>Magister Scientiae - MSc / Lignocellulose has a complex structure composed mainly of lignin, hemicellulose and cellulose. Several enzymes are needed for the degradation of lignocellulose into simple sugars. Actinomycetes are known to produce laecases which are able to degrade lignin. Laccase activities were detected in actinomycete strains MS26 isolated from soil collected from the Zambian Copperbelt and DFNR17 isolated from soil collected from a New Zealand farm. Morphological .studies showed that the strains produced extensively branched substrate mycelia and aerial hyphae. Micromorphological characteristics were consistent with the assignment of these strains to the genus Streptomyces. Isolates were found to be mesophiles, with growth occurring in a temperature range of 16 and 45°C. Optimal growth occurred at temperatures between 30 and 37°C. Analysis of the 16S rRNA gene sequences of the strains showed that strain MS26 had the highest sequence similarity (99%) to Streptomyces atrovirens strain NRRLB-16357 and Streptomyces viridodiastaticus strain IFO 13106. Strain DFNR17 had the highest 16S rRNA gene sequence similarity (99%) to Streptomyces althioticus strain KCTC9752. The strains shared several physiological and biochemical characteristics with their closest neighbours which, along with 16S rRNA gene sequences analysis, confirmed that the strains were members of the genus Streptomyces. Attempts to identify the laecase genes from these isolates by screening a fosmid library failed. Subsequently isolates were screened by PCR using laccase-like cooper oxidase degenerate primers designed from several Streptomyces strains. A 300 bp amplicon was obtained from both isolates. Phylogenetic analysis was performed and both amplicons from strains MS26 and DFNR17 had the highest similarities with the copper oxidase gene from Streptomyces griseoflavus strain Tu4000. Therefore it is probable that the laecase activity observed for these strains is due to the activity of copper oxidase gene products.

<p> A pedological investigation was made of the soil tongues in the Burford loam soils of S. W. Ontario. The purpose of the study was to determine the characteristic features of the soil tongues. The physical and chemical properties of a number of soil tongues were determined and one was used for a micromorphological investigation. Measurements of horizontal and vertical extent were also made. Discussion of the various hypotheses that might account for soil tongue development is included. Evidence for a periglacial climate is given and also f'or the existence of two distinct types of soil tongues. </p> / Thesis / Master of Science (MSc)

The relationship between soil properties and micromorphological features was studied in six Alfisol and six Spodosol profiles from Southern Ontario. The total porosity of the soil material was largely related to the size, shape and conformation of the soil voids in thin sections, while the differential development of plasma fabric could be used to discern a sequence of degrees of weathering which was also expressed by various mineralogical and physico-chemical indices. The relative proportions of soil constituents in thin sections was successfully used to indicate the existing textural discontinuities in five of the profiles studied. The elementary structure of soil thin sections is considered the most important micromorphological feature in the investigation of the degree of B horizon development in both Alfisol and Spodosol profiles. / Thesis / Doctor of Philosophy (PhD)

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Made available in DSpace on 2015-03-26T13:36:44Z (GMT). No. of bitstreams: 1 texto completo.pdf: 891731 bytes, checksum: f01a81cec277f616c4c03d6ff835d6ca (MD5) Previous issue date: 2013-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The toxicity of arsenic (As) and its effects on antioxidant system were analyzed in S. intermedia. Plants treated in nutrient solution, pH 6.5, were exposed to increasing concentrations of As over a period of 24 hours. The objectives of this study were to evaluate the effects of toxic levels of As on production of reactive oxygen species (ROS), the antioxidative system and root external morphology. The increasing concentration of As was accompanied by higher production of reactive oxygen species and lipid peroxidation. There was a linear augmentation in the amount of superoxide anion and an increase in amount of hydrogen peroxide up to a concentration of 1.0 mg L-1 As. Augmentation in the amount of anthocyanins and higher activity of the enzymes superoxide dismutase (SOD), peroxidase ( POX), ascorbato peroxidase (APX), glutathione peroxidase (GPX) and glutathione reductase (GR) was also observed. In contrast, there was a slight decay in catalase activity. Despite the reduction in the concentration of hydrogen peroxide in higher concentrations of As, the activity of antioxidant enzymes was not enough to buffer the damage, since the concentration of superoxide anion and MDA increased linearly with the increase of As. In a second experiment, nitric oxide (NO) was supplied as sodium nitroprusside (SNP). Plants treated in nutrient solution, pH 6.5, ½ ion force, were subjected to four conditions: control (nutrient solution); SNP (15 mg L-1); As (2.0 mg L-1); As + SNP (2.0 and 15 mg L-1, respectively) over a period of 24 hours. It was evaluated the influence of nitric oxide (NO) on membrane damage and activity of antioxidant enzymes and NO production enzyme. In situ fluorescence detection was used to reveal NO presence. There was an increase in MDA content, membrane leakage, activity of antioxidative enzymes and nitrate reductase comparing 2.0 mg L-1 As conditions with As + SNP treatment. Therefore, it is considered that the protective effect of the application of SNP appears reflects direct reaction of NO with ROS. The plants under arsenic stress showed higher NO production, confirmed by the increase in nitrate reductase activity and augmentation in fluorescence levels. When provided exogenously, NO also acted directly in the removal of toxic metabolites generated in response to As. Therefore, it was found that NO, supplied by SNP, buffers As toxicity in S. intermedia. / A toxicidade do arsênio (As) e seus efeitos no sistema antioxidante enzimático e não enzimático foram analisados em Spirodela intermedia. As plantas, cultivadas em solução nutritiva, pH 6,5, foram expostas a concentrações crescentes de As por 24 horas. Os objetivos deste estudo foram avaliar os efeitos de níveis tóxicos de As sobre a produção de espécies reativas de oxigênio (EROs), o sistema antioxidante enzimático e não enzimático e a morfologia externa das raízes. O acréscimo na concentração de As nas plantas desencadeou danos como aumento na produção de espécies reativas de oxigênio e peroxidação lipídica. Houve aumento linear do ânion superóxido, porém o peróxido de hidrogênio aumentou somente até a concentração de 1,0 mg L-1 de As. Também foi observado incremento no teor de antocianinas e na atividade das enzimas dismutase do superóxido (SOD), peroxidase (POX), peroxidase do ascorbato (APX), peroxidase da glutationa (GPX) e redutase da glutationa (GR). Em contraste, houve pequena queda na atividade da enzima catalase. Foi visualizado alterações micromorfológicas na coifa da raiz. Apesar da redução no teor de peróxido de hidrogênio nas concentrações mais elevadas, a atividade das enzimas antioxidantes não foi suficiente para amenizar os danos, uma vez que a concentração do ânion superóxido e de MDA aumentou linearmente com o acréscimo de As. As alterações micromorfológicas visualizadas na coifa da raiz, provavelmente foram decorrentes do aumento de EROs e consequente aumento da peroxidação lipídica. Em um segundo experimento, óxido nítrico (NO) foi suprido na forma de nitroprussiato de sódio (SNP). As plantas, cultivadas em solução nutritiva, pH 6,5, ½ força iônica, foram expostas a quatro tratamentos, sendo eles controle e As com e sem SNP, permanecendo nessas condições por 24 horas. Avaliou-se a influência do óxido nítrico (NO) sobre o dano de membrana e a atividade das enzimas antioxidativas e produtora de NO. Realizou-se também a detecção de fluorescência in situ desencadeada por NO. Houve aumento no teor de MDA, extravasamento de eletrólitos, enzimas antioxidativas e redutase do nitrato ao comparar o tratamento As (2,0 mg L-1) com As na presença de SNP. Sendo assim, considera-se que o efeito protetor da aplicação de SNP parece ser resultado da reação direta do NO com os EROs. Nas plantas submetidas ao estresse por As, observou-se maior produção de NO, resultado comprovado pela redutase do nitrato e pelo aumento na fluorescência. Quando fornecido na forma exógena, o NO também agiu diretamente na remoção de metabólitos tóxicos gerados em resposta ao As. Assim, verificou-se que o NO, fornecido pelo SNP, ameniza a toxicidade do As sobre o metabolismo de S. intermedia.

Submitted by Eunice Novais (enovais@uepg.br) on 2018-06-28T19:18:21Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Talita Rosas Ferreira.pdf: 3918159 bytes, checksum: 3af8401f079b1540a49f10a3f6fd3b2d (MD5) / Made available in DSpace on 2018-06-28T19:18:21Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Talita Rosas Ferreira.pdf: 3918159 bytes, checksum: 3af8401f079b1540a49f10a3f6fd3b2d (MD5) Previous issue date: 2018-04-23 / No presente estudo, foram investigados os efeitos da calagem superficial sobre: os atributos químicos, as propriedades de interação com a radiação e a estrutura (sistema poroso) de um Cambissolo Háplico alumínico. A estrutura do solo foi analisada em escala micrométrica, considerando monólitos (8×8×8 cm) e pequenos agregados do solo (2-4 e 1-2 mm de diâmetro). O experimento consistia de cinco faixas, uma delas em área de pasto, considerada como referência (REF) e representando as condições do solo antes da implementação do sistema de plantio direto (SPD), e as demais, sob SPD, receberam as seguintes doses de calcário: 0 (C0), 10 (C10), 15 (C15) e 20 (C20) t ha-1 aplicadas na superfície do solo. A coleta das amostras se deu aos trinta meses após o procedimento de calagem, nas camadas 0-10 cm (A) e 10-20 cm (B). Os atributos químicos do solo foram caracterizados de acordo com procedimentos experimentais padrões e a composição de óxidos do solo, obtida por meio de análise de espectroscopia de fluorescência de raios X (FRX), foi usada para o cálculo do coeficiente de atenuação de massa do solo (μm), por meio do código computacional XCOM, para as energias de ≈ 60 keV (241Am) e ≈ 662 keV (137Cs). Os valores de μm foram utilizados para calcular as demais propriedades de interação da radiação com o solo e para simular as variações causadas na densidade (D) e porosidade total (Pt) do solo. Para a análise da estrutura do solo, foram utilizadas imagens 3D de microtomografia computadorizada de raios X (μTC), com resolução espacial de 60 μm (monólitos), e de μTC utilizando radiação síncrotron (μTC-RS), com resolução espacial de 1,64 μm (agregados). A visualização, processamento e análise das imagens foram realizadas com o software Avizo Fire. Foram determinadas as seguintes propriedades micromorfológicas e geométricas: porosidade baseada na imagem (P’), número de poros (NP), distribuições de P’ e NP em função de intervalos de volume, comprimento, alongamento, formato, conectividade e tortuosidade dos poros (monólitos); e: P’, distribuições de P’ e NP em função de intervalos de volume, conectividade, tortuosidade e dimensão fractal (agregados). Complementarmente, a composição elementar dos agregados do solo foi avaliada por meio de medidas de FRX. Na maioria dos casos, os efeitos da calagem concentraram-se na camada A, onde houve melhora nos atributos químicos e, portanto, no grau de acidez do solo, bem como houve aumento nas propriedades de interação da radiação em função das doses de calcário. O aumento nas propriedades de interação da radiação foi mais acentuado para a energia de ≈ 60 keV em relação a ≈ 662 keV e, no primeiro caso, as mudanças causadas em μm promoveram variação considerável na D e Pt do solo, demonstrando a relevância do estudo. A exemplo dos efeitos da calagem sobre o sistema poroso de monólitos do solo, na camada A, ressalta-se o aumento de P’ e do número de poros em que o poro principal foi separado, os quais foram identificados como sendo mais alongados e mais conectados devido à calagem. A calagem promoveu ainda alterações no arranjo dos poros separados, em ambas as camadas, com a formação de poros cilíndricos na direção horizontal, o que pode ser atribuído ao estímulo da atividade da fauna do solo. Para os agregados de solo, na camada A, a porcentagem de cálcio foi elevada a um valor mais alto em agregados de 1-2 mm em comparação com aqueles de 2-4 mm, em função das doses de calcário. A calagem afetou negativamente a estrutura de pequenos agregados do solo, diminuindo a P’ e aumentando a tortuosidade de poros para agregados de 1-2 mm. Além disso, a calagem reduziu a dimensão fractal em agregados de ambas as classes de tamanhos, em acordo com o fato de que, com a calagem, poros maiores foram substituídos por poros menores em agregados de 1-2 mm, conforme análises de natureza quantitativa e qualitativa. / In the present study, effects of surface liming on: chemical attributes, soil-radiation interaction properties and the structure (porous system) of a Dystrudept soil were investigated. The soil structure was analyzed in micrometric scale, considering monoliths (8×8×8 cm) and tiny aggregates (2-4 and 1-2 mm in diameter). The trial consisted of five stripes, one of them under pasture, considered here as reference (REF), representing the soil conditions before the no-till system (NTS) implementation, and the remaining, under NTS, received the following lime rates: 0 (C0), 10 (C10), 15 (C15) and 20 (C20) t ha-1 on the soil surface. Samples were collected thirty months after the liming procedure, at the 0-10 cm (A) and 10-20 cm (B) soil layers. The soil chemical attributes were characterized according to standard experimental procedures and the soil oxide composition, obtained by X-ray fluorescence spectroscopy (XRF), was used for the calculation of the soil mass attenuation coefficient (μm), by means of the computer code XCOM, for the energies of ≈ 60 keV (241Am) amd ≈ 662 keV (137Cs). The μm values were used to calculate the remaining soil-radiation interaction properties and to simulate variations caused on soil density (D) and total porosity (Pt). For the soil structure analysis, 3D images of X-ray computed microtomography (μCT), with spatial resolution of 60 μm (monoliths), and 3D images of synchrotron radiation based X-ray computed microtomography (SR-μCT), with spatial resolution of 1,64 μm (aggregates) were used. The image visualization, processing and analysis were performed in the Avizo Fire software. The following micromorphological and geometrical properties were determined: image-based porosity (P’), number of pores (NP), distributions of P’ and NP as function of volume intervals, length, elongation, shape, connectivity, and tortuosity of pores (monoliths); and: P’, distributions of P’ and NP as function of volume intervals, connectivity, tortuosity, and fractal dimension (aggregates). Additionally, the elemental composition of the soil aggregates was evaluated by XRF. In the majority of cases, liming effects were concentrated at layer A, where there was an improvement of soil chemical attributes and, therefore, of soil acidity level, as well as there was an increase in the soil-radiation interaction properties as function of lime rates. The increase in soil-radiation interaction properties was more accentuated for the energy of ≈ 60 keV in relation to ≈ 662 keV and, in the former case, the μm variation promoted considerable variation in D and Pt, demonstrating the relevance of the study. Highlighted instances of liming effects on the porous system of the soil monoliths, at layer A, were an increase in P’ and in the number of pores into which the main soil pore was separated, which were identified as being longer and more connected due to liming. Moreover, liming promoted changes in the arrangement of the separated pores, at both soil layers, with the formation of cylindrical pores in the horizontal orientation, which can be attributed to stimulation of the soil fauna activity. Regarding the soil aggregates, at layer A, calcium was raised to a higher percentage in aggregates of 1-2 mm when compared to those of 2-4 mm, as function of the lime rates. Liming affected negatively the structure of the soil tiny aggregates, decreasing P’ and increasing the tortuosity of pores for 1-2 mm aggregates. Besides, liming decreased the fractal dimension in aggregates from both size classes, in accord to the fact that, with liming, larger pores were replaced by smaller ones in 1-2 mm aggregates, as both quantitatively and qualitatively analyzed.