Bacterial diversity in soil in response to different plans, phosphate fertilizers and liming

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effectiveness of fused magnesium potassium phosphate for marandu grass

O alto custo atual do KCl e a grande dependência de sua importação para suprir a demanda nacional sugerem a necessidade de estudos que procurem avaliar a eficiência de outras fontes de K, principalmente aquelas baseadas em matéria-prima nacional. Nesse sentido, foi conduzido um experimento em casa de vegetação com amostras de um Latossolo Vermelho distrófico textura média, adotando-se o delineamento inteiramente casualizado em esquema fatorial 4 x 3 x 2, sendo quatro doses de K (0, 60, 120 e 180 mg kg-1 de K), três fontes [(cloreto de potássio (KCl)], termofosfato magnesiano potássico (FMPP) e a mistura de 70 % FMPP + 30 % KCl) e duas granulometrias (100 e 60 mesh), com três repetições. Verificou-se que a adubação potássica promoveu incrementos significativos na produção de matéria seca (parte aérea) e nos teores de K no solo e na planta, não havendo diferenças entre as fontes e suas granulometrias. Os níveis críticos de K no solo e na parte aérea das plantas foram de 1,53 mmol c dm-3 e 19,1 g kg-1, respectivamente.

Carbohydrate metabolism of Xylella fastidiosa: Detection of glycolytic and pentose phosphate pathway enzymes and cloning and expression of the enolase gene

The objective of this work was to assess the functionality of the glycolytic pathways in the bacterium Xylella fastidiosa. To this effect, the enzymes phosphoglucose isomerase, aldolase, glyceraldehyde-3-phosphate dehydrogenase and pyruvate kinase of the glycolytic pathway, and glucose 6-phosphate dehydrogenase of the Entner-Doudoroff pathway were studied, followed by cloning and expression studies of the enolase gene and determination of its activity. These studies showed that X. fastidiosa does not use the glycolytic pathway to metabolize carbohydrates, which explains the increased duplication time of this phytopatogen. Recombinant enolase was expressed as inclusion bodies and solubilized with urea (most efficient extractor), Triton X-100, and TCA. Enolase extracted from X. fastidiosa and from chicken muscle and liver is irreversibly inactivated by urea. The purification of enolase was partial and resulted in a low yield. No enzymatic activity was detected for either recombinant and native enolases, aldolase, and glyceraldehyde-3-phosphate dehydrogenase, suggesting that X. fastidiosa uses the Entner-Doudoroff pathway to produce pyruvate. Evidence is presented supporting the idea that the regulation of genes and the presence of isoforms with regulation patterns might make it difficult to understand the metabolism of carbohydrates in X. fastidiosa.

Phosphate fertilization and phosphorus forms in an Oxisol under no-till

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fission-track dating of South American natural glasses: an overview

Although many glass-bearing horizons can be found in South American volcanic complexes or sedimentary series, only a relatively few tephra and obsidian-bearing volcanic fields have been studied using the fission-track (FT) dating method. Among them, the volcanics located in the Sierra de Guamani (east of Quito, Ecuador) were studied by several authors. Based upon their ages, obsidians group into three clusters: (1) very young obsidians, similar to 0.2Ma old, (2) intermediate-age obsidians, similar to 0.4- similar to 0.8 Ma old, and (3) older obsidians, similar to 1.4- similar to 1.6 Ma old. The FT method is also an efficient alternative technique for identification of the sources of prehistoric obsidian artefacts. Provenance studies carried out in South America have shown that the Sierra de Guamani obsidian occurrences were important sources of raw material for toot making during pre-Columbian times. Glasses originated from these sources were identified in sites distributed over relatively wide areas of Ecuador and Colombia.Only a few systematic studies on obsidians in other sectors were carried out. Nevertheless, very singular glasses have been recognised in South America, such as Macusanite (Peru) and obsidian Quiron (Argentina), which are being proposed as additional reference materials for FT dating. Analyses of tephra beds interstratified with sedimentary deposits revealed the performance of FT dating in tephrochronological studies. A remarkable example is the famous deposit outcropping at Farola Monte Hermoso, near Bahia Blanca (Buenos Aires Province), described for the first time by the middle of the 19th century by Charles Darwin.Considering the large number of volcanic glasses that were recognised in volcanic complexes and in sedimentary series, South America is a very promising region for the application of FT dating. The examples given above show that this technique may yield important results in different disciplinary fields. (c) 2005 Elsevier Ltd. All rights reserved.

Fission-track dating of Macusanite glasses with plateau and size correction methods

Two Macusanite pebbles (MB1 and MB2) were dated with the fission-track method. Six irradiations were carried out in different nuclear reactors: Pavia (Italy), IPEN-CNEN (Brazil) and IPEN-Lima (Peru). Measurements of the thorium and uranium induced-fission per target nucleus using natural thorium thin films and natural U-doped glasses calibrated against natural uranium thin films, together with lambda(F) of 8.46 x 10(-17) a(-1) were used to determine the ages. The apparent ages were corrected using the plateau and size correction methods. Track measurements were performed by different analysts, using different counting criteria. In addition, tracks were measured on samples which had been submitted to thermal treatment as well as on samples which had not been heated. Thermal treatments were carried out to erase the fossil tracks before neutron irradiation. No significant differences have been found in individual results, using the two Macusanite pebbles and the different nuclear reactors, age correction techniques, analysts, track-counting criteria, and thermal treatments before neutron irradiation. The great majority of the results (14/17) is compatible with the Ar-Ar ages of 5.12 +/- 0.11 and 5.10 +/- 0.11 Ma, Macusanite MB1 and MB2, respectively. However, the fission-track ages are systematically less (similar to8%) than the Ar-Ar ages of the two Macusanite samples studied. (C) 2003 Published by Elsevier Ltd.

New constraints on ages of glasses proposed as reference materials for fission-track dating

New analyses have been performed in order to enhance the data-set on the independent ages of four glasses that have been proposed as reference materials for fission-track dating. The results are as follows. Moldavite - repeated (40)Ar/(39)Ar age determinations on samples from deposits from Bohemia and Moravia yielded an average of 14.34 +/- 0.08 Ma. This datum agrees with other recent determinations and is significantly younger than the (40)Ar/(39)Ar age of 15.21 +/- 0.15 Ma determined in the early 1980s. Macusanite (Peru) -four K-Ar ages ranging from 5.44 +/- 0.06 to 5.72 +/- 0.12 Ma have been published previously. New (40)Ar/(39)Ar ages gave an average of 5.12 +/- 0.04 Ma. Plateau fission-track ages determined using the IRMM-540 certified glass and U and Th thin films for neutron fluence measurements agree better with these new (40)Ar/(39)Ar ages than the previously published ages. Roccastrada glass (Italy) - a new (40)Ar/(39)Ar age, 2.45 +/- 0.04 Ma, is consistent with previous determinations. The Quiron obsidian (Argentina) is a recently discovered glass that has been proposed as an additional reference material for its high spontaneous track density (around 100 000 cm(-2)). Defects that might produce spurious tracks are virtually absent. An independent (40)Ar/(39)Ar age of 8.77 +/- 0.09 Ma was determined and is recommended for this glass. We believe that these materials, which will be distributed upon request to fission-track groups, will be very useful for testing system calibrations and experimental procedures.

A GC-FID Method to Determine Styrene in Polystyrene Glasses

The styrene levels of polystyrene (PS) glasses from the most consumed brands of disposable glasses intended for water and coffee in Brazil were determined. A GC-FID method was developed and validated, showing good precision and accuracy. The method was successfully used to determine styrene in 11 PS glass brands. The styrene levels ranged from 1.68 to 43.69 mg/100 g glass, depending on the kind of polymer, thickness, and glass brand. It could be used to control the content of styrene in the polymer. The migration of styrene from the glasses into water and 20 % ethanol was not detected.

Recombinant expression of glycerol-3-phosphate dehydrogenase using the Pichia pastoris system

In the present study, the GPD2 gene from Saccharomyces cerevisiae, which codifies for the enzyme glycerol-3-phosphate dehydrogenase (GPDH), was cloned from the pPICZ-alpha expression vector and used with the purpose of inducing the extracellular expression of the glycerol-3-phosphate dehydrogenase under the control of the methanol-regulated AOX promoter. The presence of the GPD2 insert was confirmed by PCR analysis. Pichia pastoris X-33 (Mut(+)) was transformed with linearized plasmids by electroporation and transformants were selected on YPDS plates containing 100 mu g/mL of zeocin. Several clones were selected and the functionality of this enzyme obtained in a culture medium was assayed. Among the mutants tested, one exhibited 3.1 x 10(-2) U/mg of maximal activity. Maximal enzyme activity was achieved at 6 days of growth. Medium composition and pre-induction osmotic stress influenced protein production. Pre-induction osmotic stress (culturing cells in medium with either 0.35 M sodium chloride or 1.0 M sorbitol for 4h prior to induction) led to an increase in cell growth with sorbitol and resulted in a significant increase in GPDH productivity with sodium chloride in 24h of induction approximately fivefold greater than under standard conditions (without pre-induction). (C) 2010 Elsevier B.V. All rights reserved.

Phosphate forms in plant and their internal buffering in five soybean cultivars

Diferenças inter e intra-específicas na habilidade de suportar períodos de estresse nutricional podem dever-se à capacidade de armazenar e liberar íons dos vacúolos, e, ou, à intensidade de retranslocação de nutrientes em tais condições. Neste trabalho, pretendeu-se avaliar diferenças varietais quanto ao tamanho do pool não-metabólico de Pi; velocidade de liberação do Pi previamente armazenado (VLPi), quando o P citoplasmático cai a um valor limite; capacidade de transportar Pi de regiões menos ativas para aquelas mais ativas metabolicamente e definir compartimentos que são preferencialmente fontes e os que são preferencialmente drenos para o Pi, em condições de absorção limitada de P. Avaliaram-se a produção de matéria seca e os teores internos de Pi, orgânico (Po) e total solúvel em ácido (Pts), de diferentes órgãos de plantas dos cultivares de soja (Glycine max L. Merrill) Santa Rosa, Uberaba, IAC8, Doko e UFV1, submetidos a oito dias de omissão do elemento. A VLPi foi estimada como tangente às equações obtidas para Pi como função do perído de omissão no ponto médio do período de omissão em que houve maior decréscimo em Pi (zero a quatro dias de omissão de P), t = dois dias, considerando-se que -deltaPi/deltat expressa a velocidade de liberação de Pi. A capacidade interna de tamponamento de Pi (CTIPi) foi calculada como o inverso da VLPi. O cultivar Santa Rosa apresentou maior capacidade de armazenar Pi, quando o suprimento externo foi alto, liberando-o mais intensamente sob condições de baixo suprimento de P que os cultivares IAC8 e UFV1. O cultivar Uberaba mostrou-se superior ao Doko em sua habilidade de armazenar e utilizar o Pi. Folhas superiores mostraram ser o principal dreno para o Pi armazenado em folhas medianas e inferiores, seguidas por raízes e caules. Raízes comportaram-se como fontes ou drenos para o Pi. Raízes e folhas superiores apresentaram maiores (VLPi) e menores valores de CTIPi que folhas medianas e folhas inferiores, sendo o caule o compartimento com menor VLPi e maior CTIPi. Dentre as variedades, as diferenças foram pequenas, destacando-se a maior VLPi e menor CTIPi do cultivar Santa Rosa. O cultivar Doko apresentou a menor VLPi e maior CTIPi, enquanto Uberaba, IAC8 e UFV1 ocuparam posição intermediária quanto a essas características.

Thermo and photochromic properties of Na2O-WO3-SbPO4 glasses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Growth of Calcium Phosphate Using Chemically Treated Titanium Oxide Nanotubes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

PREPARATION and CHARACTERIZATION of CELLULOSE/HYDROUS NIOBIUM PHOSPHATE HYBRID

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Quantitative microscopy characterization of hydrous niobium phosphate into bleached cellulose

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

DSC studies on crystallization mechanisms of tellurite glasses

The purpose of this work is to study the 20Li(2)O-80TeO(2) glass using the differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques in order to understand the crystallization kinetics on this glass matrix. To study the glass by DSC, screened samples with different particle sizes to resolve the observed asymmetrical crystallization peak were used. DSC curves for particles smaller than 38 mum in size show two distinct crystallization peaks, associated to distinct phase transformation in this glass, leading to activation energies at 301 and 488 kJ mol(-1). XRD analysis reveals that the first crystallization peak is attributed to TeO2 crystalline phase while the second one to the alpha-TeO3 and an unidentified phase.(C) 2004 Elsevier B.V. All rights reserved.