Effects of green and nitrogen fertilization on the yield and yield components of irrigated winter beans / Adubação verde e nitrogenada sobre os componentes de produção e produtividade do feijoeiro de inverno irrigado

The contribution of plant residues to the soil is an essential requirement for the success of no-tillage systems, especially in areas with a tropical climate where the organic material decomposition rate is high. The type of straw present on the soil surface can influence the culture implanted subsequently, mainly with regard to the availability of nitrogen (N). The objective of this study was to investigate the effect of cultural remains of maize (exclusive or intercropped with cover crops) on the development and productivity of the common bean grown in succession and fertilized with different N doses. The experimental design was a randomized block arranged in a factorial scheme (5 × 4), with four replications. The treatments consisted of combinations of cultural remains of exclusive maize, maize + Crotalaria spectabilis, maize + Cajanus cajan, maize + Canavalia ensiformis, and maize + Urochloa ruziziensis cultivated previously and of four N rates (0, 40, 80, and 120 kg ha-1) applied to bean crops. The plots consisted of seven lines of 7.5 m length with 0.45 m spacing between the lines. The evaluated parameters were: dry matter of the plant cover, dry matter of the aerial part (beans), production components, weight of 100 grains, and grain yield. The intercropping of maize and cover crops promoted an increase in dry matter over the soil, compared to the exclusive maize crop. There was an increase in the dry matter of bean plants with the increase in N rates in the two years of cultivation; regarding productivity, there was an increment only in the first year of cultivation. The maize consortium with cover plants provided adequate soil cover, but did not influence the productivity of beans cultivated in succession in the two years of cultivation.(AU)

O aporte de resíduos vegetais ao solo é um dos requisitos essenciais para o sucesso do plantio direto, principalmente em áreas de clima tropical, cuja taxa de decomposição do material orgânico é elevada. O tipo de palha presente na superfície do solo pode influenciar a cultura implantada na sequência, principalmente ao que diz respeito à disponibilização de nitrogênio (N). Sendo assim, objetivou-se estudar o efeito dos restos culturais de milho (Zea mays L.) exclusivo ou consorciado com plantas de cobertura no desenvolvimento e produtividade do feijoeiro (Phaseolus vulgaris L.) cultivado em sucessão e adubado com doses de N. O delineamento experimental foi o de blocos casualizados disposto em esquema fatorial 5x4, com quatro repetições. Os tratamentos foram constituídos pela combinação do efeito dos restos culturais de milho exclusivo; milho + Crotalaria spectabilis; milho + Cajanus cajan; milho + Canavalia ensiformis; milho + Urochloa ruziziensis, cultivadas anteriormente e, por quatro doses de N aplicadas em cobertura na cultura do feijão (0, 40, 80 e 120 kg ha-1). As parcelas foram constituídas por 7 linhas de 7,5 m de comprimento com espaçamento de 0,45 m. Os parâmetros avaliados foram: matéria seca da cobertura vegetal, matéria seca da parte aérea (feijão), componentes de produção, massa de 100 grãos e produtividade de grãos. O consórcio entre milho e plantas de cobertura promoveu aumento da matéria seca sobre o solo, comparado ao cultivo de milho exclusivo. Houve incremento na matéria seca de plantas de feijão com as doses crescentes de N nos dois anos de cultivo e para a produtividade houve incremento somente no primeiro ano de cultivo. O consórcio do milho com plantas de cobertura proporcionou adequada cobertura do solo, porém não influenciou a produtividade do feijoeiro cultivado em sucessão nos dois anos de cultivo.(AU)

Nutrient enrichment effects on mycorrhizal fungi in an Andean tropical montane Forest.

Nitrogen (N) and phosphorus (P) deposition are increasing worldwide largely due to increased fertilizer use and fossil fuel combustion. Most work with N and P deposition in natural ecosystems has focused on temperate, highly industrialized, regions. Tropical regions are becoming more developed, releasing large amounts of these nutrients into the atmosphere. Nutrient enrichment in nutrient-poor systems such as tropical montane forest can represent a relatively large shift in nutrient availability, especially for sensitive microorganisms such as arbuscular mycorrhizal fungi (AMF). These symbiotic fungi are particularly critical, given their key role in ecosystem processes affecting plant community structure and function.To better understand the consequences of nutrient deposition in plant communities, a long-term nutrient addition experiment was set up in a tropical montane forest in the Andes of southern Ecuador. In this study, we investigated the impacts of 7 years of elevated N and P on AMF root colonization potential (AMF-RCP) through a greenhouse bait plant method in which we quantified root colonization. We also examined the relationship between AMF-RCP and rarefied tree diversity.After 7 years of nutrient addition, AMF-RCP was negatively correlated with soil P, positively correlated with soil N, and positively correlated with rarefied tree diversity. Our results show that AMF in this tropical montane forest are directly affected by soil N and P concentrations, but may also be indirectly impacted by shifts in rarefied tree diversity. Our research also highlights the need to fully understand the benefits and drawbacks of using different sampling methods (e.g., AMF-RCP versus direct root sampling) to robustly examine AMF-plant interactions in the future.

Oxandrolone use in adult burn patients. Systematic review and meta-analysis.

PURPOSE: This study is a systematic literature review and meta-analysis concerning the use of a testosterone synthetic analog, oxandrolone, and its use in severe adult burns. METHODS: Randomized prospective clinical studies, in English, Portuguese or Spanish, were sought on the following databases: MEDLINE, COCHRANE, EMBASE and LILACS. There was no restriction in relation to the publication date. RESULTS: This search produced 24 studies on MEDLINE and twelve articles were presented on the COCHRANE database .Sixteen were excluded due to the title not being related to this search or by including children. Of the eigth residual studies, after adaptation to the inclusion criteria, only four were selected. After analyzing the results, two were discarded since they did not present adequate patient characterization and the facts on these articles were analyzed differently from the others, hindering the meta-analysis. CONCLUSION: The analysis of the available data demonstrated significant benefits (p<0.05) considering lesser loss of corporal mass, lesser nitrogen loss, and shorter donor area healing time, when Oxandrolone was used, comparatively with the control group (placebo or not).

Oxandrolone use in adult burn patients. Systematic review and meta-analysis

PURPOSE: This study is a systematic literature review and meta-analysis concerning the use of a testosterone synthetic analog, oxandrolone, and its use in severe adult burns. METHODS: Randomized prospective clinical studies, in English, Portuguese or Spanish, were sought on the following databases: MEDLINE, COCHRANE, EMBASE and LILACS. There was no restriction in relation to the publication date. RESULTS: This search produced 24 studies on MEDLINE and twelve articles were presented on the COCHRANE database .Sixteen were excluded due to the title not being related to this search or by including children. Of the eigth residual studies, after adaptation to the inclusion criteria, only four were selected. After analyzing the results, two were discarded since they did not present adequate patient characterization and the facts on these articles were analyzed differently from the others, hindering the meta-analysis. CONCLUSION: The analysis of the available data demonstrated significant benefits (p<0.05) considering lesser loss of corporal mass, lesser nitrogen loss, and shorter donor area healing time, when Oxandrolone was used, comparatively with the control group (placebo or not). .

Gene networks for nitrogen sensing, signaling, and response in Arabidopsis thaliana.

Nitrogen (N) is an essential macronutrient for plants. In nature, N cycles between different inorganic and organic forms some of which can serve as nutrients for plants. The inorganic N forms nitrate and ammonium are the most important sources of N for plants. However, plants can also uptake and use organic N forms such as amino acids and urea. Besides their nutritional role, nitrate and other forms of N can also act as signals that regulate the expression of hundreds of genes causing modulation of plant metabolism, physiology, growth, and development. Although many genes and processes affected by changes in external or internal N have been identified, the molecular mechanisms involved in N sensing and signaling are still poorly understood. Classic reverse and forward genetics and more recently the advent of genomic and systems approaches have helped to characterize some of the components of the signaling pathways directing Arabidopsis responses to N. Here, we provide an update on recent advances to identify the components involved in N sensing and signaling in Arabidopsis and their importance for the plant response to N.

Identification of NH4+-regulated genes of Herbaspirillum seropedicae by random insertional mutagenesis.

Random mutagenesis using transposons with promoterless reporter genes has been widely used to examine differential gene expression patterns in bacteria. Using this approach, we have identified 26 genes of the endophytic nitrogen-fixing bacterium Herbaspirillum seropedicae regulated in response to ammonium content in the growth medium. These include nine genes involved in the transport of nitrogen compounds, such as the high-affinity ammonium transporter AmtB, and uptake systems for alternative nitrogen sources; nine genes coding for proteins responsible for restoring intracellular ammonium levels through enzymatic reactions, such as nitrogenase, amidase, and arginase; and a third group includes metabolic switch genes, coding for sensor kinases or transcription regulation factors, whose role in metabolism was previously unknown. Also, four genes identified were of unknown function. This paper describes their involvement in response to ammonium limitation. The results provide a preliminary profile of the metabolic response of Herbaspirillum seropedicae to ammonium stress.

Nutrient status and plant growth effects of forest soils in the Basin of Mexico.

The nutrient status of forest soils in the Mexico City Air Basin was evaluated by observing plant growth responses to fertilization with N, P or both nutrients combined. P deficiency was the most frequent condition for soil from two high pollution sites and N deficiency was greatest at a low N deposition site. Concentrations of Pb and Ni, and to a lesser extent Zn and Co, were higher at the high pollution sites. However, positive plant growth responses to P and sometimes to N, and results of wheat root elongation bioassays, suggest that heavy metal concentrations were not directly phytotoxic. Further studies are needed to determine if heavy metal toxicity to mycorrhizal symbionts of eucalyptus (Eucalyptus camaldulensis Dehnh.) from high pollution sites may explain the P deficiency and stunted growth. P deficiency is expected to limit the capacity for biotic N retention in N saturated forested watersheds in the Basin of Mexico dominated by Andisols.

Catabolismo muscular nos pacientes com infarto agudo do moicárdio / Muscular catabolism in patients with acute myocardial infarction

Introdução: O trauma e a sepse apresentam demanda metabólica aumentada devido à tríplice liberação hormonal com consequente aumento do catabolismo muscular. O infarto agudo do miocárdio(IAM) também pode ser considerado um trauma por apresentar as alterações hormonais características da fase aguda do estresse.Objetivo: Avaliar o grau de catabolismo muscular, quantificado pela excreção urinária de nitrogênio uréico em urina de 24 horas, nos pacientes admitidos com IAM.Métodos: Analisados prospectivamente 22 pacientes internados com IAM, sendo 12 de parede inferior e 10 de anterior, caracterizados elétrica e bioquimicamente com injúria e necrose transmural. A área do infarto foi diagnosticada pelo eletrocardiograma e confirmada pelas alterações no ecocardiograma. Foram excluídos os pacientes com insuficiência renal, IAM não transmural(ausência da onda Q evolutiva) e aqueles com mais de 48 horas de IAM. A coleta de urina de 24 horas foi realizada no 1º, 3º e 5º dias de internação para a quantificação da uréia excretada. O nitrogênio urinário foi calculado a partir da uréia, considerando-se um percentual nitrogendo de 46.66 por cento na molécula uréica. A avaliação estatística foi realizada pela análise de variância two way e pelo teste de Tukey, com nível de significância de 5 po cento.Resultados: O IAM, tanto anterior como inferior, apresenta catabolismo muscular evolutivo(terceiro dia) caracterizado como moderado(N2Dia3/Dia1, p igual 0,001). O catabolismo muscular foi idêntico mo IAM anterior e inferior (p igual 0,49). O catabolismo muscular é revertido no quinto dia.Conclusão: Os pacientes com IAM apresentaram um aumento reversível do catabolismo muscular

[Mechanisms for protecting nitrogenase from inactivation by oxygen]. / Mecanismos de protección de la nitrogenasa a la inactivación por oxígeno.

The biological fixation of dinitrogen is the most important way to access of N to organisms, this process requires a fairly high proportion of the ATP; which is generated in the course of respiratory electron transport reactions with O2 as electron acceptor. The Nitrogenase enzyme complex (the nitrogen. fixing enzyme) is sensitive to O2, that irreversible inactivates the enzyme. Diazotrophs must employ mechanisms which, on the other hand, permit the supply of O2 required for energy regeneration and protect Nase from the deleterious effect of O2. They have developed several strategies for limiting O2 access to Nase: 1).--It could avoid O2 and live in environments which are permanently anaerobic, 2).--Alternatively, it could generate a physical barrier around its Nase and in this way prevent O2 from diffusing to the enzyme, 3).--The microorganism could, by its metabolism, reduce the concentration of O2 within the vicinity of Nasa, 4).--They could modify its Nasa in such manner as to render it resistant to inactivation by O2 (conformational protection). 5).--Finally, the microorganism could simply balance Nasa inactivation with the synthesis of new enzyme. In this article we examine the antipathy between Nasa and O2, particularly with strict aerobic and photosynthetic microorganisms.

[Programmed cell death and apoptosis. The role of mitochondria]. / Muerte celular programada y apoptosis. Función de las mitocondrias.

Physiological cell death and apoptosis are natural processes genetically programmed, subjected to control by complex molecular mechanisms which elucidation is of particular interest for biology and medicine. Mitochondria play an essential role in physiological cell death and apoptosis. Apoptogenic effects develop in three phases, namely: (a) premitochondrial; (b) mitochondrial and (c) post-mitochondrial. During the first phase, apoptogenic signals (genotoxic agents, oxygen free radicals, corticoids, antibodies, etc.) interact with cell receptors activating specific mechanisms including thiol dependent proteases (caspases). As a consequence of those signals, mitochondrial damage results (membrane permeabilization, collapse of the membrane potential, swelling, membrane disruption, inhibition of electron transfer and oxidative phosphorylation). Other consequences of the mitochondrial disruption are the enhancement of free radical production and the exit of cytochrome c, caspases and endonucleases to the cytosol. During the third phase of apoptosis, free radicals and activated enzymes attack the cell protein structure and ADN, thus causing cell death. The mitochondrial regulation of apoptosis is controlled by the mitochondrial transitory permeability pore (MTPP) which is constituted by caspases, hexokinases, cytochrome c, ATP and ADP. MTPP is subjected to control by apoptogenic or antiapoptogenic agents which open or close it, according to their structure and the cell metabolic conditions. Uncontrolled opening of MTPP determines a massive exit of mitochondrial apoptogenic factors which in the cytosol and the nucleus exert their apoptogenic effects, thus producing cell death. MTPP can be modified by drugs with potential therapeutic actions thus opening interesting therapeutic possibilities. The role of apoptosis in pathologies such as degenerative diseases of the nervous system, autoimmunity diseases, SIDA and cancer is discussed.

Possible roles of nitric oxide and peroxynitrite in murine leishmaniasis

Activated macrophages simultaneously synthesize nitric oxide and superoxide anion which can react with each other producing peroxynitrite. Consequently, it has been difficult to assess the precise contribution of each of the formed reactive oxygen- and nitrogenderived species to the microbicidal activities of macrophages, particularly in vivo. To explore this problem, we are examining the formation and potential roles of nitrogen-derived intermediates in Leishmania amazonensis murine infection. Thus far, our results have demonstrated that peroxynitrite is a potent leishmanicidal agent in vitro and that both nitric oxide and peroxynitrite are formed during infection of susceptible BALB/c mouse strain. Nitric oxide was detected as the nitrosyl-hemoglobin complex by electron paramagnetic resonance analysis of blood drawn from mice at different times of infection, and it was shown to increase with the evolution of the disease. These results will be discussed in the context of the dual physiological role of nitric oxide either as a signaling molecule or as a deleterious agent.