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Morpho logical, anatomical, and histochemical effects of S-ethyl dipropylthiocarbamate (EPTC) on Avena sativa var . overland were studied after treatment of seeds at various EPTC concentrations. The oat seed germination percentage was not affected by EPTC treatment. EPTC delayed initial root and coleoptile development at all concentrations used . Two or three days after treatment, however, the roots of seedlings treated with EPTC concentrations lower than 3 ppm grew at the same rate as the untreated seedlings and showed no abnormalities. Primary and adventitious root growth of seedlings treated with 3 ppm and higher was inhibited. Most of the adventitious roots remained in the radicle stage and failed to elongate. Bases of the roots became necrotic and were quite brittle . Formative effects were greater in the shoot than in the root. As result of treatment, coleoptiles became chlorotic, thickened, and were hard and brittle . The first true leaf of treated seedlings tended to adhere to the coleoptile and was broken as the coleoptile elongated . The complete shoot meristem of 12 ppm EPTC treated seedlings broke at the base . Young leaves formed within coleoptiles of treated seedlings oftain failed to emerge. His tochemica l studies s howed more carbohydrates in the coleoptiles of the EPTC treated oat seedlings than in those of the untreated seedlings . The lip1d-containing materials in the coleoptiles of the germinating oat seedlings disappeared from the coleoptiles of fully grm;n untreated oat seedlings , while they still persisted in the coleoptiles of 5-day-old EPTC treated oat seedlings. This suggests that EPTC might inhibit the breakdown and utili zation of stored foods .

Made available in DSpace on 2016-06-02T19:32:02Z (GMT). No. of bitstreams: 1 4290.pdf: 2504541 bytes, checksum: f44f9691df69aedba30bdbb41b8c7ba7 (MD5) Previous issue date: 2012-02-29 / Financiadora de Estudos e Projetos / Changes in river basins such as the deforestation of riparian vegetation, the expansion of agricultural activities and construction of dams, are examples of anthropogenic interference, which interferes with the diversity of aquatic insects in streams and rivers. This study aimed to investigate the distribution patterns of communities of aquatic insects in a longitudinal profile of the Ribeirão Anhumas, discontinued by the construction of five impoundments and the influence of different land uses. Sampling occurred in the river basin of the Ribeirão Anhumas in an area upstream and downstream of the five dams, on the towards headstream/mouth of the creek. We analyzed the concentration of potentially bioavailable metals (Fe, Mg, Mn, Cu, Zn, Ni, Cd and Cr) in sediment. For the sampling effort fauna, the quick sampler method was used for a period of two minutes. Specimens were identified to lowest possible taxonomic level and classified by feeding groups. The highest concentrations of metals in the sediment were recorded in parts of the dam 4 (R4), which is observed around sugar cane farming, the analysis indicated contamination by Ni. 2498 aquatic insects were identified, wich distributed in 92 genera. Polypedilum (Chironomidae, Diptera) was the taxon more representative of the community, as well as the guilds of the predators and gathering-colectors. The stretches with preserved riparian vegetation had the highest values of richness, taxonomic diversity and water quality score. The Student statistical test indicated that there were no significant differences in the abundance and richness between the streches. Diversity indices showed a decrease in diversity between the upstream and downstream sections, and longitudinal profile. We concluded that the basin of the Ribeirão Anhumas is well preserved, where there was no interference from lotic habitat discontinuity of the dams, as well as different land uses low-impact exercise on aquatic insect community. / Alterações em bacias hidrográficas, como o desmatamento da vegetação ripária, a expansão das atividades agrícolas e a construção de represas, são exemplos das interferências antrópicas, que interferem na diversidade de insetos aquáticos nos córregos e rios. O presente estudo teve como objetivo investigar padrões de distribuição de comunidades de insetos aquáticos em um perfil longitudinal do Ribeirão das Anhumas, descontinuado pela construção de cinco represamentos e pela influência de diferentes usos da terra. As coletas ocorreram na bacia hidrográfica do Ribeirão das Anhumas, a montante e a jusante de cinco represamentos, no sentido nascente/foz do ribeirão. Foram analisadas concentração de metais potencialmente biodisponíveis (Fe, Mg, Mn, Cu, Zn, Ni, Cd e Cr) no sedimento. A fauna foi coletada pelo método de varredura, por um período de dois minutos. Os exemplares foram identificados até o menor nível taxonômico possível e classificados por grupos funcionais. As maiores concentrações de metais no sedimento, foram registrados nos trechos da represa 4 (R4), cujo entorno observa-se atividade agrícola canavieira, as análises indicaram contaminação por Ni. Foram identificados 2.498 insetos aquáticos, distribuídos em 92 gêneros. Polypedilum (Chironomidae, Diptera) foi o táxon mais representativo da comunidade, e entre as guildas predominaram os predadores e coletores-juntadores. Nos trechos com vegetação ripária preservada verificaram-se os maiores valores de riqueza, diversidade taxonômica e do escore de qualidade da água. O teste estatístico de Student indicou que não houve diferenças significantes na abundância e riqueza entre os trechos analisados. Os índices de diversidade demonstraram um decréscimo da diversidade entre os trechos a montante e jusante, e no perfil longitudinal. Conclui-se que a bacia hidrográfica do Ribeirão das Anhumas está bem conservada, aonde não houve interferência da descontinuidade de habitat lótico das represas, bem como os diferentes usos da terra exercem baixo impacto sobre a comunidade de insetos aquáticos.

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Natural products represent an incredibly diverse set of chemical structures and activities. Given this fathomless, ever-evolving diversity, a reasonable approach to designing new molecules entails taking a closer look at the biochemistry that Nature has crafted over billions of years on Earth. In particular, much can be learned by unveiling the architectures of proteins, life’s molecular machines, through methods like X-ray crystallography. Acquiring the blueprints of an enzyme brings us closer to understanding the mechanism by which the enzyme transforms a simple substrate it into a complex product with biological function, and inspires us to engineer such systems to our own ends. With a focus on macromolecular structural characterization, this document elaborates on five Gram-negative bacterial biosynthetic enzymes from two categories: Cell-surface modifiers and polyketide synthases. Among the first category are the glycyl carrier protein AlmF and its ligase AlmE of Vibrio cholerae and the phosphoethanolamine transferase EptC of Campylobacter jejuni. These proteins are responsible for decorating cell-surface molecules (e.g., lipid A) of pathogenic bacteria with small functional groups to promote antibiotic resistance, motility, and host colonization. AlmE and EptC represent potential drug targets and their structures lay the groundwork for the design of therapeutics against food-borne illnesses. Included in the second category are the [4+2]-cyclase SpnF and two ketoreductase-linked dimerization elements, each from the spinosyn biosynthetic pathway in Saccharopolyspora spinosa. The former catalyzes a putative Diels-Alder reaction to form a tricyclic precursor of the insecticide spinosad, while the latter two organize ketoreductase domains within modules of a polyketide synthase. The second category also includes Ralstonia eutropha β-ketoacyl thiolase B, a substrate-permissive enzyme that can make or break carbon-carbon bonds with assistance from Coenzyme A or an analogous thiol. Each of these proteins exhibit intriguing structural features or catalyze reactions that show promise for biochemical engineering. / text