836 resultados para Teaching and learning of Natural Sciences in the early years
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Five microsatellite loci were isolated and characterized within the woolly mouse opossum (Micoureus paraguayanus), a Neotropical marsupial, using an enrichment cloning procedure. Between four and seven alleles were detected per locus, with expected heterozygosity ranging from 0.358 to 0.560. These microsatellites should provide useful markers in a variety of genetic analyses to examine parentage, inbreeding, population structure and population dynamics in fragmented forest habitats.
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1. The C-13 turnover rates of the liver and thoracic pectoral muscle of growing broilers were determined by feeding diets with varying C-13 content.2. Male chicks ( 1- d- old) were subjected to treatments based on free choice of 5 different mixes of energy and protein sources from plants with C-3 and C-4 photosynthetic pathways that had differing C-13 content. Rice bran ( R) and soybean meal ( S) were the C-3 sources, while maize ( C) and maize gluten meal ( G) were the C-4 sources. Choices were R + S, C + G, R + G, C + S or R + C +G + S. The 6th treatment was a complete feed ( CF) that was similar to a commercial broiler feed.3. The isotopic composition of the birds' tissues was representative of the isotopic composition of the diets. The assimilation was faster for C-3, in both liver and muscle, than for C-4 diets, and give the delta per mil difference between the diet and tissues.4. The liver is the most active metabolic tissue and gave more rapid isotope turnover than in muscle.
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Molecular chaperones perform folding assistance in newly synthesized polypeptides preventing aggregation processes, recovering proteins from aggregates, among other important cellular functions. Thus their study presents great biotechnological importance. The present work discusses the mining for chaperone-related sequences within the sugarcane EST genome project database, which resulted in approximately 300 different sequences. Since molecular chaperones are highly conserved in most organisms studied so far, the number of sequences related to these proteins in sugarcane was very similar to the number found in the Arabidopsis thaliana genome. The Hsp70 family was the main molecular chaperone system present in the sugarcane expressome. However, many other relevant molecular chaperones systems were also present. A digital RNA blot analysis showed that 5'ESTs from all molecular chaperones were found in every sugarcane library, despite their heterogeneous expression profiles. The results presented here suggest the importance of molecular chaperones to polypeptide metabolism in sugarcane cells, based on their abundance and variability. Finally, these data have being used to guide more in deep analysis, permitting the choice of specific targets to study. (c) 2006 Elsevier GmbH. All rights reserved.
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The thermal structure, heat content and stability were studied in Lakes Dom Helvécio and Carioca during an annual cycle. It was found that the maximum heat content, stability and work of the wind in Lake Dom Helvécio correspond to two, four and four times, respectively, the values for the Lake Carioca. These difference can be attributed to morphometric differences in the lakes. A long-term record of heat content and stability for lake Carioca is also presented. Diel variations were studied in summer and winter. The tropicality of the lakes is discussed and compared with other lacustrine systems. © 1989 Kluwer Academic Publishers.
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The studies on the characterization of eosinophils and neutrophils/ heterophils of turtles are contradictory. Some authors have pointed out the existence of two distinct cell types: eosinophils and heterophils. Other authors have proposed that eosinophils and heterophils may be the same cells in different stages of maturation. These interpretations are based only on a morphological analysis. In the blood of the turtle (Chrysemys dorbignih), a South American freshwater species, there are two types of granulocytes with eosinophilic staining pattern: the first with round cytoplasmic granules and the second with ellipsoidal cytoplasmic granules. In the present study by using histoenzymological methods for the analyses of enzymological cellular content, we found that the cells with round cytoplasmic granules were positive for nonspecific esterase and the cells with ellipsoidal granules were positives for acid phosphatase, alkaline phosphatase, nonspecific esterase and peroxidase. The results show that these cells are distinct cells and that the cells with ellipsoidal cytoplasmic granules have the same histoenzymological characteristics as the neutrophils/heterophils of mammalians and other vertebrates.
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Although rare, some anurans show multimale spawning. Herein we present data on testes mass relative to body mass for 11 leptodactylids and report multimale spawning in Leptodactylus chaquensis and Leptodactylus podicipinus. Testes mass averaged 4.13% of body mass for L. chaquensis and 0.75% for L. podicipinus. Testes size of both leptodactylid species with multimale spawning show that they are large and close to values recorded for rhacophorid frogs with multimale breeding (0.71-7.79%). Large testes size in frogs with multimale spawning supports the sperm competition hypothesis.
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An integrated and interdisciplinary research programme with native medicinal plants from tropical forests has been performed in order to obtain new forest products for sustainable use in regional markets vis-à-vis ecosystem conservation. For the success of this programme ethnopharmacological studies are very important with respect to (i) identification of useful plants including medicinal and aromatic species; (ii) recuperation and preservation of traditional knowledge about native plants; and (iii) identification of potential plants with economic value. The plants are selected with a view to evaluate efficacy and safety (pharmacological and toxicological studies), and phytochemical profile and quality control (phytochemical and chromatographic characterization). These studies are very important to add value to plant products and also to mitigate unscrupulous exploitation of medicinal plants by local communities, since multiple use of plants represents an excellent strategy for sustaining the tropical ecosystem through ex situ and in situ conservation. Thus, conservation of tropical resources is possible in conjunction with improvements in the quality of life of the traditional communities and production of new products with therapeutic, cosmetic and 'cosmeceutic' value. © NIAB 2005.
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Commissioning studies of the CMS hadron calorimeter have identified sporadic uncharacteristic noise and a small number of malfunctioning calorimeter channels. Algorithms have been developed to identify and address these problems in the data. The methods have been tested on cosmic ray muon data, calorimeter noise data, and single beam data collected with CMS in 2008. The noise rejection algorithms can be applied to LHC collision data at the trigger level or in the offline analysis. The application of the algorithms at the trigger level is shown to remove 90% of noise events with fake missing transverse energy above 100 GeV, which is sufficient for the CMS physics trigger operation. © 2010 IOP Publishing Ltd and SISSA.
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The nucleolar material of Chariesterus armatus was analyzed during spermiogenesis in cell preparations impregnated with silver nitrate. Nucleolar corpuscles were observed in spermatids at the beginning of the process, showing that this organoid is also maintained after meiosis. In addition, nucleoli were seen in the round spermatids connected to the X-chromosome (bearer of the nucleolar organizer in C. armatus), indicating de novo synthesis of nucleolar material. This differs from the reorganization of ribosomal granules, transported from meiotic spermatocytes to round spermatids, where they would support protein synthesis, which is reported for other species. We also observed connections of nucleolar corpuscles to the nuclear membrane regions where the tail and the acrosome will be formed, suggesting close involvement of the nucleolar material in the formation of these structures. In addition to the nucleolar bodies, we detected silver-positive structures, which will require new approaches to clarify their role. One of these structures, observed in the cytoplasm, appears to correspond to the chromatoid body, which has been found in several organisms, but is still poorly understood; another is a complex structure to which the tail appears to be connected. We conclude that C. armatus is an appropriate model for understanding not only the synthesis of rRNA in the spermiogenesis, but also the functional meaning of the close relationship of nucleolar material with other structures during this process.
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Includes bibliography
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Water pollution found in major rivers in Brazil has its origin from urban sewage discharges and industrial effluent, carried out by small streams and rivers crossing cities. Therefore, studies related to hydrographic micro-basins offer the opportunity to establish environmental management strategies for restoring water resources, based on diagnosis of the water quality. Despite this understanding, few studies in urban and rural areas have been performed in a systematic manner in Brazilian micro-basins. The main goal of this research was to diagnose the water resources in micro-basins in the region of the district of Americana, São Paulo state, Brazil, through the quantification of metals in water and sediment. The methodology was based on the investigation of metals (Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn), in four micro-basins, determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The most significant result showed high concentration levels of chromium (969 μg L-1), downstream of the discharge of sewage from the city of Nova Odessa. This concentration in the river was above the allowed limit of Brazilian regulation agency (50 μg L-1 for Cr). Also high levels of Cr were found in the sediment (98.9 μg g-1) collected at the same monitored site. These results are important indicators of environmental performance and anthropogenic activities to help the government establish environmental management strategies aimed at the reduction of water pollution. © 2013 WIT Press.
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Contiene organización de los trabajos, resumen de los debates y recomendaciones y conclusiones. Incluye además, definición de términos utilizados; criterios para definir las principales características y necesidades de las zonas altas de la Región Andina; lista de participantes y lista de documentos presentados en el Seminario.