitrito no sangue total e no plasma, pelo método de quimioluminescência, em todos os participantes e depois do exercício no grupo com MetS. Além disso, avaliamos a concentração plasmática de guanosina monofosfato cíclica (GMPc), um segundo mensageiro, e dimetilarginina assimétrica (ADMA), um inibidor endógeno da óxido nítrico sintase, utilizando ensaios imunoenzimáticos comerciais. Para avaliar o estresse oxidativo, medimos as concentrações de substâncias reativas ao ácido tiobarbitúrico (TBA-RS) utilizando método fluorimétrico. Os resultados revelaram que o exercício não produziu alterações significativas nas concentrações plasmáticas de nitrito nos pacientes com MetS, mas as concentrações de nitrito no sangue total aumentaram significativamente após o exercício no grupo com MetS. Também neste grupo, observou-se que, a concentração de GMPc aumentou significativamente após o exercício, mas a concentração de ADMA e TBA-RS diminuíram. Nossos resultados sugerem que o exercício aeróbio aumenta a produção de NO em pacientes com MetS proporcionando efeitos benéficos ao sistema cardiovascular.
Abstract: The metabolic syndrome (MetS) denotes a clustering of cardiovascular risk factors. The nitric oxide (NO) is plays a pivotal role in the maintenance of cardiovascular homeostasis. The measurement of nitric oxide (NO) bioavailability is of great clinical interest in the assessment of vascular health. We hypothesized that regular aerobic exercise training increase NO production in individuals with MetS. To address this issue, we studied 48 sedentary individuals, 20 healthy subjects (controls) and 28 patients with MetS. Eighteen of those with MetS were subjected to a 3 months of exercise training. We measured by ozone-based chemiluminescence the whole blood and plasma nitrite concentration in all participants, including before and after training in MetS group. In addition, we assessed the plasma concentration of cyclic guanosine monophosphate (cGMP), a second messenger of NO, and asymmetrical dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, using commercial enzyme immunoassay. To evaluate oxidative stress we measured thiobarbituric acid reactive substances (TBA-RS) concentrations using fluorometric method. The results revealed that exercise training produced no significant changes in plasma nitrite concentrations in patients with MetS, but the whole blood nitrite concentrations significantly increased after training in MetS group. Also in this group we observed that, the cGMP concentration significantly increased but the concentration of ADMA, and TBA-RS decreased. Our findings suggest that aerobic exercise increases NO production in patients with metabolic syndrome providing beneficial effects on cardiovascular system.
Mestrado
Mestre em Farmacologia

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40

Rebelo, Lucas Rocha. "Influência de nitrato encapsulado e enxofre na dieta sobre metabolismo e emissão de metano em bovinos /." Jaboticabal, 2017. http://hdl.handle.net/11449/151072.

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Orientador: Telma Teresinha Berchielli
Coorientador: Juliana Duarte Messana
Banca: Marcia Helena Machado Rocha Fernandes
Banca: Rafael Canonenco de Araújo
Resumo: Este estudo objetivou avaliar o efeito da substituição da fonte de proteína verdadeira e da ureia por nitrato encapsulado (En) e enxofre (S) elementar sobre consumo, digestibilidade, parâmetros ruminais, eficiência de síntese de proteína microbiana e emissão de CH4 em bovinos Nelore. Foram utilizados cinco novilhos Nelore (352.7 ± 38.4 kg PV) canulados no rumen, e distribuídos em um delineamento em quadrado latino 5 × 5 (5 tratamentos e 5 períodos, 21 dias cada). O volumoso utilizado foi feno de Tifton 85 e o concentrado basal foi composto por milho, farelo de soja, e suplemento mineral comercial. Ureia, En e S foram adicionados para compor demais dietas. Os tratamentos foram: farelo de soja (SBM) como tratamento controle; ureia (U); U mais S elementar (US); nitrato encapsulado (EN); e EN mais S elementar (ENS). O En foi incluído nos tratamentos EN e ENS em 2% da MS (1,42% de NO3 - ânion), enquanto que a inclusão de ureia nos tratamentos U e US foi de 0,8% na MS da dieta. A inclusão de S nos tratamentos U e EN foi em 0,24% da MS, e a relação N:S foi reduzida de 8:1 para 4:1 com a adição de S. O En foi incluído gradualmente de 0,5% até 2% da MS da dieta. Os contrastes ortogonais para avaliar os efeitos de tratamento foram: SBM vs. EN + ENS; U + US vs. EN + ENS; U vs. US; e EN vs. ENS. Os novilhos apresentaram baixos níveis de MetHb (média de 1,1%) a medida em que a quantidade de En foi aumentada. O consumo de OM e NDF foram menores (P ≤ 0,01) para os animais alimentados com En... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The objective of this study was to investigate the replacement of true protein source as well as the conventional NPN source (urea) by encapsulated NO3 - (En) plus elemental sulfur (S) on microbial protein synthesis efficiency, and CH4 emission in Nellore beef cattle. Five ruminally-cannulated Nellore steers (352.7 ± 38.4 kg BW) were used in a 5 × 5 Latin square design with 5 periods of 21 d each. Tifton 85 hay was used as forage and the basal concentrate consisted of corn, soybean meal, and commercial mineral supplement (50:50 wt/wt, forage:concentrate). Urea, En and S were added to compose the other diets. The treatments were: true protein from soybean meal as control (SBM); urea (U); U plus elemental S (US); encapsulated NO3 - (EN); and EN plus elemental S (ENS). En was included in 2% on dietary DM (1.42% NO3 - anion), while the inclusion of urea in U and US diets was 0.8% on dietary DM. The inclusion of S for U and EN diets was 0.24% on dietary DM, and the N:S ratio was reduced from 8:1 to 4:1 with the addition of S. En was gradually included from 0.5 to 2% on dietary DM by 0.5% every 4 d. The orthogonal contrasts for specific partitioning of treatment effects were: SBM vs. EN + ENS; U + US vs. EN + ENS; U vs. US; and EN vs. ENS. Steers displayed adequate MetHb levels as dietary En content increased. Organic matter and aNDF intake were smaller (P ≤ 0.01) for animals fed En diets compared to SBM. Digestibility of DM, OM, and GE were greater (P ≤ 0.01) when fed En diets com... (Complete abstract click electronic access below)
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41

Junior, João Cardoso de Souza. "Suprimento de nitrato e amônio e a tolerância do capim tanzânia ao estresse por excesso de cobre." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-18052017-142834/.

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O suprimento de proporções de nitrato (NO3-) e amônio (NH4+) no meio de crescimento pode otimizar o metabolismo e o crescimento do Panicum maximum. A toxidez de cobre (Cu) causa estresse oxidativo nas plantas, afetando o metabolismo, a fotossíntese e a produção de massa. Não há pesquisas associando proporções de NO3-/NH4+ no alívio do estresse por Cu em plantas. O objetivo foi avaliar o efeito da toxidez de Cu no metabolismo, nutrição mineral, fotossíntese e produção do capim tanzânia, assim como o papel de proporções de NO3-/NH4+ no alívio dessa toxidez. O delineamento experimental foi de blocos ao acaso em arranjo fatorial 3×4 com seis repetições, sendo três destinadas à avaliação dos atributos metabólicos e fisiológicos e outras três aos atributos nutricionais e produtivos. Os fatores empregados foram: proporções de NO3-/NH4+ (100/0; 70/30 e 50/50) combinadas com doses de Cu (0,3; 250; 500 e 1000 μmol L-1) em solução nutritiva. Foram avaliados dois períodos de crescimento das plantas, sendo o primeiro com exposição ao Cu e o segundo sem exposição ao Cu. No primeiro corte as plantas supridas com 70/30 de NO3-/NH4+ e Cu de 1000 μmol L-1 apresentaram maior concentração de Cu nas folhas recém-expandidas (LR) e maior acúmulo de Cu na biomassa, maior concentração de NH4+ nas LR, maior acúmulo de NH4+ na parte aérea, maior atividade da glutamina sintetase nas LR, maior concentração de prolina nas LR, maior atividade da enzima superóxido dismutase (SOD) nas partes do capim e menor produção de biomassa. No capim suprido com 100/0 de NO3-/NH4+ e Cu de 1000 μmol L-1 foram obtidos menor concentração de Cu nas LR e menor acúmulo de Cu na parte aérea, mas a concentração e o acúmulo desse metal nas raízes foram incrementados mesmo nas mais baixas doses de Cu. As plantas crescidas com N na forma de NO3- ainda apresentaram maior concentração de NO3- nas LR, maior acúmulo de NO3- nas raízes, maior acúmulo de N total, maior atividade da nitrato redutase nas LR, maior condutância estomática e maior produção de biomassa. No capim recebendo 100/0 de NO3-/NH4+ também ocorreu menor atividade da SOD e menor concentração de prolina nas partes da planta. A concentração de malondialdeído foi menor na mais elevada dose de Cu, assim como a taxa de transpiração, a eficiência do fotossistema II, a taxa de transporte de elétrons e a taxa de assimilação de CO2. A atividade da catalase, guaiacol peroxidase, ascorbato peroxidase e glutationa redutase foram ativadas principalmente nas raízes, sendo maiores na mais elevada dose de Cu. A toxidez de Cu afeta negativamente o metabolismo, a nutrição mineral, a fisiologia e a produção do capim tanzânia, mas as proporções de NO3-/NH4+ alteram essa toxidez. O emprego de N na forma de NO3- é estratégia de maior potencial de uso em plantas com elevado estresse por Cu. Entretanto, a combinação de NO3- ao NH4+ no meio de crescimento em situação de moderado estresse por Cu é estratégica para maior fitoextração desse metal.
The supply of nitrate (NO3-) and ammonium (NH4+) proportions in the growth medium can optimize the metabolism and growth of Panicum maximum. Copper (Cu) toxicity causes oxidative stress in plants, affecting metabolism, photosynthesis and biomass production. There are no researchs associating proportions of NO3-/NH4+ for alleviating Cu stress toxicity. The objective was to evaluate the effect of Cu toxicity on metabolism, mineral nutrition, photosynthesis and dry matter production, as well as the role of NO3-/NH4+ proportions in alleviating such toxicity. The experimental was carried out in randomized complete block design in a 3×4 factorial with six replications. Three replications were used to evaluated metabolic and physiological attributes and other three to determine nutrition and productive attributes. The factors were three proportions of NO3-/NH4+ (100/0, 70/30 and 50/50) combined with four rates of Cu (0.3, 250, 500 and 1000 μmol L-1) in nutrient solution. Two plant growth periods evaluated, being the first with plants exposure to Cu and the second without the exposure to Cu. In the first cut, plants supplied with 70/30 of NO3-/NH4+ proportions and Cu rates of 1000 μmol L-1 showed high Cu concentration in recently fully expanded leaf laminae (LR), high Cu accumulation in the biomass, high NH4+ concentration in LR, high NH4+ accumulation in shoots, high glutamine synthetase activity in LR, higher proline concentration in LR, high superoxide dismutase (SOD) activity in parts of grass and low shoot dry matter production. In the grass supplied with 100/0 of NO3-/NH4+ and Cu of 1000 μmol L-1 it was found a low Cu concentration in LR and low Cu accumulation in shoots, but the concentration and accumulation of this metal in roots were increased even in lower Cu rate. Plants supply with 100/0 of NO3-/NH4+ also showed high NO3- concentration in LR, high NO3- accumulation in roots, high N accumulation in shoots, high nitrate reductase activity in LR, high stomatal conductance and high biomass production. In the grass supplied with 100/0 of NO3-/NH4+, there was low SOD activity and low proline concentration in shoots. The concentration of malondialdehyde was low at the high Cu rate, as well as the transpiration rate, photosystem II efficiency, electron transport rate and CO2 assimilation rate. Catalase, guaiacol peroxidase, ascorbate peroxidase and glutathione reductase activities were activated mainly in roots, being high in high Cu rate. Cu toxicity negatively affects metabolism, mineral nutrition, physiology and dry matter productions of tanzania guineagrass, but NO3-/NH4+ proportions change this toxicity. The only use of NO3- in the N supply is a strategy of great potential to be use in plants with of high Cu stress. However, combinations of NO3- with NH4+ in the growth medium when plants suffer moderate Cu stress is strategic for great metal phytoextraction.

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42

FAIT, GABRIELLA. "Monitoraggio della percolazione di erbicidi e nitrati nelle acque sotterranee." Doctoral thesis, Università Cattolica del Sacro Cuore, 2008. http://hdl.handle.net/10280/248.

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Lo scopo principale di questa ricerca è stato di monitorare la concentrazione di nitrati, dell'erbicida terbutilazina e di un suo metabolita, la desethylterbuthylazina, in acque sotterranee superficiali, secondo le normali pratiche agronomiche in differenti aree italiane rappresentative della coltura maidicola. Il primo passo è stato identificare i siti di monitoraggio, quindi è stata creata una procedura generale al fine di individuare aree rappresentative per il mais in Italia. Dentro tali aree sono stati selezionati dei siti di: 4 in Lombardia, 2 in Emilia Romagna, 2 in Veneto, 2 in Piemonte e uno in Friuli-Venezia Giulia. In Aprile 2005 il monitoraggio ha avuto inizio e i campionamenti sono stati eseguiti ogni due mesi. L'indice “IDPR”, strumento per la mappatura della vulnerabilità a livello regionale e nazionale, è stato applicato alle aree oggetto di studio. L'indice riflette l'influenza che le formazioni geologiche del sottosuolo hanno sullo scorrimento superficiale e sull'infiltrazione. L'analisi della probabilità di distribuzione dei risultati ha mostrato che una bassa probabilità di superare i limiti fissati per legge, questa probabilità è risultata più alta per il metabolita. Le concentrazioni dei nitrati nelle acque sotterranee sono risultate molto basse. Inoltre, è stato applicato un modello matematico (MACRO vs 5.1) di previsione che calcola la percolazione dei pesticidi.
The main aim of the research was to monitor the concentrations of nitrates, the herbicide terbuthylazine and its products of the environmental degradation, desethyl-terbuthylazine, in shallow groundwater, according to the normal agricultural practices in different Italian areas representative of maize crop. The first step was to identify the monitoring sites, therefore it was necessary to create a general procedure to individuate maize representative areas in Italy. Inside these area 11 monitoring sites were selected: 4 in Lombardy, 2 in Emilia Romagna, 2 in Veneto, 2 in Piedmont and one in Friuli-Venezia Giulia. In April 2005 the monitoring started. Groundwater samplings were carried out every two months. The IDPR index, a tool for national and regional vulnerability mapping, was applied. The index reflects the influence of the subsurface geological formations on the surface water runoff or infiltration. The distribution probability analysis of the results showed that there was a very low probability of exceeding the limit fixed by law, this probability was higher for the metabolite. The greater probability of exceed the 0.1 μg/L occurred in two sites, both irrigated with basin irrigation system. Nitrate concentrations resulted to be very low in shallow groundwater. Moreover, it was used a mathematical model which calculate the leaching of pesticides (MACRO 5.1).

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CHARPIN, MARIE-FRANCOISE. "Les activites enzymatiques nitrate-reductase, glutamine-synthetase et glutamate-deshydrogenase : interets pour l'etude du metabolisme de l'azote mineral des peuplements phytoplanctoniques lacustres." Clermont-Ferrand 2, 1997. http://www.theses.fr/1997CLF21936.

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Dans l'optique d'une meilleure comprehension du metabolisme de l'azote mineral des communautes phytoplanctoniques lacustres, nous avons mesure l'activite de trois enzymes clefs du metabolisme de cet element chimique : la nitrate-reductase (nr), la glutamine-synthetase (gs) et la glutamate deshydrogenase (gdh). Une etude comparee a ete realisee entre un ecosysteme eutrophe, le lac d'aydat et un ecosysteme oligomesotrophe, le lac pavin. La nr et la gdh presentent les caracteristiques d'enzymes inductibles alors que la gs semble constitutive. Ainsi, conformement aux resultats rapportes dans la litterature, la voie principale d'assimilation de l'ammonium dans le pool d'acides amines intracellulaires semble etre la voie gs/gogat. L'apparition des activites nr et gdh ne peut etre reliee directement avec les teneurs en elements nutritifs azotes dans le milieu. Cependant, l'activite specifique de ces trois enzymes depend non seulement des concentrations en ammonium et nitrates dans le milieu et de leur rapport mais egalement de la composition specifique des peuplements phytoplanctoniques et de leur metabolisme photosynthetique. Les rapports d'activite nr/gs et nr/gs+gdh ne permettent pas de determiner la part potentiellement representee par les nitrates ou l'ammonium dans la nutrition minerale azotee du phytoplancton. En effet, les mesures des activites enzymatiques potentielles refletent plus les capacites maximales de reduction des nitrates ou d'assimilation de l'ammonium des communautes phytoplanctoniques que les taux physiologiques de ces processus in situ. De plus, les parametres etudies ne permettent pas de determiner si la gdh fonctionne dans le sens anabolique ou catabolique. La methode isotopique indirecte utilisee afin d'estimer l'absorption de l'azote mineral par le phytoplancton semble largement surestimer cette derniere. Aussi, la comparaison de ces estimations avec les activites gs et gs+gdh ne permet pas d'affirmer que la mesure de ces activites enzymatiques permet de quantifier l'assimilation de l'azote mineral par les communautes phytoplanctoniques lacustres. Les peuplements phytoplanctoniques du lac pavin, soumis a une limitation relative en azote plus importante qu'au lac d'aydat, s'adaptent a ces contraintes environnementales. Ils presentent une activite nr leur permettant de metaboliser la forme d'element nutritif azote la plus abondante dans cet ecosysteme (les nitrates) et l'activite specifique de la gs est augmentee. Cependant, la seule determination des activites specifiques de la nr, de la gs et de la gdh ne semble pas constituer un indicateur de l'etat nutritionnel des communautes phytoplanctoniques par rapport a l'azote.

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Masakapalli, Shyam Kumar. "Network flux analysis of central metabolism in plants." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:ac8b3836-9ab7-4060-b50a-df8aaa0e4ba5.

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The aim of this thesis was to develop stable-isotope steady-state metabolic flux analysis (MFA) based on ¹³C labeling to quantify intracellular fluxes of central carbon metabolism in plants. The experiments focus on the analysis of a heterotrophic cell suspension culture of Arabidopsis thaliana (L) Heynh. (ecotype Landsberg erecta). The first objective was to develop a robust methodology based on combining high quality steady-state stable labeling data, metabolic modeling and computational analysis. A comprehensive analysis of the factors that influence the outcome of MFA was undertaken and best practice established. This allowed a critical analysis of the subcellular compartmentation of carbohydrate oxidation in the cell culture. The second objective was to apply the methodology to nutritional perturbations of the cell suspension. A comparison of growth on different nitrogen sources revealed that transfer to an ammonium-free medium: (i) increased flux through the oxidative pentose phosphate pathway (oxPPP) by 10% relative to glucose utilisation; (ii) caused a substantial decrease in entry of carbon into the tricarboxylic acid cycle (TCA); and (iii) increased the carbon conversion efficiency from 55% to 69%. Although growth on nitrate alone might be expected to increase the demand for reductant, the cells responded by decreasing the assimilation of inorganic N. Cells were also grown in media containing different levels of inorganic phosphate (Pi). Comparison of the flux maps showed that decreasing Pi availability: (i) decreased flux through the oxPPP; (ii) increased the proportion of substrate fully oxidised by the TCA cycle; and (iii) decreased carbon conversion efficiency. These changes are consistent with redirection of metabolism away from biosynthesis towards cell maintenance as Pi is depleted. Although published genome-wide transcriptomic and metabolomic studies suggest that Pi starvation leads to the restructuring of carbon and nitrogen metabolism, the current analysis suggests that the impact on metabolic organisation is much less extreme.

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Freire, Ana Paula Alves. "Desempenho, características de carcaça, produção de metano e metabolismo ruminal em ovinos alimentados com dietas contendo nitrato de cálcio." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11139/tde-11122015-165955/.

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Quatro experimentos foram realizados para estudar o desempenho, produção de metano e metabolismo ruminal em ovinos alimentados com dietas contendo nitrato de cálcio (NC). Experimento 1: Cinquenta borregas foram utilizadas, em delineamento em blocos completos casualizados, para avaliar o desempenho, as características de carcaça e a produção de CH4. As dietas continham teores crescentes (0, 1, 2, 3 ou 4% na MS) de NC. Houve efeito quadrático para consumo de MS, peso final, ganho médio diário e eficiência alimentar. O aumento do consumo de NC promoveu redução da produção de CH4. O peso ao abate, peso da carcaça quente e fria e espessura da parede corporal reduziram linearmente. Houve efeito quadrático para a espessura de gordura, área de olho de lombo e para a luminosidade. A inclusão de NC reduz a produção de metano, no entanto, em teores a partir de 2%, reduz o consumo, o ganho médio diário e a eficiência alimentar. Em teores de até 4% de NC não alterou os valores de NaNO3 e NaNO2 na carne fresca. Experimento 2: Cinco ovinos canulados no rúmen, distribuídos em delineamento em quadrado latino, foram utilizados para avaliar o metabolismo ruminal, digestibilidade e balanço de N. As dietas continham teores crescentes (0, 1, 2, 3 ou 4% na MS) de NC encapsulado. Houve efeito quadrático para o consumo de MS, consumo de água/kg MS e N retido. Houve efeito linear crescente para a digestibilidade da MO, da FDN e da PB. Houve efeito linear decrescente para o N fecal. Houve efeito quadrático para a concentração de AGCC total e para a proporção molar de ácido valérico. Houve efeito linear crescente para a proporção de ácido acético, butírico e isobutírico. Houve efeito quadrático para o N-NH3 e aumento linear para o pH ruminal. O NC encapsulado até teores de 4% para ovinos aumenta a digestibilidade dos nutrientes e da fibra insolúvel em detergente neutro, o pH ruminal e a proporção de ácido acético em relação a concentração de AGCC. No entanto o consumo é reduzido quando o NCE é adicionado em teores de 4%. Experimentos 3 e 4: foram realizados em delineamento em blocos completos casualizados para avaliar dietas contendo diferentes fontes de nitrogênio: farelo de soja (controle), ureia, nitrato de cálcio encapsulado (NCE) e nitrato de cálcio não encapsulado (NCNE). Em ambos os experimentos analisou-se os contrastes: controle vs nitrogênio nãoproteico (ureia, NCE e NCNE), ureia vs nitrato de cálcio (NCE e NCNE) e NCE vs NCNE. No experimento 3 foram utilizados 44 cordeiros para determinar os efeitos de diferentes fontes de nitrogênio nas características de desempenho e de carcaça. O peso final, o ganho médio diário e a eficiência alimentar foram maiores no controle em relação ao NNP. No experimento 4 foram utilizados 20 ovinos machos castrados, canulados no rúmen, para avaliar o metabolismo ruminal e a digestibilidade dos nutrientes. A digestibilidade da FDN foi maior nas dietas contendo NNP em relação à dieta controle. O pH ruminal foi maior nas dietas com NNP em relação ao controle; e maior no NC em relação a dieta com ureia. O ácido acético foi maior nas dietas com NC em relação a dieta com ureia. O ácido propiônico foi maior com NNP comparados à dieta controle e menor nas dietas com NC comparada à dieta com ureia. A relação acetato: propionato foi maior no NC em relação à ureia. A inclusão de 2% do íon nitrato, tanto na forma de NCE como NCNE para ovinos, permite que o desempenho e características de carcaça sejam similares a dieta com inclusão de 1,1% de ureia. O NC influencia no aumento da digestibilidade da fibra em detergente neutro, do pH ruminal, da proporção de acetato em relação a concentração de AGCC total e da relação Ac:Pr.
Four experiments were conducted to study the performance, methane production and ruminal metabolism in sheep fed diets containing calcium nitrate (CN). Experiment 1: Fifty ewe lambs were used, in a randomized complete block design, to determine the performance, carcass characteristics and methane production. Diets contained increasing levels (0, 1, 2, 3 or 4%, DM basis) of CN. There was a quadratic effect on dry matter intake, final body weight, average daily gain and feed efficiency. Increased CN intake promoted reduction in methane production. Slaughter weight, hot carcass weight and chilled carcass weight reduced linearly. There were a quadratic effect on the fat thickness, rib eye area and for brightness. Increased CN reduces the production of methane, however, in amounts from 2% reduces intake, average daily gain and feed efficiency. In amounts of up to 4% did not change NaNO3 and NaNO2 in fresh meat. Experiment 2: Five sheep, cannulated in the rumen, distributed in a Latin Square design, were used to determine ruminal metabolism and digestibility. There was a quadratic effect for DM intake, water intake/kg DM and N retained. There was a linear increase for the digestibility of OM, NDF and CP, while fecal N decreased linearly. There was a quadratic effect on the concentration of the total SCFA and the molar proportion of valeric acid. There was a linear effect on the proportion of acetic acid, butyric acid and isobutyric acid. There was a quadratic effect for N-NH3 while ruminal pH increased linearly. The encapsulated CN up to 4% in sheep increases the digestibility of the nutrients and insoluble in neutral detergent fiber, ruminal pH and the proportion of acetic acid relative concentration of SCFA. However intake is reduced when the encapsulated CN is added at 4%. Experiments 3 and 4: were conducted in a randomized complete block design to evaluate diets containing different nitrogen sources: soybean meal (control), urea, encapsulated calcium nitrate (ECN) and nonencapsulated calcium nitrate (NECN). In both experiments were analyzed the following contrasts: control vs non-protein nitrogen (urea, ECN and NECN), urea vs calcium nitrate (ECN and NECN) and ECN vs NECN. In Experiment 3, 44 ram lambs were used to determine the effects of different nitrogen sources on performance and carcass traits. The final weight, average daily gain and feed efficiency were greater in the control diet compared to the NPN. In the experiment 4, 20 wethers, cannulated in the rumen, were used to assess the rumen metabolism and diets digestibility. The NDF digestibility was greater in diets containing NPN compared to the control. The ruminal pH was higher in the NPN diets compared to the control; and greater in the diets with NC than those with urea. The acetic acid was higher in diets with CN than the urea diet. The propionic acid was higher in the NPN diets compared to the control and lower in CN compared to the urea diet. The acetate: propionate ratio was higher for diets with CN compared to the urea diet. CN influences the increased digestibility of neutral detergent fiber, ruminal pH, the proportion of acetate relative to the total SCFA concentration and the relationship Ac: Pr.

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46

George, Mary. "Urea and Non-Protein Nitrogen Metabolism in Infants : With Special Reference to the Sudden Infant Death Syndrome (SIDS)." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-5141-1/.

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47

Ben, Mrid Reda. "Perception, transport et assimilation de l'azote chez deux écotypes marocains de sorgho : caractérisation phénotypique, biochimique et moléculaire." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066604.

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Notre étude a consisté d'abord, en un travail de caractérisation moléculaire du gène SBNRT1.1 codant pour un transporteur de nitrate et présent en 3 copies chez le sorgho. Nous avons donc analysé leur structure et leur expression dans différents organes de la plante. Une analyse de leurs séquences nucléotidiques et protéiques a été également conduite. Notre étude a montré que les 3 co-orthologues (SBNRT1.1A, B et C) sont exprimés aussi bien dans les feuilles que dans les tiges et les racines du sorgho. Par ailleurs, nous avons révélé, pour la première fois, l'existence de 5 transcrits, de taille variable pour le gène SBNRT1.1B. Dans un autre volet, l'analyse des paramètres de croissance et d'activités enzymatiques clés dans les métabolismes azoté et carboné chez deux écotypes de sorgho connus pour leur différence de croissance dans des conditions de cultures différentes en apport azote, a montré que ces plantes de sorgho se caractérisent par une capacité à croitre à des niveaux élevés d'apports en azote, avec une réponse différentielle des deux écotypes. Cette tolérance s'est manifestée par une accumulation de chlorophylle, d'acides aminés et de protéines. D'autre part, les activités enzymatiques d'enzymes clés des métabolismes azoté et carboné, semblent être liées a la capacité des plantes de sorgho à faire face au stress azoté. Nos résultats pourraient ainsi fournir un cadre initial pour l'identification de marqueurs biochimiques qui pourraient contribuer utilement à la sélection des génotypes utilisant l'azote plus efficacement et donnant un rendement en biomasse et /ou grain, plus élevé, même dans des conditions de stress azoté
Our study consisted firstly, in the molecular characterization of SbNRT1.1 gene, coding for a nitrate transporter and present in three copies in sorghum plants. We report here their structure and expression patterns in different organs of sorghum. We have also conducted a comparison of their nucleotide and polypeptide sequences with orthologous sequences from other species. Our study showed that the 3 co-orthologous (SbNRT1.1A, B and C) are expressed in leaves, stems and roots of sorghum. Moreover, we have for the first time revealed the existence of 5 alternative transcripts for the SbNRT1.1B gene. In another component of our research program, biochemical and physiological traits of two sorghum ecotypes differing in sensitivity to nitrogen were investigated and have shown that these sorghum plants are able to grow at high levels of nitrogen inputs, with differential response to nitrogen sources and rates. This tolerance was manifested by accumulation of high accumulation of chlorophyll, amino acids and protein. On the other hand, the enzymatic activities of certain key enzymes of nitrogen and carbon metabolisms, seem to be related to the capacity of sorghum plants to deal with nitrogen stress. Hence, our findings could provide an initial framework for the identification of biochemical markers for the selection of genotypes using nitrogen more efficiently and giving high yield of biomass and/or grain even under nitrogen stress conditions

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Bucher, Carlos Alberto. "Express?o de genes relacionados ? absor??o e metabolismo de nitrog?nio em arroz sob alto e baixo suprimento de nitrato." Universidade Federal Rural do Rio de Janeiro, 2011. https://tede.ufrrj.br/jspui/handle/jspui/1163.

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Funda??o Carlos Chagas Filho de Amparo ? Pesquisa do Estado do RJ - FAPERJ
Nitrogen is one of the nutrient elements most limiting for plant growth. Thus, increasing plant nitrogen usage efficiency (NUE) is an essential factor for sustainable agriculture, leading to an increased food production with less fertilizer input and less environment impact. NUE in plant involves the uptake and accumulation efficiency, and N use efficiency for grain production. Understanding the mechanisms regulating these processes is crucial for the improvement of NUE in crops. Therefore, is essential to comprehend plants response to different N regimes, mainly N limitation. The usage of plants or varieties with differences in nutrient use efficiency is another important factor to determine the main mechanisms involved in these processes. The objectives of this study were to evaluate N metabolism and expression of genes involved in N uptake and assimilitation of two rice varieties (Piau? and IAC-47), under different N supply conditions. The N metabolism was evaluated by quantification of nitrogen fractions in plant tissue and enzymatic activity, expression of genes that code for high and low affinity N transporters, and N assimilation enzymes. Two experiments were conducted: the first, to investigate the plants behavior when grown under high and low N supply; and the second to verify plants response to NO3 - resupply. The IAC-47 variety showed greatest mass accumulation in all treatments. When plants were grown for a long period under low N supply it was observed a higher nitrate (NO3 -) content in the tissue of Piau? variety, which is adapted to low fertility conditions, as well as a high activity of nitrate reductase and glutamine synthetase in the roots of these plants. When under high NO3 - supply for a long period, Piau? variety had higher NO3 - concentrations in roots and sheaths, but no differences were observed in enzymes activity. The nitrate transporters expression was higher in roots of Piau? plants under low supply of NO3 - when compared to Piau? plants under high N supply. Nitrate transporters expression in roots of IAC-47 plants showed a pattern opposite to the one observed for Piau? plants. When plants were resupplied with NO3 -, after a 72 hours period without N, there was a rapid increase, after 6 hours of resupply, in the expression of high affinity nitrate transporters genes (OsNRT2.1) and the plastidial glutamine synthetase (GS2) in the Piau? variety roots, and a higher expression of these in IAC-47 roots after a 24 hours of N resupply. The efficiency of Piau? variety is related to the differentiated control of N absorption and assimilation mechanisms, which allow bigger expression of high affinity nitrate transporters in tissue with high levels of soluble N, high N status, indicating that the control of nitrogen uptake system may be essential for the nitrogen usage efficient.
O nitrog?nio ? um dos elementos minerais que mais limita o desenvolvimento das plantas. Assim, aumentar a efici?ncia de uso de nitrog?nio (EUN) ? um fator ? essencial para uma agricultura sustent?vel, levando a um aumento da produ??o de alimentos com menor uso de insumos e menos impactos ao ambiente. A EUN envolve a efici?ncia de absor??o e ac?mulo e a efici?ncia de utiliza??o de N para produ??o. Compreender os mecanismos envolvidos nesses processos e como eles s?o controlados ? fundamental para a melhoria da EUN nas plantas cultivadas. Para isso, ? essencial entender a resposta e comportamento das plantas a diferentes regimes de N, principalmente ? limita??o de N. O uso de plantas ou variedades com diferen?as na EUN ? outro fator importante para verificar os principais mecanismos envolvidos. Este trabalho teve por objetivo desse trabalho foi verificar o metabolismo e a express?o de genes envolvidos na absor??o e assimila??o de nitrog?nio nas variedades de arroz Piau? e IAC-47 sob diferentes condi??es de disponibilidade desse nutriente. O metabolismo de N foi avaliado atrav?s da quantifica??o das fra??es nitrogenadas no tecido e atividade enzim?tica, a express?o de genes que codificam para transportadores de N de alta e baixa afinidade e enzimas de assimila??o de N. Foram realizados dois experimentos: o primeiro para verificar o comportamento das plantas quando cultivadas sob alto e baixo suprimento de N; e o segundo, para verificar as repostas ao ressuprimento de N. O ac?mulo de massa foi maior na variedade IAC-47 em todos os tratamentos. Quando as plantas foram cultivadas por um longo per?odo sob baixo suprimento de N foi observado maior teor de nitrato (NO3 -) no tecido da variedade Piau?, adaptada a condi??es de baixa fertilidade, assim como uma alta atividade da nitrato redutase e glutamina sintetase nas ra?zes dessas plantas. Sob alto suprimento de NO3 -, por um longo per?odo, a variedade Piau? apresentou maiores teores de NO3 - nas bainhas e ra?zes, mas n?o foram observas diferen?as na atividade de enzimas. A express?o dos transportadores de nitrato na variedade Piau? foi mais elevada nas ra?zes das plantas sob baixo suprimento de NO3 - quando comparado as plantas sob alto suprimento de N. Na variedade IAC-47 a express?o dos transportadores de NO3 - teve comportamento oposto ao observado para a Piau?. Quando as plantas receberam NO3 -, ap?s um per?odo de 72 horas sem N, houve um r?pido aumento, ap?s 6 horas do ressuprimento, na express?o do gene que codifica para o transportador de NO3 - de alta afinidade OsNRT2.1 e glutamina sintetase plastidial (GS2) nas ra?zes da variedade Piau?, e 24 horas ap?s o ressuprimento a express?o foi maior na variedade IAC-47. A efici?ncia da variedade Piau? esta relacionada ao controle diferenciado dos mecanismos de absor??o e assimila??o de N, que permite a maior express?o dos transportadores de nitrato de alta afinidade em tecido com altos teores de N sol?vel, alto status de N, indicando que o controle do sistema de absor??o de N pode ser essencial para a efici?ncia no uso de nitrog?nio.

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49

O'Brien, Katie Alice. "Investigation into metabolic profile changes in environmental hypoxia and the potential for dietary nitrate to alleviate hypoxic stress." Thesis, King's College London (University of London), 2017. https://kclpure.kcl.ac.uk/portal/en/theses/investigation-into-metabolic-profile-changes-in-environmental-hypoxia-and-the-potential-for-dietary-nitrate-to-alleviate-hypoxic-stress(26f38d92-b9b2-45f4-8231-b3c68da0575f).html.

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Oxygen (O2) insufficiency (hypoxia), either in response to environmental exposure or pathological states is a driver of metabolic remodelling, the details of which are ill- defined. This work aimed to further understanding of metabolic responses to environmental hypoxia. In the first study, plasma metabolite changes were measured in 198 human subjects upon ascent to Everest Base Camp (5300m) using metabolomic and lipidomic techniques. Results were indicative of a shift towards anaerobic glycolysis, a mobilisation of fat stores and alterations to fat lipoprotein transport with ascent. In the second study, a pilot study, subjects (n=5) were examined pre and post an attempted winter crossing of Antarctica, including a 24 week stay above 2,500m. Metabolomics analysis of serum samples alongside whole body physiological and exercise measurements were indicative of a shift in metabolic signature, including an increased reliance upon carbohydrate metabolism during exercise. Developing a means of attenuating the metabolic stress of hypoxia would be highly beneficial for aiding human adaptation and ameliorating the effects of disease states where hypoxia is a comorbidity. An additional aim was to explore the potential of dietary nitrate for this purpose. In the third study, the potential for nitrate supplementation to aid hypoxic acclimatisation of skeletal muscle mitochondria and the role of PPARα (a master regulator of fat oxidation) were assessed using a mouse model of wild type (n=42) and PPARα-/- strains (n=42). Nitrate supplementation (0.7mM) recovered hypoxic induced decreases in fatty acid and carbohydrate oxidation in response to prolonged, severe hypoxic exposure (10% O2, 28 days) and did so independently of PPARα. In the fourth study, the effects of acute dietary nitrate supplementation (12mM nitrate vs. placebo ingested 3 hours pre-exercise) upon exercise endurance and related metabolite changes were investigated in chronic obstructive pulmonary disease (COPD) patients (n=21, age 68+7 years). Whilst neither median endurance time nor targeted plasma metabolites differed between treatments, O2 consumption was significantly lower following nitrate treatment vs. placebo. The absence of plasma lactate changes between treatments indicates this effect was not mediated through increased reliance upon anaerobic metabolism. In conclusion, this work highlighted several potential biomarkers of interest in healthy humans exposed to environmental hypoxia, including alterations to carbohydrate and lipid metabolism. Dietary nitrate demonstrated potential for recovering metabolic function in vitro, yet failed to illicit beneficial effects in a clinical population in vivo.

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Nascimento, Rafaella Adalgisa Silva do. "Associação do polimorfismo da óxido nitrico endotelial (eNOS) T-786C com moléculas do metabolismo lipídico e inflamatório em amostras de mulheres grávidas." Universidade Federal de Pernambuco, 2013. https://repositorio.ufpe.br/handle/123456789/12225.

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A gestação é um fenômeno fisiológico que se inicia com a fecundação e progride no sentido de promover um ambiente adequado onde o feto possa crescer e formar um novo indivíduo com todo seu potencial genético expresso. Durante este período, os níveis lipídicos normalmente aumentam para permitir a manutenção da homeostase entre mãe e feto. Níveis lipídicos anormais estão relacionados com disfunção endotelial, reduzindo a produção de óxido nítrico (NO) e causando complicações para mãe e para o desenvolvimento fetal. O NO é principal regulador de eventos feto-placentários sendo produzido a partir da ação de 3 isoformas da óxido nítrico sintase (NOS). Polimorfismos de base única (SNPs) na NOS endotelial (eNOS) tem sido correlacionados à diversas patologias, sendo T-786C um dos SNPs responsáveis por reduzir a expressão da eNOS em 50%. Nosso estudo estabeleceu uma análise sobre estudo sobre o polimorfismo T-786C no gene da eNOS em mulheres no terceiro trimestre de gravidez, observando a possível associação com moléculas lipídicas e com a proteína c-reativa (PCR). Adicionalmente, a partir de ferramentas in silico, foram desenhados modelos de interação proteína-proteína (networks) para compreensão da importância do metabolismo da eNOS em condições normais e com patologias. Amostras de 92 mulheres grávidas foram submetidas à extração de DNA, identificação do polimorfismo T-786C por PCR-RFLP, e análise dos níveis de colesterol total (CT), HDL, LDL, triglicerídeos (TG) e PCR. Análise genotípica apresentou uma população de 71,73% TT, 26,08% CT e apenas 2,17% CC, estando o alelo C-786 presente em 15.21% do grupo estudado. Em relação à análise bioquímica, observou-se significância apenas para PCR quando as pacientes foram agrupadas por níveis sorológicos (normal ou alterado) de acordo com o genótipo da paciente. A CRP atua diretamente no desacoplamento da enzima eNOS prejudicando sua atividade e diminuindo a produção de NO, e servindo como marcador de eventos cardiovasculares. A partir das análises de bioinformática construímos duas networks. A primeira, denominada eNOSNet, possui 51 nós e 361 arestas de interação, mostrando proteínas ligantes da eNOS, pequenas moléculas e seus complexos formados. A segunda network, denominada eNOSNetD, relaciona proteínas envolvidas na via normal da eNOS com doenças descritas para o polimorfismo T-786C, tais como: doenças relacionadas ao sistema cardíaco, neurológico, à neoplasias e ao metabolismo lipídico, glicídico, protéico e hormonal. Estes dados podem ajudar na compreensão sobre a progressão de doenças que envolvem o funcionamento da eNOS e seus possíveis tratamentos e diagnósticos.

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Dissertations / Theses on the topic 'Nitrite metabolism'

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