188 research outputs found

    Adubação Nitrogenada para Cultivares de Mamona no Rio Grande do Sul.

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    Biomarkers for Mercury Exposure in Tropical Estuarine Fish

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    Several studies have evaluated human risks due mercury (Hg) exposure through fish consumption. However, relatively few studies have explored effects of environmental Hg concentrations in biota, especially tropical fish species. The aim of this work was to assess in situ hematological, biochemical and genotoxic effects in tropical fish due to environmental exposure to mercury in estuarine ecosystems. A total of 282 fishes were collected from September 2003 to October 2005 in two estuarine areas: Ribeira Bay (reference area - 22° 55’ to 23° 02’ S and 44° 18’ to 44° 26’ W) and Guanabara Bay (highly impacted area by human activities - 22° 40’ to 23° 00’ S and 43° 00’ to 43° 20’ E). Total mercury levels in fish from Guanabara were twice higher than in Ribeira bay for the catfish species Genidens genidens (Ariidae), with significant differences among areas after standardization using length intervals (exposure time indicator). The species Haemulon steindachneri (Haemulidae) showed the highest mercury concentration, reflecting its position in trophic chain. Among effect biomarkers, only haematocrit, global leucometry and micronucleus assays seemed to reflect the differences on mercury exposure among areas, what may support their use for evaluations of fish exposure to mercury compounds. However, it’s necessary both laboratory experiments to establish cause-effect relationship and a continuous in situ study to obtain more information, involving more trophic levels, searching for sensible species to mercury exposure

    Inclusion of crushed corn grains and citrus pulp improves the quality of soybean silage

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    We aimed to evaluate the effect of the inclusion of corn and citrus pulp as additives in soybean silage made in plastic (PVC) tubes. The experimental design was completely randomized, with a 2x4 factorial arrangement consisting of two additive groups (corn and citrus pulp) and four inclusion levels (no inclusion, 7, 14 and 21%). The experiment was conducted at the Forage Sector of the Lageado Experimental Farm, Faculty of Veterinary Medicine and Animal Science, UNESP, Botucatu, SP, and chemical composition analysis was carried out at the Laboratory of Bromatology. The soybean variety used was BMX Potência RR. Mechanical harvest occurred at the R7 phenological stage, at a height of 15 cm, using a harvester equipped with a two-row platform. The material was chopped into medium particles of 3 to 6 mm. After 45 days, the silages were analyzed for dry matter, crude protein (CP), total digestible nutrients, pH, ethereal extract, neutral detergent fiber, acid detergent fiber, lignin, total dry matter loss, and total carbohydrates (CHOS). The inclusion of corn (21%) and citrus pulp (14 and 21%) reduced CP values (P<0.05). Control silage contained less CHOS (P<0.05). The inclusion of corn meal is better than citrus pulp to improve the values of soybean silage

    Compatibilidade de milho transgênico com o parasitoide Trichogramma pretiosum.

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    Correlation of shear strength and physicochemical properties as a criterion for the selection of accessions of Paspalum grasses.

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    The present study aimed to evaluate the application of shear strength and its correlations with leaf blade morphological and chemical variables as a tool capable of detecting differences between species and accessions of the genus Paspalum in the early stages of a forage plant breeding programme. A total of 13 Paspalum accessions from two species (Paspalum atratum and Paspalum regnellii) were subjected to analyses of shear strength, which also analysed the neutral detergent fibre, acid detergent fibre, lignin, and digestibility. Morphological measurements were also performed to standardize the shear strength per unit of leaf tissue. The experimental design consisted of complete randomized blocks, with four replications and eight cuts performed over 2 years. Shear strength was evaluated for its potential usefulness for detecting differences between accessions of the same species and the correlations of accessions. It was possible to use the shear strength measured with the texturometer to detect differences between species and accessions of the Paspalum genus. The results showed significant correlations of shear strength and neutral detergent fibre (r = 0.49), and negative correlations were found between digestibility and shear strength (r = -0.55). These correlations were maintained when the strength variables were standardized according to the morphological variables. Thus, shear strength can be used in the initial stages of the selection of species of the genus Paspalum

    Mercury exposure, malaria, and serum antinuclear/antinucleolar antibodies in amazon populations in Brazil: a cross-sectional study

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    BACKGROUND: Mercury is an immunotoxic metal that induces autoimmune disease in rodents. Highly susceptible mouse strains such as SJL/N, A.SW, B10.S (H-2(s)) develop multiple autoimmune manifestations after exposure to inorganic mercury, including lymphoproliferation, elevated levels of autoantibodies, overproduction of IgG and IgE, and circulating immune complexes in kidney and vasculature. A few studies have examined relationships between mercury exposures and adverse immunological reactions in humans, but there is little evidence of mercury-associated autoimmunity in humans. METHODS: To test the immunotoxic effects of mercury in humans, we studied communities in Amazonian Brazil with well-characterized exposures to mercury. Information was collected on diet, mercury exposures, demographic data, and medical history. Antinuclear and antinucleolar autoantibodies (ANA and ANoA) were measured by indirect immunofluorescence. Anti-fibrillarin autoantibodies (AFA) were measured by immunoblotting. RESULTS: In a gold mining site, there was a high prevalence of ANA and ANoA: 40.8% with detectable ANoA at ≥1:10 serum dilution, and 54.1% with detectable ANA (of which 15% had also detectable ANoA). In a riverine town, where the population is exposed to methylmercury by fish consumption, both prevalence and levels of autoantibodies were lower: 18% with detectable ANoA and 10.7% with detectable ANA. In a reference site with lower mercury exposures, both prevalence and levels of autoantibodies were much lower: only 2.0% detectable ANoA, and only 7.1% with detectable ANA. In the gold mining population, we also examined serum for AFA in those subjects with detectable ANoA (≥1:10). There was no evidence for mercury induction of this autoantibody. CONCLUSIONS: This is the first study to report immunologic changes, indicative of autoimmune dysfunction in persons exposed to mercury, which may also reflect interactions with infectious disease and other factors
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