"January 2003" / Includes bibliographical references (leaves 172-204) / xx, 204 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, 2003

<p>A large amount of non-protein nitrogen, in the form of urea and ammonium, is present in human breastmilk; however its physiological role in the infant is as yet not fully understood. It has been hypothesized that an insufficient enteric metabolism of urea could play a role in the sudden infant death syndrome (SIDS). This thesis was undertaken to study the enteric metabolism of non- protein nitrogen in healthy infants, in comparison with those who had succumbed to SIDS.</p><p>Aerobic and anaerobic faecal microflora, were studied in healthy infants from birth to 6 months of age. They were found to appear in faeces within 3 days of birth and were present throughout the first 6 months of life. The effect of nitrate, nitrite and nitric oxide on faecal urease activity was investigated and found to be inhibitory in action. The sigmoid faecal urease activity and sigmoid faecal urea content of SIDS infants were compared to those of control infants; significantly lower sigmoid faecal urease activity and greater sigmoid faecal urea content were found in the SIDS infants. The total number of SIDS cases occurring in Sweden during the period 1990 through 1996 was analysed regarding geographical and seasonal distribution, in relation to the nitrate concentration in drinking water and changes in the groundwater level. The northernmost parts of the country had its highest incidence when the rest of the country had its lowest incidence, and the occurrence of individual deaths was associated with the recharge of groundwater, which is known to increase its nitrate content. The effect of ingested ammonium on carbon dioxide production was determined in healthy infants using the doubly labelled water technique. No change in carbon dioxide production was observed.</p><p>An insufficient enteric metabolism of urea in infants and peak or greatly varying nitrate concentrations in drinking water are associated with the occurrence of SIDS. Ingested ammonium supplements in the given doses did not influence carbon dioxide production in healthy infants.</p>

A large amount of non-protein nitrogen, in the form of urea and ammonium, is present in human breastmilk; however its physiological role in the infant is as yet not fully understood. It has been hypothesized that an insufficient enteric metabolism of urea could play a role in the sudden infant death syndrome (SIDS). This thesis was undertaken to study the enteric metabolism of non- protein nitrogen in healthy infants, in comparison with those who had succumbed to SIDS. Aerobic and anaerobic faecal microflora, were studied in healthy infants from birth to 6 months of age. They were found to appear in faeces within 3 days of birth and were present throughout the first 6 months of life. The effect of nitrate, nitrite and nitric oxide on faecal urease activity was investigated and found to be inhibitory in action. The sigmoid faecal urease activity and sigmoid faecal urea content of SIDS infants were compared to those of control infants; significantly lower sigmoid faecal urease activity and greater sigmoid faecal urea content were found in the SIDS infants. The total number of SIDS cases occurring in Sweden during the period 1990 through 1996 was analysed regarding geographical and seasonal distribution, in relation to the nitrate concentration in drinking water and changes in the groundwater level. The northernmost parts of the country had its highest incidence when the rest of the country had its lowest incidence, and the occurrence of individual deaths was associated with the recharge of groundwater, which is known to increase its nitrate content. The effect of ingested ammonium on carbon dioxide production was determined in healthy infants using the doubly labelled water technique. No change in carbon dioxide production was observed. An insufficient enteric metabolism of urea in infants and peak or greatly varying nitrate concentrations in drinking water are associated with the occurrence of SIDS. Ingested ammonium supplements in the given doses did not influence carbon dioxide production in healthy infants.

Wheat production in the Pacific Northwest consists mainly of the soft white wheat market class. Over 80% of this wheat is exported. In recent years there has been an increase in soft white wheat production (due in a large part to improvements in the yielding capabilities of the genotypes grown in the Pacific Northwest). To expand into different commodity markets, it would be desirable to diversify and produce wheat cultivars representing more market classes and product uses. One opportunity would be to develop cultivars representing the Hard Red Winter market class. An effort to breed high yielding, high protein Hard Red Winter wheats is now underway at Oregon State University. This research was conducted to gain a better understanding of the components (genetic and/or environmental) that determine yield and grain protein content of hard red wheat genotypes. There were two general objectives of the research. One was to study the differences in nitrogen assimilation and remobilization in a diverse group of winter wheat genotypes grown in the different agricultural environments of Oregon. The second objective was to determine the efficacy of using "hill plots" (micro-plots) as a planting method to screen for agronomic and nitrogen assimilation traits in geneticly distinct genotypes which may be used as parents in breeding efforts. Results of this study indicate that genetic differences for nitrogen assimilation and remobilization do exist, and improvements in Pacific Northwest hard red wheat genotypes can be made with appropriate selection techniques. Data also indicate that the traditional high protein wheat genotypes (from the U.S. Great Plains) do not show an advantage from a grain protein concentration standpoint when produced in the Pacific Northwest. Additionally, the environment played a critical role in determining expression of harvest index, grain protein concentration, and nitrogen harvest index. Genotype by environment interactions were high, suggesting that zone-specific varieties may need to be developed in order to attain both high grain yields and high grain protein yields. / Graduation date: 1992

No description available.

The pathway of seawater ammonium assimilation and influence of light on amino acid synthesis remain unresolved in cnidarian symbioses. Labeled ammonium (10 μM 15NH4Cl) in seawater was used to trace the pathway of the incorporation into amino acids in host tissue, Zoanthus sp., and zooxanthellae, Symbiodinium microadriaticum. Freshly isolated zooxanthellae were exposed to 20 μM 15NH4Cl with coral homogenate to evaluate the role of host factors on amino acid synthesis. High performance liquid chromatography and mass spectrometry was used to measure percent labeling and concentrations of amino acids. In zooxanthellae, ammonium was assimilated into glutamine likely via glutamine synthetase and into glutamate via glutamine 2-oxoglutarate amidotransferase. Interrupting photosynthesis with DCMU did not inhibit glutamine and tryptophan synthesis however reduced the 15N-enrichment of glutamate, aspartate, and ornithine in zooxanthellae, as well as arginine, ornithine, and lysine in host tissue. Coral homogenate had little effect on the 15N-enrichment of glutamine, aspartate, and alanine in freshly isolated zooxanthellae. Evidence is presented to support the uptake of ammonium ions and data shows that glutamine and not glutamate is translocated to the coral host.

The commencement of in vitro differentiation is mediated by genetic changes that result in selective expression of genes and a shift in metabolism. The role of nitrate reductase, a key enzyme of nitrate assimilation, during differentiation was examined in this study using an in vitro Nicotiana tabacum (tobacco) callus culture system. In particular, the effects of nitrogen and light/dark regimes on callus differentiation and nitrate reductase were investigated. Methodology required for the analysis of nitrate reductase regulation during in vitro tobacco callus differentiation was established. Optimised in vivo, in situ and in vitro nitrate reductase assays yielded similar values and patterns during tobacco callus culture development, and the in vivo assay was selected for nitrate reductase activity measurement during subsequent experiments. Western blot analysis of tobacco callus acetone-extracted protein after sodium dodecyl sulfate-polyacrylamide gel electrophoresis using a spinach polyclonal nitrate reductase antibody yielded major bands at 71 and 48 kD, with numerous minor bands. Extraction of callus protein in the presence of various protectants did not prevent cleavage of putative nitrate reductase polypeptide. Slot blot detection of nitrate reductase mRNA using a [32p]- labelled nitrate reductase cDNA probe isolated from the plasmid pBMC102010 was not possible due to non-specific binding to nitrocellulose filters. Northern blotting of RNA fractionated by agarose gel electrophoresis using a [32p]-labelled nitrate reductase cDNA probe identified a single mRNA species at 3.5 kb, the expected size of tobacco nitrate reductase mRNA. In vitro tobacco callus differentiation on 60 or 120 mM nitrogen regimes and under light/dark (16/8 h), continuous dark or continuous light treatments were comparable in terms of fresh weight, protein and nitrate uptake. Higher levels of in vivo nitrate reductase activity were observed prior to visible shoot primordia in all treatments, suggesting that the developmental status of callus mediated the regulation of nitrate reductase. Putative nitrate reductase protein levels were not correlated with in vivo nitrate reductase activity during initial stages of tobacco callus differentiation under various light treatments; nitrate reductase mRNA levels could not be ascertained. These results suggested that post-translational control mechanisms were involved in nitrate reductase regulation during in vitro tobacco callus differentiation. / Thesis-(M.Sc.)-University of Natal, Durban, 1993.

Submitted by Luanna Matias (lua_matias@yahoo.com.br) on 2015-05-15T19:59:02Z No. of bitstreams: 2 Dissertação - Vanessa Rafaela Milhomem Cruz Leite - 2014.pdf: 2374224 bytes, checksum: bbdd09c7a011fbfa20239423f0d7f3fb (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luanna Matias (lua_matias@yahoo.com.br) on 2015-05-19T14:14:18Z (GMT) No. of bitstreams: 2 Dissertação - Vanessa Rafaela Milhomem Cruz Leite - 2014.pdf: 2374224 bytes, checksum: bbdd09c7a011fbfa20239423f0d7f3fb (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-05-19T14:14:18Z (GMT). No. of bitstreams: 2 Dissertação - Vanessa Rafaela Milhomem Cruz Leite - 2014.pdf: 2374224 bytes, checksum: bbdd09c7a011fbfa20239423f0d7f3fb (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-03-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The fungi of the genus Paracoccidioides sp are etiologic agents of disease paracoccidioidomycosis (PCM), are termodimórficos and have the ability to move the saprobiótica form to yeast form at a temperature around 37 ° C. The uptake is essential for the growth and adaptation of the fungus in host tissue, where nitrogen-dependent pathways have close relationship with pathogenicity. Pathogenic organisms possess a regulatory system called Nitrogen Catabolic Represion which is induced when nitrogen availability is limiting in surround causing the expression of genes necessary for nutrient uptake when preferred sources such as glutamine and ammonia are scarce. This regulatory process comprises a complex system in the infectious process. This study aims to identify proteins regulated by nitrogen depletion, where the pathogenic fungus Pb01-like was analyzed as a proteomic response. Pb01-like was grown in minimal medium control MMcM (+N) and treated MMcM (-N) for 6 hours at 37 ° C, cytoplasmic proteins were extracted and subjected to tryptic digestion and quantification. The proteomic profile revealed an expression of 135 proteins, 40 proteins induced or identified the treaty, 58 repressed or identified control and 44 proteins were expressed constitutively. In silico analyzes showed that the gene is regulated by formamidase areA transcription factor that responds conditions of nitrogen depletion in Aspergillus nidulans and the surrounding medium the enzymatic activity for the gene of formamidase Pb01-like induced depletion of nitrogen during. The amino acid sequence of the regulatory gene areA important in the metabolism of nitrogen was aligned between Pb01-like, Pb18, Aspergillus nidulans and Neurospora crasssa where this alignment showed high identity and homology of conserved zinc finger domains and DUF 1752. Metabolic pathways such as fermentation, gluconeogenesis, protein synthesis, nitrogen metabolism were induced for the depletion of nitrogen, showing a possible modulation of the metabolism of the fungus in order to be able to adapt to environments with nitrogen limitation. / Os fungos do genêro Paracoccidioides sp são agentes etiológicos da doença paracoccidioidomicose (PCM), são termodimórficos e possuem a capacidade de transitar da forma miceliana para a forma de levedura à temperatura em torno de 37°C. A captação de nitrogênio é essencial para o crescimento e adaptação do fungo em tecido hospedeiro, onde vias dependentes de nitrogênio possuem estreita relação com a patogenicidade. Organismos patogênicos possuem um sistema regulatório conhecido como Nitrogen Catabolic Repression que é induzido quando a disponibilidade de nitrogênio é limitante no meio, ocasionando a expressão de genes necessários para a captação do nutriente quando fontes preferenciais como a glutamina e amônia estão escassas. Esse processo regulatório compõe um complexo sistema no processo infeccioso. Este trabalho tem o objetivo de identificar proteínas reguladas pela depleção de nitrogênio, onde o fungo patogênico Pb01-like foi analisado quanto sua resposta proteômica. Pb01-like foi cultivado em meio mínimo controle MMcM (+N) e tratado MMcM (-N) por 6 horas a 37°C, as proteínas citoplasmáticas foram extraídas e submetidas a quantificação e digestão triptica. O perfil proteômico revelou uma expressão 135 proteínas, sendo 40 proteínas induzidas ou identificadas apenas no tratado, 58 proteínas reprimidas ou identificadas apenas no controle e 44 foram expressas constitutivamente. Análises in silíco revelou que o gene da formamidase é regulado pelo fator de transcrição areA, em Aspergillus nidulans que responde as condições de depleção de nitrogênio do meio circundante sendo a atividade enzimática para o gene da formamidase de Pb01-like induzida durante a depleção de nitrogênio. A sequência de aminoácidos do fator de transcrição areA importante regulador do metabolismo de nitrogênio foi alinhado entre Pb01-like, Pb18, Aspergillus nidulans e Neurospora crasssa onde esse alinhamento demonstrou uma alta identidade e homologia dos domínios conservados dedo de zinco e DUF 1752. Vias metabólicas como a fermentação, gliconeogênese, síntese de proteínas, metabolismo de nitrogênio estavam induzidas durante a depleção de nitrogênio, demonstrando uma possível modulação do metabolismo do fungo afim de conseguir adaptar-se a ambientes com limitação de nitrogênio.

Orientador: Ione Salgado / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-20T06:41:46Z (GMT). No. of bitstreams: 1 SantosFilho_PlinioRodriguesdos_D.pdf: 1637587 bytes, checksum: 89bdaa896ffa24aac0e2f5b00b8ece3a (MD5) Previous issue date: 2012 / Resumo: A nitrato redutase (NR) corresponde ao primeiro passo na assimilação do nitrato em plantas. Recentemente, essa enzima tem sido também relacionada à síntese de óxido nítrico (NO). Entre várias ações sinalizadoras para as plantas, o NO promove o acúmulo de fenilpropanóides pela ativação da expressão de enzimas iniciais dessa via. Contudo, uma correlação entre metabolismo de nitrogênio, emissão de NO e acúmulo de fenilpropanóides não foi estabelecida. Por isso, neste trabalho foi analisado o efeito do suprimento de nitrato e da deficiência na NR sobre a síntese de aminoácidos, a emissão de NO e o metabolismo de fenilpropanóides em diferentes tecidos de Arabidopis thaliana selvagem e mutante duplo deficiente para a NR (nia1 nia2). Análises cromatográficas mostraram que a mutante é deficiente na síntese de sinapoil malato (SM), fenilpropanóide predominante nas folhas, resultando no acúmulo de seu precursor sinapoil glicose (SG) e derivados de kaempferol. Essa deficiência não foi causada pela baixa assimilação do nitrato, já que a recuperação do conteúdo de aminoácidos na mutante não alterou seu perfil metabólico. Porém, a maior disponibilidade de nitrato aumentou a atividade da NR, a emissão de NO e os níveis de SM e diminuiu os níveis de SG, nos dois genótipos. O cultivo in vitro da mutante na presença de malato afetou a produção de SM de maneira dose-dependente, enquanto substâncias doadoras de NO causaram apenas um pequeno aumento em SG. Porém, a combinação malato/doador de NO promoveu a recuperação de SM ao nível da selvagem. Esse efeito sinergístico do NO com o malato também ocorreu quando as folhas da mutante foram infiltradas com esses compostos. Além disso, a atividade da enzima sinapoil glicose:malato sinapoil transferase (SMT) foi menor na mutante e a adição de NO aumentou a síntese de SM. Ainda, as folhas da mutante foram incapazes de acumular antocianinas sinapoiladas ao nível da selvagem quando submetidas a um estresse luminoso. Nos botões florais apenas derivados de kaempeferol e quercetina foram identificados e não houve diferença entre selvagem e mutante. Nas raízes não foram identificados fenilpropanóides, provavelmente porque esses compostos só são acumulados nesse órgão na presença de luz. Em relação ao acúmulo de aminoácidos, as folhas do mutante apresentaram níveis reduzidos de todos os aminoácidos parecendo atuar como fonte desses compostos para os botões florais, que não apresentaram nenhuma diferença em relação à selvagem. A glutamina recuperou os níveis de aminoácidos nas folhas, mas não causou diferença nos botões florais. Nas raízes, não houve diferença no conteúdo de aminoácidos entre selvagem e mutante, quando cultivadas no solo, mas in vitro, a mutante foi deficiente, provavelmente pela limitação de nutrientes nessa condição. Esses resultados indicam que o metabolismo dos ésteres de ácido sinápico nas folhas, controlado por aciltransferases dependentes de sinapoil glicose, está comprometido no mutante nia1 nia2 e sugere um potencial papel sinalizador para o NO na ativação dessas aciltransferases. Ainda, o efeito da deficiência na NR nos níveis de aminoácidos parece alterar as relações de fonte e dreno na planta e a folha foi o órgão mais afetado / Abstract: The nitrate reductase (NR) is the first step in nitrate assimilation in plants. Recently, this enzyme has also been related to the synthesis of nitric oxide (NO). Among various signaling actions for plants, NO promotes the accumulation of phenylpropanoids by activating the expression of the initial enzymes of this pathway. However, a correlation between nitrogen metabolism, NO emission and accumulation of phenylpropanoids has not been established. Therefore, this work analyzed the effect of nitrate supply and NR deficiency on the synthesis of amino acids, emission of NO and phenylpropanoid metabolism in different tissues of wild type and NR double-deficient (nia1 nia2) Arabidopsis thaliana plants. Chromatographic analysis showed that the mutant is deficient in the synthesis of sinapoylmalate (SM), the major phenylpropanoid in the leaves, resulting in accumulation of its precursor sinapoylglucose (SG) and kaempferol derivatives. This deficiency was not caused by the low nitrate assimilation, since the recovery of the amino acid content in the mutant did not change its metabolic profile. In contrast, an increased supply of nitrate enhanced NR activity and NO production, and increased SM and decreased SG levels in both genotypes. The in vitro cultivation of mutant in the presence of malate affected the production of SM in a dose-dependent manner, whereas NO donors caused only a slight increase in SG. However, the combination of malate/NO donor promoted the recovery of SM at the level of wild type plants. The synergistic effect of NO with malate in the recovery of SM also occurred when the mutant leaves were infiltrated with these compounds. Furthermore, sinapoylglucose:malate sinapoyltransferase (SMT) activity was reduced in the mutant, and the addition of NO increased SM synthesis. Additionally, mutant leaves were unable to accumulate sinapoylated anthocyanins at the level of wild type when exposed to light stress. In the flower buds just kaempeferol and quercetin derivatives were identified and there was no difference between wild type and mutant. In the roots, phenylpropanoids were not identified, probably because these compounds are accumulated in this organ only in the presence of light. Regarding the accumulation of amino acids, the mutant leaves showed reduced levels of all amino acids and appeared to act as a source of these compounds to the flower buds that showed no difference from the wild plant. Glutamine recovered the amino acid levels in leaves, but caused no difference in flower buds. In the roots, there was no difference in the amino acid content between wild type and mutant, when grown in soil, but in vitro, the mutant was deficient, probably due to nutrient limitation in this condition. These results indicate that hydroxycinnamate ester metabolism in leaves, controlled by the sinapoylglucose-dependent sinapoyltransferases, is compromised in nia1 nia2 mutant and suggests a potential signaling role for NO in the activation of these acyltransferases. Additionally, the effect of NR deficiency in the levels of amino acids appears to alter the relationship of source and sink in the plant and the leaf is the most affected organ / Doutorado / Bioquimica / Mestre em Biologia Funcional e Molecular

The influence of iron nutrition on patterns of photosynthetic behavior, nitrogen metabolism, and fixed-carbon allocation is reported for a common freshwater green alga. Cultures of Scenedesmus quadricauda were grown in Fraquil medium in which iron concentrations ranged from 1.0 μM to 0.01 μM (log 10-6 to 10-8 M, respectively). Carbon 14 and nitrogen uptake experiments were conducted at photosynthetically saturating and subsaturating photon flux densities.