321 resultados para Estrutura celular


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The cell wall is a rigid structure essential for the survival of fungi. A knowledge of its composition is therefore useful for the development of novel anti-fungal drugs. In this context, polysaccharides as main components of the fungal cell wall have been the subject of intense scientific study over the years. The information gained from the knowledge of the structure of these macrobiomolecules could therefore be valuable in elucidating the mechanisms of their biosynthesis in the cell walls of pathogenic fungi infecting plants and animals alike. Determination of the chemical structures of these polysaccharides (endo) is preceded by their extraction and purification. The extractions, generally lead to neutral and/ or alkaline soluble biopolymers in groups according to their solubilities. Mixtures of polysaccharides in these extracts can then be purified by a combination of chemical and chromatographic methods. Following purification, the polysaccharides, considered homogeneous, can be characterized structurally using conventional techniques of carbohydrate chemistry, such as hydrolysis, methylation analysis, and FT-IR, 13C- and 1H- NMR spectroscopy. This review surveys the main scientific literature that characterizes polysaccharides constituting the fungal cell wall.

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Type-1 diabetes patients suffer from frequent episodes of acidosis caused by an increased fatty acid metabolism and consequently increased plasma level of acetoacetate (AcAc) and β-hydroxybutyrate (β-HOB). This article describes a study of the effects of pathological concentrations of AcAc and β-HOB on lipoperoxidation, cell viability and the release of the CXCL8 (IL-8) cytokine by activated neutrophils. Neutrophils from healthy donors were isolated by density gradient (Histopaque® 1077/1119) and incubated with the ketone bodies. Lipoperoxidation was determined as thiobarbituric acid reactive substances (TBARS). The cell viability was evaluated by the release of intracellular lactate dehydrogenase. The release of CXCL8 was measured by ELISA in a 24-h culture of opsonized zymosan-stimulated neutrophils. AcAc, but not β-HOB, provoked a dose-dependent increase in the neutrophil membrane lipoperoxidation (p<0.05; r =0.9915). In the cytotoxicity assay, a dose-dependent release of LDH was observed when the neutrophils were incubated with AcAc in concentrations up to 40 mM (p<0.05). β-HOB was devoid of effect. The release of CXCL8 was inhibited by AcAc and β-HOB in a dose-dependent manner. In conclusion, these results suggest that the accumulation of ketone bodies in diabetic patients could be involved in their usually increased susceptibility to infection.

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The objective of this work was to make a comparative analysis of germ cell organization at different stages of cellular differentiation in adult males of Dendropsophus nanus (Boulenger, 1889), Pseudis limellum (Cope, 1862), P. paradoxa (Linnaeus, 1758), and Scinax acuminatus (Cope, 1862), belonging to the family Hylidae; and Leptodactylus chaquensis (Cei, 1950) and L. podicipinus (Cope, 1862), belonging to the family Leptodactylidae, collected in the Pantanal and in Serra da Bodoquena, Mato Grosso do Sul State, Brazil. The testes were removed and fixed, dehydrated in a graded series of ethanol and embedded in methacrylate glycol resin (Historesin Leica®). The sections were stained by 1% toluidine blue and observed under light microscope. It was detected that all individual of the Hylidae family show, throughout the year, the presence of all germ cell types of spermatogenesis. However, all Leptodactylidae family individuals only show the presence of all germ cell types during the rainy season. The variations of characteristics in seminiferous epithelium organization, as well as the evident difference in the amount of spermatozoa inside the tubules, are evidence that the anurans in this work show different forms of spermatogenesis development throughout the year: the cycle is continuous for the Hylidae family, and discontinuous with explosive release of spermatozoa for the Leptodactylidae family.

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This study aims to examine the thermal structure of the urban climate based on the interpretation of the satellite Landsat 7 (thermal channel) and measures for the area. It identifies how the production of urban climate develops based on an analysis of the structure of space forms and characteristics of land use and constructive materials in the generation of heat islands and their implications in environmental comfort in a tropical climate medium size city at Brazil. To check intra-urban air temperature, measures were carried out in mobile transects in the North-South and East-West routes. Thermal Channel data of Landsat-7, were converted to surface values. The results showed that the pattern of urbanization and characteristics of land use are responsible for the distribution of temperature generating heat islands in downtown and popular densely built neighborhoods. In those cases the highest indexes of social segregation added to higher temperature also provokes elevation in the number of illnesses and morbidity cases, mostly of respiratory diseases.

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This experiment was performed aiming to evaluate tiller population density, forage mass and its morphological components on pastures of Brachiaria decumbens cv. Basilisk. during deferment. The treatments encompassed four deferred grazing periods (18, 46, 74 and 121 days). A randomized block design with two replications was used. The numbers of vegetative tillers (VT), reproductive tillers (RT) and dead tillers (DT) in the pasture were determined. The masses of green leaf blade (GLBM), dead stem (DSM) and dead forage (DFM) were also determined. There was a reduction in the number of VT (from 1, 491 to 944 tiller m-2) during the deferment period. RT and DT numbers were not influenced by the deferment periods. Their averages were 211 and 456 tiller m-2, respectively. Longer deferring periods resulted in an increase in GSM (from 2, 965 to 4, 877 kg ha-1 of dry mass) and DFM (from 2, 324 to 4, 823 kg ha-1 of dry mass), but it did not influence GLBM (average of 2, 047 kg ha-1 of dry mass). In Viçosa, Minas Gerais State Brazil, Brachiaria decumbens cv. Basilisk pasture fertilized and deferred in the beginning of March must be kept deferred for about 70 days in order to conciliate both quality and quantity forage production.

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Two experiments (experiment 1 - conventional feeding and experiment 2 - feeding of the sows, starting at 109 days of pregnancy and during lactation, and the lactating piglets, with rations without soybean meal) were conducted to evaluate the effects of sources of protein (soybean meal-SBM, extruded semi-integral soybean-ESISB, and milk products-MP) on the intestinal morphology of piglets slaughtered at the 0, 5 and 15 days later at weaning. Twenty-seven piglets weaned with 25 days of age were used, being nine piglets slaughter in each slaughtering age. A 3 ×3 factorial (3 diets × 3 slaughtering ages) was studied, according to a randomized block design. The results showed that animals receiving SBM, presented lower values of villi height and villus: crypt ratio when compared to those that received ESISB or MP. The villi height and the villus: crypt ratio were not affected by the differential feeding of the sows and of the piglets before the weaning. The depth of the crypt was not affected by diets or slaughtering ages in none of the segments studied being, however, smaller in the duodenum and bigger in the jejunum and ileo of the animals of exp. 2. It was concluded that the SBM was the affected the height of the villi and the relationship villi: Crypt negatively after it weans. The intestinal morphology was more affected at five days, showing signals of recovering at 15 days after weaning and that the feeding of the sows did not affect the morphology of the segments of the thin intestine.

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The knowledge of interaction between infective larvae setting and the type of grass is important to epidemiological studies and the control of gastrointestinal nematodes in sheep. The objective of this work was to evaluate the effects of three species of forage grasses on pasture characteristics and the vertical distribution of infective larvae (L3) of gastrointestinal nematodes of woolless sheep on the grasses during the rainy season. Sixty non-periparturients ewes were used, naturally infected, equally distributed on 2ha paddocks sowed with Tanzania, star, and gamba grasses, managed under continuous grazing system, from October 2003 to March 2004, at Santa Bárbara farm, Barreiras-Bahia-Brazil. Data of three samples between December 2003 and March 2004 were analyzed by SAS, using split-plot design, with 10 replications. Infective larvae of Haemonchus spp. and Trichostrongylus spp. were observed on forage in all stratus of vertical layer of the grasses without a defined pattern. Pastures with different characteristics under continuous grazing system had good conditions for developing infective larvae of sheep.

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The paca (Cuniculus paca) is the second largest rodent of the Brazilian fauna. The excellent meat quality of this specie encourages the development of their commercial production. Moreover, this animal can become a viable alternative for animal experimentation although there exists scarce detailed information concerning their morphology. Therefore the purpose of this study is to describe the morphology, morphometry and ultrastructure in segments of the cranial and caudal portions of vena cava in four adult males and females of Cuniculus paca from the squad of Wild Animals Sector of Animal Science Department of FCAV-Unesp. Parts of the segments were examined by light microscopy and part by scanning electron microscopy. Thickness measures of the tunica intima and media complex and tunica adventitia of the vena cava were taken and analyzed using T test (p<0.05). In vena cava the thickness values of the intima, media and adventitia, for all animals, were significantly higher in the cranial segment. The layers of the vessel walls showed variations in structure and thickness, presumably due to an adaptation to functional demand.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Biociências e Biotecnologia Aplicadas à Farmácia - FCFAR

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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